113 results on '"Kim, Jinwoo"'
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2. Local Structures of Ex-Solved Nanoparticles Identified by Machine-Learned Potentials
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Kang, Sungwoo, Kim, Jun Kyu, Kim, Hyunah, Son, You-Hwan, Chang, Jaehee, Kim, Jinwoo, Kim, Dong-Wook, Lee, Jong-Min, and Kwon, Hyuk Jae
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In this study, we identify the local structures of ex-solved nanoparticles using machine-learned potentials (MLPs). We develop a method for training machine-learned potentials by sampling local structures of heterointerface configurations as a training set with its efficacy tested on the Ni/MgO system, illustrating that the error in interface energy is only 0.004 eV/Å2. Using the developed scheme, we train an MLP for the Ni/La0.5Ca0.5TiO3ex-solution system and identify the local structures for both exo- and endo-type particles. The established model aligns well with the experimental observations, accurately predicting a nucleation size of 0.45 nm. Lastly, the density functional theory calculations on the established atomistic model verify that the kinetic barrier for the dry reforming of methane are substantially reduced by 0.49 eV on the ex-solved catalysts compared to that on the impregnated catalysts. Our findings offer insights into the local structures, growth mechanisms, and underlying origin of the catalytic properties of ex-solved nanoparticles.
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- 2024
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3. Motion correction algorithm for cone-beam computed tomography
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Fahrig, Rebecca, Sabol, John M., Li, Ke, Lee, Jiyoung, Kim, Jinwoo, and Cho, Min Kook
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- 2024
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4. Deep learning-based dose estimation in cone-beam computed tomography
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Fahrig, Rebecca, Sabol, John M., Li, Ke, Kim, Jinwoo, Kim, Ho Kyung, and Cho, Minkook
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- 2024
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5. The role of state preparation in time-bin entangled photon pair generation for quantum communication
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Hemmer, Philip R., Migdall, Alan L., Kim, Jinwoo, Park, Jiho, Kim, Hong-seok, Kim, Guhwan, Slusar, Tetiana V., Kim, Jintae, Park, Jaegyu, Moon, Kiwon, and Ju, Jung Jin
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- 2024
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6. Experimental Study on Indentation Behavior of U-Type Section Steel Piling
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Kim, JinWoo, Kim, TaeHoon, Park, HaeYong, and Kim, TaeSoo
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Steel sheet piles are known for their straightforward assembly and construction, making them a popular choice that is often repurposed for other building projects once disassembled. Regarding the re-use of these steel sheet piles, understanding their behavior during penetration into the soil becomes pivotal. This study focuses on assessing the potential reusability of steel sheet piles as they penetrate into the soil. A laboratory-scale experiment involving the insertion of a steel sheet pile into a sand-filled tank was conducted. The experimental variables were the relative density of the soil, length of the steel sheet pile, and penetration method. The behavior of the sheet pile was analyzed, including the force-insertion length relationship and the strain of deformation occurring locally in the sheet pile. The results indicated that higher relative soil densities led to increased strain within the sheet pile. The strain values remained within the elastic range during the experiment. Notably, when interpenetrating the steel pile with a coupling mating joint test specimen, the strain showed an inverted mountain-shaped distribution within the interlock.
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- 2024
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7. Simultaneous Detection of Infectious Diseases Using Aptamer-Conjugated Gold Nanoparticles in the Lateral Flow Immunoassay-Based Signal Amplification Platform
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Kim, Jinwoo, Baek, Sowon, Nam, Jungmin, Park, Jeongeun, Kim, Kihyeun, Kang, Juyoung, and Yeom, Gyuho
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Various platforms for the accurate diagnosis of infectious diseases have been studied because of the emergence of coronavirus disease (COVID-19) in 2019. Recently, it has become difficult to distinguish viruses with similar symptoms due to the continuous mutation of viruses, and there is an increasing need for a diagnostic method to detect them simultaneously. Therefore, we developed a paper-based rapid antigen diagnostic test using DNA aptamers for the simultaneous detection of influenza A, influenza B, and COVID-19. Aptamers specific for each target viral antigen were selected and attached to AuNPs for application in a rapid antigen diagnosis kit using our company’s heterogeneous sandwich-type aptamer screening method (H-SELEX). We confirmed that the three viruses could be detected on the same membrane without cross-reactivity based on the high stability, specificity, and binding affinity of the selected aptamers. Further, the limit of detection was 2.89 pg·mL–1when applied to develop signal amplification technology; each virus antigen was detected successfully in diluted nasopharyngeal samples. We believe that the developed simultaneous diagnostic kit, based on such high accuracy, can distinguish various infectious diseases, thereby increasing the therapeutic effect and contributing to the clinical field.
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- 2024
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8. Photocatalytic Activation of Aryl(trifluoromethyl) Diazos to Carbenes for High-Resolution Protein Labeling with Red Light
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Cabanero, David C., Kariofillis, Stavros K., Johns, Andrew C., Kim, Jinwoo, Ni, Jizhi, Park, Sangho, Parker, Dann L., Ramil, Carlo P., Roy, Xavier, Shah, Neel H., and Rovis, Tomislav
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State-of-the-art methods in photoproximity labeling center on the targeted generation and capture of short-lived reactive intermediates to provide a snapshot of local protein environments. Diazirines are the current gold standard for high-resolution proximity labeling, generating short-lived aryl(trifluoromethyl) carbenes. Here, we present a method to access aryl(trifluoromethyl) carbenes from a stable diazo source viatissue-penetrable, deep red to near-infrared light (600–800 nm). The operative mechanism of this activation involves Dexter energy transfer from photoexcited osmium(II) photocatalysts to the diazo, thus revealing an aryl(trifluoromethyl) carbene. The labeling preferences of the diazo probe with amino acids are studied, showing high reactivity toward heteroatom−H bonds. Upon the synthesis of a biotinylated diazo probe, labeling studies are conducted on native proteins as well as proteins conjugated to the Os photocatalyst. Finally, we demonstrate that the conjugation of a protein inhibitor to the photocatalyst also enables selective protein labeling in the presence of spectator proteins and achieves specific labeling of a membrane protein on the surface of mammalian cells via a two-antibody photocatalytic system.
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- 2024
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9. Experimental and Numerical Study on Behaviors of Double-shear Four-Bolted Connection with Austenitic Stainless Steel
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Lee, Dongkeun, Kim, Jinwoo, Lee, KangSeok, and Kim, TaeSoo
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It is well known that stainless steel has many advantages such as superb durability, ductility, and corrosion resistance. Thus, the use of stainless steel for various structural members in construction fields is recently increasing. Structural behaviors of bolted and welded connections, compressive and flexural members, beam-column joints, seismic devices etc. have been conducted experimentally and numerically and thus new design methods have been proposed. Hence, in this study, both experiment and finite element analysis were conducted to assess the block shear failure behaviors of double-shear four-bolted connections made of austenitic stainless steel (STS304) with thinner plate and larger end distance, which are beyond the range of previous literature. The main parameter was end distance and edge distance. Block shear strengths by parametric analysis and test results study were compared with design predictions. It is found that current design equations tended to significantly underestimated test and analysis results. Therefore, modified block shear strength equation was recommended for austenitic stainless steel double shear bolted connection treated in this study.
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- 2024
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10. Experimental Study on the Dynamic Characteristics of Steel Slit Dampers with and Without Out-of-Plane Deformation Restraints
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Kim, Jinwoo, Kwon, U-Jin, Park, Hae-Yong, Kim, Young-Ju, and Kim, Jae-Bong
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Increasing the strut thickness to prevent or restrain out-of-plane deformation increases in-plane stiffness and strength, leading to excessive stress concentration at the junction of the damper and damper systems. We developed restraining panels to suppress out-of-plane deformation and enhance the deformation performance of steel slit dampers. Additionally, we investigated the impact of applying restraining panels on the plastic deformation capability and strength of the steel slit dampers. The experimental variables included (1) the presence of out-of-plane deformation restraining panels, (2) the ratio of effective height to strut width (aspect ratio), (3) the ratio of strut thickness to width (thickness-width ratio), and (4) loading amplitude. When the restraining panels were not applied, cracks occurred at the end of the strut. In the test specimen where out-of-plane deformation occurred, the cumulative plastic deformation angle improved from 1.97 to 3.29 times owing to the use of restraining panels. However, the strength increase ratio for all test specimens ranged from approximately 1.3–1.7, indicating that minimal strength enhancement was attributable to the restraining panels.
