• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.69-69
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• 2009

In other to progress better crystallization transition and long phase-transformation data of phase-change memory (PRAM), we investigated about the effect of Sb doping and Ag ions percolating into Ge-Se-Te phase-change material. Doped Sb concentrations was determined each of 10 wt%, 20 wt% and 30 wt%. As the Sb-doping concentration was increased, the resistivity decreased and the crystallization temperature increased. Ionization of Ag was progressed by DPSS laser (532 nm) for 1 hour. The resistivity was more decreased and the crystallization temperature was more increased in case of adding Ag layer under Sh-(Ge-Se-Te) thin film. At the every condition of thin films included Ag layer more stable states were indicated compare with just Sh-doped Ge-Se-Te thin films.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1740-1745
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• 2004

A simplified resistor network model for electrical and mass transport in anode-supported planar solid oxide fuel cell (SOFC) was constructed in order to investigate the effect of interconnect rib geometry on the cell performance. For accurate potential calculation, activation and concentration over-potentials at the electrode/electrolyte interfaces were fully considered in this calculation. When contact resistance was not considered, the optimum interconnect rib length were calculated to be $0.1{\sim}0.2$ mm for 2 mm half unit cell for given operation conditions and properties. However, with realistic contact resistance, the interconnect rib length should be increased to provide larger contact area and thus to obtain better performance.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.508-512
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• 2004

An ultra-sharp tungsten electrode for field emission was manufactured by using an electrochemical etching method, and its beam characteristics were investigated. KOH and NaOH were the electrolytes used in this research, and the taper length of the tip varied form 150 $\mu\textrm{m}$ to 250 $\mu\textrm{m}$ according to the applied voltage and the concentration of the electrolyte. The electron-beam stability was measured to be within 5% for a total emission current of 5 ${\mu}\textrm{A}$ during 4 hours of operation, and the Ignition voltages were found to be ∼300 V. The tip radius was experimentally found to be 250${\AA}$ from a linear fitting of Fowler-Nordheim plots, which was in remarkably good agreement with that of the image size from scanning ion-microscopy.

• Journal of Sensor Science and Technology
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• v.16 no.2
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• pp.115-119
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• 2007

We report electrokinetic streaming potential detection in a microchannel. Streaming potential, one of the representative electrokinetic phenomena, becomes noticeable either when the channel size reduces or when the concentration of electrolyte reduces. We suggest a triangular-shaped microchannel to enhance streaming potential. The triangular-shaped microchannel shows better performance than the straight one in terms of streaming potential. Couple of possible methods to enhance streaming potential is also discussed. Moreover, this type of channel and phenomenon can be applied to biological sensor application and energy transduction.

• Toxicological Research
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• v.24 no.1
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• pp.23-28
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• 2008

Voltammetric analysis of mercury ions was developed using paste electrodes (PEs) with DNA and carbon nanotube mixed electrodes. The optimized analytical results of the cyclic voltammetry (CV) of the $1{\sim}14ng\;L^{-1}Hg(II)$ concentration and the square wave (SW) stripping voltammetry of the $1{\sim}12ng\;L^{-1}Hg(II)$ working range within an accumulation time of 400 seconds were obtained in 0.1 M $NH_4H_2PO_4$ electrolyte solutions of pH 4.0. For the relative standard deviations of the $1ng\;L^{-1}Hg(II)$, which were observed at 0.078% (n = 15) at the optimum conditions, the low detection limit (S/N) was pegged at $0.2ng\;L^{-1}(7.37{\times}10^{-13}M)$ for Hg(II). The results can be applied to assays in biological fish kidneys and wastewater samples.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.163-169
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• 2005

Micro hole is ode of basic elements for micro device or micro parts. Micro electrochemical machining (ECM) can be applied to the machining of micro holes less than 50 ${\mu}m$ in diameter, which it is not easy to apply other techniques to. For the machining of passivating metals such as stainless steel, machining conditions should be chosen carefully to prevent a passive layer. The machining conditions also affect the machining resolution, In this paper, machining characteristics of micro ECM were investigated according to machining conditions such as electrolyte concentration and pulse conditions. From the investigation, optimal machining conditions were suggested for micro ECM of stainless steel.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1202-1205
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• 2005

Micro hole is one of basic elements for micro device or micro parts. By micro ECM, micro holes less than $50\mu{m}$ in diameter can be machined easily. Machining characteristics of micro ECM were investigated according to machining conditions such as electrolyte concentration and pulse conditions. From the investigation, optimal machining conditions were suggested for micro ECM of stainless steel. For the micro machining with high resolution, the change of machining gap should be predicted. By using electrochemical principle equations, the change of machining gap was simulated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.42-45
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• 2004

Electrochemical discharge machining (ECDM) has been found to be suitable for the micro-hole machining of nonconductive materials such as ceramics or glass compared with existing conventional and also non-conventional machining methods. However this machining process has some problems such as low geometric accuracy and low machining efficiency due to the random spark generation at the end of the electrode. This paper proposes the methods to improve the geometric accuracy of micro-hole using powder mixed ECDM process. The experimental results show the effects of powder producing improved geometric accuracy of machined hole and decreased concentration of spark energy.

• Journal of Environmental Science International
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• v.8 no.4
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• pp.539-545
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• 1999

Dye wastewater was treated by using an electrochemical oxidation process. Various combinations of electrodes such as carbon, Al and Fe were investigated. In this study, electrode material, electrolyte concentration, electrode distance, current density, and pH value were found to have significant effect on both pollutant removal efficiency and current efficiency in electrochemical oxidation process. After electrolysis for 40min with carbon/Al, it was observed that COD, $T-N, NH_{4}^{+}-N$ and color of treated wastwater were reduced from 580mg/$\ell$ to 145mg/$\ell$, 67.2mg/$\ell$ to 26.8mg/$\ell$, 46.8mg/$\ell$ to 1.4mg/$\ell$, and 4200 Pt-Co units to 336 Pt-Co units, respectively. The optimal conditions of the electrooxidation process to treat the wastewater for this study were found to be such : current density ; 16.67mA/$cm^2$, electrode distance ; 2.5cm, pH value ; 5.0 and carbon/Al electrode.

• Journal of environmental and Sanitary engineering
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• v.11 no.2
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• pp.53-58
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• 1996

This study was performed to measure and evaluate the characteristics of removal efficiency and kinetics in the electrolytic decolorizing process of dye wastewater containing acid dye Red 114 by using Fe anode. The synthetic wastewater samples of 500, 1000, $2000mg/{\ell}$ concentration were tested and as an attempt to assess the feasibility of the present system for the industrial application, a sample of wastewater collected by J textile factory in Eujungbu city was also treated. It was found that the optimum conditions were pH 7, 8Volt and removal efficiency in synthetic wastewater containing $2000mg/{\ell}$ of dye and 0.2% of electrolyte (NaCl) was 99.68% after 20minutes of reaction time. In this condition, overall rate constant was $4.77{\times}10^{-5}mmol/cm^{3}hr$. The Decolorizing efficiency and COD removal efficiency of J textile factory wastewater were 99% and 86% respectively at pH 7, 8Volt for 40minutes of reaction time.