430 results on '"Jeong Ik Lee"'
Search Results
2. Comparative study of constitutive relations implemented in RELAP5 and TRACE – Part I: Methodology & wall friction
- Author
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Sung Gil Shin and Jeong Ik Lee
- Subjects
Nuclear Energy and Engineering - Published
- 2022
3. Design study of heat transport and power conversion systems for micro molten salt reactor
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In Woo Son, Sungwook Choi, Yongju Jeong, and Jeong Ik Lee
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Fuel Technology ,Nuclear Energy and Engineering ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology - Published
- 2022
4. 59‐2: Invited Paper: High‐Color‐Gamut Organic Light‐Emitting Diode Microdisplay for Augmented‐Reality/Virtual‐Reality Devices
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Dae Hyun Ahn, Jin-Wook Shin, Kukjoo Kim, Chul Woong Joo, Hyunsu Cho, Sukyung Choi, Byoung-Hwa Kwon, Gi Heon Kim, Chun-Won Byun, Nam Sung Cho, Jeong-Ik Lee, Soobin Sim, Jinha Ryu, Hyunkoo Lee, Hyoc Min Youn, Young Jae An, Jin Sun Kim, Jeong Hwan Lee, Hokwon Kim, Minseok Kim, and Chan-mo Kang
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Organic Chemistry ,Biochemistry - Published
- 2022
5. Comparative study of constitutive relations implemented in RELAP5 and TRACE – Part II: Wall boiling heat transfer
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Jeong Ik Lee and Sung Gil Shin
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Trace (semiology) ,Materials science ,Nuclear Energy and Engineering ,Metallurgy ,Boiling heat transfer - Published
- 2022
6. Organic light-emitting diode (OLED) frontplanes for high-resolution microdisplay with high color gamut (Conference Presentation)
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Hyunsu Cho, Chan-mo Kang, Jin-Wook Shin, Sukyung Choi, Chul Woong Joo, Byoung-Hwa Kwon, Kukjoo Kim, Dae Hyun Ahn, Gi Heon Kim, Chun-Won Byun, Nam Sung Cho, Jeong-Ik Lee, Soobin Sim, Jinha Ryu, Hyunkoo Lee, Hyoc Min Youn, Young Jae An, and Jin Sun Kim
- Published
- 2023
7. Assessment of thermal fatigue induced by dryout front oscillation in printed circuit steam generator
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Jin Su Kwon, Sang Ji Kim, Sung Gil Shin, Doh Hyeon Kim, and Jeong-Ik Lee
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Materials science ,Nuclear Energy and Engineering ,law ,Superheated steam ,Boiling ,Pressurized water reactor ,Evaporation ,Boiler (power generation) ,Mechanics ,Heat transfer coefficient ,Leidenfrost effect ,Pressure vessel ,law.invention - Abstract
A printed circuit steam generator (PCSG) is being considered as the component for pressurized water reactor (PWR) type small modular reactor (SMR) that can further reduce the physical size of the system. Since a steam generator in many PWR-type SMR generates superheated steam, it is expected that dryout front oscillation can potentially cause thermal fatigue failure due to cyclic thermal stresses induced by the transition in boiling regimes between convective evaporation and film boiling. To investigate the fatigue issue of a PCSG, a reference PCSG is designed in this study first using an in-house PCSG design tool. For the stress analysis, a finite element method analysis model is developed to obtain the temperature and stress fields of the designed PCSG. Fatigue estimation is performed based on ASME Boiler and pressure vessel code to identify the major parameters influencing the fatigue life time originating from the dryout front oscillation. As a result of this study, the limit on the temperature difference between the hot side and cold side fluids is obtained. Moreover, it is found that the heat transfer coefficient of convective evaporation and film boiling regimes play an essential role in the fatigue life cycle as well as the temperature difference.
- Published
- 2022
8. Evaluation of off-design scaling methods of supercritical CO2 compressor with experimental data
- Author
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Yongju Jeong, Seong Kuk Cho, In Woo Son, and Jeong Ik Lee
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General Energy ,Mechanical Engineering ,Building and Construction ,Electrical and Electronic Engineering ,Pollution ,Industrial and Manufacturing Engineering ,Civil and Structural Engineering - Published
- 2023
9. Evaluation of various large-scale energy storage technologies for flexible operation of existing pressurized water reactors
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Jin Young Heo, Seung Hwan Oh, Jeong-Ik Lee, So Young Lee, Jung Hwan Park, Yong Jae Chae, Nirmal Gnanapragasam, and Ju Yeon Lee
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Rankine cycle ,Energy storage system ,020209 energy ,Cryogenic energy storage ,02 engineering and technology ,Thermal energy storage ,Energy storage ,030218 nuclear medicine & medical imaging ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,law ,Steam turbine ,Concentrated solar power ,0202 electrical engineering, electronic engineering, information engineering ,Process engineering ,Liquid air energy storage ,System integration ,business.industry ,TK9001-9401 ,Pressurized water reactor ,Compressed CO2 energy storage ,Nuclear power ,Nuclear plant ,Nuclear Energy and Engineering ,Nuclear engineering. Atomic power ,Environmental science ,business - Abstract
The lack of plant-side energy storage analysis to support nuclear power plants (NPP), has setup this research endeavor to understand the characteristics and role of specific storage technologies and the integration to an NPP. The paper provides a qualitative review of a wide range of configurations for integrating the energy storage system (ESS) to an operating NPP with pressurized water reactor (PWR). The role of ESS technologies most suitable for large-scale storage are evaluated, including thermal energy storage, compressed gas energy storage, and liquid air energy storage. The methods of integration to the NPP steam cycle are introduced and categorized as electrical, mechanical, and thermal, with a review on developments in the integration of ESS with an operating PWR. By adopting simplified off-design modeling for the steam turbines and heat exchangers, the results show the performance of the PWR steam cycle changes with respect to steam bypass rate for thermal and mechanical storage integration options. Analysis of the integrated system characteristics of proposed concepts for three different ESS suggests that certain storage technologies could support steady operation of an NPP. After having reviewed what have been accomplished through the years, the research team presents a list of possible future works.
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- 2021
10. Exceptional Repositioning of Dog Dewormer: Fenbendazole Fever
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Tania Sultana, Umair Jan, Hyunsu Lee, Hyejin Lee, and Jeong Ik Lee
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Microbiology (medical) ,General Medicine ,Molecular Biology ,Microbiology - Abstract
Fenbendazole (FZ) is a benzimidazole carbamate drug with broad-spectrum antiparasitic activity in humans and animals. The mechanism of action of FZ is associated with microtubular polymerization inhibition and glucose uptake blockade resulting in reduced glycogen stores and decreased ATP formation in the adult stages of susceptible parasites. A completely cured case of lung cancer became known globally and greatly influenced the cancer community in South Korea. Desperate Korean patients with cancer began self-administering FZ without their physician’s knowledge, which interfered with the outcome of the cancer treatment planned by their oncologists. On the basis of presented evidence, this review provides valuable information from PubMed, Naver, Google Scholar, and Social Network Services (SNS) on the effects of FZ in a broad range of preclinical studies on cancer. In addition, we suggest investigating the self-administration of products, including supplements, herbs, or bioactive compounds, by patients to circumvent waiting for long and costly FZ clinical trials.
