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동력분산형 고속 철도차량 추진제어 장치용 수냉각 장치의 최적설계에 관한 연구 ; 냉각판
김철주(Kim Chul-Ju),유성열(Ryoo Seong-Ryoul),조태식(Jo Tae-Sik) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.11월
The HEMU-400X is a new national model of an ultra high speed electric commuter tat is currently under development. An unit of its propulsion system consists of 4 inverters and 3 converters to provide about 410㎾ power to the motor. And this unit is in need of cooling to keep the enclosed power semi-conductors within their allowed temperature limits at around 100 ℃, and the estimated cooling loads are about 40kW. From the paper studies on cooling units, it was known that most countries including Europe and Japan adopt water cooling systems to evacuate heat from their propulsion units, and we have the same kinds of interest on these cooling problems. In general, a water cooling system consists of the two essential parts, one is a cooling plate on the surface of which IGBTs are to be attached and the other is a radiator with a matrix of a flat tube-louver fins heat exchanger which is to radiate the heat to the environment air flow. The present study is focused on the procedures of design to optimize the cooling plate and the most of the results were based on the analysis of flows of working fluid and heat.
Formocresol의 농도 변화에 따른 치수조직의 반응에 대한 연구
한국재,조태식 朝鮮大學校 口腔生物學硏究所 1997 口腔生物學硏究 Vol.21 No.2
The purpose of this study was to evaluate pulp tissue reactions to various concentrations of formocresol (full concentration, 1/5, 1/25, 1/125 diluted concentrations of Buckley's formoresol). Young adult mongrel dongs, again 1 year, weighting 10㎏ or more, were used in this investigation. Pulpotomies with various concentrations of formocresol were performed on dog's teeth. Intervals from pulpotomy to sacrifice were 1, 2, 5, and 10weeks, All specimens containing pulpotomized teeth were fixed in 10% neutral formalin solution, decalcifide in Plank Richlo solution, embedded in praffin and sectioned 6-8μm in thickness. All sectioned tissues were stained with hematoxylin-eosin stain mothod. The following results were obtained through microscopical examination. 1. The pulp tissue reaction to 1/5 dilution group of formocresol were similar to that of full concentration group. 2. The full concentration and 1/5 dilution groups of formocresol were effective, but 1/25 and 1/125 dilution groups of formocresol were not effective in fixing the pulp tissue. 3. The 1/25 and 1/125 dilution groups of formocresol produced severs inflammatory reaction in the pulp tissue, and formed suppuration with increased experimental time. 4. All specimens showed progression of inflammatory and degenerative changes toward apical region with increased experimental time.