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- 2024
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11. A PPA Study for Heterogeneous 3-D IC Options: Monolithic, Hybrid Bonding, and Microbumping
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Kim, Jinwoo, Zhu, Lingjun, Torun, Hakki Mert, Swaminathan, Madhavan, and Lim, Sung Kyu
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In this article, we present three commercial-grade 3-D IC designs based on state-of-the-art design technologies, specifically microbumping (3-D die stacking), hybrid bonding (wafer-on-wafer bonding), and monolithic 3-D (M3D) ICs. To highlight tradeoffs present in these three designs, we perform analyses on power, performance, and area (PPA) and the clock tree. We also model the tier-to-tier interconnection in each 3-D IC methodology and analyze signal integrity (SI) to assess the reliability of each design. From our experiments using the OpenPiton benchmark, the hybrid bonding design shows the best timing improvement of 81.4% when compared to its 2-D counterpart, while microbumping shows the best reliability among 3-D IC designs. Moreover, we expand our study to the commercial processor architecture, which is Arm Cortex-A53, with the new set of 3-D integration options. In addition, we show the microbump assignment methodology to handle a large number of 3-D interconnections in the microbumping 3-D design. We also perform SI on the new set of 3-D intertier/interdie connections to discuss the reliability based on their physical dimensions. With a new benchmark design, the hybrid-bonding 3-D shows the best energy–delay-product (EDP) improvement, which is 25.8% compared to 2-D, and the largest eye-opening among 3-D integration options.
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- 2024
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12. MNET++: Music-Driven Pluralistic Dancing Toward Multiple Dance Genre Synthesis
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Kim, Jinwoo, Kwon, Beom, Kim, Jongyoo, and Lee, Sanghoon
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Numerous task-specific variants of autoregressive networks have been developed for dance generation. Nonetheless, a severe limitation remains in that all existing algorithms can return repeated patterns for a given initial pose, which may be inferior. We examine and analyze several key challenges of previous works, and propose variations in both model architecture (namely MNET++) and training methods to address these. In particular, we devise the beat synchronizer and dance synthesizer. First, generated dance should be locally and globally consistent with given music beats, circumvent repetitive patterns, and look realistic. To achieve this, the beat synchronizer implicitly catches the rhythm enabling it to stay in sync with the music as it dances. Then, the dance synthesizer infers the dance motions in a seamless patch-by-patch manner conditioned by music. Second, to generate diverse dance lines, adversarial learning is performed by leveraging the transformer architecture. Furthermore, MNET++ learns a dance genre-aware latent representation that is scalable for multiple domains to provide fine-grained user control according to the dance genre. Compared with the state-of-the-art methods, our method synthesizes plausible and diverse outputs according to multiple dance genres as well as generates remarkable dance sequences qualitatively and quantitatively.
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- 2023
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13. Electron-Binding Dynamics of the Dipole-Bound State: Correlation Effect on the Autodetachment Dynamics
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Kang, Do Hyung, Cho, Kwang Hyun, Kim, Jinwoo, Eun, Han Jun, Rhee, Young Min, and Kim, Sang Kyu
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The nature of the electron-binding forces in the dipole-bound states (DBS) of anions is interrogated through experimental and theoretical means by investigating the autodetachment dynamics from DBS Feshbach resonances of ortho-, meta-, and para-bromophenoxide (BrPhO–). Though the charge-dipole electrostatic potential has been widely regarded to be mainly responsible for the electron binding in DBS, the effect of nonclassical electron correlation has been conceived to be quite significant in terms of its static and/or dynamic contributions toward the binding of the excess electron to the neutral core. State-specific real-time autodetachment dynamics observed by picosecond time-resolved photoelectron velocity-map imaging spectroscopy reveal that the autodetachment processes from the DBS Feshbach resonances of BrPhO–anions cannot indeed be rationalized by the conventional charge-dipole potential. Specifically, the autodetachment lifetime is drastically lengthened depending on differently positioned Br-substitution, and this rate change cannot be explained within the framework of Fermi’s golden rule based on the charge-dipole assumption. High-level ab initioquantum chemical calculations with EOM-EA-CCSD, which intrinsically takes into account electron correlations, generate more reasonable predictions on the binding energies than density functional theory (DFT) calculations, and semiclassical quantum dynamics simulations based on the EOM-EA-CCSD data excellently predict the trend in the autodetachment rates. These findings illustrate that static and dynamic properties of the excess electron in the DBS are strongly influenced by correlation interactions among electrons in the nonvalence orbital of the dipole-bound electron and highly polarizable valence orbitals of the bromine atom, which, in turn, dictate the interesting chemical fate of exotic anion species.
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- 2023
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14. Transferable Graph Neural Network-Based Delay-Fault Localization for Monolithic 3-D ICs
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Hung, Shao-Chun, Banerjee, Sanmitra, Chaudhuri, Arjun, Kim, Jinwoo, Lim, Sung Kyu, and Chakrabarty, Krishnendu
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Monolithic 3-D (M3D) integration is a promising technology for achieving high performance and low-power consumption. However, the limitations of current M3D fabrication flows lead to performance degradation of devices in the top tier and unreliable interconnects between tiers. Fault localization at the tier level is therefore necessary to enhance yield learning, For example, tier-level localization can enable targeted diagnosis and process optimization efforts. In this article, we develop a graph neural network-based diagnosis framework to efficiently localize faults to a device tier. The proposed framework can be used to provide rapid feedback to the foundry and help enhance the quality of diagnosis reports generated by commercial tools. Results for four M3D benchmarks, with and without response compaction, show that the proposed solution achieves up to 32.86% improvement in diagnostic resolution with less than 1% loss of accuracy, compared to results from commercial tools. The proposed framework has also been demonstrated to be transferable to perform diagnosis on various design configurations without performance degradation.
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- 2023
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15. Novel Porous Organic Polymer Catalyst with Phosphate and Sulfonic Acid Sites for Facile Esterification of Levulinic Acid
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Kim, Jinwoo, Ravi, Seenu, Kim, Kijun, Choi, Yujin, Park, Hyung-Ho, and Bae, Youn-Sang
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Biomass-derived value-added materials such as levulinic acid (LA) are favorable natural resources for producing ester-based biolubricants owing to their biodegradability, nontoxicity, and excellent metal-adhering properties. However, highly active catalysts must be developed to carry out efficient esterification of LA with aliphatic alcohols, especially long-chain aliphatic alcohols. In this study, we developed a novel porous covalent organic polymer catalyst (BPOP-SO3H) with dual acid sites, phosphate and sulfonic acid sites, for the esterification of LA. The prepared BPOP-SO3H catalyst was verified using various surface analysis techniques. BPOP-SO3H exhibited 98% LA conversion with n-butanol and 99% selectivity for butyl levulinate ester within 30 min, which is superior to that of most reported catalysts. BPOP-SO3H also showed high LA conversion and ester selectivity when other aliphatic alcohols were used. Moreover, BPOP-SO3H showed good recyclability for five consecutive cycles. We believe that incorporating a high density of acid sites into a porous polymer with a large surface area and hierarchical pores is a promising approach for developing heterogeneous acid catalysts for the production of alkyl levulinate esters from LA.
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- 2023
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16. Experimental Study on the Tensile Behavior of Interlocks on U-Type Section Steel Piling
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Kim, JinWoo, Park, HaeYong, Kim, TaeHoon, and Kim, TaeSoo
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Sheet piles are used in various construction field applications, such as retaining walls, slope reinforcement, breakwaters, and ports, owing to their excellent strength, light weight, waterproofing, durability, and workability. The U-type section steel piling, which is a type of sheet pile, is composed of hollow trapezoidal sections with interlocks at both ends. At the construction site, a structure is formed by assembling the interlocks of each cross-section in a simple fitting type using the driving or indentation method. Interlock is an important part of connecting steel sheet piles. The shape, size, and steel type in the interlock affect the connection quality and structural performance of the structure. In this study, tensile tests were performed on test specimens connected in series in a simple fitting type for the interlock, which is an important component of the U-type section steel piling. It was observed that the load–displacement relationship temporarily decreased and then increased. In addition, formula for calculating the maximum strength of interlock was discussed and the predictions were compared with the experimental results, and the high consistency of the formula was verified.
