• Journal of the Korean Society for Precision Engineering
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• v.24 no.12
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• pp.95-103
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• 2007

This paper presents a liquid cooling concept for heat rejection of high power electronic devices existing in notebook computers etc. The design, fabrication, and performance of the planar ECF pump and farced-liquid cooling system are summarized. The electro-conjugate fluid (ECF) is a kind of dielectric and functional fluids, which generates jet flows (ECF-jets) by applying static electric field through a pair of rod-like electrodes. The ECF-jet directly acts on the working fluid, so the proposed planar ECF pump needs no moving part, produces no vibration and noise. The planar ECF pump, consists of a pump housing and electrode substrate, achieves maximum flow rate and output pressure of $5.5\;cm^3/s$ and 7.2 kPa, respectively, at an applied voltage of 2.0 kV. The farced-liquid cooling system, constructed with the planar ECF pump, liquid-cooled heat sink and thermal test chip, removes input power up to 80 W keeping the chip surface temperature below $70\;^{\circ}C$. The experimental results demonstrate that the feasibility of forced-liquid cooling system using ECF is confirmed as an advanced cooling solution on the next-generation high power electronic devices.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.3
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• pp.237-242
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• 2012

Spaceborne pulse tube-type cryogenic compressors are widely used for space applications. To guarantee cooling performance of the compressor, mission life time and micor-vibration stability, suitable thermal control of compressor is required. Micro-vibration of the compressor is the one of the sources to degrade the pointing performance of observation satellite. In the present work, on-orbit thermal design of compressor in order not to degrade the performance of micro-vibration isolation system keeping the thermal control performance has been proposed and investigated through thermo-mechanical analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4072-4080
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• 2014

The Peltier Module has been used to dissipate the heat from electronic devices and electronic components. In this module, a heat sink is used to release the operating heat into the air outside. This study addressed the heat transfer characteristics for a heat sink with an inner tunnel. Under forced and natural convection conditions, the heat transfer characteristics were different. Therefore, the cooling and heating performances were studied for the heat sink, which has an inner tunnel. The heat transfer conditions were also evaluated by performing an experimental test, which investigated the heat transfer characteristics related to the variance in time and temperature distribution. Experiments on the heat transfer characteristics of the heat sink were conducted based on the forced and natural convection and temperature distribution changes. In the cooling experiment, the A- and B-shaped cooling pin heat sinks decreased the temperature of the forced convection than the temperature of natural convection. In the forced and natural convection, the A- and B-shaped decreased to a minimum of $-15^{\circ}C$. Under the forced and natural convection conditions, A- and B-shaped cooling pin heat sinks decreased the temperature when the voltage was increased. In the heating experiment, the A- and B-shaped cooling pin heat sinks increased the temperature of the forced convection than the temperature of natural convection. In forced convection, when the voltage was $15^{\circ}C$, the temperature of the A-shaped cooling pin heat sink increased to $150^{\circ}C$, and the temperature of the B-shaped cooling pin heat sink increased to $145^{\circ}C$. Under forced and natural convection conditions, the A- and B-shaped cooling pin heat sinks showed an increase in temperature with increasing voltage.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.2
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• pp.230-239
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• 1996

A multi-faceted experimental investigation has been carried out to study the cooling performance for stacked modules in arrays of heat generating rectangular modules deployed along PCB's in the enclosed cabinet. The main parameters which have an important effect on cooling characteristics are flow velocity, channel spacing, installation of fan unit, attachment of heat sink, and acoustic noise. The results of individual effect are very helpful for the electronic packaging designer. In order to improve the cooling performance, it is certain that the enlargement of channel space is obviously effective, while this id disadvantageous in high density electronic packaging. Each of the paameters is quantitatively examined as cooling performance and the correlation of Reynolds number to Nusselt number is compared with previous study.

