강판의 분무냉각 열전달특성

김영찬 安東大學校 工業技術硏究所 1999 공업기술연구논문집 Vol.6 No.1

분무냉각은 주로 강재의 열처리과정에 많이 이용되고 있다. 그러나 TMCP에 의한 강재냉각시 냉각영역의 출구에 있어서 강재의 온도가 불균일하게 되는 냉각불안정현상이 큰 문제점으로 남아 있다. 이러한 문제점의 해결에는 우선 강판의 열처리과정에 있어서 분무냉각 열전달특성에 대한 명확한 이해와 그 평가법의 개발이 중요하다고 할 수 있다. 본 연구에서는 주로 냉각액체의 포화온도이상의 물체를 냉각시키는 경우에 있어서의 분무냉각 열전달특성에 대해 최근의 연구결과들을 중심으로 고찰하기로 한다. Spray Cooling has been used as a technique for heat treatment of metals in the metallurgical industry. However, since there are many factors affecting spray cooling heat transfer and the effects of these factors are very complicated, it is still a difficult task to predict spray cooling heat transfer of actual system. Understanding the effect of these factors has become very important because of the advent of the so-called Thermo-Mechanical Control(TMC) process in the steel industry and other new applications. The aim of TMC process is on-line control of the metallurgical structure of steel. This paper presents an overview of the spray cooling heat transfer and the results of recent study on spray cooling.

학동기 비만아동의 피부두께의 통계적 관찰

김경석,나기찬,정은경,문경래,박상기,박영봉 朝鮮大學校 附設 醫學硏究所 1993 The Medical Journal of Chosun University Vol.18 No.1

The measurements of triceps skinfold thickness, body weight and height were done in children aged 7 to 12 years(3,142 boys and 2588 girls) in Kwangju in 1992. The author also observed degree of obesity, prevalence of obesity and average value of triceps skinfold thickness. The results were summarized as follows: 1) The mean value of triceps skinfold thickness acceding to age in male was 7 years 10.5mm, 8 years 10.5mm, 9 years 10.2mm, 10 years 12.3mm, 11 years 13.8mm, 12 years 12.3mm. In the female it was 7 years 11.9mm, 8 years 11.9mm, 9 years 11.6mm, 10 years 12.6mm, 11 years 14.1mm, 12 years 13.6mm. 2) The mean value of triceps skinfold thickness acceding to age in obese male was 7 years 16.3mm, 8 years 17.3mm, 9 years 16.0mm, 10 years 19.5mm, 11 years 23.7mm, 12 years 20.1mm. In the obese female it was 7 years 17.3mm, 8 years 17.9mm, 9 years 18.4mm, 10 years 19.5mm, 11 years 21.2mm, 12 years 20.3mm.

액막류의 막비등 열전달에 관한 연구

김영찬 安東大學校 工業技術硏究所 2000 공업기술연구논문집 Vol.7 No.1

강재의 냉각시 발생하는 액막류의 막비등 열전달 현상을 이해하기 위한 기초적 연구로서, 액상층의 두께가 비교적 얇고 난류상태인 액막류를 대상으로 한 막비등 열전달에 관해 실험적으로 검토하였다. 그 결과, 액막류의 막비등 열전달률에 대한 전열면 선단에서부터의 거리, 과열도 및 액막두께의 영향은 비교적 약하며, 막비등 열전달률에 영향을 미치는 주요인자는 액막류의 과냉도, 속도 등임을 알 수 있었다. 또한 액막류의 막비등 열전달률은 수정 Nussult 수를 이용함으로써 단상류의 난류 막비등 열전달과 유사한 형태의 정리식으로 나타낼 수 있었으며, 이러한 결과는 비교적 과냉도가 높은 액막류의 막비등 열전달은 거의 액체의 온도상승에 소비되어지고 있음을 나타내고 있다. In this report, subcooled film boiling heat transfer of liquid film flow formed by liquid spray on hot surface was simulated by film-boiling heat transfer of a subcooled liquid film flow supplied from a nozzle along the hot surface. Experimental data indicate that the effects of film thickness, wall superheat and distance from the leading edge on the film-boiling heat transfer were weak. The main parameters controlling the film-boiling heat transfer were liquid velocity and subcooling. The heat transfer correlation between the Nusselt number based on the modified heat transfer coefficient and the Reynolds number was obtained. The correlating equation was very similar to that of turbulent heat transfer of single phase flow, and it was found that most of the heat flux was dissipated to increase the liquid temperature.