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- 2023
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17. Human-Machine Intelligence
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Zhang, Cheng, Kim, Jinwoo, Jeon, Jungho, Xing, Jinding, Ahn, Changbum R., Tang, Pingbo, and Cai, Hubo
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- 2023
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18. Pathogen-induced autophagy regulates monolignol transport and lignin formation in plant immunity
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Jeon, Hwi Seong, Jang, Eunjeong, Kim, Jinwoo, Kim, Seu Ha, Lee, Myoung-Hoon, Nam, Myung Hee, Tobimatsu, Yuki, and Park, Ohkmae K.
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ABSTRACTThe evolutionary plant-pathogen arms race has equipped plants with the immune system that can defend against pathogens. Pattern-triggered immunity and effector-triggered immunity are two major branches of innate immunity that share immune responses, including oxidative bursts, transcriptional reprogramming, and cell wall modifications such as lignin deposition. In a previous study, we reported that lignin rapidly accumulates in pathogen-infected Arabidopsisleaves and acts as a mechanical barrier, spatially restricting pathogens and cell death. Lignin deposition into the cell wall is a three-step process: monolignol biosynthesis, transport, and polymerization. While monolignol biosynthesis and polymerization are relatively well understood, the mechanism of monolignol transport remains unclear. In this study, we show that macroautophagy/autophagy modulates pathogen-induced lignin formation. Lignification and other immune responses were impaired in autophagy-defective atg(autophagy-related) mutants. In microscopy analyses, monolignols formed punctate structures in response to pathogen infection and colocalized with autophagic vesicles. Furthermore, autophagic activity and lignin accumulation were both enhanced in dnd1(defense, no death 1) mutant with elevated disease resistance but no cell death and crossing dnd1-1with atgmutants resulted in a lignin deficit, further supporting that lignin formation requires autophagy. Collectively, these findings demonstrate that lignification, particularly monolignol transport, is achieved through autophagic membrane trafficking in plant immunity.Abbreviations: ABC transporter: ATP-binding cassette transporter; ACD2/AT4G37000: accelerated cell death 2; ATG: autophagy-related; C3′H/AT2G40890: p-coumaroyl shikimate 3-hydroxylase; C4H/AT2G30490: cinnamate 4-hydroxylase; CA: coniferyl alcohol; CaMV: cauliflower mosaic virus; CASP: Casparian strip membrane domain protein; CASPL: CASP-like protein; CBB: Coomassie Brilliant Blue; CCoAOMT1/AT4G34050: caffeoyl-CoA O-methyltransferase 1; CCR1/AT1G15950: cinnamoyl-CoA reductase 1; CFU: colony-forming unit; COMT1/AT5G54160: caffeic acid O-methyltransferase 1; Con A: concanamycin A; DMAC: dimethylaminocoumarin; DND1/AT5G15410: defense, no death 1; CNGC2: cyclic nucleotide-gated channel 2; ER: endoplasmic reticulum; ESB1/AT2G28670/DIR10: enhanced suberin 1; ETI: effector-triggered immunity; EV: extracellular vesicle; F5H/AT4G36220: ferulate-5-hydroxylase; Fluo-3 AM: Fluo-3 acetoxymethyl ester; GFP: green fluorescent protein; HCT/AT5G48930: p-hydroxycinnamoyl-CoA:quinate/shikimate p-hydroxycinnamoyltransferase; HR: hypersensitive response; LAC: laccase; LTG: LysoTracker Green; LSD1/AT4G200380: lesion stimulating disease 1; PAL1/AT2G37040: phenylalanine ammonia-lyase 1; PAMP: pathogen-associated molecular patterns; PCD: programmed cell death; PE: phosphatidylethanolamine; PRX: peroxidase; PstDC3000: Pseudomonas syringepv. tomatoDC3000; PTI: pattern-triggered immunity; SA: salicylic acid; SD: standard deviation; SID2/AT1G7410: SA induction-deficient 2; UGT: UDP-glucosyltransferase; UPLC: ultraperformance liquid chromatography; UPS: unconventional protein secretion; V-ATPase: vacuolar-type H+-translocating ATPase
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- 2023
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19. Power, Performance, Area, and Cost Analysis of Face-to-Face-Bonded 3-D ICs
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Agnesina, Anthony, Brunion, Moritz, Kim, Jinwoo, Garcia-Ortiz, Alberto, Milojevic, Dragomir, Catthoor, Francky, Mirabelli, Gioele, Komalan, Manu, and Lim, Sung Kyu
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This article presents a power, performance, area, and cost (PPAC) analysis for large-scale 3-D processor designs based on face-to-face wafer-to-wafer (W2W) and collective die-to-wafer (Co-D2W) bonding technologies. From evaluating our cost model on a comprehensive portfolio of technology nodes, we investigate a typically disregarded opportunity in 3-D through diverse computer-age statistical methods: area savings due to buffer savings and better routability, offering unforeseen, and considerable cost savings. We explore the viability of this factor with the feedback of a state-of-the-art 3-D memory-on-logic implementation flow. We show how this affects the PPAC of full-chip GDS implementations of a large-scale manycore processor design. Experiments show that our memory-on-logic 3-D implementation offers 7% silicon area savings, resulting in a 53.5% footprint reduction. We also obtained a 40% power-performance-cost improvement compared with the 2-D counterparts.
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- 2023
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20. PI_BPNN controller for transient response improvement of LLC resonant converter
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Kim, Hokyeong, Kim, Jinwoo, Chin, Taehoon, Choi, Hongseok, and Cho, Younghoon
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This paper proposes the proportional integral (PI) backpropagation neural network (BPNN) algorithm to improve the transient voltage control performance in an LLC resonant converter whose voltage gain is highly nonlinear. In the proposed method, the PI linear controller roughly regulates the operating frequency of the LLC converter according to the voltage gain. Moreover, the BPNN nonlinear controller compensates for the frequency in the transient and steady states. It also improves the dynamics. Compared with traditional artificial neural network algorithms, the proposed BPNN can reduce the computational burden of the digital controller and improve the accuracy of the time-series prediction by reflecting previously predicted results in the learning process. Hence, the proposed method is suitable for real-time applications, such as power electronic converters. The structure and the learning procedure of the proposed PI-BPNN controller are explained in detail, together with the modeling and the control scheme of the LLC converter. A 5.5 kW LLC converter prototype is built and tested to verify the performance of the proposed method. The load step experimental results show that compared with the traditional PI control algorithm, the proposed PI-BPNN reduces the transient response time by up to 25%.
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- 2023
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21. Synchronous frame phase compensation for applying modulated model predictive control to high-speed motors
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Choi, Dongmin, Kim, Jinwoo, Lee, Jung-Yong, Choi, Seungil, and Cho, Younghoon
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This paper proposes a phase compensation in the synchronous frame for applying modulated model predictive control (MMPC) to a high-speed motor. In the conventional MMPC, when future values for the control variable are predicted, it is necessary to assume that the other variables have constant values during one sample period. However, under a high electrical frequency, this assumption provokes a prediction error, which affects the steady state response. Hence, to improve the precision for predicting variables, the phase variation in the synchronous frame is analyzed and compensation methods are proposed. In particular, the instantaneous variance for the back electromotive force during one sampling period is analyzed, and a compensation method for its variance is derived. To validate the effectiveness of the proposed compensation methods, a motor drive system that can be operated at 3000 rpm is built and tested. Simulation and experiments are performed while comparing the transient and steady state responses.
