Development of a Microelectronic Cooling Device using a Micro Capillary Pumped Loop

JaeYong Lee,ChongBo Kim,Hayong Yun,KyungIl Cho,HyeJung Cho,InSeob Song 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.3

A capillary pumped loop (CPL), which is a microfabricated capillary pressure driven heat exchange cycle, is proposed as an alternative means of microelectronics cooling. In order to investigate the behavior of the Micro-CPL system, a lumped parameter model has been newly developed. The system simulation has been conducted for the capillary evaporator, condenser and two connecting valves. Specifically, a prototype micro-CPL with 20 W/㎠ cooling capacity has been modeled and tested. From the result, the prototype has been operated successfully under the heat flux with the heat junction temperature below 100℃. Also the system simulation model has well captured the overall trend of the experimental test data. Finally, the feasibility of Micro-CPL for high power chip cooling and the usefulness of the cycle simulation model for system design have been shown from this study.

Effects of Sampling Techniques and Sites on Rumen Microbiome and Fermentation Parameters in Hanwoo Steers

( Jaeyong Song ),( Hyuck Choi ),( Jin Young Jeong ),( Seul Lee ),( Hyun Jung Lee ),( Youlchang Baek ),( Sang Yun Ji ),( Minseok Kim ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.10

We evaluated the influence of sampling technique (cannulation vs. stomach tube) and site (dorsal sac vs. ventral sac) on the rumen microbiome and fermentation parameters in Hanwoo steers. Rumen samples were collected from three cannulated Hanwoo steers via both a stomach tube and cannulation, and 16S rRNA gene amplicons were sequenced on the MiSeq platform to investigate the rumen microbiome composition among samples obtained via 1) the stomach tube, 2) dorsal sac via rumen cannulation, and 3) ventral sac via rumen cannulation. A total of 722,001 high-quality 16S rRNA gene sequences were obtained from the three groups and subjected to phylogenetic analysis. There was no significant difference in the composition of the major taxa or alpha diversity among the three groups (p> 0.05). Bacteroidetes and Firmicutes represented the first and second most dominant phyla, respectively, and their abundances did not differ among the three groups (p> 0.05). Beta diversity principal coordinate analysis also did not separate the rumen microbiome based on the three sample groups. Moreover, there was no effect of sampling site or method on fermentation parameters, including pH and volatile fatty acids (p > 0.05). Overall, this study demonstrates that the rumen microbiome and fermentation parameters are not affected by different sampling techniques and sampling sites. Therefore, a stomach tube can be a feasible alternative method to collect representative rumen samples rather than the standard and more invasive method of rumen cannulation in Hanwoo steers.

Power Plant Pump Process Model Error Minimization Technique for Improving Simulator Fidelity

SooYong Yun,Kwan-Woong Gwak,Seung-Hyun Byun,Deockho Kim,Jaeyong Cho,Man-su Shin,ChangHyun Kim 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10

The power plant simulator is used to simulate the actual operation of a power plant, and for training and control verification. The simulator is built with the design data during the plant construction. The fidelity is low in the initial stage of operation because power plant modifications, deterioration, and logic corrections are not sufficiently reflected in a timely manner. To solve this problem, we propose a model error minimization technique for a pump process, one of the fundamental elements of the plant process, to improve fidelity. Model accuracy is improved by adjusting the parameters of the pump rated speed and characteristic curve based on the actual operating data. Performance is verified using actual operation data of the boiler feedwater pump in the circulating fluidized bed power plant.

