• Journal of Korean Society of Environmental Engineers
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• v.35 no.8
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• pp.586-591
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• 2013

This experiment was performed to enhance $CH_4$ purity of landfill gas by applying gas separator membrane for purified nitrogen gas production. 1:6 area ratios of $1^{st}$ to $2^{nd}$ membrane module was suitable for $CH_4$ recovery. After separation membrane system was installed, 249 tries were performed. Average permeability for $CH_4$ was 28.4% and for $CO_2$ was 94.3%. This can explain nitrogen gas separator membrane can be applied to collect $CH_4$ from LFG. However, nitrogen permeability only reached up to 16.5%. Therefore, the final purified landfill gas concentration was rounded up to 69.7% for $CH_4$, 4.3% for $CO_2$ and 26.0% for $N_2$. For the high degree of $CH_4$ purity, $N_2$ should be kept at least under 2.0% by controlling air inflow to landfill.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.5
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• pp.442-449
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• 2018

Research on High temperature polymer electrolyte fuel cell (HT-PEMFC) has actively been conducted all over the world. Since the HT-PEMFC can be operated at a high temperature of $120-180^{\circ}C$ using phosphoric acid-doped polybenzimidazole (PBI) electrolyte membrane, it has considerable advantages over conventional PEMFC in terms of operating conditions and system efficiency. However, If the thermal distribution is not uniform in the stack unit, degradation due to local reaction and deterioration of lifetime are difficult to prevent. The thin plate separator reduces the volume of the fuel cell stack and improves heat transfer, consequently, enhancing the cooling effect. In this paper, a large area flow field of thin plate separator for HT-PEMFC is designed and sub-stack is fabricated. We have studied stack performance evaluation under various operating conditions and it has been verified that the proposed design can achieve acceptable stack performance at a wide operating range.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.12
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• pp.761-768
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• 2016

Membranes are used to separate pure gas from gas mixtures. In this study, three different types of mass transport through a membrane were developed in order to investigate the gas separation capabilities of a membrane. The three different models typically used are a lumped model, a multi-cell model, and a discretization model. Despite the multi-cell model producing similar results to a discretization model, the discretization model was selected for this investigation, due to the cell number dependence of a multi-cell model. The mass transport model was then used to investigate the effects of pressure difference, flow rate, total exposed area, and permeability. The results showed that the pressure difference increased with the stage cut, but the selectivity was a trade-off for the increasing pressure difference. Additionally, even though permeability is an important parameter, the selectivity and stage cut of the membrane converged as permeability increased.

• Journal of the Korean institute of surface engineering
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• v.44 no.5
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• pp.173-178
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• 2011

Separator of stack in polymer electrolyte membrane fuel cell (PEMFC) is high cost and heavy. If we make it low cost and lighter, it will have a great ripple. In this study, low carbon steel is used as base metal of separator because the cost of low carbon steel is very cheaper commercial metal material than stainless steels, which is widely used as separator. Low carbon steel has not a good corrosion resistance. In order to improve the corrosion resistance and electrolytic conductivity, low carbon steel needs to be surface treated. We made Chromium electroplated layer of $5{\mu}m$, $10{\mu}m$ thickness on the surface of low carbon steel and it was nitrided for 2 hours at $1000^{\circ}C$ in a furnace with 100 torr nitrogen gas pressure. Cross-sectional and surface microstructures of surface treated low carbon steel are investigated using SEM. And crystal structures are investigated by XRD. Interfacial contact resistance and corrosion tests were considered to simulate the internal operating conditions of PEMFC stack. The corrosion test was performed in 0.1 N $H_2SO_4$ + 2 ppm $F^-$ solution at $80^{\circ}C$. Throughout this research, we try to know that low carbon steel can be replaced stainless steel in separator of PEMFC.

• Korean Journal of Metals and Materials
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• v.46 no.12
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• pp.817-822
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• 2008

Metal matrix composite (MMC) materials having low electrical contact resistance based on 316L stainless steel (STS) matrix alloy with $ZrB_2$ particles were fabricated for PEMFC (Polymer Electrolyte Membrane Fuel Cell) separator by powder metallurgy (PM). The effects of the boride particle addition into the matrix alloy on microstructure, surface morphology, and interfacial contact resistance (ICR) between the samples and gas diffusion layer (GDL) were investigated. Both conventional and PM 316L STS samples showed high ICR due to the existence of non-conductive passive film on the alloy surface. The addition of the boride particles, however, remarkably reduced ICR of the samples. SEM observation revealed that the boride particles were protruded out of the matrix surface and particle density existing on the surface increased with increasing the boride content, causing increase of the total contact area between the conductive particles and GDL. ICR of the samples also decreased with increasing the boride content resulted from the increased contact area.

