• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.345-345
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• 2007

본 연구는 x선 영상검출기 적용을 위한 $HgI_2$ 필름의 누설전류 특성 향상을 위한 연구로서, $HgI_2$기반의 다양한 물질을 이용하여 다층구조 방식으로 제작된 필름의 누설전류 특성평가 및 제작된 다층구조의 상부전극물질의 변화에 따른 누설전류 특성을 평가하였다. $HgI_2$기반 다층구조의 제작 물질은 Parylene, $PbI_2$, a-Se을 사용하여 시편(parylene/ITO, ITO/$HgI_2/PbI_2$/ITO, ITO/$HgI_2$/a-Se/ITO)을 제작하였으며, 필름 제작공정은 Screen print, PVD공정으로 다층구조 필름을 제작하였다. 또 한, 다층구조로 제작된 필름에 상부 전극물질은 Au, In, ITO를 사용하여 누설전류의 특성을 평가하였다. 측정 장치로 DC Power Supply(556H. EG&G : 50~200V), X 선 발생장치(Toshiba KXO-50N), 차폐체 (Al 및 Cu), Oscilloscope (LeCroy, LC334AM, USA), Electrometer (Keithley, 6517), Ion chamber 2060 (Radical Co.)을 이용하여, 제작된 $HgI_2$기반 다층구조 sample의 누설전류 특성을 실험하였다. 이 결과로 다층구조에 제작된 물질 및 상부전극에 따른 누설전류의 특성을 평가하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.618-618
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• 2013

Graphene is only one atom thick planar sheet of sp2-bonded carbon atoms arranged in a honeycomb crystal lattice, which has flexible and transparent characteristics with extremely high mobility. These noteworthy properties of graphene have given various applicable opportunities as electrode and/or channel for various flexible devices via suitable physical and chemical modifications. In this work, for the development of all-graphene devices, we performed to synthesize alternately patterned structure of mono- and multi-layer graphene by using the patterned Ni film on Cu foil, having much different carbon solid solubilities. Depending on the process temperature, Ni film thickness, introducing occasion of methane and gas ratio of CH4/H2, the thickness and width of the multi-layer graphene were considerably changed, while the formation of monolayer graphene on just Cu foil was not seriously influenced. Based on the alternately patterned structure of mono- and multi-layer graphene as a channel and electrode, respectively, the flexible TFT (thin film transistor) on SiO2/Si substrate was fabricated by simple transfer and O2 plasma etching process, and the I-V characteristics were measured. As comparing the change of resistance for bending radius and the stability for a various number of repeated bending, we could confirm that multi-layer graphene electrode is better than Au/Ti electrode for flexible applications.

• 자원환경지질
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• 제31권5호
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• pp.375-388
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• 1998

The purpose of this study is to investigate the ore genesis and occurrence of the Wondong polymetallic mineral deposits. The Pb-Zn, Fe and W-Mo mineralizations are found in skarn zones which formed mainly in or along the fault shear zones with the $N25-40^{\circ}W$ and $N10-50^{\circ}E$ directions, whereas the Cu-Mo mineralization is appeared hydrothermal replacement zone. The skarn minerals consist mainly of garnet and epidote, which were the last alteration phases between pneumatolytic and hydrothermal stages. The mineral paragenesis toward the late stage are as follows: arsenopyrite, scheelite, magnetite, pyrite, pyrrhotite, sphalerite, galena, chalcopyrite and molybdenite. Average ore grades are 0.33 g/t Au, 46.29 g/t Ag, 0.06% Cu, 4.4% Pb, 2.61% Zn and 29.39% Fe in tunnels, and 0.31 % Cu, 0.52% Pb, 6.29% Zn, 29.29% Fe, 0.03% Mo and 0.12% $WO_3$ in drill cores. Fluid inclusion data shows that Type I (liquid-rich), Type II (vapor-rich) and Type III (halite-bearing) inclusions are coexisted and their homogenization temperatures are quite similar. This indicates that boiling conditions have been reached during the mineralization. It is also likely that the ore solutions were evolved through the mixing between magmatic and meteoric waters. Rhyolite and quartz porphyry far the mineralization probably are not responsible of the Wondong polymetallic mineral deposits.

• 한국표면공학회지
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• 제24권1호
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• pp.25-30
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• 1991

The evaporation characteristics of Ag, Al, Au, Cr. Cu, In, Mg, Mn, Pb, Pd, Si, SiO, Sn, Ti and Zn with the various resistive heating sources have been studied. The employed sources are refractory metal (Mo, Ta and W) boats, W-wire, ceramic (usually Al2O3)-coated and -barriered refractory metal boats, and special boats such as baffled boats and intermetallic boats (nitride compound and graphite). We investigated the melting mode, evaporation rate at a specific power, and lifetime of the sources. A special boat holder is also discussed which is needed to cool the sources at a large heat capacity.

