• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.34-37
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• 1999

We have fabricated YBCO/STO/YBCO multilayer by the pulsed laser deposition method varing the deposition condition of insulating STO layer. Superconducting properties of both YBCO layers are sensitively affected by the deposition condition of STO layer. We obtained the upper YBCO layer of T$_{c(zero)}\;{\sim}\;$90 K with a good reproducibility, however, T$_{c(zero)}$ of lower YBCO layer was decreased to about 80 K maybe due to the oxygen loss during the deposition of STO layer. Superconducting properties of both YBCO layers at every fabrication step were measured in order to study the reason for the deterioration of superconducting properties.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.268-268
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• 2006

YBCO 초전도 박막을 제조하기 위해 일반적으로 사용되는 RABiTS공정을 통해 제조된 양축 정렬된 Ni 선재 위에 직접 YBCO를 증착시키려는 시도가 많이 이루어졌다. Ni 위에 직접 증착시킨 YBCO 박막은 c-축으로 정렬되는 온도에서 Ni이 확산되어 YBCO와 반응하여 초전도 물성을 약화시킨다. 이것을 방지하기 위하여 완층층을 먼저 증착을 하는 연구를 시행하였다. 본 연구는 Ni-5at.%W(100) 기판위에 hot-wall type MOCVD (metal organic chemical vapor deposition)를 이용하여 증착을 실시하였다. 완층층으로는 Ni, YBCO와 각각 4.70%, 3.32%의 lattice mismatch를 갖는 $Yb_2O_3$를 선택하였으며, 증착 조건으로는 온도 $800\;{\sim}\;1000^{\circ}C$, 시간 3 ~ 10min, 증착압력 10 Torr의 조건에서 증착을 행하였다. $Yb_2O_3$를 형성하기 위해 산소를 이용하였으나 $Yb_2O_3$(200) 형성을 방해하는 NiO(111)이 형성되었다. 산소를 대신해 수증기를 이용하여 NiO 상이 없는 $Yb_2O_3$(200)을 형성하였다. 증착 시간과 수증기 압력에 따른 $Yb_2O_3$의 $I_{(200)}/(I_{(111)}+I_{(200)})$의 상대 회절강도비를 XRD (X-ray diffraction)를 이용하였고, 증착된 표면 형상은 SEM(scanning electron microscopy)을 통해 관찰하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.211-211
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• 2009

YBCO coated conductor can change the stabilization layer for purpose and it leads advantages in Improvement of tape's critical properties and Application. Such properties rise possibility of using YBCO coated conductor for Superconductor Fault Current Limiter, therefore, we investigate changing properties under over current condition and limiting characteristics. In this study, YBCO coated conductor's current limiting characteristic stainless steel stabilization layer under condition of changing conductor's insulating layer. Consequently, the resistance followed insulating layer so we know that limiting characteristics.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.365-367
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• 2002

A serious problem in using YBCO films for fault current limiter is inhomogeneities caused by imperpect manufacturing. So simultaneous quenches are a difficult problem which elements for current limiting are connected in series for increasing voltage ratings. We investigated extended electric field - current characteristics for current limiting element of YBCO film when 0-130mT magnetic field is applied. And quench characteristics were investigated in over all element and between elements of YBCO films. From the experiments, it was shown that applied magnetic fields using solenoid coil induced uniform quench distribution for over all stripes and simultaneous quench in all elements for current limiting of YBCO film was realized.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.80-84
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• 2000

High temperature superconductor shows a good electric and magnetic properties and is known as a good candidate in various electronic device application. At present the technique to construct multilayers composed of HTS films and insulator films has not been fully studied in domestic research institutes. Since the construction of any reasonable eletronic devices require the use of multilayers, the development of HTS eletronic devices has been limited. To manufacture multiplayer, several processing steps which involve deposition and ion millings are required. To manufacture a good quality multilayerd structure, not only the deposition techniques but also the proper patterning have to be developed. In this work, we have fabricated a YBCO/STO/YBCO multiplayer and studied the electronic properties of it.

• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.84-88
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• 2002

The resistive fault current limiter (SFCL) is a very attractive device for power networks. But it has a serious Problem in using YBCO films for fault current limiter is inhomogeneities caused by imperpect manufacturing. So simultaneous quenches are a difficult problem which elements for current limiting are connected in series for increasing voltage ratings. We investigated extended electric field-current characteristics for current limiting element of YBCO film when O-130mT magnetic field is applied. And quench characteristics were investigated in over all element and between elements of YBCO films. From the experiments, it was shown that applied magnetic fields using solenoid coil induced uniform quench distribution for over all stripes and simultaneous quench in all elements for current limiting of YBCO film was realized. We have achieved resistive fault current limiter of 1.2kV/20A rating using magnetic field.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.27-29
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• 2003

Solution-based MOD-TFA deposition technology of YBCO layers offers a route to low-cost YBCO coated conductors. Since the structures and properties of grown thin film by MOD process are strongly influenced by chemistry of precursor solution, the chemical modification of precursor solution for MOD process are important for improvement of the electrical properties of YBCO films. In this study, the precursor solution for MOD process are modified by chemical additives and solvents. The microstructure and texture of YBCO films grown by chemically modified precursor solution were characterized with SEM/EDS, XRD.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.79-82
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• 2003

We prepared YBCO coated conductor by direct deposition of YBCO on Ag substrate by a MOCVD method. The Ag substrate was only prepared by cold rolling. The XRD data of the as-rolled Ag tape showed the formation of dominant (420) oriented grains. Processing variables were the oxygen partial pressure (Po$_2$) and deposition temperature (T$_{d}$). It was found that the a-axis oriented films were grown at lower T$_{d}$ below 80$0^{\circ}C$, while the c-axis oriented films were grown about 80$0^{\circ}C$. The surface of the films consisted of a second inclusion phase dispersed in the YBCO matrix. The Cu-rich phase regions were observed at the YBCO/Ag interface probably due to the inter-diffusion of Ag and Cu. Cu.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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• pp.56-60
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• 2000

Cube texture를 갖는 Ni기판위에 MOCVD(Metal Chemical Vapor Deposition)를 이용하여 NiO, CeO$_2$, YBCO 박막을 제조하였다. NiO(200)와 CeO$_2$(200) buffer layer는 450${\sim}$470$^{\circ}$C에서 10분간 MOCVD방법으로 (100)<001>Ni 기판위에 직접 증착하였다. 제조된 NiO, CeO$_2$ buffer layer는 조직이 치밀하며 표면의 상태가 매우 좋으며 Ni기판 위에 epitaxial하게 성장하였다. NiO는 Ni기판과 NiO<100>//Ni<100>의 방위관계를 가지고 성장하였으며, CeO$_2$는 증착조건에 따라 CeO$_2$ <100>//Ni<100> 및 CeO$_2$ <110>//Ni<100> 의 방위관계를 가지고 성장하였다. 증착된 NiO막과 CeO$_2$막에서 균열은 발생하지 않았다. MOCVD법으로 표면에 biaxial texture를 갖는 ceramic buffer를 증착시킨 NiO/Ni및 CeO$_2$/Ni 기판위에 YBCO박막을 MOCVD법으로 제조하였다. YBCO막은 기판온도 800$^{\circ}$C,증착압력 10torr, 산소분압을 0.7torr로 하여 10분간 행하였다. 공급원료의 조성에 따라 YBCO의 막의 texture와 형성되는 상이 변화되었다. NiO/Ni및 CeO$_2$/Ni 기판 위에 증착된 YBCO막은 c축 배향성을 가지고 성장하였으며, -scan 및 ${\varphi}$ -scan으로 측정한 (500)면의 in-plane과 (110)면의 out-of-plane의 FWHM(Full Width Half Maximum)값은 각각 10$^{\circ}$ 미만으로 우수하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.246-247
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• 2007

최근 KEPRI-LSIS가 공동 개발한 하이브리드형 초전도 한류기 동작 시, 사고 검출을 담당하는 초전도체의 최적 설계에 적용하기 위하여 Au/YBCO 박막의 ��치 회복 특성을 조사하였다. $600\;V_{rms}$, 3 ms의 사고가 초전도 박막에 인가되었을 때, ��치가 종료된 이후 초전도성을 회복하기 위해 142 ms의 시간이 소요되었다. 또한 인가 시간이 증가함에 따라 소요 시간도 비례하여 증가하여 4 ms 동안 인가되었을 때, ��치 회복 시간은 272 ms로 측정되었다.