• Journal of the Korean Chemical Society
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• v.33 no.4
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• pp.399-405
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• 1989

The dependence of voltammetric parameters on the pressure for the reduction of Cu(II) in 0.5M KCl aqueous solution has been studied. In this system micro platinum electrode, standard calomel electrode and a helix type of platinum wire were used as the working, the reference and the auxilary electrode, respectively. With increasing the pressure from 1 to 1,800 bars, the half wave potentials of first reduction wave are shifted to the more negative potentials. And the diffusion currents of first and second reduction wave become considerably larger with increase in pressure from 1 to about 1,000 bars but are getting smaller beyond 1,000 bars. The good linear relationships between diffusion current and the concentrations of Cu(II) are established over all pressure range($1{\sim}1,800$ bars). The reversibility of the each reduction step is not changed with increasing pressure.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.407-411
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• 1999

Studies have been carried out on the fabrication of PPy/GC and PPy/Pt electrode modified with polypyrrole film and determination of Cr(VI) by using 3-electrode system with modified electrodes. Modified electrodes were able to easily fabricated by cyclic voltammetry scanned from +1.0V to -1.0V(vs. Ag/AgCl) at 50 mV/sec. Film thickness could be controlled at same condition by the number of cycling up to 26 times. Reduction behaviour of Cr(VI) at PPy/GC electrode could be seen at wide potential ranges from +0.6V to -0.5V(vs. Ag/AgCl), and maximum reduction peak potential of the ion was observed at -0.25V(vs.Ag/AgCl). Calibration graph at its potential was linear from 0.1 ppm to 80.O ppm. Slope factor and relative coefficient were 1.75 mA/ppm and 0.998, respectively. Reduction behaviour of Cr(VI) at PPy/Pt electrode was similar to PPy/GC electrode, Calibration graph was linear from l.0 ppm to 60.0 ppm. Slope factor and relative coefficient were 0.5mA/ppm and 0.923, respectively. But PPy/GC modified electrode had about 3 times higher sensitivity than PPy/Pt modified electrode. Reduction behaviour of Cu(II), As(IlI), Pb(II), and Cd(II) couldn't be seen at PPy/GC electrode,Its metals had not lnterfered with Cr (VI) determination.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.54-54
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• 1992

ITO투명전극/WO$_3$박막/LiClO$_4$-PC/백금 대향전극 구조를 갖는 일렉트로 크로믹 소자를 구성하여 WO$_3$박막의 일렉트로크로믹 특성을 조사하였다. WO$_3$박막의 coloration의 LiClO$_4$-PC 유기전해질과 ITO 투명전극으로부터 Li$^{+}$이온과 전자들의 이중주입에 의하여 청색으로 나타났으며, 전기화학전인 산화반응에 의하여 bleaching 현상이 가역적으로 일어났다. Coloration 과 bleaching 현상, 광학밀도, 구동전압 및 응담속도등의 일렉트로크로믹 특성은 WO$_3$ 박막의 성장 조건, WO$_3$박막 두께, ITO 투명전극의 sheet resistance, 대향전극 및 인가전압에 크게 의존하는 것으로 밝혀졌다.

• Journal of the Korean Electrochemical Society
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• v.2 no.4
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• pp.227-231
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• 1999

Disposable, amperometric glucose sensor was constructed using platinised carbon paste electrode. The sensor response was studied by amperometry and cyclic voltammetry applying sample solutions on the strip-type electrode. Platinization of screen-printed carbon paste electrode effectively improved the electrochemical reversibility of a mediator and the analytical characteristics of the sensor. The heterogeneous rate constant for $[Fe(CN)_6]^{4-/3-}$ was $1.45\times10^{-2}cm{\cdot}s^{-1}$. An applied potential of 0.3V vs. Ag/AgCl resulted in the best selectivity for glucose. The apparent Michaelis-Menten constant for glucose on the strip sensor, $K_m^{app}$, was 24.5 mM. To evaluate the analytical performance of the glucose sensor strip, a correlation study was performed with the NOVA S.P, Ultra M analyzer for 30 serum samples containing $80\~297mg/dL$ of glucose: the correlation coefficient value was 0.983. It can be seen that the strip sensor has satisfactory precision and accuracy.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.5
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• pp.242-248
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• 2016

