• Polymer(Korea)
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• v.32 no.6
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• pp.523-528
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• 2008

Diglycidyl ether of bisphenol-A (DGEBA) was selected as a compatibilizer in Nylon 6 and bisphenol-A polycarbonate (PC) blends. SEM revealed a much finer morphology in the presence of DGEBA. The thermal properties, such as glass transition, melting point, crystallization temperature and rate, of the blends were examined using DSC. Overall, the introduction of DGEBA caused a strong dependence of these thermal properties on the composition due to compatibilization.

• Journal of Korean Vacuum Science & Technology
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• v.3 no.1
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• pp.54-58
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• 1999

We deposited diamond-like carbon (DLC) films using ion beam sputtering of a graphite target on flat substrates for use as a thin film field emitter. An n-type silicon wafer, titanium-coated silicon, and indium tin oxide (ITO) coated glass were used as a substrate. All films exhibited a sudden increase in the emission after a breakdown occurred at high voltage. The morphology of the films after the breakdown depended on the substrate. On ITO and Ti substrates, the DLC film peeled off upon breakdown, but on the Si substrate the surface melting due to breakdown resulted in the formation of various structures such as a sharp point, mound, and crater. By scanning the deformed surface with a tip anode, we found that the emission was concentrated at the deformed sites, indicating that the field enhancement due to the morphology change was responsible for the increased emission.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.1
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• pp.1-9
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• 2013

The rare earth oxide wastes consisting of major 8 nuclides Y, La, Ce, Pr, Nd, Sm, Eu and Gd, are generated during the salt waste treatment of PyroGreen process. The final form of the rare earth is generated as the oxide state. In this study, six candidate glasses were developed to evaluate the feasibility for vitrifying the rare earth oxide wastes within the borosilicate glass system. The solubilities of the mixture of the rare earth oxide waste showed less than 25wt% at $1,200^{\circ}C$, less than 30wt% at $1,300^{\circ}C$, respectively. It means that solubility is increased with the temperature increment. The liquidus temperature of the homogeneous glass with 20wt% waste loading was determined as less than $950^{\circ}C$. In more than solubility of rare earth oxides glass, formation of rare earth-oxide-silicate crystal in glass-ceramic occurred as the secondary phase. As their viscosity at melting temperature $1,200{\sim}1,300^{\circ}C$ was less than 100 poise, electrical conductivity was higher than 1 S/cm, 20~25wt% waste loading glasses with good surface homogeneity are judged to have good operability in cold crucible induction melter. Other physicochemical properties of the developed glasses are going to be experimented in the future.

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.721-727
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• 2002

In order to overcome trade-off among compositions, process and properties of the glasses with high PbO-base composition for PDP Rib, we studied glass crystallization and crystallization kinetics by Differential Thermal Analysis(DTA). Glass powder was obtained through melting/cooling/grinding, with 3 wt%TiO2 addition for the crystal nucleation and growth in $62PbO-19B_2O_3-10SiO_2-9(Al_2O_3-K_2O-BaO-ZnO)$(in wt%) composition glass. This powder was heat-treated for 1 to 10 h at $445^{\circ}C$ for nucleation. DTA measurements were performed to obtain the crystallization peak with $5∼25^{\circ}C/min$ heating rates. DTA crystallization peak temperature increased with increasing the heating rate and decreased with increasing the heating time. Because the Avrami parameter (n) was approximately 1, the surface crystallization occurred. The maximum nucleation time was 2 h.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2003.05a
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• pp.66-66
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• 2003

King George island, Antarctica, is mostly covered by ice sheet and glaciers, but the land area is focally exposed for several thousand years after deglaciation. For a mineralogical study of chemical weathering in the polar environment, glacial debris was sampled at the well-developed patterned ground which was formed by long periglaclal process. As fresh equivalents, recently exposed tills were sampled at the base of ice cliff of outlet glaciers and at the melting margin of ice cap together with fresh bedrock samples. Fresh tills are mostly composed of quartz, plagioclase, chlorite, and illite, but those derived from hydrothermal alteration zone contain smectite and illite-smectite. In bedrocks, chlorite was the major clay minerals in most samples with minor illite near hydrothermal alteration zone and interstratified chlorite-smectite in some samples. Smectite closely associated with eolian volcanic glass was assigned to alteration in their source region. Blocks with rough surface due to chemical disintegration showed weathering rinds of several millimeter thick. Comparision between inner fresh and outer altered zones did not show notable change in clay mineralogy except dissolution of calcite and some plagioclase. Most significant weathering was observed in the biotite flakes, eolian volcanic glass, sulfides, and carbonates in the debris. Biotite flakes derived from granodiorite were altered to hydrobiotite and vermiculite of yellow brown color. Minor epitactic kaolinite and gibbsite were formed in the cleaved flakes of weathered biotite. Pyrite was replaced by iron oxides. Calcite was congruently dissolved. Volcanic glass of basaltic andesite composition showed alteration rim of several micrometer thick or completely dissolved leaving mesh of plagioclase laths. In the alteration rim, Si, Na, Mg, and Ca were depleted, whereas Al, Ti, and Fe were relatively enriched. Mineralization of lichen and moss debris is of much interest. They are rich of A3 and Si roughly in the ratio of 2:1 to 3:1 typical of allophane. In some case, Fe and Ti are enriched in addition to Al and Si. Transmission electron microscopy of the samples rich of volcanic glass showed abundant amorphous aluminosilicates, which are interpreted as allophane. Chemical weathering in the King George Island is dominated by the leaching of primary phyllosilicates, carbonates, eolian volcanic glass, and minor sulfides. Authigenesls of clay minerals is less active. Absence of a positive evidence of significant authigenic smectite formation suggests that its contribution to the clay mineralogy of marine sediments are doubtful even near the maritime Antarctica undergoing a more rapid and intenser chemical weathering under more humid and milder climate.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.5
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• pp.249-254
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• 2016

