• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.213-215
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• 2003

This paper deals with the characteristics of a prototype solenoid for basic design of DC reactor type superconducting fault current limiter (SFCL). The prototype high-Tc Super-conducting (HTS) solenoid was manufactured with 4 stacked Bi-2223 tape. The critical currents were measured with respect to the number of stacks. In order to test the safety of HTS solenoid in quenched state, the transport tests of AC over-current were performed. These experimental results could be applied to the basic design of HTS DC reactor for SFCL effectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.8
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• pp.785-789
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• 2006

BiSrCaCuO(2223) superconductor was fabricated by the thermal pyrolysis method. The superconducting precursor produced by the dehydration of the gel at $120^{\circ}C$ for 12 h is not in the amorphous state as expected but in a crystalline state. In this paper, the establishment of fabrication condition was examined so as to improve the related properties to the practical use of BiSrCaCuO superconductor, and we reported the production of the BiSrCaCuO by the pyrolysis method.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.9-11
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• 2001

현 단계에서도 임계전류밀도가 약 $100A/mm^2$로 충분히 높아 전력분야 응용이 기대되는 Bi-2223테이프에 대한 교류손실을 초전도 전력기기의 실제 상황을 고려하여 측정하였다. 중요한 평가 결과로서는 먼저 통전손실 특성은 외부 교류자장의 세기뿐만 아니라 방향에 따라서도 매우 상이하였으며, 비교적 외부자장이 큰 경우는 동저항손실 메카니즘이, 작은 경우는 그 외의 또 다른 손실 메카니즘이 지배적이었다. 또한 수평자장에 대한 자화손실 특성은 코아 모델로부터 계산된 손실과 비교적 잘 일치하였다. 따라서 자화손실은 히스테리시스 손실 메카니즘이 지배적이라 할 수 있으며, 측정된 자화손실은 저온 초전도체에서는 볼 수 없었던 약한 주파수 의존성을 보였을 뿐만 아니라 외부자장의 세기에 따라서도 주파수 의존 특성이 상이하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1292-1298
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• 2003

In this paper, dc reactor lot the inductive high-Tc superconducting fault current limiter (SFCL) was optimally designed by finite element method(FEM). The Prototype high-Tc do reactor was manufactured and compared to the results of design. This dc reactor consists of 4∼stacked double pancake coils which are wounded with Bi-2223 wire coated with SUS315L. Kapton tape is used for the insulation of turn to turn and layer to layer. Each pancake is connected in series by soldering Finally, optimal design and manufacture method lot the dc reactor is suggested in this paper. Through the comparison of result of optimal design and experimental result of prototype high-Tc superconducting dc reactor, reliance on the design of the high-Tc dc reactor tot the 1.2 kV/80 A SFCL is proved.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2221-2223
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• 1999

Axial magnetic field($B_z$) generated by special electrode construction in vacuum interrupters(Vl) is used to extinguish electric plasma arcs because that restrains this form expending. So VI applied axial magnetic field has more interruption capacity as compared with other VI. Also, the profile of toroidal field($B_{\theta}$) generated by $B_z$, is important to VI design. In this study, it was represented that the behavior of vacuum arc. In addition, The relationship between $B_z$ and $B_{\theta}$ was represented by using Dynamo theory. I hope that this study will be a good data in design of vacuum interrupters.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.98-101
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• 2005

BSCCO thin films fabricated by using the evaporation method. As a result, although the composition of Bi2212 was set up, the phase of Bi2201, Bi2212 and Bi2223 was formed. The formation area of these stable phases is indicated as inclined line in the direction of the right lower end from the Arrhenius plot of the substrate temperature-oxidation gas pressure, and are distributed in very small area. The activation energy for the phase transformation from the Bi2201 to the Bi2212 is estimated in terms of the Avrami equation.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.681-682
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• 2006

This paper deals with the preliminary study on the HTSC levitation magnet for MAGLEV operating in persistent current mode (PCM). The high temperature superconducting (HTSC) levitation magnet consists of two single-pancake type coils wound with Bi-2223 wire and a persistent current switch (PCS). The levitation magnet was designed by using 3-D finite element analysis. The suspension system for high-speed electrodynamic suspension (EDS) maglev should operated in persistent current mode. It is important to develop a technology to minimize the joint resistance of splice between two HTSC wires. The PCS was observed with respect to various magnitude of charging current. Based on these results, the levitation system using HTSC wire will be further studied.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.817-818
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• 2006

A 2.0T class HTS conduction cooled magnet was designed. Designing of magnet shape was performed through two steps. First step is to find a basic cross section for minimize the amount of conductor used and second step to optimize the coil shape to satisfy the magnetic field homogeneity. The magnetic fields was analyzed with FEM and the critical current value of magnet was also expected with the result of field analysis and the Ic to B curve of Bi-2223 HTS tape.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2218-2223
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• 2008

A nose shape is strongly related with the aerodynamic performances of train. Therefore shape definition and aerodynamic performance analysis are important for train nose shape design. In this study, a new design method was suggested for train nose shape design by configuration function. To this end, the nose shape was classified by box type and each box shape is defined. After that the 3-D shape of train was defined as several mathematical functions by combination of each box shape. Also it was shown that the wind shield of driver's seat and complex curves of surface can be expressed using superposition of functions. This methodology can be used for grid generation of numerical analysis, and applied to aerodynamic optimization design of nose shape.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.352-354
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• 2010

The effects of Au addition on the structure and the superconducting properties of Bi system bulk have been investigated. Au exists in the metalic form in above materials. It does not affect the formation and structure of the BiSrCaCuO(2223) phase. The superconducting transition temperature Tc does not change for $Bi_{1.7}Pb_{0.3}Sr_2Ca_2Cu_3O$ composite However Au doping can make the grains smaller. Metallic Au can make gathers on the grains boundary and lead to the increment of critical transport current density. The current density of $Bi_{1.7}Pb_{0.3}Sr_2Ca_2Cu_3Au_{0.5}O$ was 1000A/$cm^2$ at liquid nitrogen temperature.