• 한국수소및신에너지학회논문집
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• 제24권2호
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• pp.179-185
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• 2013

The behavior of surface film formation was greatly dependent on the speed of potential cycling. In $LiClO_4$ / EC + DEC, cyclic voltammetry results showed that the peaks originated from surface film formation on graphite electrode at the high charge-discharge rate was shifted to the lower potentials as the charge-discharge rate decrease. This indicates that surface films with different morphology and thickness were formed by different charge-discharge rate. Transmission electron microscopy (TEM) results indicated that the properties such as thickness and morphology of the surface film were greatly affected by the charge-discharge rate. Electrochemical impedance spectroscopy (EIS) showed that the resistance of surface film was affected by the speed of potential cycling. In addition, the charge transfer resistance was also dependent on the charge-discharge rate indicating that the charge transfer reaction was affected by the nature of surface film. TEM and EIS results suggested that the chemical property as well as the physical property of the surface film was affected by the charge-discharge rate.

• 한국표면공학회지
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• 제30권4호
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• pp.262-271
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• 1997

Nickel-matal hydride(Ni-MH) batteries are receiving attention as non-pollunting. high performance rehargeable energy stoage system. The performance of Ni-Mh is significantly influenced by the hydrogen storage alloy materiels used as an anode material. Recently, having discharge capacities higher than the $AB_5$-type hydrogen storage alloys, the Zr-based $AB_2$-Type hydrogen storage alloys has remaining problems regarding cycle life and self-dischareg. These problems need to be solved by improvements in the alloy design and/or surface treatment. This work investiggates the effects the effects of surface property by fluorination on $Zr_{0.7}Ti_{0.3}V_{0.4}Mn_{0.4}Ni{1.2}$ composittion $AB_2$-Type hydrogen storage alloys. EPMA, SEM and AES techniques were used for surface analysis, and the crystal structure was characterized by constant current cycling test and potential sweep methods. Fluorination was found to be effective when La-was incorporated into the alloy, and has unique morphology, higher reactivity, and at the same time formed a protective film. Through, fluorination, the cycle life of an electrode was found to increase significantly, charge/discharge characteristics of the electrode the potential difference between the charge/discharge plateau, i.e polarization(overpotential)were improved.

• 한국표면공학회지
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• 제52권2호
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• pp.53-57
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• 2019

Stability and activity of boron doped diamond (BDD) electrode are key factors for water treatment. In this study, BDD electrodes were prepared on various substrates such as Nb, Si, Ti, and $TiN_x/Ti$ by hot filament chemical vapor deposition (HFCVD) method. BDD/Ti film showed the delamination between BDD and Ti substrate due to the formation of TiC layer caused by diffusion of carbon. On the other hand, $BDD/TiN_x/Ti$ showed remarkably improved stability, compared to BDD/Ti. It was confirmed that $TiN_x$ intermediate layer act as barrier layer for diffusion of carbon. High potential window of 2.8 eV was maintained on the $BDD/TiN_x/Ti$ electrode and, better wastewater treatment capability and longer electrode working life than BDD/Nb, BDD/Si and BDD/Ti were obtained.

• 조명전기설비학회논문지
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• 제23권6호
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• pp.78-84
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• 2009

본 논문은 토양의 방전 영역에서 소규모 접지전극의 과도접지임피던스의 측정결과를 제시한다. 접지전극 주변에서 이온화 특성을 사실적으르 분석하기 위해서 세 가지 형상의 접지전극을 실외에 설치하고, 고전압 임펄스 발생기를 사용하여 시험전류를 인가하였다. 정지전극에서 대지로 흐르는 전류와 응답 전압을 분석한 결과, 접지전극 주변의 이온화는 높은 대지저항률률의 토양에서 접지임피던스 감소에 기여하며 대지전위상승을 효과적으로 제한하는 것이 확인된다. 하지만 낮은 대지저항률의 토양에서는 이온화 임계전계강도가 작아서 전극 형상이 과도접지임피던스에 거의 영향을 주지 못한다. 그리고 전극형상에 따른 실험결과, 판전극보다 침부봉전극이 이온화 영역 전압범위 내에서 과도접지임피던스 저감에 보다 효과적이다.

• 대한기계학회논문집B
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• 제27권6호
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• pp.714-725
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• 2003

The theory of the current-type electromagnetic flowmeter for a high temporal resolution was developed for two-phase flow measurements. To predict the output of the current-type flowmeter, the three-dimensional virtual potential distribution C and the newly introduced flow pattern coefficient f were derived and computed. The output of flowmeter depends on the liquid conductivity (sensitive to temperature) and flow configurations of the two-phase flow with the sinusoidal excitation over 100 Hz. The flow pattern coefficient was specially devised to separate the dependency on the flow configuration of the two-phase flow from that on the liquid conductivity which can be expressed with the calibration of single-phase flow. Using the finite difference method, the three-dimensional virtual potential distributions were computed for the electrode of finite size. By taking derivative of the virtual potential, the weight functions were evaluated and compared with existing analytic series solution for the point-electrode. There was a reasonable correspondence between the present and existing results. In addition, the flow pattern coefficients were evaluated for annular flows with various film thicknesses, and compared with the experimental results by the impedance spectroscopy. The numerical results agreed well with the experimental data.

