• Current Photovoltaic Research
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• 제2권1호
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• pp.18-27
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• 2014

Dye-sensitized solar cells (DSSCs), developed two decades ago, are considered to be an attractive technology among various photovoltaic devices because of their low cost, accessible dye chemistry, ease of fabrication, high power conversion efficiency, and environmentally friendly nature. A typical DSSCs consists of a dye-coated $TiO_2$ photoanode, a redox electrolyte, and a platinum (Pt)-coated fluorine-doped tin oxide (FTO) counter electrode. Among them, redox electrolytes have proven to be extremely important in improving the performance of DSSCs. Due to many drawbacks of iodide electrolytes, many research groups have paid more attention to seeking other alternative electrolyte systems. With regard to this, one-electron outer sphere redox shuttles based on cobalt complexes have shown promising results: In 2014, porphyrin dye (SM315) with the cobalt (II/III) redox couple exhibited a power conversion efficiency of 13% in DSSCs. In this review, we will provide an overview and perspectives of cobalt redox electrolytes in DSSCs.

• 한국재료학회지
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• 제13권11호
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• pp.711-716
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• 2003

Gate length, height, and silicide thickness have all been shrinking linearly as device density has progressively increased over the years. We investigated the effect of the cobalt diffusion during the silicide formation process on the 60$\AA$-thick gate oxide lying underneath the Ti/Co and Co/Ti bilayers. We prepared four different cobalt silicides, which have similar sheet resistance, made from the film structure of Co/Ti(interlayer), and Ti(capping layer)/Co, and peformed the current-voltage, time-to-break down, and capacitance-voltage measurements. Our result revealed that the cobalt silicide process without the Ti capping layer allowed cobalt atoms to diffuse into the upper interface of gate oxides. We propose that 100$\AA$-thick titanium interlayer may lessen the diffusion of cobalt to gate oxides in 1500-$\AA$ height polysilicon gates.

• 한국전기전자재료학회논문지
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• 제18권10호
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• pp.896-901
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• 2005

The microstructure and electrical properties of praseodymium-based zinc oxide varistors were investigated at various cobalt oxide contents in the range of $0.5{\~}5.0 mol\%$. The ceramic density increased in the range of $5.25{\~}5.55 g/cm^3$ with increasing cobalt oxide content. The varistor doped with cobalt oxide of $1.0 mol\%$ exhibited the highest nonlinearity, with 66.6 in nonlinear exponent and 1.2 $\mu$A in leakage current. The donor concentration, density of interface states, and tamer height were in the range of $(1.06{\~}1.69){\times}10^{18}/cm^3$, $(3.11 {\~}3.56){\times}10^{12}/cm^2$, and 0.80${\~}$1.07 eV, respectively.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1146-1147
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• 2006

Diamond segments were fabricated by cold pressing and sintering under pressure at the temperature up to $750^{\circ}C$. Based on the results of this investigation, it can be concluded that the segments containing 39wt.% cobalt in the matrix material have the highest bending strength at a fracture probability of 50 % due to the weibull distribution method. According to the weibull statistics, it was also determined that the transverse rupture strength was the best for 39 wt.% cobalt ratio in the matrix material for the fracture probability when the other variables are the same.

• 대한치과교정학회지
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• 제19권1호
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• pp.245-256
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• 1989

Translational movement along an arch wire requires sufficient force to overcome frictional forces between bracket and arch wire. The orthodontist must appreciate the importance of friction in this process, and study out the influencing factors on the level of friction. The purpose of this study was to evaluate the effect of artificial saliva on frictional resistances generated between the bracket and arch wire. Independent variables of this study were arch wire material, angulation and environment. Static frictional forces of cobalt-chromium, heat-treated cobalt-chromium, beta-titanium, stainless steel wires were measured under non-angulated dry, angulated dry, non-angulated saliva, angulated saliva conditions. The results were as follows: 1. Stainless steel wires showed lower friction values in non-angulated dry condition, and heat-treated cobalt-chromium wires showed higher friction values in angulated dry condition. Higher friction values were showed in order of cobalt-chromium. stainless steel, heat-treated cobalt-chromium and beta-titanium wires in non-angulated saliva condition. and were showed in order of stainless steel, cobalt-chromium, heat-treated cobalt-chromium, beta-titanium wires in angulated saliva condition. 2. Angulation increased friction for stainless steel wires under dry condition. 3. Artificial saliva decreased friction for cobalt-chromium wires and increased friction for stainless steel wires under non-angulated condition. 4. Artificial saliva decreased friction for all wires except beta-titanium wires under angulated condition. 5. Regardless of angulation or environment. heat-treated cobalt-chromium and beta-titanium wires showed higher friction values, and stainless steel wires showed lower friction values.

