• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.196-200
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• 2018

In this study, the intermediate layer in Pd-based hydrogen separation membrane was synthesized to minimize the surface roughness and defects using powder-type and sol-type metal oxides. The surface properties and gas permeation characteristics were analysed by SEM and $N_2$ gas permeation test. The coating layer composed of sol type metal oxides has smooth surface, especially the layer coated by $TiO_2$ sol has little pin holes, cracks and defects. The binary layer composed of powder type and sol type metal oxides has similar flux characteristics to a single sol type layer. The Pd-based composite membrane improved by the binary intermediate layer exhibited $0.32mol/m^2s$ of the hydrogen permeation flux with a selectivity ($H_2/N_2$) of ~10,890 at 672 K and a pressure difference of 1 bar.

• Microbiology and Biotechnology Letters
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• v.20 no.4
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• pp.451-458
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• 1992

Pervaporation which is capable of removing ethanol selectively was adopted to reduce the ethanol inhibition and in situ recovery of ethanol in ethanol fermentation, The composite membrane made of silicone and polysulfone was used to separate the ethanol selectively. The ethanol selectivity of the membrane was about 4 and the total flux was 300 g/m2 h at 301:: and 10 mmHg for 25 g/l of feed concentration. Saccharomyces cerevisiae entrapped within Ca-alginate gels was employed for ethanol fermentations in a fluidized-bed bioreactor. The pervaporation membrane unit and fluidized-bed bioreactor were combined into one system. The proposed model equations for the combined system showed good accordances with the experimental results. It was found from the simulation results that the ethanol concentration in the broth for the combined system was lower than that for the continuous fermentation system without a membrane unit. Ethanol productivity can be thus increased by employing the combined system.

• Journal of Hydrogen and New Energy
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• v.17 no.2
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• pp.149-157
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• 2006

Hydrogen as new energy sources is highly efficient and have very low environmental emissions. The proton exchange membrane fuel cell (PEMFC) is an emerging technology that can meet these demands. Therefore, the preparation of stable polymeric membranes with good proton conductivity and durability are very important for hydrogen production via water electrolysis with PEM at medium temperature above $80^{\circ}C$. Currently Nafion of Dupont and Aciflex of Asahi, etc., solid polymer electrolytes of perfluorosulfonic acid membrane, are the best performing commercially available polymer electrolytes. However, these membrane have several flaws including its high cost, and its limited operational temperature above $80^{\circ}C$. Because of this, significant research efforts have been devoted to the development of newer and cheaper membranes. In order to make up for the weak points and to improve the mechanical characteristics with cross -linking, acid-base complexes were prepared by the combination PSf-co-PPSS-$NH_2$ with PEEK-$SO_3H$. The results showed that the proton conductivity decreased in 17.6% and 40% but tensile strength increased in 78% and 98%, about $20.65\;{\times}\;10^6N/m^2$, in comparison with SBPSf/HPA and SPEEK/HPA complex membrane.

• Polymer(Korea)
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• v.37 no.5
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• pp.649-655
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• 2013

In order to use as supporters for the reinforced composite fuel cell membrane, poly(acrylic acid)-grafted porous polytetrafluoroethylenes (PTFEs) were prepared via introduction of poly(acrylic acid) graft chains by a radiation grafting method. FTIR was utilized to confirm the successful introduction of poly(acrylic acid) graft polymer chains into the porous PTFEs. Contact angles were examined to observe the hydrophilicity of the surface of the prepared substrates. The result indicates that the hyrophilicity of the surface in the prepared substrates increases with an increase in the number of hydrophilic polymer chains. FE-SEM, gurley number, and tensile strength were also utilized to characterize the prepared substrates.

• Membrane Journal
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• v.17 no.2
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• pp.99-111
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• 2007

It is impossible to remove toxic organic substances that are recognized as a cancer caused suspicious element in drinking water using the conventional water purification method. This study introduces groundwater into a reaction chamber as an effective amount of water to process this water using a mixed method of AOP oxidation and M/F membrane and purifies it as a desirable level by artificially mixing such toxic substances in order to effectively process the water. Based on this fact, this study configures an optimal operation condition. The VOCs existed in toxic substances was investigated as a term of phenol and toluene, and agricultural chemicals were also investigated as a term of parathion, diazinon and carbaryl. The experiment applied in this study was performed using a single and composite soolution. In the operation condition applied to fully dissolve and remove such substances, the amount of $H_2O_2$ injected in the process was 150 mL of a fixed quantity, the value of pH was configured as $5.5{\sim}6.0$, the temperature was controlled as a range of $12{\sim}16^{\circ}C$, the dissolved amount of ozone was applied more than 5.0 mg/L, the reaction time was determined as an optimal condition, such as $30{\sim}40$ minutes, and the segregation membrane in the same reactor was determined for acquire water drinking of large quantity using a pore size of $0.45{\mu}m$ M/F membrane.