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- 2023
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22. 25 kW 1200 V unidirectional DC solid-state circuit breaker design with SiC MOSFET desaturation detection
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Kim, Jinwoo, Yoon, Dongkwan, Choi, Dongmin, Lee, Jung-Yong, and Cho, Younghoon
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This paper proposes a silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) based a solid-state circuit breaker (SSCB) with a desaturation detection method. Since the SiC MOSFET has a higher switching speed than general semiconductors, the SSCB can achieve faster and higher blocking performance. However, protecting SiC MOSFETs from short circuit conditions is not easy, because fault blocking occurs with a large overshoot in the drain-source voltage. Thus, this paper proposes design methods for a snubber circuit and a desaturation detecting method to protect SiC MOSFETs. This design method is based on SSCB blocking operation equations, and a simulation is conducted to verify the equations. In addition, the stray components of the printed circuit board (PCB) are simulated to make an exact comparison with experiments. An SSCB is built based on the equation and tested under fault conditions. The experimental results demonstrate that the proposed SSCB blocks short circuit current of less than 0.9 µs. Finally, a thermal test is conducted at the rated load to validate the heat control performance.
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- 2023
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23. Built-In Self-Test of High-Density and Realistic ILV Layouts in Monolithic 3-D ICs
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Chaudhuri, Arjun, Banerjee, Sanmitra, Kim, Jinwoo, Lim, Sung Kyu, and Chakrabarty, Krishnendu
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Nanoscale interlayer vias (ILVs) in monolithic 3-D (M3D) ICs have enabled high-density vertical integration of logic and memory tiers. However, the sequential assembly of M3D tiers via wafer bonding is prone to variability in the immature fabrication process and manufacturing defects. The yield degradation due to ILV faults can be mitigated via dedicated test and diagnosis of ILVs using built-in self-test (BIST). Prior work has carried out fault localization for a regular 1-D placement of ILVs in the M3D layout where shorts are assumed to arise only between unidirectional ILVs. However, to minimize wirelength in M3D routing, ILVs may be irregularly placed by a place-and-route tool, and shorts can also occur between an up-going ILV and a down-going ILV. To test and localize faults in realistic ILV layouts, we present a new BIST framework that is optimized for test time and PPA overhead. We also present a graph-theoretic approach for representing potential fault sites in the ILVs and carry out inductive fault analysis to drop noncritical sites. We describe a procedure for optimally assigning ILVs to the BIST pins and determining the BIST configuration for test-cost minimization. Evaluation results for M3D benchmarks demonstrate the effectiveness of the proposed framework.
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- 2023
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24. Investigating Structural Effects of Quaternizing Additives on Shape Transitions of Block Copolymer Particles
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Tan, Zhengping, Kim, Eun Ji, Phan, Tan Ngoc-Lan, Kim, Jinwoo, Shin, Jaeman J., Ku, Kang Hee, and Kim, Bumjoon J.
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Co-assembly of block copolymers (BCPs) and organic/inorganic additives affords the design of various hierarchical nanostructures. In this work, we investigate the shape-changing capabilities of poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) BCP particles upon quaternization with a series of bromoalkyl benzene additives with different alkyl spacer lengths. The bromoalkyl benzene additives exhibit different hydrolyzing and quaternizing behaviors depending on their chemical structures. When benzyl bromide (BB) is used, the PS-b-P2VP BCP particles exhibit dramatic shape transitions from ellipsoids to ellipsoids with swelled discs, swelled buds, and vesicles. These morphological transitions are attributed to the synergistic quaternization and protonation of the P2VP chains via the hydrolysis of BB in aqueous media. Upon increasing the molar ratio of BB to 2VP units, the pH of the surrounding aqueous solutions significantly decreases, and the protonated P2VP domains are swelled by the surrounding water, which eventually results in interfacial instability of the emulsion interface. When the additives contain longer alkyl spacers (e.g., ethyl, butyl, and hexyl), the additives lead to a narrower range of quaternization-dependent particle morphologies due to the absence of the hydrolysis of the additives. However, a broader spectrum of particle shapes is observed for additives with longer alkyl chains, due to their stronger quaternizing capabilities. We carefully investigate the structural effect of the quaternizing additives on the change of pH, degree of quaternization, and interfacial tension to elucidate the mechanism of the additive-driven particle morphology transitions.
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- 2022
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25. State-Specific Chemical Dynamics of the Nonvalence Bound State of the Molecular Anions
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Kang, Do Hyung, Kim, Jinwoo, Eun, Han Jun, and Kim, Sang Kyu
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Nonvalence bound states (NBS) are anionic states where the excess electron is extremely loosely bound to the neutral core through long-range potentials. In contrast to the valence orbitals of which the electron occupancy determines the molecular structure, as well as the chemical reactivity, the nonvalence orbital is quite diffuse and located far from the neutral core. The NBS can be classified into the dipole-bound state (DBS), quadruple-bound state (QBS), or correlation-bound state (CBS) according to the nature of the electron-neutral interaction, although their interaction potentials may cooperatively contribute. The NBS is ubiquitous in nature and has the strong implications in atmospheric, interstellar, or biological chemistry. Accordingly, NBS has long been conceived to play the role of the doorway into the formation of a stable anion or dissociative electron attachment (DEA). Despite intensive and extensive studies, however, the quantum-mechanical nature of NBS is still far from being thorough understanding. Herein, we describe a new aspect of state-specific NBS-mediated chemical dynamics, which has been revealed through a series of recent studies by our group. We have employed picosecond time–resolved pump–probe spectroscopy combined with cryogenically cooled ion trap and velocity-map imaging techniques to study closed-shell anions generated by electrospray ionization. DBS vibrational Feshbach resonances are prepared by the optical excitation of phenoxide, for instance, and their individual lifetimes have been precisely measured in a state-specific manner to reveal the strong mode-dependency of the autodetachment rate. Fermi’s golden rule turns out to be extremely useful for a rational explanation of the experiment, although the more sophisticated theoretical model is desirable for the more quantitative analysis. For the DBS of para-chlorophenoxide or para-bromophenoxide where the polarizability of neutral core is substantial, the Fermi’s golden rule based on the charge-dipole potential needs to be significantly modified to include the correlation effects to explain the exceptionally slow autodetachment rates. For the QBS of 4-cyanophenoxide, the mode-specific behavior of the quadrupole ellipsoid tensor explains the strong mode-dependent autodetachment rate. Meanwhile, the nonadiabatic transition of the excess electron into the valence orbital can result in stable anion formation or immediate chemical bond rupture. In the DBS of ortho-, meta-, or para-iodophenoxide, the transformation of the loosely bound excess electron into the πσ* antibonding orbital occurs to give I–as a final fragment. The fragmentation mediated by DBS occurs competitively with the concomitant autodetachment, paving a new way of the reaction control by tuning the quantum-mechanical nature of the DBS Feshbach resonance. This experimental observation provides the foremost evidence for the dynamic role of the DBS as a doorway into anion chemistry, such as DEA. The ponderomotive force on the electron in the nonvalence orbital has been demonstrated for the first time in a strong optical field, giving great promise for the manipulation of polyatomic molecules in terms of the spatial location, as well as the AC-Stark control of the chemical reaction.
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- 2022
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26. Effect of Molecular Structure of Photoswitchable Surfactant on Light-Responsive Shape Transition of Block Copolymer Particles
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Kim, Jinwoo, Lee, Young Jun, Ku, Kang Hee, and Kim, Bumjoon J.
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Photoactive shape-changing particles offer a promising platform for smart materials with tunable properties at high spatiotemporal resolutions. Herein, a series of spiropyran-based surfactants with different alkyl spacer lengths are developed to achieve photoactive, shape-changing particles through confined self-assembly of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) within an evaporative emulsion. The length of the alkyl chain spacer between the spiropyran headgroup and ionic chain-end is modulated from hexyl to ethyl decanoate to provide surfactants with tunable amphiphilicity. Under UV light, the hydrophilic ring-opened merocyanine surfactants produce onion-like microspheres with a P4VP surface. Conversely, by exposure to visible light, the ring-closure reaction of the spiropyran moieties shifts their hydrophobicity and yields striped ellipsoids with axially stacked PS and P4VP blocks. This sphere-to-ellipsoid transition is observed only for surfactants that contain spacers longer than or equal to octyl. The effects of photoswitchable surfactants on their interfacial properties and corresponding morphological evolution of the particles are investigated to elucidate the mechanism of the shape transition of the photoactive particles.
