• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.8
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• pp.821-828
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• 2012

Increasing heat generation in CPUs can hamper effective recirculation and by-pass because of the large temperature difference between the exhaust and the intake air through a server room. This increases the overall temperature inside a data center and decreases the efficiency of the data center's cooling system. The purpose of the data center's cooling system is to separate the intake and exhaust air by controlling the computer room air-conditioner(CRAC). In this study, ICEPAK is used to conduct a numerical analysis of a data center's cooling system. The temperature distribution and the entire room are analyzed for different volumetric flow rates. The optimized volumetric flow rate is found for each CPU power. The heat removal and temperature distribution for CPU powers of 100, 120, and 140 W are found to be the best for a volumetric flow rate of $0.15m^3/s$. The numerical analysis is verified through RTI indicators, and the results appear to be the most reliable when the RTI value is 81.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.961-966
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• 2001

Micro fans of randomly swept-blades were designed to provide C.P.U. in a personal computer with effective cooling in a very quiet mode. The proto--type axial micro-fans machined by a laser sintering machine were tested against manufactured products by comparing the performance and overall sound pressure level with spectral measurements in an environment suggested by ASHRAE and ANSI standards. The predicted OSPLs and directivity patterns of fans by iDesignFan software were in good agreements with measured data. The newly introduced fans of randomly swept-blades were proved to provide a very promising mode of low noise at small loading conditions.

• Journal of the Semiconductor & Display Technology
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• v.15 no.3
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• pp.12-17
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• 2016

In this study, numerical simulations for the conjugate heat transfer of air with a heat-sink of CPU were conducted. The heat-sink consisted of many fins of cylinder shape and the effect of the number of fins on the cooling performance of the heat sink was investigated. Grid independent solutions were obtained to compare the maximum temperature of the heat-sink for various conditions. It was found that maximum temperature of the heat-sink asymptotically approached 310K as the number of fins went to infinity. The energy exchange of air with the heat-sink was found to be nearly independent on the number of fins.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.77-82
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• 2000

Parametric study fur the cooling characteristic investigation of a notebook PC mounted with heat spreader has been numerically performed. Two oases of air-blowing and air-exhaust at inlet were tested. The cooling effect on Parameters such an, velocities of air-blowing and air-exhaust, materials of heat spreader, and CPU powers were simulated for two cases. Cooling performance in the case of air-blowing was better than the case of air-exhaust.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.725-728
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• 2002

A separate type thermosyphon can be utilized as a cooling device of electronic equipments (such as CPU of a personal computer or notebook). This study was carried out to investigate the cooling effect of separate type thermosyphon and to find the adequate parameters affecting the separate type thermosyphon. The heat transfer characteristics of separate type thermosyphon were obtained from experimental results. A $50{\times}50{\times}2 mm$ heat source was copied after CPU for the experiments. The results indicate that the device is capable of dissipating 60W of thermal energy and keeping the heat plate surface temperature under 50'E and the device can transfer heat from the evaporator to the condenser through natural circulation (without any external driving forces). Some transport phenomena of the working fluid and the heat transfer characteristics of the loop were observed in the experiments and are discussed in detail below.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.6
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• pp.799-803
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• 2001

Miniature heat pipe(MHP) with woven-wired wick was used to cool the CPU of a notebook PC. The pipe with circular cross-section was pressed and bent for packaging the MHP into a notebook PC with very limited compact packaging space. A cross-sectional area of the pipe is reduced about 30% as the MHP with 4mm diameter is pressed to 2mm thickness. In the present study a performance test has been performed in order to review varying of operating performance according to pressed thickness variation and heat dissipation capacity of MHP cooling module that is packaged on a notebook PC. New wick type was considered for overcoming low heat transfer limit when MHP is pressed to thin-plate. The limiting thickness or pressing is shown to be within the range of 2mm∼2.5mm through the performance test with varying the pressing thickness. When the wall thickness of 0.4mm is reduced to 0.25mm for minimizing conductive thermal resistance through the wall of heat pipe, heat transfer limit and thermal resistance of MHP were improved about 10%. In the meantime, it is shown that the thermal resistance and heat transfer limit for the MHP with central wick type are higher than those of MHP with existing wick types. The results of performance test for MHP cooling modules with woven-wired wick to cool a notebook PC shows the stability as cooling system since T(sub)j(Temperature of Processor Junction) satisfy a demand condition of 0∼100$\^{C}$ under 11.5W of CPU heat.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.205-209
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• 2000

The performances of cascade-type thermoelectric modules are analysed by numerical simulations. The geometrical variations are used as design parameters.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.10
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• pp.776-783
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• 2008

The object of this paper is to study on the thermal performance of a micro channel water block for computer CPU cooling. The effects of liquid flow rate, micro channel width and height on the thermal performances of water block are investigated experimentally. The water block was fabricated Al and machined with a micro milling. The water block consisted of rectangular micro channels 0.5 to 0.9 mm width and 1.5 to 4.5 mm height. The experiments were conducted using deionized water, over a liquid flow rate ranging from 0.2 to 2.0 kg/min. The base temperature and thermal resistance decrease with increasing of liquid flow rate. The increase of a channel height is more effective on the thermal resistance than the decrease of a channel width. At the flow rate of 0.7 kg/min, input power of 100 W, the base temperature and thermal resistance of sample 6 is $33^{\circ}C$ and $0.13\;^{\circ}C/W$ respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1475-1483
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• 2004

Loop thermosyphon(LTS) has many good characteristics such as low thermal resistance, no power consumption, noiseless operation and small size. To investigate the overall performance of LTS, we have performed various experiments varying three parameters: input power of the heater, working fluid(water, ethanol, FC3283) and filling ratio of the working fluid. At a combination of these parameters, temperature measurements are made at many locations of the LTS. The temperature difference between the evaporator and the condenser is used to obtain the thermal resistance. In addition, flow visualization using a high speed camera is carried out. The thermal resistance is not constant. It is lower at higher input power, which is one of the distinct merits of LTS. Flow instabilities are frequently observed when changing the working fluid, the input power and the filling ratio. The results show that the LTS can be readily put into practical use. Future practical application in electronic cooling is recommended.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.274-276
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• 2010

Three noise sources are come from note PC system; HDD, System Cooling Fan and ODD. Except HDD, user can accept as an acceptable operating noise. System Fan needs to cooling down the CPU and Chipset and ODD only works when it need to work, therefore user thinks these two noise sources are necessary. For the HDD, some times it makes noise without user HDD access action such as re-organizing cache and defragmentation, user can hardly accept this noise. At the circumstance like as library and the room at the dawn, user can recognize the noise easily so that makes dissatisfaction. I'm studying algorithm and method to reduce HDD noise for user satisfaction.