• 한국분말재료학회지
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• 제11권5호
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• pp.421-426
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• 2004

The microstructure and mechanical property of hot-pressed $Al_2O_3/Cu$ composites with a different temperature for atmosphere changing from H$_{2}$ to Ar have been studied. When atmosphere-changed from H$_{2}$ to Ar gas at 145$0^{\circ}C$, the hot-pressed composite was characterized by inhomogeneous microstructure and low fracture strength. On the contrary, when atmosphere-changed at low temperature of 110$0^{\circ}C$ the composite showed more homogeneous microstructure, higher fracture strength and smaller deviation in strength. Based on the thermodynamic consideration and microstructural analysis, it was interpreted that the Cu wetting behavior relating to the formation of CuAlO$_{2}$ is probably responsible for strong dependence of microstructure on atmosphere changing temperature. The reason for a strong sensitivity of fracture strength and especially of its deviation to atmosphere changing temperature was explained by the microstructural inhomogeneity and by the role of CuAlO$_{2}$ phase on the interfacial bonding strength.

• 한국자기학회지
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• 제15권4호
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• pp.217-220
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• 2005

제일원리적 에너지 띠 계산 방법인 전 전자 총 퍼텐셜 선형보강평면파동(all-electron full-potential linearized augmented plane ave) 방법에 일반기울기근사(generalized gradient approximation)를 채용하여 Ag(001) 표면 위에 [110] 방향으로 놓인 Fe 선의 전자구조와 자성을 이론적으로 연구하였다. Fe 선의 원자당 자기모멘트는 $3.02\;{\mu}_B$로 Cu(001) 위에 놓인 Fe[110] 선의 값($2.99\;{\mu}_B$) 보다 약간 컸다. Fe 선의 자기모멘트가 상당히 증가한 것은 이웃한 결합수가 줄어들고 그 결과로 Fe-d 전자상태의 띠폭이 줄어들어 국소화 되고 스핀분리가 증가하였기 때문이다. Fe-d 전자상태의 띠 폭은 약 1.6eV였으며 스핀분리는 약 3.2 eV였다.

• 한국주조공학회지
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• 제36권1호
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• pp.1-9
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• 2016

Improvement of the mechanical properties of a commercial aluminium casting alloy, A356, was achieved through an optimised combination of alloying elements, modification, and heat treatment. 0.7 wt.% Cu and an additional 0.2 wt.% Mg were added to an Al-7Si-0.35Mg alloy for strengthening at both room and elevated temperatures, whilst a subsequent decrease in the ductility was compensated for by the modification of eutectic Si by Sr addition at a level of up to 110 ppm. It was found that the dissolution of Cu-rich or Mg-rich phases could be maximised by solid-solutionising an alloy with 40 ppm Sr at $530^{\circ}C$, increasing the tensile and yield strengths to 350 MPa and 297 MPa, respectively, with a reasonably high strain of 5% after peak-aging at $210^{\circ}C$. Further addition of Sr up to 110 ppm is, however, more likely to interfere with the dissolution of the Cu-rich or Mg-rich phases during solid solution treatment, resulting in a slight decrease in both tensile and yield strengths at room temperature. Besides the Cu addition, such undissolved phases, on the other hand, may contribute to elevated temperature strength at $200^{\circ}C$.

• Current Photovoltaic Research
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• 제8권1호
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• pp.27-32
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• 2020

CuS thin films were deposited on glass substrates at room temperature by RF magnetron sputtering. The structural and optical properties of CuS thin films grown by varying RF-power from 40 W to 100 W were studied. From the XRD analysis, we confirmed hexagonal crystal structures grown in the preferred orientation of the (110) plane in all CuS thin films, and the intensity of the main diffraction peak increased in proportion to the increase of RF-power. In the case of CuS thin film deposited at 40W, small-sized particles formed a thin and dense surface morphology with narrow pore spacing, relatively. As the power increased, the grain size and grain boundary spacing increased sequentially. The peaks for the binding energy of Cu 2p_3/2 and Cu 2p_1/2 were determined at 932.1 eV and 952.0 eV, respectively. The difference in binding energy for the Cu²⁺ states was the same at 19.9 eV regardless of process parameters. The transmittance and band gap energy in the visible region tended to decrease with increasing sputtering powers.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
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• pp.63-67
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• 2003

Electromigration characteristics of $SnAg_3Cu_{0.7}$ and eutectic SnPb solder were studied using thin stripe-type test structures. Significant changes in the microstructure of two solders were observed after electromigration test, in which the temperature and the current density were varied from 90 to $110^{\circ}C$ and from $4.0\times10^4\;A/cm^2\;to\;9.2\times10^4\;A/cm^2$. In SnAgCu solders, hillocks were main]y observed near the anode end. From resistance measurements, it was calculated that the activation energy of the SnAgCu solder for electromigration was 1.04 eV And in eutectic SnPb without the effect of pads, while depleted region was found near cathode end, Sn-rich hillocks were observed near the anode end. During eutectic SnPb electromigration, it were observed that electromigration behavior had two migration modes.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2430-2441
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• 2018