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- 2022
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27. Experimental Observation of the Resonant Doorways to Anion Chemistry: Dynamic Role of Dipole-Bound Feshbach Resonances in Dissociative Electron Attachment
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Kang, Do Hyung, Kim, Jinwoo, Eun, Han Jun, and Kim, Sang Kyu
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Anion chemical dynamics of autodetachment and fragmentation mediated by the dipole-bound state (DBS) have been thoroughly investigated in a state-specific way by employing the picosecond time-resolved or the nanosecond frequency-resolved spectroscopy combined with the cryogenically cooled ion trap and velocity-map imaging techniques. For the ortho-, meta-, or para-iodophenoxide anion (o-, m-, or p-IPhO–), the C–I bond rupture occurs via the nonadiabatic transition from the DBS to the nearby valence-bound states (VBS) of the anion where the vibronic coupling into the S1(πσ*) state (repulsive along the C–I bond extension coordinate) should be largely responsible. Dynamic details are governed by the isomer-specific nature of the potential energy surfaces in the vicinity of the DBS–VBS curve crossings, as manifested in the huge different chemical reactivity of o-, m-, or p-IPhO–. It is confirmed here that the C–I bond dissociation is mediated by DBS resonances, providing the foremost evidence that the metastable DBS plays the critical role as the doorway into the anion chemistry especially of the dissociative electron attachment (DEA). The fragmentation channel is dominant when it is mediated by the DBS resonances located below the electron-affinity (EA) threshold, whereas it is kinetically adjusted by the competitive autodetachment when the DBS resonances above EA convey the electron to the valence orbitals. The product yield of the C–I bond cleavage is strongly mode-dependent as the rate of the concomitant autodetachment is much influenced by the characteristics of the individual vibrational modes, paving a new way of the reaction control of the anion chemistry.
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- 2022
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28. A comparative study of the effects of low and high uncertainty avoidance on continuance behavior
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Kim, Hak Jin, Choi, Hun, and Kim, Jinwoo
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Information technology ,Wireless voice/data service ,Motivation (Psychology) -- Research -- Usage ,Information technology -- Research -- Usage ,Wireless communication systems -- Services - Abstract
This study examines the effects of uncertainty avoidance (UA) at the individual level on continuance behavior in the domain of mobile data services (MDS). It proposes a research model for post-expectation factors and continuance behavior that considers the moderating effect of UA, and verifies the model with online survey data gathered in Korea and Hong Kong. Post-expectation factors are classified as either intrinsic or extrinsic motivational factors, while respondents are classified according to their propensities into low-UA and high-UA groups. The results indicate that UA has substantial effects not only on the mean values of the post- expectation factors studied but also on the strength of those factors' impact on satisfaction and continuance intention. The effects of intrinsic motivational factors on satisfaction and continuance intention are stronger for the high-UA group than for the low-UA group. In contrast, the effects of extrinsic motivational factors are generally stronger for the low-UA group. Keywords: Continuance Behavior, Extrinsic Motivation, Intrinsic Motivation, Mobile Data Services, Uncertainty Avoidance, INTRODUCTION The rapid development of information communication technology (ICT) has spawned a variety of new products and services for business and communication among which users may select according to their [...]
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- 2010
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29. Design-oriented new product development: LG Electronics' Chocolate Phone illustrates what it takes to be successful
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Jang, Seongkeun, Yoon, Yongki, Lee, Inseong, and Kim, Jinwoo
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LG Electronics Inc. -- Achievements and awards -- Management ,Consumer electronics industry -- Achievements and awards ,Product development ,Electronics industry -- Achievements and awards ,Business, general ,Business ,Engineering and manufacturing industries ,Consumer electronics industry ,Company business management ,Time to market ,Electronics industry ,Management ,Achievements and awards - Abstract
OVERVIEW: There are two approaches to reflecting a customer's point of view in new product development (NPD). One is a customer-following approach that utilizes expressed consumer needs. The other is a customer-leading approach that focuses on consumers' latent needs. Currently, the number of customer-leading approaches is increasing rapidly through design-oriented NPD. This case study of LG Electronics' Chocolate Phone reveals a market-oriented frame of mind. From a design point of view, it is important to select talented designers and combine them with market insight and communication skills. From a development perspective, strong technological capabilities, optimization of design functions, and strong managerial support are all central to success. From a marketing point of view, key factors include finding outside marketing professionals and gathering ideas from the outside. Finally, .from an organizational perspective, it is important to share the design concept among related departments and to change engineering-oriented thinking to a market-oriented frame of mind. KEY CONCEPTS: design, new product development, key success factors, customer-following, customer-leading., Attaching high value to outward appearance is pervasive in Korean society. New words such as Ullzzang (good looking faces) and Momzzang (hot bodies) are being coined continuously, and the societal [...]
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- 2009
30. Optical efficiency of scintillator-coupled photodiode linear arrays for X-ray cargo-container inspection
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Park, Jiwoong, Kim, Jinwoo, Lim, Chang Hwy, and Kim, Ho Kyung
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A scintillator-coupled photodiode linear array is typically used to produce scanned images for cargo-container inspection in combination with a megavoltage X-ray beam. The optical efficiency of the linear detector array was investigated for detector design using the Monte Carlo (MC) technique. The simple MC geometry consists of 15 rectangular parallelepiped blocks arranged regularly in parallel to the long side, below which are an optical glue layer, photodiode passivation layer, and active photodiode layer. A reflection layer surrounding the scintillation pixels is also considered in the geometry. For an isotropic generation of light photons at the center of the scintillator in the middle of the 15-channel array, we determined the light-collection efficiency at the photodiode layer, the crosstalk (the leakage of optical photons to neighboring pixels), and the optical spreading or line-spread function (LSF). The MC simulations revalidate that the refractive index of optical glue should be between those of the passivation layer and the scintillator. The use of a reflector is effective for reducing the crosstalk and enhancing the LSF performance. Using aluminum foil as a reflection material for the cadmium tungstate scintillator (the typical design for megavoltage container inspection systems) could be a poor design choice in terms of the light-collection efficiency and the LSF performance.
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- 2022
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31. Fully controllable time-bin entangled states distributed over 100-km single-mode fibers
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Kim, Jinwoo, Park, Jiho, Kim, Hong-Seok, Kim, Guhwan, Kim, Jin Tae, Park, Jaegyu, Moon, Kiwon, Kwak, Seung-Chan, Kim, Min-su, and Ju, Jung Jin
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Quantum networks that can perform user-defined protocols beyond quantum key distribution will require fully controllable entangled quantum states. To expand the available space of generated time-bin entangled states, we demonstrate a time-bin entangled photon source that produces qubit states |ψ〉=α|00〉+β|11〉with fully controllable phase and amplitudes. Eight different two-photon states have been selected and prepared from arbitrary states on the reduced two-qubit Bloch sphere. The photon pairs encoded in the time-bin scheme were generated at 2.4 MHz with a visibility of V=0.9475±0.0016, with a violation of the CHSH Bell’s inequality by 197 standard deviations. After entanglement distribution over 100 km of single-mode fibers, we obtained a visibility of V=0.9541±0.0113with a violation of the CHSH Bell’s inequality by 6 standard deviations. The prepared states had an average fidelity of 0.9540±0.0016at the source and an average fidelity of 0.9353−0.0209+0.0100after entanglement distribution, which shows that the quantum states generated by our time-bin entangled photon source can be fully controlled potentially to a level applicable to long-distance advanced quantum network systems.
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- 2024
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32. A Deep Motion Sickness Predictor Induced by Visual Stimuli in Virtual Reality.
