버블 병합 효과를 고려한 새로운 풀 핵비등 역학 모델 개발

김민창(Minchang Kim),김성진(Sung-Jin Kim) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12

A mechanistic model that includes the effect of bubble coalescence on nucleate pool boiling heat transfer is developed through experimental and theoretical investigations. Transient temperature and heat flux distributions on the boiling surface are obtained using a high-speed infrared imaging technique. According to the temperature and heat flux distributions, the boiling surface is classified into three regions: natural convection, quenching, and evaporation regions. By observing how the heat flux on each region and the corresponding area fraction change as the bubble coalescence occurs, the effect of the bubble coalescence on nucleate pool boiling is investigated. It is found that the bubble coalescence does not affect the heat fluxes on the three regions but affects the area fractions: As the bubble coalescence occurs, the rates of increase in evaporation and quenching area fractions decrease, and the natural convection area fraction remains the same. By accounting for the effect of the bubble coalescence on quenching and evaporation area fractions, a new correlation of the boiling heat flux is developed and presented. To validate the present model, the boiling curve for saturated water is reproduced and compared to experimental data.

사물인터넷 기반의 집중도 및 명상도 검출을 통한 ASMR 콘텐츠 제어 기법

김민창(Minchang Kim),서정욱(Jeongwook Seo) 한국디지털콘텐츠학회 2018 한국디지털콘텐츠학회논문지 Vol.19 No.9

슬롯제트가 플레이트 히트싱크 열성능 및 유동 균일성에 미치는 영향

김민창(Minchang Kim),도규형(Kyu Hyung Do),최병일(Byung-Il Choi),한용식(Yong-Shik Han),유화롱(Hwalong You),김창현(Changhyun Kim),김태훈(Taehoon Kim) 대한기계학회 2024 大韓機械學會論文集B Vol.48 No.3

In this study, the effects of the slot jet flow on the thermal performance of plate heat sinks are investigated. Heat sink experiments are conducted using heat sinks and heaters whose dimensions are 40 × 40 mm. A slot nozzle installed at the exit of a wind tunnel is used to form a slot jet flow that is blasted onto the plate heat sink. For the parametric study, the slot width is changed from 5 mm to 40 mm, while the fin height is changed from 5 to 20 mm. The thermal performance of the plate heat sink is evaluated using the pressure drop and thermal resistance. The experiments demonstrate the existence of an optimal slot width where the thermal resistance is minimized at the same pressure drop. Further, the optimal slot width increases with the fin height of the heat sink.

압력센서를 이용한 자세 교정 유도 스마트 방석 개발

김민창(Minchang Kim),서태영(Taeyoung Seo),이주협(Juhyeob Lee),허웅(Ung Heo),유홍석(Hongseok Yoo) 한국컴퓨터정보학회 2019 한국컴퓨터정보학회 학술발표논문집 Vol.27 No.1

