• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.311-316
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• 2012

We are investigated to an electrochemical characteristic for Langmuir-Blodgett (LB) films by cyclic voltammetry method. The phospholipid compound was deposited by using the LB method on the Indium tin oxide(ITO) glass. We tried to measure the electrochemical by using cyclic voltammetry with three-electrode system(an Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode) in 0.5, 1.0, 1.5 and 2.0 N $NaClO_4$ solution. A measuring range was reduced from initial potential -1350 mV, continuously oxidized to 1650 mV. As a result, LB films of the phospholipid compounds are appeared irreversible process caused by only the oxidation current from the cyclic voltammogram. The diffusivity(D) effect of LB films decreased with increasing of phospholipid compound amount.

• Journal of the Korean Applied Science and Technology
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• v.22 no.4
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• pp.315-322
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• 2005

We investigated the electrochemical properties for Langmuir-Blodgett (LB) films mixed with 4-octyl-4'-(5-carboxylpentamethyleneoxy)azobenzene (denoted as 8A5H) and $phospholipid(L-{\alpha}-dimyristoylphosphatidylcholine$, denoted as DMPC). LB films of 8A5H monolayer and 8A5H-DMPC were deposited by using the Langmuir-Blodgett method on the indium tin oxide(ITO) glass. The electrochemical properties measured by using cyclic voltammetry with a three_electrode system, an Ag/AgCl reference electrode, a platinum wire counter electrode and LB film-coated ITO working electrode at various concentrations(0.1, 0.5, and 1.0mol/L) of $NaClO_4$ solution. A measuring range was reduced from initial potential to -1350mV, continuously oxidized to 1650mV and measured to the initial point. The scan rates were 50, 100, 150 and 200mV/s, respectively. As a result, LB films of 8A5H monolayer appeared irreversible process caused by only the oxidation current from the cyclic voltammogram and LB films of 8A5H-DMPC mixture were found to be caused by a reversible oxidation-reduction process.

• Journal of the Korean Applied Science and Technology
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• v.20 no.2
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• pp.94-100
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• 2003

We studied electrochemical characteristics of Langmuir-Blodgett(LB) films by using cyclic voltammetry with a three-electrode system. An Ag/AgCl as a reference electrode, a platinum wire as a counter electrode and LB film-coated indium tin oxide(ITO) as a working electrode were used to study electrochemical characteristics at a various concentration of $NaClO_4$ solution. LB films were reduced from initial potential to -1350 mV, continuously oxidized to l650mV and returned to the initial point. The scan rate was l00mV/s. The monolayer surface morphology of the LB film have been measured by Atomic Force Microscope(AFM). As a result, We comfirmed that the microscopic properties of LB film by AFM showed the good orientation of momolayer molecules and the thickness of monolayer was 3.5-4.lnm. The cyclic voltammograms(CV) of the ITO-coated glass showed the peak potentials for the reduction-oxidation reation. LB films of 4-octyl-4'-(5-carboxypentamethyleneoxy) azobenzene(8A5H) / L-${\alpha}$-phosphayidyl choline, dilauroyl(DLPC) seemed to be irreversible process caused by only the oxidation current from the cyclic voltammogram. The current of oxidatation increased at cyclic voltammogram by increasing 8A5H density in LB films. The diffusivity(D) of LB films increased with increasing of a 8A5H amount and was inversely proportional to the concentration of $NaClO_4$ solution.

• Journal of the Korean Applied Science and Technology
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• v.31 no.1
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• pp.66-73
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• 2014

In this work, the current-voltage curves for stainless steel in the ethanolamine solution containing alkyl group were measured using the conventional three electrodes of cyclic voltammetry. Stainless steel as working electrode, Ag/AgCl electrode as reference electrode and Pt wire as counter electrode were used respectively. As a result, the C-V characteristics of stainless steel were to be for an irreversible process due to the oxidation current from cyclic voltammogram, using N-ethylethanolamine and N,N-dimethylethanolamine solutions. Effective diffusivity of corrosion inhibitors was decreased with increasing concentration. It was found from SEM images of the metal that the electrolyte (specific name ?)(0.5 N) as corrosion inhibitor was added into a N, N-diethylethanolamine solution ($1.0{\times}10^{-3}M$) containing copper and nickel, the corrosion inhibiting effect was enhanced.

• Journal of Microbiology and Biotechnology
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• v.22 no.10
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• pp.1446-1451
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• 2012

Levodopa or L-3,4-dihydroxyphenylalanine (L-DOPA) is the precursor of the neurotransmitter dopamine. L-DOPA is a famous treatment for Parkinson's disease symptoms. In this study, electroenzymatic synthesis of L-DOPA was performed in a three-electrode cell, comprising a Ag/AgCl reference electrode, a platinum wire auxiliary electrode, and a glassy carbon working electrode. L-DOPA had an oxidation peak at 376 mV and a reduction peak at -550 mV. The optimum conditions of pH, temperature, and amount of free tyrosinase enzyme were pH 7, $30^{\circ}C$, and 250 IU, respectively. The kinetic constant of the free tyrosinase enzyme was found for both cresolase and catacholase activity to be 0.25 and 0.4 mM, respectively. A cyclic voltammogram was used to investigate the electron transfer rate constant. The mean heterogeneous electron transfer rate ($k_e$) was $5.8{\times}10^{-4}$ cm/s. The results suggest that the electroenzymatic method could be an alternative way to produce L-DOPA without the use of a reducing agent such as ascorbic acid.