- Published
- 2022
11. Cover Image, Volume 46, Issue 11
- Author
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In Woo Son, Sungwook Choi, Yongju Jeong, and Jeong Ik Lee
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Fuel Technology ,Nuclear Energy and Engineering ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology - Published
- 2022
12. 30‐1: Invited Paper: High Aspect Ratio OLED Microdisplay with Pin Mirror Lens for Small Form Factor AR Devices
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Soon-gi Park, Minseok Kim, Sang Hyun Park, Hyunsu Cho, Hokwon Kim, Jeonghun Ha, Jongsoo Lee, Sang Tae Kim, Ara Cho, Jeong Hwan Lee, Jiyong Park, Chan-mo Kang, Yu Bin Im, Hyunkoo Lee, SeungJoon Kwon, Sukyung Choi, Byoung-Hwa Kwon, Nam Sung Cho, Jeong-Ik Lee, Chun-Won Byun, Seung No Lee, Jung-Sik Koo, Jaehyeok Kim, Jin-Wook Shin, and Youngjoon Kim
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Lens (optics) ,Optics ,Materials science ,law ,business.industry ,OLED ,Field of view ,business ,law.invention ,Small form factor - Published
- 2021
13. High aspect ratio microdisplay and thin optical component for glass-like AR devices
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Seung No Lee, Hyunkoo Lee, Ara Cho, Byoung-Hwa Kwon, Chun-Won Byun, Hyunsu Cho, Sang Hyun Park, Minseok Kim, Jongsoo Lee, Jaehyeok Kim, Hokwon Kim, Sukyung Choi, Youngjoon Kim, Jeong Hwan Lee, Jeong-Ik Lee, Yu Bin Im, Chan-mo Kang, Jin-Wook Shin, Jeonghun Ha, Nam Sung Cho, Soon-gi Park, and Sang Tae Kim
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010302 applied physics ,Computer engineering. Computer hardware ,Materials science ,oled ,business.industry ,ar device ,ar/vr ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Wide field ,Small form factor ,TK7885-7895 ,oled microdisplay ,Component (UML) ,0103 physical sciences ,OLED ,Optoelectronics ,General Materials Science ,Augmented reality ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,Diode - Abstract
Organic light-emitting diode (OLED) microdisplays have attracted much attention as displays for small form factor augmented reality (AR) devices. To realize glass-like thin and wide field of view (FoV) AR devices, we designed a display module with a high aspect ratio microdisplay and a thin optical component. For the high aspect ratio microdisplay, we developed the color OLED microdisplay with a 32:9 aspect ratio and a 0.8-inch diagonal ∼2,490-ppi CMOS backplane. To express color and reduce optical crosstalk, we fabricated the color filter (C/F) patterning directly on the white OLED. We also developed a pin mirror lens with 11 pin mirrors to improve the optical efficiency and quality with a thin lens. By combining the microdisplay with LetinAR’s pin mirror lens, we successfully demonstrated an AR device with a wide horizontal FoV of 46° but with a small form factor 4 mm lens.
- Published
- 2021
14. Thermally stable and soft pressure-sensitive adhesive for foldable electronics
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TaekSoo Kim, Woosung Jo, Kihoon Jeong, Young-Sam Park, Jeong-Ik Lee, and Sung Gap Im
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History ,Polymers and Plastics ,General Chemical Engineering ,Environmental Chemistry ,General Chemistry ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2023
15. Superior therapeutic activity of TGF-β-induced extracellular vesicles against interstitial cystitis
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Kwonwoo Song, Ahmed Abdal Dayem, Soobin Lee, Yujin Choi, Kyung Min Lim, Sehee Kim, Jongyub An, Yeokyung Shin, Hyojin Park, Tak-Il Jeon, Soo Bin Jang, Hanbit Bong, Jeong Ik Lee, Geun-Ho Kang, Sejong Kim, Aram Kim, and Ssang-Goo Cho
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Extracellular Vesicles ,Transforming Growth Factor beta ,Anti-Inflammatory Agents ,Cystitis, Interstitial ,Pharmaceutical Science ,Animals ,Mesenchymal Stem Cells - Abstract
Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic disease characterized by incapacitating pelvic pain. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) are considered key mediators of the paracrine action of MSCs and show better biological activities than the parent MSCs, especially in the bladder tissue, which may be unfavorable for MSC survival. Here, we produced MSC-EVs using advanced three-dimensional (a3D) culture with exogenous transforming growth factor-β3 (TGF-β3) (T-a3D-EVs). Treatment with T-a3D-EVs led to significantly enhanced wound healing and anti-inflammatory capacities. Moreover, submucosal layer injection of T-a3D-EVs in chronic IC/BPS animal model resulted in restoration of bladder function, superior anti-inflammatory activity, and recovery of damaged urothelium compared to MSCs. Interestingly, we detected increased TGF-β1 level in T-a3D-EVs, which might be involved in the anti-inflammatory activity of these EVs. Taken together, we demonstrate the excellent immune-modulatory and regenerative abilities of T-a3D-EVs as observed by recovery from urothelial denudation and dysfunction, which could be a promising therapeutic strategy for IC/BPS.
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- 2022
16. Double Repositioning: Veterinary Antiparasitic to Human Anticancer
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Tania Sultana, Umair Jan, and Jeong Ik Lee
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Antiparasitic Agents ,Organic Chemistry ,Drug Repositioning ,Antineoplastic Agents ,General Medicine ,Catalysis ,Computer Science Applications ,Inorganic Chemistry ,Neoplasms ,Quality of Life ,Humans ,Physical and Theoretical Chemistry ,Molecular Biology ,Spectroscopy - Abstract
Drug repositioning, the approach of discovering different uses for existing drugs, has gained enormous popularity in recent years in the anticancer drug discovery field due to the increasing demand for anticancer drugs. Additionally, the repurposing of veterinary antiparasitic drugs for the treatment of cancer is gaining traction, as supported by existing literature. A prominent example is the proposal to implement the use of veterinary antiparasitics such as benzimidazole carbamates and halogenated salicylanilides as novel anticancer drugs. These agents have revealed pronounced anti-tumor activities and gained special attention for “double repositioning”, as they are repurposed for different species and diseases simultaneously, acting via different mechanisms depending on their target. As anticancer agents, these compounds employ several mechanisms, including the inhibition of oncogenic signal transduction pathways of mitochondrial respiration and the inhibition of cellular stress responses. In this review, we summarize and provide valuable information about the experimental, preclinical, and clinical trials of veterinary antiparasitic drugs available for the treatment of various cancers in humans. This review suggests the possibility of new treatment options that could improve the quality of life and outcomes for cancer patients in comparison to the currently used treatments.
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- 2022
17. Effects of carrier solutions on the viability and efficacy of canine adipose-derived mesenchymal stem cells
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Tania Sultana, Ahmed Abdal Dayem, Soo Bin Lee, Ssang-Goo Cho, and Jeong Ik Lee
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Transplantation ,Ringer's Lactate ,General Veterinary ,Heparin ,Veterinary medicine ,Organ Preservation Solutions ,Proliferation ,Cell Differentiation ,Mesenchymal Stem Cells ,Hartmann’s solution ,General Medicine ,5% dextrose solution ,Phosphates ,0.9% saline ,Canine ,Dogs ,Adipose Tissue ,Adipose-derived mesenchymal stem cells ,SF600-1100 ,Animals ,Stemness ,Phosphate-buffered saline ,Cells, Cultured ,Cell Proliferation ,Research Article - Abstract
Background Mesenchymal stem cells (MSCs) have favorable characteristics that render them a potent therapeutic tool. We tested the characteristics of MSCs after temporal storage in various carrier solutions, such as 0.9% saline (saline), 5% dextrose solution (DS), heparin in saline, and Hartmann’s solution, all of which are approved by the U.S. Food and Drug Administration (FDA). Phosphate-buffered saline, which does not have FDA approval, was also used as a carrier solution. We aimed to examine the effects of these solutions on the viability and characteristics of MSCs to evaluate their suitability and efficacy for the storage of canine adipose-derived MSCs (cADMSCs). Results We stored the cADMSCs in the test carrier solutions in a time-dependent manner (1, 6, and 12 h) at 4 °C, and analyzed cell confluency, viability, proliferation, self-renewability, and chondrogenic differentiation. Cell confluency was significantly higher in 5% DS and lower in phosphate-buffered saline at 12 h compared to other solutions. cADMSCs stored in saline for 12 h showed the highest viability rate. However, at 12 h, the proliferation rate of cADMSCs was significantly higher after storage in 5% DS and significantly lower after storage in saline, compared to the other solutions. cADMSCs stored in heparin in saline showed superior chondrogenic capacities at 12 h compared to other carrier solutions. The expression levels of the stemness markers, Nanog and Sox2, as well as those of the MSC surface markers, CD90 and CD105, were also affected over time. Conclusion Our results suggest that MSCs should be stored in saline, 5% DS, heparin in saline, or Hartmann’s solution at 4 °C, all of which have FDA approval (preferable storage conditions: less than 6 h and no longer than 12 h), rather than storing them in phosphate-buffered saline to ensure high viability and efficacy.
