• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.810-813
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• 2000

In this study, we fabricated Bi-2223/Ag high temperature superconducting tapes using PIT (Powder-In-Tube) process to apply the superconducting magnet, cable and etc. It's inevitable to deform the superconducting tapes with axial strain for application. Therefore, for the characterization of the strain sensitivity of the superconducting properties, the degradation of Bi-2223/Ag tapes due to axial strain were investigated by measuring the critical current as a function of applied tension strain and external magnetic field. The critical current of Bi-2223/Ag tapes were decreased slightly up to 0.3∼0.4% applied strain but, drastically decreased more than these strains. Superconducting filament cores consisted of brittle ceramic fibers were broken easily by the large strain and current path were decreased simultaneously.

• Progress in Superconductivity
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• v.3 no.2
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• pp.247-251
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• 2002

In general, the bubbling, generated during the fabrication of the tapes, breaks the superconducting filament, and critical current of the tapes will be decreased. Heat-treatment schemes of Bi-2223/Ag HTS tapes were modified, such as pre-annealing of multi-stacked billet, 2-step main sintering and ramp rate etc. The generation of bubbling was drastically decreased from 20 bubbles/m to 0 ~ 1 bubble/m by the modified heat-treatment. Therefore, the value of critical current of the tapes without bubbling was increased almost twice higher than that of already existing tapes. Critical current up to 42 A in 40 m length Bi-22231Ag tapes have been measured at 77K, self-field, 1$mutextrm{V}$/cm criterion. It could be confirmed that elimination of bubbling is effective to maintain the superconducting property along the tape length.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.295-299
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• 1996

In order to investigate the relation between the microstructure and the V-I characteristics of HTSC wire, single and 19 filamentary silver-sheathed Bi2223 tapes were fabricated using the powder-in-tube method. Higher J$\_$c/ at 77.3 K(0 T) and 4.2 K(in magnetic field) can be achieved for the 19 filamentary Bi tape, comparing the single filamentary tape. However, the I$\_$c/ distribution of 19 filamentary Bi2223 tape was found to be wider by analyzing the curve obtained from 2nd differential of V-I data. This was considered to be resulted from worse uniformity of oxide filament due to severe cold working.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.17-20
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• 2002

The effects of relatively low lead content (0.2~0.3) on the 2223 phase formation and transport property of Bi-2223/Ag tapes have been investigated. The results show that lead contents have great impact on the phase assemblage of precursors, subsequently, on the phase formation and transport property of silver sheathed BSCCO-2223 tapes. Powders containing Pb=0.25 and Pb=0.3 resulted in the nearly identical $J_c$ values in fully processed tapes, but leaded to significant difference on the phase formation process. For the case of Pb=0.2, both low conversion fraction of 2212 to 2223 and low $J_c$ value were obtained in final reacted tape, which was probably due to lack of enough liquid phase to facilitate the phase transformation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.10
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• pp.554-559
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• 2002

The at loss is an important issue in the design of superconducting cables and transformers. In these devices the Bi-2222 tapes are usually placed face-to-face. In such arrangements ac loss is influenced by adjacent tapes. The effect is investigated by measuring the magnetization loss in the stacked conductor, which consists of various numbers of Bi-2223 tapes. For the single tape the magnetization loss in perpendicular field is larger than that in parallel field by about a factor 10. This agrees well with the prediction for hysteresis loss in slab and strip models. For the stacked conductor in perpendicular field the magnetization loss at low fields is greatly decreased, compared to the loss of the single tape. However the loss at high fields is nearly unaffected. This behavior is well described by the slab model.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.101-103
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• 2000

In the present work, we have investigated the combined effect of high-energy milling and Agb addition on microstructure and superconducting properties for Bi-2223/Ag. tape. The addition of siver plays an important role in enhancing liquid phase formation, Resulting in densification and cracking during solidification. Further study is needed for the optimization of Ag content and heat-treatment which can reduce the cracking.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.789-791
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• 2003

다수본의 Bi-2223테이프로 구성되는 도체의 자기자계손실에 대한 검토를 하였으며, 그 주요 결과를 보면 자기자계손실은 도체를 구성하는 테이프의 임계 전류밀도가 커짐에 따라서 증가한다. 또한 테이프의 코아가 전자기적으로 분리되어 있는 경우 도체의 자기자계 손실은 테이프의 임계전류에 무관한 반면 결합되어 있는 경우는 테이프의 임계전류가 커짐에 따라서 도체의 자기자계손실도 증가할 것으로 예상된다.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.786-788
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• 2003

Bi-2223테이프의 동저항 및 동저항손실에 대해 조사하였으며, 그 주요 결과는 외부교류자장이 어느 정도 큰 경우에 한해서는 테이프의 동저항은 전류에는 의존하지 않고, 자장 및 주파수에는 비례한다. 또한 동저항손실은 전류가 증가함에 따라서 급격히 증가하며, 외부교류자장에 비례하고, 주파수에는 거의 의존하지 않는다.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.854-856
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• 2002

필라멘트의 트위스트피치가 Bi-2223테이프의 통전손실에 미치는 영향에 대해 실험적으로 조사하였으며, 그 주요 결과는 Bi-2223테이프의 자기자계손실은 필라멘트의 트위스트피치에 의해서는 그다지 영향을 받지 않는 반면 외부교류자장 하에서 Bi-2223테이프에 발생되는 통전손실은 트위스트피치에 영향을 비교적 크게 받으며, 필라멘트의 트위스트피치가 작을수록 통전손실도 작아진다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.50-54
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• 2002

Influences of bending strain on the critical current ($I_c$) in Ag-sheathed Bi-2223 superconducting tapes at 77K were investigated. The effect of bending mode on the bending strain characteristics was discussed in viewpoints of sample geometry, n-value and damage morphology. Especially, in this paper, we reported the $I_c$ behavior in Ag alloy sheathed Bi-2223 multifilamentary superconducting tapes under hard bending. As a result, $I_c$ degradation behavior of the hard bending appeared remarkably than the case of easy bending, but it did not influence greatly on the n-value.