• Transactions of the Korean hydrogen and new energy society
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• v.10 no.2
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• pp.141-149
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• 1999

Recently the Ni/MH secondary battery has been studied extensively to achieve higher energy density, longer cycle life and faster charging-discharging rate etc. In this work, the electrode properties of $(LM)Ni_{4.49}Co_{0.1}Mn_{0.205}Al_{0.205}$ alloy and $Ti_{0.6}Zr_{0.4}V_{0.6}Ni_{1.4}$ alloy with addition of Pd were investigated. These alloys did not show any change in XRD pattern by Pd addition. As Pd was added as alloy element, the activation behavior was not affected significantly in both $AB_2$ type and $AB_5$ type electrodes and, On charging and discharging in high current density, Discharge capacity with increasing of Pd content was more decreased. But cycle life was showed increasing. Especially the electrode of $Ti_{0.6}Zr_{0.4}V_{0.6}Ni_{1.4}+0.5wt%$ Pd alloy was not almost decreased discharge capacity for 400cycles.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.796-801
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• 1992

An empirical Lewis basicity, DN, for eight mixed methanol solvents has been measured by the solvatochromic behavior of the [Cu(tmen)(acac)]$CIO_4$. The change of DN in mixed methanol solvents is not correlated with composition of the mixtures and divided into three groups: (1) dipolar aprotic solvents contribute mainly to the solvation of solute (MeOH-DMSO, MeOH-PY, MeOH-DMF), (2) two components of mixture contribute equally to the solvation of solute (MeOH-MeCN, MeOH-dioxane, MeOH-AC) and (3) methanol contributes entirely to the solvation of solute (MeOH-DCE, MeOH-TCE). The relationship between DN and Kamlet-Taft's $B_{KT}$ for mixed methanol solvents was found to agree well. These DN values also were a useful factor to analysis of reactivity for mixed methanol solvents.

• Clean Technology
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• v.20 no.1
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• pp.28-34
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• 2014

In this study, we synthesized $TiO_2$ supports with nanosized crystalline structure by solvothermal method and prepared $TiO_2$ supported Pd-Cu catalysts. It was shown that the crystalline size of $TiO_2$ support in the catalyst influenced on the catalytic activity of nitrate reduction in water. The catalyst with the smaller crystalline size of $TiO_2$ support presented faster nitrate reduction rate, but had low nitrogen selectivity due to high pH environment of reaction medium during the reaction. Through injection of carbon dioxide as a pH buffer, the nitrogen selectivity increased by about 60%. Furthermore, we investigated that the relationships between the catalytic performance and the physicochemical properties of the prepared catalysts characterized by $N_2$ adsoprtion-desorption, X-ray diffraction (XRD), $H_2$-temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.1
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• pp.88-97
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• 1996

The metallization is the key to determining cell costs, cell performance, and system reliability. Screen printing technology suffers from several limitations affecting mainly the front grid. The buried contact solar cell (BCSC) was specifically desinged to be compatible with low cost, mass production techniques and avoid the conventional metallization problem. By using electroless plating technique, we performed this metallization inexpensively and reliably. This paper presents the details of the optimization procedure of metallization schemes on laser grooved cell surfaces. Commercially available Ni, Cu and Ag plating solutions were applied for the cell metallization. The application of those solutions on the buried contact front metallization has resulted in an cell efficiency of 18.8%. The cell parameters are an open circuit voltage of 651 mV, short circuit current density of 37.1 mA/$\textrm{cm}^2$, and fill factor of 77.8 %. The efficiency of over 18 % was achieved in the above 90% of the batch.