Selenium (Se)-rich binary Cu-Se and In-Se nanoparticles (NPs) were synthesized by a modified heat-up method at low temperature ($110^{\circ}C$) using the gum exudates from a cherry blossom tree. Coating of CISe absorber layer was carried out using Se-rich binary Cu-Se and In-Se NPs ink without the use of any external binder. Our results indicated that the gum used in the synthesis played beneficial roles such as reducing and capping agent. In addition, the gum also served as a natural binder in the coating of CISe absorber layer. The CISe absorber layer was integrated into the solar cell, which showed a power conversion efficiency (PCE) of 0.37%. The possible reasons for low PCE of the present solar cells and the steps needed for further improvement of PCE were discussed. Although the obtained PCE is low, the present strategy opens a new path for the fabrication of eco-friendly CISe NPs solar cell by a relatively chief non-vacuum method.

• 한국미생물·생명공학회지
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• 제27권1호
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• pp.35-40
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• 1999

Alternan known as a kind of dextran is a linear and cyclic polysaccharide which is synthesized with sucrose by alternaansucrase (EC2.4.1.140) of Leuconostoc mesenteroides. But this polysaccharide is different from dextran in its structure and other properties. For the purpose of applying alternan for the food, cosmetic, and pharmaceutical industries, we isolated an excellent alternan-porducing strain, Leu. mesenteroides CBI-110. The optimum culture conditions were studied to improve the yield, and the activity of alternansucrase was increased up to 33U/ml in the optimum culture media. The concentrations of $Mn^{2+}$ and $Cu^{2+}$ ions were 0.01% and 0.03%, respectively, for the effective production of alternan. Finally, we obtained 25.6g/L of alternan.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2014년도 자성 및 자성재료 국제학술대회
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• pp.110-111
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• 2014

• 한국재료학회지
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• 제4권3호
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• pp.268-279
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• 1994

단일상을 갖는 $Bi_2S_2CaCu_2O_{8+x}$ (2212)의 x-ray 분말 pattern을 a=5.408, c=30.83 $\AA$의 격자상수 및 역격자 벡터 $q^*=0.211b^*-c^*$을 갖는 pseudo tetragonal subcell을 이용하여 모두 index하였다. 임계온도 110K를 갖는 $Bi_2S_2CaCu_2O_{10+x}$ 상은 incommensurate supercell에 속하는 매우 많은 x-ray분말선들을 가지고 있다. Indixing guide로 전자회절사진(electron diffraction photographs)을 이용 x-ray분말 pattern에 대한 지수결정방법을 얻었다.$Bi_2S_2CaCu_2O_{10+x}$(2223)의 단위세표(unit cell)는 기하학적으로 격자상수 a=5.411, b=5.420, c=37.29(2) A을 갖는 orthorhombic subcell이다. Supercell반사 지수들은 subcell의 파 벡터 $\pm q^*=0.211b^*-0.78c^*$을 갖는 k,1지수로부터 영향을 받은 것이다. b 방향으로의 inconnensurate성분 $\delta$는 두 상에 대해 다 같으나, 2212에서 2223 상으로의 변환에 따라 c 방향으로의 초격자성분(superlattic component)은 connensurate($\varepsilon$=1)로부터 incommensurate($\varepsilon$=0.78)로 변한다.

• 헤리티지:역사와 과학
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• 제48권2호
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• pp.110-119
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• 2015

풍납토성은 백제 초기의 토성으로 토기 및 주거유물과 더불어 다량의 청동기가 출토되었다. 본 연구에서는 풍납토성 출토 청동기의 제작기술과 청동기 내에 포함된 납 원료의 산지를 추정하기 위해 출토지가 명확한 7점의 청동기 시편에 대한 분석을 실시하였다. 금속심이 남아있는 4점에 대한 미세조직 및 성분 분석 결과, 3점은 Cu-Sn-Pb의 3원계 합금이며 나머지 1점은 Cu-Sn의 2원계 합금의 청동기로, 조직 내에 뚜렷한 쌍정이 관찰 됨을 확인할 수 있다. 또한 주성분 이외에 S(황), Fe(철)가 검출되어 황동광($CuFeS_2$) 또는 반동광($Cu_5FeS_4$)을 원광석으로 사용하였음을 알 수 있다. 납동위원소비 분석을 이용한 산지 추정 결과 4점의 청동포수, 청동세환 2점, 청동유물 편(나)의 청동기에 산지는 zone 3(충청남 북도, 전라남 북도)의 지역으로 표시되었다. 청동유물 편(라)는 중국 북부로 표시되었으며 청동검은 zone 2(경상남 북도)의 원료를 사용하여 제작하였을 것으로 판단된다.