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- 2022
18. Radionuclide transport in a long‐term operation supercritical CO 2 ‐cooled direct‐cycle small nuclear reactor
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Seongmin Son, Seong Kuk Cho, Jeong-Ik Lee, Bongseong Oh, and Jinsu Kwon
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Radionuclide ,Nuclear fission product ,Fuel Technology ,Nuclear Energy and Engineering ,Renewable Energy, Sustainability and the Environment ,law ,Nuclear engineering ,Energy Engineering and Power Technology ,Environmental science ,Nuclear reactor ,Supercritical fluid ,law.invention ,Term (time) - Published
- 2020
19. A prototype active-matrix OLED using graphene anode for flexible display application
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Kang Me Lee, Chi-Sun Hwang, Hyunsu Cho, Hyunkoo Lee, Byoung-Hwa Kwon, Chun-Won Byun, Jun-Han Han, Nam Sung Cho, Jin Sung Park, Chan-mo Kang, Himchan Oh, Jin-Wook Shin, Jong-Heon Yang, Jeong-Ik Lee, Jaehyun Moon, O Eun Kwon, Jong Hyuk Yoon, and Chae Seung Jin
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flexible electrode ,lcsh:Computer engineering. Computer hardware ,Materials science ,lcsh:TK7885-7895 ,02 engineering and technology ,01 natural sciences ,law.invention ,law ,0103 physical sciences ,OLED ,General Materials Science ,Electrical and Electronic Engineering ,010302 applied physics ,Graphene ,business.industry ,graphene ,active-matrix oled ,transparent electrode ,021001 nanoscience & nanotechnology ,Anode ,Active matrix ,Flexible display ,organic light-emitting diode (oled) ,Electrode ,Optoelectronics ,0210 nano-technology ,business - Abstract
From the very first time that graphene was used as a transparent electrode for OLED applications, the emergence of active-matrix (AM)-graphene OLED displays has been envisioned. Realizing this expectation, however, turned out to be difficult. Two obstacles are the growth and transfer of a large-area graphene film and the patterning of a graphene film into pixels. To solve these problems, a process of patterning a graphene film without surface contamination was developed. The fabrication of OLED panels by the patterned graphene anode on Gen 2(370 × 470 mm)-sized and flexible substrates was successfully demonstrated. In this work, oxide TFT arrays were combined as a switching backplane, and a pixelated graphene OLED was used as an emissive layer, to realize AM-graphene OLED displays. To explore the technical feasibility of flexible AM-graphene OLED displays, the aforementioned components were formed on a flexible substrate. For commercial-level production, all the processes that were used were chosen to be compatible with the conventional display processes.
- Published
- 2019
20. White organic light-emitting diode (OLED) microdisplay with a tandem structure
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Jeong Hwan Lee, Minseok Kim, Jin-Wook Shin, Sukyung Choi, Chun-Won Byun, Hyunsu Cho, Hokwon Kim, Hyunkoo Lee, Byoung-Hwa Kwon, Nam Sung Cho, Chan-mo Kang, and Jeong-Ik Lee
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010302 applied physics ,Materials science ,lcsh:Computer engineering. Computer hardware ,Tandem ,business.industry ,tandem ,lcsh:TK7885-7895 ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,microdisplay ,Mixed reality ,organic light-emitting diode (oled) ,0103 physical sciences ,white oled ,OLED ,Optoelectronics ,General Materials Science ,Augmented reality ,Electrical and Electronic Engineering ,Operating voltage ,0210 nano-technology ,business - Abstract
Microdisplay is a key technology for realizing augmented reality (AR) and mixed reality (MR) devices, which have attracted much attention of late. Even though the operating voltage in the tandem structure is higher than that in the single structure, 2-stack tandem OLED exhibited 20,000 cd/m2 at 9 V, which is compatible with CMOS circuit driving. Due to its top-emitting geometry with a tandem structure, the OLED device with a well-controlled thickness exhibited a white spectrum with (0.26, 0.26) color coordinates. The pixel density of the fabricated microdisplay panel with a white tandem OLED was about 2350 pixels per inch, and the active area of the panel was 0.7 inch diagonally. The resolution of the panel was 1280 × 1024, corresponding to SXGA, and the maximal luminance was 3,000 cd/m2.
- Published
- 2019
21. Thermal energy storage unit (TESU) design for high round-trip efficiency of liquid air energy storage (LAES)
- Author
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Kyoung Joong Kim, Bokeum Kim, Byeongchang Byeon, Sangkwon Jeong, Jeong Ik Lee, Junghwan Park, and Aqil Jamal
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General Physics and Astronomy ,General Materials Science - Published
- 2022
22. Study on supercritical CO2 critical flow through orifices under power cycle operating conditions
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Jae Jun Lee, Jeong Yeol Baek, and Jeong Ik Lee
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General Chemical Engineering ,Physical and Theoretical Chemistry ,Condensed Matter Physics - Published
- 2022
23. Design Considerations for the Liquid Air Energy Storage System Integrated to Nuclear Steam Cycle
- Author
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Seok Ho Song, Jeong-Ik Lee, and Jin-Young Heo
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Rankine cycle ,Technology ,Power station ,QH301-705.5 ,QC1-999 ,Cryogenic energy storage ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,law.invention ,law ,Liquid air ,Nuclear power plant ,nuclear power ,General Materials Science ,Biology (General) ,Process engineering ,Instrumentation ,QD1-999 ,Fluid Flow and Transfer Processes ,load following operation ,business.industry ,Process Chemistry and Technology ,Physics ,General Engineering ,liquid air energy storage (LAES) ,Nuclear power ,Engineering (General). Civil engineering (General) ,Computer Science Applications ,Power (physics) ,Renewable energy ,Chemistry ,Environmental science ,TA1-2040 ,business - Abstract
A nuclear power plant is one of the power sources that shares a large portion of base-load. However, as the proportion of renewable energy increases, nuclear power plants will be required to generate power more flexibly due to the intermittency of the renewable energy sources. This paper reviews a layout thermally integrating the liquid air energy storage system with a nuclear power plant. To evaluate the performance realistically while optimizing the layout, operating nuclear power plant conditions are used. After revisiting the analysis, the optimized performance of the proposed system is predicted to achieve 59.96% of the round-trip efficiency. However, it is further shown that external environmental conditions could deteriorate the performance. For the design of liquid air energy storage-nuclear power plant integrated systems, both the steam properties of the linked plants and external factors should be considered.
- Published
- 2021
24. Integration Options for Nuclear Steam Cycle Using Liquid Air Energy Storage
- Author
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Jung Hwan Park, Jin Young Heo, Jeong-Ik Lee, and Won Woong Lee
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Rankine cycle ,Waste management ,law ,Environmental science ,Cryogenic energy storage ,Energy storage ,law.invention - Abstract
To facilitate the energy transition, the conventional baseload nuclear power must be equipped with flexibility. By integrating grid-scale energy storage systems to the existing nuclear plants, they can curtail their load to avoid surplus generation. Liquid air energy storage (LAES) has been steadily investigated for their advantages, and this paper suggests an integrated layout using mechanical drive steam turbine and packed bed energy storage systems. Possible options for integration of LAES to the existing nuclear steam cycle are considered. The performance of packed bed storage systems is analyzed using transient modeling, and the results are fed into the overall cycle design using an in-house code. The results of the analysis suggests that the concept can reach up to 45.7–59.8% in round-trip efficiency, under much simplified cycle layout than the reference LAES layouts.
