• Progress in Superconductivity and Cryogenics
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• v.19 no.4
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• pp.26-30
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• 2017

The promising characteristics of 2G high-temperature superconductor (HTS) coated conductor (CC) tapes have made it possible to apply to various electrical device applications. In this study, the mechanical and electromechanical properties of Sn-Cu double layer stabilized GdBCO CC tapes have been characterized. The stress and strain tolerances of $I_c$ in GdBCO CC tapes adopting stainless steel substrate were evaluated using $I_c$-strain measurement at 77 K under both uniaxial tension and monotonic bending conditions. The results were compared to the conventional single Cu layer stabilized CC tape. As a result, the Sn-Cu double layer stabilized GdBCO CC tapes showed somehow lower or comparable electromechanical properties as compared to the Cu stabilized CC tape ones.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.114-118
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• 2002

This paper were investigated discharge characteristics in the Liquid Nitrogen($LN_{2}$) noticed as a cooling medium of high temperature superconductor, and the characteristics of surface discharge and tracking phenomena on the solid insulators of cryocable. In order to investigate the bubbles which have much influence on electric surface discharge in Liquid Nitrogen, knife type electrode and plane electrode was formed oppositely with mode A and B, C configuration. It is considered that these result are fundamental data for electric insulation design of superconductivity and cryogenic application machinery which will be studied and developed in the future.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.294-296
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• 2002

Considering the application of high temperature superconductor to MRI, the loss at conductor joint would be very important. Therefore, we have carried out a measurement of joint resistance of Bi-2223/Ag tapes at 77 K. A pancake coil was wound by Bi-2223/Ag tape. Both ends the tape were overlapped and soldered to each other. The DC current is induced in the pancake coil by energizing the excitation coil wound by copper wire closely located to the pancake coil. The decay behaviour of the current in coils was clearly separated in two regimes, and initial fast decay of the order of minutes followed by a slow logarithmic-like decay, From this data, the resistance of the joint was evaluated as 2.74 n$\Omega$.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1996.11a
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• pp.116-121
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• 1996

An image of future power system which has introduced superconducting generator, cable, transformer, fault current limiter, SMES and so on is presented. Conceptual designs of each SC machines and devices are carried out. The SC cable and SFCL utilize the high Tc superconductor(HTS) cooled by liquid $N_2$Other devices use low temperature superconducting cooled by He. The SC power system models are proposed detailedly. In viewpoint of the operation and control SC power system, The concrete design direction and effective role of each SC apparatus are investigated. In this paper, it is pointed that superconducting fault limiters(SFCLs) should play an important part of the quenching current level coordination to prevent the other SC devices from quenching. Finially, SFCL are also expected to he very effective to introduce flexibility of power system configuration and operation due to their possibility to enhance transient stability and reduce short circuit current.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.824-825
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• 2011

This paper reports advantages of an insulationless high temperature superconductor (HTS) pancake coil compared with an insulated HTS pancake coil. The various characteristics of the insulationless HTS pancake coil were evaluated under charge-discharge conditions. Also over-current test was performed and the results were analysed to demonstrate that in terms of stability insulationless HTS pancake coil outperforms existing insulated HTS pancake coil.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1013-1014
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• 2011

급격한 산업 발전으로 전려계통의 수요 증가가 꾸준히 증가하고 있으며, 2007년부터 2020년까지 매년 2.2%씩 증가할 것으로 예상된다. 전력계통의 증대로 고장전류의 크기도 더불어 증가하고 있으며 이는 기존의 차단의 부하 용량을 넘어서고 있다. 따라서 안정적이고 효율적인 고장전류 차단을 위해서 초전도 한류기의 필요성이 대두되고 있다. 본 연구는 다양한 초전도 한류기 중에서 순수 저항형 초전도 한류기의 적용 가능한 2세대 고온 초전도 선재들의 특성을 파악하였다. 현재 상용화가 이루어지고 있는 2세대 고온 초전도 선재의 동작 온도에 따른 온도별 비저항, 임계전류, 교류 손실과 단위 길이당 인가 허영 전기장을 을 측정하였다. 상위 과정을 통해서 측정된 각 선재별 특성을 바탕으로 초전도 저항형 한류기에 적용 가능한 선재를 제안하고자 한다.

• Progress in Superconductivity
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• v.13 no.2
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• pp.65-84
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• 2011

Study of superconductivity in layered iron-based materials was initiated in 2006 by Hosono's group, and boosted in 2008 by the superconducting transition temperature, $T_c$, of 26 K in $LaFeAsO_{1-X}F_X$. Since then, enormous researches have been done on the materials, with $T_c$ reaching as high as 55 K. Here, we review briefly experimental and theoretical results on atomic and electronic structures and magnetic and superconducting properties of FeAs-based superconductors and related compounds. We seek for clues for unconventional superconductivity in the materials.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.165_166
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• 2009

A HTS(High Temperature Superconductor) Cable is regarded as the most underground power to respond higher power density delivery system. This paper discussed electrical characteristic and standards of HTS Cable system. Various HTS cable characteristics are examined[3-5], ad compared with XLPE cable characteristics on possible distribution system environment. HTS cable is required to stabilize thermal condition for superconducting status, possible improper operating condition which affects quench, unbalanced, and harmonics impacts are discussed. HTS cable is customer designed cable which shall be implemented in special requirement of power system, the standard origination process requires to establish a series of methodology including design manufacturing, testing and installation.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.720-722
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• 2001

The high temperature superconductor transformer gains interests from the industries. This paper examined characteristics of the laboratory scale three phase HTS transformer and Brandt equation is used to calculate the loss by perpendicular magnetic field in transformer winding. To estimate the performance of the three phase HTS transformer no load characteristics, short circuit characteristics are calculated by using finite element method. Transient characteristics of sudden short circuit during full load operation have been examined. Effect of the resistance growth in the HTS wire from the quench of the wire is included in the calculation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.4
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• pp.333-338
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• 2007

The object of this study is to find the optimal insulation design conditions of a HTS power cable cryostat. The optimum condition of a cable cryostat is obtained by varying types of MLIs, cable core weights, spacer diameters, winding pitches and MLI layer numbers. As the weight of cable core is increased, conduction heat transfer from surroundings to cable cryostat is increased. But as the spacer pitch is increased from 120 mm to 200 mm, the heat leak of cable cryostat remains almost constant. The optimal number of MLI layers is suggested. Double ply MLI is more effective than triple ply MLI and the insulation effect is best when the number of MLI layers is 36.