• 대한금속재료학회지
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• 제49권11호
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• pp.905-909
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• 2011

The formation of front metal contact silicon solar cells is required for low cost, low contact resistance to silicon surfaces. One of the available front metal contacts is Ni/Cu plating, which can be mass produced via asimple and inexpensive process. A selective emitter, meanwhile, involves two different doping levels, with higher doping (${\leq}30{\Omega}/sq$) underneath the grid to achieve good ohmic contact and low doping between the grid in order to minimize the heavy doping effect in the emitter. This study describes the formation of a selective emitter and a nickel silicide seed layer for the front metallization of silicon cells. The contacts were thickened by a plated Ni/Cu two-step metallization process on front contacts. The experimental results showed that the Ni layer via SEM (Scanning Electron Microscopy) and EDX (Energy dispersive X-ray spectroscopy) analyses. Finally, a plated Ni/Cu contact solar cell displayed efficiency of 18.10% on a $2{\times}2cm^2$, Cz wafer.

• Tribology and Lubricants
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• 제25권6호
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• pp.409-413
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• 2009

This paper presents the hardness and friction characteristics of pb-free pin-bush bearing metal, which is manufactured by a centrifugal casting technology. A bronze metal with a high hardness and low friction properties is usually used for Diesel engine pin-bush bearing and high pressure cylinder. Pb-free metal for pin-bush bearings shows a little high hardness of 120 Hv compared with that of a conventional Pb bearing metal of 100~110 Hv. In general, the friction coefficient of pin-bush bearings is affected by a rotating speed and a load for various rubbing contact modes. But a contact load is more influential parameter when the contact rubbing mode transits from a mixed lubrication to a dry friction contact. The experimental result shows that the friction coefficient is more unstable at the dry contact mode compared with that of other two rubbing modes such as oil film contact and mixed friction conditions.

• 대한기계학회논문집
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• 제14권5호
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• pp.1129-1137
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• 1990

본 연구에서 사용된 유한요소 방정식은 국부 질점좌표계(natural convected coordinate system)를 이용하여 변형을 묘사하는 대변형을 고려한 탄소성 증분 수식을 사용하였고, 국부 질점 좌표계를 사용함으로써 변형도 성분이나 구성 방정식의 성분들 에 대한 좌표 변환 과정을 생략할 수 있다. 재료는 수직 이방성으로 가정하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.272-272
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• 2009

Screen-printing metal contact is typically applied to the solar cells for mass production. And metal paste is used widely for rear contact formation of silicon solar cells. However, Screen-printing solar cell metal paste contact has low aspect ratio, low accuracy, high resistivity, hard control of unclean process. In this paper is to develop resistivity of rear contact for silicon solar cells applications. 4-point prove result, This resistivity of rear contact by Al evaporation was measured about $3.56{\times}10^6{\Omega}{\cdot}cm$ less than screen printed solar cell about $52.6{\times}10^6{\Omega}{\cdot}cm$.

• 한국세라믹학회지
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• 제19권1호
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• pp.24-34
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• 1982

The effect of the several variables on wetting of AISIB1113 steel by molten glass was studied by Sessible-drop method. Experimental variables were temperature, firing atmospheres, Fe2O3 addition to the sealing glass and steel surface conditions. The degree of wetting in terms of contact angles between molten glass and metal tested at different test conditions was analyzed by using Young's equation. The results showed that contact angles in H2 atmosphere in the glass metal systems were high but in N2 atmosphere, were small for studied glass metal systems. Especially, when the glass drop was in contact with oxidized steel in N2 atmosphere, The best adherence with contact angle of approximately 9°was obtained. In the case of Fe2O3 addition in glass contact angles subtantially increased due to the increase of surface tension of glass. Wetting phenomena were also discussed under the basis of these experimental results.

• 대한치과보철학회지
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• 제61권3호
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• pp.198-203
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• 2023

목적. 이 연구의 목적은 건강한 치열에서 치실 방법을 사용하여 인접면 접촉을 비교하고, 이를 셀룰로이드 스트립 방법, 금속 스트립 방법과 비교하여, 공간측정에 가장 효과적인 방법을 알아보는 것이다. 재료 및 방법. 건강한 자연치열을 가진 성인 20명(남자 10명, 여자 10명)을 피실험자로 선정하였다. 임상경험 5년 이상의 치과의사 1인이 치실 방법, 셀룰로이드 스트립 방법, 금속 스트립 방법을 이용하여 인접면 접촉을 평가하였다. 치실 방법으로 수집된 자료는 Mann-Whitney U test를 사용하여 95% 신뢰수준 하에서 R 프로그램을 이용하여 분석하였다. 그리고 치실을 이용한 인접면 접촉 평가에 셀룰로이드 스트립과 금속 스트립을 사용한 인접면 접촉의 평가를 비교하였다. 결과. 건강한 치열에서 약 80%에서만 적절한 접촉강도를 유지하고 있었으며, 전치부보다 구치부가 더 적절하게 유지하고 있었다(P < .05). 성별에 따른 접촉강도는 전치부에서는 남성이, 구치부에서는 여성이 적절한 접촉을 하는 것으로 나타났다(P < .05). 일치성 척도인 카파 지수(Kappa index)를 이용하여 치실에서 얻은 결과에 대한 셀룰로이드 스트립과 금속 스트립 실험 결과 간의 일치성을 분석한 결과, 셀룰로이드 스트립을 사용하는 것이 금속 스트립을 사용하는 것보다 더 유리한 것으로 나타났다. 결론. 건강한 치열에서 약 80%에서만 적절한 접촉강도를 유지하고 있었으며, 인접면 접촉의 평가에서 다양한 두께의 셀룰로이드 스트립을 사용한다면 보다 정확한 공간 측정의 가능성이 있을 것으로 생각된다.

