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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.
코로나 플라즈마 처리에 의한 HDPE 표면의 개질에 관한 연구
최진숙,전종탁,정봉규,이근대,문명준,이종무 釜慶大學校 2001 釜慶大學校 論文集 Vol.6 No.-
We are able to generate the stable plasma in open air and nitrogen using a corona plasma treatment system(CPTS) with a high voltage. This was applied to treat the surface of rather non-polar HDPE(High Density Polyethylene) intended for the improvement of adhesion of over-coated layers such as coatings, printing inks. The surface tension of HDPE was significantly improved by the CPTS. The characteristics of surface layer were evaluated by means of contact angle measurement, ATR-FT/IR spectroscopy, and it was found that functional groups were introduced into the surface layer of the HDPE. The use of nitrogen was increased the surface tension of the HDPE from 33.8 mJ/m^2 to 66.56 mJ/m^2, and highly effective method of HDPE surface modification could be realized.
The Thermal Properties of PVC-Ni Composite Materials
Moon, Tak-Jin,Kang Chang-Gyun Korean Chemical Society 1985 Bulletin of the Korean Chemical Society Vol.6 No.1
The glass transition temperature, dynamic shear moduli, and bulk viscosities of PVC, filled with nickel particles, were investigated. The glass temperature of the composite increased with increasing filler concentration. The data were interpreted by assuming that the interaction between filler particles and the polymer matrix reduces molecular mobility and flexibility of the polymer chains in the vicinity of the interfaces. The relative modulus for the PVC/Ni composite system followed the Kerner equation. The relative viscosities were strongly temperature dependent and did not agree with the conventional viscosity predictions for suspensions. It is suggested that the filler has a twofold effect on the viscosity of the composite materials; one is due to its mechanical presence and the other is due to modification of part of the polymer matrix caused by interaction. This phenomenon is approximately bounded by Kerner's predictions for suspensions.