• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.3
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• pp.499-503
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• 2016

For safety and economy reasons, hazardous waste including radioactive waste is desired to be converted into stable waste forms with a maximum volume reduction. High temperature melting technology using a plasma torch system can effectively treat even the non-flammable waste as desired. By far, one of the most difficult process for melting the non-flammable waste is a tapping of melts because the melting point of a residual slag in the tapping hole is high and because the viscosity of the melt increases sharply when tapping out. In case of a stationary furnace with a slant tapping port on the side of furnace, a certain amount of melts is left in the tapping hole after tapping out. Because of this, at every end of a melting cycle, the tapping hole needs to be opened by tapping device. The developed tapping device of melts based on both a guide electrode and auxiliary electrode is adequate for the application to discharge of melts except that the consumption of the guide electrode is somewhat faster than expected. Melt is collected in the water cooled vessel.

• Journal of the Mineralogical Society of Korea
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• v.18 no.1
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• pp.45-52
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• 2005

The recent development and advances in 2 dimensional solid-state NMR, particularly, triple quantum (3Q) MAS NMR yield much improved resolution compared with conventional 1 dimensional MAS NMR, allowing us to study the distributions of cations and anions in the non-crystalline silicate glasses and melts. Here, we present the recent progress made by 3QMAS NMR spectra of silicate glasses quenched from melts at pressures up to 10 GPa in a multi-anvil apparatus, revealing previously unknown details of structures of covalent oxide glasses and melts at high pressure.

• Korean Journal of Metals and Materials
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• v.50 no.2
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• pp.116-121
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• 2012

Equilibria between Mn-Si melts and $MnO-SiO_2$ slags were studied at 1673 K and 1773 K in MnO crucibles to accurately determine the thermodynamic property of the Mn-Si melts. The Unified Interaction Parameter Formalism (UIPF) was used to describe the thermodynamic property of the Mn-Si liquid. Using the UIPF, the experimental results obtained in the present study were thermodynamically analyzed to determine the activity coefficient of Si at infinite dilution and the 1st- and 2nd-order self-interaction parameters of Si in the Mn-Si melts.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.3
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• pp.121-126
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• 2006

HVOF thermal spray coating of Co-alloy T800 is progressively replacing the classical hard coatings such as chrome plating because of the very toxic $Cr^{6+}$ ion known as carcinogen causing lung cancer. For the study of the possibility of replacing of chrome plating, the wear properties of HVOF Co-alloy T800 coatings are investigated using the reciprocating sliding tester both at room and at an elevated temperature of $1000^{\circ}F\;(538^{\circ}C)$. The possibility as durability improvement coating is studied for the application to the high speed spindles vulnerable to frictional heat and wear. Wear mechanisms at the reciprocating sliding wear test are studied for the application to the systems similar to the sliding test such as high speed spindles. Wear debris and frictional coefficients of T800 coatings both at room and at an elevated temperature of $1000^{\circ}F\;(538^{\circ}C)$ are drastically reduced compared to those of non-coated surface of parent substrate Inconel 718. This study shows that the coating is recommendable for the durability improvement coatings on the surfaces vulnerable to frictional heat. The sliding surfaces are weared by the mixed mechanisms such as oxidative wear, abrasion by the sliding ball slurry erosion by the mixture of solid particles and small drops of the melts and semi-melts of the attrited particles cavitation by the relative motions among the coating, sliding ball, the melts and semi-melts. and corrosive wear. The oxide particles and the melts and semi-melts play roles as solid and liquid lubricant reducing the wear and friction coefficient.

• Korea-Australia Rheology Journal
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• v.17 no.3
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• pp.111-116
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• 2005

The new tube model with variable diameter (Marrucci and Ianniruberto, 2004), recently introduced to interpret new elongational data of polymer melts, is here extended to encompass arbitrary flows, specifically shear flows. The predicted results compare well with existing data of entangled polymer melts. Challenges still remain when the comparison is extended to recent elongational data on entangled solutions by Sridhar.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.148-152
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• 2008

A series of lithium chloride-imidazolium chloride (LiCl-[imidazolium]Cl) melts were prepared and their catalytic activities were evaluated for the coupling reactions of propylene oxide and CO2. At the constant mole of LiCl, the catalytic activities of LiCl-[imidazolium]Cl melts increased with increasing molar ratio of [imidazolium]Cl/LiCl up to 2, but thereafter decreased rapidly. The variation of alkyl groups on the imidazolium ring showed a negligible effect on the catalytic activity, but the number of alkyl groups present on the imidazolium cation exerts a pronounced effect. Catalysis and electrospray ionization tandem mass spectral analysis results of LiCl-[imidazolium]Cl melts imply that the activity of the melt is strongly related to the amount of LiCl2- generated from the melt.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3771-3776
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• 2013

