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제한적인 등교 상황에서 중고등학생의 신체적·정신적 건강 및 식생활 행태 변화:COVID-19 발생 전후 2019년과 2020년의 국민건강영양조사 자료의 비교를 바탕으로
손민지,윤은주 한국식품조리과학회 2023 한국식품조리과학회지 Vol.39 No.3
Purpose: School food services have been severely affected by the COVID-19 pandemic. To determine the impact of the pandemic, this study compares the dietary behavior and perceived health status of Korean middle and high school students in 2019 and 2020, using data from the Korea National Health and Nutrition Examination Survey. Methods: Considering the nature of the data, complex sample analyses were performed. A total of 583 subjects from the 2019 and 2020 KNHANES were included in the study. Diet- and health-related variable behaviors were compared separately for boys and girls. Nutrient intake was compared after adjusting the consumed calories using the 24-hour recall data. Quality of the nutrient intake was compared against the 2020 Dietary Reference Intakes for Koreans. Results: After the outbreak of COVID-19, students were more likely to skip breakfast and less likely to eat out. In 2020, the physical activity was lowered but the weight control effort remained similar to 2019. Although the percentage of students with alcohol consumption decreased in 2020, the overall number of heavy drinkers increased among consumers. Compared to 2019, the proportion of female smokers quadrupled in 2020 and the frequency and the amount of male student smokers also increased significantly. Changes in the nutrient intake differed between male and female students. Conclusion: U sing t he s econdary d ata, this study found t hat the COVID-19 pandemic affected the dietary- and health-related behaviors of students. We recommend that the impact and circumstances of these changes should be investigated in more depth.
Maximum production of methanol in a pilot-scale process
손민지,박명준,곽근재,박해구,전기원 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.2
Mathematical models for both bench- and pilot-scale methanol synthesis reactors were developed by estimating the overall heat transfer coefficients due to different heat transfer characteristics, while the effectiveness factor was fixed because the same catalysts were used in both reactors. The overall heat transfer coefficient of a pilot-scale reactor was approximately twice that of a bench-scale reactor, while the estimate from the correlation reported for the heat transfer coefficient was 1.8-times higher, indicating that the values determined in the present study are effective. The model showed that the maximum methanol production rate of approximately 16 tons per day was achievable with peak temperature maintained below 250 oC in the open-loop case. Meanwhile, when the recycle was used to prevent the loss of unreacted gas, peak temperature and production rate decreased due to low CO and CO2 fraction in the recycled stream at the same space velocity as the open-loop operation. Further analysis showed that, since the reaction was in the kinetic regime, the production rate could be maximized up to 18.7 tons per day by increasing the feed flowrate and inlet temperature despite thermodynamically exothermic reaction.
Impact of COVID-19 and Associated Preventive Measures on Cardiometabolic Risk Factors in South Korea
손민지,구보경,윤호일,Kyoung-Ho Song,김의석,김홍빈,임수 대한비만학회 2021 Journal of obesity & metabolic syndrome Vol.30 No.3
Background: During the coronavirus disease 2019 (COVID-19) pandemic, preventive measures mandated by government policies have included the closure of exercise facilities and movement restriction, which can lead to an unhealthy lifestyle. We investigated the effect of these preventive measures on metabolic parameters in individuals with cardiometabolic disorders. Methods: In this retrospective, observational study of patients who visited the hospital at least twice a year for the past 4 years, changes in cardiometabolic factors during the COVID-19 pandemic (2019–2020) were compared with changes in the same cohort at the same annual time points during the previous seasons of 2016–2019. Results: A total of 1,485 individuals with a mean age of 61.8±11.7 years were included in the analyses. During the COVID-19 pandemic, the number of patients whose metabolic syndrome worsened increased significantly by 21% compared with the 2018–2019 season. Body mass index increased by 0.09±1.16 kg/m2 in the 2019–2020 pandemic period, whereas it decreased by –0.39±3.03 kg/m2 in 2018–2019 and by –0.34±2.18 kg/m2 in 2017–2018 (both P<0.05). Systolic blood pressure increased by 2.6±18.2 mmHg in the COVID-19 pandemic period, while it decreased in the three antecedent seasons (all P<0.05). Lipid profiles worsened in the pandemic period compared with the previous years. Framingham coronary heart disease risk score also increased significantly. Conclusion: Nationwide strategies to maintain cardiometabolic health are necessary during contagious disease pandemics like COVID-19 to mitigate the adverse health effects of pandemic-preventative strategies.
손민지,권명준,조승주,김창익 대한전자공학회 2022 전자공학회논문지 Vol.59 No.10
합성곱 신경망은 컴퓨터 비전 분야에서 뛰어난 성능을 보이고 있지만 눈에 띄지 않는 잡음이 추가된 적대적 예제에 취약하다. 적대적 예제에 대한 취약성은 보안, 안전이 중요한 분야에서 심각한 문제를 일으킬 수 있다. 따라서 신경망이 상용화되기 전 취약성을 확인하여 위협에 대비하기 위해 적대적 공격에 대한 연구가 활발히 진행되고 있다. 타겟 모델의 내부 구조가 숨겨져 있는 상황에서는 공격자가 자신이 가지고 있는 소스 모델을 사용하여 적대적 예제를 생성하고, 그 이미지가 타겟 모델도 교란하기를 기대하는 전이성 기반 공격을 수행할 수 있다. 이러한 공격의 전이성을 향상시키기 위해 지금까지 제안된 입력 다변화 방법은 모든 픽셀에 같은 변환을 가하여 상대적으로 적은 전이성 향상을 보인다. 이에 본 논문은 입력 이미지의 각 픽셀을 재배치하여 전이성이 높은 적대적 예제를 생성하는 방법을 제안한다. 좀 더 상세히 말하면, 다양한 방향의 왜곡을 표현할 수 있는 탄성 변환을 사용하여 입력의 다양성을 확대하고 적대적 예제가 소스 모델에 과적합되는 것을 피한다. 우리는 이미지넷 기반 여러 분류 모델에 대한 적대적 공격 실험을 통해 탄성 변환을 사용하여 적대적 예제를 생성하는 방법이 전이성을 높이는 효과적인 방법임을 보인다.
손민지,표용수,Son, Min Ji,Pyo, Yong-Soo 영남수학회 2014 East Asian mathematical journal Vol.30 No.4
The purpose of this thesis is to analyze mathematical errors in descriptive problems of the Mathematics Level Assessment(MLA) which is conducted in P University. We classified mathematical errors, which are easily made in solving the descriptive problems of the MLA, into nine types as misused data, misinterpreted language, logically invalid inference, misunderstood theorem or definition, unmatched solution, technical errors, omission of solving process, ambiguous errors, and unattempted errors. With classifying the errors in nine types, we analyzed the errors of students, who are in intermediate and low level grades, by descriptive problems. On the basis of these analysis results, we suggest plans for improving the implementation of the MLA and the teaching-learning methods about College General Mathematics.