• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.6 s.237
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• pp.747-754
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• 2005

Because the liquid-vapor interfacial shear stress affects seriously the liquid flow and the maximum heat transport rate of the grooved wick heat pipe, an accurate modeling for the pressure drop characteristics of the liquid flow is required. A novel method for calculating the liquid pressure drop and the velocity profile of an open channel flow in a microchannel with an arbitrary cross-section is suggested and validated by experiments. An experimental apparatus for the Poiseuille number of the liquid flow in open rectangular microchannels with the hydraulic diameters of 0.40mm, 0.43mm, 0.48mm is used in order to reproduce real situations in the grooved wick heat pipe. Analytic results from the suggested method are compared with the experimental data and they are in a close agreement with each other.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.1
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• pp.70-76
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• 2004

High-temperature cylindrical sodium/stainless-steel heat pipes were manufactured and tested for transient as well as steady states. Total length of the heat pipe was 1 m and the diameter was 25.4 mm. Screen meshes of 3 different sizes were used to estimate the effect of mesh size on the thermal performance of the heat pipe. The minimum thermal resistance achieved was as low as 0.02$^{\circ}C$/W for the maximum thormal load of 2 ㎾. The average heat transfer coefficient in the evaporator was about 2,000 ㎾/$m^2$K and those in the condenser region were up to 5 times higher.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.1
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• pp.77-83
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• 2004

In this study, the spray cooling heat transfer and working characteristics of the screen wick heat pipe with ultrasonic spray cooling system in condenser were experimentally investigated. The heat pipe was made of copper tube 300 mm long with inner diameter of 11.1 mm. The evaporator and condenser lengths of heat pipe were 40, 200 mm and the wick structure consists of two layer of 100 mesh copper screen. The experimental results show that the ultrasonic spray cooling increases the heat transfer rate on the condenser surface, and the total thermal resistance of heat pipe system decreases remarkably. A comparison is made for the two working fluids, water and ethanol. The surface temperature of the ethanol tube in evaporator section becomes higher than that of the water tube. Thus, the experimental result shows that water is more useful than ethanol as the working fluid because of increasing the operational limit within this experimental conditions.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.7-12
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• 2003

heat pipe with screen meshed wick. The heat pipe was designed in 200 screen meshs, 500 mm length and 12mm O.D tube of copper, water as working fluid and nitrogen as non-condensible gas. Heat pipe used in this study has evaporator, condenser and adiabatic section, respectively. Experimental data of wall temperature distribution along axial length is presented for heat transport capacity, condensor cooling water temperature change, degrees of an inclination angle, and operating temperature.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.5
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• pp.779-786
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• 1986

Hot-wire anemometer with constant temperature hot-wire anemometer bridge, linearizer, D.C. stabilization electric power source and square-wave generater has been constructed for trial and the test has been carried out. As a result the test showed the overall frequency response of 6KHz over the change of air flow and the noise of approximately 1cm/s in an air flow of 10m/s. The accuracy of the lienarizer stands comparison with the existing anemometer and turned out to be relatively good operational characteristics.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1997.11a
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• pp.134-139
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• 1997

가상 현실 세계에서 정보교류의 수단으로 자신의 정보를 제공하거나 또다른 정보를 수집하는 등의 정보교류와 자신을 표현하고자 하는데에 기존의 2차원의 캐릭터보다는 3차원의 캐릭터를 이용하여 사용자의 대리인으로 분신(Avatar)을 사용하는 3차원 영상을 주제로 하는 많을 연구들이 진행되고 있다. 본 연구에서는 가상현실 세계에서의 분신이 좀 더 현실감이 있는 자연스러운 행동과 상호작용을 보이기 위해서 사람 모습을 닮은 분신을 연구하였으며, 실세계의 자연스러운 정보들(손 동작, 몸 동작)을 분신에 적용하여 가상세계에서 분신의 행동양식과 상호작용이 가능하고 시각, 청각, 역각등의 다중형태의 정보들을 3차원으로 제공하고자 하는데 중점을 두었다. 이 시스템은 가상세계에서 분신을 생성하며 몇가지의 기본 행동을 가지고 간단한 방법과 실시간으로 분신의 움직임을 처리 할 수 있는 분신의 행동양식과 상호작용이 가능한 하가지 시스템을 소개할 것이다. 또한 이 시스템은 다른 기종의 플랫폼(PC, W/S)간에 다중참여자를 위하여 네트윅 환경하에서 실행 될 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.370-372
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• 2005

RFID기술의 발전과 더불어 RFID 미들웨어 시스템의 중요성은 커지고 있으나 가용성 제공 수준은 아직 미흡하다. 현재 출시된 RFID 미들웨어 시스템은 가용성을 제공한다 하더라도 범위가 한정되거나 범용성이 없는 자사 기술 집약적인 형태를 보인다. 현 기술 현황으로는 다양한 도메인과 다양한 수준에서의 가용성을 보장하기란 한계가 있다. 본 논문에서는 가용성 관리를 위한 프레임웍을 제공함으로써 프레임윅을 기반으로 RFID 미들웨어 시스템의 가용성을 보장하는 방안을 제시한다. 가용성 관리 프레임웍은 가용성 보장을 위한 기본 로직을 프레임웍을 통해 제공하므로 RFID 미들웨어 시스템은 원하는 수준의 가용성을 보장 받을 수 있다. 가용성 관리 프레임웍을 통한 가용성 제공은 재사용성, 확장성, 유연성, 이식성의 장점을 지니며 가용성을 보장하는 RFID 미들웨어 시스템 구현에 대한 용이성을 제공할 것이다.

• Journal of ILASS-Korea
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• v.7 no.2
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• pp.31-36
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• 2002

According to the improvement of PC performance, it is expected that calorific value, which causes PC to malfunction, is increased. Therefore, the development of new cooling system is recently required. As the method to solve this problem, we applied loop heat pipe to PC cooling system. The advantage of the loop heat pipe is that it has a small size, light weight, simple shape, long life and it has a good performance on heat transfer, no-noise, wide range of applicable temperature and no supply of power from the outside. It is confirmed that loop heat pipe reduces thermal resistance and has a good performance on PC cooling.

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.63-63
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• 2003

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1225-1230
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• 2004

In this paper, the pressure drops were investigated according to the sintered porous wick structure in loop heat pipe(LHP) by theoretical analysis. LHP has the wick only in evaporator for the circulation of working fluid, so utilizes porous wick structure which pore diameter is very small for large capillary force. This paper investigates the effects of different parameters on the pressure drops of the LHP such as particle diameter of sintered porous wick, wick porosity, vapor line diameter, thickness of wick and heating capacity. Working fluid is water and the material of sintered porous wick is copper. According to the these different parameters, capillary pressure, pressure drop in wick were analized by theoretical design method of LHP.