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.

차량 모델의 복잡성이 차량동력학 해석에 미치는 영향: 모델의 비교 및 검증

배상우(Sangwoo &e),윤중락(Jung Rak Yun),이장무(Jang Moo Lee),탁태오(Tae Oh Tak) 한국자동차공학회 2000 한국 자동차공학회논문집 Vol.8 No.6

Estimated impact of the national hepatitis B immunization program on acute viral hepatitis B among adolescents in Republic of Korea

Chungman Chae,Sangwoo Tak 질병관리본부 2023 Osong Public Health and Research Persptectives Vol.14 No.2

Objectives: We aimed to estimate the impact of the national hepatitis B immunization program on the incidence of acute hepatitis B infection among adolescents in South Korea.Methods: We estimated the counterfactual incidence rate of reported acute hepatitis B among adolescents from 2016 to 2020 compared to the assumption that the national hepatitis B immunization program for children had not been implemented since 1995. The impact of the national hepatitis B immunization program for adolescents was measured by estimating the absolute risk reduction and averted acute hepatitis B infections among adolescents from 2016 to 2020 attributed to the national immunization program.Results: The relative risk reduction of acute hepatitis B among adolescents was estimated to be 83.5% after implementing the national hepatitis B immunization program. The incidence rate of reported acute hepatitis B infections among adolescents decreased from 0.39 to 0.06 per 100,000 person-years, and 43 acute hepatitis B infections, including 17 symptomatic cases, were averted annually from 2016 to 2020 by the national hepatitis B immunization program.Conclusion: The national hepatitis B immunization program for children was effective in preventing acute hepatitis B infection among adolescents in South Korea.

한국군 감염병 감시체계에 대한 고찰과 제언

이철우 ( Rhee Chulwoo ),탁상우 ( Tak Sangwoo ),강인순 ( Kang Insoon ),엄유식 ( Eom Yu Sik ),이수진 ( Lee Su-jin ),윤창교 ( Yoon Changgyo ) 국군의무사령부 2015 대한군진의학학술지 Vol.46 No.1

Recent emerging infectious disease outbreaks at an unprecedented frequency have demonstrated their potential threats to Armed Forces in Republic of Korea. Beyond the pandemics and other emerging infectious disease, bioterrorism also remains as an enduring threat to the safety of military personnels. In order to better our force protection and early response to all hazards, Armed Forces Medical Command under Ministry of National Defense needs to expand their role in disease surveillance. Domestic approaches to enhance disease surveillance is mainly led by Korean Center for Disease Control and Prevention (KCDC). KCDC operates Notifiable Disease Reporting System as well as Emergency Room Syndromic Surveillance System and Infectious Disease Specialist Network. Armed Forces Medical Command also operates similar disease surveillance system as well. However periodic evaluation and methods for dissemination invites further improvements within military surveillance environment. By taking advantages of the current military information technologies and public health infrastructure as well as leveraging other civilian efforts, Armed Forces Medical Command can optimize their disease surveillance capabilities. Through these effort, public health preparedness and response of military will be greatly improved.

Association between face covering policies and the incidence of coronavirus disease 2019 in European countries

Sookhyun Kim,Jiyoung Oh,Tak Sangwoo 질병관리본부 2023 Osong Public Health and Research Persptectives Vol.14 No.1

Objectives: This study was conducted to determine the impact of the strengthening or relaxation of face covering mandates on the subsequent national case incidence of coronavirus disease 2019 (COVID-19) in Europe as the full vaccination rate was increasing. Methods: European countries in which case incidence increased for 3 consecutive weeks were monitored and analyzed using COVID-19 incidence data shared by the World Health Organization (WHO). The epidemic trend of COVID-19 in Europe was compared with that of countries elsewhere in the world based on WHO weekly epidemiological reports from June 20 to October 30, 2021. In addition, this study provided insight into the impact of government mask mandates on COVID-19 incidence in Europe by measuring the index scores of those facial covering policies before and after mandate relaxation or strengthening. The effects of the vaccination rate and the speed of vaccination on COVID-19 incidence were also analyzed. Results: The incidence of COVID-19 after the relaxation of face covering mandates was significantly higher than before relaxation. However, no significant difference was observed in vaccination rate between countries with increased and decreased incidence. Instead, rapid vaccination delayed the resurgence in incidence. Conclusion: The findings suggest that face covering policies in conjunction with rapid vaccination efforts are essential to help mitigate the spread of COVID-19.