• 자원환경지질
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• 제54권1호
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• pp.49-60
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• 2021

금화광상은 백악기 경상퇴적분지 내에 분포하는 진주층 퇴적암 내에 발달한 열극을 충진하여 생성된 함 금-은 열수 맥상광상으로, 괴상, 각력상 및 호상 및 정동 조직 등 복합적인 조직적 특성을 보여준다. 금화광상 맥상 광화작용은 지구조적 운동(tectonic break)에 의하여 광화 1기(stage I)와 광화 2기(stage II)로 구분된다. 광화 1기는 금-은 광화작용이 진행된 주 광화시기로, 석영맥 내에 주된 함 금·은 광물인 에렉트럼과 함께 황화광물, 산화광물 및 황염광물 등이 산출한다. 광화 2기는 주 광화작용 이후 금속 광화작용이 이루어지지 않은 방해석맥의 생성 시기이다. 광화 1기는 광물 광생관계와 산출하는 광물 조합 특성 등에 의하여 3개의 세부 광화시기(초기, 중기, 후기)로 구분된다. 광화 1기의 초기에는 주로 황철석, 황동석 등의 황화광물이 철망간중석, 자철석 등의 산화광물을 수반하여 산출한다. 광화 1기 중기는 주된 금·은 광화작용이 광화 1기의 초기 말부터 계속하여 진행된 시기이다. 주로 에렉트럼과 함께 황동석, 섬아연석 등의 황화광물과 자철석 등의 산화광물이 산출되며, 텐난타이트 및 테트라히드라이트 등의 황염광물이 소량 수반되어 산출된다. 광화 1기 후기에는 방연석, 적철석과 함께 소량의 함 비스무스 황염광물이 산출하며 풍화작용 관련 이차광물의 생성이 진행되었다. 금화광상 광물 공생관계 변화는 열수계의 온도와 황 분압 조건의 감소 및 이에 수반된 산소 분압 조건의 증가 등의 환경변화가 반영된 결과이다. 유체포유물 실험·연구 결과를 종합하면, 초기 금화 열수계는 ≥410℃ 온도 조건에서 하부 마그마로부터 용리된 고 염농도(≥44 wt. % NaCl)를 갖는 유체와 금화광상 생성 심도 하부까지 순환하여 물-암석 반응이 진행된 천수 기원의 중 내지 저 염농도(≈7.0 wt. % NaCl)의 열수가 함께 유입되어 형성되었다. 그 이후 금화 열수계는 유체의 냉각, 비등작용 및 천수 혼입 등에 의하여 진화되었으며, 이들 진화기구에 수반된 냉각작용 및 화학성 변화 등에 의하여 온도 감소(≤200℃)와 염농도 변화(≤1.0 equiv. wt. % NaCl)가 야기되었다. 이러한 금화 열수계의 형성 및 진화 특성은 함 금-은 열수 맥상광상인 금화광상이 초기 천부 관입 마그마의 영향으로 마그마 우세 열수계로 부터 광화 후기 천수의 유입이 우세해지는 천열수계로 변환되는 점이적인 생성환경에서 생성된 맥상광상임을 지시한다.

• Progress in Superconductivity
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• 제8권1호
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• pp.81-86
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• 2006

We investigated resistance development in $Au/YBa_2Cu_3O_7(YBCO)$ thin film meander lines during high-power faults. The meander lines were fabricated by patterning 300 nm thick YBCO films coated with 200 nm thick gold layers into meander lines. A gold film grown on the back side of the substrate was also patterned into a meander line. The front meander line was connected to a high-power fault-test circuit and the back line to a DC power supply. Resistance of both lines was measured during the fault. They were immersed in liquid nitrogen during the experiment. Behavior of the resistance development prior to quench completion could be understood better by comparing resistance of the front meander lines with that of the back. Quench completion point could be determined clearly. Resistance and temperature at the quench completion point were not affected by applied field strength. The experimental results were analyzed quantitatively with the concept of heat transfer within the meander lines/substrate and to the surrounding liquid nitrogen. In analysis, the fault period was divided into three regions: flux-flow region, region prior to quench completion, and region after quench completion. Resistance was calculated for each region, reflecting the observation for quench completion. The calculated resistance in three regions was joined seamlessly and agreed well with data.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.735-738
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• 2000

