• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.208-211
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• 2007

Polymer Electrolyte Membrane fuel cell(PEMFC)의 촉매로는 주로 carbon을 지지체로 사용한 Pt/C 흑은 Pt alloy/C을 사용하게 된다. 이때 PEMFC의 상용화에 있어 촉매의 안정성은 상용화 실현에 있어 중요한 요인으로 인식되고 있다. 촉매의 성능 저하는 Pt의 활성 면적(Active surface area)의 감소가 원인으로 얘기되어 지고 있으며 이는 지지체로 사용한 탄소에 나노 크기로 분산되어 있던 Pt 입자가 커지면서 활성 면적이 감소되어 지기 때문이다. 이번 연구에서는 상용 Pt/C를 사용하여 Cyclic Voltammetry(CV)의 장기간 운전 및 다양한 조건 변화를 통하여 Pt입자의 크기 증가에 미치는 요인에 대한 연구를 진행하였다. 이와 더불어 Linear Sweep Voltammety(LSV), TEM, 등을 통한 분석이 진행되었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.140-140
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• 2009

The polymer electrolyte membrane fuel cell(PEMFC) with the advantages of low-operating temperature, high current density, low cost and volume, fast start-up ability, and suitability for discontinuous operation becomes the most reasonable and attractive power system for transportation vehicle and micro-grid power plant in a household. 200W PEM-type FCs system was integrated by this study, then the electrical characteristics and diagnosis of the fuel cell were analyzed with variations on mass flow rate and stack temperature. The ranges of the variations are $20{\sim}70^{\circ}C$ on stack temperature and 1~8L/min on $H_2$ volume.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.153-156
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• 2012

The optimization and integration of a fuel cell were performed to improve the performance and reliability of the fuel cell in this paper. To improve the performance of the PEMFC, current and voltage of the fuel cell were measured using an electrical load, and the results was compared and analyzed with the data of a commercial fuel cell. Based on the above results, a controller for a fuel cell UAV applications was designed, and the fuel cell control algorithm was developed to optimize the performance of the fuel cell UAV.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.1
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• pp.36-41
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• 2016

The development need of new renewable energy is more and more important to resolve exhaustion of chemical fuels and environmental pollution. Polymer electrolyte membrane fuel cell has been widely studied to the extent that it can be used commercially. But there are many problems to be solved. One of them is to enhance the stability of fuel cell stacks. This paper proposes a new fault diagnosis method using Least Square Method (LSM) which is one of parameter estimation methods. The proposed method extracts equivalent circuit parameters from on-line measurements. Parameters of the circuit are estimated according to normal and abnormal states using simulation. The variation of parameters estimated in each states enables the estimation of state in fuel cells. Thus the LSM presented can be a suitable on-line parameter estimation method in PEMFC.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.438-442
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• 2006

The degradation of Nafion membrane by hydrogen peroxide was investigated in polymer electrolyte membrane fuel cell (PEMFC). Degradation tests were carried out in a solution of $10{\sim}30%$ hydrogen peroxide containing 4ppm $Fe^{2+}$ ion which is well known as Fenton's reagent at $80^{\circ}C$ for 48hr. Characterization of degraded membranes were examined through the IR, Water-uptake, Ion exchange capacity, mechanical strength and $H_2$ permeability. After degradation, C-F, S-O and C-O chemical bonds of membrane were broken by radical formed by $H_2O_2$ decomposition. Breaking of C-F bond which is the membrane backbone reduced the mechanical strength of Nafion membrane and hence induced pinholes, resulting in increase of $H_2$ crossover through the membrane. Also the decomposition of C-O and S-O, side chain and terminal bond of membrane, decreased the ion exchange capacity of the membrane.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.2
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• pp.144-149
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• 2017

A proton-conducting bisphenylpropaned sulfonated fluorinated blockcopolymer (BPSFBC) was synthesized. Five kinds of polymer electrolyted composite membranes were preparated by incorporating silica ($SiO_2$) with various weight ratio. And their characteristics were investigated by FT-IR (fourier transform infrared), $^1H-NMR$ ($^1H$ nuclear magnetic resonance), TGA (thermogravimetric analysis), water uptake, FE-SEM (field emission scanning electron microscopes), and ion conductivity properties. The water uptake and ion conductivity were increased until 9 wt% $SiO_2$, and then decreased. The maximum proton conductivity equal to $52mScm^{-1}$ was measured for the BPSFBC/$SiO_2$-9 composite membrane at $90^{\circ}C$ and 100% relative humidity. From the measured results, it is distinct that the manufactured composite membrane BPSFBC/$SiO_2$-9 can be considered as a polymer membrane suitable for a fuel cell electrolyte.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1577-1582
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• 2010

