• 한국분무공학회지
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• 제19권2호
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• pp.88-93
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• 2014

Nanofluids is that metallic or nonmetallic nanometer-sized particles are dispersed in liquid and they can be used in various fields to increase the heat transfer rate. This study conducted experiments to evaluate whether the cooling efficiency of nanofluids is better than that of water in spray cooling. A heated surface was designed and fabricated to make the temperature distribution be linear, which was confirmed by three thermocouple measurements under the heated surface. Spray cooling experiments were conducted using water, 0.2% wt. (weight), and 0.5% wt. $Al_2O_3$ nanofluids at the pressure of 0.2 MPa and 0.3 MPa. Based on the results, it is shown that the cooling efficiency of nanofluids is higher than that of water especially in the region of single phase heat transfer. As a result, we can expect that nanofluids can be used as efficient coolants in the cooling of electronic packages where the temperature of the heated surface is not high enough for boiling incipience.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2438-2443
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• 2007

In order to guarantee the performance of electronic products. It is needed to improve the cooling performance of heat sink. So this paper has been made to investigate the cooling performance for the aluminum heat sink using pulsating heat pipe(PHP). The pulsating heat pipe was used as a heat spreader. Working fluid was R-22. Heater (50 mm ${\times}$ 50 mm ${\times}$ 3mm) was attached to heat sink and it generated 30W, 60W, 80W, 100W. Heat sink was tested for forced convection with 1${\sim}$4m/s of inlet air velocity. And both type heat sinks were carried out by using CFD simulation. This study showed that pulsating heat pipe can be a good tool to improve cooling performance of heat sink.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.414-418
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• 2001

Flow and thermal characteristics of cooling system for the robot controller were numerically as well as experimentally investigated. To obtain the overall flows within controller, the system level solutions were analysed at first and then the board level solutions were pursued to understand the detailed flow and temperature fields near the main board which have a significant influence on the cooling of electronic components. The evaluation for a performance of the heat exchanger was conducted on the basis of the obtained flow and temperature patterns. The results showed that the heat exchanger made a small contribution to the cooling of controller and caused an increase of the temperature in CPU.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.195-200
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• 2009

The objectives of this study are to analyze of energy consumption and operation conditions of each cooling system for gas and electric driven systems, and to compare operating cost for five different cooling systems; ice storage system, system air-condition, turbo chiller as the electric driven cooling systems, and absorption chiller and Gas driven Heat Pump (GHP) as the gas driven cooling systems. The sample designs are carried out based on the types of business, capacity, installation region and year.

• 한국기계가공학회지
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• 제17권1호
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• pp.138-143
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• 2018

In general, the operating temperature of electronic equipment is closely related to product life and reliability, and it is recognized that effectively cooling the parts is an important problem. In this paper, an experimental study on the cooling characteristic according to the pin array of the heat sink is conducted. The experiment on the heat sink was based on the natural convection and temperature distribution changes. The experimental results indicate that the pin array of the heat sink has an effect on the thermoelectric module's cooling characteristic.

• ETRI Journal
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• 제20권4호
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• pp.380-394
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• 1998

A numerical study has been performed to predict the characteristics on the transient operation of the heat pipe with multiple heaters for electronic cooling. The model of the heat pipe was composed of the evaporator section with four heaters, insulated transport section, and the condensor section with a conductor which is cooled with uniform heat flux condition to surrounding. The governing equations and the boundary conditions were solved by the generalized PHOENICS computational code employing the finite volume method. Two test cases are investigated in present study; Case 1 indicates that the 1st and 2nd heaters among four heating sources are heated off, while the 3rd and 4th heaters are heated on. Case 2 is the inverse situation switched from heating location of Case 1. The results show that the transient time to reach the steady state is shorter for Case 1 than for Case 2. Especially, the temperature difference of the heater during switching operation is relatively small compared to the maximum allowable operating temperature difference in electronic system. Hence, it is predicted that the heat pipe in present study operates with thermally good reliability even for switching the heaters.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2137-2143
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• 2008

This paper investigates the plate loop heat pipe system with an evaporator mounted with fin-wick structure to dissipate effectively the heat generated by the electronic components. The heat transfer formulation is modeled and predicted through thermal resistance analysis of the fin-wick structure in the evaporator. The experimental approach measures the thermal resistances and the operating characteristics. These results gathered in this investigation have been used to the objective of the information to improve the LHP system design so as to apply as the future cooling devices of the electronic components.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.410-414
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• 2001

The microstructure, V-I characteristics, and stability of ZnO-Pr$_{6}$O$_{11}$-CoO-Cr$_2$O$_3$-Y$_2$O$_3$based vairstors were investigated with cooling rate in the range of 2~8$^{\circ}C$/min. The cooling rate relatively weakly affected the microstructure, and the varistor voltage and the leakage current in the V-I chracteristics. But the nonlinear exponent relatively strongly affected by cooling rate. And the cooling rate also greatly affected the stability for DC stress. In gross, the varistors cooled with 4$^{\circ}C$/min exhibited the highest performance in the densification, nonlinearity, and stability. Especially, they exhibited a high stability, in which the variation rate of the varistor voltage and the nonlinear exponent is -1.44% and -4.85%, respectively, under more severe DC stress such as (0.80 V$_{1mA}$9$0^{\circ}C$/12 h)+(0.85 V$_{1mA}$115$^{\circ}C$/12 h)\`(0.90 V$_{1mA}$12$0^{\circ}C$/12 h)+(0.95 V$_{1mA}$1$25^{\circ}C$/12 h)+(0.95 V$_{1mA}$15$0^{\circ}C$/12 h). It should be emphasized that the stability of these varistors is much superior to that of others.s.of others.s.

• 설비공학논문집
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• 제18권6호
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• pp.459-467
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• 2006

Rapid development of electronic technology requires small size, high density packaging and high power in the electronic devices, which results in more heat generation. Suitable heat dissipation is required to ensure the guaranteed performance and reliable operation of the current state-of-the-art electronic equipment. The aim of the present study is to find out the forced-convective thermal-hydraulic characteristics of a pin-fin heat exchanger as a candidate for cooling system of the electronic devices through the analysis and experiment. Various configuration of the pin-fin array is selected in order to find out the effect of spacing and diameter of the pin-fin on the heat transfer and pressure drop characteristics. Experimental results are compared with the analyses and correlations of several researchers. Finally, the design guide are provided for the required pressure drop and/or the heat transfer characteristics of the heat exchanger.

• 한국자동차공학회논문집
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• 제21권6호
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• pp.1-7
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• 2013

This paper focuses on cooling fan control by using a magnetic clutch type for the improvement of fuel economy on a heavy city bus. In general, Heavy duty vehicles use viscous clutch type cooling fan which has some disadvantages, such as slow response, wide temperature variation of engine coolant water. But a magnetic clutch type cooling fan can be controlled electronically so the engine coolant temperature can be precisely controllable and this effects could be used to reduce fuel consumption. A control system for applying the magnetic clutch type cooling fan was developed in this study and applied to the real field test and chassis dynamometer test. The result showed well controlled coolant temperature and enhancement of fuel economy.