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 예방의학회지 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

Vehicle dynamic models in handling and stability analysis are divided into three groups: bicycle model, roll axis model and full vehicle model. Bicycle model is a simple linear model, which has two wheels with load transfer being ignored. Roll axis model treats left and right wheels independently. In this model, load transfer has a great effect on nonlinearity of tire model. Effects of suspension system can be analyzed by using full vehicle model, which is included suspension stroke motions. In this paper, these models are validated and compared through comparison with road test, and the effects of suspension kinematics and compliance characteristics on vehicle motion are analyzed. In handling and stability analysis, roll axis model can simulate the real vehicle motion more accurately than full vehicle model. Compliance steer has a significant effect, but the effect of suspension kinematics is negligible.

Factors associated with the timely diagnosis of malaria and the utilization of types of healthcare facilities: a retrospective study in the Republic of Korea

HyunJung Kim,Sangwoo Tak,So-dam Lee,Seongwoo Park,Kyungwon Hwang 질병관리청 2024 Osong Public Health and Research Persptectives Vol.15 No.2

Objectives: This study aimed to analyze trends in the timely diagnosis of malaria cases over the past 10 years in relation to the utilization of different types of healthcare facilities.Methods: The study included 3,697 confirmed and suspected cases of malaria reported between January 1, 2013, and December 31, 2022, in the national integrative disease and healthcare management system. Some cases lacking a case report or with information missing from the case report were excluded from the analysis. A generalized linear model with a Poisson distribution was constructed to estimate rate ratios and 95% confidence intervals adjusted for other variables, such as distance.Results: When cases involving diagnosis >5 days after symptom onset in confirmed patients (5DD) were examined according to the type of healthcare facility, the rate ratio of 5DD cases was found to be higher for public health facilities than for tertiary hospitals. Specifically, the rate ratio was higher when the diagnosis was established at a tertiary hospital, even after a participant had visited primary or secondary hospitals. In an analysis adjusted for the distance to each participant’s healthcare facility, the results did not differ substantially from the results of the crude analysis.Conclusion: It is imperative to improve the diagnostic capabilities of public facilities and raise awareness of malaria at primary healthcare facilities for effective prevention and control.

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.

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>

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.

Evaluation of the acute hepatitis B surveillance system in the Republic of Korea following the transition to mandatory surveillance

Chung Jaehwa,Yu Jeonghee,Cheon Myeongeun,Tak Sangwoo 질병관리청 2024 Osong Public Health and Research Persptectives Vol.15 No.4

Objectives: The prevalence of hepatitis B in the Republic of Korea has declined, yet the disease burden persists. After various changes in targets and methods, the national hepatitis B surveillance system now exclusively monitors acute cases. We aimed to assess the alignment of this system with its intended purpose and to recommend improvements supporting the national strategic plan for viral hepatitis management.Methods: This study assessed acute hepatitis B cases reported to the Korean Disease Control and Prevention Agency’s mandatory surveillance system over a 10-year period (2013–2022). It evaluated 5 factors from the Centers for Disease Control and Prevention’s Updated Guidelines for Evaluating Public Health Surveillance Systems: simplicity, positive predictive value, data quality, timeliness, and usefulness.Results: The nonspecific nature of acute hepatitis B symptoms, along with the complexity of diagnostic criteria, indicated a high potential for misreporting. The surveillance system demonstrated a high positive predictive value (94.4%), with data quality and timeliness also rated high. However, data following the onset of the coronavirus disease 2019 pandemic indicate the need for improvement. Moreover, given the relative importance of specific characteristics of chronic infectious diseases, only limited interventions are implementable through the current surveillance system.Conclusion: The evaluation of the Republic of Korea’s acute hepatitis B surveillance system revealed high positive predictive value, data quality, and timeliness. However, improvements can be made in the misreporting of chronic cases and the system’s usefulness. More accurate reflection of the characteristics of acute hepatitis B cases is essential for better management of viral hepatitis.

[응용논문] 도로이탈방지 시스템의 운전자 간섭에 대한 연구

장승붕(Shengpeng Zhang),허효영(Hyoyeong Heo),안상우(Sangwoo Ahn),탁태오(Taeoh Tak) 한국자동차공학회 2021 한국 자동차공학회논문집 Vol.29 No.4

The article deals with the analysis of driver interaction based on the road departure prevention system(RDPS). Firstly, the controller of the RDPS, which uses the linear quadratic regulator(LQR) method, is modeled. The controller is identified by the two-degree-of-freedom vehicle model and the steering model. The various weight coefficients of LQR are investigated through the vehicle driving trajectory. The performances of the RDPS model are validated with various lateral velocities in the straight road and the curved road, respectively. Then, the driver interaction based on RDPS is carried out in the driving simulator. The motion of the driver is analyzed by using motion capture devices. The results show that the vehicle is unstable when the driver intervenes with the RDPS. Also, when the RDPS was intervened by the driver, the right curved road was more unstable than the left curved road.