해외 자회사의 현지임원비율 영향요인에 대한 다수준 연구 - 본사 역량의 조절효과를 중심으로

송재용(Jaeyong Song),윤채린(Chaerin Yun) 한국인사조직학회 2007 인사조직연구 Vol.15 No.2

  본 연구는 해외 자회사의 경험적인 역량과 본사 글로벌 역량이 자회사의 현지임원비율에 미치는 효과를 검증하는데 그 목적이 있다. 해외 자회사의 생존, 성과달성과 관련된 많은 선행 연구들은 본사와 자회사 간 관계를 강조하였으나, 본사와 자회사의 특성을 개별적으로 고찰하였을 뿐 그들 사이에 존재하는 관계의 역동성을 탐색하는 데는 소홀하였다. 102개의 일본 다국적 기업 본사와 이들이 보유한 307개의 해외 자회사를 대상으로 위계적 선형모형(HLM)을 사용한 본 연구의 실증 분석 결과 해외 자회사가 체득한 현지 시장에서의 경험적인 역량은 현지 임원비율을 높이는데 기여하는 반면, 본사가 지닌 기술적인 역량은 개별 자회사가 추구하는 임원진의 현지화에 제약을 가할 수 있음이 입증되었다. 또한 본사의 국제화 역량은 자회사의 현지임원비율에 직접적인 영향은 미치지 않았으나, 자회사의 현지 경험적 역량이 현지화 수준에 기여하는 영향력을 약화시키는 부(-)적인 조절변수의 역할을 수행할 수 있음이 추가적으로 밝혀졌다. 해외 자회사의 현지화와 관련하여 본 연구의 분석결과가 주는 시사점과 한계점은 결론 부분에서 논의하였다.   In the global expansion process, multinational corporations (MNCs)’ global strategy should address the tension between global integration and local responsiveness. In order to balance such conflicting priorities, one of the key strategic decisions that MNCs face is to determine the level of localization (e.g., level of hiring and empowering local managers, level of sourcing local components and technologies) in a specific host location where it set up an overseas subsidiary (Doz et al., 1981). Localization of a MNC is defined as a process of becoming a local firm by pursuing major value activities based on locally secured resources such as personnel, capital, raw materials and components, and technologies. Studies on the stages of the internationalization process also stress the importance of localization in the evolution of MNCs in host locations (Johanson & Vahlne, 1977). The experiential learning perspective views sequential foreign direct investments in a location as an evolutionary process of building firm-specific, local-bound capabilities in the location (Song, 2002). However, in spite of both academic and practical importance of localization in formulating international strategy of MNCs, the paucity of data prevented scholars from conducting a systematic empirical study of factors influencing the level of subsidiaries’ localization in a host location. This study aims at advancing our understanding about the determinants of localization by investigating factors that influenced localization decisions of Japanese electronics companies.<BR>  Today, there is widespread agreement that MNCs should be conceptualized as a differentiated network of internationally dispersed units. Overseas subsidiaries have to deal with not only differentiated local environments but also different requests and needs from coprorate headquarters, which they draw upon for resources and administrative practices. Thus, Overseas subsidiaries confront conflicting pressures for conformity to conditions in local environments in the host countries and for an imperative for consistency within the multinational enterprise. MNCs are inherently hierarchical. Subsidiaries are nested in both headquarters and local environments. Subsidiaries form part of an MNC that has the capacity to share knowledge across its various units (Bartlett & Ghoshal, 1998). And subsidiaries often embody social, professional, and technological relationships among local firms permitting inter-firm knowledge flows within their host countries (Almeida & Phene, 2004). Given this hierarchical characteristics, a natural concern is how different levels in the hierarchical system influence behaviors of overseas subsidiaries. Researchers in strategy and organization theory have long acknowledged the influence of a firm’s context on its behavior and performance.<BR>  Due to the inherently hierarchical nature of organizations, data collected in organizations consist of nested entities. Although most organizational researchers have chosen to investigate these multilevel models using traditional ordinary least squares approaches, hierarchical linear models have recently drawn growing attention (Hoffman & Gavin, 1998). Given the nature of organizations, it is clear that variables at one hierarchical level can influence variables at another level. Hierarchical linear models (HLM) provide a conceptual and statistical mechanism for investigating and drawing conclusions regarding the influence of phenomena at different levels of analysis (Hofmann, 1997). Thus, HLM can overcome the disadvantages of the traditional approaches. One of the primary advantages of hierarchical linear models is that they allow one to simultaneously investigate relationships within a particular hierarchical level as well as relationships across hierarchical levels. In order to model both within level and between-level relationships, one needs to simultaneously estima

Defects controlled stress engineering in Al-doped ZnO transparent multilayered thin films

Kang Jihye,Yun Jaeyong,Oh Yoo-Young,Kim Sung-Jin,Kamiko Masao,Kim Nam-Hoon,Koh Jung-Hyuk 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.5

This study explores stress engineering in multilayered structures of Al-doped ZnO thin films by controlling defects in them. Al-doped ZnO thin films are examples of transparent conducting oxides. Owing to their high conductivity and transparency, Al-doped ZnO thin films have various promising applications. However, defects and dislocations in thin films can deteriorate their electrical and optical properties. These defects or dislocations can be formed during the thin-film deposition process. Especially, defects can be formed between the layers during the stacking process of the sol–gel method. Therefore, methods to control defects have been designed and simulated to engineer stress in thin films. In this study, layered Al-doped ZnO thin films with different thicknesses were prepared to investigate the interface effects and electron motion in them.

