• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2000년도 KIASC Conference 2000 / 2000년도 학술대회 논문집
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• pp.136-138
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• 2000

1.5kA HTS current leads for a superconducting magnetic energy storage(SMES) magnet, which are connected to a conventional vapor cooled copper leads, were designed. The HTS lead composed of cylindrically arranged Bi-2223/Ag-1 at5Au tapes and a stainless steel tube. The minimum operating current of the lead is 1.71 kA at 77.3K, self magnetic field, and the heat input to the liquid helium from the clod end of the 36 cm lead is 0.5 W/lead.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.7-12
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• 2000

The purpose of this study is to develop heat transfer analysis program of heat pipe elements and design a revolving heat pipe exchanger by the performance experiment of hot air production by means of middle-temperature waste heat. Experimental variables are the revolution per minute, normal velocity of inlet air and the temperature of waste heat. The revolving heat exchanger has designed as $2^{\circ}$ in inclination angle of heat pipe bundle and as 20% in working fluid quantity and as water in working fluid. Experimental value of the total heat transfer coefficient was $20w/m^2-^{\circ}C$

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.341-346
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• 2000

This experimental study investigated the flow motion of the working fluid for various diameters of miniature thermosyphons and the performance characteristics for the various amount of the working fluid. The temperatures of condenser surface were measured and visual observations were conducted. The test results show that some fluid condensed in the tube diameters of 0.18cm and 0.22cm is not returned to the evaporator section due to capillary effect so that large temperature gradients are measured. To enhance returning the working fluid, one copper wire of 0.5mm diameter was inserted and the test results show good performance. When the liquid charge was less than 10% in volume dry-out was occurred fur the thermosyphons of the inner diameter of 1.8mm and 2.2mm.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.204-208
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• 1995

Copper magnetron anode of a microwave-oven consists of an cylindrical outer-tube and various inner-vanes. The magnetron anode is produced by the complex process ; vane blanking, pipe cutting and sliver-alloy brazing of vanes. Recently, the backward extrusion process for forming vanes has been developed to avoid the complex procedures. The developed process is analyzed by using upper-bound elemental technique(UBET). In the UBET analysis, the upper-bound load, the configuration and the vane-height of final extruded product are determined by minimizing the total power consumption with respect to chosen parameters. To verify theoretical analysis, experiments have been carried out with pure plasticine billets at room temperature, using different web-thickness and number of vanes. The theoretical predictions both for forming load and vane-height are in reasonable agreement with the experimental results.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1991년도 춘계학술대회 논문집
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• pp.251-255
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• 1991

The primary objectives of the rolling process are to reduce the cross section of the incoming material while improving its properties and to obtain the desired section at the exit from the rolls. Many engineering metals, suchas aluminium alloys, copper alloys, and steels are often cast intoingots and are then further processed byhot rolling into blooms, slabs, and billets, which are subsequently rolled into other products such as plate, sheet, tube, rod, bar, and structural shapes. In shape rolling a round or square bar is rolled in several passes into various shapes. During eachpass, the bar elongates as well as spreads. Thus, a very complex three-dimensional metal flow takes place. In this paper TASKS results for the simulation of a 7 pass square-to-round shape rolling are presented. The results are verified by comparing it with experimental results from a previous study conducted at the Battelle Columbus Labs

• Environmental Engineering Research
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• 제7권4호
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• pp.227-237
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• 2002

Chemical vapor deposition (CVD), ion beam sputtering (IBS) and sol-gel method were used to prepare TiO$_2$ thin films for degradation of hazardous organic compounds exemplified by 2-chlorophenol (2-CP). The influence of supporting materials and coating methods on the photocatalytic activity of the TiO$_2$ thin films were also studied. TiO$_2$ thin films were coated onto various supporting materials including steel cloth (SS), copper cloth, quartz glass tube (QGT), and silica gel (SG). Results indicate that SS (37 μm)- TiO$_2$ thin film prepared by IBS method improves the photodegradation of 2-CP. Among all supporting materials studied, SS(37 μm) is found to be the best support.

• International Journal of Air-Conditioning and Refrigeration
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• 제14권4호
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• pp.125-130
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• 2006

This study has been performed to investigate the thermal performance of variable conductance heat pipe (VCHP) with screen meshed wick. The active length of condenser section in a VCHP is varied by non-condensible gas, which controls the operating temperature, and the heat capacity of VCHP is controlled by the operating temperature. In this study, numerical analysis of the VCHP based on the diffusion model of non-condensible gas is done for the thermal control performance of VCHP. Water is used as a working fluid and nitrogen as a control non-condensible gas in the copper tube. As a result, the thermal conductance of VCHP has been compared with that of constant conductance heat pipe (CCHP) corresponding to the variation of operating temperature.

• 설비공학논문집
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• 제13권6호
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• pp.440-447
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• 2001

This study investigate experimentally the effect of in height, thickness, and clearance on the boiling heat transfer. The heat surfaces having copper fin array is tested for pool boiling. The gas-liquid exchange interference is investigated based on fin array clearance. These test results can be applied to the design of tube bundle system. The fin height of 2 mm is found to be effective. Effects of heat transfer promotion reaches the highest level when the fin clearance is 0.5mm. Also, heat flux is increased when the fin thickness is smaller. But0.2 mm fin thickness is highly recommended.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.73-76
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• 1999

We have fabricated and tested a Bi-based high temperature superconducting current lead system. Ag sheathed Bi-2223 mono-filament tapes of $I_c=8.4$ A at 77 K under self-field condition were fabricated using powder-in-tube(P1T) method. Multi-layer current leads can be made by stacking of Ag sheathed Bi-2223 mono-filament wires. The critical current of this 10-layer current lead is about 68 A. The contact resistance across the copper-current lead interface has been studied using current-voltage characteristics. At temperature below critical temperature the resistive contribution of the interface to the total contact resistance dominates. We have measured AC transport losses in a current lead at 77 K, 60 Hz by a transport method.