• 한국산학기술학회논문지
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• 제19권2호
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• pp.683-688
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• 2018

본 논문에서는 탄소섬유를 이용한 면상발열체의 발열 상태를 영상처리 기술을 이용한 분석을 제안하였다. 면상발열체의 제작 방법은 탄소섬유를 작게 잘라 촙 상태로 만든 다음 분산제를 통하여 다시 결합시켜 준다. 그 다음 부직포 위에 분산제를 통해 결합된 탄소섬유 용액을 필터링 한다. 마지막 단계는 필터링된 탄소섬유를 건조 하면 부직포 형태의 면상 탄소 섬유를 얻을 수 있다. 면상발열체는 이렇게 제작된 면상 탄소 섬유에 전기를 인가하면 된다. 본 논문에서는 면상발열체를 4가지 방법으로 분석하였다. 분석 방법 중 면상 발열체의 발열특성 분석과 면상발열체의 발열속도 분석은 제작된 면상발열체가 정상군에 해당하는지를 확인한다. 절연 코팅 및 면상 발열체 모듈 분석은 실제 제품의 제작에 사용될 수 있는 면상발열체에 대해 영상처리 기술을 이용하여 2차원 이미지 분석이다. 면상발열체의 열화상 이미지 분석은 2차원 및 3차원으로 발열 상태를 분석할 뿐만 아니라, 발열의 상위온도 15~20%와 하위온도 15~20%를 이미지에 표시하는 프로그램 기법이다. 마지막 분석은 제작된 면상발열체의 상태를 화면에 직접 보여줌으로써 제작 과정 중 잘못된 부분을 쉽게 찾을 수 있다. 이와 같은 면상발열체의 이미지 분석 방법은 기존의 방법과 결합하여 발열상태를 더욱 정밀하게 분석할 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제31권7호
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• pp.833-841
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• 2007

The aim of this paper is to analyze the conjugate problems of heat conduction in solid walls coupled with laminar free convection flow adjacent to a vertical flat plate under boundary layer approximation. Using the similarity transformations the governing boundary layer equations for momentum and energy are reduced to a system of partial differential equations and then solved numerically using Finite Difference Method(FDM) known as the Keller-box scheme. Computed solutions to the governing equations are obtained for a wide range of non-dimensional parameters that are present in this problem, namely the coupling parameter P. the Prandtl number Pr and the heat generation parameter Q. The variations of the local heat transfer rate as well as the interface temperature and the friction along the plate and typical velocity and temperature profiles in the boundary layer are shown graphically. Numerical solutions have been consider for the Prandtl number Pr=0.70

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1153-1158
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• 2009

The performance of louver-finned flat-tube and fin & tube radiators for computer CPU liquid cooling were experimentally investigated. In this study, 7 samples of radiators with different shape and pass number (1, 2, 10) were tested in a wind tunnel. The experiments were conducted under the different air velocity range from 1 to 4 m/s. The water flow rate through a pass was 1.2 LPM. Inlet temperatures of air and water were $20^{\circ}C$ and $30^{\circ}C$ respectively. It was found that the best performance was observed in the louver-finned flat-tube sample considering pressure drop and heat transfer coefficient.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.258-263
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• 2007

The performance of louver-finned flat-tube radiators for computer CPU liquid cooling were experimentally investigated. In this study, 5 samples of louver-finned flat-tube radiators with different width size (19mm, 24mm), tube hole (1, 9) and pass number (1, 2, 5) were tested in a wind tunnel. The experiments were conducted under the different air velocity ranging from 1 to 5 m/s. The water flow rate through a pass was 1.7 LPM. Inlet temperatures of air and water were $20^{\circ}C$ and $30^{\circ}C$ respectively. The results showed that the best performance in the 24mm sample considering pressure drop and heat transfer coefficient.

• Journal of Biosystems Engineering
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• 제20권3호
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• pp.217-225
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• 1995

This study was conducted to find design factors of spraying device of the boom sprayer for low volume application. Four types of nozzles(standard flat nozzle, drift guard nozzle, even flat nozzle, and hollow cone nozzle) were used for the spray characteristic experiment. Spray patterns of the nozzles were distinguished by the nozzle type, spray distance, and spray direction. The flow rate was proportional to the square root of spray pressure in all nozzles. Increased nozzle height improved spray distribution at reduced pressures and/or increased spacing. Distribution tended to improve as pressure increased within the range of pressures used for fan nozzles.

• KSTLE International Journal
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• 제1권2호
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• pp.95-100
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• 2000

The thermal behaviors of disk-pad braking models has been analyzed for a high-speed train brake system using the coupled thermal-mechanical analysis technique. The temperature distribution, thermal distortion, and contact stress in the disk-pads contact model have been investigated as functions of the convective heat transfer rate. The FEM results indicate that multiple spot type pads show more stabilized thermal characteristics compared with those of the flat type pads for the increased convective heat transfer rate. The maximum contact stress for a friction pad loaded against a rubbing disk was occurred on the edge of the pad at the disk-pad interface.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.272-277
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• 2000

The heat transfer characteristics of confined turbulent slot jet impingement on the flat plate with square rods(turbulence promoter) have been experimentally investigated at different nozzle configuration. The effects of jet Reynolds number (Re=3900, 5800, 7800, 9700), dimensionless slot-to-plate distance(H/B=4, 6, 8) and clearance(c) between square rods and the plate were examined. Measurement of heat transfer rate were conducted using naphthalene sublimation technique. When square rods were inserted over the heat transfer surface, heat transfer rate was slightly increased in the wall jet region and the sharp-edged orifice nozzle was heigher than squared orifice nozzle.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.119-124
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• 2000

The heat transfer characteristics of confined turbulent slot jet impingement on the flat plate with square rods(turbulence promoter) have been experimentally investigated. The effects of jet Reynolds number (Re=3900, 5800, 7800, 9700), dimensionless slot-to-plate distance(H/B=4, 6, 8) clearance(c) between square rods and the plate, and the length(d) of a side of the square rod were examined. Measurement or heat transfer rate were conducted using naphthalene sublimation technique. When square rods were inserted over the heat transfer surface, heat transfer rate was slightly increased in the wall jet region.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2001년도 춘계학술대회 발표논문집
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• pp.290-291
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• 2001

The relationship between velocity, viscosity, diffusion coefficient, mass transfer coefficient and characteristic length and mass transfer data can be correlated by dimensionless relationship in electrolytic process. The performance of dyestuff removal was decreased as the flow rate of electrolyte was increased. It was due to the effect of retention time decreasing was superior to that of turbulent inlet mixing. Sh/Sc$\^$1/3/ vs Re plot for Al flat electrode did not showed the general tendency of the relationship between Sh/Sc$\^$1/3/ and Re. It can be thought that flow rate was not sufficiently high to increase the effect of mixing.

• 설비공학논문집
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• 제17권12호
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• pp.1177-1184
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• 2005

A numerical analysis was carried out on the heat and mass transfer, and pressure drop characteristics of the modular tube bundle heat exchanger. The finite volume method with a $k-\varepsilon$ turbulence model was used for the analysis. Due to condensation, the total heat transfer rate is observed about $4\~8\%$ higher than that on dry surfaces. Total heat transfer rate increases with increase in the velocity, temperature and relative humidity of incoming air. It also increases with decreasing the aspect ratio of heat exchanger tube. The inlet velocity of cooling water has little effect on the total heat transfer when the other conditions are fixed.