• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.40-43
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• 2003

An electric propulsion system integrated with the ship service distribution system offers the naval architect considerable flexibility, and often the choice of a more affordable ship to acquire and operate as compared to a segregated mechanical drive option. United States of America navy announced in 2000 that they selected the electric propulsion system on next generation warship. Specially there is excellent advantages in superconductivity motors which can have higher efficiency, less vibration and noise, smaller dimensions compared with the conventional motors. The 5 MW HTS motor for warship test of electric propulsion was developed and tested. Also it was contracted between AMSC and United States of America navy to develop a 36.5 MW HTS motor in 3 years since March 3, 2003. This paper deals with the technical development tendency of HTS motors in foreign countries as well as in domestic, and it is focused on the application of HIS motors to the electrical propulsion system.

• Progress in Superconductivity and Cryogenics
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• v.11 no.4
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• pp.29-32
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• 2009

This paper proposes the bus-tie application scheme of 154 kV SFCL (superconducting fault current limiter) in Korean power system. The reduced amount of fault current by SFCL is different by where the SFCL is installed. Therefore the inflow ratio of fault current (IRFC) is suggested to consider the effect of an SFCL's location. The proposed scheme was applied to the Korean Power System of 2010, and fault currents were calculated and analyzed with this coefficient. Simulations show that the location with high IRFC is adequate to install SFCL but more consideration of other things is required to determine the location and capacity of SFCL.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.378-381
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• 2002

The helium liquefier was installed for 7.5 T superconducting wiggler, which is a source of synchrotron radiation, in Pohang Accelerator Laboratory (PAL) in 1995. It is MODEL 1410 fabricated by LINDE (old PSI America) of which capacity is about 17 liter per hour in normal mode and 47 liter per hour with liquid nitrogen pre-cooling. In addition to SC wiggler, we are anticipating that some devices related to electron accelerator are to be upgraded with superconducting application in order to improve the quality of photon beam.

• Progress in Superconductivity and Cryogenics
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• v.7 no.2
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• pp.47-51
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• 2005

This paper is for studying the feasibility of SFCL application for the interconnection operation of 154kV power systems under 345kV S/S in Korean power system. All Korean 154kV power systems are constructed as loop systems in downtown. However, the present 154kV systems are operated with separated systems around 345kV S/S because of fault current and overload problems. In this study, we investigate the structure and operation of 154kV power system in Seoul and study the feasibility of interconnection operation of 154kV systems under 345kV systmes by applying SFCLs to 154kV bus-tie.

• Progress in Superconductivity and Cryogenics
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• v.13 no.4
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• pp.1-4
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• 2011

From the viewpoint of high field application, the mechanical and critical current properties of recently developed $REBa_2Cu_3O_y$ (RE123, RE: rare-earth) coated conductors are summarized. In addition, effective flux pinning mechanisms in RE123 are also introduced. As one of the examples for high field application, the upgrading of the 18 T cryogen-free superconducting magnet is shown. The large anisotropy of $J_c$ is a problem at low temperature and high magnetic field. The nanorod is considered as the useful methods to improve the anisotropy of $J_c$, although its efficiency becomes small at low temperature.

• Progress in Superconductivity and Cryogenics
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• v.17 no.1
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• pp.40-43
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• 2015

Wireless power transfer technology is using the magnetic resonance recently drawing increased attention. It uses the resonance between transmitter and receiver coils to transfer power. Thus, it can improve the transfer distance and efficiency compared with the existing magnetic induction technique. The authors found from the previous study that the application of the superconductor coil to the magnetic resonance wireless power transfer system improved its efficiency. Its application to real life, however, requires the additional study on the effects of adjacent materials. In this study, the two resonance coils made by superconductor coils were used to aluminum and plastic shielding materials was placed between the coils. S-parameters were analyzed according to the position of the shielding material between the transmitter and receiver coils. As a result, the plastic of shielding material had no effect, but the aluminum of shielding material affected the wireless power transfer due to the shielding effectiveness.

• Proceedings of the KIEE Conference
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• summer
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• pp.427-429
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• 2004

As the load density of KEOCO system is higher, the fault current can be much higher than SCC(Short Circuit Capacity) of circuit breaker. Even though there are several alternatives to reduce fault current, as the superconductivity technology has been developed, the HTS-FCL (High Temperature Superconductivity Fault Current Limiter) can be one of the attractive alternatives to solve the fault current problem. This study presents the application of HTS-FCL in real customer system.

• Progress in Superconductivity and Cryogenics
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• v.7 no.1
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• pp.51-56
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• 2005

The recovery time of developing SFCL(Superconducting Fault Current Limiter) has an uncertainty. In general, the recovery time is estimated at 1 sec and more, even though the Process of SFCL technology is considered. However, auto reclosing time of circuit breaker is 0.3 sec in Korean power system. It is impossible to apply only one SFCL to power system because the recovery time is over the reclosing time of protection system. This study proposes two new SFCL systems for power system application. The proposed systems consider auto reclosing action for the protection in practical power system and consist of tow parallel SFCLS.

• Progress in Superconductivity and Cryogenics
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• v.12 no.3
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• pp.39-43
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• 2010

In Korea, 22.9kV hybrid SFCL (Superconducting Fault Current Limiter) has been developed and carried out long-term field tests in Gochagn power test center of KEPCO through DAPAS program. The SFCL will be installed at a distribution line of Icheon substation in Korea. For the successful application, we have to design the specifications considering real power system operation. This paper proposes a concept of the operating current based rms value for the protection coordination with protective delays and studies a proper range of the current in Korean distribution power system.

• Progress in Superconductivity and Cryogenics
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• v.12 no.1
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• pp.17-21
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• 2010

In the case of designing superconducting power apparatuses using the second generation high temperature superconducting wire, it is necessary to have a tape-splicing technique to achieve low splice resistance between coated conductor (CC) tapes. In this paper, an experimental splice method between YBCO CC tapes is proposed for a coil application. Splices were performed with a 37Pb-63Sn solder. YBCO samples were fabricated with various pressures and cooling rates. Joint resistances of the spliced samples of jointed YBCO CC tapes were measured and evaluated from V-I curves. In addition, optical micrographs were obtained to analyze the cross sectional microstructure of jointed samples.