• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.137-139
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• 2003

The relationship between magnetic properties of BiPbSrCaCuO superconductor and externally applied magnetic field was studied to develop a magnetic field polarity sensor. The behavior was related to the magnetic flux trapped in the superconductor, which penetrates through the material by the external magnetic field. Some portion of the superconductor was changed to a normal state by the trapped magnetic flux. Electrical characteristics of the superconductor with trapped magnetic flux were extremely sensitive to the external magnetic field and showed different responses depending on the direction of the magnetic field.

• Progress in Superconductivity
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• v.3 no.2
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• pp.188-192
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• 2002

To introduce flux pinning center in HTS-BSCCO system, nano-size MgO particles were uniformly distributed within the Bi-2223 grain by partial hydration of MgO. The existing method MgO doped Bi-2223 used nato-size MgO powders, which resulted in agglomeration during mixing or grain growth during heat-treatment due to the high surface energy of the fine particles. By hydration of the MgO surface, the agglomeration of the MgO powders was avoided and the size of remaining MgO core was controlled by changing hydration medium and time. The thin film obtained by spin coating of (Bi_$1.8/Pb_{0.4}$)$Sr_2$$_{Ca}$$2.2/Cu_3$ $O_{y}$ nitrate solution mixed with hydrated MgO showed the even distribution of nano-size MgO particles in the Bi-2212 grains.s.s.

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.115-122
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• 1997

The powder preparation by using emulsion drying method, one of the chemical powder fabrication methods has the advantages; easy to control the chemical stoichiometry and to fabricate homogeneously fine particles. In the present study, the initial morphology and size distribution of the powder fabricated by using emulsion dry-ing method were controlled and were improved the homogeneity. By carefully controlling the mixing ratio of oil phase and aqueous solution and surfactant of preventing emulsion separation, the Bi(Pb)-Sr-Ca-Cu-O su-perconducting powders were prepared. The properties of the superconducting powder fabricated by this method and the microstructures and superconducting properties of the pelletized samples were investigated. The microstructures and electric properties of the tapes prepared by oxide powder-in-tube method were in-vestigated. The fabricated powder was spherical with less than 1$\mu$m but most of them was agglomerated with 2~5$\mu$m in size. The critical temperature of the pelletized sample annealed at 84$0^{\circ}C$ for 72 hours in oxygen par-tial pressure of 1/13atm in Ar atmosphere was 108K. And the critical current of the first and second annealed tapes in air prepared by oxide powder-in-tube process were 0.4A and 1.5A, respectively.

• Progress in Superconductivity
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• v.4 no.1
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• pp.90-93
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• 2002

The sintering process of BSCCO 2223 tapes is a complex process that is very sensitive to parameters, such as temperature, oxygen partial pressure, heating and cooling rate and holding time. During the first heat treatment, 2212 phase of precursor powder is partially transformed into 2223 phase and some residual secondary phases, such as $(Bi,Pb)_2$$Sr_2$CuO／sub y／(2201), $(Ca,Sr)_2$CuO／sub y／(2/1AEC), (Ca,Sr)／sub 14／Cu／sub 24／O／sub 41／(14／24 AEC) etc. The secondary phases are difficult to be removed from the BSCCO 2223 matrix on the heat treatment. These secondary phases degrade the critical current density. In order to minimize the amount and size of alkaline earth cuprate(AEC) particles step heat treatment is applied during the first heat treatment under the varying atmosphere. Experimental results showed that by adapting the step heat treatment process, the amount and particle size of the secondary phases in the final tapes are decreased. Consequently, the BSCCO 2223grain texture and Jc properties are improved.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.11
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• pp.1014-1021
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• 1998

We evaluated the effect of processing variables on microstructural evolution interface irregularity between Ag sheath and superconductor core and resultant critical current density(J$_{c}$) of (Bi,Pb)$_2$Sr$_2$Ca$_2$Cu$_3$O$_{x}$(2223) superconductor tape. The value of J$_{c}$ was significantly influenced by the interface irregularity, degree of texturing and relative 2223 content. The interface became more irregular(sausage effect), while the degree of texturing gradually improved as the dimension of tape decreased during forming process. As the dimension of wire/tape were changed from diameter of 3.25 mm to thickness of 0.20 mm, J$_{c}$ value was observed to be increased by 10 times. In addition, optimum sintering temperature for improved J$_{c}$ was observed to be 835$^{\circ}C$ in a ambient atmosphere probably due to combined effect of both improved texturing and high 2223 content. Microstructural investigation showed the degree of texturing was degraded by the existence of both second phases and interface irregularity. It was observed that larger grain size and better texturing was developed near relatively flat interface compared to those inside superconducting core.ting core.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.535-537
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• 2009

