• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.7 no.1
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• pp.20-25
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• 2014

There are several severe problems for LED device, the next generation's economy green lighting: as the temperature increases, the lamp efficiency decreases; if the temperature is over $80^{\circ}C$, the lifetime of lighting decreases; Red Shift phenomenon that wavelength of spectrum line moves toward long wavelength occurs; and optical power decreases as $T_j$ increases. Thus, Heat sink design that can minimize the heat of LED device is currently in progress. While the thermal resistance of COB Type LED was reduced by direct coupling of LED chip to the board, residential 13.5W requires Heat sink in order resolve heat issue. This study designed Heat Sink suitable for residential 13.5W COB LED down-light and selected the optimum Fin thickness through flow simulation that packaged the designed Heat Sink and 13.5W COB. And finally it analyzed and evaluated the thermal modes using contacting thermometer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1484-1488
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• 2009

This thesis is about Heat-sink design which is considered as the biggest problems for commercialization of LED lighting and suggests how to solve the problems though analysis on heat-sink using COMSOL. The temperature difference after simulation value and modelling was $10^{\circ}C$by Transient analysis of Heat Transfer Module which is in the COMSOL Multiphysics. The result approximated the object which is close to actual lighting, when various elements are used according to temperature change of interior and exterior surroundings LED lighting is set up.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.150-156
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• 2017

This study tests the characteristics of heat radiation by applying the pin-height variables to 30-W LED floodlights. The angle of the heat sink enables us to identify the characteristics of the heat radiation based on the temperature distribution. The results of the study are as follows. When the heat sinks are set towards the ground, the heat transfer decreases in speed only to expands the temperature distribution, which adversely affects the characteristics of heat radiation and expands the temperature distribution of PCB with the LED chip. We verify that the characteristics of heat radiation are adversely affected when the height of the cooling pin decreases and the heat radiation area decreases, which impedes the heat transfer and increases the temperature distribution on the heat sink.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4398-4404
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• 2012

This thesis was conducted a numerical analysis on the radiant heat performance according to factors of design of heat sink for cooling of the automotive LED head lamp. The heat sinks were designed with 5 different types to fit the limited internal space by formula based on an existing product (Type 1). Designed heat sinks of five types were analyzed by ANSYS CFD V12.1, and the analysis results were compared with the existing type. The results of simulation were analyzed temperature distribution and average temperature, air flow characteristic, heat flux etc. This thesis was researched on the correlation of the cooling performance according to the heat sink structure and the fin shape. Through numerical analysis, could be confirmed heat sink Type 2 as the best results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.9
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• pp.1263-1271
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• 2001

An experimental study is carried out for an aluminum foam heat sink attached to an isolated heat source to evaluate high potential of aluminum foam as a heat sink with impinging jets. The effects of the pore density and the height of the aluminum foam heat sink, the jet Reynolds number, and the nozzle diameter are delineated in comparison with a conventional pin type heat sink. It is found that the aluminum foam with small pores is inefficient for the heat transfer enhancement due to the large flow friction at the given porosity. In the parameter ranges of the present study, the change in the nozzle diameter shows no significant effects on the surface temperature of the aluminum foam heat sink at a given Reynolds number. The heat transfer enhancement is strongly dependent on the jet Reynolds number and shows a maximum value at a moderate Reynolds number.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.8
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• pp.544-549
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• 2015

Since LEDs (light emitting diodes) have many advantages as a light source in vehicle headlamp, such as good reliability, energy and space saving, and flexible headlamp design. On the other hand, the dependence of its performance and life on temperature have great influence on its practical use. In this study, design and fabrication of heat sink for vehicle LED headlamp were performed using thermally-conductive plastics. This study focused on the effective heat sink structure with limited space in the vehicle LED headlamp. We designed two different prototype of heat sink by thermal simulation using SolidWorks program, which had excellent temperature characteristics. The two different prototype of heat sink were fabricated by injection molding with thermally-conductive plastics. The results showed that LED $T_j$ (junction temperature) of sample B (model 1) and sample C (model 1, 2) was below then $165^{\circ}C$ when applying the thermally-conductive plastics in heat sink of vehicle LED headlamp.

• Journal of the Korean Society of Visualization
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• v.22 no.1
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• pp.79-84
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• 2024

As microchips' degree of integration is getting higher, its cooling problem becomes important more than ever. One of the promising methods is using fractal microchannel heat sink by mimicking nature's Murray networks. However, most of the related works have been progressed only by numerical analysis. Perhaps such lack of direct experimental studies is due to the technical difficulty of the temperature and heat flux measurement in complex geometric channels. Here, we demonstrate the direct visualization of in situ temperature profile in a fractal microchannel heat sink. By using the temperature-sensitive fluorescent dye and a transparent Polydimethylsiloxane window, we can map temperature profiles in silicon-based fractal heat sinks with various fractal scale factors (a=1.5-3.5). Then, heat transfer rates and pressure drops under a fixed flow rate were estimated to optimize hydrodynamic and thermal characteristics. Through this experiment, we found out that the optimal factor is a=1.75, given that the differences in heat transfer among the devices are marginal when compared to the variances in pumping power. This work is expected to contribute to the development of high-performance, high-efficiency thermal management systems required in various industrial fields.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.8 s.227
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• pp.961-967
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• 2004

An inclined jet impinging on a pin fin heat sink is proposed and investigated experimentally. To investigate the flow pattern, flow visualization using fluorescence and velocity measurement using particle image velocimetry(PIV) are conducted with water. The jet impinges over a wide span of the heat sink with a large recirculation in the upper free space and occasionally with another smaller one in the upstream corner. Further, thermal experimentation is conducted using air to obtain temperature profiles using a thermocouple rake in the air and using thermal image on the heat sink back plate, with impinging angles of 35, 45 and 55 degrees. The Reynolds number range based on the nozzle slot is varied from 1507 to 6405. The results show that impinging angle of 55 degree shows the largest heat transfer capability. The results of thermal experiment are compared and discussed with those of flow visualization.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3524-3528
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• 2007

In this study, the Peltier effect was applied to eliminate moistures in the air enclosed by a cabinet. We have developed the new electronic dehumidifier which has a new function of automatically evaporating the condensed water inner cabinet into the outside air. To obtain this function, the processes of dehumidification is that it condensed the moistures on the cold side heat sink and drained it into the hot side heat sink by the both gravitational and capillary forces and the droplets on the hot side heat sink surface was evaporated into the air outside the cabinet by the heat conducted through the hot side heat sink surface and the forced heat convection through the fan for cooling hot side heat sink. Compared to existing electronic dehumidifiers, this manufactured one showed a good performance that the electric power consumption for the same dehumidifying quantity was reduced by 50% compared with that of existing ones.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.3
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• pp.417-422
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• 2002

The experiments have been carried out to evaluate the cooling performance of a fan-aluminum foam heat sink assembly in comparison with a conventional CPU cooler. In terms of the dimensionless surface temperature of the heater, the cooling performance of the aluminum foam heat sink is similar to that of the conventional one with much reduced weight. The optimum fin height is found to be strongly dependent on the fin height of the heat sink and flow characteristics of the cooling fan.