Dynamics of the COVID-19 epidemic in the post-vaccination period in Korea: a rapid assessment

Kyung-Duk Min,Sangwoo Tak 한국역학회 2021 Epidemiology and Health Vol.43 No.-

OBJECTIVES: Coronavirus disease 2019 (COVID-19) has had a tremendous impact on public health and socioeconomic conditions globally. Although non-pharmaceutical interventions (NPIs) such as social distancing effectively reduced the incidence of COVID-19, especially in Korea, demand for vaccination has increased to minimize the social costs of NPIs. This study estimated the potential benefits of COVID-19 vaccination in Korea. METHODS: A mathematical model with vaccinated–susceptible–latent–infectious–recovered compartments was used to simulate the COVID-19 epidemic. The compartments were stratified into age groups of 0-19 years, 20-59 years, and 60 years or older. Based on the Korea Disease Control and Prevention Agency national vaccination plan for the second quarter of 2021, announced on March 15, we developed vaccination scenarios (with 150,000 dose/d and 100% compliance as the main scenario). Comparing scenarios without vaccination or with higher/lower vaccination rates and compliance, we estimated the numbers of COVID-19 cases that will be prevented by vaccination. RESULTS: The results projected 203,135 cases within a year after April 2021 without vaccination, which would be reduced to 71,248 (64.9% decrease) by vaccination. Supposing a vaccination rate of 150,000 dose/d and 100% compliance, social distancing interventions for those aged 20 or more can be retracted after January 1, 2022. CONCLUSIONS: We expect COVID-19 vaccination to be effective in Korea. Health authorities should minimize delays in vaccination and vaccine avoidance to maximize the effectiveness of vaccination and end social distancing early.

A Nonvolatile Memory Device Made of a Ferroelectric Polymer Gate Nanodot and a Single-Walled Carbon Nanotube

Son, Jong Yeog,Ryu, Sangwoo,Park, Yoon-Cheol,Lim, Yun-Tak,Shin, Yun-Sok,Shin, Young-Han,Jang, Hyun Myung American Chemical Society 2010 ACS NANO Vol.4 No.12

<P>We demonstrate a field-effect nonvolatile memory device made of a ferroelectric copolymer gate nanodot and a single-walled carbon nanotube (SW-CNT). A position-controlled dip-pen nanolithography was performed to deposit a poly(vinylidene fluoride-ran-trifluoroethylene) (PVDF-TrFE) nanodot onto the SW-CNT channel with both a source and drain for field-effect transistor (FET) function. PVDF-TrFE was chosen as a gate dielectric nanodot in order to efficiently exploit its bipolar chemical nature. A piezoelectric force microscopy study confirmed the canonical ferroelectric responses of the PVDF-TrFE nanodot fabricated at the center of the SW-CNT channel. The two distinct ferroelectric polarization states with the stable current retention and fatigue-resistant characteristics make the present PVDF-TrFE-based FET suitable for nonvolatile memory applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2010/ancac3.2010.4.issue-12/nn1021296/production/images/medium/nn-2010-021296_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn1021296'>ACS Electronic Supporting Info</A></P>