• Journal of Electrochemical Science and Technology
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• 제7권2호
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• pp.115-131
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• 2016

Though battery chemistry and technology had been developed for over a hundred years back, increase in demand for storage energy, in the computer accessories, cell phones, automobile industries for future battery car and uninterrupted power supply, has made, the development of existing and new battery, as an emerging areas of research. With innovation of high energetic inexpensive Nano structure materials, a more energy efficient battery with lower cost can be competitive with the present primary and rechargeable batteries. Materials electrochemistry of electrode materials, their synthesis and testing have been explained in the present paper to find new high efficient battery materials. The paper discusses fundamental of electrochemistry in finding true cell potential, overvoltages, current, specific energy of various combinations of anode-cathode system. It also describes of finding the performance of new electrode materials by various experiments viz. i. Cyclic Voltammetry ii. Chronoamperometry iii. Potentiodynamic Polarization iv. Electrochemical Impedance Spectroscopy (EIS). Research works of different battery materials scientists are discussed for the development of existing battery materials and new nano materials for high energetic electrodes. Problems and prospects of a few promising future batteries are explained.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1776-1778
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• 1997

WIPS is a plasma device which has a wire anode, a coaxially-set cylindrical cathode, and aperture electrodes located in both ends of the cylinder. This electrode configuration forces the potential between the anode and the cathode to change logarithmically with radial direction. Since electrons are confined this logarithmic potential, the high-density plasma is produced even at a rather low anode voltage. In this paper we investigate characteristics of dc and pulse discharges, in which

• 대한화학회지
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• 제56권6호
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• pp.731-738
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• 2012

이 연구의 목적은 과학고등학교 학생들을 대상으로 설문지 조사와 면담을 통해 화학 전지에 대한 개념 이해를 분자적 수준의 미시적 관점에서 화학 평형과 연계하여 분석하는 것이다. 과학고등학교 학생들은 전극을 전해질에 담그자마자 전극의 금속이 산화되는 반응과 금속 이온이 환원되는 반응이 동시에 일어난다는 것과 화학 전지의 화학 평형 상태를 고르는 것에 대한 이해는 높았다. 그러나 전극과 전해질 사이에서 일어나는 상호작용을 미시적 관점으로 이해하는 데는 어려움을 겪고 있어, 화학 전지에서의 전위차 발생, 전자의 흐름, 반쪽 전지의 전위 측정, 산화전극과 환원전극 사이의 전지 전위값 계산하기 등에서는 어려움을 겪었다.

• 전기학회논문지
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• 제57권6호
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• pp.1102-1108
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• 2008

Wearable physiological signal monitoring systems are regarded as an important sensing unit platforms in ubiquitous/mobile healthcare application. In this paper, we suggested the modified bipolar electrodes implemented on the portable heart activity monitoring system, which minimized the distance of electrodes formed on a attachable pad. The proposed electrode configuration is useful in mobile measurement environments, but has a disadvantage of reduced amplitude of the heart action potential. In order to overcome the shortcoming of the suggested electrode configuration, we implemented the amplifying circuit to increase the signal-gain and decrease the artifacts. For evaluations, we analyzed the specificity of measured cardiography using the proposed electrodes through the comparing of heart activity monitoring system with standard clinical ECG(lead2) by pearson correlation coefficients. The result showed that the average correlation coefficient is $0.903{\pm}0.036,\;0.873{\pm}0.072$ at V3, V4 chest lead position, respectively. Thus, the modified bipolar electrode is quite suitable to monitor the electrical activity of the heart in the situation of the mobile environment, and could be considered having high similarity with standard clinical ECG.

• Elastomers and Composites
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• 제42권2호
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• pp.112-118
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• 2007

EPDM을 결합재로 사용하고, HRP를 고정시켜 과산화수소 정량을 위한 탄소반죽전극을 제작하고, 바이오센서로서 실용화 가능성을 살펴보기 위하여 전기화학적 특성을 고찰하였다. 실험 농도 영역에서 신호의 Lineweaver-Burk 도시가 보여준 좋은 직선성은 촉매력이 효과적으로 발휘될 수 있도록 EPDM이 전극 물질 속에서 HRP를 잘 고정하고 있음을 보여 주었으며, 이는 EPDM이 전극물질 결합재로 활용될 수 있음을 말하는 것이다. 전극은 낮은 전극전위($0.0\sim-1.0$ V vs. Ag/AgCl)에서 작동하였으며, 이 때 얻어진 신호는 높은 감도와 재현성을 보여 주었다. 특히 건조된 고무의 기계적 안정성은 탄소반죽 전극 실용화의 난제였던 실리콘 오일 결합재의 대체가능성을 열어주었다.