• 한국전기전자재료학회논문지
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• 제35권6호
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• pp.622-625
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• 2022

YBa₂Cu₃O_7-y bulk as a high temperature oxide superconducting conductor has the high critical temperature of 92 K. YBa₂Cu₃O_7-y bulk superconductors have been fabricated by a seeded melting growth. Magnetic properties were studied by using superconductor of melted YBa₂Cu₃O_7-y oxides. It was demonstrated that Y₂BaCuO₅ particles acts as a pinning center which plays an important role on the magnetic properties. The thickness of the upper and lower pellets of the YBa₂Cu₃O_7-y bulk was formed at 40 mm with 55 g of the composition, and the YBa₂Cu₃O_7-y superconductor was manufactured through a heat treatment process. Manufacturing the superconducting bulk, it is possible to improve the pore density of the superconducting bulk by providing a path through which oxygen could be emitted.

• 한국세라믹학회지
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• 제27권3호
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• pp.355-360
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• 1990

One of the possible ways to make a flexible wire of high-Tc superconductiong ceramics is the extrusion of a mixture slurry of superconducting powder with an appropriate polymer binder. The fabrication procedure for $YBa_2Cu_3O_{7-{\delta}}$ superconducting coils with this plastic mass is described. The major factors limiting the formation of extruded wire are the binder content, powder size, and entrapped gas in the mixture slurries. The optimum content of binder for both good flexbility and strength of wire was estimated to be 30wt%. The finer the powder size is, the more homogeneous structure the extruded wire has. The vacuum degassing before extrusion was necessary to remove the entrapped gas in as-extruded wire. The formability of wire depends greatly on the wire radius and binder content. After burning out the binder and the successive sintering, the contacts between the superconducting grains could be made. The resistivity vs. temperature behavior measured in the final wire showed the transition temperature of 90K with narrow transition width. However, the critical current densities of these wires are much lower in comparison to those of conventional bulk specimens.

• 한국산학기술학회논문지
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• 제19권3호
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• pp.69-74
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• 2018

산업현장에서 사용되는 대형 모터는 전기자권선의 절연내력 저하 및 과열문제 등으로 인하여 정지사고의 위험이 높고 산업재해의 규모가 크므로 넓은 장소의 확보가 필요하다. 따라서 기존 모터에 비해 소형, 경량이면서 절연내력이 뛰어난 대용량 모터가 요구되어지고 있으며 이에 대한 연구가 활발히 진행되어지고 있다. 초전도 모터는 기존의 발전기나 모터와 같은 회전기의 계자코일을 초전도 화하여 계자의 발생을 크게 증가시킴으로서, 기기의 효율과 출력을 높이고, 소형화 및 경량화, 안정도 향상 등의 장점을 가지고 있으므로 초전도 선재의 성능을 발휘할 수 있도록 선제의 임계온도 이하로 낮추어줄 수 있는 냉각시스템의 설계 및 해석기술이 매우 중요하다. 따라서 본 연구에서는 100HP 고온초전도 동기모터의 개념설계를 통한 계자손실 해석과 냉각시스템의 저온 열전달 해석을 수행하였다. 계자손실 해석 결과, 고온초전도 선재를 사용하게 되면 균일한 공극자속밀도가 나타남을 확인하였다. 그리고 가스네온 및 액체네온에 대한 저온 열전달 해석 결과, 고온초전도 선재의 저온 안정성을 유지하기 위해서는 액체네온 1kg/min의 유량의 사용이 적합함을 확인하였다.

• 한국전기전자재료학회논문지
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• 제22권7호
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• pp.606-611
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• 2009

AC loss is one of the important factors for commercialization of a high temperature superconducting (HTS) cable from an economic point of view. But AC loss characteristics of the HTS-cable are not elucidated completely because of its complex structure. As an earlier stage of analyzing the AC loss in the 22.9 kV/50 MVA, 100m HTS-cable system of Korea Electric Power Corporation (KEPCO) which is now in collaboration with us, a two-dimensional (2D) numerical model, which takes into account the nonlinear conductivity properties of a high temperature superconductor, has been developed. In order to examine our 2D model, we have prepared several single-layer cable samples whose AC losses are sufficiently reliable due to their simple structure. The AC losses of the samples were experimentally investigated and then compared with our 2D model. The results show that the numerically calculated AC losses are not in good agreement with the measured ones for the cylindrical cable and deca-cable samples with low critical current density. However, the numerically calculated and measured AC losses are relatively in good agreement for the deca-cable and hex-cable samples with high critical current density, although the difference between these two loss data in the deca-cable sample tends to increase in the low current region.

