• Corrosion Science and Technology
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• v.16 no.6
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• pp.317-327
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• 2017

The change in the oxidation behavior of three types of B-added ultrahigh strength martensitic steels containing Ti and Nb induced by applying constant cathodic current was investigated. In a 3% NaCl+0.3% $NH_4SCN$ solution, the overall polarization behavior of the three alloys was similar, and degradation of the oxide film was observed in the three alloys after applying constant cathodic current. A significant increase in the anodic current density was observed in the Nb-added alloy, while it was diminished in the Ti-added alloy. Both Ti and Nb alloying decreased the hydrogen overpotential by forming NbC and TiC particles. In addition, the thickest oxide film was formed on the Ti-added alloy, but the addition of Nb decreased the film thickness. Therefore, it was concluded that the remarkable increase in the anodic current density of Nb-added alloy induced by applying constant cathodic current density was attributed to the formation of the thinnest oxide film less protective to hydrogen absorption, and the addition of Ti effectively blocked the hydrogen absorption by forming TiC particles and a relatively thick oxide film.

• Journal of the Korean Electrochemical Society
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• v.13 no.2
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• pp.138-144
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• 2010

In order to investigate the electrochemical propertied of titanium electrode for electrolysis, manganese oxide was electrodeposited on surface of mesh titanium by pulse voltammetry. The morphological changes and impedance results of manganese oxide electrodeposited electrode were analyzed by SEM and EDX. The size of electrodeposited manganese oxide on mesh titanium was increased with first cycle pulse time increase, and approximately 100 non-uniform manganese oxide was grown at 10 ms pulse polarization time. Charge transfer resistance($R_{ct}$) of near the overpotential was analyzed by EIS measurement and the feasibility of prepared electrode was evaluated by the overpotential calculated from Tafel plots.

• Journal of the Korean institute of surface engineering
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• v.18 no.3
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• pp.125-133
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• 1985

About 1 mm thick nickel electrodeposits were obtained from nickel sulphamate baths at 40 to 60$^{\circ}C$ over the range of current densities form 5 to 25 A/$dm^2$. Deposits from above about 1.2V of cathode overpotential had randomly distributed fine grains due to a higher nucleation rate and hence had a high hardness. A deposit obtained at 0.63 V had the [110] orientation with a field oriented fine structure which yield a relatively high hardness. Deposite obtained at the intermediate overpotentials showed the [100] orientation with coarse field oriented structure whose column width tended to decrease with increasing cathode overpotential, which, in turn, gave rise to an increase in hardness. Residual stresses of the deposits measured by X-ray technique were mostly tensile but did not exceed 80 MPa, and were occasionally very small compressive. The cathode current efficiency was above 90% in all the electrolysis conditions, whereas the anode current efficiency varied from 50 to 90% with current density, bath temperature and nickel chloride concentration, among which the chloride was the most influential.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.2
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• pp.96-101
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• 2021

Developing effective and earth-abundant electrocatalyst for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is critical for the commercialization of a water splitting system. In particular, the overpotential of the OER is relatively higher than the HER, and thus, it is considered that one of the important methods to enhance the performance of the electrocatalyst is to reduce the overpotential of the OER. We report effects of incorporation of metalloid into Ni(OH)2 microcrystal on electrocatalytic activities. In this study, Te incorporated Ni(OH)2 (��Te-Ni(OH)2) were grown on three-dimensional porous NF by a facile solvothermal method with �� = 1, 3 and 5. Homogeneous microplate structure on the NF was clearly observed for the Ni(OH)2/NF and ��Te-Ni(OH)2/NF samples. However, irregular and collapsed nanostructures were found on the surface of nickel foam when Te precursor ratio is (��) over 3. Electrocatalytic OER properties were analysed by Linear sweep voltammetry (LSV) and Electrochemical impedance spectroscopy (EIS). The amount of Te incorporation used in the electrocatalytic reaction was found to play a crucial role in improving catalytic activity. The optimum Te amount (��) introduced into the Ni(OH)2/NF was discussed with respect to their OER performance.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.71-75
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• 2022

