• Carbon letters
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• 제13권4호
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• pp.230-235
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• 2012

In this study, reduced graphene oxide/polyimide (r-GO/PI) composite films, which showed significant enhancement in their electrical conductivity, were successfully fabricated. GO was prepared from graphite using a modified Hummers method. The GO was used as a nanofiller material for the preparation of r-GO/PI composites by in-situ polymerization. An addition of 20 wt% of GO led to a significant decrease in the volume resistivity of composite films by less than nine orders of magnitude compared to that of pure PI films due to the electrical percolation networks of reduced GO created during imidization within the films. A tensile test indicated that the Young's modulus of the r-GO/PI composite film containing 20 wt% GO increased drastically from 2.3 GPa to 4.4 GPa, which was an improvement of approximately 84% compared to that of pure PI film. In addition, the corresponding tensile strength was found to have decreased only by 12%, from 113 MPa to 99 MPa.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.548-548
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• 2012

Thermomechanical and surface chemical properties of composite films of poly(D, L-lactic-co-glycolic acid) (PLGA) were significantly improved by the addition of graphene oxide (GO) nanosheets as nanoscale fillers to the PLGA polymer matrix. Enhanced thermomechanical properties of the PLGA/GO (2 wt.%) composite film, including an increase in the crystallization temperature and reduction in the weight loss, were observed. The tensile modulus of a composite film with increased GO fraction was presumably enhanced due to strong chemical bonding between the GO nanosheets and PLGA matrix. Enhanced hydrophilicity of the composite film due to embedded GO nanosheets also improved the biocompatibility of the composite film. Improved thermomechanical properties and biocompatibility of the PLGA composite films embedded with GO nanosheets may be applicable to biomedical applications such as scaffolds.

• 한국재료학회지
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• 제24권4호
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• pp.180-185
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• 2014

The current concern about these materials ($MoSi_2$ and $NbSi_2$) focuses on their low fracture toughness below the ductile-brittle transition temperature. To improve the mechanical properties of these materials, the fabrication of nanostructured and composite materials has been found to be effective. Nanomaterials frequently possess high strength, high hardness, excellent ductility and toughness, and more attention is being paid to their potential application. In this study, nanopowders of Mo, Nb, and Si were fabricated by high-energy ball milling. A dense nanostructured $MoSi_2-NbSi_2$ composite was simultaneously synthesized and sintered within two minutes by high-frequency induction heating method using mechanically activated powders of Mo, Nb, and Si. The high-density $MoSi_2-NbSi_2$ composite was produced under simultaneous application of 80MPa pressure and an induced current. The sintering behavior, mechanical properties, and microstructure of the composite were investigated. The average hardness and fracture toughness values obtained were $1180kg/mm^2$ and $3MPa{\cdot}m^{1/2}$, respectively. These fracture toughness and hardness values of the nanostructured $MoSi_2-NbSi_2$ composite are higher than those of monolithic $MoSi_2$ or $NbSi_2$.

• 대한금속재료학회지
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• 제47권11호
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• pp.754-758
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• 2009

Dense $5Cu_{0.6}Fe_{0.4}-Al_{2}O_{3}$ composite was consolidated from mechanically synthesized powders by high frequency induction heating method within 2 min. Consolidation was accomplished under the combined effects of a induced current and mechanical pressure. Dense $5Cu_{0.6}Fe_{0.4}-Al_{2}O_{3}$ with relative density of up to 95% was produced under simultaneous application of a 80 MPa pressure and the pulsed current. Fracture toughness and hardness of the composite are $7.6MPa{\cdot}m^{1/2}$ and $844kg/mm^{2}$ respectively.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.601-601
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• 2006

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.103-103
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• 2006

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1467-1469
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• 2002

This paper aims to investigate the characteristics of braided thermoplastic and thermosetting composite and pressure relief for polymer arrester. In general, braided composite has potential for improved impact and delamination resistance. Manufacturing processes of the braided composite could also be automated and could potentially lead to lower costs. Therefore, in consideration of characteristics of pressure relief for polymer arrester, the fabric pattern of braided composite was studied. And polymer arrester module was manufactured with braid.

• Advanced Composite Materials
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• 제16권4호
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• pp.349-360
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• 2007

Recently, natural fiber reinforced composite is attracting attention and considered as an environmentally friendly material. Usually cellulosic fibers are used to reinforce the composites, but some protein fibers such as silk and wool serve the same purpose. In this paper, we proposed a method of producing artistic composite from artistic fabric by using silk fiber reinforced biodegradable plastic, which is designated as 'silk composite', for reinforcement. In order to expand applications of the silk composite, we performed the compression molding of decorative laminates with woody material, which was selected as a core material, and examined the properties of molded decorative laminates with various content of the silk composite. Since plywood and medium-density fiberboard (MDF) are widely used for decorative laminates, we selected them as core materials. As a result, flexible decorative laminates with high flexural strength were obtained by compounding the silk composite with wood materials.

• Corrosion Science and Technology
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• 제8권1호
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• pp.27-39
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• 2009

Non metallic composite materials, for example, GECM(graphite epoxy composite material) show high specific strength because of low density. These kinds of non metallic composite materials improved the structural effectiveness and operation economics. However, if these materials contacted several metals, corrosion can be arisen since non metallic composite materials have electrical conductivity. This paper dealt with galvanic corrosion between graphite epoxy composite material and several metals. Base on the electrochemical galvanic corrosion test between GECM and metals, corrosion current of carbon steel and aluminium increased with time but corrosion current of stainless steels and titanium decreased and galvanic potential increased. This behavior shows the galvanic corrosion depends upon the presence of passive film. Also, galvanic effect of GECM coupled with ferrous alloys and non-ferrous alloys was lower than that of 100% graphite, which is attributed to lower exposed area of graphite fiber in the GECM than apparent area of the GECM specimen used for the calculation of galvanic current in this work.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 춘계학술발표대회 논문집
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• pp.114-118
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• 1999