• Journal of the Korean Solar Energy Society
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• v.23 no.2
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• pp.91-98
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• 2003

Experimental study for a porous aluminum heat dissipator/or heat sink made by casting method is conducted to evaluate the performance of the porous aluminum heat sinks. The parameters applied for the present study are the manufacturing method. various bonding materials for the bottom plate of heat sink, and their different material, pore size, etc.. The casting method for porous aluminum heat sink is suggested for the best performance of heat dissipation in this experiment. The bottom plate applied by melting aluminum is introduced and proved their excellent characteristics compared with brazing, soldering, and bonding methods. In the present experiment, aluminum with different conductivities, such as AC8A and pure aluminum, are tested and the pure aluminums with the higher conductivity than AC8A shows their improvement of the performance. And the proper dimensions related to the pore size and the height of porous aluminum heat sinks are proposed in the present study.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.587-592
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• 2009

Heat transfer model and energy dissipation rate were investigated to examine the heat transfer mechanism in bubble columns with continuous operation. The energy dissipation rate($E_D$) obtained from the unsteady state heat transfer model based on the surface renewal theory was significantly small, comparing with the hydrodynamic energy dissipation rate($P_v$) calculated from the overall hydrodynamic energy balance based on the behaviors and holdups of gas and liquid phases in the column. It was found from these results that the energy dissipation rate based on the surface renewal theory is independent of the hydrodynamic energy dissipation rate obtained from the overall hydrodynamic energy balance in the bubble column, in considering their mechanism. The different two energy dissipation rates were correlated in terms of operating variables within this experimental conditions, respectively.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.11
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• pp.3072-3083
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• 1995

The numerical simulation on the three-dimensional natural convection heat transfer in the enclosure with heat generating chip is performed, and the effects of convective heat loss and vents are also examined. The effects of the Rayleigh number and outer Nusselt number (Nu$_{0}$) on the maximum chip temperature and the fractions of heat loss from the hot surfaces are investigated. The results show that conduction through the substrate is dominant in heat dissipation. With the increase of Rayleigh number, heat dissipation through the chip surfaces increases and heat loss through the substrate decreases. Maximum dimensionless temperature with vents is found to decrease about 40% compared to the one without vents at Nu$_{0}$=0.l. It is also shown that effects of size and location of the vents are negligible.ble.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.4
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• pp.371-377
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• 2017

In this study, the heat dissipation performances of metal printed circuit boards (MPCBs) and flexible printed circuit boards (FPCBs) used in light-emitting diode (LED) lights were compared and analyzed by performing a heat dissipation simulation using a thermal flow analysis program. The results were summarized graphically. The temperature distribution of the MPCB was found to be better than that of the FPCB, indicating the better heat dissipation performance of the MPCB. For the two FPCB structures studied, we confirmed the LED temperature and temperature distribution by thermal flow analysis and found that for better overall heat dissipation performance, PCBs should preferably have an asymmetric structure. We confirmed the possibility of using FPCBs, which are characterized by a flexible structure, for LED lighting.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.6
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• pp.439-444
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• 2020

An increase in the temperature of photovoltaic (PV) modules causes reduced power output and shorter lifetime. Because of these characteristics, demands for the heat dissipation of PV modules are increasing. In this study, we attached a heat dissipation sheet to the back sheet of a shingled PV module and observed the temperature changes. The PV shingled module was tested under Standard Test Conditions (STCs; irradiance: 1,000 W/㎡, temperature: 25℃, air mass: 1.5) using a solar radiation tester, wherein the temperature of the PV module was measured by irradiating light for a certain duration. As a result, the temperature of the PV module with the heat dissipation sheet decreased by 3℃ compared to that without a heat dissipation sheet. This indicated that the power loss was caused by a temperature increase of the PV module. In addition, it was confirmed that the primary parameter contributing to the reduced PV module output power was the open circuit voltage (Voc).

• Design & Manufacturing
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• v.13 no.3
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• pp.24-28
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• 2019

In this study, a study was carried out that could effectively produce a heat dissipation effect on plastic materials. Using carbon nanotube (CNT), aluminum powder and plastic, the material properties were tested in 2 cases of compounding ratio. The test sample mold was designed and constructed prior to the experiment. The experiments include tensile strength, elongation rate, flexural strength, flexural elasticity rate, eye-jaw impact strength, gravity and thermal conductivity. Results from 60% and 70% mixture of aluminium to plastic were tested, and a 10% less combined result was a relatively good property. For research purposes, the heat dissipation effect and light weighting obtained a good measure when the combined amount of Al was 60%.

• Design & Manufacturing
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• v.13 no.3
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• pp.6-10
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• 2019

In this study, a study was carried out that could effectively produce a heat dissipation effect on plastic materials. Using carbon nanotube (CNT), aluminum powder and plastic, the material properties were tested in 2 cases of compounding ratio. The test sample mold was designed and constructed prior to the experiment. The experiments include tensile strength, elongation rate, flexural strength, flexural elasticity rate, eye-jaw impact strength, gravity and thermal conductivity. Results from 60% and 70% mixture of aluminium to plastic were tested, and a 10% less combined result was a relatively good property. For research purposes, the heat dissipation effect and light weighting obtained a good measure when the combined amount of Al was 60%.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.63-69
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• 2022

Compressor efficiency must be improved to reduce refrigerator power consumption. In this study, the heat dissipation rate through the compressor housing is increased via gap flow passages between the compressor body and housing. Four types of gap flow passages are considered for achieving the maximum heat-dissipation rate. In addition, thermal analysis is performed to examine the effect of increased heat dissipation rate on the energy efficiency ratio (EER). The results show that the heat dissipation rate, compressor superheat, and compressor EER increased by up to approximately 52%, 3 ℃, and approximately 1%, respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.5
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• pp.96-102
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• 2019

This study investigated the heat dissipation characteristics of a heat-sensitive LED. More than 80% of the power supply is converted into heat energy, which has a fatal impact on the lifetime of the LED. Therefore, the effective heat dissipation characteristics of a heatsink, such as a 30W floodlight, through forced convection were grasped and the heat transfer characteristics were tested. As a result, it was confirmed that the smaller the number of fins, the more the temperature distribution varies according to the wind velocity. In addition, the larger the number of fins, the smaller the temperature difference according to the wind velocity. Therefore, it was found through this experiment that excellent heat dissipation performance was exhibited as the heat dissipation area and wind velocity increased.

• Progress in Superconductivity and Cryogenics
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• v.19 no.4
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• pp.18-21
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• 2017

We report a method for improving heat exchange between cryo-cooled large-power-dissipation devices and liquid cryogen. Micro-machined monolithic heat sinks were fabricated on a high integration density superconducting Josephson device, and studied for their effect on cooling the device. The monolithic heat sink showed a significant enhancement of cooling capability, which markedly improved the device operation under large dc- and microwave power dissipation. The detailed mechanism of the enhancement still needs further modeling and experiments in order to optimize the design of the heat sink.