• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1665-1669
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• 2014

Four multialkoxy-functionalized siloxane base-polymers (BP-1~4) were synthesized through either hydrosilylation or condensation reactions in order to prepare multi-networked siloxane polymers having appropriate physical properties for protective coating in fabrications of electronics. Formulations of 4 base-polymers gave coating materials A and B. Product A showed well-controlled flowing and leveling properties, and product A-2 was successfully applied to protective insulating coating for junction areas of connectors and chips in PDP controller. Tack free time, extrusion rate, dielectric breakdown voltage, hardness, thermal stability, water resistance and flame resistance of products A and B were examined.

• Corrosion Science and Technology
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• v.14 no.6
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• pp.280-287
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• 2015

The German Guidelines for stainless steel in buildings (Z.30.3-6) issued by the German Institute for Building Technology (DIBt) categorizevarious stainless steel grades into five corrosion resistance classes (CRCs). Only 21 frequently used grades are approved and assigned to these CRCs. To assign new or less commonly used materials, a large program of outdoor exposure tests and laboratory tests is required. The present paper shows theresults of stress corrosion cracking (SCC) tests that can distinguish between different CRCs. Slow strain rate tests (SSRT) were performedin various media and at different temperatures. CRC IV could be distinguished from CRC II and CRC III with a 31.3 % $Cl^-$ as $MgCl_2$ solutionat $140^{\circ}C$. CRC II and CRC III could be differentiated by testing in a 30% $Cl^-$ as $MgCl_2$ solutionat $100^{\circ}C$.

• Carbon letters
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• v.11 no.2
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• pp.102-106
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• 2010

In this work, the effect of aminized multi-walled carbon nanotubes (NH-MWNTs) on the mechanical interfacial properties of epoxy nanocomposites was investigated by means of fracture toughness, critical stress intensity factor ($K_{IC}$), and impact strength testing, and their morphology was examined by scanning electron microscope (SEM). It was found that the incorporation of amine groups onto MWNTs was confirmed by the FT-IR and Raman spectra. The mechanical interfacial properties of the epoxy nanocomposites were remarkably improved with increasing the NH-MWNT content. It was probably attributed to the strong physical interaction between amine groups of NH-MWNTs and epoxide groups of epoxy resins. The SEM micrographs showed that NH-MWNTs were uniformly embed and bonded with epoxy resins, resulted in the prevention of the deformation and crack propagation in the NH-MWNTs/epoxy nanocomposites.

• Journal of the Korean Ceramic Society
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• v.47 no.1
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• pp.39-46
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• 2010

The kinetics of cation reequilibration have been studied theoretically and experimentally in complex oxides after an external perturbation of equilibrium by temperature jumps. A general kinetic model for cation redistribution amongst non-equivalent sites in complex oxides is derived based on a local homogeneous point defect mechanism involving cation vacancies. Temperature-jump optical relaxation spectroscopy has been established to investigate cation kinetic processes in spinels and olivines. The kinetic model satisfactorily describes the experimental absorbance relaxation kinetics in cobalt containing olivines and in nickel containing spinels. It is found that the kinetics of cation redistribution in complex oxides shows a strong temperature- and composition-dependence. Activation energies for cation redistribution in Co-Mg olivines are found to range between 200 and 220 kJ/mol whereas an energy barrier of about 230 kJ/mol is observed in the case of nickel gallate spinel.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.775-775
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• 2006

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.590-594
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• 2013

Semiconductor CdSe nanowires (NWs) can serve as model systems for investigating the physical properties of one-dimensional (1D) nanostructures and have great potential for applications in electronics and photonic nanodevices. With numerous attractions arisen from their physical properties, CdSe NWs have been synthesized by vapor-liquid-solid (VLS) methods, but they have some limitations of high reaction temperature and low production. Here, we synthesized CdSe NWs via the solution-liquid-solid (SLS) mechanisms using bismuth (Bi) covered substrates as a low-melting point catalyst and compared the products after injecting identical amount of Se and different amount of tributylphosphine (TBP). CdSe NWs have similar diameters but longer lengths with decreasing TBP, so we proposed the role of TBP as a solvent and capping agent of Se.

• Elastomers and Composites
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• v.30 no.1
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• pp.9-19
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• 1995

To make filler loaded conducting rubber which has the excellent electronical and physical properties, CR and NBR were mixed with magnetite$(Fe_3O_4)$. From the result of the study, vulcanization characteristics shows the upgrading curve as increase in filler concentration and CR has more torque than NBR. When elongation be higher, modulus comes to decreases. Tear strength gradually decrease after showing of the maximum point when is in the 100phr in all. Resilience is not good to cause the increase in filler concentration. In the electrical properties, conductivity becomes smaller when filler concentration is increased. The increase of voltage makes an conductivity grown, but the changed rate is weak. The influence of temperature hardly changes on increasing temperature. The morphology and the distribution for a conductivity filler through SEM were better, the more filler concentration increase, the shorter the particle interval is.

• Transactions on Electrical and Electronic Materials
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• v.13 no.1
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• pp.2-5
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• 2012

We have designed, synthesized, and evaluated the physical properties of some high birefringence (${\Delta}n$) isothiocyanato biphenyl-bistolane liquid crystals. These compounds exhibit ${\Delta}n^-$ 0.4-0.7 at room temperature and wavelength $\lambda$=633 nm. Laterally substituted short alkyl chains and fluorine atom eliminate smectic phase and lower the melting temperature. The moderate melting temperature and very high clearing temperature make those compounds attractive for eutectic mixture formulation. Several mixtures based on those compounds were formulated and its physical properties evaluated.

• Bulletin of the Korean Chemical Society
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• v.15 no.1
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• pp.64-74
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• 1994

The nonstoichiometric chalcogenides with NaCl-type structure were prepared and the physical and structural properties were studied. The homogeneous range and the structural change were studied based on X-ray powder diffractions using Rietveld-type full-profile fitting technique. Wide homogeneous ranges were observed in Y-S and Y-Se systems, and relatively narrow homogeneous ranges were observed in Yb-S and Yb-Se systems. Both in $Yb_{1-x}S\;and\;Yb_{1-x}Se$, a vacancy ordering transition occurred in (111) plane direction. The ordered superstructure had cubic symmetry(Fm$\bar{3}m) with doubled unit cell "a" parameter compared to the original NaCl-type. The superlattice developed in a continuous second-order transitiion was characterized by the reduced waved vector k= $(a^*+b^*+c^*)/2$. Y-S system had metallic, and YSe, YbSe system had semiconducting properties in their homogeneous ranges. It was observed that the change of electronic transport properties in extended homogeneous range did not depend on the relativeratio of metal to nonmetal, but on the quantities of vacancies.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.79-86
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• 2018

Although the intrinsic characteristics of DNA molecules and carbon nanotubes (CNT) are well known, fabrication methods and physical characteristics of CNT-embedded DNA thin films are rarely investigated. We report the construction and characterization of carboxyl (-COOH) group-modified multi-walled carbon nanotube (MWCNT-COOH)-embedded DNA and cetyltrimethyl-ammonium chloride-modified DNA (DNA-CTMA) composite thin films. Here, we examine the structural, compositional, chemical, spectroscopic, and electrical characteristics of DNA and DNA-CTMA thin films consisting of various concentrations of MWCNT-COOH. The MWCNT-COOH-embedded DNA and DNA-CTMA composite thin films may offer a platform for developing novel optoelectronics, energy harvesting, and sensing applications in physical, chemical, and biological sciences.