• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.129-132
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• 2003

Yttria stabilized zirconia (YSZ) buffer layers were deposited by a metal organic chemical vapor deposition (MOCVD) technique using single liquid source for the application of YBa$_2$Cu$_3$$O_{7-x}$ (YBCO) coated conductor. Y:Zr mole ratio was 0.2:0.8, and tetrahydrofuran (THF) was used as a solvent. The (100) single crystal MgO substrate was used for searching deposition condition. Bi-axially oriented CeO$_2$ and NiO films were fabricated on {100}〈001〉 Ni substrate by the same method and used as templates. At a constant working pressure of 10 Torr, the deposition temperatures (660~80$0^{\circ}C$) and oxygen flow rates (100~500 sccm) were changed to find the optimum deposition condition. The best (100) oriented YSZ film on MgO was obtained at 74$0^{\circ}C$ and $O_2$ flow rate of 300 sccm. For YSZ buffer layer with this deposition condition on CeO$_2$/Ni template, full width half maximum (FWHM) values of the in-plane and out-of-plane alignments were 10.6$^{\circ}$ and 9.8$^{\circ}$, respectively. The SEM image of YSZ film on CeO$_2$/Ni showed surface morphologies without microcrack.k.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.107-111
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• 1999

A high-temperature superconducting 1.78 GHz bandpass filter, designed for PCS applications, is presented. The structure consists of microstrip pseudo-lumped elements, which make the miniaturization of the filter possible. A 5-pole microstrip filter can be realized on 37 mm ${\times}$ 9 mm LaAlO$_3$ substrate, using double-sided high-temperature superconducting YBa$_2Cu_3O_{7-{\delta}}$ thin film. This filter shows 0.7% fractional bandwidth, 0.3 dB insertion loss, and 12 dB return loss in the passband at 60 K.

• Progress in Superconductivity
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• 제1권1호
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• pp.42-46
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• 1999

A high-temperature superconducting 1.78 GHz bandpass filter, designed for PCS applications, is presented. The structure consists of microstrip pseudo-lumped elements, which enables miniaturization of the filter. A 5-pole microstrip filter could be realized on a 37 mm $\times$ 9 mm $LaAlO_3$ substrate, using double-sided high-temperature superconducting $YBa_2Cu_3O{7-\delta}$ thin film. This filter showed 0.7 % fractional bandwidth, 0.3 dB insertion loss, and 12 dB return loss in the passband at 60 K.

• Progress in Superconductivity
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• 제9권2호
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• pp.188-192
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• 2008

We investigated the size effect on quench development in $Au/YBa_2Cu_3O_7$ (YBCO) thin film meander lines on sapphire substrates. The meander lines were fabricated by patterning YBCO films coated with gold layers. The lines were subjected to simulated AC fault current, and immersed in liquid nitrogen during the experiment. After the initial rapid rise, the resistance increased moderately and then slowly. In 4 inch-diameter meander lines, the period during which the resistance increased moderately was considerably longer than in 2 inch-diameter line. Moderate increase of resistance was originated from quench propagation. The film temperature was about 180 K at the point when the propagation was completed. The rate of resistance increase after the quench completion was not affected by the film size.

• 한국세라믹학회지
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• 제27권3호
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• pp.299-310
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• 1990

The fabrication of Y-Ba-Cu-O films and experimental factors affecting to characteristics of films are studied in detail. Superconducting thick films are fabricated by the screen printing method. The metal-citrate precursors are obtained simply by mixing of metal nitrate with citric acid. The particle size of heat treated powders is approximately 0.3-1${\mu}{\textrm}{m}$ and the thickness of film is estimated as 30-35${\mu}{\textrm}{m}$. According to the XRD analysis, the films sintered at 870-93$0^{\circ}C$ for 10min. -6hr with P(oxygen)=1atm has the unique orthorhombic crystal symmetry indicating the 123 phae. Tc, onset is determined around 92-87。K, but it shows semiconducting behavior probably due to the oxygen deficiency in the lattice, porosity and impurities in films. Extrapolated Tc, zero is estimated as 76-50。K. For films sintered at 90$0^{\circ}C$ for 1hr, superconducting properties are observed with the room temperature resistivity of 0.025$\Omega$.cm Tc, onset at 88。K and Tc, zero at 63。K.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2003년도 High Temperature Superconductivity Vol.XIII
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• pp.70-70
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• 2003

• 대한화학회지
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• 제36권1호
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• pp.16-23
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• 1992

고온초전도체 $YBa_2Cu_3O_{7-{\delta}}$에서 Y를 Eu로 치환시킨 $(Y_{1-x}Eu_x)Ba_2Cu_3O_{7-{\delta}}$ (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0)를 제조한 후 물성변화를 관찰하였다. X-선 회절분석결과 모든 시료가 사방정계 구조를 갖고 있었으며 x값이 증가함에 따라 격자상수 a, b 및 c도 증가하였다. 전기저항과 자화율측정으로부터 순수한 90K 이상의 고온초전도상이 생성되었음을 알았으며, x값이 커짐에 따라 임계온도가 상승하였다. 주사전자현미경을 사용하여 구한 낟알크기와 자화측정결과로부터 각각의 시료들에 대한 부피 반자성자화율을 구하였으며, x값이 커질수록 이 값은 감소하였다. Eu의 농도가 증가함에 따라 결정격자내의 Ba의 양이 감소됨을 EPMA로 확인하였으며, 이것은 부피반자성 자화율의 감소에 직접적인 영향을 주는 것으로 판단된다.

• Progress in Superconductivity
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• 제5권1호
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• pp.84-87
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• 2003

$YBa_2$$Cu_3$$O_{7-x}$ (YBCO) thin films were fabricated by MOD-TFA process via dip-coating method on LaAlO$_3$, (LAO) single crystalline substrates. In this study, we investigated effect of annealing temperature and solvent on the microstructure and texture of YBCO thin films. The precursor films were annealed at various temperature to improve surface morphologies and phase purities. It was shown that the films annealed at relatively lower and higher temperature exhibit low phase purity and crystallinity. The effect of various solvents on surface morphologies and second phase has been investigated.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.161-164
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• 1999

We have fabricated the direct-coupled planar type 1st-order SQUID gradiometers. The gradiometer consists of moats or slots in SQUID loop. It is made by YBa$_2Cu_3O_7$ thin films using pulsed laser deposition method on SrTiO$_3$ single crystal and bi-crystal substrates. We have studied the effects of slots and moats in SQUID loop by measuring the voltage modulation signals under uniform field and 1st-order gradient, and the noise properties under non-shielded environment.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2007년도 High Temperature Superconductivity Vol.XVII
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• pp.94-94
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• 2007