• Membrane Journal
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• v.18 no.1
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• pp.75-83
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• 2008

In this research, the research for enhancing the stability at the mechanical strength and thermal stability and high power through the Direct Fluorination of the Polyethylene (PE, Asahi) for secondary battery was conducted. The surface of according to the fluorine gas exposure time and constructional change were observed through the scanning electron microscope image, and the contact angle. The mechanical property was confirmed through the tensile strength and surface hydrophilic property experiment. Charge and discharge experiment, the lifetime property, and the overcharge test were performed in order to confirm the electrochemical characteristic of produced and we confirmed at the high power that the stability about a temperature was improved.

• Journal of the Korean Solar Energy Society
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• v.34 no.4
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• pp.9-16
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• 2014

A proton exchange membrane is a core component in the proton exchange membrane fuel cell because the role of proton exchange membrane(PEM)is supplying proton conductivity to fuel cell, a gas separator, and insulating between an anode and cathode. Among various role of PEM, supplying proton conductivity is the most important and the proton conductivity is strongly related the structural evolution of PEM by hydration. Thus a lot of studies have done by past few decade based on small angle X-ray scattering and wide angle X-ray scattering for understanding morphological structure of the PEM. Resulting from these studies, several morphological models of hydrated PEM are proposed. Current sensing atomic force microscopy (CSAFM) can map morphology and conductance on the membrane simultaneously. It can be the best tool for studying heterogenous structured materials such as PEM. In this study, the hydration of the membrane is examined by using CSAFM. Conductance and morphological images are simultaneously mapped under different relative humidity. The conductance images, which are mapped from different relative humidity, are analyzed by statistical methode for understanding ionic channel variation in PEM.

• Membrane Journal
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• v.22 no.6
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• pp.395-403
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• 2012

R&D of Nanofiber membrane has been carried out in the various fields, gas, water treatment, energy, and etc, with the continuous growth of membrane technology. There are several preparation methods for nanofiber, i.e. drawing, template synthesis, phase separation, self-assembly, and electrospinning. However, an electrospinning has many advantages such as high productivity, low production cost, easy to select law material, high relative surface area, and easy to functionalize. Nanofiber has been used in the field of membrane technologies such as secondary battery and water treatment fields. For the secondary battery separator, the separators having a high power and high thermal stability can be developed with spread of nanofiber on the commercial PP or PE/PP separators. High functional membranes can be also developed by adding the functional additives like antibacterial materials in the nanofiber membrane. It can be expected the high value added with nanofiber membrane because of its diverse applications from the water treatment to the energy field and because of its various functional advantages.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.1
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• pp.99-99
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• 1993

혈액 및 생체시료 중 필수원소 혹은 독극성 원소의 극미량상분 정밀측정과 동위원소비율측정에 널리 사용되는 유도결합플라즈마 질량분석기(ICP-MS)의 기본원리를 소개하고 ICP-SM를 이용한 혈액중 낮은 ppb수준의 Cd, Hg 그리고 Pb의 정밀분석법을 소개한다. 혈액은 많은 양의 유기물을 포함하고 있으므로 digestion bomb에 질산과 과산화수소를 넣어 microwave oven에서 고온고압 상태로 분해시켜 많은 용액을 얻어 이 용액을 플라즈마에 주입시켜 분석한다. 그리고 수온은 tin(II) chloride 용액을 환원제로하여 생성시킨 수은원소증기를 membrane liquid-gas separator를 이용하여 뽑아내어 플라즈마에 주입시켜 낮은 ppt 수준의 검출한계를 얻는다. 또한 높은 정밀도와 정확도와 극미량 원소 측정에 사용되는 동위원소 회석법율 소개하고 실제 혈액분석에의 응용방법을 제시한다.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.233-236
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• 2004

Total impurity analysis of a primary standard solution is one of the essential procedures to determine an accurate concentration of the standard solution by the gravimetry. Bi impurity is determined in Pb standard solutions by inductively coupled plasma mass spectrometry (ICP-MS). The direct nebulization of the Pb standard solution produces a significant amount of the Pb matrix-induced molecular ions which give rise to a serious spectral interference to the Bi determination. In order to avoid the spectral interference from the interferent $^{208}PbH^+$, the hydride generation method is employed for the matrix separation. The Bi hydride vapor is generated by reaction of the sample solution with 1% sodium borohydride solution. The vapor is then directed by argon carrier gas into the ICP after separation from the mixture solution in a liquid-gas separator made of a polytetrafluoroethylene membrane tube. The presence of 1000 ${\mu}$g/mL Pb matrix caused reduction of the bismuthine generation efficiency by about 40%. The standard addition method is used to overcome the chemical interference from the Pb matrix. Optimum conditions are investigated for the hydride-generation ICPMS. The detection limit of this method is 0.5 pg/mL for the sample solutions containing 1000 ${\mu}$g/mL Pb matrix.