• Journal of the Korean Applied Science and Technology
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• v.33 no.2
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• pp.352-360
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• 2016

The purpose of this study was to determine the electrochemical properties develop DSA electrode for sewage sludge solubilization. Using Ir as a main catalyst, the catalyst selected for the sewage sludge solubilization durability and proceeds to functional electrode suitable for sewage sludge electrolysis experiment were obtained the following results. Less mass reduction of the sintering temperature of the main catalyst, Ir coated electrodes, the endothermic reaction zone $300^{\circ}C$ to $500^{\circ}C$, which was selected from a range of experiments. The efficiency of the catalyst results came up to $350^{\circ}C$ best. Each Binder stars (Ta, Sn, W) in this experiment was the biggest catalyst efficiency at $350^{\circ}C$. Used as a binder, $TaCl_5$, $SnCl_4$, $WCl_6$ of the Ta and without affecting the other characteristics of the main catalyst than Sn, W. For the 50% $IrO_2$ electrode is 1.4 V (vs. Ag / AgCl) in a current of about $29mA/cm^2$ was caused to evaluate the effectiveness of the electrode.

• ETRI Journal
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• v.13 no.2
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• pp.42-53
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• 1991

고유전율 적충세라믹 커패시터 소재인 $BaTiO_3$ 자기물은 일반적으로 큐리오도인 약 $120^{\circ}C$부근에서 유전율이 최고 약 10,000정도로 증가한 다음 급격히 감소하므로 적절한 이동체를 첨가하여 큐리온도를 상온으로 이동시켜 상온에서 최대 유전율을 이용하여야 한다. 그리고$BaTiO_3$ 자기물은 $1300^{\circ}C$이상의 고온소결시 고가인 Pd전극이 요구된다. 그러나 자기물의 소결온도를 저온화화면 저가의 Ag합금으로 전극재료를 대체할 수 있다. 본 연구에서는 이동제로서 $CaSnO_3$ 를 이용하여 큐리온도를 상온으로 이동시켰다. 또한 소결온도를 저온화하기 위하여 $BaTiO_3$ 세라믹에 여러가지 산화물을 첨가하여 소결현상을 살펴보았다. 실험결과 첨가제를 넣지 않은 경우 소결온도는 $1350^{\circ}C$의 고온이 필요한 반면, $CuO,B_2O_3$는 $1050^{\circ}C$의 낮은 온도에서도 치밀화와 입도성장이 잘 일어났다. 특히 $B_2$$O_3$ 를 첨가한 경우는 $1250^{\circ}C$이상에서 소결할 때 절연저항이 낮아 유전손실이 큰 문제점을 보였지만, 최대 유전율이 11,000 정도로 높고, 양호한 유전율의 온도변화 특성을 나타내어 우수한 고유전율 소재의 첨가제로 응용될 가능성을 보였다

• Journal of the Microelectronics and Packaging Society
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• v.18 no.1
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• pp.35-39
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• 2011

Shearing characteristics of Sn-3.0wt%Ag-0.5wt%Cu ball for standardization of high speed shear test were investigated. The solder ball of 450 ${\mu}m$ in diameter was reflowed at $245^{\circ}C$ on FR4 PCB (Printed Circuit Board) to prepare a sample for the high-speed shear test. The metal pads on the PCB were OSP (Organic Solderability Preservative, Cu pad) and ENIG (Electroless Nickel/Immersion Gold, i.e CulNi/Au). Shearing speed was varied from 0.5 to 3.0 m/s, and tip height from 10 to 135 ${\mu}m$. As experimental results, for the OSP pad, a ductile fracture increased with tip height, and it decreased with shearing speed. In the case of ENIG pad, the ductile fracture increased with the tip height. The tip height of 10 ${\mu}m$ (2% of solder ball diameter) was unsuitable since the fracture mode was mostly pad lift. Shear energy increased with increasing shearing tip height from 10 to 135 ${\mu}m$ for both of OSP and ENIG pads.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.389-389
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• 2011