- Published
- 2021
25. CFD simulation of an integrated PCM-based thermal energy storage within a nuclear power plant connected to a grid with constant or variable power demand
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Mohamed Ali, Ahmed K. Alkaabi, and Jeong Ik Lee
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Nuclear and High Energy Physics ,Nuclear Energy and Engineering ,Mechanical Engineering ,General Materials Science ,Safety, Risk, Reliability and Quality ,Waste Management and Disposal - Published
- 2022
26. Metal-Organic Framework as a Functional Analyte Channel of Organic-Transistor-Based Air Pollution Sensors
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Yeong Don Park, Miyeon Kim, Boseok Kang, Jun Hwa Park, Chang Yeon Lee, and Jeong Ik Lee
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Materials science ,Carbonization ,business.industry ,Transistor ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,Active layer ,Organic semiconductor ,chemistry.chemical_compound ,Responsivity ,chemistry ,law ,Optoelectronics ,Polythiophene ,General Materials Science ,Metal-organic framework ,0210 nano-technology ,business ,Zeolitic imidazolate framework - Abstract
Air pollution sensors based on organic transistors have attracted much interest recently; however, the devices suffer from low responsivity and slow response and recovery rates for gas analytes. These shortcomings are attributed to the low charge-carrier mobility of organic semiconductors and to a structural limitation resulting from the use of a thick and continuous active layer. In the present work, we investigated the material properties of a multiscale porous zeolitic imidazolate framework, [Zn(2-methylimidazole)2]n (ZIF-8), and examined its potential as an analyte channel material inserted at an organic-transistor active layer. A series of carbonized zeolitic imidazolate frameworks (ZIFs) were prepared by thermal conversion of ZIF-8 and also studied for comparison. The microstructures, morphologies, and optical/electrical characteristics of polythiophene/ZIF-8 hybrid films were systematically investigated. Organic-transistor-type nitrogen dioxide sensors based on the polythiophene/ZIF-8 hybrid films showed substantially improved sensing properties, including responsivity, response rate, and recovery rate. The electrical conductivity of the carbonized ZIF-8s enhanced the field-effect mobility of the organic transistors; however, the sensing performance was not improved, because of the closed pore structures resulting from the carbonization. These results provide invaluable information and useful insights into the design of transistor-type gas sensors based on organic semiconductor/metal-organic framework hybrid films.
- Published
- 2021
27. Anterior Bridging Bone in a Newly Designed Cage for Lumbar Interbody Fusion: Radiographic and Finite Element Analysis
- Author
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Jeong Ik Lee, Kwang-Sup Song, Hyung-Chul Cho, and Seung-Hwan Chang
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Male ,Bridging (networking) ,Radiography ,Finite Element Analysis ,Computed tomography ,Disability Evaluation ,Lumbar interbody fusion ,medicine ,Humans ,In patient ,Range of Motion, Articular ,Aged ,Mechanical Phenomena ,Orthodontics ,Lumbar Vertebrae ,medicine.diagnostic_test ,business.industry ,Equipment Design ,Middle Aged ,Finite element method ,Internal Fixators ,Spine ,Oswestry Disability Index ,Spinal Fusion ,Treatment Outcome ,Surgery ,Female ,Neurology (clinical) ,Stress, Mechanical ,Cage ,business ,Tomography, X-Ray Computed - Abstract
Objective To evaluate the distribution of multiple anterior bridging bone (ABB) patterns using a newly designed interbody cage with 4 anterior holes that enable communication between the inside and outside of the cage and to estimate its mechanical effect by finite element analysis (FEA). Methods Patients underwent single-level lumbar interbody fusion using ABB cages. Two raters evaluated the distribution patterns of ABB on computed tomography scans 1 year after surgery. We defined the term H-fusion as the presence of complete anterior extracage and intracage bone bridging, with ≥1 ABBs between them. We performed finite element analysis to investigate the effect of ABB on maximal stiffness. Results The study enrolled 98 patients. ABB was most frequently observed in the medial hole of the cages (73.7%). The mean number of ABBs was 3.65, and H-fusion was observed at 135 levels (34%). Postoperative improvement in the Oswestry Disability Index was significantly higher in patients who achieved interbody fusion and H-fusion than in patients who did not. As ABB was added, the increment in the relative maximal stiffness was most affected under flexion and extension forces. Conclusions We observed an average of 3.65 complete ABBs. Finite element analysis demonstrated that ABB could increase the stability in fused segments, especially under flexion and extension stress. Our results suggest that the ABB cage, which allows communicating cross-bridging between inside and outside of the cage, may facilitate a more stable fusion process than a conventionally designed cage.
- Published
- 2021
28. Instability Study of Magnetic Journal Bearing under S-CO2 Condition
- Author
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Seungjoon Baik, Jeong-Ik Lee, and Dokyu Kim
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magnetic bearing ,Computer science ,Test rig ,Magnetic bearing ,Mechanical engineering ,02 engineering and technology ,01 natural sciences ,Instability ,lcsh:Technology ,law.invention ,lcsh:Chemistry ,0203 mechanical engineering ,law ,0103 physical sciences ,General Materials Science ,Instrumentation ,lcsh:QH301-705.5 ,010302 applied physics ,Fluid Flow and Transfer Processes ,supercritical carbon dioxide Brayton cycle (S-CO2 Brayton cycle) ,Bearing (mechanical) ,lcsh:T ,Process Chemistry and Technology ,General Engineering ,Distributed power ,Brayton cycle ,lcsh:QC1-999 ,Computer Science Applications ,instability ,020303 mechanical engineering & transports ,lcsh:Biology (General) ,lcsh:QD1-999 ,lcsh:TA1-2040 ,Levitation ,Reduced cost ,lcsh:Engineering (General). Civil engineering (General) ,lcsh:Physics - Abstract
A supercritical CO2 (S-CO2)-cooled Brayton cycle is under development for distributed power applications for remote regions. In order to successfully develop it, issues of controlling shaft levitation with bearings have to be solved. From several studies, magnetic bearings have been suggested for reliable levitation performance with reduced cost and complexity. However, several studies on magnetic bearing show that instability issues under high-pressure fluid and high-speed operating conditions may exist. The purpose of this research is to provide background for understanding the instability of magnetic bearings under S-CO2 conditions and propose functional requirements of the magnetic bearing. Thus, the rotating shaft with magnetic bearings operating under high pressure fluid was first analyzed. To test the theory, a magnetic bearing test rig was constructed. By comparing experimental data to the analysis results, the analysis results were verified. Therefore, the analysis results can be used for predicting instability in the future and can contribute to the development of better magnetic bearing controllers.
- Published
- 2021
29. Study of critical flow for supercritical CO2 seal
- Author
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Jeong-Ik Lee, Min Seok Kim, Seongmin Son, Bong Seong Oh, and Seong Jun Bae
- Subjects
Fluid Flow and Transfer Processes ,Materials science ,020209 energy ,Mechanical Engineering ,Nozzle ,Flow (psychology) ,02 engineering and technology ,Mechanics ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Labyrinth seal ,Seal (mechanical) ,Supercritical fluid ,0202 electrical engineering, electronic engineering, information engineering ,Two-phase flow ,0210 nano-technology ,Choked flow ,Body orifice - Abstract
Supercritical CO2 (S-CO2) has the potential to be used as the working fluid in a power cycle since S-CO2 shows a density value high as its liquid phase while the viscosity value remains closer to its gaseous phase. Thus, it requires much less work to compress due to its low compressibility as well as relatively small flow resistance. However, the S-CO2 leakage flow from turbo-machinery via seal becomes one of the important issues since not only it influences the cycle efficiency due to parasitic loss but also it is important for evaluating the system safety under various operating conditions. In this paper, the gap effect, which is studied by changing the diameter of an orifice, cavity length effect, and the number of tooth effect in a simulated labyrinth seal geometry nozzle are presented. Experimental results under various conditions including not only single phase flow but also two phase flow conditions are presented.