In this study, we investigated the main characteristics of off-gas generated from melting process and off-gas treatment system operation example to provide some primary data for commercial vitrification facility design. The purpose of vitrification facility operation is to treat hazardous materials in the radioactive wastes and harmful off-gas containing a variety of chemical species generated in the glass melting process. Constructing and operating vitrification facility essentially need to be licensed through safety analysis; it is very important to treat radionuclide and hazardous materials below the legal environment emissions regulation level. We must accurately understand the characteristics of off-gas and apply an appropriate off-gas treatment process accordingly. Thus, to design the appropriate off-gas treatment there must be a wide range of elements taken into account such as characteristics of waste and melter, regulation guidance of off-gas, characteristics of generated off-gas and off-gas treatment system performance assessment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1546-1552
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• 2016

In addition, because it uses preheating to dissolve an alloy in general, it is hard to regulate the appropriate melting temperature of the alloy and brewing time and shows the defect of the supplementation thing due to the super-heating. Once the alloy is molten and then most of the casting by attaching a sight glass or non-contact temperature sensor is suitable casting temperature the operator pressing a button to generate a centrifugal force to inject the molten alloy into a crucible in the casting ring. These results, and most of the cast temperature is too high or too low to generate a lot of casting defects do not get into a uniform cast body. In this paper, we developed a dental casting machine for high frequency using a single temperature sensor which can measure the actual temperature of the alloy than the temperature of the external non-contact measurement using a temperature sensor.

• Polymer(Korea)
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• v.24 no.1
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• pp.48-57
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• 2000

Polycaprolactone (PCL) and thermoplastic starch (TPS) blends were prepared. Mechanical properties, thermal property, water absorption, biodegradability by composting and surface morphology of PCL/TPS blends were investigated. The compositions of PCL/TPS blends were 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, and 10/90. Strength and elongation at break decreased as the content of TPS increased, while modulus increased. DSC thermogram of TPS showed two glass transition temperatures (T$_{g}$ ) at 23$^{\circ}C$ and 126$^{\circ}C$. And TPS proved to be an amorphous polymer because there was no endothermic peak due to the melting of starch crystal. The unchanged melting temperatures and T$_{g}$ 's of PCL/TPS blends revealed that PCL and TPS were not miscible. All of the blends were found to be mechanically compatible but phase separated in each other. After 45 days composting, the biodegradability of PCL was 44% and that of PCL/TPS blends increased as the contents of TPS increased.

• Polymer(Korea)
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• v.37 no.1
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• pp.74-79
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• 2013

Polyvinylidene fluoride (PVDF) and its copolymer with hexafluoropropylene (HFP) were successfully prepared from free radical solution polymerizations using diisopropyl peroxidicarbonate (DIPPDC) in the presence of 1,1,2-trichlorotrifluoroethane (R-113). The reactivity ratios of VDF and HFP were estimated as$r_{VDF}=2.06{\pm}0.03$ and $r_{HFP}{\approx}0$. This result indicates that HFP cannot undergo self propagation. The weight-average molecular weight and molecular weight distribution of copolymers were found to decrease with increasing HFP content. The melting temperature of copolymers linearly decreased with the increase of HFP content because of the introduction of HFP. Moreover, no melting peak was observed for the copolymers with high HFP content. The glass transition temperature of copolymers gradually increased with the increase of HFP content due to the restricted flexibility of the polymer chains.

• Resources Recycling
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• v.5 no.1
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• pp.3-8
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• 1996

CZS(2Ca0 , SiO\ulcorner) phase of cement clinkcr was obtaincd by melting mixcd four indnstrial wasles of limestone sludge, waste Foundry sand, coal lly ash fiorn power plants and chernicas glasses. The effect ot mixing ratio of four rvastc mater~als ou the composnlg phascs in melled slag was investigated. Thc mixed wastes were meltcd to slag by heat under a constant basicity at 1370C. The shg consisted of p -CIS and C,AS(2CaO - A I P , . SiO,). The ratio of two phases was varied with mixing ~atioo f the waste materials. In order Lo increasc the amount ot j -C2S phase, the coal fly ash content should be reduced, while amount of the chemical glass be increased. The coal fly ash contcnt was the most imporlant factor in controlling phases of thc melted-slag.