• Corrosion Science and Technology
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• v.19 no.4
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• pp.211-223
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• 2020

The external corrosion of buried piping can be controlled using both coating and cathodic protection. Several factors are involved in the damage and deterioration of the coating on pipes. There are many detection methods for coating defects on pipes and the direct current voltage gradient (DCVG) method is one of the most powerful methods. However, the detection reliability of DCVG can be affected by interferences such as stray current, metal objects connected to rectifiers, and copper grids. Therefore, this study focused on the interference effects of rectifiers and a copper grid on the reliability of coating flaw detection. As the length of the interference pipe connected to the rectifier increased, the reliability decreased. In contrast, as the distance between the pipe and the copper grid increased, the reliability of the coating flaw detection increased. The detection results produced by the DCVG method were discussed using current and potential simulations for a pipe with a rectifier and copper grid interference in the soil.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.12
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• pp.1373-1379
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• 2012

The interaction of magnetic field in the frequency range of 9~150 kHz radiating from a railway system with wireless systems has been the cause of radio frequency interference. In this paper, the equivalent circuit model of the RFI noise is proposed through source and transfer path analysis, and it is confirmed that the switching noise of several kHz that occurs a vehicle traction drive system and a substation is radiated by forming the loop circuit with a feeder line by a rolling stock. And the validity of the proposed equivalent circuit model is verified by analyzing the effects of RC banks installed in the real railway between Guri and Guksu stations, the RFI noise can be effectively mitigated by loading suitable capacitance between rail and feeding line.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.80-80
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• 2011

세계 기후 변화와 불안정한 유가 변화에 대응하고 국내산업의 저탄소 녹색성장을 위해 신재생에너지 개발이 활발하게 이루어지고 있다. 해양에너지 중에서 조류발전은 대규모 댐을 건설할 필요가 없어 비용이 적게 소요되고 특히 날씨 변화나 계절에 관계가 없고, 발전량이 예측 가능하므로 신뢰성 있는 에너지원으로 적용이 가능하다. 조류발전기 블레이드에 폴리머계 복합재료와 스테인리스강이 대부분인데, 이 재료는 특정 회사에서만 제작 가능하며, 충격에 약하고, 균열전파 속도가 빠르며, 대단히 고가이며, 수입에 의존하고 있는 실정이다. 이러한 조류발전에 사용되는 블레이드는 가혹한 부식, 캐비테이션 그리고 침식환경에 노출되어 있어 내구성이 우수한 제품개발이 대단히 중요하며, 조류발전 블레이드를 동합금으로 제작시, 내식성이 뛰어나며 구리의 특성상 해양생물 서식을 방지할 수 있고, 내캐비테이션 특성, 내구성, 가공성 및 유지보수가 용이한 장점이 있다. 이러한 동합금에 WC-27NiCr와 WC-10Co4Cr를 초고속 화염용사(HVOF)를 이용하여 코팅층의 캐비테이션 특성 및 전기화학적 거동을 연구하였다. 본 연구에서는 조류발전용 블레이드의 재료로 사용하려는 동합금에 WC-27NiCr와 WC-10Co4Cr이 용사코팅된 시험편을 사용하였다. 다채널 부식시험기인 WonA-tech WMPG-1000을 이용하여, 자연전위를 측정하였으며, 분극실험은 자체 제작한 홀더를 사용하여 $0.3318cm^2$를 노출 시켜 실험하였다. 기준전극은 은/염화은 전극을, 대극은 백금 전극을 사용하였다. 양분극과 음분극 실험을 통해 개로전위에서의 부식거동을 확인하였고, 정전위 실험도 실시하였다. 실험 종료 후 3D현미경 및 전자주사현미경(SEM)을 사용하여 코팅층 표면의 손상거동을 관찰하였다. 캐비테이션 실험은 ASTM-G32 규정에 의거하여 압전효과를 용한 진동발생 장치(RB 111-CE)를 사용하였다. 수조는 전기화학적 부식의 영향을 고려하여 아크릴로 제작하였고, 시험편은 실험장비에 맞게 파인커팅머신을 이용하여 $20mm{\times}20mm$로 절단하여 사용하였으며 혼과 대향하도록 하여 1mm 간격을 두어 실험하였다. 실험 실시 전, 미소전자저울을 사용하여 무게감소량을 측정하였으며 표면관찰을 통하여 캐비테이션 거동을 관찰하였다.