In this research, Fe-Ni alloy films were electrodeposited on stainless steel (SS304 and SS430) and Ti plates to investigate the effects of surface conditions of cathode on deposits. The Ti plates were electropolished in 3 M H₂SO₄-methanol electrolytes at various conditions before electrodeposition, and unpolished Ti and the optimized specimen, polished at 10 V for 8 min, were used as cathode. The anomalous codeposition, the phenomenon which more active Fe is reduced preferentially, occurred on all substrate, however, there were differences in composition of all deposits. As the results of potential monitoring during electrodeposition, it was confirmed that the larger overpotential was applied to the deposition cell when using Ti cathode, leading to high Fe content of deposits from unpolished Ti due to increase in nucleation of Fe. Also, it was founded that the polished Ti can reduced deposition overpotential.

• Journal of Aerospace System Engineering
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• v.1 no.2
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• pp.21-26
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• 2007

DMFC(Direct Methanol Fuel Cell) has been considered as an attractive option to produce electric power in many application. In this study, in order to estimate the effects of the methanol concentration, wind velocity and temperature on the performance of DMFC, a physical prototype of DMFC was designed and manufactured, and the stack voltage of DMFC was measured during the operation of DMFC. Expecially, the experimental results showed that a low stack temperature, a low wind velocity and an excess methanol concentration lead to the increase of the time to reach the maximum stack voltage.

• Journal of Electrochemical Science and Technology
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• v.8 no.4
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• pp.307-313
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• 2017

In this paper we report an electrochemical sensor based on ZnO-functionalized graphene oxide nanocomposite (ZnO-GO) for the sensitive determination of the cabergoline. Cabergoline electrochemical behaviors were investigated by cyclic voltammetry (CV), chronoamperometry (CHA) and differential pulse voltammetry (DPV). The modified electrode shows electrocatalytic activity toward cabergoline oxidation in phosphate buffer solution (PBS) (pH 7.0) with a reduction of the overpotential of about 180 mV and an increase in peak current. The DPV data showed that the obtained anodic peak currents were linearly dependent on the cabergoline concentrations in the range of $1.0-200.0{\mu}M$, with the detection limit of $0.45{\mu}M$. The prepared electrode was successfully applied for the determination of cabergoline in real samples.

• Journal of the Korean Ceramic Society
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• v.29 no.5
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• pp.377-382
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• 1992

For the development of solid oxide fuel cell the joined interface formation between perovskite oxygen electrode and YSZ solid electrolyte is emphasized in the aspect of reducing the undisirable overpotential. The diffusion couple of LaMnO3 and YSZ was prepared by hot pressing at 130$0^{\circ}C$ in the flow of oxygen gas. The high temperature solid state reaction mechanism between LaMnO3 and YSZ is discussed on the basis of the cation composition profile through EDX analysis. The cation components in perovskite compound diffuse considerably into YSZ, while cations of YSZ diffuse little into perovskite.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.490-493
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• 2006

The results of simulation of direct methane fuel cell fed with liquid-state methanol feed are shown. This numerical process is based on mass and current conservation equations. The results showed that over low current density $(<200mA/cm^2)$ IV polarization curve was well-presented compared to experimental result. Methanol fed from anodic side moved into cathodic side through electrolyte membrane and the pressure near cathode electrode increased according to amount of methanol crossover and production of water. Besides change of overpotential on each el electrode were checked by x-axis.

• Journal of the Korean Society of Safety
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• v.8 no.3
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• pp.56-63
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• 1993

In this study the ultrasound which has the properties of mixing, surface cleaning effect, increasing of the effective reaction surface area and increasing of the effective collision frequency, was used to enhance the recovering efficiency of Cu from the Cu-ion containning waste water. The ultrasonic reactor used in this study was dsigned and constructed for improving the disadvantage of the existing ultrasonic reactor From the experimental result and its analysis. we obtained following conclusions. 1. The ultrasound increased the rate of electrochemical deposition to 582.2% in maximum at the Condition of 0.1M-CuSO$_4$and 2.1V-overpotential. 2. This study gave the possibility of the scale-up of ultrasonic reactor and In particular, ultrasonic reactor would be effective in treatment of waste water contains a low concentration of Cu ion.