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Kim, Jinwoo, Oh, Heeseok, Kim, Woojae, Choi, Seonghwa, Son, Wookho, and Lee, Sanghoon
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- *
MOTION sickness , *VISUAL perception , *VIRTUAL reality , *DEEP learning , *SIMULATOR sickness , *USER experience - Abstract
In a virtual reality (VR) environment, where visual stimuli predominate over other stimuli, the user experiences cybersickness because the balance of the body collapses due to self-motion. Accordingly, the VR experience is accompanied by unavoidable sickness referred to as visually induced motion sickness (VIMS). In this article, our primary purpose is to simultaneously estimate the VIMS score by referring to the content and calculate the temporally induced VIMS sensitivity. To seek our goals, we propose a novel architecture composed of two consecutive networks: 1) neurological representation and 2) spatiotemporal representation. In the first stage, the network imitates and learns the neurological mechanism of motion sickness. In the second stage, the significant feature of the spatial and temporal domains is expressed over the generated frames. After the training procedure, our model can calculate VIMS sensitivity for each frame of the VR content by using the weakly supervised approach for unannotated temporal VIMS scores. Furthermore, we release a massive VR content database. In the experiments, the proposed framework demonstrates excellent performance for VIMS score prediction compared with existing methods, including feature engineering and deep learning-based approaches. Furthermore, we propose a way to visualize the cognitive response to visual stimuli and demonstrate that the induced sickness tends to be activated in a similar tendency, as done in clinical studies. [ABSTRACT FROM AUTHOR]
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- 2022
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33. Deep laser microscopy using optical clearing by ultrasound-induced gas bubbles
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Kim, Haemin, Youn, Sangyeon, Kim, Jinwoo, Park, Sunghun, Lee, Moonhwan, Hwang, Jae Youn, and Chang, Jin Ho
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Although laser scanning microscopy is a pivotal imaging tool in biomedical research, optical scattering from tissue limits the depth of the imaging. To overcome this limitation, we propose a scheme called ultrasound-induced optical clearing microscopy, which makes use of temporary, localized optical clearing based on ultrasound-induced gas bubbles. In this method, bubbles are generated by high-intensity pulsed ultrasound at a desired depth and subsequently maintained by low-intensity continuous ultrasound during imaging. As a result, optical scattering and unwanted changes in the propagation direction of the incident photons are minimized in the bubble cloud, and thus the laser can be tightly focused at a deeper imaging plane. Through phantom and ex vivo experiments, we demonstrate that ultrasound-induced optical clearing microscopy is capable of increasing the imaging depth by a factor of six or more, while the resolution is similar to that of conventional laser scanning microscopy.
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- 2022
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34. Modulated model predictive current control of HERIC AFE converter equipped with LCL filter
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Kang, Minju, Kim, Jinwoo, Han, Sanghun, Cho, Younghoon, and Lee, Eunsoo
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This paper proposes a modulated model predictive control (MMPC) of a highly efficient and reliable inverter concept (HERIC) active front end (AFE) converter equipped with an LCL filter. The proposed method is based on the model predictive control (MPC) concept and obtains the optimized duty cycle by using three-level switching states which can be implemented in the HERIC converter. By doing so, the AFE converter achieves fast and precise current control. In addition, the obtained duty cycle is not limited to the polarity of the grid voltage, so it is possible to track the current reference more accurately near the zero-crossing points. The first-order approximation model of the LCL filter is derived to simplify the controller design process with the proposed MMPC. After that, the MMPC algorithm is adopted based on this simplified model in the single-phase system. The switching pattern of the HERIC topology is also proposed considering the MMPC under changing polarity of the duty cycle. To verify the performance of the proposed scheme, a 3 kW HERIC AFE converter was built and tested. Both simulation and experimental results demonstrate that the proposed scheme not only improves total harmonic distortion, but also achieves a fast-tracking performance.
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- 2022
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35. Improvement of osseointegration efficacy of titanium implant through plasma surface treatment
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Lee, Hyungyu, Jeon, Hyun Jeong, Jung, Ara, Kim, Jinwoo, Kim, Jun Young, Lee, Seung Hun, Kim, Hosu, Yeom, Moon Seop, Choe, Wonho, Gweon, Bomi, and Lim, Youbong
- Abstract
A novel plasma treatment source for generating cylindrical plasma on the surface of titanium dental implants is developed herein. Using the titanium implant as an electrode and the packaging wall as a dielectric barrier, a dielectric barrier discharge (DBD) plasma was generated, allowing the implant to remain sterile. Numerical and experimental investigations were conducted to determine the optimal discharge conditions for eliminating hydrocarbon impurities, which are known to degrade the bioactivity of the implant. XPS measurement confirmed that plasma treatment reduced the amount of carbon impurities on the implant surface by approximately 60%. Additionally, in vitro experiments demonstrated that the surface treatment significantly improved cell adhesion, proliferation, and differentiation. Collectively, we proposed a plasma treatment source for dental implants that successfully removes carbon impurities and facilitate the osseointegration of SLA implants.
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- 2022
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36. Light-Active, Reversibly Shape-Shifting Block Copolymer Particles Using Photo-switchable Au Nanoparticle Surfactants
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Kwon, Seung Ho, Xu, Meng, Kim, Jinwoo, Kim, Eun Ji, Lee, Young Jun, Jang, Se Gyu, Yun, Hongseok, and Kim, Bumjoon J.
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Dynamic particles with switchable shapes in response to light have attracted great interest to develop programmable smart materials with superior spatial and temporal resolution. Herein, a facile strategy for light-responsive, shape-changing block copolymer (BCP) particles is developed. Key to this strategy is the design of azobenzene-grafted Au nanoparticles (Au@Azo NPs) as photoswitchable surfactants through photoisomerization of Azo ligands. Under visible light, onion-like polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) BCP particles with PS outer layer form due to the nonpolar nature of trans-Azo ligands, whereas the isomerization to polar cis-Azo surfactants with UV irradiation transforms these spheres into ellipsoids with both PS and P2VP exposed on their surfaces. This light-driven shape change is robust and reversible over multiple irradiation cycles. The reversible shape evolution between spherical and ellipsoidal BCP particles induced by photoactive Au@Azo NP surfactants is elucidated using a cryogenic electron microscope. Furthermore, light-dependent fluorescence and shape of the BCP particles are successfully demonstrated, enabling the visualization of particle shape into an optical signal.
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- 2021
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37. Photoswitchable Surfactant-Driven Reversible Shape- and Color-Changing Block Copolymer Particles
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Kim, Jinwoo, Yun, Hongseok, Lee, Young Jun, Lee, Junhyuk, Kim, Shin-Hyun, Ku, Kang Hee, and Kim, Bumjoon J.
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Polymer particles that switch their shape and color in response to light are of great interest for the development of programmable smart materials. Herein, we report block copolymer (BCP) particles with reversible shapes and colors activated by irradiation with ultraviolet (UV) and visible lights. This shape transformation of the BCP particles is achieved by a spiropyran-dodecyltrimethylammoium bromide (SP-DTAB) surfactant that changes its amphiphilicity upon photoisomerization. Under UV light (365 nm) irradiation, the hydrophilic ring-opened merocyanine form of the SP-DTAB surfactant affords the formation of spherical, onion-like BCP particles. In contrast, when exposed to visible light, surfactants with the ring-closed form yield prolate or oblate BCP ellipsoids with axially stacked nanostructures. Importantly, the change in BCP particle morphology between spheres and ellipsoids is reversible over multiple UV and visible light irradiation cycles. In addition, the shape- and color-switchable BCP particles are integrated to form a composite hydrogel, demonstrating their potential as high-resolution displays with reversible patterning capabilities.