히트파이프·휜으로 구성된 방열 시스템의 초음파 분무냉각에 관한 실험적 연구

김영찬,한양호 국립7개대학공동논문집간행위원회 2003 공업기술연구 Vol.3 No.-

In this study, the spray cooling heat transfer of the finned heat pipe heat sink was experimentally investigated. The heat pipe was made of copper tube 300mm long, 11.1mm inner diameter and the wick structure consists of two layer of 100 mesh copper screen. The evaporator and condenser lengths of heat pipe were 40, 200 mm and a series of copper fins attached to the condenser. The experimental results show that the heat transfer in the finned heat pipe heat sink is enhanced by using the ultrasonic spray cooling and the total thermal resistance of the heat sink system decreases remarkably.

액막류와 간섭하는 분무냉각 열전달

김영찬 安東大學校 工業技術硏究所 2001 공업기술연구논문집 Vol.8 No.1

본 연구에서는 막비등영역을 대상으로 2차원 분무류와 액막류가 간섭하는 경우의 분무냉각 열전달 실험을 수행하였으며, 특히 액막류의 속도, 분무유량 등이 분무냉각 열전달에 미치는 영향을 실험적으로 검토하였다. 그 결과, 분무류와 액막류가 간섭하는 경우 분무중심영역에서의 분무냉각 열전달은 액막류가 존재함으로써 저하하는 경향이 그 경향은 액막류의 두께가 증가할수록 크게 나타나고 있음을 알 수 있었다. 또한 분무중심에서 멀리 떨어진 주변영역에서의 분무냉각 열전달에 대한 분무액적유량의 영향은 그리 크지 않으며, 이 영역에서의 열전달은 기존의 액막류의 막비등 열전달에 관한 연구결과를 이용하여 예측될 수 있는 것으로 나타났다. In this paper, the heat transfer distribution in film-boiling region of spray cooling interacting with subcooled liquid film flow was experimentally investigated. The results show that the flow field can be divide into the interacting and film flow regions by heat transfer distribution. The interacting region is localized near the stagnation point of the spray flow. In this region, the existence of the liquid film flow deteriorates the spray cooling heat transfer. However, if we focus on flow boiling heat transfer, the droplet flow enhances flow boiling heat transfer. In the film flow region which is located far from the stagnation point of spray flow, the heat transfer coefficient is simply predicted from a correlating equation of flow boiling heat transfer.

초음파 분무냉각을 이용한 열사이폰의 작동특성에 관한 실헙적 연구

김영찬,한양호 국립7개대학공동논문집간행위원회 2002 공업기술연구 Vol.2 No.-

In this study, the working characteristics of the two-phase closed thermosyphon with ultrasonic spray cooling system in condenser section was experimentally investigated. The thermosyphon test tube was made of copper tube 300㎜ long, 11.1㎜ inner diameter. The experimental results were compared with the results that air cooling system were used in condenser section. The experimental results show that the total thermal resistance of thermosyphon tube becomes lower when the ultrasonic spray cooling system was used in condenser section. A comparison is made of the two working fluid, water and ethanol. The surface temperature of the water tube in evaporator section becomes higher than the ethanol tube. Thus, the experimental result shows that wate is more useful as working fluid than ethanol to increase the operational limit within this experimental conditions.

