• 대한화학회지
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• 제39권4호
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• pp.294-300
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• 1995

빛에 대한 폴리피롤(PPy)의 광전기화학적인 거동을 $Fe(CN)_6^{4-}/Fe(CN)_6^{3-}$과 $I^-/I_2$를 산화환원종으로 수용액에서 관찰하였다. PPy은 정전압법으로 Pt와 glassy-C 그리고 ITO에 각각 중합하였으며 PPy막을 입힌 전극에 빛이 쪼여졌을 때 산화환원종의 산화환원 전위에서 전류의 증가를 얻었다. 증가된 전류는 PPy이 갖는 반도체 특성과 빛에 의한 전극표면에서의 산화환원 광열촉진에 기인하며, PPy 중합시 사용한 지지전해질의 음이온(dopants)과 산화환원종, 용액의 pH에 의존하였다.

• Bulletin of the Korean Chemical Society
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• 제24권11호
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• pp.1609-1612
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• 2003

The electrooxidation of 8-(3-acetylimino-6-methyl 2,4-dioxopyran)-1-aminonaphthaline (AMDAN) in aqueous and non aqueous media led to the formation of polymeric films, poly (AMDAN). The monomer, undergo anodic oxidation through the formation of a monocation radical irrespective of the nature of the medium. In aqueous medium, the monocation radical undergoes, through its resonance structures, dimerisation involving tail-to-tail, head-to-tail and even head-to-head coupling. The products formed, being more easily oxidisable than the parent substance, undergo further oxidation at the same potential so that the overall oxidation involves a one-step (i.e., a single wave), two-electron process. In non-aqueous medium, the monocation radical does not undergo dimerisation through coupling reactions. Retaining its identity, monomer oxidise in two steps involving one electron in each step. The fact that the cathodic peaks corresponding to these anodic peaks are rarely observed indicates fast consumption of the electrogenerated monocation radicals and dications by follow-up chemical reactions to produce polymeric products (poly AMDAN). The electrochemical behavior of the formed polymer films was investigated in both non aqueous and aqueous media. The films prepared in non aqueous medium were found to be more electroactive than that the films prepared in aqueous medium. This is confirmed with the results in litreature which illustrate that the film prepared in aqueous solution hold water in its structure via hydrogen bonding, which causes decomposition reactions.

• 전기화학회지
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• 제7권1호
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• pp.9-15
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• 2004

Cyclic voltammetry and chronocoulometry have been used for characterization of catechol violet (CV) at the hanging mercury drop electrode in acetic acid-sodium acetate buffer solution. At pH 2.94 a nearly symmetric cyclic voltammetric wave due to an irreversible weak adsorption of CV on mercury was obtained at concentration of $0.53{\mu}mol\;dm ^{-3}$. Under these conditions, CV adsorbes in a monolayer. Upon increasing the concentration, the symmetry of the wave decreases; it can be attributed to a mixed diffusion adsorption process. The amount of the adsorbed catechol violet on the HMDE expressed as surface concentration as well as the surface areaf occupied by one molecule$(\sigma)$ were calculated. It was found that the values obtained for f and o utilizing cyclic voltammetric and chrono-coulometry are almost identical. A 1:1 and 1:2 Th (IV)-CV complexes are formed on addition of thorium (IV) to catechol violet. These complexes are adsorbed and reduced on the HMDE at more negative potentials than the peak potential of free CV, Using the square-wave (SW) technique, the adsorptive cathodic stripping voltammetry, ACSV, of these complexes was studied. It was found that the SW-ACSV of Th(IV)-CV can be applied to the determination of thorium at the nanomole level. Optimum conditions and the analytical method of determination were presented and discussed.