Transparent conductive oxide (TCO) 박막은 디스플레이 및 태양전지 등 광범위한 분야에서 적용되고 있으며, 특히 indium tin oxide (ITO)는 낮은 전기적 저항과 우수한 광투과도를 가지고 있어서 이미 많은 분야에 적용되고 있다. 본 연구는 RF와 DC를 혼용한 마그네트론 스퍼터링 공정을 활용하여 ITO 박막 특성 및 이를 활용한 유기태양전지 적용에 관한 것이다. UV-O3 처리된 glass 기판위에 thermal evaporation 방식으로 밀착력을 높이기 위하여 Cr을 5 nm 두께로 증착한 후 Al을 95 nm 증착하였다. 그 위에 스퍼터링 공정으로 ITO 박막을 In2O3:SnO2 target (10wt% SnO2)을 사용하여 1.0 mTorr의 공정압력(Ar:O2=30:1), 50W의 RF power 및 0.11kW의 DC power에서 50~250 nm의 두께로 증착하였다. ITO 박막의 결정구조 및 표면 형상은 x-ray diffraction (XRD) 및 scanning electron microscope (SEM)을 사용하여 분석하였으며, 전기적 특성은 four-point probe법으로 비저항값을 측정하였다. 또한 높은 광변환효율을 가지는 태양전지 제작을 위하여, 다양한 두께의 ITO 박막을 사용하여 ITO/ZnO/P3HT:PCBM/PEDOT/Ag 구조의 유기태양전지를 제작하여 소자 특성을 최적화 하였다.

• 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.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1155-1159
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• 1999

Thin film solar cells on a glass/$SnO_2$ substrate with p-SiC/i-Si/n-Si heterojunction structures were fabricated using a plasma-enhanced chemical-vapor deposition system. The photovoltaic properties of the solar cells were examined with varying the gas phase composition, x=$CH_4/\;(SiH_4+CH_4)$, during the deposition of the p-SiC layer. In the range of x=0~0.4, the efficiency of solar cell increased because of the increased band gap of the p-SiC window layer. Further increase in the gas phase composition, however, led to a decrease in the cell efficiency probably due to in the increased composition mismatch at the p-SiC/i-Si layers. As a result, the efficiency of a glass/$SnO_2$/p-SiC/i-SiC/i-Si/n-Si/Ag thin film solar cell with $1cm^2$ area was 8.6% ($V_{oc}$=0.85V, $J_{sc}$=16.42mA/$cm^2$, FF=0.615) under 100mW/$cm^2$ light intensity.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.71-77
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• 2011

Main parameters of the screen printing were determined and the printing parameters were optimized for 0402, 0603, and 1005 chips in this study. The solder pastes used in this study were Sn-3.0Ag-0.5Cu and Sn-0.7Cu. The process parameters were stencil thickness, squeegee angle, printing speed, stencil separating speed and gap between stencil and PCB. The printing pressure was fixed at 2 $kgf/cm^2$. From ANOVA results, the stencil thickness and the squeegee angle were determined to be main parameters for the printing efficiency. The printing efficiency was optimized with varying two main parameters, the stencil thickness and the squeegee angle. The printing efficiency increased as the squeegee angle was lowered under 45o for all chips. For the 0402 and the 0603 chips, the printing efficiency increased as the stencil thickness decreased. On the other hand, for the 1005 chip, the printing efficiency increased as the stencil thickness increased.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.1-26
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• 1994

