• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.603_604
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• 2009

HTS tape is developed for the purpose of being applied to the power cable, motor and generator, etc. The resistance of conventional power cables is not changed a lot by over current condition. But HTS(High temperature superconductor)power cable has some different properties. The impedance of superconductor is changed due to the magnitude of current, temperature, and magnetic field. And the characteristics analysis of HTS power cable under many kind of fault conditions are important to apply real system. In addition the magnitude of over current is 10 times larger than rated current. In this paper, the characteristics of HTS power cable are analyzed when over current flows. Model cable used 2G wires was made and experimented. The results will be helpful to manufacture real HTS power cable.

• 한국자기학회지
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• 제20권6호
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• pp.212-215
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• 2010

비정질 Ga 박막은 벌크에 비해 높은 초전도 임계온도와 임계자기장 값을 보이나 그 특성은 불안정하여 상온에 한번 노출되면 그 초전도 특성을 잃어버리게 된다. 이 논문에서는 Ga/Al 두층 박막을 제작하여 이러한 비정질 Ga 박막의 불안정한 초전도 특성을 개선할 뿐만 아니라 기존의 스핀검출에 응용되고 있는 Al 박막을 대체할 수 있는 가능성을 연구하였다. 극초진공 분자빔박막 증착장비(UHV-MBE)를 사용하여 Ga/Al 두층 박막을 제작하고, 표면의 적절한 플라즈마 산화 처리에 의한 Ga/Al/$Al_2O_3$/Fe의 터널 접합구조를 제작하여 Ga/Al 박막의 초전도 특성을 측정하였다. 한편, Ga/Al 박막의 표면 특성은 Auger 전자 분광기를 이용하여 분석하였다.

• E2M - 전기 전자와 첨단 소재
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• 제7권4호
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• pp.306-311
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• 1994

In this study, the influence of the powder sintering, the 2nd sinteiing and the grinding time on the Superconducting properties in the Bi(Pb)SiCaCuO Superconductor has been studied. From the analysis of SEM and XRD patterns, it was known that the sample prepared by the process of powder sintering has a porous microstructure with the critical temperature(Tc) below 77K, while the sample prepared by the 2nd sintering has a highly oriented microstructure with the Tc above 100K. The Critical Current Density(Jc) of the sample prepared by the 2nd sintering was better than the sample prepared by the process of powder sinteiing, but it's Jc, was low in practical use. Also, the effect of grinding time from 0[min] to 120[min] was investigated. As the grinding time is increased, the samples degraded from high-Tc phase to low-Tc phase and nonsuperconducting phases.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.189-1-190-1
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• 2008

A high temperature superconducting(HTS) power cable is available for high capacity current in normal condition. But resistance was appeared to operate unbalance load by thermal current characteristic. This characteristic of HTS power cable used to design for unstated condition. And than, It used to understand and analyze characteristic of power cable thermal and critical current. This study appeared that quench resistance reason from shield and former current rise to superconductor(SC) current. The resistance of SC occurred that the cable temperature rise to fault current after decreased critical current. The quench resistance of SC increased in temperature or decreased in critical current. So the quench resistance of SC correlated with resistance of both shield and former current. It need to sufficiently influenced the parameters of HTS cable design.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.284-285
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• 2005

Bi-2223 High-Temperature Superconducting(HTS) tape is one of the most widely used HTS tape for power application. Characteristics of the over current of HTS tape with different sheath are described. This paper presents the basic properties such as temperature and resistivity rise of the Bi-2223 HTS tape which is exposed to the over current. It is expected that results from this study can be utilized as basic data in designing superconducting power devices.

• 한국결정성장학회지
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• 제14권2호
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• pp.68-72
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• 2004

