• Electrical & Electronic Materials
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• v.8 no.4
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• pp.451-457
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• 1995

Most important study on development of high-Tc superconducting magnet is magnetic properties with design conditions To study optimal design condition of high-Tc superconducting magnet, small size solenoid magnet was designed and simulated. Design conditions are radius of bobbin, radius of magnet, length of magnet, critical cur-rent and notch size. We know that intensity of magnetic fields was controled by critical current and uniformity of magnetic fields was controled by notch size. The optimal design conditions to get the high intensity and uniformity of magnetic field in this experiments were radius of bobbin=3[cm], radius of magnetic=12[cm], length of Z=10[cm], notch size=6[cm] and critical current=12[A].

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.9
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• pp.484-489
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• 1999

This paper deals with the design and fabrication of a heater-trigger type high-Tc superconducting power supply system, and characteristics have been analyzed through experiments. The high-Tc superconducting power supply consists of two heater trigger and electric magnet, and YBCO superconducting bulk. In this experiment, 0.6T class magnet and dc 2.3A heater current are used, and the current-pumping characteristics have been analyzed with computer aided sequence control system. Hall sensors are installed on the YBCO bulk and in the center of iron core in order to analyze the effect of the flux-pumping on the system with when magnet flux changes its value. In this experiment, maximum pumping-current has been achieved to about 6.6 amps.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.92-96
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• 2003

This paper deals with the characteristics of persistent current switch (rCS) system fer applied HTS magnet system. To apply the high-Tc superconductor in superconducting machine such as motror, generator, MAGLEV, MRI, and NMR, the study on high-Tc superconducting persistent current mode must be performed. In this experiment, the PCS system consists otd superconducting magnet, PCS and magnet power supply. The superconducting magnet was fabricated by connecting four double pancake coils (DPCs) in series. The PCS was inductive double pancake coil type and heated up by the SUS 303L tape heater. The optimal length of PCS was calculated and thermal quench state of PCS was simulated by using finite element method(FEM) and compared with experimental results. The optimal energy to normalize the PCS was calculated and introduced. Finally, the persistent current was observed with respect to various ramping up rate and magnitude of charging current.

• 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.

• 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.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.4
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• pp.159-164
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• 2002

This paper presents the design and fabrication of a high-Tc superconducting (HTS) power supply for charging of the HTS magnet load, and its characteristics have been analyzed through experiments. HTS power supply consists of two heaters, an electromagnet, a Bi-2223 solenoid and a Bi-2223 pancake magnet load. In this experiment, 331 mH electromagnet and 0.8 A dc heater current were used, and 8.5 sec and 17 sec were used for pumping period. Mechanism of the superconducting switch is used for heater-trigger. In order to measure the pumping-current with respect to the magnet flux changes, hall sensor was installed at the center of the Bi-2223 pancake load. The experimental observations have been compared with the theoretical predictions. In this experiment, the pumping-current has reached about 1.2 A. In computer simulation, the maximum pumping-current of the system has been predicted to be about 2.7 A.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.216-219
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• 2003

Persistent Current Switch (PCS) is used in many superconducting magnet system. To apply the high-Tc superconductor in superconducting machine such as motor, generator, MAGLEV, MRI and NMR, the study on the persistent current mode should be performed. Because persistent current mode provide best stability and homogeneous characteristics to the superconducting machine. To stabilize the superconductor system, it is important to estimate the length of PCS. If the proper length of PCS is too short, it cause serious injury to system in fault state. So we calculated the optimal length of PCS in this paper.

• Progress in Superconductivity and Cryogenics
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• v.14 no.3
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• pp.53-59
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• 2012

Adiabatic demagnetization refrigerator (ADR) for hydrogen re-liquefaction operating between 24 K and 20 K has been designed. $Dy_{0.9}Gd_{0.1}Ni_2$, whose Curie temperature is 24 K, is selected as a magnetic refrigerant. The magnetic refrigerant powder is sintered with oxygen-free high purity copper (OFHC) powder to enhance its effective thermal conductivity as well as to achieve relatively high frequency. A perforated plate heat exchanger (PPHE) operated with forced convection is utilized as a heat switch. The forced convection heat switch is expected to have fast response relative to a conventional gas-gap heat switch. A conduction-cooled high Tc superconducting (HTS) magnet is employed to apply external magnetic field variation on a magnetic refrigerant. $2^{nd}$ generation GdBCO coated conductor HTS tape with Kapton$^{(R)}$ insulation (SUNAM Inc.) will be utilized for the HTS magnet. The magnetization and demagnetization processes are to be achieved by the AC operation of the HTS magnet. The designed magnetic field and target ramp rate of the HTS magnet are over 4 T with 180 A and 0.4 T/s, respectively. AC loss distribution on HTS magnet is theoretically estimated.

• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.30-34
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• 2009

This paper deals with charging and persistent-current mode operating characteristics of BSCCO magnet load using high-temperature superconducting (HTS) power supply. The HTS power supply consists of two heater-triggered switches, an iron-core transformer with the primary copper winding and the secondary BSCCO solenoid, and a BSCCO magnet load. The magnet load was fabricated by double pancake winding and its inductance is about 21 mH. A hall sensor was installed at the middle of the magnet load to measure the current in the load. In order to investigate the efficient pumping characteristics, operating tests of heater-triggered switch with respect to dc heater current were carried out, and the electromagnet current was determined by considering saturation characteristics of its iron core. The saturation characteristics of charged current in the magnet load were observed with respect to various pumping periods: 12 s, 14 s, 24 s and 32 s. After charging the magnet load, the persistent current was measured. The operating characteristics of the persistent current mode were mainly determined by joint resistance and magnet load.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.192-197
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• 1994

High-Tc superconducting magnet properties were dependent upon design conditions such as its radius, length, critical current and notch size. In order to study, design and the simulation for small size magnet were implemented. We know that intensity of magnetic fields controled by critical current and factor ${\alpha}$( R$_2$/R$_1$) and uniformity controled by notch size. The optimal condition of intensity and uniformity magnetic field in this experiments are R$_1$=3[cm], R$_2$=12[cm], Z=10[cm], ${\alpha}$=4, notch=6[cm], critical current=12[A].