http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
The Evolving Policy Debate on Border Closure in Korea
Su-Jin Kang,Jihyun Moon,Heewon Kang,Heekyoung Nam,Sangwoo Tak,Sung-Il Cho 대한예방의학회 2020 Journal of Preventive Medicine and Public Health Vol.53 No.5
302 Copyright © 2020 The Korean Society for Preventive Medicine J Prev Med Public Health 2020;53:302-306 • https://doi.org/10.3961/jpmph.20.213 The Evolving Policy Debate on Border Closure in Korea SuJin Kang1, Jihyun Moon2, Heewon Kang1, Heekyoung Nam3, Sangwoo Tak1, Sung-il Cho1,3 1Institute of Health and Environment, Seoul National University, Seoul, Korea; 2Samsung Advanced Institute of Health Science and Technology, Sungkyunkwan University, Seoul, Korea; 3Department of Public Health Sciences, Graduate School of Public Health, Seoul National University, Seoul, Korea Brief Report Objectives: In this paper, we aimed to investigate the evolving debate over border closure in Korea during the coronavirus disease 2019 (COVID-19) pandemic, to address the main themes associated with border closure, and to discuss the factors that need to be considered when making such decisions. Methods: We collated and reviewed previously conducted review studies on border closures during infectious disease outbreaks to derive relevant themes and factors. Results: According to our systematic review on border closures and travel restrictions, the effects of such containment efforts are limited. We suggest considering the following factors when determining whether to impose border closure measures: (1) disease characteristics, (2) timeliness of implementation, (3) transmission delay and the basic reproduction number, (4) globalization and pandemics, and (5) social and economic costs. Conclusions: Our assessment indicates that the effects of border closures are at best temporary and limited. Alternative measures must be contemplated and implemented to suppress the spread of COVID-19 in particular and infectious diseases more broadly.
Predicting Failure Modes of Resistance Spot Welds from the Chemical Composition of Materials
Heewon Cho(조희원),Sangwoo Nam(남상우),Minjung Kang(강민정),Munjin Kang(강문진),Young-Min Kim(김영민) 대한용접·접합학회 2020 대한용접·접합학회지 Vol.38 No.5
The failure mode of resistance spot welds on steel sheets was predicted according to the chemical composition of the materials. Resistance spot welding was performed on various steels sheets ranging from 440 to 1180 MPa grade steel. Tensile strength tests were performed, and the size and hardness of the nuggets were measured to analyze the mechanical properties of the welds. The hardness values of the fusion zone and heat affected zone were determined on the basis of the chemical composition of the materials. The interfacial and pull-out-failure-generated loads were calculated and compared to predict the failure mode of the welds. The failure mode prediction results demonstrated a trend analogous to the experimental results.
Heewon Choi,Nam-gyu Lim,Seong Jun Lee,Jungsoo Park 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6
The cathode active material, which is one of the four elements constituting a lithium-ion battery (LIB), determines the capacity and power of the battery, making it an important factor that determines the performance of the battery. In this study, NCM, LFP, and LMO, which are representative cathode active materials of LIBs based on electrochemistry, were applied to 18650 cylindrical battery cells. They were expanded to a battery pack model to be mounted on an electric vehicle (EV) to compare and analyze the battery performance according to the application of different cathode active materials. The battery modeling was based on a database provided by the Gamma Technologies LIB simulation, GT-AutoLion. To analyze the thermal stability according to the temperature and the capacity loss of the battery cell resulting from the different C-rate discharges for each positive electrode active material, an electrochemical-based 1D analysis was performed.
남진현(Jinhyun Nam),계희원(Heewon Kye) 한국컴퓨터그래픽스학회 2015 컴퓨터그래픽스학회논문지 Vol.21 No.3
본 연구는 전역 조명 기법 중 하나인 환경-광 가림(ambient occlusion)을 이용한 볼륨 렌더링 방법을 설명한다. 볼륨 밀도 분포를 정규 분포로 가정하여, 환경-광 가림을 불투명도 전이함수의 변경과 무관하게 실시간 가시화할 수 있다. 전처리 과정에서 각 복셀 주변의 일정 크기 영역의 평균과 표준편차를 계산하여 두고, 가시화 단계에서 근방의 불투명도를 추정하여 밝기를 계산한다. 이 논문은 본 연구자들의 기존 연구를 발전시켜 이론적 모델을 일반화하고 출력 영상의 화질을 향상시킨다. 구체적으로 다양한 형태의 불투명도 전이함수를 사용할 수 있는 계산 모델을 제안한다. 그리고 영역의 크기를 다양하게 통계량을 생성하여 근처의 물체에 더 높은 가중치를 부여할 수 있도록 하였다. 최종적으로 환경-광 가림 효과와 지역 조명 효과를 혼합하여, 더 현실감 있는 화질의 볼륨 가시화 영상을 실시간으로 생성할 수 있다. This study presents a volume rendering method using ambient occlusion which is one of global illumination methods. By considering the volume density distribution as normal distribution, ambient occlusion can be calculated at real-time speed regardless of modification of opacity transfer function. We calculate and store the averages and standard deviations of densities in a block centered at each voxel in pre-processing time. In rendering process, we determine the illumination value by estimating the nearby opacity. We generalized theoretical model and generated better quality images improving our previous research. In detail, various shapes of transfer function can be used due to the proposed equation model. Moreover, we introduced a multi-range model to give nearer objects more weight. As the result, more realistic volume rendering image can be generated at real-time speed by mixing local and ambient occlusion shading.