• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.315-318
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• 2002

The use of high-temperature superconducting materials for transmission cable application is being realized in prototype situation. HTS cable systems have been installed in laboratories and tested successfully around the world. In korea. the first step in development of superconducting cables is distribution system. In this paper. it is proposed the HTS distribution system modeling using ATPDraw and EMTDC programs. In the multilayer conductor, the inner layers have higher impedance than the outer layers. As a result, the current concentrate$ in the outer layers. This paper presents the result of the current distribution in EMTDC.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.334-337
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• 1999

High T$_c$ (${\sim}$21,500 A/cm$^2$, at 77K) of 100m length of BSCCO 2223 tapes have been achieved using optimized precursor powders with carefully controlling variables in heat treatment. Prototype 500A class multistrand conductor for HTS power cable was fabricated using these tapes. Also discussed are the transportation properties of prototype 500A class multistrand conductor.

• Progress in Superconductivity
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• 제3권1호
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• pp.115-119
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• 2001

For the fabrication of HTS power cable, multifilamentary Bi-2223/Ag tapes have been prepared using the powder-in-tube (PIT) process. After final heat treatment, these tapes have $I_{c}$ value of 43A, and$ J_{c}$ value of $28,000A/\textrm{cm}^2$(77K, 0T). Prototype 1000A class multistrand conductor(length~1m) was fabricated using these tapes(length~300m). This multistrand conductor was impregnated with low-temperature epoxy. The transportation properties of prototype 1000A class multistrand conductor has been evaluated at 77K, and yielding a current capacity up to 1200A.A.A.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.958-960
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• 2002

High Temperature Superconducting (HTS) devices make it possible to operate with no electrical loss by resistance. If, however, the applied current is over its critical current, the phase of HTS devices is changed to normal state, so called, quench. In this case, since resistance of HTS is increased abruptly, it can not be avoidable to damage the whole apparatus. In this study, quench detector to protect HTS devices was proposed. We designed the quench detecting circuit and tested the performance of the circuit. The detecting circuit was consisted of Op-Amp and low pass filter etc, to detect very low voltage around $1{\mu}V$. The circuit detected effectively the low voltage when over current is applied to HTS tapes. At the next step, we are going to apply and test the circuit to protect the prototype HTS cable.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.961-963
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• 2002

When high temperature superconducting(HTS) tapes are wound on former for HTS cable application, their critical characteristics are likely to be degraded seriously because of mechanical stress. In this study, prior to fabricate prototype HTS cables, we investigated the variation of critical characteristics of HTS tapes according to their pitch angles. For this work, we prepared the samples of HTS tapes on the former of which diameter is 3cm. Pitch angles of HTS tapes are $0^{\circ}$, $00^{\circ}$, $20^{\circ}$, $30^{\circ}$, $40^{\circ}$, respectively. We applied current up to 160 $A_{rms}$ to HTS tapes and investigated E-I characteristics. The critical current of HTS tapes was decreased as pitch angle increased. In addition, when the applied current was beyond their critical current, the rate of resistance increase of HTS tapes was in proportion to their critical current. Finally, We concluded that the pitch angles affected resistance increase of HTS tapes as well as critical current.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.651-659
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• 2016

Korea Institute of Machinery & Materials (KIMM) has developed a high efficient Stirling cryocooler with moving magnet linear compressor for precooling hydrogen liquefier and cooling high temperature superconductor (HTS) devices, such as superconductor cable and superconductor fault current limiters. Hydrogen liquefier and HTS electric devices require cryocooler with cooling capacity of hundred watts to kilowatts at 77 K. The compressor in the Stirling cryocooler uses opposed moving magnet linear motors to drive opposed pistons. High efficient Stirling cryocooler is designed by SAGE-software, manufactured and tested systematically. A cooling capacity of 1 kW at 77 K with an electric input power of 9.6 kW has been analyzed. But prototype test results of the Stirling cryocooler have the cooling capacity of 0.65 kW at 76.8 K with an electric input power of 8.1 kW. And then, 21.5% Carnot COP (Coefficient of performance) of the prototype Stirling cryocooler is achieved. The comparison analysis between SAGE-model and experimental results has shown the direction for further design optimization of the Stirling cryocooler.