• Composites Research
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• v.28 no.5
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• pp.265-269
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• 2015

Development of simple and efficient method for large-scale production of mechanically strong and electrically conductive graphene fiber is highly desirable for practical applications, such as fiber-reinforced composites, wearable electronics, and electromagnetic irradiation shielding. Here, we present a facile approach for the preparation of amine-functionalized graphene fibers by simple wet-spinning of diamine-functionalized graphene oxide (GO-$NH_2$), which is used because of its synthetic convenience, good dispersity, and scalable production with low cost. The amine-functionalized graphene fiber shows high electrical and mechanical properties compared to pristine graphene oxide fiber due to the electrostatic interaction between amine groups and electronegative functional groups of graphene oxide.

• Membrane Journal
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• v.29 no.6
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• pp.299-307
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• 2019

Photocatalysis is an environment friendly technique for degrading organic dyes in water. Tungsten oxide is becoming an active area of research in photocatalysis nanomaterials for having a smaller bandgap than the previously favored titanium dioxide. Synthesis of hierarchical structures, doping platinum (Pt), coupling with nanocomposites or other semiconductors are investigated as valid methods of improving the photocatalytic degradation efficiency. These impact the reaction by creating a redshift in the wavelength of light used, effecting charge transfer, and the formation/recombination of electron-hole pairs. Each of the methods mentioned above are investigated in terms of synthesis and photocatalytic efficiency, with the simplest being modification on the morphology of tungsten oxide, since it does not need synthesis of other materials, and the most efficient in photocatalytic degradation being complex coupling of metal oxides and carbon composites. The photocatalysis technology can be incorporated with water purification membrane by modularization process and applied to advanced water treatment system.

• Journal of Hydrogen and New Energy
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• v.20 no.6
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• pp.512-518
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• 2009

Mg 및 Mg합금은 수소 저장량이 7.6wt.%로 비교적 높고 자원도 풍부하여 값이 싼 장점을 가지고 있으나 산화반응성이 높고 활성화 에너지가 크기 때문에 반응온도가 높고 반응시간이 긴 단점을 가지고 있다. 이러한 단점을 극복하기 위해 일반적으로 Mg 및 Mg합금의 표면 개질화, 금속간 화합물 형성, 전이금속 첨가에 대한 연구가 활발히 진행되고 있다. 본 연구에서는 전이금속인 Nb를 촉매제로 사용하여 수소화 특성을 개선하고자 기계적 합금화법(MA;Mechanical Alloying)을 실시하여 복합재료를 합성한 후 수소화 반응을 평가하였다. XRD, SEM, TEM, PSA, TG/DSC 분석을 수행하였으며 Sievert's 형 PCT를 이용하여 온도 및 압력 변화에 따른 특성평가를 하였다. 전이금속인 Nb의 첨가로 수소화 반응개시온도가 낮아지고 수소 저장량이 향상되는 거동을 보였다. 특히, 5mass%Nb가 10mass%Nb 보다 수소 저장량 및 반응속도가 좋은 결과를 보였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.663-667
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• 2005

Surface modified carbon nanotubes were applied into the epoxy composites to investigate its tribological property. Carbon nanotubes reinforced epoxy composites were fabricated by casting. Effects to the tribological property of loading concentrations and types of surface modification of carbon nanotubes were investigated under sliding condition using linear reciprocal sliding wear tester. The results show that the small amount of carbon nanotubes into the epoxy exhibited lower weight loss than the pure epoxy. It is concluded that the effect of an enormous aspect ratio of carbon nanotubes surface area which wider than conventional fillers that react as interface for stress transfer. As increased the contents of carbon nanotubes, the weight loss from the wear test was reduced. And the surface modified carbon nanotubes show better tribological property than as produced carbon nanotubes. It is due that a surface modification of carbon nanotubes increases the interfacial bonding between carbon nanotubes and epoxy matrix through chemical bonding. Changes in worn surface morphology are also observed by optical microscope and SEM for investigating wear behaviors. Carbon nanotubes in the epoxy matrix near the surface are exposed, because it becomes the lubricating working film on the worn surface. It reduces the friction and results in the lower surface roughness morphology in the epoxy matrix as increasing the contents of the carbon nanotubes.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.33-35
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• 2012

본 연구에서는 전이금속 Cu, Mn이 함침된 제올라이트를 사용하여 일산화탄소의 흡착능을 연구하였다. 금속 복합 산화물촉매 제조는 Cu, Mn을 서로 다른 비율로 물리 혼합하여 지지체에 담지하였다. 제올라이트 분자체는 상용 13X를 사용하였다. 함침방법은 과잉용액 함침법을 사용하였고, 건조 후 소성 하여 산화물 형태로 담지하였다. 합성된 개질 흡착제의 표면특성 분석은 $N_2$흡착 및 탈착곡선을 통한 질소흡착 특성 분석으로 기공크기, 기공분포, 비표면적을 구하였으며, FT-IR, X-선 회절분석, 전자주사현미경, $NH_3$-TPD/TPR 으로 특성을 분석하였다. 흡착 실험은 고정층 반응기에서 수행하였으며, 내경 4 mm 석영관에 흡착제를 충진하고 흡착파과곡선을 Gas Chromatograph로 측정하여 Cu-Mn 제올라이트 촉매의 일산화탄소 흡착 성능을 연구하였다. Cu-Mn 함량 비율과 흡착조업조건에 따른 흡착능을 측정하여 최적 흡착조건을 구하였다.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.3
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• pp.183-189
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• 2005

