• International Journal of Concrete Structures and Materials
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• v.10 no.2
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• pp.249-256
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• 2016

This paper deals with the effects of silica fume content and polymer-binder ratio on the properties of ultrarapid-hardening polymer-modified mortar using silica fume and ethylene-vinyl acetate redispersible polymer powder instead of styrene-butadiene rubber latex to shorten the hardening time. The ultrarapid-hardening polymer-modified mortar was prepared with various silica fume contents and polymer-binder ratios, and tested flexural strength, compressive strength, water absorption, carbonation depth and chloride ion penetration depth. As results, the flexural, compressive and adhesion strengths of the ultrarapid-hardening polymer-modified mortar tended to increase as increasing polymer-binder ratio, and reached the maximums at 4 % of silica fume content. The water absorption, carbonation and chloride ion penetration resistance were improved according to silica fume content and polymer-binder ratio.

• Progress in Superconductivity and Cryogenics
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• v.16 no.1
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• pp.14-18
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• 2014

The mechanical, electrical and thermal characteristics of insulating materials may significantly affect the performance and reliability of electrical devices using superconductors. General method to provide insulating layer between coated conductors is wrapping coated conductor with Kapton tape. But uniform and compact wrapping without failure or delamination in whole coverage for long length conductor is not a simple task and need careful control. Coating of insulating layer directly on coated conductor is desirable for providing compact insulating layer rather than wrapping insulating layers around conductor. Ceramic added polymer has been widely used as an insulating material for electric machine because of its good electrical insulating properties as well as excellent heat resistance and fairy good mechanical properties. The insulating layer of coated conductor should have high breakdown voltage and possesses suitable mechanical strength and maintain adhesiveness at the cryogenic temperature where it is used and withstand stress from thermal cycling. The insulating and mechanical properties of polymer can be improved by adding functional filler. In this study, insulating layer has been made by adding ceramic particles such as $SiO_2$ to a polymer resin. The size, amount and morphology of added ceramic powder was controlled and their effect on dielectric property of the final composite was measured and discussed for optimum composite fabrication.

• Journal of Powder Materials
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• v.24 no.2
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• pp.147-152
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• 2017

Spherical-type zirconia granules are successfully fabricated by a spray-drying process using a water solvent slurry, and the change in the green density of the granule powder compacts is examined according to the organic polymers used. Two organic binders, polyvinyl alcohol (PVA) and 2-hydroxyethyl methacrylate (HEMA), which are dissolved in a water solvent and have different degrees of polymerization, are applied to the slurry with a plasticizer (polyethylene glycol). The granules employing a binder with a higher degree of polymerization (PVA) are not broken under a uniaxial press; consequently, they exhibit a poor green density of $2.4g/cm^3$. In contrast, the granule powder compacts employing a binder with a lower degree of polymerization (HEMA) show a higher density of $2.6g/cm^3$ with an increase in plasticizer content. The packing behavior of the granule powders for each organic polymer system is studied by examining the microstructure of the fracture surface at different applied pressures.

• Journal of Sensor Science and Technology
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• v.22 no.6
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• pp.400-403
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• 2013

The piezoelectric composite film of ferroelectric PZT ceramic ($PbZr_xTi_{1-x}O_3$) and polymer (PDMS, Polydimethylsiloxane) was prepared to improve the flexibility of piezoelectric material. The bar coating method was applied to fabricate flexible nanocomposite film with large surface area by low cost process. In the case of using metal electrode on the composite film, although there is no problem by bending process, the electrode is usually broken away from the film by stretching process. However, the well-attached, flexible CNT electrode on PZT/PDMS film improved flexibility, especially stretchability. PZT particles was usually settled down into polymer matrix due to gravity of the weighty particle, so to improve the dispersion of PZT powder in polymer matrix, small amount of additives (CNT powder, Carbon nanotube powder) was physically mixed with the matrix. By stretching the film, an output voltage of PZT(70 wt%)/PDMS with CNT (0.5 wt%) was measured.