• Journal of Welding and Joining
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• v.14 no.1
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• pp.57-67
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• 1996

With an expansion in automation of welding processes, emphasis has been shifted from other welding processes to the GMA welding. However, there is a problem with this process that the spatter occurs very frequently. In GMA welding, there are several types in the way of metal transfer from the electrode wire to the weld pool, which have a close relatonship with the spatter genetration. This study was concerned with the spatter occurring in the short-circuiting transfer. In welding with short-circuiting, the electromagnetic force formed by the welding current facilitatics the rupture of the metal bridge between the wire and workpiece and ensures the normal process of the welding process. However, the spatter can be genetrated from the droplet because of the upward magnetic force, when the droplet contacts with the weld pool. The passage of current through the bridge results in the accumulation of the thermal energy, which causes the bridge to explode in the final stage of short-circuiting, thus forming the spatter. Based on the above phenomena in conjunction with other experimental results published, the physical phenomenon related with the occurrence of spatter was modeled and the current waveform was investigated to reduce the spatter. Finally, the fuzzy rule based method was proposed to predict the time of short-circuiting and arcing in the metal transfer.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.12
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• pp.1563-1575
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• 1997

To understand EHD nucleate boiling heat transfer enhancement, EHD effects on R-113 nucleate boiling heat transfer in a non-uniform electric field were investigated. The pool boiling heat transfer and the dynamic behavior of bubbles in d.c./a.c. electric fields under a saturated or subcooled boiling were studied by using a plate-wire electrode and a high speed camera. From the pool boiling heat transfer study, the shift of the pool boiling curve, the increase of the heat transfer and the delay of ONB and CHF points to higher heat fluxes were observed. From the dynamic behavior of bubbles, it was observed that bubbles departed away from the whole surface of the heated wire in radial direction due to EHD effects by a nonuniform electric field. With increasing applied voltages, the bubble size decreased and the active nucleation site and the departure number of bubbles showed the different trend. The present study indicates that the EHD nucleate boiling heat transfer is closely connection with the dynamic behavior of bubbles and the secondary flow induced near the heated surface. Therefore, the basic studies on the bubble behavior such as bubble frequency, bubble diameter, bubble velocity and flow characteristics are necessary for complete understanding of the enhancement mechanism of the boiling heat transfer using an electric field.

• Journal of the Korean Chemical Society
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• v.41 no.7
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• pp.337-342
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• 1997

Acryloylmethylbenzo-15-crown-5 was prepared from the reaction of 4'-hydroxymethylbenzo-15-crown-5 with acryloyl chloride. And, poly(acryloylmethylbenzo-15-crown-5) [poly(AMB15C5)] was synthesized by radical polymerization using AIBN as initiator in benzene. Coated wire lead(II) ion-selective electrodes ($Pb^{2+}$-CWISEs) using either poly(AMB15C5) or B15C5 as neutral carrier were prepared, respectively. $Pb^{2+}$-CWISEs gave linear responses with slopes of 28$\pm$ 1mV per decade within the concentration range of $10^{-5} M{\sim}10^{-1}$ M, respectively. Also, the detection limits were $10^{-6}$ M and response times were either 3 or 5 min. for B15C5 and poly(AMB15C5), respectively. $Pb^{2+}$-CWISE base on B15C5 was rather unstable than poly(AMB15C5)'s due to solubility of the B15C5 in water. The selectivity coefficients of a variety of interfering ions such as $Mg^{2+},\; Ca^{2+},\; Co^{2+},\; Ni^{2+},\; Cu^{2+},\; Zn^{2+}$ and $Cd^{2+}$ were small ($10^{-4}{\sim}10^{-5}$), while those of $Na^+$ and $K^+$ were large (0.1∼0.01). In addition, the electrode responses depended upon the pH of test solution and the composition of the membrane. In the range pH 3∼6 of test solution, potentials of Pb2+-CWISEs were hardly changed. The optimal contents of B15C5 and poly(AMB15C5) were 7.7 wt% and 13.1 wt%, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.1
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• pp.77-84
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• 2003

HS, Ammonia, CH$_4$, VOCs, Microorganism, Bacteria etc produced from swineries or henhouses are known to prevent the growth of livestock. Moreover, they give an unpleasant feeling to the workers. In this study, a methodology to remove odors and toxic gases by oxidation of ozone was thus accomplished. However, most ozone generators which use the atmospheric surrounding air have problems of contamination of electrode for discharge. Therefore in this work, a wire-cylinder type plasma reactor with DC voltage has been used both in a laboratory scale test and in the real swinery to solve the existing problems. About 6 cm of electrode gap could decrease the attachment of dusts, humid aerosols and other polymers, which are contained in the air. This compact designed device could produce ozone to oxidize and remove the air pollutants. But the amount of ozone was not large enough to be harmful to human Health. Also, the concentration of ozone was able to be varied by the input voltage. which makes it available for the proposed system to be installed in various kinds of pig houses. With this device, at maximum 43 mg/㎥ (20 ppm) of ozone could be produced at 40 ㎸ input voltage (consumed energy was 0.1 Wh/㎥). A program was also made in this work to calculate the optimum parameters for design of a plasma reactor in wide range of conditions.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1687-1689
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• 1998

In this work, the behaviours of conducting wire type particles within the coaxial electrode gap energized with high ac voltage have been systematically investigated using charge simulation method. For this, spheroidal charge is adopted as a image charge for the CSM analysis in order to calculate the acquired charge of the particles which are erected on the surface of the outer electrode. For this purpose, the effects of the lengths and diameters of Cu, Al particles in gas insulated system have been studied by a numerical computation and particle lifting voltage, lifting field, breakdown voltage, acquired charge and travelling distance have been considered. From this, we understand that the particle behaviours have different characteristics according to the particle lengths and diameters. And a possible countermeasure, based on the proposed simulation, has been provided with a view to estimating the flashover voltage of $SF_6$ gas under the 1 atm.