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744 results on '"Kim, Jeong-Won"'

158. Effects of intermolecular interaction on the energy distribution of valance electronic states of a carbazole-based material in amorphous thin films.

Author

Kwon, Soonnam, Wee, Kyung-Ryang, Kim, Jeong Won, Pac, Chyongjin, and Kang, Sang Ook

Subjects
INTERMOLECULAR interactions, SPECTRAL energy distribution, ELECTRONICS, AMORPHOUS substances, CARBAZOLE, THIN films, ELECTRONIC structure
Abstract

Effects of intermolecular interactions on the occupied electronic structure of amorphous solid of a carbazole-based material were investigated under an assumption that the organic solid consists of randomly oriented assemblies of dimers. The electronic energy states were calculated on the ensemble of large number of random dimers, of which geometries are relaxed using semiempirical van der Waals density functional theory. Intermolecular interactions result in splitting of energy level, and further disorders occur by aggregation of randomly orientated molecules. As a result, frontier occupied energy states can be represented by a superposition of Gaussian distributions, including (i) a main distribution with full width at half maximum of 80-110 meV, depending on the methods of relaxation and (ii) shoulders separated from the center of the main distribution with a value as large as 150 meV. A possible origin for the appearance of these shoulders was ascribed to the presence of molecular assemblies consisting of more tightly bound dimers compared with the others. [ABSTRACT FROM AUTHOR]

Published
2012
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159. Tunable work function of a WOx buffer layer for enhanced photocarrier collection of pin-type amorphous silicon solar cells.

Author

Fang, Liang, Baik, Seung Jae, Kim, Jeong Won, Kang, Sang Jung, Seo, Jung Won, Jeon, Jin-Wan, Kim, Yoon Hak, and Lim, Koeng Su

Subjects
TUNGSTEN oxides, SILICON research, SOLAR cells, ULTRAVIOLET radiation, BUFFER solutions
Abstract

An in situ postdeposition ultraviolet treatment was proposed to improve the electrical properties of a tungsten oxide (WOx) buffer layer of pin-type amorphous silicon-based solar cell. Based on the x-ray and ultraviolet photoelectron spectroscopy and the activation energy measurements, it was found that the work function of WOx is tunable by ultraviolet light treatment, and the collection performance of solar cells incorporating WOx with the lower work function is further improved. Moreover, the optimal band alignment scheme for a window layer is discussed in terms of obtaining enhanced carrier collection without open circuit voltage degradation. [ABSTRACT FROM AUTHOR]

Published
2011
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160. VAMAS Inter-Laboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings using XPS and LEIS

Author

Belsey, Natalie, Cant, David, Minelli, Caterina, Araujo, Joyce, Bock, Bernd, Brüner, Philipp, Castner, David, Ceccone, Giacomo, Counsell, Jonathan, Dietrich, Paul, Engelhard, Mark, Fearn, Sarah, Galhardo, Carlos, Kalbe, Henryk, Kim, Jeong Won, Lartundo-Rojas, Luis, Luftman, Henry, Nunney, Tim, Pseiner, Johannes, Smith, Emily, Spampinato, Valentina, Sturm, Jacobus, Thomas, Andrew, Treacy, Jon, Veith, Lothar, Wagstaffe, Michael, Wang, Hai, Wang, Mailing, Wang, Yung-Chen, Werner, Wolfgang, Yang, Li, and Shard, Alex

Abstract

We report the results of a Versailles Project on Advanced Materials and Standards (VAMAS) interlaboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS. Degradation during transportation, storage, or sample preparation resulted in a variability in thickness of 53%. The calculation method chosen by XPS participants contributed a variability of 67%. However, variability of 12% was achieved for the samples deposited using a single method and by choosing photoelectron peaks that were not adversely affected by instrumental transmission effects. The study identified a need for more consistency in instrumental transmission functions and relative sensitivity factors since this contributed a variability of 33%. The results from the LEIS participants were more consistent, with variability of less than 10% in thickness, and this is mostly due to a common method of data analysis. The calculation was performed using a model developed for uniform, flat films, and some participants employed a correction factor to account for the sample geometry, which appears warranted based upon a simulation of LEIS data from one of the participants and comparison to the XPS results.