• Journal of Energy Engineering
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• v.24 no.1
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• pp.78-87
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• 2015

Focusing effect of a metallic layer in a severe accident depending on the aspect ratios and cooling conditions of top plate and side wall was investigated. Experiments were carried out for Rayleigh numbers and aspect ratio in the range of $8.49{\times}10^7{\sim}5.43{\times}10^9$, 0.135~0.541 respectively. In order to achieve high Rayleigh numbers, the heat transfer experiments were replaced by mass transfer experiments based on the heat and mass transfer analogy. A sulfuric acid-copper sulfate ($H_2SO4-CuSO_4$) electroplating system was adopted as the mass transfer system. The experimental results agreed well with the Rayleigh-Benard natural convection correlations of Dropkin and Somerscales and Globe and Dropkin. When compared with the standard Rayleigh-Benard problem, the cooling by the side wall is even higher than the top. For a shorter height, the interaction between the heated and cooled plumes increases due to decrease of the height. Thus, the heat transfer increases.

• Economic and Environmental Geology
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• v.38 no.4 s.173
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• pp.421-434
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• 2005

Abstract Based onthe characteristics of Carlin-type gold deposit in Nevada district, a potential in Korea is evaluated to the Yemi area where is structurally controlled by folds and trust fault. The fault of high angles are combined with a more permeable rocks such as the Yemi breccia and laminated silty limestone. The pattern of enrichment factors for Tl, Sb, As, Ag, Pb, Zn, Cu, Mo and W of limestones in the southern area are geochemically similar with those reported from the Carlin-type Bold deposit. Moreover, the oxygen and carbon isotopes show a hydrothermal alteration is widely developed in this area. According to the result of geophysical interpretation, stable isotope, alteration mineralogy, geochemical study, and geological structure, this mineralized zone may be extended to the M direction, so a detailed systematic exploration is required to identify this alteration zone.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.132-132
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• 2000

Cu는 Al에 비하여 낮은 저항(1.8 $\mu$$\Omega$-cm)과 높은 EM 저항성을 가지고 있어 미래의 고속 ULSI 배선물질로 그 중요성이 더욱 증가되고 있으며, 현재까지 많은 연구가 진행되고 있다. 따라서, 본 논문에서는 이러한 방법들을 고려하여 CVD Cu의 문제점인 낮은 성장률의 개선과 Cu 박막의 특성을 향상하고자 수소 플라즈마 공정을 이용하여 plasma 전처리가 초기 Cu 핵생성에 미치는 영향에 대하여 연구하였다. 본 실험에 사용된 장비는 Cu RPCVD/MOCVD이다. 초기 Cu 핵의 생성에 있어서의 수소 플라즈마의 효과를 조사하기 위하여 다음과 같은 3가지의 방법으로 행하였다. 첫 번째는 Cu 박막 형성에서 플라즈마를 사용하지 않은 방법, 두 번째는 플라즈마 전처리공정을 행한 뒤, Cu 박막 증착시 플라즈마는 사용하지 않은 방법, 세 번재는 플라즈마 전처리공저을 행한 뒤 Cu 증착시에도 플라즈마를 사용한 방법이다. 이 세가지 방법의 핵생성 차이를 분석하기 위해서 각각 10초, 20초, 40초 증착시킨 후 grain의 크기와 개수를 비교하였다. 또한 플라즈마의 power에 따른 Cu 핵생성율도 조사하였다. 수소 전처리동안 working pressure는 10분 동안 1 torr로 유지되었으며 substrate의 온도는 20$0^{\circ}C$, r.f.power는 100watt로 설정하였다. Cu RPCVD의 증착조건은 r.f.power는 10watt, substrate의 온도는 20$0^{\circ}C$, gas pressure는 1 torr, Ar carrier gas는 50sccm, hydrogen processing gas는 100sccm, bubbler 온도는 4$0^{\circ}C$, gas line의 온돈느 6$0^{\circ}C$, shower head의 온도는 $65^{\circ}C$로 설정하였다. 증착된 Cu 박막은 SEM, XRD, AFM를 통해 제작된 박막의 특성을 비교.분석하였다. 초기 plasma 처리를 한 경우에는 그림 1에서와 같이 현저히 증가한 초기 구리 입자들이 관측되었으며, 이는 도상 표면에 활성화된 catalytic site의 증가에 기인한다고 보여진다. 이러한 특성은 Cu films의 성장률을 향상시키고, 또한 voids를 줄여 전기적 성질 및 surface morphology를 향상시키는 것으로 나타났다.