As a kind of high Tc superconductor application technique, a study on the development of energy storage device system using BiPbSrCaCuO superconductor was performed. Chemical melt process was developed to gabricate the high magnetization superconductor which is needed to develop the energy saving system and the effect of various process variable on the superconducting properties of the specimens were tested and analyzed. Magnetochemical interactions between superconductor and permanent magnet was also experimented.

• 한국초전도학회:학술대회논문집
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• v.12
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• pp.60-60
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• 2002

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.252-255
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• 1996

Superconducting current lead is one of the promising applications of the oxide high-Tc superconductors, because they have the advantage of decreasing heat conduction to low temperature region, comparing with a conventional cooper alloy lead. High critical current density is a key factor for the applications such as current lead. (Bi,Pb)$_2$Sr$_2$Ca$_2$Cu$_3$O$\_$x/ high Tc superconductor haute been investigated in terms of critical current density. Bi-2223 superconducting current lead made by CIP and solid state sintering process. Bi-2223 current lead that heat treated at 836$^{\circ}C$ for 240 h in 1/13 P$\_$O$_2$/ had over 150 A/$\textrm{cm}^2$ of critical current density at 77K. We knew that the superconducting properties of tube type current leads were better than rods type of them. And we investigated the relation of Bi-2223 formation and heat treatment condition by XRD and SEM analysis.

• Economic and Environmental Geology
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• v.46 no.2
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• pp.199-206
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• 2013

The Daehyun gold-silver deposit consists of two hydrothermal quartz veins that fill NE-trending fractures in the Cambro-Ordovician calcitic marble. I have sampled wallrock, hydrothermaly-altered rock and gold-silver ore vein to study the element dispersion and element gain/loss during wallrock alteration. The hydrothermal alteration doesn't remarkably recognized at this deposit and consists of mainly calcite, dolomite, quartz and minor epidote. The ore minerals composed of arsenopyrite, pyrrhotite, pyrite, sphalerite, stannite, chalcopyrite, galena, electrum, native bismuth and silver-bearing mineral. Based on analyzed data, the chemical composition of wallrock consists of mainly $SiO_2$, CaO, $CO_2$ with amounts of $Al_2O_3$, $Fe_2O_3(T)$ and MgO. The contents of $SiO_2$, $Fe_2O_3(T)$, MgO, CaO and $CO_2$ vary significantly with distance from ore vein. The element dispersion doesn't remarkably recognized during wallrock alteration and only occurs near the ore vein margin because of physical and chemical properties of wallrock. Remarkable gain elements during wallrock alteration are $Fe_2O_3(T)$, total S, Ag, As, Bi, Cd, Cu, Ni, Pb, Sb, Sn, W and Zn. Remarkable loss elements are $SiO_2$, MnO, MgO, CaO. $CO_2$ and Sr. Therefore, Our result may be used when geochemical exploration carry out at deposits hosted calcitic marble in the Hwanggangri metallogenic district.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.10-13
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• 1999

For large scale applications of high temperature superconductor(HTS) such as transmission cables, motors and generators, long length of flexible HTS conductors is required. Currently, HTS tape that is capable of being fabricated in long length by industrial processes is the Bi-2223 HTS tape. In this study, we fabricated 19 filamentary Bi-2223($Bi_{1.8}$$Pb_{0.4}$$Sr_{2}$$Ca_{2}$$Cu_{3}$$O_{10+X}$) HTS tape with 100m length by PIT(Powder In Tube) process. Critical current(Ic) of this long length tape was measured 18.5 A at 77 K, self field and short sample Ic is 32.5 A at the same condition. Critical current of 100m length tape was decreased by about 1/3 compared to that of short tape. This was mainly resulted from the increase of non homogeneity in oxide layer.