• Fibers and Polymers
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• 제7권1호
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• pp.36-41
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• 2006

PVC and SAN are often mixed to compensate for the disadvantages of each polymer. Miscibility and thermal stability of PVC/SAN blend were investigated in this study by blending SAN polymer having 20, 24, 28, 32 % of acrylonitrile contents. Two polymers were mixed using a melt blending method with a single screw extruder. DSC thermogram was used to evaluate miscibility of the two polymers. SAN having 24 % of acrylonitrile showed the best miscibility with PVC. In order to evaluate degradation behavior, blended polymer was heat treated in DSC furnace and glass transition temperature was measured consecutively. Glass transition temperature increased continuously with annealing time due to degradation and cross-linking of polymer chains. Melt index of blended polymer was always higher than that of PVC.

• 대한금속재료학회지
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• 제46권2호
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• pp.65-68
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• 2008

Generally CCM (cold crucible melting) is not suitable for melting glass. However, in this study we described the quantitative relationship between the basic property of glass and power balance, the power absorption in the melt, the losses in the coil and the cold crucible, for melting glass in CCM. The dependence of power balance on the applied frequency and the electric conductivity has been found. Above 300 kHz, the glass (B) contained alkali ion which has the low resistance $3.0{\Omega}{\cdot}cm$ at $900^{\circ}C$ and $1.36{\Omega}{\cdot}cm$ at $1,100^{\circ}C$ was melted easily and 60% of the overall power was absorbed in the melt and 30% and 10% of the overall power was lost in the cold crucible and coil respectively. Under the same condition, the glass (A) contained non-alkali ion was not melted easily and 50% of the overall power was absorbed in the melt and 40% and 10% of the overall power was lost in the cold crucible and coil respectively. In conclusion, the small absorbed power of the overall power in melt prevented a successful melting as for glass A, and the successful melting depends on the relative size of the absorbed power in melt irrespective of the melting volume. Hence, as typical for direct induction heating method(CCM), the successful melting strongly depended on the chosen working frequency based on electric conductivity of glass, power balance and the control of the critical power which was absorbed in melt.

• 한국세라믹학회지
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• 제52권2호
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• pp.83-91
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• 2015

The redox reaction $M^{(x+n)+}+\frac{n}{2}O^{-2}{\rightleftarrows}M^{x+}+\frac{n}{4}O_2$ of multivalent ions in glass melts influences the melting process and final properties of the glass including the fining (removal of bubbles), infrared absorption and homogenization of melts, reaction between metal electrodes and melts or refractory and melts, and transmission and color of glass. In this review paper, the redox behaviors that occur frequently in the glass production process are introduced and the square wave voltammetry (SWV) is described in detail as an in situ method of examining the redox behavior of multivalent ions in the melt state. Finally, some voltammetry results for LCD glass melts are reviewed from the practical viewpoint of SWV.

• 한국세라믹학회지
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• 제34권7호
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• pp.781-789
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• 1997

Pressure sintered SiC specimens were joined using MgO-Al2O3-SiO2 (MAS) glass which has a thermal expansion coefficient similar to that of SiC. MAS melt showed excellent behavior of wetting on the SiC substrate over 148$0^{\circ}C$, and the wettability was much influenced by the joining atmosphere. The joining was conducted at 150$0^{\circ}C$ for 30 min in Ar atmosphere. The flexural strength of the joined specimen shows 342~380 MPa up to 80$0^{\circ}C$, which is almost the same as that of as-recieved SiC specimen. However, the flexural strength of the joined specimen decreased to about 80 MPa at 90$0^{\circ}C$ due to softening of the glass melt. The analyses od XRD and WDS show that the reaction between the SiC specimen and the MAS melt produces the oxycarbide glass, which had a high strength and a good stability at high temperatures.

• 한국세라믹학회지
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• 제52권2호
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• pp.137-139
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• 2015

In this study, we examined the influence of molten $KNO_3$ flow on mechanical properties and their deviation when a chemical toughening process was applied to soda lime silicate glass ($Na_2O-CaO-SiO_2$). $KNO_3$ melt flow was controlled using three methods: (1) glass tray rotation, (2) impeller stirring, and (3) natural convection. DOL and hardness were found to be enhanced by tray rotation because this rotation was able to maintain the concentration around the glass surface, in contrast to other methods. However, there did not appear to be a statistically significant difference in the 3-point bending strength for the three flow conditions due to the ground edge condition.

• 보존과학연구
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• 통권21호
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• pp.57-75
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• 2000

We performed the scientific analysis through composition analysis, micro-structure investigation, melting point and hardness test to the glass beads excavated at Naesanri in Gosung. Through this investigation, we could examine closely the characterization of raw materials and manufacture technique As a result of micro-structure investigation of glass beads, it appeared that the bubbles in glass beads have remained. Coloring agents of yellow glass bead was remained to the shape of inclusion. And on observing the transparent solid particle, we can know that these do not melt the raw materials because of low melting temperature of a crucible. The result of composition analysis of all glass beads using ICP, these were classified as $Na_2O_2$-$SiO_2$ type of glass. Also, these added to $AI_2O_3$ to improve the durability. The value of Vickers hardness of glass beads appeared the HV 490-530. The HV 1,440 of the transparent solid particle was much more than that of inner glass bead. This means that raw materials do not melt because of a low melting temperature of a crucible. The result of melting temperature analysis of glass beads using DSC/TGA, it was measured about $1,250^{\circ}C$.

• 한국세라믹학회지
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• 제41권4호
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• pp.344-347
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• 2004

The influence of spindle immersion depth on the determination of glass melt viscosity was examined in rotating cylinder method. The exact adjustment of spindle immersion depth into soda lime silicate standard glass melts could be peformed by self-constructed electric system. The results showed a slight dependence of viscosity value on the immersion depth change of spindle shaft. The viscosity error per unit length of spindle was 0.4%/mm under the present cylinder dimension.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 춘계학술논문요약집
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• pp.214-215
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• 2018

• 한국세라믹학회지
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• 제45권2호
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• pp.90-93
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• 2008

The oxygen gas behavior in PDP (plasma Display Panel) glass melts doped with sulfate ($SO_4^{-2}$) or blast furnace slag (BFS, $S^{2-}$) or both by means of yttria-stabilized zirconia (YSZ) electrodes was observed after the first fining. The temperature dependence of oxygen equilibrium pressure ($P_{O2}$) in each melt showed typical behavior, namely $P_{O2}$ decreased as temperature decreased. This suggests that an oxidation of $S^{4+}$ to $S^{6+}$ took place. However, the $P_{O2}$-value at constant temperature increased in the following order: BFS$P_{O2}$ of the melt doped with sulfate+BFS was much lower than that of the melt with only sulfate, although only 10% of sulfur was added by the BFS. This behavior can be explained by the redox reaction between sulfide ions in the BFS and dissolved oxygen ions in the melt during the first fining.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1025-1029
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• 2003

We studied the cross-sectional profiles of deformed thermoplastics in hot embossing process and compared with melt flow index for various embossing conditions such as embossing temperature, embossing pressure and initial thickness of the thermoplastics. The fastest embossing times for complete penetration of the cavities were obtained at temperature greater than $60^{\circ}C$ above glass transition temperature (Tg). When the melt flow index of polymer is low, the penetration ratio does not become large even if the embossing pressure increases. The complete occupation of the cavities was easier obtained with high melt flow index polymer than low melt flow index polymer at the same process condition. We believe these results can be very useful for optimizing nanostructured hot embossing also known nanoimprinting process conditions.