• 한국전기전자재료학회논문지
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• 제17권12호
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• pp.1337-1340
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• 2004

The self-assembled monolayers of alkane derivatives with sulfur containing head groups on gold substrates have been widely examined recently, since the binding between S atoms and Au surface is strong. The viologen has been widely investigated their well-behaved electrochemistry including electron transfer mediation, the surface-enhanced of the adsorption and the behavior of supramolecular assemblies at electrode surfaces in theses and various studies. Yiologen monolayers are formed onto QCM by self-assembly method. We studied the relationship of electron transfer from changing the anions in 0.1 M NaCl and NaClO$_4$ electrolyte solution. The EQCM measurements revealed the anions transfer during reduction and oxidation, respectively From the EQCM data, the well-defined shape peaks were nearly equal charges by cyclic voltammetry.

• 대한기계학회논문집
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• 제9권1호
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• pp.1-9
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• 1985

본 연구에서는 이러한 점에도 역점을 두어서 초기 피로균열의 발생.거동을 관 찰하기 쉬운 연강을 선택하여 편진인장반복하중을 작용시켜, 연강 평골재의 표면상에 발생.성장하는 미소표면균열의 거동을 전자현미경과 광학현미경을 병용하여 표면과 파 단면을 입체적으로 조사하여, 피로균열의 초기발생상태를 조사하고, 그 성장율을 조사 하여 파괴역학적으로 해석하여 그 특성을 조사한다.

• 전자공학회논문지A
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• 제29A권4호
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• pp.22-27
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• 1992

The cyclic voltammogram characteristics at the magnetized SrO${\cdot}6Fe_{2}O_{3}$ ceramics/(($10^{-3}$M KCI + p-Si powders) and /(($10^{-4}$M CsNO$_3$ + n-GaAs powders) suspension interfaces have been studied using the microelectrophoresis and the cyclic voltammetric method. The negatively charged ions are specifically absorbed on the virgin and the magnetized SrO${\cdot}6Fe_{2}O_{3}$ ceramics surfaces. The zeta potentials of the p-Si and n-GaAs colloidal semiconductors are + 41mV and -44.8mV, respectively. The magnetization effects act as potential barriers at the magnetized SrO${\cdot}6Fe_{2}O_{3}$ interfaces. The positivelely charged p-Si and the negatively charged n-GaAs colloidal semiconductors act as potential barriers at the virgin SrO${\cdot}6Fe_{2}O_{3}$ interfaces. On the other hand, the charged p-Si and n-GaAs colloidal semiconductors act as potential barrier scavengers at the magnetized SrO${\cdot}6Fe_{2}O_{3}$ interfaces. The magnetization effects and the charged colloidal semiconductor effects are irreversible and interdependent.

• 한국전기전자재료학회논문지
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• 제19권3호
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• pp.246-249
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• 2006

We fabricated self-assembled monolayers(SAMs) onto quartz crystal microbalance(QCM) using viologen, which has been widely used as electron acceptor and electron transfer mediator. We determined the time dependence on resonant frequency shift during self-assembly process and observed the morphology of self-assembled monolayers by STM and investigated the electrochemical behavior of SAMs by cyclic voltammetry. Electrochemical deposition of viologen was investigated using electrochemical quartz crystal microbalance(EQCM). The redox reactions of viologen were highly reversible and the EQCM has been employed to monitor the electrochemically induced adsorption of SAMs during the redok reactions. The total frequency change was about 9.5 Hz, and 7.1 Hz. From the data, we could know the mass change was about 10.16 ng and 7.60 ng, respectively. Finally, the EQCM has been employed to monitor the electrochemically induced adsorption of self-assembled monolayers on Au surfaces.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.338-339
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• 2005

The wider surface of the aluminum foil, electrochemically very important and it is necessary to increase the surface area. A study has been made of the fabrication condition for etching cube texture of high purity aluminium foil and of electrochemical etching of the aluminium foil. In the present work, it is shown there exists a relation between the influence of the pre-treatment time in the NaOH & HCI solution and $H_2SO_4$ concentration in the conversion solution. Also effect of temperature during AC etching was also studied. Result of the etched aluminum film is shown in the typical SEM images. Its electrochemical characteristics were investigated by cyclic voltammetry. And effects of current density and frequency is also reported. Cyclic voltammogram showed that the protective oxide film was formedon the inner surfaces of etch pit. the frequency influence resistance of oxide film in AC etching.