• Polymer(Korea)
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• v.28 no.5
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• pp.374-381
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• 2004

Gas permeability of low density polyethylene (LDPE) film containing zeolite powder for $CO_2,\;O_2$ and $N_2$ were investigated. Zeolite powders modified by cations or surfactant were compounded with LDPE to produce $20 wt\%$ masterbatch. After blending the masterbatch with LDPE, zeolite filled films were prepared by the blown film process. Finally, the composite films containing zeolite loadings of 0, 3,5, and $10 wt\%$ were produced. A gas permeability apparatus based on the variable volume principle was designed to analyze the characteristics of films. Experiments showed a general trend that gas permeabilities first decreased and then increased as the zeolite content was increased. Surfactant modified zeolite showed a better interfacial adhesion with the matrix, but the film did not show a discernible difference in gas permeability compared with the other modified films. The difference of temperature dependences in the gas permeabilities of composite films was slightly smaller than that of LDPE film.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.149-152
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• 2002

This study is performed to evaluate the properties of ECO-permeable polymer concrete with blast furnace slag powder and stone dust. The unit weight is in the range of $1,821kg/m^3{\sim}1,955kg/m^3$, the unit weights of those concrete are decreased $15%{\sim}20.8%$ than that of the normal cement concrete. The highest strength is achieved by ECO-permeable polymer concrete filled blast furnace slag powder 50% and stone dust 50%, it is increased 36% by compressive strength, 119% by tensile strength and 217% by bending strength than that of the normal cement concrete, respectively. The coefficient of permeability is in the range of $5.6{\times}10^{-2}cm/s{\sim}8.1{\times}10^{-2}cm/s$, and it is largely dependent upon the mix design.

• Journal of Powder Materials
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• v.6 no.4
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• pp.320-324
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• 1999

The formation, microstructure and properties of novel ceramic composite materials manufactured by active-filler-controlled polymer pyrolysis were investigated. In the presence of active filler particles such as transition metals, bulk components of various geometry could be fabricated from siliconorganic polymer. Molybdenum- and tungsten-filled polymer suspensions were prepared and their conversion to ceramic composites by annealing in $CH_4$ atmosphere were studied. Dimensional change. porosity and phase distribution (filler network) were analyzed and correlated to the resulting hardness values. Molybdenum and tungsten as active filler were carburized completely to $Mo_2C$, $W_2C$ and WC in $CH_4$ atmosphere. Consequently, microcrystalline composites with the filler reaction products embedded in a silicon oxycarbide glass matrix were formed. Hardness was increased with increasing carburization and reached 8.6-9.5 GPa in the specimen pyrolyzed in $CH_4$ atmosphere.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.350-355
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• 1998

Dysprosium monotitanate $(Dy_2TiO_5)$ powder was synthesized by a simple mixed-oxide ceramics process using ethylene glycol (EG). Ethylene glycol, as the organic carrier for the metal cations, was used for polymerization mechanism. The successful used of a non-chelating polymer for the mixed-oxide ceramic process indicated that cation chelation is not the only route for creating stable ceramic precursors. Characterization of the powders by various thermal analysis, microscopy, and diffraction methods has been carried out.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.953-955
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• 2006

In this work we compared different sources of composition of Ag powders obtained by dry and wet process on the photolithographic patterning of PDP electrode and resistance of sintered Ag electrode. It was found that 90 : 10 wt% ratio of Ag powder made by dry and wet processes gave optimum result both on the PDP electrode pattern and resistance of PDP electrode after sintering.

• Macromolecular Research
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• v.10 no.4
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• pp.181-186
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• 2002

The displacement of carbon black to polypyrrole as a catalyst supporter in the fuel electrode of a direct methanol fuel cell was investigated. Polypyrrole was obtained as a black powder by the chemical polymerization of pyrrole with three different oxidants. The synthesized polypyrroles were pasted on carbon paper and transformed to the fuel electrodes with electrochemically deposited platinum. The prepared fuel electrode was assembled and mounted in a unit cell using a membrane and cathodic electrode film. In comparison with the carbon black fuel electrode, the performance of the unit cell was analyzed in relation to the state of the catalyst, the type of oxidant, and the morphology of the polypyrrole powder.