The overall reaction rate of fuel cell is governed by oxygen reduction reaction (ORR) in the cathode due to its slowest reaction compared to the oxidation of hydrogen in the anode. The ORR efficiency can be readily evaluated by examining the adsorption strength of atomic oxygen on the surface of catalysts (i.e., known as a descriptor) and the adsorption energy can be controlled by transforming the surface geometry of catalysts. In the current study, the effect of the surface geometry of catalysts (i.e., strain effect) on the adsorption strength of atomic oxygen on platinum catalysts was analyzed by using density functional theory (DFT). The optimized lattice constant of Pt ($3.977{\AA}$) was increased and decreased by 1% to apply tensile and compressive strain to the Pt surface. Then the oxygen adsorption strengths on the modified Pt surfaces were compared and the electron charge density of the O-adsorbed Pt surfaces was analyzed. As the interatomic distance increased, the oxygen adsorption strength became stronger and the d-band center of the Pt surface atoms was shifted toward the Fermi level, implying that anti-bonding orbitals were shifted to the conduction band from the valence band (i.e., the anti-bonding between O and Pt was less likely formed). Consequently, enhanced ORR efficiency may be expected if the surface Pt-Pt distance can be reduced by approximately 2~4% compared to the pure Pt owing to the moderately controlled oxygen binding strength for improved ORR.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.224-231
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• 1990

To improve the dispersion of platinum catalyst, the effects of carbon black surface treatment, solvents, surfactants, and ultrasonic homogenizing were examined. Upon introducing the hydrophilic groups acting as an anchorage center of the catalyst on the surface of carbon black by oxidation, the migrating and growing of platinum particles(or ions) during reduction could be restricted. When mixed solvents, surfactants, or ultrasonic homogenizer were used to disperse catalysts on the carbon black, the dispersion of catalyst could be improved, due to the good permeation of chloroplatinic acid through the pore of carbon black. Among the impregnation methods, the method using ultrasonic homogenizer with mixed solvent was the most excellent. Using this method the particle sized could be minimized in less than $30A^{\circ}$ and distributed homogeneously.

• Korean Journal of Materials Research
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• v.10 no.5
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• pp.360-363
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• 2000

Deformation in the hysteresis loop of $Pb(Zr,Ti)O_3$ (PZT) thin films with various Zr/Ti ratios has been studied by varying the top electrode preparation method and the annealing temperature. Pt/PZT/Pt capacitors was found to be positively poled due to dc plasma potential generated during reactive ion etch (RIE) of Rt. Internal field is formed by space charges trapped at domain boundaries. Aging phenomenon such as constriction in the middle of the hysteresis loop was observed in the PZT film with top electrode deposited by sputtering. Top electrode annealing restores the hysteresis loop by removing the space charges. As Zr/Ti ratio decrease, voltage shift increases and an-nealing temperature at which internal field disappears also increases.

• Resources Recycling
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• v.20 no.4
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• pp.52-57
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• 2011

Present paper reports a new method to separate the electrolyte membranes and carbon paper without using ultrasonic waves and stirring. In this method, these were separated from fuel cell membrane-electrode assembly(MEA) using the distilled water, butanol and surfactant by dipping method without the dispersion of catalyst particles. Separated carbon paper catalysts and fuel cell Pt/C catalysts were heated in aqua regia at $80{\sim}85^{\circ}C$ and added to precipitant. After calcination, Pt metal was recovered which might be used in fabricating new fuel cells.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.157-157
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• 2015

전기화학 성능이 우수하고 고내구성 고속 구리 전해도금용 DSE를 개발하기 위해 전기화학적 특성이 좋은 백금족 산화물의 조성비, 전처리 등의 공정으로 전극을 제조한 후, 고 전류밀도 조건에서 구리 전해도금을 실시하여 유기첨가제 소모율을 측정하여 최적의 전극제조 공정 조건을 확보하였다. 최적조건의 전극과 시제품 전극들을 비교분석한 결과, 상용 DSE와 비슷하거나 상회하는 내구수명을 가지는 것을 확인하였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.278-279
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• 2007

본 논문에서는 메조포러스 백금 전극이 적용된 무효소 혈당센서를 실리콘 기판 위에 제작하여 향후 CMOS 회로와의 집적이 가능하도록 설계하였으며, 초소형 무효소 혈당센서 구조의 최적화를 위하여 동일한 면적에서 여러 가지 구조의 센서를 설계 및 제작을 하고 그 결과를 비교 분석하였다. 제작된 무효소 혈당센서는 3전극시스템으로 구성되고 그 특성은 작동전극과 타 전극사이의 간격에 가장 민감한 변화를 보였다. 최적화된 구조를 갖는 센서는 11.1mM glucose실험에서 12.9${\mu}A$의 응답전류를 얻었으며 이 값은 효소를 사용한 센서와 비교하여도 월등히 큰 응답임을 알 수 있었다. 또한 제작된 센서들은 구조 최적화를 위하여 $9mm^2$로 동일한 크기로 실험을 하였지만, 이 크기는 응답전류가 매우 크므로 더욱더 소형화가 가능함을 알 수 있다.