• Progress in Superconductivity
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• v.10 no.1
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• pp.55-59
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• 2008

A Superconductor Flywheel Energy Storage System(SFES) mainly consists of a pair of non-contacting High Temperature Superconductor(HTS) bearings that provide very low frictional losses, a composite flywheel with high energy storage density. The HTS bearings, which offer dynamic stability without active control, are the key technology that distinguishes the SFES from other flywheel energy storage devices, and great effort is being put into developing this technology. The Superconductor Journal Bearing(SJB) mainly consists of HTS bulks and a stator, which holds the HTS bulks and also acts as a cold head. Static properties of HTS bearings provide data to solve problems which may occur easily in a running system. Since stiffness to counter vibration is the main parameter in designing an HTS bearing system, we investigate SJB magnetic force through static properties between the Permanent Magnet(PM) and HTS. We measure stiffness in static condition and the results are used to determine the optimal number of HTS bulks for a 100kWh SFES.

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.22-22
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• 2006

• Progress in Superconductivity and Cryogenics
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• v.15 no.2
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• pp.44-47
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• 2013

Large AC loss from the second generation (2G) high temperature superconducting (HTS) wires has been one of the major bottlenecks in power applications with HTS materials. Moreover, the large power applications also require the large current capacity from the HTS wires, which makes them produce larger AC losses. In order to reduce the AC loss from the HTS conductors with large current capacity, an HTS compact cable with some striations on the superconducting layers has been proposed. In this paper, we prepared some sample HTS compact conductors with striations, and measured their magnetization loss from the external magnetic field. We also made some slits on the superconducting layer of the HTS wire by laser cutting to reduce the aspect ratio of the superconducting layers. It would make the low eddy current loss and magnetic decoupling. Finally, the magnetization losses of the sample HTS compact conductors were measured and analyzed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.265-266
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• 2006

Superconductor is developed for applications in high-power devices such as power-transmission cables, transformers, motor and generators. In such applications, HTS tapes are subjected to various kinds of stress or strain. In the fabrication of the devices, the critical current (Ic) of the high temperature superconductor degrades due to many reasons including the tension applied by bending, twist and thermal contraction. In particular manufactured HTS cable, we need pitch angle controls. This paper is analyzed that Ic characteristics is changed pitch angle of HTS tape. These results will amount the most important basis data in HTS cable.

• Progress in Superconductivity and Cryogenics
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• v.17 no.3
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• pp.18-22
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• 2015

This paper deals with high-Tc superconducting (HTS) power charging system with GdBCO magnet, photo-voltaic (PV) controller, and solar panels to charge solar energy. When combining the HTS magnet and the solar energy charging system, additional power source is not required therefore it is possible to obtain high power efficiency. Since there is no resistance in superconducting magnet carrying DC transport current the energy losses caused by joule heating can be reduced. In this paper, the charging characteristics of HTS power charging system was simulated by using PSIM. The charging current of HTS superconducting power charging system is measured and compared with the simulation results. Using the simulation of HTS power charging system, it can be applied to the solar energy applications.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.409-411
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• 2003

As power demand increases gradually, the call for underground transmission system increases. But it is very difficult and high in cost to construct new ducts and/or tunnels for power cables in metropolitan areas. HTS (High Temperature Superconducting) cable has the several useful characteristics such as increased power density. Therefore HTS cable can allow more power to be moved in existing ducts, which means very large economical and environmental benefits. In this paper, we carried out investigation for Application of 22kV class HTS cable in Korean utility networks. The results show that the HTS cable is applicable to replace IPB in pumping-up power plant, withdrawal line in distributed generation, withdrawal line in complex power plant, and conventional under ground cable. Finally, as the cost of HTS wire and refrigeration drops, the technical and economical potential of HTS cable is evaluated positively.

• Progress in Superconductivity and Cryogenics
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• v.22 no.4
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• pp.31-39
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• 2020

Power cables made of high temperature superconductors (HTS) are considered as most advanced applications of superconductivity for electro-energetics. Several cables made of the First Generation (1G) HTS wires have been produced and installed to electrical grids worldwide. Power cables made of the Second Generation HTS wires (2G or Coated Conductors) are in active development. Most basic principles of HTS power cables development have been published in many works since 90-ties. In this Review we would like to present our new developments mostly directed to 2G HTS compact power cables. We are presenting the methods to optimize a design of 2G AC compact power cable providing uniform current distribution among cable layers and the production technology approaches to implement such a design. AC losses measurements in such cables and other test methods are described. Some problems of the development 2G HTS power cables with small diameters are discussed. We presented as examples designs, developments and test results of two major coaxial cables designs: single-phase (cable core and a shield) and three-phase (triaxial: with three coaxial phases).

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.250-253
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• 2003

Rise of the current level at power applications, such as, transformer, motor and power cable, need for using stacked HTS tapes. In this paper, we measured losses of the stacked HTS tapes. Three different types of the stacks which were made of 2 tapes, 3 tapes and 4 tapes, were tested Perpendicular magnetic field was applied to the HTS stacks as the external magnetic field. Effects of the gap between HTS tapes were examined.

• Progress in Superconductivity and Cryogenics
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• v.18 no.1
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• pp.41-45
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• 2016

The technology of supplying the electric power by wireless power transfer (WPT) is expected for the next generation power feeding system since it can supply the power to portable devices without any connectors through large air gap. As such a technology based on strongly coupled electromagnetic resonators is possible to deliver the large power and recharge them seamlessly; it has been considered as a noble option to wireless power charging system in the various power applications. Recently, various HTS wires have now been manufactured for demonstrations of transmission cables, motors, MAGLEV, and other electrical power components. However, since the HTS magnets have a lower index n value intrinsically, they are required to be charged from external power system through leads or internal power system. The portable area is limited as well as the cryogen system is bulkier. Thus, we proposed a novel design of wireless power charging system for superconducting HTS magnet (WPC4SM) based on resonance coupling method. As the novel system makes possible a wireless power charging using copper resonance coupled coils, it enables to portable charging conveniently in the superconducting applications. This paper presented the conceptual design and operating characteristics of WPC4SM using different shapes' copper resonance coil. The proposed system consists of four components; RF generator of 370 kHz, copper resonance coupling coils, impedance matching (IM) subsystem and HTS magnet including rectifier system.

• Progress in Superconductivity and Cryogenics
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• v.16 no.2
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• pp.59-63
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• 2014

HTS power cable bypass the fault current through the former to protect superconducting tapes. On the other hand, the fault current limiting (FCL) power cable can be considered to mitigate the fault current using its increased inductance and resistance. Using the increased resistance of the cable is similar to the conventional resistive fault current limiter. In case of HTS power cable, the magnetic field of HTS power cable is mostly shielded by the induced current on the shield layer during normal operation. However, quench occurs at the shield layer and its current is kept below its critical current at the fault condition. Consequently, the magnetic field starts to spread out and it generates additional inductive impedance of the cable. The inductive impedance can be enhanced more by installing materials of high magnetic susceptibility around the HTS power cable. It is a concept of SFCL power cable. In this paper, a sample SFCL power cable is suggested and experimental results are presented to investigate the effect of iron cover on the impedance generation. The tests results are analyzed to verify the generation of the inductive and resistive impedance. The analysis results suggest the possible applications of the SFCL power cable to reduce the fault current in a real grid.