• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.84-88
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• 2001

The optimum cross-sectional area Profile of gas-cooled high-temperature superconductor (HTS) current lead is analyzed to have minimum helium boil-off rate. The conventional constant area HTS lead has much higher helium consumption than the optimum HTS lead considered in this study. The optimum HTS lead has variable cross-sectional area to have constant safety factor. An analytical formula of optimum shape of lead and temperature profile are obtained. For multi-step HTS current leads, the optimum tape lengths and minimum heat dissipation rate are also formulated. The developed formulations are applied to the Bi-2223 material, and the differences between constant area, constant safety-factor, and multi-step current leads are discussed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.9
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• pp.572-577
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• 2000

This paper describes the test results of a single phase 3kVA high temperature superconducting power transformer. The tapes are made with Bi-2223 and have silver alloy as the matrix. Four double pancake windings are used. Among them two double pancake windings are connected in series for high voltage winding and the others are connected in parallel for low voltage winding. The rated voltage and current of primary winding and secondary winding are 220/110V. 13.7/27.3A. Fundamental characteristics are obtained through short circuit and no load test. The over load capability and characteristics are investigated.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.136-138
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• 2000

1.5kA HTS current leads for a superconducting magnetic energy storage(SMES) magnet, which are connected to a conventional vapor cooled copper leads, were designed. The HTS lead composed of cylindrically arranged Bi-2223/Ag-1 at5Au tapes and a stainless steel tube. The minimum operating current of the lead is 1.71 kA at 77.3K, self magnetic field, and the heat input to the liquid helium from the clod end of the 36 cm lead is 0.5 W/lead.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.19-21
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• 2000

We are developing portable type HTS magnet system cooled by solid nitrogen. This system have recooling and recharging capabilities. In this paper, we report preliminary test results obtained from the experimental solid nitrogen system and pancake magnet would with Bi-2223/Ag tapes, respectively. The operation period was sensitively dependent on the vacuum rate n the cryostat, size of SUS tube for flowing N_{2}$, and liquid nitrogen to cool the cryostat. The fabricated coil I_{c}$was 75 A at 20 K in self field.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.33-35
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• 1999

This paper describes the test results of the single phase 3kVA high temperature superconducting power trans-former. The tapes are made with Bi-2223 and have silver alloy as the matrix. Four double pancake windings are used in total. Among them two double pancake windings are connected in series for high voltage winding and two double pancake windings are connected in parallel for low voltage winding. The rated voltages of each winding are 220/110 V. Fundamental characteristics are obtained through short circuit and no load tests. The over load capability and characteristics are investigated.

• 한국초전도학회:학술대회논문집
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• v.12
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• pp.78-78
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• 2002

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.34-37
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• 1994

.In this study, we measured Ic depending on a curvature radios of High Tc superconducting tapes which were made of a single wire, two and three WIT(wire in tube). Wires are manufactured by the process of press ins and sintering (150h, at 845$^{\circ}C$ ) for the growth of 2223 high Tc Bi superconducting phase. We know that Ic of a single wire decrease with reduction of a curvature radius. The maximum Ic of 2 WIT wire is 2.54 (A) and have a better characteristic than a single wire (0.89 A) at a curvature radius 75mm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.244-245
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• 2007

Specially, High Temperature Superconducting power-transmission cable(HTS cable), 3-phase 100m long, 22.9kV class HTS power transmission cable system have been developed by Korea Electrotechnology Research Institute (KERI) and LS cable Ltd. that is one of 21st century frontier project in Korea. This cable was installed in KEPCO(Go-chang) testing site. In case of manufacturing HTS cable, superconducting joint is very important because they need very long tapes. Therefore, this paper gives some investigation of AC Loss in joined HTS tape by using several joint methods. Finally, this paper was shown background data for the form of HTS cable joint.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.822-824
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• 2000

To apply HTS to AC devices, it is necessary that study theoretically and experimentally to analyze the AC losses. It should be investigated the theoretical mechanisms precede the actual experiments. Because the AC losses cause some complicated troubles in AC machines, we can design the machines properly. In this study, firstly we analyze the basic cause of AC losses by investigating the several loss factors, secondly measure the AC losses of HTS by using Magnetization. Technique and this results show that AC losses of HTS is tenuous than those of general materials used in power system. Consequently we can compare the actual results with the theoretical results. And we find that AC losses of HTS are related to the amplitude of external magnetic field and the frequency. Through this study, we find that it is possible to apply the results by Magnetization. Technique to the AC power system, to the design of AC machine, to design of HTS proper to the foretold AC losses.

• Progress in Superconductivity and Cryogenics
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• v.15 no.2
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• pp.24-28
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• 2013

In this study, the homogeneity of critical current, $I_c$, along the lengthwise direction in the coated conductor (CC) tape under uniaxial tension was investigated using a multiple voltage tap configuration. Initially, a gradual and homogeneous $I_c$ degradation occurred in all subsections of the tape up to a certain strain value. This was followed by an abrupt $I_c$ degradation in some subsections, which caused scattering in $I_c$ values along the length with increasing tension strain. The $I_c$ degradation behaviour was also explained through n-value as well as microstructure analyses. Subsections showed $I_c$ scattering corresponding to damaged areas of the CC tape revealed that transverse cracks were distributed throughout the gauge length. This homogeneous $I_c$ degradation behaviour under tension is similar with the case under torsion strain but different with the case under hard bending which were previously reported. This behaviour is also different with the case using Bi-2223 HTS tapes under tension strain.