• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.71-73
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• 2005

Ferroelectric PZT heterolayered thick films were fabricated by the alkoxide-based sol-gel method. PZT(20/80) and PZT(80/20) paste were made and alternately screen-printed on the alumina substrates. The coating and drying procedure was repeated 4 times to form the heterolayered thick films. The thickness of the PZT heterolayered thick films was approximately 60 mm. All PZT thick films showed the typical XRD patterns of a perovskite polycrystalline structure. The relative dielectric constant and the dielectric loss of the PZT thick films sintered at $1050^{\circ}C$ were 1382 and 1.90%, respectively. The remanent polarization and coercive field of the PZT thick films sintered at $1050^{\circ}C$ were $14.15{\mu}C/cm^2$ and 19.13kV/cm, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.474-477
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• 2002

We performed a continuous heat treatment experiment for long Si$_2$Sr$_2$CaCuO$_{x}$ (Bi2212) superconductor tapes on copper substrates. A precursor that contains a mixture of Bi$_2$O$_3$, SrCO$_3$, and CaCO$_3$ powders was prepared and screen-printed on Cu tapes. The screen- printed tapes were thermally treated by consecutive processes with various temperature settings using an air-filled tube furnace. The diffraction patterns and the microstructures of the high temperature superconductor thick films were analyzed by X-ray diffractometry (XRD) and optical Microscopy respectively, and the critical temperatures of the superconducting thick films were measured. The critical temperatures of the superconducting films were measured to be about 77K, and the films'crystallographic c-axes were confirmed to be normal to the film surfaces by XRD and morphology observation. We also observed that the thick superconducting layer is formed and aligned on the copper substrate via partial melted state that consists of a liquid phase and a secondary phase.e.

• Animal cells and systems
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• v.1 no.2
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• pp.355-361
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• 1997

We have screened available chromosomal deficiencies on the X chromosome for genetic loci whose zygotic expression is required for body-wall muscle development during embryogenesis in Caenorhabditis elegans. Previously, it had been reported that no sign of muscle development was detected in nullo-X embryos arrested at an early stage of embryogenesis. Based on this observation, it has been suggested that genetic loci exist on the X chromosome whose zygotic expression is essential for body-wall muscle formation. In order to identify such myogenic loci, 9 chromosomal deficiencies covering approximately 45% of the X chromosome have been tested. Homozygous embryos from these deficiency strains were collected and terminal phenotypes of arrested embryos were observed by Nomarski microscopy. As a secondary assay, monoclonal antibodies against two myosin heavy chain (MHC) isoforms, the products of the myo-3 and unc-54 genes, were used to detect body-wall muscle differentiation. All the homozygous deficiency embryos were positively stained with both MHC antibodies and muscle twitching movement was observed in most cases. Combined with previously analyzed deficiencies, our deficiency screen has covered approximately 70% of the X chromosome. We conclude that the regions covered by the available deficiencies on the X chromosome do not include any myogenic locus required for body-wall muscle formation. Alternatively, the possibility that nullo-X embryo may not form body-wall muscle due to a general failure to differentiate during embryogenesis remains to be tested.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.69-74
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• 2006

Thick film $H_2$ sensors were fabricated using $SnO_2$ loaded with $Ag_2O$ and $PtO_x$. The composition that gave the highest sensitivity for $H_2$ was in the weight% ratio of $SnO_2 : PtO_x : Ag_2O$ as 93 : 1 : 6. The nano-crystalline powders of $SnO_2$ synthesized by sol-gel method were screen printed with $Ag_2O$ and $PtO_x$ on alumina substrates. The fabricated sensors were tested against gases like $H_2$, $CH_4$, $C_3H_8$, $C_2H_5OH$ and $SO_2$. The composite material was found sensitive against $H_2$ at the working temperature $130^{\circ}C$, with minor interference of other gases. The $H_2$ gas as low as 100 ppm can be detected by the present fabricated sensors. It was found that the sensors based on $SnO_2-Ag_2O-PtO_x$ system exhibited the high performance, high selectivity and very short response time to $H_2$ at ppm level. These characteristics make the sensor to be a promising candidate for detecting low concentrations of $H_2$.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.98-101
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• 2005

변환 효율이 $16\%$에 근접하는 다결정 실리콘 태양전지를 위한 열처리 공정에 대한 연구를 수행하였다. 고속 열처리 공정이 가능한 RTP 를 사용하여 다결정 실리콘 태양전지의 효율 향상에 요구되는 PECVD $SiN_x$ 반사방지막을 이용한 결정 결함의 수소화 효과를 극대화하는 동시에 양산 가능한 screen-printed contacts 의 특성 (FF >0.76) 올 최적화함으로써 다결정 실리콘 태양전지의 변환 효율을 $15.9\%$까지 향상시킬 수 있었다.