• 한국세라믹학회지
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• 제45권6호
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• pp.368-373
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• 2008

An electrode for supercapacitor using 3-dimensional porous nickel foam as a current collector and cobalt oxide as an active material was prepared and characterized in terms of morphology observation, crystalline property analysis, and the investigation of electrochemical property. The electrode surface showed that the cobalt oxide was homogeneously coated as the crystalline phase of $Co_3O_4$. Cyclic voltammetry for the $Co_3O_4$/nickel foam electrode exhibited higher specific capacitance values (445 F/g at 10 mV/s and 350 F/g at 200 mV/s) and excellent capacitance retention ratio (99% after $10^4$ cycles). It was proved that the nickel foam substrate played the roles in reducing the interfacial resistance with cobalt oxide and in improving the electrode density by embedding greater amount of cobalt oxide within it.

• 공업화학
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• 제31권4호
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• pp.423-428
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• 2020

이 연구에서는 합성가스를 유일한 탄소원으로 사용하는 Clostridium autoethanogenum 배양에서 배지 성분 중 금속이온의 농도가 균주 성장과 대사산물 생산에 미치는 영향을 조사하였다. C. autoethanogenum 배양에 사용되는 기본 배지구성 성분의 금속이온 종류 중 molybdenum, nickel, cobalt를 조사 대상으로 선정하여 이 성분들의 농도를 달리하였을 때 균주 성장과 에탄올, 아세트산 생산에 미치는 영향을 확인하였다. Molybdenum은 0, 0.001, 0.01, 0.1 g/L농도를 시험하였으며 0.001 g/L에서 에탄올 생산량이 약간 증가하는 경향을 보였지만 시험한 농도 범위 내에서 뚜렷한 영향이 관찰되지 않았다. Nickel은 0, 0.001, 0.01, 0.1 g/L의 농도 범위에서 균주 성장과 에탄올 생산에 미치는 영향을 관찰하였으며, 0.01 g/L 농도에서 에탄올 생산농도가 기본 배지 농도인 0.1 g/L에서보다 26% 증가되는 것을 확인하였다. Cobalt는 0, 0.018, 0.18, 1.8 g/L 농도 범위에서 균주 성장과 에탄올 생산에 미치는 영향을 분석하였으며, 기본 배지 조건인 0.18 g/L의 이상의 농도에서는 균주 성장이 약간 저해되는 현상이 관찰되었다. 결과적으로 연구에 사용된 세 가지 금속이온 성분 중 cobalt는 배지 내 성분 농도에 따른 에탄올 생산농도 향상을 이루지 못하였으나, molybdenum, nickel은 기본 배지 내 일반적인 농도의 1/10을 사용함으로써 에탄올 생산농도 향상을 이룰 수 있었다.

• 대한금속재료학회지
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• 제46권4호
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• pp.209-216
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• 2008

Super austenitic stainless steels shows the high PRE (Pitting Resistance Equivalent) number and the good corrosion resistance. This work controlled the Co contents in Fe-31Cr-1.7Mo-27Ni-0.25N alloys to elucidate the effect of cobalt contents on the biocompatibility and corrosion resistance. Increasing Co contents, the hardness of the annealed alloys tends to be reduced. In aged alloys, cobalt decreased the increments of hardness by aging treatment. Cobalt decreased the critical pitting temperature (CPT) in 6% $FeCl_3$ + 1% HCl solution, but improved the anodic polarization behavior in Hanks' balanced salt solution and artificial saliva solution. Repassivation rate in artificial body solutions was improved by increasing cobalt contents, but didn't show the linear relationship to PRE number of the alloys. The experimental alloys showed the non-cytotoxicity because of its high corrosion resistance.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3227-3232
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• 2013

A novel Cu-Co-O composite nanocatalyst was designed and prepared for the ozonation of phenol. A synergistic effect of copper and cobalt was observed over the Cu-Co-O composite nanocatalyst, which showed higher activity than either copper or cobalt oxide alone. In addition, the Cu-Co-O composite revealed good activity in a wide initial pH range (4.11-8.05) of water. The fine dispersion of cobalt on the surface of copper oxide boosted the interaction between catalyst and ozone, and the surface Lewis acid sites on the Cu-Co-O composite were determined as the active sites. The Raman spectroscopy also proved that the Cu-Co-O composite was quite sensitive to the ozone. The trivalent cobalt in the Cu-Co-O composite was proposed as the valid state.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2003년도 international symposium on advanced powder metallurgy
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• pp.56-56
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• 2003