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- 2021
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38. Predictive and prognostic roles of electrical cardiometry in noninvasive assessments of community-acquired pneumonia patients with dyspnoea
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Gho, Kyungil, Woo, Seon Hee, Lee, Sang Moog, Park, Ki Cheol, Park, Gyeong Nam, Kim, Jinwoo, and Hong, Sungyoup
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Thoracic impedance monitoring able to detect pneumonia in the very early phase of emerging infiltration prior the patient developed remarkable clinical symptoms. However, no studies have yet been conducted on the usefulness of predicting pneumonia patient outcomes with parameters from electrical cardiometry. In the present study, we evaluated whether parameters measured by electrical cardiometry can predict clinical outcomes including mortality and length of hospital stay in patients with community-acquired pneumonia in the emergency department. Demographic, clinical and laboratory data were collected from enrolled patient. Electrical cardiometry monitoring was done with a portable electrical cardiometry device connected to the body surface sensor. The continuous data from electrical cardiometry were recorded, and parameters were stored on the electrical cardiometry device automatically and then the data were downloaded for further analysis. Thoracic fluid content has shown to be significantly higher in the intensive care unit admission group and in the death group. Expired patients had higher value of thoracic fluid content at emergency department admission. From a receiver operating characteristics curve analysis, thoracic fluid content presented fair AUC values of 0.72 (95% confidence interval, 0.71–0.74) and 0.73 (0.62–0.82) for prediction of 28-day mortality and intensive care unit admission. Arterial partial pressure of oxygen (PaO2), the ratio of arterial partial pressure of oxygen to inspired oxygen fraction (PaO2/FiO2ratio) also showed excellent AUC value for prediction of mortality and intensive care unit admission. Electrical cardiometry monitoring indicated new possibility to anticipate prognosis of community-acquired pneumonia patient. Increased thoracic fluid content value would relate worse outcome of the patient like mortality and intensive care unit admission. Electrical cardiometry monitoring allows real-time measurements of thoracic fluid content without restraining the patient or invasive catheters.
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- 2021
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39. Stabilization of liquid instabilities with ionized gas jets
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Park, Sanghoo, Choe, Wonho, Lee, Hyungyu, Park, Joo Young, Kim, Jinwoo, Moon, Se Youn, and Cvelbar, Uroš
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Impinging gas jets can induce depressions in liquid surfaces, a phenomenon familiar to anyone who has observed the cavity produced by blowing air through a straw directly above a cup of juice. A dimple-like stable cavity on a liquid surface forms owing to the balance of forces among the gas jet impingement, gravity and surface tension1,2. With increasing gas jet speed, the cavity becomes unstable and shows oscillatory motion, bubbling (Rayleigh instability) and splashing (Kelvin–Helmholtz instability)3,4. However, despite its scientific and practical importance—particularly in regard to reducing cavity instability growth in certain gas-blown systems—little attention has been given to the hydrodynamic stability of a cavity in such gas–liquid systems so far. Here we demonstrate the stabilization of such instabilities by weakly ionized gas for the case of a gas jet impinging on water, based on shadowgraph experiments and computational two-phase fluid and plasma modelling. We focus on the interfacial dynamics relevant to electrohydrodynamic (EHD) gas flow, so-called electric wind, which is induced by the momentum transfer from accelerated charged particles to neutral gas under an electric field. A weakly ionized gas jet consisting of periodic pulsed ionization waves5, called plasma bullets, exerts more force via electrohydrodynamic flow on the water surface than a neutral gas jet alone, resulting in cavity expansion without destabilization. Furthermore, both the bidirectional electrohydrodynamic gas flow and electric field parallel to the gas–water interface produced by plasma interacting ‘in the cavity’ render the surface more stable. This case study demonstrates the dynamics of liquids subjected to a plasma-induced force, offering insights into physical processes and revealing an interdependence between weakly ionized gases and deformable dielectric matter, including plasma–liquid systems.
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- 2021
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40. Emergence of the mobile colistin resistance gene mcr-1in a Leclercia adecarboxylatastrain isolated from wastewater in Seoul
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Kim, Jin Seok, Jeong, Hyo-Won, Jin, Young Hee, Kim, JinWoo, Kim, Jin-ah, Park, Sook Hyun, Yoon, So-Mi, Jung, Sang-Eun, Jang, Jung Im, Kim, Eun Ji, Lee, Jae In, and Lee, Jib-Ho
- Abstract
•Wastewater is a key hotspot for horizontal transfer of antimicrobial resistance.•Leclercia adecarboxylatacarrying mcr-1was isolated from wastewater in Seoul.•The ST3-IncHI2 plasmid can serve as a vehicle for mcr-1dissemination in wastewater.
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- 2024
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41. Oblong-Shaped Piezoelectric Ultrasound Energy Harvester for High-Performance Wireless Power Charging
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Kang, Sungwoo, Shin, Eui-ji, Kim, Juhwan, Kim, Jinwoo, Lee, Eunji, and Chang, Jin Ho
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Wireless power charging for implantable biomedical electronics (IBEs) can potentially eliminate the need for frequent battery-replacement surgeries, ultimately improving patients’ quality of life. Ultrasound wireless power transfer (US-WPT) based on piezoelectric receivers has demonstrated significant potential, particularly for deep-seated IBEs. However, most studies on US-WPT have overlooked the optimization of piezoelectric receiver dimensions relative to transmitted ultrasound beam profiles for maximizing battery-charging efficiency for IBEs. This study revealed that a piezoelectric receiver should have dimensions corresponding to the main lobe width of the transmit beam profile within a focal area. Moreover, its output power should be proportional to the cube of the receiver area. Considering these findings, an oblong-shaped ultrasound transmitter and receiver (OsUTR) was developed for efficient WPT, capable of fully charging commercial batteries. In water, the OsUTR produced an output power per unit area of 246.93mW/cm2, which is 6.588 times higher than that achieved by previously reported methods. This resulted in an average charging rate of 1.64 mC/s, enabling the fully charging of a 30 mAh commercial battery in 1.33h. Experiments with a 50mm thick porcine tissue demonstrated that the OsUTR provided an output voltage and current of 38.4 Vp-pand 103.4 mAp-p, respectively. Consequently, full charging of the battery was successfully achieved in 1.80h. This high-performance OsUTR can enable long-term use of IBEs. This innovation reduces the burden of battery replacement and expands the applicability of implantable devices, driving significant advancements in the IBEs industry.
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- 2024
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42. Light-Responsive Shape- and Color-Changing Block Copolymer Particles with Fast Switching Speed
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Kim, Jinwoo, Park, Jinseok, Jung, Kyunghyun, Kim, Eun Ji, Tan, Zhengping, Xu, Meng, Lee, Young Jun, Ku, Kang Hee, and Kim, Bumjoon J.
- Abstract
Polymer particles capable of dynamic shape changes in response to light have received substantial attention in the development of intelligent multifunctional materials. In this study, we develop a light-responsive block copolymer (BCP) particle system that exhibits fast and reversible shape and color transitions. The key molecular design is the integration of spiropyran photoacid (SPPA) molecules into the BCP particle system, which enables fast and dynamic transformations of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) particles in response to light. The SPPA photoisomerization, induced by 420 nm light irradiation, lowers the pH of the aqueous surroundings from 5.5 to 3.3. The protonated P4VP block substantially increases in domain size from 14 to 39 nm, resulting in significant elongation of the BCP particles (i.e., an increase in the aspect ratio (AR) of the particles from 1.8 to 3.4). Moreover, SPPA adsorbed onto the P4VP surface induces significant changes in the luminescent properties of the BCP particles via photoisomerization of SPPA. Notably, the BCP particles undergo fast, dynamic shape and color transitions within a period of 10 min, maintaining high reversibility over multiple light exposures. Functional dyes are selectively incorporated into different domains of the light-responsive BCP particles to achieve different ranges of color responses. Thus, this study showcases a light-responsive hydrogel display capable of reversible and multicolor photopatterning.
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- 2024
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43. Oxidatively InducedReductive Elimination for Methyl Group Transfer via Isolable Transmetalation Complexes
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Kim, Jinwoo, Jin, Seongho, Kim, Dongwook, and Chang, Sukbok
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Herein, we describe the mechanistic details on the oxidatively induced reductive elimination of isolated methyl iridium and ruthenium metallacycle complexes. It was demonstrated that the otherwise challenging C─C bond formation is indeed facilitated by external oxidation, being enabled under mild conditions. Computational analyses supported the proposed high‐valent pathway, where the energy barrier for reductive elimination significantly decreases upon the metallic oxidation to facilitate the desired C─C bond formation. Detailed aspects on the oxidatively induced reductive elimination from isolated methyl iridium and ruthenium metallacycle species are investigated. The reduction of energy barrier for the reductive elimination process enabled desired C─C bond formation from Ir and Ru metal center under mild conditions.
