• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.215-219
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• 2020

In this study, nanoporous iron oxide layers were fabricated by the anodization of 304 series stainless steel. K₂HPO₄/glycerol solution was used as an electrolyte for anodization. We investigated the anodization behavior according to various parameters such as electrolyte concentration, reaction temperature, applied voltage, and reaction time. As a result of anodization, we confirmed that the anodic growth rate of oxide layer on 304 series stainless steel increased with increasing the electrolyte temperature and applied potential. In order to form well-ordered porous nanostructures, the electrolyte temperature was at 160 ℃, and the applied potential was at 30 V in 10 wt% K₂HPO₄/glycerol electrolyte.

• Membrane Journal
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• v.18 no.4
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• pp.274-281
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• 2008

Covalent-crosslinked sulfonated poly(arylene ether sulfone) (SPAES) copolymers were synthesized copolymerization technique and additionally crosslinked with divinylbenzene (DVB). To optimize the reaction condition, a concentration of crosslinking agent and a reaction time were varied in the ranges of $30{\sim}90\;v/v%$ and $30{\sim}720\;min$. The properties of the crosslinked membranes were investigated by SEM, TGA and the measurement of proton conductivity. It was found that the proton conductivity of crosslinked membranes decreased depending on a degree of crosslinking while water uptake and methanol permeability reduced.

• Membrane Journal
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• v.26 no.6
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• pp.432-448
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• 2016

In the last decade, various types of energy harvesting and conversion systems based on ion exchange membranes (IEMs) have been developed for eco-friendly power generation and energy-grid systems. In these membrane-based energy systems, high ion selectivity and conductivity properties of IEMs are critical parameters to improve efficiency of the systems such as proton exchange membrane fuel cells, anion exchange membrane fuel cells, redox flow batteries, water electrodialysis for hydrogen production, and reverse electrodialysis. This article suggests variable approaches to overcome trade-off limitation of polymeric membrane ion transport properties by reviewing various types of composite ion-exchange membranes including novel inorganic-organic nanocomposite membrane, surface modified membranes, cross-linked and pore-filled membranes.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.158-158
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• 1999

NiO 박막은 전자비임증착법과 RF-스퍼터링법으로 제작하여 박막의 성능을 평가하였다. NiO 박막의 성능평가를 위한 착색과 탈색은 전기적 착색셀을 제작하여 순환전압전류법으로 KOH 전해질 내에서 반복수행하였으며 성능이 퇴화된 박막의 투과율은 가시광선 분광기로 측정하였다. XPS에 의한 분석결과 막의 낱알 내부보다 낱알 표면에 많은 산소가 포함될수 있음을 알 수 있었다. KOH 전해질 속에서 사이클이 반복 수행된 막의 표면 낱알의 형태는 변하였으며, 3$\times$10-4mbar에서 제작된 시료가 막의 안정성이 좋았다. 제작 방법에 다라 막에 주입 및 추출되는 전하밀도와 투과율의 차이가 나타났고, 니켈 산화물 박막의 성능평가를 하기 위해 착색효율을 계산하였다. 기판물질인 IT(indium tin oxide)의 전기적 착색성과 전해질이 전기적 착색성에 미치는 영향에 대해서도 논의되었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.873-877
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• 2006

[ $Ta_2O_5$ ] 절연막을 제조하기 위하여 ANODE OXIDATION 공정을 수립하였다. Electrolyte에서의 전압강하는 정전류 모드에서 예상되는 전압의 변화에는 영향을 주지 않지만, 정전압 모드에서 전류의 변화에 영향을 주는 것으로 나타났다. 전해질에서의 전압 강하가 음극산화 전압과 같은 값을 갖는 경우, 전류는$Ta_2O_5$/전해질 계면에서의 전압강하가 증가함에 따라 logarithmic한 형태로 변화하는 것으로 나타났다. 음극 $Ta_2O_5$ 절연막 제조공정에 있어서 전해질에서의 전압 강하는 정전류 모드에서 두께의 손실을 발생시키지만, 정전압 모드에서 다시 복원되기 때문에, 최종 두께는 음극산화 전압에 비례하는 것으로 나타났다. 음극 $Ta_2O_5$ 절연막의 전기적 특성을 조사한 결과, 항복전압은 Electrolyte의 농도와 Anodization Current에 반비례하는 것으로 나타났다. 절연막의 두께가 $1500\AA$일 때 Breakdown Voltage는 350volt. 유전상수는 29로 측정되었다.

