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대칭 형태로 기울어진 와류 생성기를 이용한 열전달 시스템 수치 해석
김정현,박성군,Kim, Jeonghyeon,Park, Sung Goon 한국가시화정보학회 2020 한국가시화정보학회지 Vol.18 No.1
Flexible structures have been adopted in heat transfer systems as vortex generators. The flexible vortex generators immersed in a flow show a self-sustained oscillatory motion, which enhances fluid mixing and heat transfer. In the present study, the vortex generators in a two-dimensional channel flow are numerically investigated, and they are symmetrically mounted on the upper and lower walls with an inclination angle. The momentum interaction and heat transfer between the flexible vortex generators and the surrounding fluid are considered by using an immersed boundary method. The inclination angle is one of the important factors in determining the flapping kinematics of the flexible vortex generators. The flapping amplitude increases as the inclination angle increases, thereby enhancing fluid mixing. The heat transfer is enhanced up to 80% comparing to the baseline channel flow.
김정현(Kim, Jeonghyeon),이상균(Lee, Sang-Gyun),이봉주(Lee, Bong Joo),김주옥(Kim, Joo ok),이청아(Lee, Cheong-ah),유조안(Yoo, Joan),김현수(Kim, Hyun-Soo) 한국아동복지학회 2022 한국아동복지학 Vol.71 No.1
이 연구는 아동학대 재발생과 관련하여 국내·외 선행연구 및 국가통계의 조작적 정의를 살펴보고, 여러 산출 방법의 특징 및 그 기준에 따른 재학대율을 비교하였다. 이 연구에서 적용한 재학대율 산출 기준은 다음과 같다. 첫째, 우리나라에서 아동학대 국가통계 산출을 위해 적용하는 동일 피해 아동에 대한 동일 행위자의 5년 내 재학대 여부, 둘째, 행위자에 대한 구분 없이 피해 아동 기준 5년 내 재학대 여부, 셋째, 최초 학대 보고 기준 1년 이내 재학대 발생이다. 비교 분석을 위해 2012년∼2020년 간 우리나라 국가아동학대정보시스템에 입력된 자료를 활용하였고, 데이터베이스 내 존재하는 오류를 살펴보고, 전처리 과정을 통해 최종 분석자료를 선정하였다. 분석 결과, 현행 동일 피해 아동/행위자 기준의 연도별 재학대율은 8.0%∼11.3%로 집계되었고, 피해 아동을 기준으로 재학대율을 산출한 결과는 11.5%∼21.7%로 약 2배 정도 차이가 나타나는 것으로 확인되었다. 발생한 차이에 대해 기준별 아동특성을 연령, 성별, 학대행위자와 피해아동과의 관계, 학대유형, 기초생활보장 수급 여부로 구분하여 살펴보았고, 산출 기준에 따른 결과 차이를 기술하였다. 한편, 동일 피해아동/행위자로 재학대율을 산출할 때는 부 혹은 모의 단독 재학대만 추정이 가능하고, 부와 모가 시간적 간격을 두고 학대한 경우는 재학대에서 제외되는 문제가 있다. 이에 대해 부모의 재학대 행위자군을 비교한 결과 부의 단독 재학대는 31.4%, 모의 단독 재학대는 22.1%, 부와 모로 이루어진 재학대는 38.4%로 부와 모로 이루어진 경우의 비율이 가장 높았다. 즉, 현재의 재학대 기준으로는 부 혹은 모의 단독 재학대에 개입을 요구하는 결과를 낳는 오류를 범할 수 있다. 따라서, 이 연구 결과를 바탕으로 아동학대 재발생에 대한 기준을 재정립할 것을 제언하고, 이를 근거로 한 아동보호서비스에 대한 실천적 논의를 제시하였다. This study examined the operational definitions of child maltreatment recurrence by reviewing Korean and foreign literature and national statistics. We compared the characteristics of various calculation methods and recurrence rates of child maltreatment according to their standards. In this study, the criteria for calculating recurrence rates of child maltreatment were (a) whether the same perpetrator has re-abused the same child within five years (applied in Korean national statistics on child abuse); (b) whether the child victim has been re-abused within five years, regardless of the perpetrator; and (c) whether child maltreatment recurs within one year of receipt of the initial report. For comparative analysis, we employed data of the Korean Child Protective Services (CPS) from 2012 to 2020, examined errors existing in the database, and selected the data for final analysis through a rigorous pre-processing process. The results of the analysis showed that the current child maltreatment recurrence rate for the same child victim/perpetrator was 8.0%-11.3% annually, and this rate based solely on the child victim was 11.5%-21.7%, approximately twice that of the same child victim/perpetrator. We examined differences in childrens characteristics across standards by age, gender, relationship to the perpetrator, type of abuse, and receipt of National Basic Likelihood Security, and we discussed these differences according to the calculation criteria. When calculating the recurrence rates of child maltreatment for the same child victim/perpetrator, we included the re-abuse rate only when it was a single perpetrator and either the childs father or mother. Thus, if the father and mother perpetrated the abuse at different intervals, this excluded them from the recurrence of child maltreatment. The results of the comparitive analysis of groups of parental perpetrators showed thatthe fathers re-abuse rate was 31.4%, that of the mother was 22.1%, and that of both parents was 38.4%. Our results indicate that there is a need to reconsider the definitions of child maltreatment recurrence and initiate a practical discussion on child protection services.
김정현 ( Jeonghyeon Kim ),이인환 ( Inhwan Lee ),강현식 ( Hyunsik Kang ) 한국운동생리학회(구 한국운동과학회) 2021 운동과학 Vol.30 No.2
PURPOSE: This study aimed to examine the association between estimated cardiorespiratory fitness (eCRF) and sarcopenic obesity in Korean middle-aged and older adults. METHODS: This study used the data from the 2008-2011 Korea National Health and Nutrition Examination Survey involving 8,252 Korean adults aged ≥50 years (56.6% women). Participants were classified into normal, sarcopenia, obesity, and sarcopenic obesity groups based on the presence of sarcopenia and/or obesity phenotypes. eCRF was assessed using sex-specific algorithms and classified as low (lowest 25%), middle (middle 50%), and high (highest 25%) categories. Logistic regression analyses were used to estimate the odds ratio (OR) and 95% confidence interval (CI) for the risk of sarcopenic obesity according to eCRF categories. RESULTS: The middle and low eCRF groups had a significantly higher risk of sarcopenia (OR=1.688, 95% CI=1.438-1.981 and OR=2.877, 95% CI=2.366-3.498; respectively) than the high eCRF group (OR=1), a significantly higher risk of obesity (OR=1.810, 95% CI=1.533-2.137 and OR=5.103, 95% CI=4.234-6.151; respectively) than the high eCRF group (OR=1), and a significantly higher risk of sarcopenic obesity (OR=2.852, 95% CI=2.371-3.429 and OR=12.008, 95% CI=9.866-14.616; respectively) than the high eCRF group (OR=1). The risks of sarcopenia, obesity, and sarcopenic obesity in the middle and low eCRF groups remained statistically significant after adjusting for all the measured covariates. CONCLUSION: The results suggest that eCRF is an independent predictor of sarcopenic obesity in Korean middle-aged and older adults, implying the importance of promotion of CRF as a preventive measure against sarcopenic obesity.