장애인수영 S14등급의 국내 및 국제대회 경기기록 추이분석

김민창(Minchang Kim) 한국체육측정평가학회 2021 한국체육측정평가학회지 Vol.23 No.2

이 연구는 장애인 수영 S14등급을 대상으로 리우패럴림픽을 포함한 3년간 수행된 국제 및 국내대회의 경기기록을 비교하여 경기력 관련 정보를 생성하는 것을 목적으로 하였다. 연구목적 달성을 위해 패럴림픽 및 국제수영대회의 기록과 국내 전국장애인체육대회의 295개의 경기기록을 수집하였다. 자료처리는 기술통계와 Mann-Whitney, Friedman 검증을 수행하였다. 본 연구의 결론은 다음과 같다. 첫째, 장애인 수영 S14등급의 성별 및 모든 세부종목에서 국제대회 선수들의 경기력 수준이 높았다. 둘째, 국제 선수들의 경우 경기력에 대한 추이는 변화하였다. 국내 선수들의 경우 남자는 자유형과 배영, 여자는 자유형에서 경기력에 변화를 나타냈다. 반면, 경기력에 대한 일정한 변화의 경향성은 나타나지 않았다. 셋째, 국내 선수들의 경우 자유형 종목이 경기력 수준에 대한 편차가 가장 큰 것으로 나타났다. 이 연구는 장애인 수영 선수들의 기록에 대한 기초정보를 비롯하여 국내 및 국제선수들의 경기력과 관련한 다양한 정보로 활용될 수 있을 것이라 판단한다. The purpose of this study was to analyze the trend of international and Korean records for S14 class swimmers with intellectual disabilities. For the purposes of this study, 295 matches records of Paralympic Games, international and Korean competitions were collected. The conclusions of the study are as follows. First, the level of performance of international athletes was high in gender and all sub-categories. Second, the trend for international athletes has changed. In the case of Korean athletes, the performance was changed in freestyle and backstroke for men and freestyle for women. On the other hand, there was no tendency for constant change to the record. Third, in the case of Korean athletes, freestyle sport had the biggest deviation in performance level. The results of this study can be used in various ways as basic information on the performance of swimmers with intellectual disabilities.

특수체육교육과 학생들의 진로결정 과정 탐색

김민창 ( Minchang Kim ),한민규 ( Minkyu Han ) 한국체육대학교 체육과학연구소 2019 스포츠사이언스 Vol.36 No.2

The purpose of this study is to propose a theoretical framework for career decision of students with Special Physical Education major, by exploring the process of how they choose and decide on their career during their college life based on the grounded theory method. To do so, this study used in-depth interview applied from the Grounded Theory Analysis method by Strauss and Corbin (1996), and collected data from 10 students with Special Physical Education major. The in-depth interview mainly composed of questions on the personal background of special physical education students when choosing their career, and various factors influencing their choices. The interview responses were recorded by a recorder and transcribed. The data was analyzed through open coding, axis coding, and choice coding according to the analysis framework of Grounded Theory method proposed by Strauss and Corbin (1996). Finally, this research categorized and standardized the career decision-making process of study participants who are in the Department of Special Physical Education. The open coding analysis resulted in a total of 28 concepts, 12 subcategories, and 6 categories, and the result of axis coding analysis showed that students in the Special Physical Education major had a central phenomenon of ‘setting their career direction’ through ‘concerns over career choice.’ In setting their career direction, they used the mutual interaction strategies of ‘career exploration’ by a contextual condition of an ‘influence by the surrounding environment’ and the mediating conditions of ‘aptitude for teaching positions’ and ‘satisfaction with major.’ Through this process, they decided on their careers of ‘preparation for special teacher,’ ‘preparation for regular teacher,’ and ‘preparation for an expert of special physical education site.’ Finally, this study created hypothetical standardizations and hypothetical relationship statements in choice coding analysis and conducted typological analysis, which showed that the career decision types of students in the Special Physical Education major were: ‘department-focused preparation for teaching position,’ ‘self-directed preparation for teaching position,’ and ‘outward-oriented career pioneering type.’ This study identified the various experiences in career decision-making process of students in the Department of Special Physical Education and categorized them into different types. The study results will be able to provide basic data that can help students make an efficient career decision that fits their aptitude, and advance their time of career choice decision.

국소 열유속 및 온도 측정을 통한 물 풀 핵비등에서의 열전달 메커니즘 연구

김민창(Minchang Kim),김성진(Sung Jin Kim) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

The local heat flux and temperature on the boiling surface are measured to determine the heat transfer mechanism in nucleate pool boiling. Using infrared thermometry, the temperature distribution can be measured when mid-wave(3-5.5 ㎛) optical access to the surface is possible. The heat flux is calculated by the heat equation with this temperature information. The contact line length density(CLD) and the time-averaged wetted area fraction(WF) are also measured for an infrared opaque indium-tin-oxide surface over an electrically heated silicon substrate which is transparent to infrared. With this information, the dominant heat transfer mechanism during the nucleate pool boiling of water is evaluated. In conclusion, the convection heat transfer on the liquid area based on the micro-convection model is the predominant heat transfer mechanisms during the nucleate pool boiling of water.