- Published
- 2019
30. Translational assessment of a genetic engineering methodology to improve islet function for transplantationResearch in context
- Author
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Pim P. van Krieken, Anna Voznesenskaya, Andrea Dicker, Yan Xiong, Jae Hong Park, Jeong Ik Lee, Erwin Ilegems, and Per-Olof Berggren
- Subjects
endocrine system ,lcsh:R5-920 ,lcsh:R ,lcsh:Medicine ,lcsh:Medicine (General) - Abstract
Background: The functional quality of insulin-secreting islet beta cells is a major factor determining the outcome of clinical transplantations for diabetes. It is therefore of importance to develop methodological strategies aiming at optimizing islet cell function prior to transplantation. In this study we propose a synthetic biology approach to genetically engineer cellular signalling pathways in islet cells. Methods: We established a novel procedure to modify islet beta cell function by combining adenovirus-mediated transduction with reaggregation of islet cells into pseudoislets. As a proof-of-concept for the genetic engineering of islets prior to transplantation, this methodology was applied to increase the expression of the V1b receptor specifically in insulin-secreting beta cells. The functional outcomes were assessed in vitro and in vivo following transplantation into the anterior chamber of the eye. Findings: Pseudoislets produced from mouse dissociated islet cells displayed basic functions similar to intact native islets in terms of glucose induced intracellular signalling and insulin release, and after transplantation were properly vascularized and contributed to blood glucose homeostasis. The synthetic amplification of the V1b receptor signalling in beta cells successfully modulated pseudoislet function in vitro. Finally, in vivo responses of these pseudoislet grafts to vasopressin allowed evaluation of the potential benefits of this approach in regenerative medicine. Interpretation: These results are promising first steps towards the generation of high-quality islets and suggest synthetic biology as an important tool in future clinical islet transplantations. Moreover, the presented methodology might serve as a useful research strategy to dissect cellular signalling mechanisms of relevance for optimal islet function. Keywords: Diabetes, In vivo imaging, Synthetic biology, Vasopressin, Pseudoislet, Transplantation
- Published
- 2019
31. 12‐3: A Highly Mass‐producible Nano‐lens Array Technology for Optically Efficient Full‐color Organic Light Emitting Diode Display Applications
- Author
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Byoung-Gon Yu, Jang-Joo Kim, Jonghee Lee, Doo-Hee Cho, Hyunkoo Lee, Yoonjay Han, Jeong-Ik Lee, Young Sam Park, Nam Sung Cho, and Kyung-Hoon Han
- Subjects
Materials science ,business.industry ,Nano ,OLED ,Optoelectronics ,Full color ,business ,Lens array - Published
- 2019
32. Implication of LOCA characteristics of large PWR and SMR for future development of intelligent nuclear power plant control system
- Author
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Min-Gil Kim and Jeong-Ik Lee
- Subjects
business.industry ,Computer science ,020209 energy ,media_common.quotation_subject ,Pressurized water reactor ,Human error ,02 engineering and technology ,Modular design ,Root cause ,01 natural sciences ,010305 fluids & plasmas ,law.invention ,Reliability engineering ,Nuclear Energy and Engineering ,law ,Control system ,0103 physical sciences ,Nuclear power plant ,0202 electrical engineering, electronic engineering, information engineering ,Systems design ,business ,Function (engineering) ,media_common - Abstract
Operation with reduced number of operators is considered as an important operational mode to improve economics of a nuclear power plant (NPP) in the future and it will be more important for the small modular reactors (SMRs). To control NPPs efficiently and safely with a reduced number of operators, an intelligent operation system can be very useful. However, reduced number of operators will result in larger consequence in human error due to simultaneous multi-unit failures are now more probable than the conventional operational mode. Thus, to decrease the probability of human error occurrence for the reduced number of operators, the development of an autonomous operation system with certain level of intelligence is inevitable. The prediction capability of system’s behavior as well as understanding the root cause for the current situation should be an essential function of the designed autonomous operation system. The authors propose to use the current system thermal–hydraulic (STH) analysis code platform to develop such intelligence. As a demonstration of the suggested method, the authors used the STH code to track the accident initiator of both large pressurized water reactor (PWR) and SMR. The discussions on how this method can be useful for future NPP operation and how generic differences in system design actually influence the system behavior are presented.
- Published
- 2019
33. Condensation heat transfer and multi-phase pressure drop of CO2 near the critical point in a printed circuit heat exchanger
- Author
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Seong Jun Bae, In-woo Son, Seong Gu Kim, Jeong-Ik Lee, and Jinsu Kwon
- Subjects
Fluid Flow and Transfer Processes ,Pressure drop ,Materials science ,Condensation heat transfer ,020209 energy ,Mechanical Engineering ,02 engineering and technology ,Mechanics ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Supercritical fluid ,Printed circuit board ,Critical point (thermodynamics) ,Heat transfer ,Heat exchanger ,0202 electrical engineering, electronic engineering, information engineering ,0210 nano-technology ,Test data - Abstract
In this study, condensation heat transfer and multi-phase pressure drop of CO2 near the critical point are investigated occurring in a Printed Circuit Heat Exchanger (PCHE) for a supercritical CO2 power cycle application in mind. Homogeneous Equilibrium Model (HEM) approach is used to evaluate and develop appropriate heat transfer and pressure drop correlations. The experiment was performed with the CO2 test facility called SCO2PE (Supercritical CO2 Pressurizing Experiment) in KAIST. The heat transfer and pressure drop test was conducted with the PCHE in the facility. Existing correlations were compared to the test data and a new set of correlations was necessary to be developed. A new set of correlations is newly suggested in this paper which captures physical characteristics reasonably well.
- Published
- 2019
34. Coculture With Ischemia/Reperfusion-Preconditioned Hepatocytes Improves Islet Function and Survival
- Author
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Beom Seok Kim, Jae Geun Lee, Dong Jin Joo, J.Y. Kim, Yu Seun Kim, Jeong Ik Lee, Myoung Soo Kim, Kyu Ha Huh, and Yuri Cho
- Subjects
0301 basic medicine ,endocrine system ,endocrine system diseases ,Cell Survival ,medicine.medical_treatment ,Islets of Langerhans Transplantation ,Andrology ,Neovascularization ,Islets of Langerhans ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Animals ,Insulin ,Insulin-Like Growth Factor I ,Ischemic Preconditioning ,Transplantation ,geography ,geography.geographical_feature_category ,Hepatocyte Growth Factor ,Chemistry ,Growth factor ,Islet ,Coculture Techniques ,030104 developmental biology ,medicine.anatomical_structure ,Terminal deoxynucleotidyl transferase ,030220 oncology & carcinogenesis ,Hepatocyte ,Hepatocytes ,Surgery ,Hepatocyte growth factor ,medicine.symptom ,medicine.drug ,Transforming growth factor - Abstract
In clinical islet transplantation, hepatic ischemia and insufficient neovascularization of transplanted islets are barriers to islet survival and function. However, hepatocytes have a potency to protect themselves against ischemia. We hypothesized that ischemia/reperfusion preconditioning (IRP) of hepatocytes might beneficially affect islet cells in a coculture system. Primary islets were cocultured with primary hepatocytes, and hepatocyte IRP was conducted by subjecting cells to hypoxic conditions for single 15-minute/30-minute hypoxia, or 2 tandem 15-minute/30-minute hypoxic treatments (hypoxic-normoxic-hypoxic). We show that gene expression levels of insulin-like growth factor 1 (IGF-1), hepatocyte growth factor (HGF), transforming growth factor-α (TGF-α), and TGF-β1 in hepatocytes were increased by IRP. IRP hepatocytes secreted hepatocyte growth factor and insulin-like growth factor-1. Coculture of islets with IRP hepatocytes enhanced islet insulin secretion in glucose challenge test and expression of the survival-related gene Bcl-2 and the regenerating gene-1α (Reg-1α). Islets cocultured with the 30-minute double-IRP hepatocytes displayed significantly higher viability in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and terminal deoxynucleotidyl transferase dUTP nick end labeling stain compared with that of islets subjected to 30 minutes of hypoxia. These results suggest that islet coculture with IRP hepatocytes can improve islet survival and insulin secretion.
- Published
- 2018
35. Device Characteristics of Top-Emitting Organic Light-Emitting Diodes Depending on Anode Materials for CMOS-Based OLED Microdisplays
- Author
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Nam Sung Cho, Hokwon Kim, Jun-Han Han, Minseok Kim, Chun-Won Byun, Jeong Hwan Lee, Hyunsu Cho, Hyunkoo Lee, Jeong-Ik Lee, and Chan-mo Kang
- Subjects
Organic light-emitting diodes (OLEDs) ,lcsh:Applied optics. Photonics ,Materials science ,chemistry.chemical_element ,02 engineering and technology ,Tungsten ,01 natural sciences ,chemistry.chemical_compound ,0103 physical sciences ,OLED ,lcsh:QC350-467 ,Electrical and Electronic Engineering ,Sheet resistance ,Diode ,010302 applied physics ,business.industry ,CMOS ,lcsh:TA1501-1820 ,021001 nanoscience & nanotechnology ,microdisplay ,Titanium nitride ,Atomic and Molecular Physics, and Optics ,Anode ,chemistry ,Optoelectronics ,OLEDoS ,0210 nano-technology ,Tin ,business ,lcsh:Optics. Light - Abstract
We investigated the optical reflectance, surface roughness, and sheet resistance of aluminum (Al)/titanium nitride (TiN), titanium (Ti), and tungsten (W) layers on Si substrates, which are available in the CMOS foundry, for organic light-emitting diode (OLED) microdisplays. The devices with different metal anode layers exhibited different hole-injection properties and OLED performances, owing to the different optical and electrical properties of metal anode layers. Based on the OLED characteristics, the Al/TiN layer was selected as an anode layer for OLED microdisplays. A green monochromatic OLED microdisplay panel was designed and implemented using the 0.11-μm CMOS process. The density of pixels was ~2 351 pixels per inch and the panel's active area was 0.7 in in diagonal. The resolution of the panel was 1 280 × 3 × 1 024, corresponding to SXGA. The panel was successfully operated, and the maximal luminance was ~460 cd/m2.