• Membrane Journal
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• v.32 no.6
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• pp.411-426
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• 2022

Energy plays a significant role in modern lifestyle because of our extensive reliance over energy-operating devices. Therefore, there is a need for alternative and green energy resources that can fulfill the energy demand. For this, fuel cell (FCs) especially anion exchange membrane fuel cells (AEMFCs) have gained tremendous attention over the other (FCs) due to their fast reaction kinetics without using noble catalyst and allow to use of cheaper polymers with high performance. But lack of highly conductive, chemically, and mechanically stable anion exchange membrane (AEM) still main obstacle to the development of high performance AEMFCs. Therefore, graphene-based polymer composite membranes came into the existence as AEMs for the FCs. The exceptional properties of the graphene help to improve the performance of AEMs. Still, there are lot of challenges in the graphene derivatives based AEMs because of their high tendency of agglomeration in polymer matrix which reduced their potential. To overcome this issue surface modification of graphene derivatives is necessary to restrict their agglomeration and conserved their potential features that can help to improve the performance of AEM. Therefore, this review focus on the surface modification of graphene derivatives and their role in the fabrication of AEMs for the FCs.

• Journal of Hydrogen and New Energy
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• v.22 no.3
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• pp.409-414
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• 2011

To promote the industry of PEMFC, the commercialization of its parts especially bipolar plate is needed. The bipolar plate is one of key parts for PEMFC, which occupies cost portion of 5~8% in the system. To replace the bipolar plate of machined graphite highly costly, the stamped thin matal or the molded carbon composite has been developed. According to the merits and demerits of each material and its forming process, the stamped metallic plate has been considered to the bipolar plate of PEMFC for automotive, and on the other hand, the molded composite plate has been considered to one for building applications. Hankook Tire Co., Ltd. has developed the carbon composite material and the manufacturing process for the bipolar plates. The developed bipolar plates were proved to be fully applicable to PEMFC of building applications in characteristics and performance, and so government strategic project to develop the mass-production technology for bipolar plates was started and is being conducted by the company. Through the government project for obtaining both the commercialization technology and production capacity for the bipolar plates, the price and the performance of domestic PEMFCs are expected to become competitive in international market.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.67-76
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• 2018

In this study, PDMS-HNT and PDMS-mHNT composite membranes were prepared by the addition of halloysite nanotube (HNT) and modified HNT (mHNT) to PDMS. To investigate the physico-chemical characteristics of composite membranes, analytical methods such as FT-IR, XRD, TGA, and SEM were utilized. The gas permeability and selectivity properties of $N_2$ and $CO_2$ were evaluated. In particular, the PDMS-HNT with 10 wt% HNT and PDMS-mHNT with 5 wt% mHNT showed the highest $CO_2/N_2$ selectivity and $CO_2$ permeability at $35^{\circ}C$, respectively. Overall, PDMS-HNT and PDMS-mHNT composite membranes improved the $CO_2/N_2$ selectivity compared to that of using PDMS membrane.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.3
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• pp.279-293
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• 2004

The analysis of linear static and free vibration problems of isotropic and laminated composite plates and shells is performed by the improved 9-node shell element with the new strain displacement relationship. In that relationship, the effect of new additional terms between the bending strain and displacement has been investigated in the warping problem. Natural co ordinate based strains, stresses and constitutive equations are used. The assumed natural strain method is used to alleviate both membrane and shear locking behavior from the element. The Lanczos method is employed in the calculation of the eigenvalues of laminated composite structures and the Gauss integration rule is adopted to evaluate the mass matrix. The numerical examples are compared with the analytical solutions to validate the current formulation and the results presented could be useful for the understanding of the behaviour of laminates under free vibration conditions.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.2
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• pp.114-121
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• 2014

Liquefied natural gas(LNG) cargo containment system(CCS) has the primary function of ensuring both adequate structural safety with respect to sloshing load which is defined as a violent behaviour of the liquid contents in CCS due to external forced motions and thermal insulation keeping natural gas below its boiling point. Among different LNG CCS types such as independent B-type and membrane ones, Mark III CCS is considered in this paper to perform its strength assessment. Mark III CCS plate is designed and constructed by stacking various non-metallic engineering materials such as plywood, triplex, reinforced PU foam that are supported by series of mastic upon inner steel hull structure. From the viewpoint of structural analysis, this plated structure is treated as a laminated composite structure showing complex structural behaviour under external load. Advanced finite element models of Mark III CCS plate is generated and used in conjunction with ultimate strength based failure criteria from laminated composite mechanics for the strength assessment. The strength assessment is performed within the initial failure state of Mark III CCS plate. Results provide failure details such as failure locations and loads. Finally obtained results are reviewed using the loads from acceptance criteria suggested by classification.