새마을 運動 實績評價模型 作成에 관한 硏究

黃明燦,玄斗日,梁始浩,朴英熙,金龍國,申大淳 건국대학교 1974 學術誌 Vol.17 No.1

The New Village (Sae-ma-eul) movement is Korean version of Community Development that has under-gone widespread exploration, experimentation and application in developing countries throughout the world in recent years. In most countries the national governments have undertaken the iniative in Community Development through appropriate ministries or special agencies. The New Village Movement was initiated in 1970 by Korean government. But it became a people's movement for self-development as more and more people participated in the developmental programs. The major objectives of the New Village movement are to redress the economic disparities between the rural and urban areas by improving the economic, social and cultural conditions of rural Communities, to reform the way of life in rural villages by encouraging the attitude of self-help, and to increase the income of the farmers and fisher man. Since 1971, An enormous amount of public and priate money has been invested into the New Village Movement. It seems that the time has arrived when some framework for evaluating the whole program is to be developed. Thus, The objective of this study is to develop an appropriate to evaluate the new village project at the village level. Ten major factors which are supposed to be relevant for evaluation of the project was selected. The evaluation model thus developed can be summarized in the following format. ◁표 삽입▷ (원문을 참조하세요)

Propylene Glycol Alginate 제조에 관한 연구

오찬열,김영조,강동섭,강영주,이장순 제주대학교 해양연구소 1988 해양자원연구소연구보고 Vol.12 No.-

A 12 Weeks, Randomized, Double-Blind, Placebo-Controlled Human Trial to Evaluate the Efficacy and Safety of Angelica gigas N. Extract Powder (Nutragen) on Joint Health

Yeung-Mi Kim,Ki-Chan Ha,Hyang-Im Beck,Hye-Mi Kim,Yu-Kyung Park,Min-Seok Han,Jong-Cheon Joo 한국식품영양과학회 2019 한국식품영양과학회 학술대회발표집 Vol.2019 No.10

A new 2-pyrone derivative, 5-bromo-3-(3-hydroxyprop-1-ynyl)-2H-pyran-2-one, suppresses stemness in glioma stem-like cells.

Kim, Rae-Kwon,Kim, Min-Jung,Yoon, Chang-Hwan,Lim, Eun-Jung,Yoo, Ki-Chun,Lee, Ga-Haeng,Kim, Young-Heon,Kim, Hyeonmi,Jin, Yeung Bae,Lee, Yoon-Jin,Cho, Cheon-Gyu,Oh, Yeong Seok,Gye, Myung Chan,Suh, Yongj American Society for Pharmacology and Experimental 2012 Molecular pharmacology Vol.82 No.3

<P>Glioma cells with stem cell properties, termed glioma stem-like cells (GSCs), have been linked to tumor formation, maintenance, and progression and are responsible for the failure of chemotherapy and radiotherapy. Because conventional glioma treatments often fail to eliminate GSCs completely, residual surviving GSCs are able to repopulate the tumor. Compounds that target GSCs might be helpful in overcoming resistance to anticancer treatments in human brain tumors. In this study, we showed that 5-bromo-3-(3-hydroxyprop-1-ynyl)-2H-pyran-2-one (BHP), a new 2-pyrone derivative, suppressed the maintenance of the GSC population in both a glioma cell line and patient-derived glioma cells. Treatment of GSCs with BHP effectively inhibited sphere formation and suppressed the CD133(+) cell population. Treatment with BHP also suppressed expression of the stemness-regulating transcription factors Sox2, Notch2, and β-catenin in sphere-cultured glioma cells. Treatment of GSCs with BHP significantly suppressed two fundamental characteristics of cancer stem cells: self-renewal and tumorigenicity. BHP treatment dramatically inhibited clone-forming ability at the single-cell level and suppressed in vivo tumor formation. BHP markedly inhibited both phosphoinositide 3-kinase/Akt and Ras/Raf-1/extracellular signal-regulated kinase signaling, which suggests that one or both of these pathways are involved in BHP-induced suppression of GSCs. In addition, treatment with BHP effectively sensitized GSCs to chemotherapy and radiotherapy. Taken together, these results indicate that BHP targets GSCs and enhances their sensitivity to anticancer treatments and suggest that BHP treatment may be useful for treating brain tumors by eliminating GSCs.</P>