중앙정부 이전재원이 시ㆍ군 기초자치단체 지역경제 성장에 미치는 영향: 도구변수를 활용한 패널회귀분석

김민창(Kim, Minchang),김애진(Kim, Aejin) 한국지방정부학회 2019 지방정부연구 Vol.23 No.3

본 연구는 2009~2015년 기간 동안 144개 시ㆍ군 기초자치단체의 자료를 활용하여 국고보조금 및 지방교부세 등의 중앙정부 이전재원이 지역경제 성장에 미친 영향을 분석하였다. 분석을 위해 도구변수를 활용한 패널 회귀분석을 실시하였으며, 1인당 GRDP 증가율로 측정한 지역경제 성장에 대해 전체 기초자치단체에 대한 분석과 함께 시ㆍ군 각 그룹별로 구분한 분석을 시도하였다. 본 연구의 분석결과 국고보조금, 지방교부세 등의 중앙정부 이전재원은 기초자치단체의 지역경제 성장에 긍정적 영향을 미치고 있음을 확인하였다. 이는 이들 이전재원이 부족한 지방정부의 재정을 보완하는 역할을 하고 있기 때문인 것으로 보인다. 중앙정부 이전재원의 활용 효율성을 높이고 지방자치단체 간 재정불균형 완화라는 제도의 목적을 달성하기 위해서는 각 기초자치단체가 자생력을 갖추기 위한 자구노력에 대해 동기를 부여할 수 있는 방향으로 이전재원 제도를 보완할 필요가 있다. 또한, 지역경제 성장을 위해 각 기초자치단체가 해당 지자체의 상황에 대응하여 지역의 인적자본 개발, 지역산업육성 강화 등의 정책 방안을 모색할 필요가 있다. This study examines the effects of the intergovernmental financial transfers such as categorical-grant and the local share tax on the regional economic growth by using the data of 144 local governments from 2009 to 2015. For this study, panel regression analysis using tool variables was performed in addition to analysis by local government on the growth of the local economy based on the GRDP increase rate per person categorized by city and province. It was confirmed in this results that resources transferred from the central government such as government subsidies and local subsidies have created a positive influence. Therefore, it is essential to improve the resource transfer system in such a way that it will foster and motivate the voluntary efforts of the local governments seeking self-sufficiency in order to accomplish the original purpose of the resource transfer system which is to pursue the efficient utilization of the resources and ease the levels of inequality among local governments. Given such conditions, it will be important for the basic local government to seek effective policy measures such as the development of human resources and the reinforcement of the local economy to overcome circumstantial weaknesses.

국소 열유속 및 온도 측정을 통한 물 풀비등에서의 임계열유속 메커니즘 연구

김민창(Minchang Kim),김성진(Sung Jin Kim) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12

In the present study, the critical heat flux (CHF) mechanism in pool boiling of water is experimentally investigated. The experiments are performed using an infrared (IR) camera to measure the temperature and heat flux distributions on the boiling surface. An IR-transparent boron-doped silicon wafer is used as the heater. Boiling takes place from an IRopaque titanium surface that is deposited on the silicon heater. The wetted area fraction (WF), the contact line length density (CLD) and the contribution of various heat transfer mechanism to overall heat transfer were measured throughout the boiling curve. Quantitative analysis of this data at high heat flux and transition through CHF revealed that the occurrence of the unquenchable dry spot triggers CHF.

깊이지각 카메라를 이용해 얻어진 3D point set 의 정밀도

김민창(MINCHANG KIM),신영길(Yeong Gil Shin) 한국정보과학회 2018 한국정보과학회 학술발표논문집 Vol.2018 No.12