• Communications for Statistical Applications and Methods
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• v.21 no.4
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• pp.317-325
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• 2014

Consider a nonlinear transform ${\Phi}(x)$ of x in $\mathbb{R}^p$ to Hilbert space H and assume that the dot product between ${\Phi}(x)$ and ${\Phi}(x^{\prime})$ in H is given by < ${\Phi}(x)$, ${\Phi}(x^{\prime})$ >= K(x, x'). The aim of this paper is to propose a mathematical technique to take screen shots of the multivariate dataset mapped to Hilbert space H, particularly suited to Gaussian kernel $K({\cdot},{\cdot})$, which is defined by $K(x,x^{\prime})={\exp}(-{\sigma}{\parallel}x-x^{\prime}{\parallel}^2)$, ${\sigma}$ > 0. Several numerical examples are given.

• Progress in Superconductivity
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• v.5 no.2
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• pp.132-135
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• 2004

We fabricated YBCO thick films by using a screen printing method with $Y_2$BaCuO$_{5}$(Y211) and BaCO$_3$ powders on Cu-substrate in $N_2$ atmosphere. Cu-sheathed YBCO thick film process is more simple and economic than YBCO coated conductor methods. The heat treatment is performed in the range of 860 - 875 $^{\circ}C$ for 5 min in the tube furnace of $N_2$ atmosphere. The flow rate of $N_2$ gas is fixed 60 $m\ell$/min. Microstructure and phases of thick films were investigated by optical microscope, X-ray diffraction(XRD) and SEM. At heat-treatment temperature, the thick films were partially melted by liquid reaction between CuO of oxidized copper substrate and the powders screen-printed on Cu-sheath. During the heat-treatment procedure, YBCO superconducting grains nucleate.e.

• Journal of the Korean Ceramic Society
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• v.31 no.12
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• pp.1483-1490
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• 1994

YBa2Cu3Ox-Ag(YBCO-Ag) thick films were fabricated on the zirconia substrate by a screen printing method. The starting powder was a mixture of YBCO, prepared by a coprecipitation in oxalic acid, and Ag2O. The influence of heat treatment conditions on properties of thick films was investigated. It was observed that Jc of thick films was directly proportional to the orientation factor of thick films and the optimimum preparation condition was the heat treatment of thick films at 100$0^{\circ}C$ for 3 min in O2. The improvement of Jc by the addition of Ag was considered as a result of the suppression of microcracks in the films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.478-481
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• 2002

We carried out the experiments for fabricating $Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{x}$(Bi2223) superconductor thick films on Cu tapes. Cu-free (Bi,Pb)-Sr-Ca-0 powder mixtures were screen- printed on Cu tapes and heat-treated at 840-$860^{\circ}C$ for several minutes in air. Surface microstructures and phases of films were analyzed by XRD and optical microscope. The electric properties of superconducting films were examined by the four probe method. At heat-treatment temperature, the printing layers were in a partially molten state by liquid reaction between CuO in the oxidized copper tape and the precursors which were printed on Cu tapes. During the heat-treatment procedure, it is thought that Bi2223 superconducting particles nucleate at interfaces between Bi2212 phase and liquid.

• Journal of the Korean Ceramic Society
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• v.30 no.12
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• pp.1007-1014
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• 1993

YBa2Cu3Ox(YBCO) thick films were prepared by a screen printing of the powders, obtained by a coprecipitation in oxalic acid, on the Y2O3-stabilized zirconia substrates and their superconducting properties were determined. TC, JC and the orientation factor of the thick films increased with increasing temperature up to 103$0^{\circ}C$ and then the superconducting properties disappeared with further heat treatments. The optimization of JC was achieved by heating thick films at 103$0^{\circ}C$ for 7min. In this case the TC of the thick film was determined to be 87.5K. It was observed that TC of thick films depends on the orthorhombicity and JC is likely governed by a microstructure of YBCO rather than by the orientation factor.