• Macromolecular Research
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• v.13 no.3
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• pp.243-252
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• 2005

The effect of the vinyl acetate (VA) content on the thermal, viscoelastic, rheological, morphological and mechanical behaviors in various blends of ethylene-vinyl acetate (EVA)/ethylene-$\alpha$-olefin copolymers was investigated using 28, 22 and $15 mol\%$ of VA in EVA. In the DSC melting and crystallization thermograms of all of the EVA systems blended with ethylene-$\alpha$-olefin copolymers, discrete peaks were observed which were related to the constituents. In the dynamic mechanical thermal analysis, the storage modulus increased with increasing content of ethylene-$\alpha$-olefin copolymers. In addition, the transition regions relating to the tan bpeaks varied with the VA content. The crossover point between G' and G" varied depending on the VA contents, and shear-thinning was more prominent in the EVA/EtBC system. In the SEM investigation, a discrete phase morphology was observed in both the EVA/EtBC and EVA/EtOC blends, but the contrast improved with decreasing VA content. However, the tensile strength and modulus improved, but the elongation at break reduced with decreasing VA content, implying that the ethylene-$\alpha$-olefin copolymers play the role of reinforcing materials. Thus, the EVA and ethylene-$\alpha$-olefin components in the copolymers are immiscible in the molten and solid states, but are nevertheless mechanically compatible.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1199-1203
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• 2012

Catalytic filters consisting of Ni nanoparticle and carbon fiber with different oxidation states of Ni (either metallic or oxidic) were prepared using a chemical vapor deposition process and various post-annealing steps. CO oxidation reactivity of each sample was evaluated using a batch type quartz reactor with a gas mixture of CO (500 mtorr) and $O_2$ (3 torr) at $300^{\circ}C$. Metallic and oxidic Ni showed almost the same CO oxidation reactivity. Moreover, the CO oxidation reactivity of metallic sample remained unchanged in the subsequently performed second reaction experiment. We suggested that metallic Ni transformed into oxidic state at the initial stage of the exposure to the reactant gas mixture, and Ni-oxide was catalytically active species. In addition, we found that CO oxidation reactivity of Ni-oxide surface was enhanced by increase in the $H_2O$ impurity in the reactor.

• Macromolecular Research
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• v.10 no.6
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• pp.325-331
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• 2002

Phase behavior of a PEO-PPO-PEO (Pluronic P103) triblock copolymer in water is investigated using small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), dynamic light scattering (DLS) and rheology. Pluronic P103 shows apparent two gel states in different temperature regions. The first sol-to-gel transition at a lower temperature (i.e., the hard gel I state) turns out to be the hexagonal microphase as evidenced by the combined SANS and SAXS and the frequency dependence of both G′ and G" in rheology. In contrast to the hard gel I, the second sol-to-gel transition (i. e., the hard gel II state) at a higher temperature represents the block copolymer micelles in somewhat disordered state rather than the ordered state seen in the hard gel I. Moreover, turbidity change depending only on the temperature with four distinct regions is observed and the large aggregates with size larger than 5,000 nm are detected with DLS in the turbid solution region. Based upon the present study, two different gelation mechanisms for aqueous PEO-PPO-PEO triblock copolymer solutions are proposed.

• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.90-98
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• 1998

In order to establish detailed plans for fire protection and reduce the possible fire accidents in the future, collection of domestic and foreign fire accident cases and fundamental analysis are very important. In this study the classification model for fire accidents was developed and the direction to a new model was suggested by comparison ours with the accidents classification model of NFPA of United States of America and Japan. A new developed PC-based database program for fire accidents (FADBS) was used to analyse fire accidents easily and efficiently.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.05a
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• pp.10-14
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• 2001

Physical chemistry states that electric potential is due to Gibb's free energy from chemical reaction of the electric cell. However we have not the electromagnetic meaning of Gibb's free energy. the free energy is discovered to be a kinetic energy part of the rotating electromagnetic wave ($\pi$-ray), which is different from conventional Coulomb attraction energy and can anticipate that there is a current difference between before and after the electric load. This paper manipulates the relationship between $\pi$-rays (Gibb's free energy) and electrolysis, cell reaction and brown gas reaction.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.656-660
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• 2000

In general, the silo blender is composed of silo, blending cone and vane. This study is to develop the blending system for resin of industrial materials produced in the chemical plant By examining closely the How states at the six flow zones of different geometry in the blender due to the gravity of resin, it is possible to develop the silo blender by the optimum design through the sin and the capacity change.

• YAKHAK HOEJI
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• v.16 no.2
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• pp.108-112
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• 1972

S-Trifluoroacetoxy-trihalomethyl mercaptans were prepared by reacting metal salt of trihaloacetic acid with perhalomethyl mercaptans in the closed vessel. And besides, certain decomposed states of these products by heat and U.V. were studied by Infra red, N.M.R., molecular weight determination and chemical analysis methods. The results showed that the more fluorine substituted compounds were more stable than the less fluorine substituted ones.

• Proceedings of the Korean Vacuum Society Conference
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• 2006.08a
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• pp.166-166
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• 2006

• Journal of Photoscience
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• v.12 no.1
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• pp.47-50
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• 2005

Mediumeffects have been explored on the competitive H-atom abstraction and SET-promoted, silyl-transfer reactions of excited states of silylalkyl-substituted phenyl ketones. The chemical selectivities of photochemical reactions of silylalkyl phenyl ketones appear to depend on medium polarity, medium silophilicity, added metal cation and alkyl length. Irradiations of silylalkylketones in aqueous solvent system and in presence of metal cation such as $Li^+$ and $Mg^{+2} $lead to formation of acetophenone predominantly by the sequential SET-silyl transfer route.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.228-229
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• 2000

Magnetic Fe nanoparticles were synthesized by CVC process using Fe(CO)$\sub$5/ as precursors. The nanoparticles have core-shell structures with uniform dispersion. For the specific purposes, the micostructures as well as the magnetic states of Fe nanoparticles can be controlled by adjusting the process parameters, such as the carrier gases, the decomposition temperature, the cooling of powder, etc.