The purpose of this study was to investigate the dissolution components during corrosion of amalgams and to identify surface corrosion products in the modified Fusayama artificial saliva. Four type of amalgam alloys were used: low copper lathe cut amalgam alloy (Cavex 68), low copper spherical amalgam alloy (Caulk Spherical Alloy), high copper admixed amalgam alloy (Dispersalloy) and high copper single composition amalgam alloy (Tytin). Each amalgam alloy and Hg were triturated according to the manufacturer's direction by means of mechanical amalgamator (Capmaster, S.S.White), and then the triturated mass was inserted into the cylindrical metal mold which was 10mm in diameter and 2.0mm in height and condensed with compression of 150kg/$cm^2$ using oil pressor. The specimens were removed from the mold and stored at room temperature for 7 days and cleansed with distiled water for 30 minutes in an ultrasonic cleaner. The specimens were immersed in the modified Fusayama artificial saliva for the periods of 1 month, 3 months and 6 months. The amounts of Hg, Cu, Sn and Zn dissolved from each amalgam specimen immersed in the artificial saliva for the periods of 1 month, 3 months and 6 months were measured using Inductivity Coupled Plasma Atomic Emission Spectrometry (ICPQ-1000, Shimadzu, Japan) and amount of Ag dissolved from amalgam specimen was measured using Atomic Absorption Spectrophotometry (Atomic Absorption/Flame emission spectrophotometer M-670, Shimadzu, Japan). A surface corrosion products of specimens were analysed using Electron Spectroscopy Chemical Analyser (ESCA PHI-558, PERKIN ELMER, U.S.A.). The secondary image and back scattered image of corroded surface of specimens was observed under the SEM, and the corroded surface of specimens was analysed with the EDX. The following results were obtained. 1. The dissolution amount of Cu was the most in high copper admixed amalgam(Dispersalloy) and the least in high copper single composition amalgam(Tytin). 2. Sn and Zn were dissolved during all the experiment periods, and dissolution amounts were decreased as the time elapsed. 3. Initial surface corrosion products were ZnO and SnO. 4. Corrosion of ${\gamma}$ and ${\gamma}_2$ phase in low copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in low copper spherical amalgam(Caulk Sperical Alloy). 5. Corrosion of ${\gamma}$ and $\eta$' phase in high copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in high copper admixed amalgam(Dispersalloy). 6. Sn-Cl was produced in the subsurface of low copper amalgams and high copper admixed amalgam.

• Journal of Conservation Science
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• v.29 no.4
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• pp.355-366
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• 2013

Diverse scientific analyses, including microstructure, ICP-AES, SEM-EDS, and P-XRF(Bench Top type and Gun type), were carried out on 6 bronze artefacts which handed from generation to generation. Also, we attempted to study applicability for authenticity of the bronze artefacts using scientific analyses based on the specific element. The results of ICP-AES analysis showed that the bronze were formed from an alloy of Cu, Sn, Pb with trace elements such as Ag, As, Co, Fe, but there were not Zn found. The result of P-XRF are 10~25% lower in Cu and 10~20% higher in Sn than that of ICP-AES. This is because of destannification that the compound of $SnO_2$ are present on the surface. The results of SEM-EDS represented that there is lead segregation. It was difficult to study applicability for authenticity of bronze artefact according to the microstructures and chemical components of the bronze artefacts. Therefore, as bronze artefacts have shown different corrosion materials depending on the buried environment and conserving environment, identifying the authenticity would be possible on the basis of the additional researches on the corrosion and comparative research of ancient art.

• Progress in Superconductivity
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• v.14 no.1
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• pp.1-10
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• 2012

We fabricated a closed coils by using resistive-joint method and the joint resistance of the coils were estimated by field decay technique in liquid nitrogen. We used the Runge-kutta method for the numerical analysis to calculate the decay properties. The closed coil was wound by $(Bi,Pb)_2Sr_2Ca_2Cu_3O_x$/Ag tape. Both ends the tape were overlapped and soldered to each other. The current was induced in a closed coils by external magnetic flux density. Its decay characteristic was observed by means of measuring the magnetic flux density generated by induced current at the center of the closed coil with hall sensor. The joint resistance was calculated as the ratio of the inductance of the loop to the time constants. The joint resistances were evaluated as a function of critical current of loop, contact length, sweep time, and external magnetic flux density in a contact length of 7 cm. It was observed that joint resistance was dependent on contact length of a closed coil, but independent of critical current, sweep time, and external magnetic flux density. The joint resistance was measured to be higher for a standard four-probe method, compared with that for the field decay technique. This implies that noise of measurement in a standard four-probe method is larger than that of field decay technique. It was estimated that joint resistance was $8.0{\times}10^{-9}{\Omega}$ to $11.4{\times}10^{-9}{\Omega}$ for coils of contact length for 7 cm. It was found that 40Pb/60Sn solder are unsuitable for persistent mode.