• 한국재료학회지
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• 제9권8호
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• pp.849-853
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• 1999

본 연구에서는 액상성장법(LPE법)으로 $Bi_2$-x(sub)$LSr_2$Ca(sub)1+x(sub)$LCu_2$O(sub)8+d (x(sub)L=0, 0.05, 0.1, 0.2) 막(film)을 작성하여 초전도특성을 알아보았고, XPS 측정으로 얻은 Sr3d과 Ca2p의 피크분해 결과와 EPMA 측정 결과를 통하여 각 layer에 있어서 원자들의 분포상태에 관하여 조사하였다. 작성한 막(film)의 c-축의 길이는 x(sub)L(융해조성비)의 증가에 따라 단조로이 증가하였고, 임계온도 T(sub)c는 x(sub)L=0.1 부근에서 최고치를 나타내고 있었다. x(sub)L의 변화에 따른 임계온도 T(sub)c와 c-축의 길이의 변화는 BiO-layer에 있는 과잉산소의 변화에 의한 것이며, SrO-layer에서 원소들의 분포상태와 결손이 초전도특성 및 결정구조에 영향을 미치고 있음을 알 수 있었다.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2586-2591
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• 2022

In the present work, we have irradiated the DI-BSCCO superconducting tapes with the 100 keV deuterium ions to investigate the effect of ion irradiation on their critical current (Ic). The damage simulations are carried out using the binary collision approximation method to get the spatial distribution and depth profile of the damage events in the high temperature superconducting (HTS) tape. The point defects are formed near the surface of the HTS tape. These point defects change the vortex profile in the superconducting tape. Due to the long-range interaction of vortices with each other, the Ic of the tape degrades at the 77 K and self magnetic field. The radiation dose of 2.90 MGy degrades the 44% critical current of the tape. The results of the displacement per atom (dpa) and dose deposited by the deuterium ions are used to fit an empirical relation for predicting the degradation of the Ic of the tape. We include the dpa, dose and columnar defect terms produced by the incident particles in the empirical relation. The fitted empirical relation predicts that light ion irradiation degrades the Ic in the DI-BSCCO tape at the self field. This empirical relation can also be used in neutron irradiation to predict the lifetime of the DI-BSCCO tape. The change in the Ic of the DI-BSCCO tape due to deuterium irradiation is compared with the other second-generation HTS tape irradiated with energetic radiation.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.315-317
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• 2002

The value of I$_{c}$(critical current) in HTS (High Temperature Superconducting) tape has a great influence on B(equation omitted) (magnetic field amplitude applied perpendicular to the tape surface). Therefore, I$_{c}$ of HTS magnet is determined by not only operating temperature but also the B(equation omitted). In shape design of field coil for the HTS motor, a method to reduce the B(equation omitted) and to determine operating current should be considered in order to optimal design. On the basis of the magnetic field analysis, this paper deals with various field coil shape to obtain operating current of HTS motor by using analytical method. And also this paper discusses the operating current of 100hp class HTS motor by using I$_{c}$-B(equation omitted) curve.curve.

• 한국초전도ㆍ저온공학회논문지
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• 제19권2호
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• pp.1-8
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• 2017

Recently, Research and development activity of HTS (High Temperature Superconducting) power application is very progressive worldwide. Especially, HTS cable system and HTSFCL (HTS Fault current limiter) system are proceeding to practical stages. In such system and equipment, cryogenic cooling system, which makes HTS equipment cooled lower than critical temperature, is one of crucial components. In this article, cryogenic cooling system for HTS application, mainly cable, is reviewed. Cryogenic cooling system can be categorized into conduction cooling system and immersion cooling system. In practical HTS power application area, immersion cooling system with sub-cooled liquid nitrogen is preferred. The immersion cooling system is besides grouped into open cycle system and closed cycle system. Turbo-Brayton refrigerator is a key component for closed cycle system. Those two cooling systems are focused in this article. And, each design and component of the cooling system is explained.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.41-44
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• 2000

The mixed-state Hall angle has been measured in Hg-based superconducting thin films as functions of magnetic fields (H) up to 18 T. The temperature dependence of the Hall angle shows a peak (T$^{\ast}$) at low temperature, which is consistent with a crossover point from the thermally activated flux flow (TAFF) to a critical region (CR). At low fields below 10 T, T$^{\ast}$ shifts to low temperature with increasing fields. Interestingly, however, we found that T$^{\ast}$ is independent of fields above 10 T, suggesting unusual vortex state. A physical implication of H - T$^{\ast}$ line will be discussed.

• Progress in Superconductivity
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• 제2권1호
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• pp.39-42
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• 2000

The mixed-state Hall angle has been measured in Hg-based superconducting thin films as functions of magnetic fields (H) up to 18 T. The temperature dependence of the Hall angle shows a peak (T*) at low temperature, which is consistent with a crossover point from the thermally activated flux flow (TAFF) to a critical region (CR). At low fields below 10 T, T* shifts to low temperature with increasing fields. Interestingly, however, we found that T* is independent of fields above 10 T, suggesting unusual vortex state. A physical implication of H-T* line will be discussed.