• Structural Engineering and Mechanics
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• 제39권4호
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• pp.499-520
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• 2011

The effectiveness of a technique for the repair of reinforced concrete members in combination with a technique for the repair of masonry walls of infilled frames, damaged due to cyclic loading, is experimentally investigated. Three single - story, one - bay, 1/3 - scale frame specimens are tested under cyclic horizontal loading, up to a drift level of 4%. One bare frame and two infilled frames with weak and strong infills, respectively, have been tasted. Specimens have spirals as shear reinforcement. The applied repair technique is mainly based on the use of thin epoxy resin infused under pressure into the crack system of the damaged RC joint bodies, the use of a polymer modified cement mortar with or without a fiberglass reinforcing mesh for the damaged infill masonry walls and the use of CFRP plates to the surfaces of the damaged structural RC members, as external reinforcement. Specimens after repair, were retested in the same way. Conclusions concerning the effectiveness of the applied repair technique, based on maximum cycles load, loading stiffness, and hysteretic energy absorption capabilities of the tested specimens, are drawn and commented upon.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.601-604
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• 2014

Two classes of morpholino-substitued thioacetate have been successfully synthesized and their electrochemical properties of self-assembled monolayers (SAMs) on Au electrode are measured by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The barrier property of the SAMs-modified surfaces is evaluated by using potassium ferro/ferri cyanide. The results suggest that the arenethioacetate forms higher-quality close-packed blocking monolayers in comparison with alkanethioacetate. Furthermore, it has shown that the barrier properties of these monolayers can be significantly improved by mixed SAMs formation with decanethiol. From our experimental results we find that the electron transfer reaction of $[Fe(CN)_6]^{3/4-}$ redox couple occurs predominantly through the pinholes and defects present in the SAM and both SAMs show a good and fast capacity in recognition for $Ag^+$. The morphological and elementary composition have also been examined by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).

• 한국표면공학회지
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• 제28권1호
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• pp.34-45
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• 1995

An amphiphilic nitroxide radical(2,2'6,6'-tetramethyl-4-octadecyioxy-1-piperidinyloxyl, TEMOPO) or mixture of TEMOPO and arachidic acid(Icosanoic acid, AA), was spread on water surface by the Langmuir-Blodgett(LB) method and surface pressure-area curve was measured. Such monolayer films of TEMOPO were transferred onto surfaces of photo transferable tin oxide electrodes(PTTO) by the LB method under various surface pressure with the transfer ratio of larger than 0.95 at the surface pressure higher than 15mN/m. The electrochemical effect of functional nitroxy radical monolayer onto semi-conductive electrode to electrolyte have been investigated by using LB method. Cyclic voltammetry technique was used for the electrochemical behavior measurement of TEMOPO monolayer onto the PTTO in 0.18 mo1/$dm^3$ $H_2SO_4$ solutions. The shape of voltammograms was found to change from one electrode to another. The amount of charge for the oxidation and the re-reduction of the cation to TEMOPO were evaluated from graphical integration. The amounts of charge were always smaller than those predicted from the $\pi$-$\sigma$ curves though the transfer ratio was unity. The poor reproducibility of the cyclic voltammograms was improved by the mixing with AA. Structure and arrangement of monomolecular layer on water surface and electrode were studied. Characteristics of monolayer film applied for the mediation reaction was also discussed by electrochemical method.

• 한국세라믹학회지
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• 제50권6호
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• pp.539-544
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• 2013

A simple synthetic process is demonstrated for the preparation of MnS/carbon nanotube (CNT) composites for Li ion battery electrodes. CNTs were initially treated using a strong acid solution to generate carboxylate ions ($-COO^-$) on their surfaces. The MnS/CNT composites were synthesized by a polyvinyl-pyrrolidone-assisted hydrothermal method in the presence of as-functionalized CNTs. The phase and morphology of the MnS/CNT composites and pure MnS microspheres were characterized using X-ray diffraction and high-resolution transmission electron microscopy. Furthermore, the Li electroactivity levels of the MnS/CNT composites and MnS microspheres were investigated using cyclic voltammetry and galvanostatic cycling. The MnS/CNT composite electrodes showed higher specific capacities exceeding 365 $mA\;h\;g^{-1}$ at a C/10 current rate and enhanced cyclic performance compared to pure MnS microspheres.

• 한국표면공학회지
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• 제30권2호
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• pp.93-103
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• 1997

High temperature materials used in the elevated temperature and corrosive atmosphere must have the good oxidation resistance and preserve their own mechanical properties simultaneously. For the oxidation resistance, it is very important to form a protective oxide scale such as $Al_2O_3$ or $Cr_2O_3$ on the substrate. However, the additions of protective oxide forming elements such as Cr and Al in the alloy to enhance its oxidation resistance are limited due to the deleterious effects on their mechanical properties. PECVD(P1asma Enhanced Chemical Vapor Deposition) coating processes were employed to improve the oxidation resistance at high temperature. Cr and/or A1 were coated on the substrates of Ni and Inconel 600 at various temperatures of 400, 500, $600^{\circ}C$ and at different conditions of specimen surfaces. Then, coated specimens were exposed to isothermal and cyclic oxidation conditions in air at 1000 and $1100^{\circ}C$. In order to enhance the adhesion between the substrate and coated layer, heat treatments of the coated specimens were conducted in a vacuum. At isothermal oxidation experiments, Al-coated Ni specimen showed better oxidation resistance than pure Ni. At cyclic oxidation experiments at $1000^{\circ}C$. Cr and Al-coated specimen showed better oxidation resistance. Cr-coated Inconel 600 had also showed better oxidation resistance due to Cr in the substrate. By PECVD coating process, oxidation resistance could be improved, but it was not improved as expected due to the weakness of the adhesion between the substrate and the coated layer.