Published
2016
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165. Anomalous Ambipolar Transport of Organic Semiconducting Crystals via Control of Molecular Packing Structures

Author

Park, Beomjin, primary, Kim, Kyunghun, additional, Park, Jaesung, additional, Lim, Heeseon, additional, Lanh, Phung Thi, additional, Jang, A-Rang, additional, Hyun, Chohee, additional, Myung, Chang Woo, additional, Park, Seungkyoo, additional, Kim, Jeong Won, additional, Kim, Kwang S., additional, Shin, Hyeon Suk, additional, Lee, Geunsik, additional, Kim, Se Hyun, additional, Park, Chan Eon, additional, and Kim, Jin Kon, additional

Published
2017
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177. Multipath Mitigation Method Through Asymmetry Estimation of Correlation Function

Author

Lee Sang-Jeong, Moon Sung-Wook, Jang Han-Jin, Kim Jeong-Won, and Hwang Dong-Hwan

Subjects
Multipath mitigation, business.industry, media_common.quotation_subject, Correlation function (quantum field theory), Chip, Signal, Asymmetry, Correlation, Electronic engineering, Global Positioning System, business, Algorithm, Multipath propagation, Mathematics, media_common
Abstract

Since the muiltipath signal arrives at the GPS receiver later than the line-of-sight signal, the multipath signal makes the shape of the correlation function asymmetric. This paper proposes a multipath mitigation method through asymmetry estimation of the correlation function, in which multiple correlators are utilized. The asymmetry is estimated from correlation values of correlators which have different chip spacings. Based on the estimated asymmetry, the correlation function is modified in order to get a better code tracking performance. Even through the proposed method uses multiple correlators including the narrow correlator, the acquisition performance is not degraded since the number of search cell of the narrow correlator part can be reduced in the algorithm of the proposed method. The simulation results show that the proposed method gives better performance than the generic correlator in multipath environment.

Published
2006
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178. Performance Improvement of INS Velocity-aided GPS Carrier Tracking Loop

Author

Hwang Dong-Hwan, Lee Sang-Jeong, and Kim Jeong-Won

Subjects
Tracking error, Phase-locked loop, Engineering, Control theory, business.industry, Bandwidth (signal processing), GPS/INS, Tracking loop, Global Positioning System, Feedback loop, Performance improvement, business
Abstract

This paper presents performance improvement of the INS velocity-adided GPS carier tracking loop. To this end, INS velocity-aided GPS carrier tracking loop was modeled as a feedfoward and a feedback loop system. In the phase tracking loop, it was shown that the tracking error caused by the dynamic motion of the vehicle can be compensated with the aiding of the INS information irrespective of the loop order and bandwidth. However, the signal trcking error increases as the INS error increases. It was also shown that in order to remove the tracking error caused by INS bias error, more than or equal to 2nd order PLL should be used. Experiments were carried out and the experimental results were compared with the analysis results.

Published
2006
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179. Design of Internet Based DGPS Mobile Reference Station

Author

Hwang Dong-Hwan and Kim Jeong Won

Subjects
Precision Lightweight GPS Receiver, Engineering, Defense Advanced GPS Receiver, Internet based, business.industry, Mobile station, Assisted GPS, Real-time computing, The Internet, business, Differential GPS, Networking hardware
Abstract

This paper proposes a DGPS (Differential GPS) mobile reference station. The proposed systems can provide user with real-time correction data when the internet connention is possible. Since the GPS receiver part and network hardware are designed in a module, it can be easily moved and fixed. In order to verify the proposed system, several tersts have been carried out and the test results show the validity of the proposed system.

