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Choi Yunsang,Kang Minsun,Shin Dong Hoon,Jung Jongtak,Choi Seong Jin,Kim Nak-Hyun,Moon Song Mi,Song Kyoung-Ho,Kim Eu Suk,Jung Jaehun,Kim Hong Bin 대한의학회 2023 Journal of Korean medical science Vol.38 No.25
Background: Although coronavirus disease 2019 (COVID-19) is a viral infection, antibiotics are often prescribed due to concerns about accompanying bacterial infection. Therefore, we aimed to analyze the number of patients with COVID-19 who received antibiotic prescriptions, as well as factors that influenced antibiotics prescription, using the National Health Insurance System database. Methods: We retrospectively reviewed claims data for adults aged ≥ 19 years hospitalized for COVID-19 from December 1, 2019 to December 31, 2020. According to the National Institutes of Health guidelines for severity classification, we calculated the proportion of patients who received antibiotics and the number of days of therapy per 1,000 patient-days. Factors contributing to antibiotic use were determined using linear regression analysis. In addition, antibiotic prescription data for patients with influenza hospitalized from 2018 to 2021 were compared with those for patients with COVID-19, using an integrated database from Korea Disease Control and Prevention Agency-COVID19-National Health Insurance Service cohort (K-COV-N cohort), which was partially adjusted and obtained from October 2020 to December 2021. Results: Of the 55,228 patients, 46.6% were males, 55.9% were aged ≥ 50 years, and most patients (88.7%) had no underlying diseases. The majority (84.3%; n = 46,576) were classified as having mild-to-moderate illness, with 11.2% (n = 6,168) and 4.5% (n = 2,484) having severe and critical illness, respectively. Antibiotics were prescribed to 27.3% (n = 15,081) of the total study population, and to 73.8%, 87.6%, and 17.9% of patients with severe, critical, and mild-to-moderate illness, respectively. Fluoroquinolones were the most commonly prescribed antibiotics (15.1%; n = 8,348), followed by third-generation cephalosporins (10.4%; n = 5,729) and beta-lactam/beta-lactamase inhibitors (6.9%; n = 3,822). Older age, COVID-19 severity, and underlying medical conditions contributed significantly to antibiotic prescription requirement. The antibiotic use rate was higher in the influenza group (57.1%) than in the total COVID-19 patient group (21.2%), and higher in severe-to-critical COVID-19 cases (66.6%) than in influenza cases. Conclusion: Although most patients with COVID-19 had mild to moderate illness, more than a quarter were prescribed antibiotics. Judicious use of antibiotics is necessary for patients with COVID-19, considering the severity of disease and risk of bacterial co-infection.
XML 변경 유효성 검증을 위한 경계락킹에 기초한 시퀀스 그룹 검증기법
최윤상(Yunsang Choi),박석(Seog Park) 한국정보과학회 2004 한국정보과학회 학술발표논문집 Vol.31 No.2Ⅱ
DTD에 의해서 문서의 형식이 정의된 valid XML을 XML 데이터베이스 시스템을 사용하여 관리하는 경우 XML의 변경은 그 변경 결과가 DTD에 대한 유효성(validity)을 만족시킬 때에만 수행되어야 한다. 이것은 다수의 사용자에 의해서 데이터가 공유되는 데이터베이스 시스템의 데이터 무결성과 관련되는 문제이기 때문에 XML 문서 변경에 대한 DTD 유효성은 XML데이터베이스 시스템에서 중요한 속성이라고 할 수 있다. 변경 연산의 결과에 대한 XML의 유효성을 보장하기 위해서 변경의 유효성을 검증하는 방법을 사용할 수 있다. XML에서의 엘리먼트들은 순서 관계를 가질 수 있으며 DTD는 이러한 엘리먼트 순서 관계들을 정의하고 있기 때문에 이러한 유효성 검증 기법은 변경되는 데이터 아이템 외에도 주변의 데이터 아이템-엘리먼트-들에 대한 순서 정보를 필요로 한다. 그리고 데이터베이스와 같은 다중 사용자 환경에서 유효성 검증 기법이 정확하게 수행되기 위해서는 유효성 검증에 필요한 정보들이 다른 트랜잭션에 대해 변경되지 않도록 하는 병행수행 제어 기법을 필요로 한다. 이렇게 유효성 검증 기법과 병행수행 제어 기법이 관련을 가지고 있음에도 불구하고 기존의 유효성 검증 기법은 오직 검증의 효율성에만 초점을 맞추고 있다. 본 연구는 유효성 검증의 검증 범위를 최소화 시켜 pan-out 값이 큰 XML 문서에 대해서도 유효성 검증이 효율적으로 수행될 수 있고, 또한 유효성 검증을 위해 락킹되는 데이터 아이템의 수를 최소화 할 수 있는 시퀀스 그룹 검증 기법을 제안한다. 또한 이 검증 기법의 정확을 보장하면서도 높은 트랜잭션 병행수행 성능을 보장할 수 있는 경계 락킹 기법을 제안한다. 제안된 유효성 검증 기법과 경계 락킹 기법은 유효성 검증의 정확성을 위해 병행수행 성능이 저하될 수밖에 없는 기존의 기법들의 문제점들을 해결하여 XML 데이터베이스 시스템이 안정적인 성능을 제공할 수 있다는 것을 실험을 통해 확인할 수 있었다.