- Published
- 2018
36. Using Resveratrol and Epigallocatechin-3-Gallate to Improve Cryopreservation of Stallion Spermatozoa With Low Quality
- Author
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Jeong Ik Lee, Kamal Shojaeian, Houshang Nouri, F. Samadian, Hamid Kohram, and Soojung Lee
- Subjects
030219 obstetrics & reproductive medicine ,Equine ,Extender ,0402 animal and dairy science ,food and beverages ,Semen ,04 agricultural and veterinary sciences ,Biology ,040201 dairy & animal science ,Sperm ,Cryopreservation ,law.invention ,Andrology ,Lipid peroxidation ,03 medical and health sciences ,Semen quality ,chemistry.chemical_compound ,0302 clinical medicine ,chemistry ,law ,Acrosome ,Spermatogenesis - Abstract
Reactive oxygen species levels in semen with low quality increased from 25% to about 40%. Resveratrol (Res) is a natural grape-derived phytoalexin, and epigallocatechin-3-gallate (EGCG) is the major polyphenol in green tea (Camellia sinensis); both molecules are known to have high levels of antioxidant activity. The aim of this study was to investigate the effects of this antioxidant's supplementation on cryopreservation of stallion semen with poor quality. Experiment 1: Experiment design to asses stallions semen quality (n = 3). Arabian stallions were managed for breeding with fresh, extended, or chilled semen during 2 years (in two breeding season) with a resulting per cycle pregnancy rate (103/41 estrus cycle/conception) of 39.80%. A total of 81 ejaculates were collected and evaluated in fresh condition (total and progressive motility, membrane integrity, acrosome defects, morphology, and abnormal DNA condensation). Evaluation of several ejaculates revealed that sperm production and semen quality mostly did not change during the breeding season, maintaining normal sperm production with poor quality. Experiment 2: 18 ejaculates, collected with Missouri model artificial vagina from Arabian stallion (n = 3). Extended semen was centrifuged at 600 × g for 10 minutes. To eliminate individual stallion variability, the resulting sperm pellets were pooled and divided in seven different treatments in a final concentration of 100 × 106 sperm/mL by using semiskimmed milk extender containing no supplements (control), and the following supplements with three different concentrations: Res 5, 10, and 20 μM (Res 1, Res 2, Res 3, respectively) and EGCG 25, 50, 100 μM (EGCG 1, EGCG 2, and EGCG 3, respectively). After thawing, all samples were maintained at 37°C for 10 minutes. Evaluation of motility, plasma membrane integrity, viability, mitochondria activity, DNA fragmentation, and lipid peroxidation was determined. For all semen parameters, the lower concentration of Res (5 μM) and EGCG (25 μM) did not show significant differences compared to control (P > .05). Relative to the control group, Res 2 had better (P
- Published
- 2018
37. Luminescence enhancement of OLED lighting panels using a microlens array film
- Author
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Nam Sung Cho, Doo-Hee Cho, Hye Yong Chu, Jaehyun Moon, Jeong-Ik Lee, Jun-Han Han, Jin-Wook Shin, and Jonghee Lee
- Subjects
010302 applied physics ,Microlens ,lcsh:Computer engineering. Computer hardware ,Materials science ,lighting ,business.industry ,lcsh:TK7885-7895 ,02 engineering and technology ,light extraction ,021001 nanoscience & nanotechnology ,01 natural sciences ,Luminance ,OLED ,0103 physical sciences ,microlens array (MLA) film ,Optoelectronics ,General Materials Science ,Electrical and Electronic Engineering ,0210 nano-technology ,Luminescence ,business ,Diode - Abstract
The enhancement of the luminance of organic light-emitting diode (OLED) panels with various areas (2.25–6084 mm2) using a microlens array (MLA) film was investigated. The luminance enhancement was dependent on the viewing angle, and the largest enhancement (64%) was observed in the normal direction while 60 and 18% enhancements were observed at 60 and 30°, which led to lower enhancement (38%) of the total luminous flux compared with the luminance enhancement (64%) in the normal direction. The luminance enhancement with the MLA film also depended on the panel area, and the smaller panels showed lower luminance enhancement than the larger ones. As for the small panels, the straying light beyond the panel areas significantly affected the luminance of the panels, and over 60% luminance enhancement was observed in the normal direction for the large panels (2500 and 6084 mm2) with the MLA film while only 48 and 58% luminance enhancements were observed at the small panels (2.25 and 70 mm2).
- Published
- 2018
38. The Significance of Extra-Cage Bridging Bone via Radiographic Lumbar Interbody Fusion Criterion
- Author
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Kwang-Sup Song, Dong Hoon Lee, Chan-Woo Jung, and Jeong Ik Lee
- Subjects
Orthodontics ,Bridging (networking) ,medicine.diagnostic_test ,business.industry ,Radiography ,Computed tomography ,Lumbar interbody fusion ,medicine ,Orthopedics and Sports Medicine ,Surgery ,Lumbar spine ,Neurology (clinical) ,Cage ,business - Abstract
Study Design: Prospective observational study. Objectives: We aimed to analysis the distributional patterns of the intra- and extra-cage bridging bone (InCBB and ExCBB) and the significance of ExCBB using suggested lumbar interbody fusion criterion. Methods: This study included the patients with planned single-level transforaminal lumbar interbody fusion. We divided bridging bone into InCBB (in void of right or left cage) and ExCBB (outside of cages; anterior, posterior, intermediate, right, or left) and graded bridging scores from 0 to 2 on postoperative 1-year computed tomography. The fusion was defined as at least having one or more graded 2 and the evaluation were conducted twice by 2 raters. Results: Sixty-five patients were enrolled. All values of intra- and inter-rater reliability in left InCBB, anterior, and posterior ExCBB showed good agreements (≥0.75). Both InCBBs showed similar mean bridging scores (Rt:1.43 vs Lt:1.48), and in ExCBBs, the anterior was the highest (1.43), followed by the posterior (1.14); the right and left were the lowest (0.49 and 0.52 respectively). In subjects determined as fusion (85.4%), complete bridging was observed more in ExCBB (88.8%) than in InCBB (69.9%). Conclusions: Given the higher bridging scores in both InCBBs and Ant. ExCBB, bone grafting is important promoting factor to increase the interbody bridging bone regardless of outside or in void of cages. Based on our suggested criterion, ExCBB has a greater proportion compared to InCBBs for determining the fusion and extra-cage bone grafting should be considered as important procedures for interbody fusion.
- Published
- 2021
39. Solvent-assisted strongly enhanced light-emitting electrochemiluminescent devices for lighting applications
- Author
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Jisu Han, Sooji Nam, Dae Kyom Kim, Joo Yeon Kim, Sang-Hoon Cheon, Chi-Sun Hwang, Yuanzhe Piao, and Jeong-Ik Lee
- Subjects
Solvent system ,chemistry.chemical_classification ,Brightness ,Materials science ,General Chemical Engineering ,Inorganic chemistry ,Salt (chemistry) ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Solvent ,chemistry.chemical_compound ,chemistry ,Propylene carbonate ,Electrochemiluminescence ,0210 nano-technology ,Rubrene ,Tetrahydrofuran - Abstract
Rubrene-based electrochemiluminescence (r-ECL) cells with two different solvent systems is prepared, one in a co-solvent system with a mixture of 1,2-dichlorobenzene and propylene carbonate (DCB : PC, v/v 3 : 1) and another in a single solvent system of tetrahydrofuran (THF), as the medium to form a liquid-electrolyte (L-El). By simply changing the solvent systems, from the co-solvent DCB : PC (v/v 3 : 1) to the single solvent THF, with the same amount of electrochemiluminescent rubrene (5 mM) and Li-based salt, a dramatically enhanced brightness of over 30 cd m−2 is observed for the r-ECL cell in L-ElTHF which is approximately 7-times higher than the brightness of 5 cd m−2 observed for the r-ECL in L-ElDCB:PC(v/v 3:1).