Published
2006
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180. Anomalous Ambipolar Transport of Organic Semiconducting Crystals via Control of Molecular Packing Structures

Author

Park, Beomjin, Kim, Kyunghun, Park, Jaesung, Lim, Heeseon, Lanh, Phung Thi, Jang, A-Rang, Hyun, Chohee, Myung, Chang Woo, Park, Seungkyoo, Kim, Jeong Won, Kim, Kwang S., Shin, Hyeon Suk, Lee, Geunsik, Kim, Se Hyun, Park, Chan Eon, and Kim, Jin Kon

Abstract

Organic crystals deposited on 2-dimensional (2D) van der Waals substrates have been widely investigated due to their unprecedented crystal structures and electrical properties. van der Waals interaction between organic molecules and the substrate induces epitaxial growth of high quality organic crystals and their anomalous crystal morphologies. Here, we report on unique ambipolar charge transport of a “lying-down” pentacene crystal grown on a 2D hexagonal boron nitride van der Waals substrate. From in-depth analysis on crystal growth behavior and ultraviolet photoemission spectroscopy measurement, it is revealed that the pentacene crystal at the initial growth stage have a lattice-strained packing structure and unique energy band structure with a deep highest occupied molecular orbital level compared to conventional “standing-up” crystals. The lattice-strained pentacene few layers enable ambipolar charge transport in field-effect transistors with balanced hole and electron field-effect mobilities. Complementary logic circuits composed of the two identical transistors show clear inverting functionality with a high gain up to 15. The interesting crystal morphology of organic crystals on van der Waals substrates is expected to attract broad attentions on organic/2D interfaces for their electronic applications.

Published
2024
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181. Quality Assessment of Proteins and RNA Following Storage in Archival Formalin-Fixed Paraffin-Embedded Human Breast Cancer Tissue Microarray Sections

Author

Kim, Kyungeun, Ylaya, Kris, Perry, Candice, Lee, Mi-Yeon, Kim, Jeong Won, Chung, Joon-Yong, and Hewitt, Stephen M.

Abstract

Although the immunogenicity of formalin-fixed paraffin-embedded tissue sections can decrease during storage and transport, the exact mechanism of antigenic loss and how to prevent it are not clear. Herein, we investigated changes in the expression of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2), E-cadherin, and Ki-67 in human breast tissue microarray (TMA) tissue sections stored for up to 3 months in dry and wet conditions. The positive rates of ER and PR expression were minimally changed after 3 months of storage, but the Allred scores of ER and PR stored in humid conditions decreased remarkably in comparison to fresh-cut tissue. The HER-2 antigenicity and RNA integrity of breast TMA sections stored in dry conditions diminished gradually with storage time, whereas the immunoreactivity and RNA quality of HER-2 in humid conditions decreased sharply as storage length increased. The area and intensity of E-cadherin staining in tissue sections stored in dry conditions did not change significantly and were minimally changed after 3 months, respectively. In contrast, the area and intensity of E-cadherin staining in tissue sections stored in humid conditions decreased significantly as storage length increased. Finally, the Ki-67 labeling index of tissue sections stored for 3 months in dry (9% decrease) and wet (31.9% decrease) conditions was decreased in comparison to fresh sections. In conclusion, these results indicate that water is a crucial factor for protein and RNA degradation in stored tissue sections, and detailed guidelines are required in the clinic.

Published
2024
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185. Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS

Author

Belsey, Natalie A., primary, Cant, David J. H., additional, Minelli, Caterina, additional, Araujo, Joyce R., additional, Bock, Bernd, additional, Brüner, Philipp, additional, Castner, David G., additional, Ceccone, Giacomo, additional, Counsell, Jonathan D. P., additional, Dietrich, Paul M., additional, Engelhard, Mark H., additional, Fearn, Sarah, additional, Galhardo, Carlos E., additional, Kalbe, Henryk, additional, Kim, Jeong Won, additional, Lartundo-Rojas, Luis, additional, Luftman, Henry S., additional, Nunney, Tim S., additional, Pseiner, Johannes, additional, Smith, Emily F., additional, Spampinato, Valentina, additional, Sturm, Jacobus M., additional, Thomas, Andrew G., additional, Treacy, Jon P.W., additional, Veith, Lothar, additional, Wagstaffe, Michael, additional, Wang, Hai, additional, Wang, Meiling, additional, Wang, Yung-Chen, additional, Werner, Wolfgang, additional, Yang, Li, additional, and Shard, Alexander G., additional

Published
2016
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198. Role of Na in solution-processed CuInSe2 (CISe) devices: A different story for improving efficiency.