• Proceedings of the Korean Society of Community Living Science Conference
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• 2003.11a
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• pp.152-152
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• 2003

본 연구의 목적은 고추 수확과 같은 여름철 농작업 시 농민의 온열 스트레스 경감을 위한 피복 장비 개발 연구의 일환으로 두 종류의 기능성 모자를 개발하고 그 성능을 비교 검토하는 것이다. 피험자로는 건강한 남자 대학생 열 두 명이 참가하였다. 인공기후실 실험 조건은 네 가지로 모자를 쓰지 않은 경우 (Control), 챙이 넓은 시판 농작업모를 착용한 경우 (Hat A), 반사 소재의 냉각 모자를 착용한 경우 (Hat B), 반사소재이면서 통기 구조를 갖는 냉각 모자를 착용한 경우 (Hat C)이다. 인공 기후실 내 환경 조건은 기온 33$\pm$0.5$^{\circ}C$, 습도 65$\pm$5%RH, 복사 온도 39$\pm$1$^{\circ}C$로 WBGT 33$^{\circ}C$를 유지하였고, 피험자들은 120분(50분 작업, 10분 휴식, 50분 작업, 10분 휴식) 동안 모델화된 고추 수확 작업을 수행하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.8
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• pp.973-982
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• 1997

Effect of vortex generator on the heat transfer enhancement of electronic chips is investigated using naphthalene sublimation technique. Experiments are performed for a single chip and chip arrays, and shape of vortex generator, position of vortex generator, stream wise chip spacing and air velocity are varied. Local and average heat transfer coefficients are measured on the top surface of simulated electronic chips, and compared with those obtained without vortex generator. In case of a single chip, heat transfer augmentation is seen only on the upstream portion of chip surface, while heat transfer enhancement is found on the whole surface for chip arrays. Rectangular wing type vortex generator is found to be more effective than delta wing.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.31-36
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• 2003

Recently, the power consumption and heat generation in an electronic equipment increase as the components are miniaturized and the computing speed becomes faster. Effective cooling method is required to ensure the guaranteed performance and reliable operation of the electronic devices. The aim of the present study is to investigate the cooling characteristics of a pin-fin heat exchanger as a candidate for cooling system of the electronic devices. 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 characteristics. The results are compared with the experimental data or correlations of several researchers for the channel flow with pin-fin arrays.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2003.12a
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• pp.35-41
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• 2003

반도체 제조라인의 유틸리티 분야에 국내 기술이 도입되고 이에 따른 관리시스템 구축의 중요성이 부각되고 있으며 유틸리티 시스템의 한 부분인 냉각 시스템의 효율성 증대에 관심을 보이고 있다. 본 연구에서 펌프의 효율 계산 프로그램을 NUMS(New Utility Management System)에 반영하고 현재 가동중인 시스템인 NUMS와 같은 조건 하에서 정상상태 유동해석을 통하여 각 구성 요소에서의 유량 및 압력을 제공할 수 있는 시스템을 구현 하였고 NUMS와 압력비교를 하였다. 또한 효율성 증대를 위해 적절한 By-pass 밸브의 개도와 펌프 1대를 줄일 수 있는 결과를 얻었다. 이 결과는 차후 운전 및 관리의 효율성 증대와 에너지 절감을 위한 자료로 이용하고자 한다.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.489-494
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• 2006

Electronic and telecommunication industries are constantly trying to develop compact components having high power density. Therefore, a proper heat dissipation method is very important to allow reliable operation of the telecommunication equipment. In this study, a hybrid refrigeration system for a telecommunication equipment room was designed to save energy consumption and improve reliability of the compressor In addition, the performance of the hybrid refrigeration system was measured with a variation of outdoor load. The designed hybrid refrigeration system for the telecommunication equipment shelter saved the energy approximately 50%e at the mode switch temperature of $8.3^{\circ}C$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.2
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• pp.266-275
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• 1995

A numerical investigation on the conduction-natural convection-surface radiation conjugate heat transfer in the enclosure having substrate and chips has been performed. A 2-dimensional simulation model is developed by considering heat transfer by conduction, convection and radiation. The solutions to the equation of radiative transfer are obtained by the discrete ordinates method using S-4 quadrature. The effects of Rayleigh number and the substrate-fluid thermal conductivity ratio on the cooling of chip are analyzed. The result shows that radiation is the dominant heat transfer mode in the enclosure.