- Published
- 2020
40. Analysis of nodalization uncertainty for nuclear system analysis code with Lax-Wendroff numerical scheme
- Author
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Wonwoong Lee, Jae Jun Lee, and Jeong Ik Lee
- Subjects
Nuclear Energy and Engineering - Published
- 2022
41. Performance Evaluation of Supercritical Carbon Dioxide Recompression Cycle for High Temperature Electric Thermal Energy Storage
- Author
-
Seunghwan Oh, Bong Seong Oh, and Jeong Ik Lee
- Subjects
Fuel Technology ,Nuclear Energy and Engineering ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology - Published
- 2022
42. Thermodynamic analysis of compressed and liquid carbon dioxide energy storage system integrated with steam cycle for flexible operation of thermal power plant
- Author
-
Yong Jae Chae and Jeong Ik Lee
- Subjects
Fuel Technology ,Nuclear Energy and Engineering ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology - Published
- 2022
43. Polythiophene hybrid film with zirconium–porphyrin metal–organic framework for improved charge carrier transport and NO2 gas sensing
- Author
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Jeong Ik Lee, Miyeon Kim, Kyoung Chul Park, Chang Yeon Lee, and Yeong Don Park
- Subjects
General Materials Science ,Condensed Matter Physics - Published
- 2022
44. Experimental investigation of tank stratification in liquid air energy storage (LAES) system
- Author
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Jung Hwan Park, Jeong-Ik Lee, and Jin Young Heo
- Subjects
Electricity generation ,Nuclear engineering ,Storage tank ,Liquid air ,Energy Engineering and Power Technology ,Destratification ,Environmental science ,Stratification (water) ,Cryogenic energy storage ,Vacuum level ,Liquid nitrogen ,Industrial and Manufacturing Engineering - Abstract
Liquid air energy storage technology is a technology that stores liquid air in case of excess power supply and evaporates the stored liquid air to start a power generation cycle when there is an electric power demand. When liquid air is stored for a long-time during operation, safety and performance degradation can be caused or mitigated by the tank stratification. To investigate the tank stratification phenomenon and associated issues, an experimental facility is constructed. The heat ingress is controlled with respect to changing vacuum level in the experiment. Furthermore, the conditions under which stratification occurs are defined in terms of temperature and concentration, and based on this, the stratification stability ratio and the stability map are defined and evaluated experimentally. The results show that the time required for destratification is 8-29% shorter for liquid air mixture cases than for liquid nitrogen. Moreover, the time required for destratification is 2.4 times longer for the high tank pressure cases, and it is 39% shorter for the case of high heat ingress. From experimental observations, an operation strategy utilizing stratification inside the liquid air storage tank is newly suggested that can minimize the boil-off gas of liquid air in the tank.
- Published
- 2022
45. Techno-economic study of nuclear integrated liquid air energy storage system
- Author
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Jin Young Heo, Jeong-Ik Lee, and Jung Hwan Park
- Subjects
Rankine cycle ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy Engineering and Power Technology ,Cryogenic energy storage ,Energy storage ,law.invention ,Renewable energy ,Fuel Technology ,Nuclear Energy and Engineering ,Steam turbine ,law ,Nuclear power plant ,Environmental science ,Air compressor ,Cost of electricity by source ,Process engineering ,business - Abstract
The significant increase of renewable energy source is expected to induce stability issue of electric grid due to the intermittency of renewable energy. The challenge of intermittency is making energy storage system more important. Among the grid-scale energy storage systems, a Liquid Air Energy Storage System is increasingly popular with its high energy density, long expected service lifetime, less operation and maintenance cost, and less geographical constraint. At the same time, flexibility of nuclear power plant is becoming more important with higher penetration of renewable energy sources. However, load-following operation not only causes safety issues on the fuel integrity, but also leads to economic deterioration of nuclear power plant. In this study, the new concept is suggested by mechanically integrating nuclear steam cycle and liquid air energy storage system to achieve high flexibility and economy of a nuclear power plant. At off peak hour, nuclear energy is stored by bypassing steam from nuclear steam cycle to external steam turbine which mechanically connected to air compressor in the liquid air energy storage system. Air is compressed by air compressor and liquefied by cold energy storage system. At peak hours, the stored energy is recovered by evaporating and expanding. The thermodynamic and economic analyses are conducted on standalone liquid air energy storage system and nuclear integrated liquid air energy storage system to further examine the benefits of the proposed system. The results show that the round-trip efficiency of the proposed system is around 51% and the energy density is 116 kWh/m3. The round-trip efficiency is competitive and the energy density is superior to other grid-scale energy storage system. Also, the integration improves the capacity factor of nuclear power plant by 3%p. The Levelized Cost of Electricity shows $219.8/MWh for standalone liquid air energy storage system and $182.6/MWh for nuclear integrated liquid air energy storage system, reducing 17% of the standalone systems’ cost. The results show that the proposed concept can achieve better economy than using standalone liquid air energy storage system as well as other energy storage systems. In conclusion, the proposed nuclear integrated liquid air energy storage system has very good potential to become a competitive energy storage option and can assist to stabilize the future electricity grid with high reliance on renewable energy.
- Published
- 2022
46. Techno-economic evaluation of solar-nuclear hybrid system for isolated grid
- Author
-
In Woo Son, Jeong-Ik Lee, Yongju Jeong, Seongmin Son, and Jung Hwan Park
- Subjects
business.industry ,Mechanical Engineering ,Building and Construction ,Management, Monitoring, Policy and Law ,Nuclear power ,Thermal energy storage ,Energy storage ,General Energy ,Hybrid system ,Environmental science ,Microgrid ,Cost of electricity by source ,Process engineering ,business ,Energy source ,Solar power - Abstract
A solar-nuclear hybrid system that combines Concentrating Solar Power (CSP) and nuclear power was suggested previously to meet the electricity demands for remote microgrids. The hybrid system combines CSP, Thermal Energy Storage (TES) and a Micro Modular Reactor (MMR). A Supercritical Carbon dioxide (sCO2) power system is used for power generation system. CSP, which has relatively high efficiency, no refueling, low operation and installation costs, is suitable as an energy source for the microgrid. However, since it is challenging to meet 100% electricity demand with a standalone CSP system due to excessive energy storage system and large land area requirement, a hybrid system is proposed by adding a nuclear system to resolve this issue. The hybrid system showed a higher capacity factor than the standalone CSP system while reducing the required energy storage. However, the TES capacity was still excessive to meet 100% of the electricity demand in the previous study to overcome seasonal variation. Therefore, in this study, the hybrid system is re-designed by optimizing solar to nuclear ratio while tracing change in the Levelized Cost Of Electricity (LCOE) of the system. A sensitivity analysis is performed with respect to the five variables; nuclear to solar heat ratio, direct normal irradiation, peak-to-average electricity demand ratio, nuclear island cost, discount rate affecting LCOE. As a result of economic evaluation, it is confirmed that the hybrid system is cost competitive to the standalone CSP system. This study showed that the nuclear-CSP hybrid system can be utilized as a power source with a high potential for isolated microgrid.
