• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.96-101
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• 2001

Heat transfer in linear motor driven stages for surface mounting device applications was investigated. A simple one-dimensional thermal resistance model was introduced. In order to reduce three-dimensional nature to one-dimensional, a few assumptions and simplifications were employed suitably. A good agreement with a finite element heat transfer analysis in temperature profile was obtained. For validation, the analysis was compared with the measurement with respect to motor driving power. Overall discrepancy was less than $7^{\circ}C$. The influence of two high thermal resistance parts, insulation sheet and thermal contact between the coil assembly and the mounting plate, was examined through the analysis. Additionally, the thermal resistance analysis was applied to another stage including an internal cooling-air passage, and was found available for this system as well. After validation, the cooling effect was surveyed in terms of motor power, and cooling-air flow rate.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2002년도 춘계학술대회
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• pp.221-225
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• 2002

Machinability improvement by the use of liquid nitrogen in cryogenic machining has been reported in various studies. This has been mostly attributed to the cooling effect of liquid nitrogen. However, No study has been found in discussion on whether liquid nitrogen possesses lubrication effect in cryogenic cutting. This paper presents lubrication mechanism related to chip microstructure. The friction reduction was further reflected In larger shear angle and less secondary deformation in the chip microstructures.

• Tribology and Lubricants
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• 제5권1호
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• pp.44-50
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• 1989

High strength steel is similar to carbon steel in its composition. This material is developed originally for special uses such as aerospace and automobile due to its high strength and shock-free property in spite of lightness. But the chemical attraction of high strength steel is serious, which includes comminution of formation, metalization and strengthening. Machining results in built-up edge between this material and the tool. Especially the work hardening behavior results in tool life shortening, which was caused by temperature generation during machining. In this study, cooling system was made in which liquid nitrogen is supplied to circulate in order to make up for these weaknesses. Machining of high strength steels, which is recognized as difficult to machine materials, was conducted after tool is cooled at -195$\circ$C. Experimental results showed that the tool was cooled down rapidly below -195$\circ$C in about 200 seconds. The tool temperature of machining with cooling system was lowered by 60~95$\circ$C than that of machining in room temperature. The hardness of the surface of chip is decreased by machining with cooling system. And the machining using the cooling system made it possible to increase shear angle, to retain smooth surface on chip without built-up-edge and to get a better roughness.

• 한국기계가공학회지
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• 제16권3호
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• pp.16-23
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• 2017

For most machine tools, it is necessary to remove chips and coolant oil because it they will continue to be created during the manufacture of workpieces. Existing products that are in use are installed and used as they reflect depending on the characteristics of each device separately. This study proposes a method to remove the security chip as well as developing an integrated system capable of reducing coolant damage. The Leverage AutoCAD and CATIA program was used for 2D and 3D design, shapes were identified by utilizing the KeyShot program, and the load and displacement analysis of the development apparatus was performed utilizing the ANSYS program. After the prototype underwent sufficient design review, the mixed oil separation device had a complete sensor control program using the LabVIEW program. The chip design process for transferring experiments and experiments on the mixed oil cooling device were developed for performance tests of the product. The final product resulted in an increase in space utilization during commercialization, reduced installation costs, and caused social effects such as pulmonary flow reduction, which, through the economic costs, reduces pollution, resulting in various benefits to the industry, such as deceased errors in the workplace decreases.

• 대한기계학회논문집B
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• 제21권3호
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• pp.405-413
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• 1997

A thermal optimization of the chip arrangement in the PCB channel oriented vertically and cooled by natural convection has been studied. The objective of this study is to find the chip arrangement that minimizes the maximum temperature of the entire PCB channel. SIMPLER algorithm is employed in the analysis, and the genetic algorithm is used for the optimization. The results show that the chip with a maximum volumetric heat generation rate has to be located at the bottom of the channel, and chips with relatively high heat generation rates should not be close to each other, and small chip should not be located between the large chips.

• 한국초전도ㆍ저온공학회논문지
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• 제19권4호
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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.

• Journal of Advanced Marine Engineering and Technology
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• 제28권1호
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• pp.46-55
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• 2004

Thermal characteristics of the various cooling methods in electronic equipment are studied numerically. A common chip cooling system is modeled as a parallel channel with protruding heat sources. A two-dimensional model has been developed for the numerical analysis of compressible. viscous. laminar flow. and conjugate heat transfer between parallel plates with uniform block heat sources. The finite volume method is used to solve this problem. The assembly consists of two channels formed by two covers and one printed circuit board that is assumed to have three uniform heat source blocks. Various cooling methods are considered to find out the efficient cooling method in a given geometry and heat sources. The velocity and the temperature fields. the local temperature distribution along the surface of blocks. and the maximum temperature in each block are obtained. The results are compared to examine the thermal characteristics of the different cooling methods both quantitatively and qualitatively.

• 마이크로전자및패키징학회지
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• 제22권2호
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• pp.27-31
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• 2015

고성능 소자의 전력밀도가 증가함에 따라 소자의 열 관리는 주요 핵심 기술로 부각되었고, 기존의 heat sink나 TIM(thermal interface material)으로는 소자의 열 문제를 해결하는데 한계가 있다. 이에 최근에는 열 유속(heat flux)을 증가시키고자 액체 냉각 시스템에 관한 연구가 활발히 진행되고 있으며, 본 연구에서는 TSV(through Si via)와 microchannel을 이용하여 칩 레벨 액체 냉각 시스템을 제작하고 시스템의 냉각 특성을 분석하였다. TSV와 microchannel은 Si 웨이퍼에 DRIE(deep reactive ion etching)을 이용하여 공정하였고, 3가지 다른 형상의 TSV를 제작하여 TSV 형상이 냉각 효율에 미치는 영향을 분석하였다. TSV와 microchannel 내 액체흐름 형상은 형광현미경으로 관찰하였고, 액체 냉각에 대한 효율은 실온에서 $300^{\circ}C$까지 시편을 가열하면서 적외선현미경을 이용하여 온도를 측정 분석하였다.

• 조명전기설비학회논문지
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• 제25권12호
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• pp.34-41
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• 2011

In order to understand the thermal performance of each LED chips in multi-chip LED package, a quantitative parametric analysis of the temperature evolution was investigated by thermal transient analysis. TSP (Temperature Sensitive Parameter) value was measured and the junction temperature was predicted. Thermal resistance between the p-n junction and the ambient was obtained from the structure function with the junction temperature evolution during the cooling period of LED. The results showed that, the thermal resistance of the each LED chips in 4 chip-LED package was higher than that of single chip- LED package.

• 수산해양교육연구
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• 제16권2호
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• pp.210-217
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• 2004

Cooling technology has been a vital prerequisite for the rapid, if not explosive, growth of the electronic equipment industry. This has been especially true during the last 20 years with the advent of intergrated circuit chips and their applications in computers and related electronic products. The purpose of this study is to develop a telecommunication equipment cooling system using a thermoelectric module combined with cooling fan. Thermoelectric module is a device that can perform cooling only by input of electric power. In the present study, the cooling package using the thermoeletric module has been developed to improve the thermal performance. The cooling characteristics of the electronic chip was placed into the subrack and it can be rapidly assembled or disassembled in the equipment rack. As a preliminary experiment, the cooling performances between a conventional way using a cooling fin and a proposed method applying the thermoelectric module was comosed and analyzyed. The cooling performance at a simulated electronic component packaging a thermomodule operated well.