• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.107-108
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• 2007

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2003년도 하계학술대회 논문집
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• pp.40-40
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• 2003

• 대한기계학회논문집B
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• 제28권3호
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• pp.304-314
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• 2004

An experimental study has been conducted to measure the temperature fields and the local film cooling effectiveness for two and three staggered rows of the rectangular shaped-holes with various blowing rates. The hydraulic diameter of rectangular-shaped hole is 10mm. To compare with the film cooling performance of rectangular-shaped hole, two kinds of circular holes are tested. One has the same hydraulic diameter as the rectangular hole and the other has the same cross sectional area. Also, rectangular holes with expanded exit with same inlet area as rectangular ones are tested. Temperature fields are measured using a thermocouple rake attached on three-axis traversing system. Adiabatic film cooling effectiveness on the surface are obtained based on experimental results of thermochromic liquid crystals. The film cooling effectiveness is measured for various blowing rates and compared with the results for the cylindrical holes. In case of 2 rows, the rectangular holes has better performance than circular holes due to its slot-like geometry. In case of 3 rows, the effecta of hole shape is not clear.

• Journal of Advanced Marine Engineering and Technology
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• 제36권1호
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• pp.64-71
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• 2012

An efficient cooling system is an essential part of the electronic packaging such as a high-luminance LED lighting. A special technology, Pulsating Heat Pipe (PHP), can be applied to improve cooling of a sealed, explosion-proof LED light fixture. In this paper, the characteristics of the pulsating heat pipes in the imposed thermal boundary conditions of LED lightings were experimentally investigated and a PHP device that works free of alignment angle was investigated for cooling of explosion-proof LED lights. Five working fluids of ethanol, FC-72, R-123, water, and acetone were chosen for comparison. The experimental pulsating heat pipe was made of copper tubes of internal diameter of 2.1 mm, 26 turns. A variable heat source of electric heater and an array of cooling fins were attached to the pulsating heat pipe. For the alignment of the heating part at bottom, an optimum charging ratio (liquid fluid volume to total volume) was about 50% for most of the fluids and water showed the highest heat transfer performance. For the alignment of the heating part on top, however, only R-123 worked in an un-looped construction. This unique advantage of R-123 is attributed to its high vapor pressure gradient. Applying these findings, a cooling device for an explosion-proof type of LED light rated 30 W was constructed and tested successfully.

• 열처리공학회지
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• 제35권6호
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• pp.319-326
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• 2022

Direct extrusions of an aluminum 7075 alloy were carried out using 1500 ton machine with and without die cooling system. Cooling of extrusion die has been performed by the flow of liquid nitrogen and controlled by laser thermometer. Billet was 180 mm in diameter and 500 mm in length. The preheating temperatures of billet, container and die were 390℃, 400℃ and 450℃, respectively. Ram speed was kept with 1.25 mm/sec first. The change of ram speed was carried out during extrusion according to the observation of surface defects such as crack or tearing. Extrudates of 8.3 m in length, 100 mm in width and 15 mm in thickness were obtained to observe and analyze surface defects by optical microscopy and EBSD (Electron BackScattered Diffraction). In case of extrusion without die cooling cracks on the surface and tearing in the corner of extrudate occurred in the middle stage and developed in size and frequency during the late stage of extrusion. At the extrusion with die cooling the occurrence of defects could be suppressed on the most part of extrudate. EBSD micrographs showed that cracks and tearings have been resulted from the same origin. Surface defects were generated at the boundaries of grains formed by secondary recrystallization due to surface overheating during extrusion.

• 대한기계학회논문집B
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• 제28권5호
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• pp.594-603
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• 2004

Several desiccant cooling systems have been developed in terms of cost and performance. In this study a fin-tube exchanger has been used for liquid desiccant dehumidification system. This dehumidifier has been designed to study the absorption characteristic of the aqueous triethylene glycol(TEG) solution which has the flow range from 20 to 50 LPM. The dehumidifier performance characteristics of working factor variables such as inlet solution flow rate, air flow rate, solution concentration and brine temperature have been analyzed. This dehumidifier has the ability to provide running while saving the latent heat load of total energy. The result of this experiment can provide useful data for hybrid air conditioning system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.25-30
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• 2003

Several desiccant cooling systems have been developed in terms of cost and performance. In this study a fin-tube exchanger has been used for liquid desiccant dehumidification system. This dehumidifier has been designed to study the absorption characteristic of the aqueous triethylene glycol(TEG) solution which has the flow range from 20 to 50 LPM. The dehumidifier performance characteristic of working factor variables such as inlet solution flow rate, air flow rate, solution concentration, solution temperature, brine temperature, air temperature and inlet air relative humidity has been analyzed. The result of this experiment can provide useful data for hybrid air conditioning system.

• 한국광학회:학술대회논문집
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• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.201-205
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• 1989

In this study, the vertical type LPE system has been developed by fully hand-made. The temperature fluctuation and minimum cooling rate of this LPE system are within $\pm$0.05$^{\circ}C$ and 0.15$^{\circ}C$/min, respectively. It is considered that these properties are enough to grow III-V semiconductor compounds single crystals by liquid phase epitaxy method. Futhermore in this study. 1.3${\mu}{\textrm}{m}$ GaInAsP/InP single crystal growing has been carried out by this system. It has been obtained that the growing rate was about 0.72${\mu}{\textrm}{m}$/min for InP binary layer and 0.36${\mu}{\textrm}{m}$/min for GaInAsP quarternary layer under 0.6$^{\circ}C$/min cooling rate condition.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 하계학술발표대회 논문집
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• pp.221-221
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• 2007

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.241-244
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• 2006

The analysis of propellant feeding sub-system is performed using a commercial code SINDA/FLUINT, the comprehensive finite-difference, one-dimensional, lumped parameter tool. With the code, cryogenic helium supply system, liquid oxygen supply system, helium injection cooling system are evaluated. The code gave satisfactory estimation scheme for propulsion system characterized by cryogenic temperature and high pressure, two phase flow. This paper focuses on presenting calculation scheme of propulsion sub-system using one-dimensional code like SINDA/FLUINT.