A 20 wt % Pt/C is fabricated and characterized for use as the cathode catalyst in a polymer electrolyte membrane fuel cell (PEMFC). By using the polyol method, the fabrication process is optimized by modifying the carbon addition sequence and precursor mixing conditions. The crystallographic structure, particle size, dispersion, and activity toward oxygen reduction of the as-prepared catalysts are compared with those of commercial Pt/C catalysts. The most effective catalyst is obtained by ultrasonic treatment of ethylene glycol-carbon mixture and immediate mixing of this mixture with a Pt precursor at the beginning of the synthesis. The catalyst exhibits very uniform particle size distribution without agglomeration. The mass activities of the as-prepared catalyst are 13.4 mA/$mg_{Pt}$ and 51.0 mA/$mg_{Pt}$ at 0.9 V and 0.85 V, respectively, which are about 1.7 times higher than those of commercial catalysts.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.4
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• pp.310-315
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• 2012

A simple drying process was developed for the preparation of a Pt/Nafion self-humidifying membrane to be used for a proton-exchange membrane fuel cell (PEMFC). Platinum (II) bis (acetylacetonate), $Pt(acac)_2$ was sublimed, penetrated into the surface of a Nafion film and then reduced to Pt nanoparticles simultaneously without any support of a reducing agent in a glass reactor at $180^{\circ}C$ for 15 min. The process was carried out in $N_2$ atmosphere to prevent the oxidation of Pt nanoparticles at high temperature. The morphology and distribution of the Pt nanoparticles were observed by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS), and we found that the average Pt particle size was ca. 3.7 nm, the penetration depth was ca. $17{\mu}m$. Almost all Pt nanoparticles were formed just beneath the surface and the number density decreased rapidly as the penetration depth increased. To estimate water absorption characteristics of the Nafion membranes, water uptake at an isothermal condition was measured by dynamic vapor sorption (DVS), and it was found that water uptake of the Pt/Nafion membrane was higher than that of the neat Nafion membrane.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1763-1770
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• 2013

A series of the block copolymers were successfully synthesized from post-sulfonated hydrophilic and hydrophobic macromers via three-step copolymerization. The degrees of sulfonation (DS) of the copolymers (10%, 30%, or 50%) were controlled by changing the molar ratio of the hydrophilic and hydrophobic parts. The resulting block copolymers were characterized by $^1H$ NMR and other technologies. The membranes were successfully cast using dimethyl sulfoxide (DMSO) solution at $100^{\circ}C$. The copolymers were characterized to confirm chemical structure by $^1H$ NMR and FT-IR. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) demonstrated that all sulfonated block copolymers exhibited good thermal stability with an initial weight loss at temperatures above $240^{\circ}C$. The membranes showed acceptable ion exchange capacity (IEC) and water uptake values in accordance with DS. The maximum proton conductivity was 184 mS $cm^{-1}$ in block copolymer-50 at $60^{\circ}C$ and 100% relative humidity, while the conductivity of Nifion-115 was 160 mS $cm^{-1}$ under the same measurement conditions. AFM images of the block copolymer membranes showed well separated the hydrophilic and hydrophobic domains. From the observed results it is that the prepared block membranes can be considered as suitable polymer electrolyte membranes for the application of polymer electrolyte membrane fuel cells (PEMFC).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.1
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• pp.86-93
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• 2007

The PEM (polymer electrolyte membrane) fuel cell is one of the promising fuel cell systems as a new small power generating device for automobiles and buildings. The optimal design of cooling plates installed between MEA (membrane electrode assembly) is very important to achieve high performance and reliability of the PEMFC because it is very sensitive to temperature variations. In this study, six types of cooling plate models for the PEMFC including basic serpentine and parallel shapes were designed and their cooling performances were analyzed by using three-dimensional fluid dynamics with commercial software. The model 3 designed by revising the basic serpentine model represented the best cooling performance among them in the aspect of uniformity of temperature distribution and thermal reliability, The serpentine models showed higher pressure drop than the parallel models due to a higher flow rate.