• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.345-348
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• 2004

For practical applications, the evaluation of reliability or endurance of HTS conductors is necessary. The mechanical properties and the critical current, $I_c$, of multifilamentary Bi-2223 superconducting tapes, externally reinforced with stainless steel foils, subjected to high cycle fatigue loading in the longitudinal direction were investigated at 77K. The S-N curves were obtained and its transport property was evaluated with the increase of repeated cycles at different stress amplitudes. The effect of the stress ratio, R, on the $I_c$ degradation behavior under fatigue loading was also examined considering the practical application situation of HTS tapes. Microstructure observation was conducted in order to understand the L degradation mechanism in fatigued Bi-2223 tapes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.285-286
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• 2008

In practical applications of HTS tapes for electric devices such as coils and power cables, the jointing of HTS tapes is needed. In magnet applications superconducting joints are needed to achieve very low resistance at the joint, but for power device applications, a slightly higher joint resistance may be acceptable. In this study, an economical joint with good mechanical and electrical integrity could be achieved for Bi-2223 tapes which can be applicable to electric power applications. A lap joint method has been used. The joint resistance and strength of the jointed Bi2223 tapes have been evaluated. Electro-mechanical properties of the joint sample under tension have been examined and compared with the case of the single tapes.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.134-138
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• 2003

The influences of mixed mode of bending-tension on the Ic degradation and their interaction on the strain effect were evaluated in this study. A test fixture which applies a mixed deformation mode of bending-tension to HTS tapes has been newly devised. When the strain induced in the tape due to the mixed deformation mode was expressed as a total tensile strain, the irreversible strain to the critical current degradation of Bi-2223 tapes increased when compared with the case of simple bending mode, and the value at both ends were larger than that at the central region of the bend part. The Ic degradation behavior at the region exceeding the irreversible strain showed quiet a rapid drop of the Ic when compared with the simple bending cases. As the applied bending strain increased namely as the diameter of mandrel adopted decreased, the apparent irreversible strain of Bi-2223 tapes increased However, the increment decreased as the mandrel diameter decreased. As a result, it could be found that the tension to be applied to the Bi-2223 tapes during cabling of HTS tapes should be smaller, as the mandrel diameter becomes smaller.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.89-90
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• 2006

In this paper, the authors propose the RTDS (Real Time Digital Simulator) simulation method which puts a real HTS (High Temperature Superconducting) tape into the simulated voltage feedback system of HTS tape. To perform the RTDS based simulation, the voltage feedback system of HTS tape with hardware is designed and connected to the RTDS. This simulation method is the world first in order to obtain much better for installation of HTS power cable into a utility network.

• Progress in Superconductivity and Cryogenics
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• v.6 no.4
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• pp.22-26
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• 2004

For practical applications, the evaluation of reliability or endurance of HTS conductors is necessary. The mechanical properties and the critical current, Ie, of multifilamentary Bi-2223 superconducting tapes, externally reinforced with stainless steel foils, subjected to high cycle fatigue loading in the longitudinal direction were investigated at 77K. The S-N curves were obtained and its transport property was evaluated with the increase of repeated cycles at different stress amplitudes. The effect of the stress ratio, R, on the Ie degradation behavior under fatigue loading was also examined considering the practical application situation of HTS tapes. Microstructure observation was conducted in order to understand the Ie degradation mechanism in fatigued Bi-2223 tapes.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.170-172
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• 2000

This paper deals with the characteristic analysis of the flux damper with respect to the load, and the stability of Ag/Bi-2223 tapes in a high-Tc superconducting (HTS) synchronous motor. To find out the magnetic field distribution in a detailed model of the actual motor, the experimentally measured currents of the armature and the field windings are used as input parameters. The simulation results show that the flux damper shields the time varying field up to 10%, reduces armature reactance during the motor operation and during load changes, improving the stable motor operation. And it was observed that the flux damper generates loss by means of leakage flux, but this is not significant and it doesn't degrade the performance of the TS synchronous motor.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.603-604
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• 2000

Bi-2223 테이프는 송전케이블과 같은 저 자장 전력시스템의 응용에 가장 유망한 선재로 알려져 있다. 송전케이블에 교류 전류가 인가되면 인접한 테이프에 의해서 발생되는 자계는 통전손실에 영향을 미치게 된다. 이와 같은 실제 송전케이블의 응용 측면을 고려하여 좌측 및 상부인접전류가 통전손실에 미치는 영향에 대하여 조사하였다. Bi-2223 테이프의 통전손실은 교류 인접전류가 증가함에 따라서 급격하게 증가하는 반면, 직류 인접전류의 영향은 무시 가능한 정도로 작았으며, 인접전류가 큰 경우는 테이프의 배열에 무관한 반면 작은 경우에는 상부배열인 경우의 영향이 큼을 알 수 있었다. 또한 Bi-2223 테이프의 통전손실은 교류 인접전류의 주파수에 무관함을 알 수 있었다.

• Proceedings of the KIEE Conference
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• summer
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• pp.1121-1123
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• 2004

Characteristics of the break down current of HTS tape with different insulator are described. The various insulators are utilized for enduring the high voltage in superconducting power devices. The break down current of HTS tape largely depends on insulators wound round HTS tape. In this research, The break down currents of Bi-2223 tape, which is widely used for superconducting power devices are tested and discussed. It is expected that results from this study can be utilized as basic data in designing superconducting power devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.452-455
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• 2000

Superconducting power cable is one of the most promising energy application of high-T$_{c}$ superconductors (HTS). A prototype HTS cable have been constructed multi-layer cable using Bi-2223 tape and tested. The AC transport losses under self field were investigated at 77K on the 19 filamentary tape and multi-layer HTS cables. And we carried out numerical analysis using bean model. The result shows that the total transport current of HTS cable in L$N_2$ was 475[A], and transport current passed through almost the outer layer (2-layer). Also, AC transport losses in outer layer of HTS cable was proportion to I$^2$ and higher than losses of inner layer. In case of Ip=Ic, calculated numerical loss density was concentrated on the edge of tape and most of loss density in cable was distributed outer layer more than inner layer. As magnetic distribution was concentrated on outer layer.r.

• Progress in Superconductivity and Cryogenics
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• v.11 no.3
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• pp.6-9
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• 2009

The thermal characteristics of quench propagation is a crucial problem for the stability of the superconductor. The objective of this study is to simulate the quench propagation with the variation of disturbance energy in Bi-2223/Ag HTS pancake coil. In this analysis, the temperature-time trace of a point away from heater was calculated under conditions of different quench energy. The critical disturbance energy between quench propagation and quench recovering was calculated, In addition, the minimum quench energy with different transport currents was obtained through the present simulation. These results are significant to the application of HTS.