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127 results on '"Kang, Narae"'

4. Optimizing Temporal Weighting Functions to Improve Rainfall Prediction Accuracy in Merged Numerical Weather Prediction Models for the Korean Peninsula.

Author

Byun, Jongyun, Kim, Hyeon-Joon, Kang, Narae, Yoon, Jungsoo, Hwang, Seokhwan, and Jun, Changhyun

Subjects
NUMERICAL weather forecasting, RADAR meteorology, CLIMATE change, LEAD time (Supply chain management), PREDICTION models
Abstract

Accurate predictions are crucial for addressing the challenges posed by climate change. Given South Korea's location within the East Asian summer monsoon domain, characterized by high spatiotemporal variability, enhancing prediction accuracy for regions experiencing heavy rainfall during the summer monsoon is essential. This study aims to derive temporal weighting functions using hybrid surface rainfall radar-observation data as the target, with input from two forecast datasets: the McGill Algorithm for Precipitation Nowcasting by Lagrangian Extrapolation (MAPLE) and the KLAPS Forecast System. The results indicated that the variability in the optimized parameters closely mirrored the variability in the rainfall events, demonstrating a consistent pattern. Comparison with previous blending results, which employed event-type-based weighting functions, showed significant deviation in the average AUC (0.076) and the least deviation (0.029). The optimized temporal weighting function effectively mitigated the limitations associated with varying forecast lead times in individual datasets, with RMSE values of 0.884 for the 1 h lead time of KLFS and 2.295 for the 4–6 h lead time of MAPLE. This blending methodology, incorporating temporal weighting functions, considers the temporal patterns in various forecast datasets, markedly reducing computational cost while addressing the temporal challenges of existing forecast data. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Photoluminescence Quenching in Single-layer MoS2 via Oxygen Plasma Treatment

Author

Kang, Narae, Paudel, Hari P., Leuenberger, Michael N., Tetard, Laurene, and Khondaker, Saiful I.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

By creating defects via oxygen plasma treatment, we demonstrate optical properties variation of single-layer MoS2. We found that, with increasing plasma exposure time, the photoluminescence (PL) evolves from very high intensity to complete quenching, accompanied by gradual reduction and broadening of MoS2 Raman modes, indicative of distortion of the MoS2 lattice after oxygen bombardment. X-ray photoelectron spectroscopy study shows the appearance of Mo6+ peak, suggesting the creation of MoO3 disordered regions in the MoS2 flake. Finally, using band structure calculations, we demonstrate that the creation of MoO3 disordered domains upon exposure to oxygen plasma leads to a direct to indirect bandgap transition in single-layer MoS2, which explains the observed PL quenching., Comment: 12 pages, 7 figures

Published
2014

11. Electrical property tuning via defect engineering of single layer MoS2 by oxygen plasma

Author

Islam, Muhammad R., Kang, Narae, Bhanu, Udai, Paudel, Hari P., Erementchouk, Mikhail, Tetard, Laurene, Leuenberger, Michael N., and Khondaker, Saiful I.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We demonstrate that the electrical property of a single layer molybdenum disulfide (MoS2) can be significantly tuned from semiconducting to insulating regime via controlled exposure to oxygen plasma. The mobility, on-current and resistance of single layer MoS2 devices were varied up to four orders of magnitude by controlling the plasma exposure time. Raman spectroscopy, X-ray photoelectron spectroscopy and density functional theory studies suggest that the significant variation of electronic properties is caused by the creation of insulating MoO3-rich disordered domains in the MoS2 sheet upon oxygen plasma exposure, leading to an exponential variation of resistance and mobility as a function of plasma exposure time. The resistance variation calculated using an effective medium model is in excellent agreement with the measurements. The simple approach described here can be used for the fabrication of tunable two dimensional nanodevices on MoS2 and other transition metal dichalcogenides., Comment: 14 pages, 10 figures

Published
2014
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12. High Performance Semiconducting Enriched Carbon Nanotube Thin Film Transistors Using Metallic Carbon Nanotube Electrode

Author

Sarker, Biddut K., Kang, Narae, and Khondaker, Saiful I.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

High-performance solution-processed short-channel carbon nanotube (CNT) thin film transistors (TFTs) are fabricated using densely aligned arrays of metallic CNTs (m-CNTs) as source and drain electrodes, and aligned arrays of semiconducting enriched CNTs (s-CNTs) as channel material. The electrical transport measurements at room temperature show that the m-CNT contacted s-CNT array devices with a 2 um channel length perform superiorly to those of control Pd contacted s-CNT devices. The m-CNT contacted devices exhibit a maximum (average) on-conductance of 36.5 uS (19.2 uS), transconductance of 2.6 uS (1.2 uS), mobility of 51 cm2/Vs (25 cm2/Vs), and current on-off ratio of 1.1x10E6 (2.5x10E5). These values are almost an order of magnitude higher than that of control Pd contacted devices with the same channel length and s-CNT linear density. The low temperature charge transport measurements suggest that these improved performances are due to the lower charge injection barrier of m-CNT/s-CNT array devices compared to Pd/s-CNT array devices. We attribute the lower injection barrier to unique geometry of our devices. In addition to using semiconducting enriched CNT, our results suggest that using metallic CNT as an electrode can significantly enhance the performance of CNT TFTs., Comment: 14 pages, 8 figures and 1 table in main text, 2 figures and 1 table in supporting information

