• Proceedings of the Materials Research Society of Korea Conference
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• 1997.05a
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• pp.43-43
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• 1997

• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.811-815
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• 1997

The present work describes the effect of dry grinding of a mixture composed of $Y_2O_3$, $BaCO_3$ and CuO powders with a planetary ball mill before heat treatment on crystal structure and superconductivity in the $YBa_2Cu_3O_{7-y}$. The specific surface area of the ground product of mixture decreased with an increase in the grinding time, after showing an upward trend up to 60 minutes of grinding. The critical current density, which was influenced by the grinding time of mixture, indicates the maximum value of about $150A/cm^2$ in the case of 60 minutes grinding, while the critical temperature, which were around 90K, for the sintered bodies were almost independent of the grinding time.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.4
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• pp.210-218
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• 2000

For the fabrication of $YBa_2Cu_3O_x$ thick film, a substrate of $Y_2BaCuO_5$ was fabricated by adding $CeO_2$ into $Y_2BaCuO_5$ and two types of doping materials added with binder material were prepared. Each doping material was patterned on $Y_2BaCuO_5$substrate by the screen printing method and then was annealed at the temperature with a few step. It could be observed by X-ray diffraction patterns and SEM photographs that through the diffusion process of the $Y_2BaCuO_5$ and each doping material, the $YBa_2Cu_3O_x$ phase was formed. And with n additive of $CeO_2$ the thickness of formed $YBa_2Cu_3O_x$decreased. From the experiment of current limiting on thick film, the sample with thiner thickness of $YBa_2Cu_3O_x$ showed the more effective characteristics of current limiting.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.247-250
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• 1999

We have performed $^{63,65}$Cu nuclear quadrupole resonance (NQR) measurements on Zn and Ni doped YBa$_2Cu_3O_7$ (YBa$_2Cu_{3-x}M_xO_7$, M=Zn or Ni, x = 0.00 ${\sim}$ 0.09). Doping effects are markedly different in relaxation rates as well as in superconducting transition temperatures. Both the spin-lattice and the spin-spin relaxation rates decrease for Zn doped YBCO. However, those increase for Ni doped YBCO. This contrast in local electronic dynamics provides a clear microscopic evidence that Zn forms no local moment, while Ni develops a local moment. Consequently, the antiferromagnetic spin fluctuation is suppressed by Zn doping whereas it is preserved by Ni doping.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.229-237
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• 1996

The superconducting phase, $YBa_{2}Cu_{3}O_{x}$ (YBCO), was in-situ deposited on the single crystal MgO substrates, using an aerosol decomposition process in a cold plasma reactor. The solubility and decomposition temperature of the chemical precursors, and the vapor pressures of the solvents, were determined to be the factors crucial to achieving a stoichiometric, crystalline YBCO phase. The deposition parameters for the YBCO phase were 0.3 to 2.7 kPa for the oxygen partial pressure and $800^{\circ}C$ to $940^{\circ}C$ for the substrate temperature. The optimum deposition conditions for the YBCO phase were observed along the CuO decomposition line.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.179-183
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• 2000

For a ground plane in high-temperature superconducting ramp-edge junction devices, YBa$_2$Cu$_3$O$_{7-{\delta}}$/SrTiO$_3$/YBa$_2$Cu$_3$O$_{7-{\delta}}$ multilayer structures were fabricated using pulsed laser deposition and ECR ion milling. Various process parameters were adjusted to enhance the device characteristics. By etching the STO layer to form a tapered edge of about 15$^{\circ}$ and in-situ RF plasma treatment of bottom YBCO surface prior to deposition of top YBCO, the top-to-bottom YBCO showed T$_c$ of 75${\sim}$80 K and I$_c$ of about 40 mA through holes. It was found that the deposition of bottom YBCO at a reduced laser repetition rate of 1Hz increased the T$_c$ of top YBCO to 79.9 K. The resistivity of 570 layer was about 10$^6$ ${\Omega}$cm at 60 K, which ensures good electrical isolation between successive YBCO layers.

• Progress in Superconductivity
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• v.2 no.1
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• pp.43-46
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• 2000

We report on the tunneling spectroscopy of tunnel junctions using d-wave superconductor in relation to Andreev reflection. The zero bias conductance peak (ZBCP) which has maximum on [110] direction of ab-plane is observed on metal $Au/YBa_2Cu_3O_y$ tunnel junctions while it is suppressed on the ferromagnetic $Co/Au/YBa_2Cu_3O_y$ tunnel junctions. The effects of Andreev reflection on the differential conductance of each junction are dependent on the tunnel direction. For the $Co/Au/YBa_2Cu_3O_y$ junction, the suppression of Andreev reflection takes place by spin-polarized quasiparticles tunneling from a ferromagnetic material to a d-wave superconductor. By comparing these experimental results with recent theoretical works on Andreev reflection, the existence of Andreev bound state due to the d-wave symmetry of the pair potential is verified in high-$T_c$ superconductor.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.555-560
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• 1990

High temperature superconducting films of $YBa_2Cu_3O_{7-x}$ were fabricated on the (100) single crystal faces of YSZ (yttria stabilized zirconia) and SrTi$O_3$ by aerosol spray using ultrasonic atomization. The superconducting phase was formed by a three-step process: (a) spraying of a stoichiometric solution of nitrates of yttrium, barium, and copper on heated substrates kept at 250$^{\circ}C$, (b) preheating of the sprayed films in air at 550$^{\circ}C$, and (e) sintering of the films in flowing oxygen at 950$^{\circ}C$, followed by furnace cooling. Resistances of the films were measured by the dc four-probe method and superconductivity was confirmed above the liquid nitrogen temperature.

• Journal of TMJ Balancing Medicine
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• v.5 no.1
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• pp.16-19
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• 2015

The purpose of this study was to report the effect of Yinyang balancing appliance (YBA) of Functional Cerebrospinal Therapy (FCST) and Korean medicine methods treating idiopathic scoliosis. YBA was applied for 146 times from 29th March 2014 to 5th September 2015. Herbal medicine used for treatment were Yeonggamgangmisinhaintang, Eokgansangagambang, Gamihangchetang. The change of symptoms was evaluated by Visual Analogue Scale. When treated with YBA and herbal medicine, the patient showed improvement. After about 1 year, the patient was recovered completely. This case showed that YBA and herbal medicine can be effective to improve idiopathic scoliosis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.239-242
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• 2000

To fabricate YBa$_2$Cu$_3$O$_{x}$ thick film using diffusion process, $Y_2$BaCuO$_{5}$ and BaO+CuO as the material of substrate and the doping material were selected. CeO$_2$ in the doping material was mixed. As another doping material, YBa$_2$Cu$_3$O$_{x}$ was prepared for the comparison with BaO+CuO doping material. Each doping material was patterned on $Y_2$BaCuO$_{5}$ substrate by the screen printing method and then was annealed above peritectic reaction temperature of YBCO with a few step. It could be observed by X-ray diffraction patterns and SEM photographs that through the diffusion process of the $Y_2$BaCuO$_{5}$ and BaO+CuO, the YBa$_2$Cu$_3$O$_{x}$ phase was formed. With an amout of addition of CeO$_2$, the thickness of a formed YBa$_2$Cu$_3$O$_{x}$ decreased. x/ decreased.