The characteristics of wire electrical discharge machining (WEDM) are governed by many factors such as the power supply type, operating condition and electrode material. This work deals with the effect of wire electrode materials on the machining characteristics such as, metal removal rate, surface characteristics and surface roughness during WEDM A wire's thermal physical properties are melting point, electrical conductivity and vapor pressure. One of the desired qualities of wire is a low melting point and high vapor pressure to help expel the contaminants from the gap. They are determined by the mix of alloying elements (in the case of plain brass and coated wire) or the base core material(i.e. molybdenum). Experiments have been conducted regarding the choice of suitable wire electrode materials and influence of the properties of these materials on the machinability and surface characteristics in WEDM, the experimental results are presented and discussed from their metallurgical aspect. And the coating effect of various alloying elements(Au, Ag, Cu, Zn, Cr, Mn, etc.) to the Cu or 65-35 brass core on them was reviewed also. The removal rate of some coated wires are higher than that of 65-35 brass electrode wire because the wire is difficult to break due to the wire cooling effect of Zn evaporation latent heat and the Zn oxide on the surface is effective in preventing short circuit. The removal rate increases with increasing Zn content from 35, 40 and Zn coated wire

• 분석과학
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• 제37권1호
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• pp.47-62
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• 2024

Abu Gurdi area is located in the South-eastern Desert of Egypt which considered as volcanic massive sulfide deposits (VMS). The present work aims at investigating the ore mineralogy of Abu Gurdi region in addition to the effectiveness of the hydrometallurgical route for processing these ores using alkaline leaching for the extraction of Zn, Cu, and Pb in the presence of hydrogen peroxide, has been investigated. The factors affecting the efficiency of the alkaline leaching of the used ore including the reagent composition, reagent concentration, leaching temperature, leaching time, and Solid /Liquid ratio, have been investigated. It was noted that the sulfide mineralization consists mainly of chalcopyrite, sphalerite, pyrite, galena and bornite. Gold is detected as rare, disseminated crystals within the gangue minerals. Under supergene conditions, secondary copper minerals (covellite, malachite, chrysocolla and atacamite) were formed. The maximum dissolution efficiencies of Cu, Zn, and Pb at the optimum leaching conditions i.e., 250 g/L NaCO₃ - NaHCO₃ alkali concentration, for 3 hr., at 250 ℃, and 1/5 Solid/liquid (S/L) ratio, were 99.48 %, 96.70 % and 99.11 %, respectively. An apparent activation energy for Zn, Cu and Pb dissolution were 21.599, 21.779 and 23.761 kJ.mol^-1, respectively, which were between those of a typical diffusion-controlled process and a chemical reaction-controlled process. Hence, the diffusion of the solid product layer contributed more than the chemical reaction to control the rate of the leaching process. High pure Cu(OH)₂, Pb(OH)₂, and ZnCl₂ were obtained from the finally obtained leach liquor at the optimum leaching conditions by precipitation at different pH. Finally, highly pure Au metal was separated from the mineralized massive sulfide via using adsorption method.

• 자원환경지질
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• 제20권4호
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• pp.223-234
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• 1987

This paper describes the mode of occurrence and mineralogical properties of electrum from the Namseong Gold-Silver deposits, for the purpose of obtaining data on the characteristics of the ore deposits and the behavior of gold and silver during the mineralization. The gangue minerals are quartz, calcite, fluorite. Ore minerals are mainly composed of pyrite, sphalerite, chalcopyrite and galena with minor amount of argentite, electrum, pyrargyrite, native silver and unidenfied mineral(Cu-Fe-Ag-S series). Three stage of mineralization recognized are, from early to later, (I) pyrite-electrum stage (II) sphalerite-chalcopyrite-galena-argentite-electrum stage (III) sulfosalts stage. The filling temperature of fluid inclusions in quartz ranges from $225^{\circ}$ to $335^{\circ}C$. The value of sulfur fugacity estimated by means of electrum-tarnish method ranges from $10^{-11.5}$ to $10^{-14}$ atm. The compositional heterogeneity within a single grain with respect to gold concentration is common in the Namseong electrums Chemical composition of electrum ranges generally between 25~45 atom% Au. Its gold content decreases in late stages of mineralization.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권6호
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• pp.211-215
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• 2003

Alternating current (AC) losses of two Bi-2223 ([Bi, Pb] : Sr : Ca : Cu :O = 2:2:2:3) tapes [one untwisted (Tape I, twist-pitch of $\infty$ mm) and the other with a twist-pitch of 8mm (Tape II) ] were measured and compared. These samples, produced by the powder-in-tube (PIT) method, are multi-filamentary and have a Ag/Au and Ag matrix, respectively. Susceptibility measurements were conducted while cooling in a magnetic field. Flux loss measurements were conducted as a function of ramping rate, frequency and field direction. The AC flux loss increases as the twist-pitch of the tapes decreased, in agreement with the Norris Equation.