A simple and efficient color recovering system for content sharing website
Han, Yunsang,Lee, Seokhan,Choi, Jongsoo,Lee, Sangkeun IEEE 2010 IEEE transactions on consumer electronics Vol.56 No.2
<P>Lossy image data compression is commonly used to reduce the original data size on traditional lossy compression fields, such as MPEG-x and H.26x including User-Created Content. This paper proposes a simple and efficient method for correcting online user-created contents¿ distortion in color. The proposed system consisted of two main phases: 1) in the training step, the working space was converted to CIE Lab color space. Next, the training images were classified to estimate the correction matrices. The correction matrices were calculated and optimized through a Newton iteration-based approach between the original and distorted images; and 2) in the correction step, the optimized correction matrices were applied to the distorted images for the color reproduction. In order to evaluate the performance of the proposed scheme, the quantitative measures were defined in terms of the peak signal-to-noise ratio (PSNR) and correction ratio. The experimental results showed that the proposed approach can reduce significantly the color distortion from a video sharing website. The proposed method can be a useful tool for correcting the distortion caused by image processing, such as lossy compression and color improvement in the consumer electronics-related field.</P>
송윤상 ( Yunsang Song ),최양호 ( Yang Ho Choi ) 한국리스크관리학회 2023 리스크 管理硏究 Vol.34 No.4
본 연구에서는 사망 및 투자수익률의 확률론적 방법에 기초한 시나리오를 통해서 개인이 연금 대신 대안투자(자가연금)를 선택하였을 경우에 발생할 수 있는 파산확률과 손실금액을 산출하였고, 파산확률과 손실금액을 고려하여 이를 장수리스크로 정의하였다. 기존의 연구는 파산확률을 고정된 생존확률에 의존하여 산출하였고 부족금액이 발생한 시점의 부족금액을 리스크량으로 정의하였으나, 본 연구는 베르누이 분포를 이용하여 실제 사망의 분포를 산출하여 사용하였으며 각 사망 시점에서 손실금액을 평가하여 이를 리스크량으로 계량화하였다. 기존 연구는 단순히 확률에만 관심 있었다면 본 연구는 실제 확률론적 방법을 적용하였고 사망시점의 리스크량 평가까지 확대한 것에 의의가 있다. 또한 확률론적 방법에 의한 투자P/F별로 최적의 연금개시 연령을 제시하였다. In this study, we calculated the ruin probability that could occur when individuals choose self annuity plans instead of conventional annuity, based on the actual mortality rate and investment return scenarios. We defined this as longevity risk by considering both the ruin probability and the maximum loss amount. Previous research calculated the ruin probability based on fixed survival probabilities and defined the shortfall amount at the point of occurrence as the risk amount. However, in this study, we used the Bernoulli distribution to estimate the distribution of actual ages at death and quantified the loss amount at each death point as a measure of risk. While previous research was solely interested in probabilities, this study applied actual probabilistic methods and expanded the evaluation to include the risk amount at the time of death. Furthermore, we provided the optimal retirement age for each investment portfolio based on the probabilistic approach.