기후변화가 하천의 유량에 미치는 영향 평가

박영윤(Young-yun Park),양주석(Joo-Seok Yang),김정직(Jeong Jik Kim),이재용(Jaeyong Lee) 대한지질학회 2015 대한지질학회 학술대회 Vol.2015 No.10

폐기물의 산소소모량 측정을 통한 매립지의 안정화상태 평가

윤수경 ( Suekyoung Yun ),박혜옥 ( Hyeok Park ),장재용 ( Jaeyong Jang ),박정현 ( Junghyun Park ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2019 No.-

국내에서 가장 큰 규모의 수도권매립지는 수도권지역 발생폐기물을 매립하는 광역매립지로 그중 제1매립장은 1992년 2월부터 생활폐기물 및 사업장폐기물을 매립하기 시작하여 2000년 10월 매립을 종료하고 현재는 관련법에 따라 사후관리 중에 있다. 제1매립장은 폐기물관리법 시행규칙 개정 전의 기준을 적용받아 사후관리기간이 20년임에 따라, 법적 사후관리 종료시기가 1년 앞으로 다가왔다. 이에 현재 매립장의 사후관리종료 판단 기준으로 사용되는 ‘사용종료 매립지 정비 및 사후관리 업무지침’ (환경부)의 기준과 제1매립장의 침출수 및 지하수, 매립가스, 매립폐기물 상태 등을 비교, 검토하여 매립지 안정화 수준을 파악할 필요가 있다. 특히 상시모니터링, 관리되고 있는 침출수, 매립가스 등과 달리 매립폐기물에 대한 안정화 여부는 이전까지 평가된 바 없으므로 매립된 폐기물을 굴착하여 생분해도 정도를 평가할 필요가 있었다. 한편 AT4는 호기적 조건에서 4일 동안 폐기물 분해에 따라 생산되는 이산화탄소의 압력변화를 토대로 산소소모량을 산출하는 방법으로, 실험소요 기간이 짧고 그 방법이 간단하여 폐기물의 생분해도 및 안정화를 평가하는 효과적인 방법 중 하나로 알려져 있다. 이에 본 연구는 제1매립장내 8개 지점을 선정하여, 매립된 폐기물을 깊이별로 굴착하고 해당 폐기물의 특성 분석 및 Oxitop을 이용한 AT4 실험을 실시하여, 매립폐기물의 안정화 정도를 확인하고 ‘사용종료 매립지 정비 및 사후관리 업무지침’에 제시된 매립폐기물 생분해도 평가기준과 비교하였다. 그리고 매립기간에 따른 폐기물 상태변화를 비교하기 위하여 2018년 매립 종료된 제2매립장내 일부 지점의 폐기물을 굴착하여 동일한 실험을 실시하여 그 결과를 비교·평가하였다.

자율주행시대 도로 인프라 변화 방향 조사

윤재용(YOON, Jaeyong),김보성(KIM, Bo Sung),윤덕근(YUN, Dukgeun) 대한교통학회 2022 교통 기술과 정책 Vol.19 No.4

저온 저장고에서 냉기 보조 덕트를 활용한 온도 균일도와 에너지 효율성 향상에 관한 연구

윤현(Hyeon Yun),김준현(Joon Hyun Kim),성재용(Jaeyong Sung) 대한기계학회 2020 大韓機械學會論文集B Vol.44 No.5

본 연구에서는 농산물 저장용 저온 저장고의 실내기 토출구에 냉기 보조 덕트를 설치하여 저장고내 온도 균일도와 에너지 효율성 향상에 대해 고찰하였다. 실제 저온 저장고의 냉각 운전에 대한 실증실험 데이터를 기반으로 비정상 3차원 유동에 대한 수치 해석을 수행하였으며, 덕트의 설치 유무와 다공성 덕트 슬릿의 공극률에 따른 저장고 내 온도 및 기류 분포를 비교하였다. 그 결과, 냉기 보조 덕트의 공극률이 낮을수록 냉각 운전 전후 열평형에 의한 적정 온도 대역에 놓이는 공간 영역이 높았다. 또한 덕트의 존재는 기류의 거동에 있어서 효율적인 순환 효과로 저장고 내부 온도 분포의 균일도가 향상시켰고 냉각 에너지 소비량을 줄였다. In this study, the improvement of temperature uniformity and energy efficiency was investigated by installing auxiliary ducts connected to a unit cooler in a low-temperature warehouse for long-term cold storage of cabbage. Based on the empirical data for the refrigeration system of a real storage, numerical simulations were conducted for the 3D unsteady flows inside the storage. Then, the distributions of temperature and velocity fields were compared according to the presence of the duct and the porosity of the duct slit. The results show that at the lower the porosity of the duct slit, the larger the space in the warehouse that remains in the proper temperature band owing to the heat balance during one cooling operation cycle. The auxiliary duct leads to the effective circulation of cooling flows; hence, the temperature uniformity improves and the consumption of cooling energy decreases when the duct is installed.

기계적 체결부를 포함한 복합재 압력용기의 구조해석

윤재호(Jaeho Yun),장명욱(Myungwook Jang),강해성(Haesung Kang),김재용(Jaeyong Kim),손현일(Hyunil Shon) 한국추진공학회 2017 한국추진공학회 학술대회논문집 Vol.2017 No.11