1-Alkyl-3-methylimidazolium chloride-LiCl melts were prepared from the reaction of 1-alkyl-3-methylimidazolium chloride ([RMIm]Cl; R=allyl or n-butyl) and lithium chloride, and their ability to dissolve cellulose was evaluated. The solubility of cellulose was greatly increased to 320% when [RMIm]Cl was replaced by [RMIm][$LiCl_2$]. Dissolved cellulose in LiCl/[RMIm]Cl melts was successfully regenerated by adding water and LiCl/[RMIm]Cl melts were easily recovered by removing water. As supported by the computational results, the higher solubility of cellulose in [RMIm][$LiCl_2$] can be ascribed to the increased bond distance between anion and C(2)-H of the imidazolium ring compared with that in [RMIm]Cl, thereby resulting in the increased interaction between $[LiCl_2]^-$ and the hydroxyl groups of cellulose.

• Korea-Australia Rheology Journal
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• v.18 no.4
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• pp.199-207
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• 2006

Measurements by Luap et al. (2005) of elongational viscosity and birefringence of two nearly monodisperse polystyrene melts with molar masses $M_{w}$ of $206,000g{\cdot}mol^{-1}$ (PS206k) and $465,000g{\cdot}mol^{-1}$ (PS465k) respectively are reconsidered. At higher elongational stresses, the samples showed clearly deviations from the stress optical rule (SOR). The elongational viscosity data of both melts can be modeled quantitatively by the MSF model of Wagner et al. (2005), which is based on the assumption of a strain-dependent tube diameter and the interchain pressure term of Marrucci and Ianniruberto (2004). The only nonlinear parameter of the model, the tube diameter relaxation time, scales with $M_{w}^{2}$. In order to get agreement with the birefringence data, finite chain extensibility effects are taken into account by use of the $Pad\'{e}$ approximation of the inverse Langevin function, and the interchain pressure term is modified accordingly. Due to a selfregulating limitation of chain stretch by the FENE interchain pressure term, the transient elongational viscosity shows a small dependence on finite extensibility only, while the predicted steady-state elongational viscosity is not affected by non-Gaussian effects in agreement with experimental evidence. However, deviations from the SOR are described quantitatively by the MSF model by taking into account finite chain extensibility, and within the experimental window investigated, deviations from the SOR are predicted to be strain rate, temperature, and molar mass independent for the two nearly monodisperse polystyrene melts in good agreement with experimental data.

• Metals and materials international
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• v.24 no.6
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• pp.1386-1393
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• 2018

The solubility of $TiO_2$ in $NaF-CaF_2-BaF_2$ ternary eutectic melts was investigated at the temperature range of $1025-1150^{\circ}C$. The least-squares equation was obtained from the relationship between the reciprocal temperature and the natural logarithm of the titanium concentration in the melts saturated with $TiO_2$. The corresponding partial molar enthalpy of dissolution of $TiO_2$ was found to be 188 kJ/mol. The titanium saturation concentration was 3.73 wt% at $1100^{\circ}C$. From the titanium concentration change with the added amount of $TiO_2$ at different holding time after a final stirring, it was found that not only complete dissolution of $TiO_2$ but also enough sedimentation of excessive $TiO_2$ should be guaranteed to obtain more reliable solubility data. The holding time of 10 h was found to be enough for the excessive $TiO_2$ particles to settle down in our experimental conditions. It is noteworthy that in case of adding $TiO_2$ in excess of its solubility, the $Ba_{1.12}(Ti_8O_{16})$ phase was observed at the lower and bottom of the solidified salt ingots.

• Korea-Australia Rheology Journal
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• v.21 no.4
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• pp.203-211
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• 2009

In flows with deformation rates larger than the inverse Rouse time of the polymer chain, chains are stretched and their confining tubes become increasingly anisotropic. The pressures exerted by a polymer chain on the walls of an anisotropic confinement are anisotropic and limit chain stretch. In the Molecular Stress Function (MSF) model, chain stretch is balanced by an interchain pressure term, which is inverse proportional to the $3^{rd}$ power of the tube diameter and is characterized by a tube diameter relaxation time. We show that the tube diameter relaxation time is equal to 3 times the Rouse time in the limit of small chain stretch. At larger deformations, we argue that chain stretch is balanced by two restoring tensions with weights of 1/3 in the longitudinal direction of the tube (due to a linear spring force) and 2/3 in the lateral direction (due to the nonlinear interchain pressure), both of which are characterized by the Rouse time. This approach is shown to be in quantitative agreement with transient and steady-state elongational viscosity data of two monodisperse polystyrene melts without using any nonlinear parameter, i.e. solely based on the linear-viscoelastic characterization of the melts. The same approach is extended to model experimental data of four styrene-butadiene random copolymer melts in shear flow. Thus for monodisperse linear polymer melts, for the first time a constitutive equation is presented which allows quantitative modeling of nonlinear extension and shear rheology on the basis of linear-viscoelastic data alone.