[차량운동성능부문] 5링크식 멀티링크 현가장치의 설계와 실험차량에의 적용

윤중락(Jung Rak Yun),배상우(Sangwoo Bae),이장무(Jang Moo Lee),탁태오(Tae Oh Tak) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Multi-link, suspension consists of five links which connect wheel and chassis with spherical joints or bushings. In kinematic point of view, multi-link suspension is considered as five spherical-spherical joints, i.e. five disptance constraints, and makes wheel to have one kinematic degree-of-freedom. This suspension has many advantages in kinematic design stage because it has many design variables and optimized design can be achieved to meet designer's needs.<br/> We developed conventional five-link type multi-link rear suspension with two design stages. First stage is the kinematic geometry design stage. In this stage, this new suspension must meet some kinematic constraints, such as toe change, camber change and roll center height change. Second stage is the compliance design stage. In this stage, bushings are selected by optimization technique. This mu1ti-link suspension is adapted to modular experimental vehicle, and validated by road test

Reconstructing a COVID-19 outbreak within a religious group using social network analysis simulation in Korea

Namje Kim,Su Jin Kang,Sangwoo Tak 한국역학회 2021 Epidemiology and Health Vol.43 No.-

OBJECTIVES: We reconstructed a coronavirus disease 2019 (COVID-19) outbreak to examine how a large cluster at a church setting spread before being detected and estimate the potential effectiveness of complying with mask-wearing guidelines recommended by the government. METHODS: A mathematical model with a social network analysis (SNA) approach was used to simulate a COVID-19 outbreak. A discrete-time stochastic simulation model was used to simulate the spread of COVID-19 within the Sarang Jeil church. A counterfactual experiment using a calibrated baseline model was conducted to examine the potential benefits of complying with a mask-wearing policy. RESULTS: Simulations estimated a mask-wearing ratio of 67% at the time of the outbreak, which yielded 953.8 (95% confidence interval [CI], 937.3 to 970.4) cases and was most consistent with the confirmed data. The counterfactual experiment with 95% mask-wearing estimated an average of 45.6 (95% CI, 43.4 to 47.9) cases with a standard deviation of 20.1. The result indicated that if the church followed government mask-wearing guidelines properly, the outbreak might have been one-twentieth the size. CONCLUSIONS: SNA is an effective tool for monitoring and controlling outbreaks of COVID-19 and other infectious diseases. Although our results are based on simulations and are thus limited, the precautionary implications of social distancing and mask-wearing are still relevant. Since person-to-person contacts and interactions are unavoidable in social and economic life, it may be beneficial to develop precise measures and guidelines for particular organizations or places that are susceptible to cluster outbreaks.

Time-series comparison of COVID-19 case fatality rates across 21 countries with adjustment for multiple covariates

Kim Yongmoon,Bryan Inho Kim,Tak Sangwoo 질병관리본부 2022 Osong Public Health and Research Persptectives Vol.13 No.6

Objectives: Although it is widely used as a measure for mortality, the case fatality rate (CFR) of coronavirus disease 2019 (COVID-19) can vary over time and fluctuate for many reasons other than viral characteristics. To compare the CFRs of different countries in equal measure, we estimated comparable CFRs after adjusting for multiple covariates and examined the main factors that contributed to variability in the CFRs among 21 countries.Methods: For statistical analysis, time-series cross-sectional data were collected from Our World in Data, CoVariants.org, and GISAID. Biweekly CFRs of COVID-19 were estimated by pooled generalized linear squares regression models for the panel data. Covariates included the predominant virus variant, reproduction rate, vaccination, national economic status, hospital beds, diabetes prevalence, and population share of individuals older than age 65. In total, 21 countries were eligible for analysis.Results: Adjustment for covariates reduced variation in the CFRs of COVID-19 across countries and over time. Regression results showed that the dominant spread of the Omicron variant, reproduction rate, and vaccination were associated with lower country-level CFRs, whereas age, the extreme poverty rate, and diabetes prevalence were associated with higher country-level CFRs.Conclusion: A direct comparison of crude CFRs among countries may be fallacious, especially in a cross-sectional analysis. Our study presents an adjusted comparison of CFRs over time for a more proper comparison. In addition, our findings suggest that comparing CFRs among different countries without considering their context, such as the epidemic phase, medical capacity, surveillance strategy, and socio-demographic traits, should be avoided.