• 한국초전도학회:학술대회논문집
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• v.10
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• pp.241-247
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• 2000

77 K와 self-field에서 22 A 의 Ic 를 갖는 길이 120 m, 19-심 Bi-2223상 선재를 제조하여, 두 개의 double pancake 코일로 구성된 proto-type 고온초전도 자석을 설계, 제작하여 이 자석에서의 4.2 K와 77 K에서의 I-V 특성과 운전 특성을 평가한 결과, 이 자석은 77 K 등온조건에서는 9.5 A 의 Ic를, 77 K 헬륨가스 속에서는 8.3 A 의 Ic를 나타내었고, 4.2 K 등온조건에서는 93.7 A 의 Ic와 102 A 의 Iq를, 4.2K헬륨가스 속에서는 88.4A의 Ic 와 92.0 A 의 Iq를 나타내어, 이 자석은 4.2 K 와 77 K 의 등온조건에서 각각 0.58 T 와 0.06 T 의 자장을 발생하였는데, 이는 해석적 방법으로 계산한 결과와 잘 일치하였다. 그리고 이 자석이 전도냉각되어 4.2 K 에서 운전될 때의 안정성 특성평가로서, Ic 보다 약간 큰 전류인 89 A 를 인가한 결과, 전류인가 후 82.6초 후에 quench가 발생하였는데, 이 quench는 네 번째 pancake의 전류도입선부 연결부에서와 약간 늦지만 첫 번째 pancake의 전류도입선부 연결부에서 거의 동시에 개시되어 전체로 파급된 것으로 사료되었는데, Ic 가 낮은 첫번째 pancake에서 더 높은 전압 강하가 나타났다. 또한 장착된 heater를 통하여 77 K 에서 8.9 A 의 전류로 운전되고 있는 코일에 146 joule 의 열을 가했을 때 quench 가 일어났는데, 이때 quench 는 방위각 방향의 Bi-2223/Ag 선재를 따라서 보다 Kapton 절연층을 관통하는 선재의 반경방향으로 훨씬 빨리 전파하였다.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.835-837
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• 1998

Current lead plays the part of connector between ambient temperature and liquid helium superconducting magnet. Having zero resistance characteristic, it is expected that HTS has very low thermal conductivity and generate no joule heat when fabricated to current lead. In particular, among the HTS meterials, HTS tape has high Jc and Ag-sheath of tape plays the part of stabilizer, but it has too poor mechanical strength to be applied and when fabricated as long length tape, it has tendency to decline Jc seriously. In this study, we fabricated Bi-2223 multifilamentary tapes and then made current lead with stacking type using them. Through this work, we conclude that the defect of HTS long length tape is decreased by addition the number of stacking tape and that current lead is able to operate more stably by minimizing the gap of tapes.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.1050-1053
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• 1998

To be applied to electrical equipment HTSC tapes have to endure external stress and so on. The critical current density has been shown depending on the mechanical properties. strain and bending stress. AC loss reduction is primary concern in the development of such high-efficiency equipment. AC losses in Bi-2223 silver-sheathed tapes, both single and multi-filamentary, were investigated by means of AC magnetization techniques. The results were compared with the hysteresis loss equation based on Bean model and the eddy current loss equation. The AC loss of the mono-filamentary tape was the hysteresis. On the contrary, the AC loss of the multi-filamentary tape was substantially dominated by the eddy current loss in the Ag matrix.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.702-705
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• 1998

To be applied to electrical equipment HTSC tapes have to endure external stress and so on. The critical current density has been shown depending on the mechanical properties, strain and bending stress. AC loss reduction is primary concern in the development of such high-efficiency equipment. AC losses in Bi-2223 silver-sheathed tapes, both single and multi-filamentary, were investigated by means of AC magnetization techniques. The results were compared with the hysteresis loss equation based on Bean model and the eddy current loss equation. The AC loss of the mono-filamentary tape was the hysteresis. On the contrary, the AC loss of the multi-filamentary tape was substantially dominated by the eddy current loss in the Ag matrix.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.382-385
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• 1998

To be applied to electrical equipment HTSC tapes have to endure external stress and so on. The critical current density has been shown depending on the mechanical properties, strain and bending stress. AC loss reduction is primary concern in the development of such high-efficiency equipment. AC losses in Bi-2223 silver-sheathed tapes, both single and multi-filamentary, were investigated by means of AC magnetization techniques. The results were compared with the hysteresis loss equation based on Bean model and the eddy current loss equation. The AC loss of the mono-filamentary tape was the hysteresis. On the contrary, the AC loss of the multi-filamentary tape was substantially dominated by the eddy current loss in the Ag matrix.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.55-57
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• 2000

In this paper we present the results of tests for the high-Tc superconducting (HTS) power cable core. A prototype HTS cable cores have been constructed using Bi-2223 based Ag-sheathed HTS tapes. HTS cable cores has been tested at 77K with DC currents. Results shows that the cable cores carrying up to 700A DC and self-field effects are discussed.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.41-43
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• 1996

This paper describes on concerning electromagnetical and thermal behaviors during normal transition in Bi-2223/Ag superconducting multifilamentary tapes by conduction cooling. Some experiments were carried with operating temperature, 10-40K, and transport current as parameters in zero magnetic field. Sample tapes are transited normally with heater to intiate a quench. The voltage and temperature properties which accord to normal transition are measured by voltage taps and thermocouples attached to sample tapes, we also calculated longitudinal and transverse directions normal-zone propagation velocities from the voltage traces.

• Progress in Superconductivity and Cryogenics
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• v.2 no.2
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• pp.6-10
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• 2000

1.5 kA class HTS current leads for a SMES magnet, which are connected to a conventional vapor cooled copper leads, were designed. The HTS leads are composed of Bi-2223/Ag-Au tapes and a stainless stell tube. The estimated critical current of the lead is about 1.6 kA at 77.3 K and in a self magnetic field, and the heat input to the liquid helium from the cold end of the 35 cm lead is 0.4 W/lead. It has been made clear that the heat input decreases with increase of the lead length and decrease of the warm end temperature and Ag-Au/SC ratio.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.280-284
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• 2000

The prototype high-T$_c$ superconducting (HTS) power transmission cables have been designed and fabricated multi layers of spirally wound HTS tapes. The cables were made Bi-2223 based Ag-sheathed HTS tapes, and tested in LN$_2$. Critical currents of 700A dc and better were achieved. The magnetic flux density and field direction were analyzed in the cable configuration. In this paper the results of analysis and tests of HTS power transmission cables were described.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.8
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• pp.367-373
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• 2001

This paper presents racetrack High Temperature Superconducting (HTS) magnet with iron plates to achieve the maximum current-carrying capacity and the simple shape that can easily be wound and jointed. On the basis of the magnetic field analysis using Biot-Savart's law and 3 Dimensional Finite Element Analysis (3D FEA), this study is focused on the function of iron plates, which is to obtain smaller B${\perp}$, and stress and strain condition of Ag-sheathed Bi-2223 37-filament HTS tapes are considered. Moreover, the measured performance of the magnet with iron plates improved by 50% on the basis of initial magnet.