Author

Rehan, Shanza, Moon, Jihyun, Kim, Tae Gun, Gwak, Jihye, Kim, Juran, Kim, Jeong Won, Jo, William, Ahn, Seung Kyu, and Ahn, SeJin

Abstract

Na has been believed to improve the device parameters of open circuit voltage (V OC ) and fill factor (FF) presumably by increasing the carrier concentration (N A ) of vacuum-processed Cu(In,Ga)Se 2 films. In solution-processed CI(G)Se devices as well, Na reportedly increases V OC and FF but this improvement is not correlated with the increase in N A, suggesting a different physical mechanism associated with Na in solution-based routes. In this contribution, experimental results on the role of Na addition in solution-processed CISe films and devices were reported, in which Na addition had no influence on N A nor on film composition in spite of the notable increase in the device efficiency. On the contrary, Na was found to mitigate the interfacial recombination by reducing the undesirable surface defects. Along with this understanding, Na addition in our air-processable route resulted in a CISe device with 12.83% efficiency, which is comparable to the current world record efficiency of solution-processed CISe devices. [ABSTRACT FROM AUTHOR]

Published
2018
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199. Correction: Solution-processable Li-doped transition metal oxide hole-injection layer for highly efficient quantum-dot light-emitting diodes.

Author

Shin, Jae Seung, Kim, Mingye, Ma, Jin Hyun, Jeong, Jun Hyung, Hwang, Hui Ung, Kim, Jeong Won, and Kang, Seong Jun

Abstract

Correction for 'Solution-processable Li-doped transition metal oxide hole-injection layer for highly efficient quantum-dot light-emitting diodes' by Jae Seung Shin et al., J. Mater. Chem. C, 2022, 10, 5590–5597, https://doi.org/10.1039/D1TC06117H. [ABSTRACT FROM AUTHOR]

Published
2023
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200. Low MST1/2 and negative LATS1/2 expressions are associated with poor prognosis of colorectal cancers.

Author

Jung, Jiyoon, Kim, Jeong Won, Kim, Gilhyang, and Kim, Joo Young

Subjects
*COLORECTAL cancer, *HIPPO signaling pathway, *TUMOR suppressor proteins, *CANCER prognosis, *PROTEIN kinases
Abstract

Mammalian STe20-like protein kinase 1/2 (MST1/2) and large tumor suppressor homolog 1/2 (LATS1/2) are the core components of the tumor-suppressive Hippo pathway. Dysregulation of this pathway is associated with the progression and metastasis of various cancers. However, MST1/2 and LATS1/2 expressions have not been systematically evaluated in colorectal cancers. We evaluated the clinicopathologic correlation and prognostic significance of MST1/2 and LATS1/2 immunohistochemical expressions in 327 colorectal cancer patients. Low MST1/2 expression, identified in 235 (71.9 %) cases, was significantly associated with poor differentiation (P = 0.018) and large size (P < 0.001) of the tumor. Negative LATS1/2 expression, identified in 226 (69.1 %) cases, was significantly correlated with low MST1/2 expression (P = 0.044). Low MST1/2 and negative LATS1/2 expressions were significantly associated with poor overall survivals (P = 0.015 and P = 0.038, respectively). Furthermore, the combined MST1/2lowLATS1/2negative expression group showed significantly worse overall survival than other groups (P = 0.003), and considered as an independent poor prognostic factor for colorectal cancer patients (hazard ratio = 1.720; 95 % confidence interval, 1.143–2.588; P = 0.009). Low MST1/2 and negative LATS1/2 expressions may serve as prognostic indicators in patients with colorectal cancer. [ABSTRACT FROM AUTHOR]

Published
2023
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