• 전기화학회지
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• 제16권3호
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• pp.145-150
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• 2013

In this study, the electrochemical investigation of various electrodes for reverse electrodialysis using potassium ferrocyanide and potassium ferricyanide as a redox system was carried out. Cyclic voltammetry was the employed method for this electrochemical study. From the results of cyclic voltammograms for various electrode materials, i.e., Au, Vulcan supported Pt, activated carbon, carbon nanofiber, Vulcan, the Vulcan electrode showed the lowest overpotential, but the Pt electrode having slightly higher overpotential obtained slightly higher anodic and cathodic current densities for the $Fe(CN)_6{^{4-}}/Fe(CN)_6{^{3-}}$ redox couple. The cyclic voltammograms for the Vulcan electrode confirmed very good electrochemical reversibility and kinetic behavior. As a result, among the electrode materials, the Vulcan electrode is the most promising electrode material for reverse electrodialysis.

• 한국세라믹학회지
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• 제53권5호
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• pp.489-493
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• 2016

Scandia ($Sc2O_3$)-stabilized zirconia (ScSZ) electrolyte-supported symmetrical solid oxide electrolyzer cells (SOECs), in which lanthanum strontium cobalt ferrite (LSCF)-gadolinia ($Gd_2O_3$)-doped ceria (GDC) composite materials are used as both the cathode and anode, were fabricated and their high temperature steam electrolysis (HTSE) performance was investigated. Current density-voltage curves were obtained for cells operated in 10% $H_2O$/90% Ar at 750, 800, and $850^{\circ}C$. It was possible to determine the ohmic, cathodic, and anodic contributions to the total overpotential using the three-electrode technique. The HTSE performance was significantly improved in the symmetrical cell with LSCF-GDC electrodes compared to the cell consisting of an Ni-YSZ cathode and LSCF-GDC anode. It was found that the overpotential due to the LSCF-GDC cathode largely decreased and, at a given current density, the total cell voltage decreased, which resulted in the enhanced hydrogen production rate in the symmetrical cell.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2001년도 추계학술발표회 초록집
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• pp.56-56
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• 2001

Ni-W alloy deposit is one of the best alternatives to hard chromium plating because of its good mechanical properties (high hardness, high strength, and good wear resistance). Ni-W alloy is deposited from weakly acidic or alkaline electrolytic bath with nickel sulfate, sodium tungstate or APT, and some kinds of organic hydroxy-acid complex and ammonia salts. W content of the deposit can be changed from 0 to 5Owt% and the coating with high W content is more attracted. But, meanwhile, the deposited layers are always found high internal stress, which cause them to become brittle and to bond insufficiently with the substrate. On the second hand, as the W content is incresed, the current efficiency reduced, which results in large quantities of hydrogen evolution and then produces bubbles on surface and pitting appearance In this paper, the influence of some additives on Ni-W alloy electroplating was investigated by means of compositional analysis and SEM. The initial results showed that 2-butyne-1,4-diol was the best brightener for Ni-W plating process. It could brighten and level deposit, but decreased the cathodic current efficiency. Its optimum concentration range is from O.lgjL to 0.5gjL. Besides, three kinds of additives including 2-butyne-1,4-diol were examined with Dagguchi method.

• 한국표면공학회지
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• 제19권3호
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• pp.92-108
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• 1986

An electroplating on the lead frame fabricated from domestic copper plate was studied experimentally. In this study, nickel was plated on the thin copper lead frame and silver layer was coated on the nickel film in the cyanide electrolyte. The effect of process variables such as current density, plating time, coating thickness and flow rate of electrolytic solution on the properties of coating was investigated. Some samples on each step were fabricated during electroplating. The results obtained from polarization measurement, observation of SEM photograph, adhesion test of coating and microhardness test are as follows. On silver plating, polarization resistance of potentiostatic cathodic polarization curve is reduced as the flow rate of Ag electrolytic solution increases. And above resistance is also reduced when the minor chemicals of sodium cyanide and sodium carbonate are added in potassium silver cyanide bath. The reduced polarization resistance makes silver deposition on the cathode easy. An increase in the current density and the coating thickness causes the particle size of deposit to coarsen, and consequently the Knoop microhardness of the coating decreases. On selective plating an increase in the flow rate of plating solution lead to do high speed plating with high current density. In this case, the surface morphology of deposit is of fine microstructure with high Knoop hardness. An increasing trend of the adhesion of coating was shown with increasing the current density and flow rate of electrolytic solution.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2011년도 춘계학술대회 및 Fine pattern PCB 표면 처리 기술 워크샵
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• pp.128-129
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• 2011