Published
2013
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13. The Effect of Carbon Nanotube/Organic Semiconductor Interfacial Area on the Performance of Organic Transistors

Author

Kang, Narae, Sarker, Biddut K., and Khondaker, Saiful I.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

We show that the performance of pentacene transistors can be significantly improved by maximizing the interfacial area at single walled carbon nanotube (SWCNT)/pentacene. The interfacial areas are varied by anchoring short SWCNTs of different densities (0-30/{\mu}m) to the Pd electrodes. The average mobility is increased three, six and nine times for low, medium and high SWCNT densities, respectively, compared to the devices with zero SWCNT. The current on-off ratio and on-current are increased up to 40 times and 20 times with increasing the SWCNT density. We explain the improved device performance using reduced barrier height of SWCNT/pentacene interface., Comment: 9 pages, 7 figures, 1 table

Published
2012
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27. Generation of radar rainfall ensemble using probabilistic approach

Author

Kang, Narae·Joo, Hongjun·Lee, Myungjin·Kim, Hung Soo

Subjects
010504 meteorology & atmospheric sciences, Meteorology, 0208 environmental biotechnology, Probabilistic logic, Environmental science, 02 engineering and technology, Radar rainfall, 01 natural sciences, 020801 environmental engineering, 0105 earth and related environmental sciences
Published
2017

32. Effects of Dietary Habits on Sleep Duration in Korean Adolescents: Based on Results from the 2016 Korean Youth Risk Behavior Web-based Survey

Author

강나래 ( Kang Narae ), 김남희 ( Kim Namhee ), and 이보경 ( Lee Bo Gyeong )

Subjects
0301 basic medicine, Community and Home Care, Analysis of covariance, 030109 nutrition & dietetics, Nursing (miscellaneous), Health (social science), business.industry, Public Health, Environmental and Occupational Health, Risk behavior, 030209 endocrinology & metabolism, Healthy eating, 03 medical and health sciences, 0302 clinical medicine, Secondary analysis, Medicine, Ordered logit, business, Demography, Sleep duration
Abstract

Purpose: The purpose of this study is to identify the dietary habits of Korean adolescents and to investigate their effects on sleep duration. Methods: This study is a secondary analysis drawn from the 2016 Korean Youth Risk Behavior Web-Based Survey (N=65,528). ANCOVA was used to determine the relationship between dietary habits and sleep duration. Ordinal logistic regression was used to find out the effects of dietary habits on sleep duration adjusted for general characteristics and behavioral characteristics. Results: The group that consumed no breakfast (AOR=0.89, p

Published
2018

42. Blood Glucose Control and Related Factors at a Camp for Korean Children and Adolescents with Type 1 Diabetes.

Author

Kang, Narae, Lee, Jieun, Park, Dong-Ho, Lee, Soo-Kyung, Nam, So-Young, Lee, Sanghyun, Kim, Mincheol, Kang, Heesook, Kim, Euiyeon, Kim, Misoon, and Sohn, Min

Subjects
*BLOOD sugar, *CAMPS, *STATISTICAL correlation, *DIABETES, *GLYCOSYLATED hemoglobin, *TYPE 1 diabetes, *RESEARCH methodology, *PATIENT education, *RESEARCH funding, *STATISTICS, *DATA analysis, *MULTIPLE regression analysis, *DATA analysis software, *DESCRIPTIVE statistics, *GLYCEMIC control
Abstract

Data about Asian children and adolescents with type 1 diabetes are sparse. This study’s objectives were to describe blood glucose (BG) levels and related factors at a camp for Korean children and adolescents with type 1 diabetes. This descriptive study was conducted January 8–10, 2015. The participants, 24 children and adolescents, were recruited for a 3-day residential diabetes camp. Data on 24 campers were analyzed. Their mean age was 13.4 (± 1.7) years; 44.4% were boys, and mean HgbA1c was 8.5% (± 1.4%). Results revealed that BG levels were maintained safely: The mean BG level during the 3-day stay was 171.1 (± 33.3) mg/dl. Multiple regression analysis showed that insulin adjustment for hyperglycemia (standardizedβ= .426;t= 2.431;p= .030) and snacks for hypoglycemia (standardizedβ= –.719;t= –3.723;p= .003) at the camp were the only independent contributors to mean BG levels during the 3-day study period. No demographic or clinical factor was found to be associated with the mean BG level. This is the first study of its kind to be conducted in an Asian population, presumably because the prevalence of type 1 diabetes in Asia is low and diabetes camps are a novel concept. Further research is recommended to assess the characteristics of campers (e.g., diet, activity levels, and cultural background) and to determine how the health outcomes of children and adolescents with type 1 diabetes are affected by camp programs. [ABSTRACT FROM PUBLISHER]

Published
2018
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