- Published
- 2022
47. Preliminary design of safety system using phase change material for passively cooling of nuclear reactor containment building
- Author
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Sung Gil Shin, A-Reum Ko, Hwa-Young Jung, Jai Oan Cho, and Jeong-Ik Lee
- Subjects
business.industry ,Nuclear engineering ,Containment building ,Energy Engineering and Power Technology ,Heat sink ,Nuclear reactor ,Phase-change material ,Industrial and Manufacturing Engineering ,law.invention ,law ,Heat transfer ,Water cooling ,Environmental science ,business ,Condenser (heat transfer) ,Thermal energy - Abstract
The new application of phase change material for passively cooling the containment building of a nuclear power plant provides many benefits such as minimized wall penetration, low maintenance cost, and the possibility of installation in currently operating power plants with a minimal design change. In this study, the applicability of PCM as a passive containment cooling system is verified through design and evaluation of the PCM condenser. In addition, the effective heat capacity method is verified for simulating the melting process of PCM in the condition of a reactor accident. The PCM condenser design is optimized with five design parameters; melting point, volume, heat transfer area, effective thermal conductivity, and total heat absorbed. The performance of the PCM condenser is evaluated by containment safety analysis and is compared to that of an active containment cooling system. Although the PCM condenser had a limitation for absorbing only a fixed amount of thermal energy due to the absence of an external heat sink, the PCM condenser shows better performance in the early stage after the accident initiation compared to the single spray system and finally maintains the integrity of the containment building.
- Published
- 2022
48. Impact of Turbomachinery Degradation on Performance and Dynamic Behavior of Supercritical CO2 Cycle
- Author
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Yongju Jeong, Jeong Yeol Baek, Seongmin Son, and Jeong-Ik Lee
- Subjects
business.industry ,020209 energy ,Mechanical Engineering ,Energy Engineering and Power Technology ,Aerospace Engineering ,02 engineering and technology ,Supercritical fluid ,Fuel Technology ,Nuclear Energy and Engineering ,Turbomachinery ,0202 electrical engineering, electronic engineering, information engineering ,Degradation (geology) ,Environmental science ,Process engineering ,business ,Gas compressor - Abstract
Due to small footprint and high efficiency, a Supercritical CO2 (S-CO2) power cycle is considered to be one of the promising next-generation power cycles. Although S-CO2 is reported as a powerful cleaning agent, the performance of a power system operating with S-CO2 will also inevitably degrade over time. Previous researchers have shown that turbomachinery deterioration could be a major subject regarding the system performance degradation. Nevertheless, no quantitative evaluation has yet been made so far. In this study, the impact of the performance degradation of the S-CO2 turbomachinery on the overall performance of the system is analyzed quantitatively. The concept of Health Parameter is used to simulate turbomachinery degradation. To quantify the impact, an S-CO2 direct-cycle small modular reactor is selected as a target system. A transient analysis platform is built using a nuclear system safety analysis code and the deep neural network (DNN)-based S-CO2 turbomachinery off-design performance model. System dynamics are evaluated for primary frequency control ability and secondary load-following capability. Results show that the control problems during the transient state can occur when the output fluctuations are large and the performance degradation is severe. It has been confirmed that even control failures of the PID controllers can occur. Therefore, the performance degradation of turbomachinery must be monitored and considered, for an operation strategy for S-CO2 systems.
- Published
- 2020
49. Ginseng Gintonin Contains Ligands for GPR40 and GPR55
- Author
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Hongik Hwang, Seung-Yeol Nah, Hyoung-Chun Kim, Jeong Ik Lee, Hyewhon Rhim, Rami Lee, Sun-Hye Choi, Ik-Hyun Cho, Yeon-Jin Cho, and Sung-Hee Hwang
- Subjects
insulin secretion ,cell migration ,medicine.drug_class ,Pharmaceutical Science ,Panax ,ginseng ,Ligands ,Article ,Analytical Chemistry ,Receptors, G-Protein-Coupled ,lcsh:QD241-441 ,03 medical and health sciences ,Ginseng ,chemistry.chemical_compound ,0302 clinical medicine ,lcsh:Organic chemistry ,Cell Movement ,Free fatty acid receptor 1 ,Drug Discovery ,Lysophosphatidic acid ,medicine ,Animals ,Humans ,Calcium Signaling ,Physical and Theoretical Chemistry ,Receptor ,Receptors, Cannabinoid ,030304 developmental biology ,G protein-coupled receptor ,GPR40 ,0303 health sciences ,Dose-Response Relationship, Drug ,Chemistry ,Plant Extracts ,Organic Chemistry ,Receptor antagonist ,Cell biology ,Rats ,gintonin ,GPR55 ,Chemistry (miscellaneous) ,PC-3 Cells ,Lysophosphatidylinositol ,Molecular Medicine ,030217 neurology & neurosurgery - Abstract
Gintonin, a novel ginseng-derived glycolipoprotein complex, has an exogenous ligand for lysophosphatidic acid (LPA) receptors. However, recent lipid analysis of gintonin has shown that gintonin also contains other bioactive lipids besides LPAs, including linoleic acid and lysophosphatidylinositol (LPI). Linoleic acid, a free fatty acid, and LPI are known as ligands for the G-protein coupled receptors (GPCR), GPR40, and GPR55, respectively. We, herein, investigated whether gintonin could serve as a ligand for GPR40 and GPR55, using the insulin-secreting beta cell-derived cell line INS-1 and the human prostate cancer cell line PC-3, respectively. Gintonin dose-dependently enhanced insulin secretion from INS-1 cells. Gintonin-stimulated insulin secretion was partially inhibited by a GPR40 receptor antagonist but not an LPA1/3 receptor antagonist and was down-regulated by small interfering RNA (siRNA) against GPR40. Gintonin dose-dependently induced [Ca2+]i transients and Ca2+-dependent cell migration in PC-3 cells. Gintonin actions in PC-3 cells were attenuated by pretreatment with a GPR55 antagonist and an LPA1/3 receptor antagonist or by down-regulating GPR55 with siRNA. Taken together, these results demonstrated that gintonin-mediated insulin secretion by INS-1 cells and PC-3 cell migration were regulated by the respective activation of GPR40 and GPR55 receptors. These findings indicated that gintonin could function as a ligand for both receptors. Finally, we demonstrated that gintonin contained two more GPCR ligands, in addition to that for LPA receptors. Gintonin, with its multiple GPCR ligands, might provide the molecular basis for the multiple pharmacological actions of ginseng.
- Published
- 2020
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50. Ultraflexible and transparent electroluminescent skin for real-time and super-resolution imaging of pressure distribution
- Author
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Seung-Youl Kang, Yongtaek Hong, Jiseok Seo, Hanul Kim, Ji-Young Oh, Hyungsoo Yoon, Seunghwan Lee, Chan Woo Park, Seongdeok Ahn, Sujin Jeong, Chul Woong Joo, Nae-Man Park, Chi-Sun Hwang, Sukyung Choi, Junghwan Byun, Byeongmoon Lee, Jeong-Ik Lee, Hyeon Cho, and Eunho Oh
- Subjects
Materials science ,Science ,Biomedical Engineering ,Nanowire ,Electronic skin ,General Physics and Astronomy ,Biosensing Techniques ,02 engineering and technology ,Electroluminescence ,010402 general chemistry ,01 natural sciences ,Article ,General Biochemistry, Genetics and Molecular Biology ,Wearable Electronic Devices ,Imaging, Three-Dimensional ,Pressure ,Humans ,lcsh:Science ,Skin ,Multidisciplinary ,integumentary system ,Pixel ,Nanowires ,business.industry ,Electric Conductivity ,Response time ,Robotics ,General Chemistry ,021001 nanoscience & nanotechnology ,Superresolution ,Electrical and electronic engineering ,Sensors and biosensors ,0104 chemical sciences ,Optoelectronics ,lcsh:Q ,Artificial intelligence ,0210 nano-technology ,business ,Pixel density - Abstract
The ability to image pressure distribution over complex three-dimensional surfaces would significantly augment the potential applications of electronic skin. However, existing methods show poor spatial and temporal fidelity due to their limited pixel density, low sensitivity, or low conformability. Here, we report an ultraflexible and transparent electroluminescent skin that autonomously displays super-resolution images of pressure distribution in real time. The device comprises a transparent pressure-sensing film with a solution-processable cellulose/nanowire nanohybrid network featuring ultrahigh sensor sensitivity (>5000 kPa−1) and a fast response time (1000 dpi) pressure imaging without the need for pixel structures. Our approach provides a new framework for visualizing accurate stimulus distribution with potential applications in skin prosthesis, robotics, and advanced human-machine interfaces., Electronic skin that spatially maps pressure distribution through imaging shows limited performance despite improvements to data acquisition. Here, the authors report ultraflexible, transparent electroluminescent skin capable of high-resolution imaging of pressure distribution over 3D surfaces.
- Published
- 2020
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