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- 2021
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44. Merging Two Functions in a Single Rh Catalyst System: Bimodular Conjugate for Light-Induced Oxidative Coupling
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Kim, Jinwoo, Kim, Dongwook, and Chang, Sukbok
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A single molecular rhodium catalyst system (PC2-Cp#RhIII) bearing two functional domains for both photosensitization and C–H carbometalation was designed to enable an intramolecular redox process. The hypothesized charge-transfer species (PC2•–-Cp#RhIV) was characterized by spectroscopic and electrochemical analyses. This photoinduced internal oxidation allows a facile access to the triplet state of the key post-transmetalation intermediate that readily undergoes C–C bond-forming reductive elimination with a lower activation barrier than in its singlet state, thus enabling catalytic C–H arylation and methylation processes.
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- 2020
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45. Ru-Catalyzed Deoxygenative Regioselective C8–H Arylation of Quinoline N-Oxides
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Kim, Jinwoo, Kim, Suhyeon, Kim, Dongwook, and Chang, Sukbok
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Regioselective C–H functionalization on quinolines is of high interest to lead to value-added products. Herein, we describe the development of Ru-catalyzed deoxygenative regioselective C8 arylation of quinoline N-oxides with arylboronic esters. Mechanistic studies revealed that it proceeds in a tandem process of arylation and then deoxygenation, wherein both steps were found to be catalytic with the ruthenium species.
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- 2019
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46. Surface and Interfacial Morphology of Bulk Heterojunction Layers in Organic Solar Cells with Solvent Additive
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Kim, Ajeong, Lee, Jiho, Carnis, Jerome, An, Gukil, Kang, Jinback, Kim, Hyunjung, Kim, Jisu, Shin, Tae Joo, Kim, Jinwoo, and Kim, BongSoo
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We study the surface and interfacial morphology of a bulk heterojunction (BHJ) layer with the solvent additive effect by using the X-ray reflectivity and the grazing incidence X-ray scattering techniques. The BHJ layer consists of poly(4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]thiophene-4,6-diyl) (PTB7) and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) deposited on a poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) coated Si substrate. An interfacial layer with a low electron density is observed between the BHJ and PEDOT:PSS layers, which becomes less distinct when the additive 1,8-diiodooctane (DIO) is added to the film processing solvent. This result indicates that DIO causes PC71BM to become more uniformly distributed throughout the entire BHJ layer. The surface roughness of the BHJ significantly decreases with increasing addition of DIO. The understanding of the surface and interfacial morphology gives an important clue to improving the structures and efficiency.
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- 2019
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47. Light-Responsive, Shape-Switchable Block Copolymer Particles
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Lee, Junhyuk, Ku, Kang Hee, Kim, Jinwoo, Lee, Young Jun, Jang, Se Gyu, and Kim, Bumjoon J.
- Abstract
A robust strategy is developed for preparing light-responsive block copolymer (BCP) particles in which shape and color can be actively controlled with high spatial and temporal resolution. The key to achieving light-responsive shape transitions of BCP particles is the design and synthesis of surfactants containing light-active groups (i.e., nitrobenzyl esters and coumarin esters) that modulate the amphiphilicity and interfacial activity of the surfactants in response to light of a specific wavelength. These light-induced changes in surfactant structure modify the surface and wetting properties of BCP particles, affording both shape and morphological transitions of the particles, for example from spheres with an onion-like inner morphology to prolate or oblate ellipsoids with axially stacked nanostructures. In particular, wavelength-selective shape transformation of the BCP particles can be achieved with a mixture of two light-active surfactants that respond to different wavelengths of light (i.e., 254 and 420 nm). Through the use of light-emitting, photoresponsive surfactants, light-induced changes in both color and shape are further demonstrated. Finally, to demonstrate the potential of the light-triggered shape control of BCP particles in patterning features with microscale resolution, the shape-switchable BCP particles are successfully integrated into a patterned, free-standing hydrogel film, which can be used as a portable, high-resolution display.
- Published
- 2019
- Full Text
- View/download PDF
48. The effect of ambiguous visual stimuli on creativity in design idea generation
- Author
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Jang, Sun Hee, Oh, Byungkeun, Hong, Sukil, and Kim, Jinwoo
- Abstract
ABSTRACTThe purpose of the present study is to investigate the effect of visual stimuli on creativity for generating ideas among designers. A survey with design students was conducted in this investigation to extract visual stimuli from the sub-symbolic domain (vague stimuli), visual stimuli from the symbolic domain (definite stimuli), and visual stimuli between the two domains (ambiguous stimuli). Subsequently, a conceptual combination experiment was conducted using selected stimuli to examine the effects of ambiguous visual stimuli on creativity to generate ideas among designers. The results suggest that in individual working environments, dissimilar concept pairs fostered higher elaboration when ambiguous stimuli were present, whereas similar concept pairs fostered higher elaboration when vague stimuli were presented. It was further suggested that in group working environments, vague stimuli result in higher abstractness when dissimilar concept pairs are used, whereas ambiguous stimuli result in higher abstractness when similar concept pairs were used.
- Published
- 2019
- Full Text
- View/download PDF
49. Oxidatively Induced Reductive Elimination: Exploring the Scope and Catalyst Systems with Ir, Rh, and Ru Complexes
- Author
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Kim, Jinwoo, Shin, Kwangmin, Jin, Seongho, Kim, Dongwook, and Chang, Sukbok
- Abstract
Direct conversion of C–H bonds into C–C bonds is a promising alternative to the conventional cross-coupling reactions, thus giving rise to a wide range of efficient catalytic C–H functionalization reactions. Among the elementary stages in the catalytic C–C bond formation, reductive elimination constitutes a key step of the catalytic cycle, and, therefore, extensive studies have been made to facilitate this process. In this regard, oxidation on the metal center of a post-transmetalation intermediate would be an appealing approach. Herein, we have explored the substrate scope, catalyst systems, and oxidation tools to prove that the oxidatively induced reductive elimination(ORE) plays a critical role in the product-releasing C–C bond formation. Notably, we have demonstrated that ORE broadly operates with a series of half-sandwich d6Ir(III)-, Rh(III)-, and Ru(II)-aryl complexes. We have described that the metal center oxidation of the isolable post-transmetalation intermediates by means of chemical- or electro-oxidation can readily deliver the desired arylated products upon reductive elimination even at ambient temperature. Computational studies delineated the thermodynamics of the reductive elimination, where the activation barriers are shown to be significantly reduced upon increasing the oxidation states of the intermediates. We were also successful in corroborating this ORE in the corresponding Rh-methylcomplex. In addition, catalytic conditions were optimized to incorporate this mechanistic understanding into the Ir-, Rh-, and Ru-catalyzed C–C bond formations under mild conditions.
- Published
- 2019
- Full Text
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50. Mechanistic Study on the Shape Transition of Block Copolymer Particles Driven by Length-Controlled Nanorod Surfactants
- Author
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Ku, Kang Hee, Ryu, Ji Ho, Kim, Jinwoo, Yun, Hongseok, Nam, Chongyong, Shin, Jae Man, Kim, Youngkwon, Jang, Se Gyu, Lee, Won Bo, and Kim, Bumjoon J.
- Abstract
Interface engineering of evaporative emulsion droplets containing block copolymers (BCPs) provides an effective route to generate nonspherical particles. Here, we demonstrate the impact of length-controlled nanorods (NRs) on the interfacial properties of BCP emulsions to produce anisotropic BCP particles. A series of lamellae- and cylinder-forming polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) and a series of NRs with different lengths (l) are coassembled, and selective arrangement of the NRs on the P4VP domain at the particle surface enables the production of striped football (prolate) and convex lens-shaped (oblate) particles. In particular, the ratio of the NR length to the size of the NR-hosting domain (l/L), which is varied from 0.07 to 3.60, is the key parameter in determining the location of the NRs in the BCP particles as well as the final particle shape. The oblate particles are generated only in the range of 0.36 ≤ l/L≤ 0.96, whereas the prolate particles are produced for much wider range of l/L≥ 0.83 without upper limit. This difference is attributed to larger entropic penalty for the NRs confined within the P4VP cylinders than the entropic penalty for those within the lamellae. To better understand and support our experimental observations, we performed dissipative particle dynamics simulation and calculated the free energy for the NR/BCP assembly within the emulsion droplets.
- Published
- 2018
- Full Text
- View/download PDF
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