Mo 박막은 전기전도성과 열적 안전성이 우수하여 CIGS 용 후면전극으로 사용되고 있다. 많은 연구자들이 스퍼터링법을 이용하여 Mo 박막을 이중 박막으로 제조하고 있으며, CIGS 용 기판재로 SLG(Soda Lime Glass)와 연성기판재등이 주로 이용되고 있다. 연구에서는 SLG 기판재를 이용하여 스퍼터링법과 증착속도 및 이온화 등이 우수한 아크 이온 플레이팅법으로 Mo 박막을 제조하였으며, 제조된 Mo 박막을 CIGS 증착공정을 통하여 태양전지 효율을 측정하였다. 스퍼터링법과 아크 이온 플레이팅법으로 제조된 CIGS용 Mo 후면전극 위에 CIGS 박막 제조시 최대 효율은 11.43%, 11.14% 을 나타내었으며 Fill factor 는 67%와 57.3% 의 결과을 얻었다. 제조된 CIGS 셀의 단면 구조를 분석하기 위해 SEM 과 EDS 를 이용하였다. 두 공정방법으로 제조된 CIGS 셀의 단면을 관찰하여 Mo 전극위에 CIGS 박막 성장시의 입자크기가 스퍼터링법보다 아크 이온 플레이팅법이 박막성장이 더딘 것을 알 수 있었다. 그리고 아크 이온 플레이팅법을 이용한 SLG 기판재위에 CIGS 용 Mo 후면전극의 제조와 적용 가능성에 대해 알아보았다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2011년도 춘계학술대회 및 Fine pattern PCB 표면 처리 기술 워크샵
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• pp.47-48
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• 2011

The effect of solution acidity and organic additives, polyethylene glycol (PEG), on the trivalent chromium electroplating was systematically investigated in the view point of solution stability, electroreduction of trivalent chromium ions and characterization of deposition layer. It was found that, the concentration of fraction chromium complexes in the trivalent chromium bath containing formic acid is strongly depended on pH value. PEG molecules were stable in trivalent chromium bath containing formic acid via studies on electrospray ionization mass spectrometry (ESI-MS) and UV-Vis. However, the presence of PEG molecules decreased the reductive current of hydrogen evolution, increasing of current efficiency higher about 10 % compared with solutions without PEG. Moreover, PEG additives developed the nodular morphology during electroreduction of trivalent chromium ions with the increase of solution acidity and enhanced its current efficiency by maintaining the consumption of complexant, formic acid, at a low speed. In this study, the effect of solution acidity was emphasized important, there, it controlled the formation of complexes in the solution, cathodic film (CF) during deposition, and properties of deposited layer. By electrochemical quartz crystal microbalance (EQCM), studies show that chromium electrodeposition occurs via the formation of intermediate complexes and adsorption on the cathode surface, which hinder the penetration of ions from bulk solution to the cathode surface.

• 센서학회지
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• 제10권1호
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• pp.80-85
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• 2001

$Hg_{1-x}Cd_xTe$(MCT)박막을 $CdSO_4$, $TeO_2$, 및 $HgCl_2$이 혼합된 수용액을 사용하여 음극 전착법으로 ITO 유리와 티타늄기판 위에 성장하였다. 주된 박막의 성장 조건 변수로 전착전위와 성장 온도를 고려하였다. 전착된 MCT 박막은 SEM사진과 XRD 및 EPMA측정을 통하여 박막의 성장 조건이 결정 구조와 성분 조성비에 미치는 영향을 분석 연구하였다. XRD 분석으로부터 전착된 MCT 박막은 cubic zinc blonde 구조임을 알 수 있었고, EPMA에 의한 성분조성비의 분석결과로부터 전착전위를 변화시키므로서 MCT의 성분 조성비를 조절할 수 있음을 알 수 있었다.