하향 전파하는 예혼합 화염에서 루이스 수에 따른 열음향 불안정성의 동적거동 변화
최재혁(Jae-Hyuk Choi),박순철(Soonchul Park),전윤상(Yunsang Jun),천유진(Yujin Chun),한경훈(Kyounghoon Han),윤성환(Sung Hwan Yoon) 한국연소학회 2018 한국연소학회지 Vol.23 No.3
The effects of Lewis number on acoustic instability of downward propagating flames in a tube were studied experimentally. The discussion first treated the coupling effects between cellular, Darrieus-Landau and primary acoustic instabilities in non-equidiffusive flames. Low Lewis number tended to generate stronger primary acoustic sound and to suppress cellular instability under the fixed laminar burning velocity. Also, displacement flame velocities declined with low Lewis number because of diminished flame surface area with absence of combustion instability. We then described the effects of Lewis number on secondary acoustic instability. To generate secondary acoustic instability at desired time, we adopted the CO₂ laser irradiation method to alter the shape of the flame front. The results showed that for a Lewis number below (above) unity, relatively stronger (weaker) acoustic sound is produced under the same laminar burning velocity, because the combustion wave becomes sensitive (insensitive) to pressure fluctuations in the acoustic field due to curvature effects. Therefore, shorter (longer) transition time was required from secondary acoustic instability to turbulent motion.
Can reactogenicity predict immunogenicity after COVID-19 vaccination?
( Young Hoon Hwang ),( Kyoung-ho Song ),( Yunsang Choi ),( Suryeong Go ),( Su-jin Choi ),( Jongtak Jung ),( Chang Kyung Kang ),( Pyoeng Gyun Choe ),( Nam-joong Kim ),( Wan Beom Park ),( Myoung-don Oh 대한내과학회 2021 The Korean Journal of Internal Medicine Vol.36 No.6
Background/Aims: This study aimed to assess the association between local and systemic reactogenicity and humoral immunogenicity after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. Methods: Adverse events were prospectively evaluated using an electronic diary in 135 healthy adults who received a SARS-CoV-2 vaccine (AZD1222, AstraZeneca/ Oxford, n = 42; or BNT162b2, Pfizer/BioNTech, n = 93). We semi-quantitatively measured anti-S1 immunoglobulin G (IgG) using an enzyme-linked immunosor-bent assay at baseline, 3 weeks after the first dose of AZD1222 or BNT162b2, and 2 weeks after the second dose of BNT162b2. We evaluated the association between the maximum grade of local or systemic adverse events and the anti-S1 IgG optical density using multivariate linear regression with adjustment for age, sex, and use of antipyretics. Results: The median age of the 135 vaccinees was 30 years (36 years in the AZD1222 group and 29 years in the BNT162b2 group) and 25.9% were male (9.5% in the AZD1222 group and 33.3% in the BNT162b2 group). Local and systemic adverse events were generally comparable after the first dose of AZD1222 and the second dose of BNT162b2. The grades of local and systemic adverse events were not significantly associated with anti-S1 IgG levels in the AZD1222 or BNT162b2 group. Conclusions: Local and systemic reactogenicity may not be associated with humoral immunogenicity after SARS-CoV-2 vaccination.