The effects of duplex-treatment of plasma carburization and CrN coating onto Ti-6Al-4V alloy on its creep properties were investigated by means of a constant stress creep tester. Applying duplex-treatment, specimens having an inner carburized layer of about $150{\mu}m$ in depth and outer CrN layer of about $7.5{\mu}m$ in thickness were prepared. The hardness of duplex-treatment surface was about 1,960 VHN. It also appeared that the duplex-treatment improved the roughness of the surface significantly; $Ra=0.045{\mu}m$ for treated alloy while $Ra=0.321{\mu}m$ for untreated alloy. The steady-state creep behaviors were investigated in a temperature range of $510{\sim}550^{\circ}C$ ($0.42{\sim}0.44T_m$) under an applied stress range of 200~275 MPa. The stress exponent, n, was derived assuming the power law creep behavior. The surface treatment showed a decrease in a value from 9.32 (untreated) to 8.79 (treated). Also the activation energy obtained from an Arrhenius plot increased from 238 to 257 kJ/mol.

• Composites Research
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• v.23 no.5
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• pp.1-7
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• 2010

To increase the adhesive strength of acrylonitrile butadiene rubber(NBR) and steel plate, the atmospheric pressure flame plasma(APFP) treatment device is applied. The effect of various conditions(processing velocity and distance) is experimentally investigated to ascertain the optimum conditions to yield the best adhesive properties. It is found that the optimum distance between burner port and steel plate is 40mm and the optimum processing velocity is 50m/min at given condition. When the surface is coated twice with the bonding agent, the adhesion strength of APFP treated steel plate is increased to about 20.5%. It suggests that the surface modification of steel by flame plasma treatment at atmospheric pressure is a proper and applicable method to improve the adhesion strength between steel and rubber.

• Tribology and Lubricants
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• v.18 no.1
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• pp.61-67
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• 2002

The objective of the present study was to investigate the characteristics of the friction and wear according to the amount of ion-irradiation for the carbon fiber reinforced plastic (CFRP). Unidirectional carbon fiber reinforced composites were fabricated with epoxy resin as a matrix and carbon fiber as a reinforcement, and its surface was modified by the ion-assisted reaction. When the amount of ion-irradiation was $1{\times}10^{16}$ $ions/cm^{2}$. the friction coefficients of composites were about 0.1 and the wear mode was stable. whereas, the friction coefficient of non-treatment composites were about 0.16 and the wear mode was very unstable. But if the amount of ion-irradiation was $5{\times}10^{16}$ $ions/cm^{2}$, the friction coefficients were higher rather than that of $1{\times}10^{16}$ $ions/cm^{2}$ Consequently. the amount of ion-irradiation was not in proportion to the friction coefficients, and it was conformed that the optimal conditions would exist between both of them.

• Membrane Journal
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• v.23 no.2
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• pp.136-143
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• 2013

Recently, a novel coating method using an aqueous doapmine solution was proposed, the deposited coating was found to have extraordinarily strong-adhesion to numerous materials such as metal and polymers. However, it has suffered from many controversy in scientific fields due to its final structure and deposited mechanisms. Here, we have proposed a new structure for final dopamine product coupling with solid state spectroscopic, thermal behavior, and gas transport behaviors of dopamine coated microporous polyethersulfone membranes. In its final analysis, the results represented that it is a supramolecular aggregated of monomers consisting of 5,6-dihydroxyindoline and its derivative in contrast to previously proposed polymeric structure.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.58-58
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• 2011

현 의류 섬유산업의 트렌드는 친환경, 무공해, 인체친화, 고감성, 고급스러움 등을 표현할 수 있는 제품으로의 전환이 이루어지고 있으며, 최근 부드럽고, 편안하고, 모던한 특징 및 내추럴한 느낌을 나타내는 천연섬유에 대한 요구가 더욱 늘어나고 있다. 양모 섬유는 천염섬유 중 많은 비중을 차지하고 있는 단백질 섬유로서, 이를 이용한 다양한 직물과 의류제품은 국내외적으로 유명 브랜드 바이어와 지속적으로 내수와 수출이 이루어지는 대표적 섬유이다. 그러나 양모 소재에 특유의 구조와 형태로 소재간 섬도차로 인해 고급섬유에의 복합시 물리적, 감성적 이질감으로 상품화가 제한되고 있으며, 소비자 및 바이어들은 기존 보다 더욱 부드러운 고급감의 양모소재를 선호하고 있다. 이에 천염섬유 중에서도 세섬도 생산의 한계가 있는 양모섬유에 대해 양모섬유의 끝단을 마이크로 분활화 및 세섬화를 가능하게 함으로서 새로운 고감성 및 고급감을 부여할 수 있을 것이며, 본 연구에서는 산 및 초음파 등의 물리화학적 분할 기술을 적용하여 부분적 피브릴화 세섬화된 양모소재에 대한 염가공 특성을 기존 양모소재와 비교 함으로서 개질 양모소재의 제품화 실용성 여부를 검토하였다.