• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1339-1341
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• 1997

The various type Ag sheathed Bi-2223 tapes have been were fabricated by Powder-in-tube(PIT) process. The critical current density could be improved with the value of $23,000\;A/cm^2$(77 K, zero field) in the single concentric Bi-2223 tape. The bending property dependence of $I_c$ was improved in the double concentric Bi-2223 tape compared with single filamentary and single concentric one.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2018년도 제58차 하계학술대회논문집 26권2호
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• pp.179-180
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• 2018

자계 검출 센서는 여러 가지 종류가 있으나 벽면에 흐르는 미소 자계 및 차폐 전선에서 검출이 가능한 구조는 초전도 양자 간섭 소자(SQUID)가 주로 사용되지만 가격 및 물성 재료 특성으로 인하여 특수 용도로 사용되고 있다. 이에 본 연구에서는 전선으로부터 발생되는 저주파 자장을 검출할 수 있고 휴대성 및 가격이 저렴한 구조인 코일형 자계측정기를 개발하기 위해 자기 코어 및 코일 Turn수 변화에 따른 자계 검출 감도를 조사하여 최적의 구조를 설정하였다.

• 전기학회논문지P
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• 제61권4호
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• pp.214-219
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• 2012

In this paper, the method of protective coordination is studied to install Superconducting Fault Current Limiter (SFCL) to power distribution system. If SFCL is installed, the protective coordination is not operated well because of the decreased fault current. Thus, the resetting method of protective devices is presented to coordinate protection system in power distribution system with resistor-type SFCL. The presented methods are divided into three parts; OCR, OCR-Recloser, OCR-Recloser-Recloser. The presented methods are proved through case studies using PSCAD/EMTDC simulation.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.332-334
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• 2003

A subcooled liquid nitrogen cryostat is required for the cooling of a 6.6 ㎸, 200 A resistive type superconductive fault current limiter (SFCL). To help understand and design an appropriate cryostat for SFCL a prototype cryostat was fabricated and tested. Several states of subcooled liquid nitrogen were obtained by using cryocooler and helium gas. The temperature was uniformly distributed inside the liquid nitrogen vessel within the range of 0.4 K proving the effectiveness of the conduction cylinder.

• Structural Engineering and Mechanics
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• 제4권6호
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• pp.613-630
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• 1996

The homogenization method is used to develop a beam element in space for thermo-mechanical analysis of unidirectional composites. Local stress and temperature field in the microscale are described using the function of homogenization. The global (macroscopic) behaviour of the structure is supposed to be that of a beam. Beam-type kinematical hypotheses (including independent shear rotations) are hence applied and superposed on the microdescription. A macroscopic stiffness matrix for such a beam element is then developed which contains the microscale properties of the single cell of periodicity. The presented model enables us to analyse without too much computational effort complicated composite structures such as e.g. toroidal coils of a fusion reactor. We need only a FE mesh sufficiently fine for a correct description of the local geometry of a single cell and a few of the newly developed elements for the description of the global behaviour. An unsmearing procedure gives the stress and temperature field in the different materials of a single cell.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권1호
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• pp.27-31
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• 2000

This paper presents the performance evaluation of an HTS transformer. Numerical calculation by finite element method was used to evaluate the performance. BSCCO-2223 HTS tapes and double pancake winding were adopted in this design. Four double pancake windings were used in total. Among them two windings were connected in series for high voltage winding and two windings are connected in parallel for low voltage winding. Propertied of various type of the winding arrangement were examined. Characteristics of the transformer during the transient which was caused by sudden short were simulated. The current limiting effect, temperature rise and resistance growth of the superconducting winding were shown.

• 한국항해항만학회지
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• 제28권2호
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• pp.141-148
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• 2004

The observations of rapid motion of bubbles under water for approximately 50ms or less in high . magnetic fields of 10 T have been carried out successfully for the first time. The observation system constructed is composed of a high-speed video camera, a telescope, a cryostat with a split-type superconducting magnet, a light source, a mirror and a transparent sample cell. Using this system, the influence of magnetic field on the path and shape of single bubbles of $O_2$(paramagnetism) and $N_2$ (diamagnetism) has been examined carefully. Experimental values describing the path are in good agreement with theoretical values calculated on the basis of the magneto-Archimedes effect, despite the effect of magnetism on the bubble. However, no effect of magnetism on the shape of the bubble is observed In addition, the influence of magnetic field on drag coefficient of the bubble is discussed.

• 한국전기전자재료학회논문지
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• 제13권7호
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• pp.630-635
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• 2000

Superconducting power cable is one of the most promising energy application of high-T$\sub$2/ superconductor(HTS). Thus we investigated previously the electrical and mechanical characteristics on Bi-2223 Ag sheathed tape. And a prototype HTS cable have been designed constructed and tested. In case of 19-filament type transport losses agree with the results of norris theory(strip). The critical current of HTS cable(1, 19-filament) in LN$_2$was 116[A], 240[A] and degradation coefficient(k) was 0.71, 0.73 respectively. In case of 19-filament cable critical current was decreased because of mechanical strain at pitch. And AC loss of HTS cable(19-filament) was 0.7 [W/m] in 240[A] loading

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.243-246
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• 2000

The sputtering systems mainly consist of the three-target holder. The target and substrate were the on-axis type. The MgO and STO substrate were used for the deposition of each layer. The optimum conditions of single-layer thin film were investigated from the SEM images and the XRD patterns. Based on the above conditions, the multi-layer thin films such as YBaCuO/LaGaO/Au/Nb and YBaCuO/Au/Nb were fabricated. The crystalline, the electrical Properties, the energy gap structure and the characteristics of the tunneling barrier on the multi-layer thin film have been investigated and characterized.

• 한국초전도ㆍ저온공학회논문지
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• 제20권4호
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• pp.31-35
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• 2018

When REBCO coated conductors (CCs) are applied to superconducting devices such as coils and magnets, they are subjected to deformation in various modes such as compression/tension bending, uniaxial/transverse tension and torsion. Despite outstanding performances by REBCO CC tapes, their electromechanical properties have been evaluated primarily under uniaxial tension, therefore data about the critical current ($I_c$) response in the compressive strain region are lacking. In this study, the characteristic responses of $I_c$ in REBCO CC tapes under bending strains in the range from tensile to compressive were evaluated. The springboard bending beam was used, wherein the CC tape sample was soldered onto the surface of the springboard. A Goldacker-type bending test rig, which lacks a support holding the sample during testing, was used as a comparator. Degradation in $I_c$ behaviors, including strain sensitivity, in differently processed REBCO CC tapes were examined based on the test rig used.