• Proceedings of the Membrane Society of Korea Conference
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• spring
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• pp.39-52
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• 2005

• Journal of the Korean Chemical Society
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• v.59 no.5
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• pp.413-422
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• 2015

Proton exchange membrane (PEM), which transfers proton from the anode to the cathode, is the key component of the proton exchange membrane fuel cell (PEMFC). Nafion is widely used as PEM due to its high proton conductivity as well as excellent chemical and physical stabilities. However, its high cost and the environmental hazards limit the commercial application in PEMFCs. To overcome these disadvantages, various alternative polymer electrolytes have been investigated for fuel cell applications. We used densely sulfonated polymers to maximize the ion conductivity of the corresponding membrane. To overcome high swelling, dipole-dipole interaction was used by introducing nitrile groups into the polymer backbone. As a result, physically-crosslinked membranes showed improved swelling ratio despite of high water uptake. All the membranes with different hydrophilic-hydrophobic compositions showed higher conductivity, despite their lower IEC, than that of Nafion-117.

• Membrane Journal
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• v.16 no.4
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• pp.276-285
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• 2006

Acid-doped sulfonated poly(aryl ether benzimidazole) (S-PAEBI) copolymers were synthesized by a direct polymerization technique and a doping with phosphoric acid as a dopant, and the polymer electrolyte membranes were fabricated from them by a solution casting method. To optimize the reaction condition, the degree of sulfonation and doping level were varied in the ranges of $0{\sim}60%\;and\;0.7{\sim}5.7$, respectively. Physiochemical properties of the doped membranes were investigated by AFM, TGA and the measurement of proton conductivity. It was found that proton conductivities depend on doping levels of membranes. Conductivity determined at the condition of $130^{\circ}C$ and no humidity was $7.3{\times}10^{-2}S/cm$ for the $H_3PO_4$-doped PAEBI membrane with a doping level of 5.7.

• Membrane Journal
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• v.32 no.6
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• pp.427-441
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• 2022

Polymer electrolyte membrane (PEM) serving as a separator that can prevent the permeation of unreacted fuels as well as an electrolyte that selectively transports protons from the anode to the cathode has been considered a key component of polymer electrolyte membrane fuel cell (PEMFC). The perfluorinated sulfonic acid-based PEMs, represented by Nafion®, have been commercialized in PEMFC systems due to their high proton conductivity and chemical stability. Nevertheless, these PEMs have several inherent drawbacks including high manufacturing costs by the complex synthetic processes and environmental problems caused by producing the toxic gases. Although numerous studies are underway to address these drawbacks including the development of sulfonated hydrocarbon polymer-based PEMs (SHP-PEMs), which can easily control the polymer structures, further improvement of PEM performances and durability is necessary for practical PEMFC applications. Therefore, this study focused on the various strategies for the development of SHP-PEMs with outstanding performance and durability by 1) introducing cross-linked structures, 2) incorporating organic/inorganic composites, and 3) fabricating reinforced-composite membranes using porous substrates.

• KSBB Journal
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• v.4 no.2
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• pp.150-156
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• 1989

The chaacterisitics of a commercial membrance-coverd electrode in air-saturated saline solution were investigated in terms of a steadystate one-dimensional model. The electrode system miiersed in an aqueous medium consists of three layers: an external concentration boundary layer, a membrance, and an inner electrolyte layer. The membrance can be permeabld to the water and impermeable to the ionic species. In stationary midium, the water migrates from the external medium to the inner electrolyte layer until a thermodynamic equilibrium is reached. In a following midium, however, there is a reverse direction of water movement due to the hyrodynamic pressure differential until both thickness of the electrolyte layer and the membrance are equal.