• 한국전기전자재료학회논문지
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• 제11권7호
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• pp.565-570
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• 1998

Recently a few MJ superconducting magnetic energy storage ($\mu$ SMES) devices become commerci-ally available as one of the energy storage devices for uniterruptible power supply (UPS) systems. For such a ($\mu$ SMES) devics, a few kA class superconducting cables with high current density, high stability and excellent pulse characteristics are required. To acquire data for the superconduction cables related to design and fabrication of a 0.7 MJ $\mu$ SMES device, we tested critical currents and quench characteristics for several winding tensions and various remping rates especially. It is shown from the results that winding tensions have much influence on quench currents of the $\mu$ SMES devices.

• 한국전기전자재료학회논문지
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• 제16권5호
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• pp.424-428
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• 2003

The channel of a superconducting flux flow transistor has been fabricated with plasma etching method using a inductively coupled plasma etching. The ICP conditions then were ICP Power of 450 W, rf chuck power of 150 W, the pressure in chamber of 5 mTorr, and Ar : Cl$_2$=1:1. Especially, over the 5 mTorr, the superconducting thin films were not etched. The channel etched by plasma gas showed the critical temperature over 85 K. The critical current of the SFFT was altered by varying the external applied current. As the external applied current increased from 0 to 12 mA, the critical current decreased from 28 to 22 mA. Then the obtained trans-resistance value was smaller than 0.1 $\Omega$ at a bias current of 40 mA.

• 한국전기전자재료학회논문지
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• 제23권2호
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• pp.164-168
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• 2010

The transformer is expected to be an essential component of a superconducting fault current limiter (SFCL) for both the increase of its voltage ratings and the simultaneous quench due to different critical current between high-$T_C$ superconducting (HTSC) elements comprising the SFCL. However, in order to perform the effective current limiting operation of the SFCL, the design for the SFCL considering the hysteresis characteristics of the iron core is required. In this paper, the influence of the hysteresis characteristics of the iron core comprising the transformer type SFCL on its current limiting characteristics was investigated. Through the comparative analysis on the hysteresis curves due to the ratio of the turn number between the 1st and the 2nd windings of the transformer, the proper design condition for the ratio of the turn number to achieve the effective current limiting operation of the transformer type SFCL could be obtained.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.794-797
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• 2000

The fabrication of high quality superconducting thin films using pulsed laser deposition (PLD) has been reported to find optimized processing conditions and to make the millimeter-wave devices. High temperature superconducting (HTS) YBCO films were prepared on MgO (10${\times}$10${\times}$0.5mm) substrates by the PLD. The 3 pole bandpass filter with the center frequency of 22 GHz for satellite communication was designed consisting of hairpin coupled-lines to reduce the configuration in size. YBCO films are c-axis oriented and show superconductive transition temperatures of 88∼89 K with the transition widths < 0.5 K. The insertion loss of passband at 70 K was about 5 dB. The measured frequency response of superconducting filter will be compared with the simulation result.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.290-291
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• 2005

A high Tc superconducting with a nominal composition of $Bi_2Sr_2Ca_2Cu_3O_Y$ was prepared by the citarte method. The solid precursor produced by the dehydration of the gel at $120^{\circ}C$ for 12h is not in the amorphous state as expected but in a crystalline state. X-ray diffraction peaks of nearly the same angular position as the peaks of high Tc phase were observed in the precursor. After pyrolysis at $400^{\circ}C$ and calcination at $840^{\circ}C$ for 4h. the (001)peak of the high Tc phase was cleary observed. Experimental results suggest that the intermediate phase formed before the formation of the superconducting phase may be the most important factor in determining whether it is easy to form the high Tc phase or not. because the nucleation barriers of the two superconducting phase may be altered by the variation of the crystal structures of those intermediate phase.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.292-293
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• 2005

An electromagnetic memory effect observed in superconducting YBCO system was studied. From the measurement of differential conductance, it was cleared that the mechanism of electromagnetic memory can not be explained by using conventional flux flow model. By changing the density of external magnetic flux, changes in inductance of a coil in which a superconducting bar is inserted were also measured. It was concluded that the electromagnetic memory effect aries from the interaction between the trapped magnetic flux and the weak link of the filament formed in the superconducting bar.

• 한국전기전자재료학회논문지
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• 제23권1호
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• pp.42-47
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• 2010

The power burden of high-$T_c$ superconducting (HTSC) elements comprising superconducting fault current limiter (SFCL) using magnetic coupling of shunt reactors was analyzed. The magnetically coupled shunt reactors play a role in distributing the even power burden between HTSC elements comprising the SFCL, which contributes to the effective current limiting and recovery characteristics of the SFCL. It was confirmed through the comparative analysis on the SFCLs with both the magnetically coupled and the magnetically uncoupled shunt reactors that the magnetically coupled shunt reactors could improve the SFCL's performance by equalizing the power burden of HTSC elements.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2008년도 High Temperature Superconductivity Vol.XVIII
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• pp.71-71
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• 2008

• 한국초전도ㆍ저온공학회논문지
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• 제10권2호
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• pp.1-11
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• 2008

The application of bulk superconducting materials to electrical power systems is very attractive because bulk high temperature superconductors offer excellent electromagnetic properties. In recent years there has been significant progresses in the research and fabrication of superconducting bulk materials. Numerous efforts have been made worldwide to make bulk YBCO as a replacement of the conventional magnets to produce larger magnetic field and hence to improve the device performance in electrical power applications. This paper gives a comprehensive review of different applications of bulk HTS materials, concentrating in three areas including superconducting bearing, superconducting motors and high field magnets. The advantages of applying superconducting material into each application are analysed. The status of current research in each section is summarized and examples are given to demonstrate how YBCO bulk materials can benefit the design of electrical devices. Several numerical models which calculate the electromagnetic properties of bulk superconductors are introduced and finally the article concludes with a review on the studies of the demagnetisation effect in superconducting bulk magnets which is extremely relevant to applying superconducting technology to rotating machines.