• Korean Chemical Engineering Research
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• 제54권3호
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• pp.305-309
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• 2016

최근에 저가의 고분자 전해질 연료전지(Proton Exchange Membrane Fuel Cells, PEMFC)용 비불소계 전해질 막 연구개발이 활발히 진행되고 있다. 본 연구에서는 sulfonated Poly (ether ether ketone) (sPEEK) MEA 내구성을 시험하기 위해 열화 가속화 기법을 이용하여 막과 전극이 동시에 열화되는 MEA 열화 실험을 진행하였다. 열화 전과 후에 I-V 분극곡선, 수소투과도, 전극 활성 면적, 막 저항과 부하 전달 저항을 측정하여 열화 전과 후를 비교하였다. sPEEK 막의 수소 투과도는 낮았지만, 저가습 OCV 조건에서 발생하는 라디칼에 Nafion과 같은 불소계막보다 sPEEK 막이 약했다. MEA 열화 실험 결과 144시간 후와 271시간 후 성능이 각각 15%와 65% 감소하였다. 144이후 급격한 성능감소의 주요인은 막에 발생한 핀홀의 Pt/C 입자에 의한 shorting 현상이라고 본다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.163.2-163.2
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• 2010

In this work, nano-flake shaped nickel oxide (NiO) films were synthesized by chemical bath deposition technique for electrochemical capacitors. The deposition was carried out for 1 and 2 h at room temperature using nickel foam as the substrate and the current collector. The structure and morphology of prepared NiO film were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). And, electrochemical properties were characterized by cyclic voltammetry, galvanostatic charge-discharge, and AC impedence measurement. It was found that the NiO film was constructed by many interconnected NiO nano-flakes which arranged vertically to the substrate, forming a net-like structure with large pores. The open macropores may facilitate the electrolyte penetration and ion migration, resulted in the utilization of nickel oxide due to the increased surface area for electrochemical reactions. Furthermore, it was found that the deposition onto nickel foam as substrate and curent collector led to decrease of the ion transfer resistance so that its specific capacitance of a NiO film had high value than NiO nano flake powder.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.749-752
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• 2009

Anodized tubular titania ($TiO_2$) electrodes (ATTEs) are prepared and used as both the photoanode and the cathode substrate in a photoelectrochemical system designed to split water into hydrogen with the assistance of an enzyme and an external bias (solar cell). In particular, the ATTE used as the cathode substrate for the immobilization of the enzyme is prepared by two methods; adsorption and crosslinking. Results show that the optimized amount of enzyme is 10.98 units for the slurried enzyme, 3.66 units for the adsorbed one and 7.32 units for the crosslinked one, and the corresponding hydrogen evolution rates are 33.04, 148.58, and 234.88 umol/hr, respectively. The immobilized enzyme, specifically the chemically crosslinked one, seems to be much superior to the slurried enzyme, due to the enhanced charge-transfer process that is caused by the lower electrical resistance between the enzyme and the ATTE. This results in a greater number of accepted electrons and a larger amount of enzymes able to deal with the electrons.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.73-76
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• 1998

We give pressure stimulation into organic thin films and detect the induced displacement current. then manufacture a device under the accumulation condition that the state surface pressure is 15[mN/m]. In processing of a device manufacture. We can see the process is good from the change of a surface pressure for organic thin films and transfer ratio of area per molecule. The structure of manufactured device is Au/organic thin films(polyimide)/Au, the number of accumulated layers are 31,35, and 41. I-V characteristic of the device is measured from 0[V] to +5[V]. The maximum value of measured current is increased as the number of accumulated layers are decreased. The resistance for the number of accumulated layers, the energy density for an input voltage show desired results, and the insulation of a thin film is better as the interval between electrodes is larger.

• Journal of Electrochemical Science and Technology
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• 제7권2호
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• pp.153-160
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• 2016

The inhibition ability of N,N-bis(2,4-dihydroxyhydroxybenzaldehyde)-1,3-Propandiimine (DHBP) as a schiff base against the corrosion of API-5L-X65 steel in 1 M HCl solution was evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization and scanning electron microscopy. Electrochemical impedance studies indicated that DHBP inhibited corrosion by blocking the active corrosion sites. The inhibition efficiency increased with increasing inhibitor concentrations. EIS data was analysed to equivalent circuit model and showed that the charge transfer resistance of steel increased with increasing inhibitor concentration whilst the double layer capacitance decreased. The adsorption of this compound obeyed the Langmuir adsorption isotherm. Gibbs free energy of adsorption was calculated and indicated that adsorption occurred through physical and spontaneous process. The corrosion inhibition mechanism was studied by potential of zero charge. Polarization studies indicated that DHBP retards both the cathodic and anodic reactions through adsorption on steel surface. Scanning electron microscopy was used to study the steel surface with and without inhibitor.