Sm 원소가 첨가된 $(Sm/Y)_{1.8}Ba_{2.4}Cu_{3.4}O_{7-x}$[이하 (Sm/Y)1.8] 고온초전도체를 국부용융성장법을 이용해 대기 중에서 용융성장실험을 하였다. 초기 (Sm/Y)1.8 초전도체 시편은 rubber 몰드를 이용해 냉간정수압성형(CIP) 과정을 거쳐 길이 방향 원통형상으로 제조되었다. 이렇게 얻어진 (Sm/Y)1.8 초전도체는 용융온도 및 성장속도에 따라 광학현미경, TEM그리고 SQUID magnetometer를 이용해 미세구조 및 초전도특성을 평가하였다. 이 결과 (Sm/Y)1.8 초전도체의 최적의 용융온도 및 성장속도는 $1085^{\circ}C$에서 3.5mm/hr로 나타났다. 특히 일방향으로 용융성장된 (Sm/Y)1.8 초전도체의 광학현미경 및 TEM에 의하 미세구조 관측 결과, 초전도상인 (Sm/Y)123 matrix내에 비초전도상인 (Sm/Y)211 inclusions이 균질하게 분포되어 있는 것이 관측되었다. 초전도특성을 평가한 결과 용융성장된 (Sm/Y)1.8초전도체는 90K에서 임계온도가 시작되어 77K이상의 온도에서 포화되는 특성을 보였다.

• 한국초전도저온공학회지:초전도와저온공학
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• 제5권1호
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• pp.10-17
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• 2003

For limitation and interruption of short circuit currents from low voltage to extra high voltage applications, the electrical equipment including fuses and circuit breakers, are widely used today. But in order to anticipate increasing needs for effective and competitive device for limiting the growing fault current in electrical power systems, fault current limitation technologies and fault current limitation devices are widely introduced and investigated in these days. Furthermore, the applications of high temperature superconducting materials (HTSC) into the current limiting devices are new approach for developing of novel and effective col-rent limitation electrical equipment. In this research, the necessities of current limitation technology and the developed and developing current limitation devices for power systems are introduced. Finally, the investigation of resistive type fault current limiters which is under development by LG and KEPCO were introduced.

• International Journal of Air-Conditioning and Refrigeration
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• 제14권3호
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• pp.94-101
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• 2006

A theoretical investigation to find thermodynamically optimum design conditions of conduction-cooled Peltier current leads is performed. A Peltier current lead (PCL) is composed of a thermoelectric element (TE), a metallic lead and a high temperature superconductor (HTS) lead in the order of decreasing temperature. Mathematical expressions for the minimum heat flow per unit current crossing the TE-metal interface and the minimum heat flow per unit current from the metal lead to the joint of the metal and the HTS leads are obtained. It is shown that the temperature at the TE -metal interface possesses a unique optimal value that minimizes the heat flow to the joint and that this optimal value depends on the material properties of the TE and the metallic lead but not the joint temperature nor electric current. It is also shown that there exists a unique optimal value for the joint temperature between the metal and the HTS leads that minimizes the sum of the power dissipated by ohmic heating in the current leads and the refrigerator power consumed to cool the lead, for a given length of the HTS.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.274-277
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• 2003

Critical current(Ic) degradation of HTS tapes after bending is one of the hottest issues in HTS development and application studies. Many people are measuring Ic degradations for effect of bending radius. However even if the bending radius is larger than the breaking radius a HTS tapes can be damaged by repetitive bending, which is unavoidable in the winding processes. Therefore, We studied the Ic degradation after repetitive bending. at 77K with self-field, of Bi-2223 tapes processed by "Powder-in-Tube" technique, which was made by America Superconductor Corporation(AMSC) and superconductiing tapes that strain is imposed measured critical current by temperature difference of L$N_2$ and normal temperature. Like this, critical current could measure that degradation about 1~3％ by temperature difference. These results will amount the most important basis data in power electric machine of superconductivity cable, magnet, etc that winding work is require.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.7-11
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• 1999

The recent progress in new cooling techniques of the high Tc superconductor(HTS) systems is reported and discussed with some practical examples. At the beginning stage of the HTS development in research laboratories, liquid nitrogen(LN$_2$) is the standard medium for an effective cooling. The success of HTS in many different application areas, however, has required a variety of need in the cooling temperature and the cooling capacity with specific design restrictions. While the utilization of alternative liquid cryogens such as liquid neon (LNe) or liquid hydrogen (LH$_2$) has been tired in some of them, even solid cryogens such as solid nitrogen (SN$_2$) or solid hydrogen (SH$_2$) may be another option in special applications. The gaseous helium cooled by a cryogenic refrigerator has also been a good candidate in many cases. One of the best cooling methods for the HTS is the direct conduction-cooling by a closed-cycle refrigerator with no cryogen at all. The refrigeration may be based on Joul-Thomson, Brayton, Stirling, Gifford-McMahon, or pulse tube cycles. The pros and cons of the newly proposed cooling methods are described and some significant design issues are presented.