• 신재생에너지
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• 제1권1호
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• pp.37-43
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• 2005

High-efficiency silicon solar cells have potential applications on mobile electronics and electrical vehicles. The fabrication processes of the high efficiency cells necessitate com placated fabrication precesses and expensive materials. Ti/Pd/Ag metal contact has been used only for limited area In spite of good stability and low contact resistance because of Its expensive material cost and precesses. Screen printed contact formed by Ag paste causes a low fill factor and a high shading loss of commercial solar cells because of high contact resistance and a low aspect ratio. Low cost Ni/Cu metal contact has been formed by using a low cost electroless and electroplating. Nickel silicide formation at the interface enhances stability and reduces the contact resistance resulting In an energy conversion efficiency of $20.2\%\;on\;0.50{\Omega}cm$ FZ wafer. Tapered contact structure has been applied to large area solar cells with $6.7\times6.7cm^2$ in order to reduce power losses by the front contact The tapered front metal contact Is easily formed by the electroplating technique producing $45cm^2$ solar cells with an efficiency of $21.4\%$ on $21.4\%\;on\;2{\Omega}cm$ FZ wafer.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.179.2-179.2
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• 2014

Carbon nanotubes (CNT)-metal contacts play an important role in nanoelectronics applications such as field-effect transistor (FET) devices. Using Al and (10,0) CNT, we have recently showed that the CNT-metal contacts mediated via topological defects within CNT exhibits intrinsically low contact resistance, thanks to the preservation of the sp2 bonding network at the metal-CNT contacts.[1] It is well-established that metals with good wetting property such as Pd consistently yield good contacts to both metallic and semiconducting CNTs. In this work, the electronic and charge transport properties of the interfaces between capped CNT and Pd will be investigated based on first-principles computations and compared with previous results obtained for the Al electrodes.

• The Journal of Advanced Prosthodontics
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• 제7권2호
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• pp.172-177
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• 2015

PURPOSE. The purpose of this study was to evaluate cell toxicity due to ion release caused by galvanic corrosion as a result of contact between base metal and titanium. MATERIALS AND METHODS. It was hypothesized that Nickel (Ni)-Chromium (Cr) alloys with different compositions possess different corrosion resistances when contacted with titanium abutment, and therefore in this study, specimens ($10{\times}10{\times}1.5mm$) were fabricated using commercial pure titanium and 3 different types of Ni-Cr alloys (T3, Tilite, Bella bond plus) commonly used for metal ceramic restorations. The specimens were divided into 6 groups according to the composition of Ni-Cr alloy and contact with titanium. The experimental groups were in direct contact with titanium and the control groups were not. After the samples were immersed in the culture medium - Dulbecco's modified Eagle's medium[DMEM] for 48 hours, the released metal ions were detected using inductively coupled plasma mass spectrometer (ICP-MS) and analyzed by the Kruskal-Wallis and Mann-Whitney test (P<.05). Mouse L-929 fibroblast cells were used for cell toxicity evaluation. The cell toxicity of specimens was measured by the 3-{4,5-dimethylthiazol-2yl}-2,5-diphenyltetrazolium bromide (MTT) test. Results of MTT assay were statistically analyzed by the two-way ANOVA test (P<.05). Post-hoc multiple comparisons were conducted using Tukey's tests. RESULTS. The amount of metal ions released by galvanic corrosion due to contact between the base metal alloy and titanium was increased in all of the specimens. In the cytotoxicity test, the two-way ANOVA showed a significant effect of the alloy type and galvanic corrosion for cytotoxicity (P<.001). The relative cell growth rate (RGR) was decreased further on the groups in contact with titanium (P<.05). CONCLUSION. The release of metal ions was increased by galvanic corrosion due to contact between base metal and titanium, and it can cause adverse effects on the tissue around the implant by inducing cytotoxicity.

• 한국재료학회지
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• 제20권8호
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• pp.401-407
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• 2010

We studied the influence of different types of metal electrodes on the performance of solution-processed zinc tin oxide (ZTO) thin-film transistors. The ZTO thin-film was obtained by spin-coating the sol-gel solution made from zinc acetate and tin acetate dissolved in 2-methoxyethanol. Various metals, Al, Au, Ag and Cu, were used to make contacts with the solution-deposited ZTO layers by selective deposition through a metal shadow mask. Contact resistance between the metal electrode and the semiconductor was obtained by a transmission line method (TLM). The device based on an Al electrode exhibited superior performance as compared to those based on other metals. Kelvin probe force microscopy (KPFM) allowed us to measure the work function of the oxide semiconductor to understand the variation of the device performance as a function of the types metal electrode. The solution-processed ZTO contained nanopores that resulted from the burnout of the organic species during the annealing. This different surface structure associated with the solution-processed ZTO gave a rise to a different work function value as compared to the vacuum-deposited counterpart. More oxygen could be adsorbed on the nanoporous solution-processed ZTO with large accessible surface areas, which increased its work function. This observation explained why the solution-processed ZTO makes an ohmic contact with the Al electrode.