• 한국철도학회논문집
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• 제14권5호
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• pp.411-415
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• 2011

DC/DC컨버터는 임의의 직류전원을 부하가 요구하는 형태의 직류전원으로 변환시키는 전력변환기이다. 전압모드 DC/DC 컨버터는 주기적으로 입력측에서 출력측으로 전달되는 에너지를 제어하는 기능을 수행하기 위해 MOSFET(산화물-반도체 전계 효과 트랜지스터), 인덕터, PWM 제어기(오실레이터, 연산증폭기, 비교기로 구성)를 이용한다. 본 논문에서 PWM(펄스폭 변조) 모듈과 스위칭모드로 제어하는 기본적인 승압과 강압컨버터를 연구하고, 전기적 특성을 SPICE로 시뮬레이션을 수행하며, 전력의 효율을 각 소자의 변화와 사양에 따라 분석하는데 있다.

• Journal of Electrochemical Science and Technology
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• 제1권2호
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• pp.75-80
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• 2010

We report Co-tetramethoxyphenylporphyrin on carbon particles (Co-TMPP/C) as a non-Pt catalyst for tri-iodide reduction in dye-sensitized solar cells (DSSCs). The presence of well-dispersed carbon and cobalt source in the catalyst surface is confirmed by transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray analysis. In the C 1s, Co 2p, and N 1s peaks measured by X-ray photoelectron spectroscopy, the C-N, Co-$N_4$, and N-C are assigned to the component at 285.7, 781.8, and 401 eV, respectively. Especially, the Co-TMPP/C shows improved current density, diffusion coefficient, and charge-transfer resistance in the ${I_3}^-/I^-$ redox reaction compared to conventional catalysts. Furthermore, in the DSSCs performance, the Co-TMPP/C shows increased short circuit current density, higher open circuit voltage, and improved cell efficieny in comparison with Pt/C.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 추계학술대회 논문집
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• pp.7-11
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• 2008

형광등은 방전등의 일종으로 방전현상을 이용하여 전기에너지를 빛으로 변환하는 광원으로 램프의 점등 시에 나타나는 부저항 특성 때문에 반드시 점등회로를 필요로 한다. 방전등의 광원특성과 안정기의 변환특성은 밀접한 관련을 가지고 있다. 따라서 양 특성의 정합성립을 위하여 사용조건 및 경제성을 고려한 최적회로 설계지침을 내놓는 것은 매우 중요하다. 본 논문에서는 형광등용 전자안정기에 있어 부하인 형광램프의 수명말기에 나타나는 화재, 광효율 저감 등 여러 가지 문제점을 개선할 수 있는 수명말기 검측과 수명말기 표시기능 개발에 대하여 고찰해본다.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.120-129
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• 1997

The fire protective coating can reduce certain damages in case of fire, also conserve energy by thermal insulation and prevent corrosion and errosion in normal daily life by means of blocking thermal transfer, that were generally made of organic, inorganic and metallic materials as adiabatic coating. In case of inorganic material such as soluble silicate, it produces less toxic substances which are exposed to Ore, and have a plenty of raw material. Also inorganic thermal insulator is good in heat resistance. To develope such a excellent inorganic thermal insulator, the study of fire protective coating using the alkali silicate is necessary The principle of intumescence for alkali silicate is from rapid evolution of water in the coating material, the quantity of water in it is of course influenced on the degree of intumescence. The phenomenon of intumescence in ternary silicate is increased as the radius of ion is bigger, and this is caused by evolution of so many kinds of water. The individual degree of intumescence is ordered like this ; $K^+$ > $Na^+$ > $Li^+$ . The best protection effect is similarity found to intumescence of ternary silicate. The result of X-ray diffraction analysis indicates that $KHSi_2O_5$ is an important ingredient in K-silicate.

• Journal of Electrochemical Science and Technology
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• 제10권1호
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• pp.89-97
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• 2019

As a promising candidate for anode materials in lithium ion battery (LIB), tungsten trioxide ($WO_3$) and tungsten disulfide ($WS_2$) nanocrystals were synthesized, and their electrochemical properties were comprehensibly studied using a half cell. One-dimensional $WO_3$ nanowires with uniform diameter of 10 nm were synthesized by hydrothermal method, and two-dimensional (2D) $WS_2$ nanosheets by unique gas phase sulfurization of $WO_3$ using $H_2S$. $WS_2$ nanosheets exhibits uniformly 10 nm thickness. The $WO_3$ nanowires and $WS_2$ nanosheets showed maximum capacities of 552 and $633mA\;h\;g^{-1}$, respectively, after 100 cycles. Especially, the capacity of $WS_2$ is significantly larger than the theoretical capacity ($433mA\;h\;g^{-1}$). We also examined the cycling performance using a larger size $WO_3$ and $WS_2$ nanocrystals, showing that the smaller size plays an important role in enhancing the capacity of LIBs. The larger capacity of $WS_2$ nanosheets than the theoretical value is ascribed to the lower charge transfer resistance of 2D nanostructures.