• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.47-50
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• 2003

Carbon-silica membranes were Prepared by Pyrolyzing polyimide/silica composite obtained from ill-situ polymerization of alkoxy silanes via sol-gel reaction. In this study, effects of silica content and silica network in polyimide matrix were focused on the gas permeation and separation properties of the final carbon-silica membrane. The membranes prepared were characterized with a field emission scanning electron microscopy (FE-SEM), a solid state $^{29}$ Si nuclear magnetic resonance spectroscopy ($^{29}$ Si-NMR), an electron spectroscopy for chemical analysis (ESCA), a thermogravimetric analysis (TGA) and gas permeation tests.

• Journal of Institute of Convergence Technology
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• v.4 no.2
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• pp.47-50
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• 2014

Voloxidation is a process for converting $UO_2$ into $U_3O_8$ while removing some volatile products in spent fuels (SF). Various oxidative gas conditions including air and mixture of Ar and $O_2$ could be adopted for the process. The gas flows into a reactor under high temperature ($>500^{\circ}C$) and components of SF are reacted with the gas. SF is composed of various components such as actinides, lanthanides, and alkali metals. Therefore, it is of significance to understand their behavior during the reactions for process development. However, due to the limit of available experiments, phase diagram analysis should be preceded. TPP diagram is constructed with respect to temperature-pressure-pressure. It shows a stable phase depending on partial pressures of gas components as well as temperature. In this work, we investigated TPP diagrams for actinides, lanthanides and other oxides to determine stable oxide forms under different gas conditions. The results would be used to set up a material balance under a pyroprocessing scheme of SF and compare the gas conditions for the optimization of fission products removal.

• Journal of the Korean Ceramic Society
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• v.49 no.4
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• pp.279-286
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• 2012

Microstructure tailoring of filler loaded preceramic polymer systems offers a high potential for property improvement of Si-based ceramics and composites. Advancements in manufacturing of bulk materials by controlling microstructure evolution during thermal induced polymer-ceramic transforma-tion and polymer-filler reactions will be presented. Rate controlled pyrolysis, multilayer gradient laminate design and surface modification by gas solid reaction are demonstrated to yield ceramic components of high fractional density and superior mechanical properties. Emerging fields of applications are presented.

• Journal of the Korean Ceramic Society
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• v.38 no.1
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• pp.9-14
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• 2001

본 연구는 우리나라 하동지방에서 다량으로 산출되는 저급 Kaoline을 활용하여 Mullite를 합성하는데 목적이 있다. 저질 Kolin을 AlF$_3$와 충분히 혼합한 후 130$0^{\circ}C$에서 반응시키면 거의 순간적으로 Mullite의 합성이 가능하였으며 이때에 얻어진 Mullite는 X-ray 회절결과 순수한 Mullite 단일상으로 나타났으며 소결체의 특성에 보면 1$600^{\circ}C$ 3시간 소결 후 비중은 2.8g/$m^2$이며 굽힘강도는 170 MPa을 나타내었다.

• Clean Technology
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• v.21 no.1
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• pp.53-61
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• 2015

In this study, we have investigated the kinetics on the char-CO₂ catalytic gasification reaction. Thermogravimetric analysis (TGA) experiments were carried out for char-CO₂ catalytic gasification of an Indonesian Kideco sub-bituminous. Na₂CO₃ and K₂CO₃ were selected as catalysts which were physically mixed with coal. The char-CO₂ catalytic gasification reaction showed a rapid increase of carbon conversion rate at 850 ℃, 60 vol% CO₂, and 7 wt% Na₂CO₃. At the isothermal conditions ranging from 750 ℃ to 900 ℃, the carbon conversion rates increased as the temperature increased. Four kinetic models for gas-solid reaction including the shrinking core model (SCM), random pore model (RPM), volumetric reaction model (VRM), and modified volumetric reaction model (MVRM) were applied to the experimental data against the measured kinetic data. The gasification kinetics were suitably described by the MVRM for the Kideco sub-bituminous. The activation energies for each char mixed with Na₂CO₃ and K₂CO₃ were found 55-71 kJ/mol and 69-87 kJ/mol.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.543-546
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• 2017

Test equipment was designed and manufactured to evaluate thermal reaction characteristic of internal insulators of solid rocket motor. Test is allowed up to chamber pressure 2,500 psi, burn-time 40 s. It is possible to observe and to compare thermal reaction characteristic for a few materials simultaneously, under the condition that the ablation occurs. In efficient average chamber pressure 878 psi, efficient burn-time 10.7 s and gas velocity 100 m/s, test was executed for confirming safety of equipment, being 4 test materials inserted simultaneously. Basic data for understanding thermal characteristic of internal insulator, that is, pressure-time curve, temperature-time curve in the test sample, and thermal destruction depth of test samples was gained successfully.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.99-106
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• 2017

In this study, mixed catalytic char gasification of Indonesia low-rank coal Kideco was investigated under nitrogen atmosphere and isothermal conditions at a fixed reactor. The effects of the temperature were investigated at various temperature (700, 750, 800, $850^{\circ}C$). The effects of blend ratio of catalysts ($K_2CO_3$, Ni) were investigated with different blend ratios (1:9, 3:7, 5:5, 7:3 and 9:1). The sample was prepared by mixing with $K_2CO_3$ physically and by ionexchange method with Ni. The data from thermogravimetric analyzer and gas chromatography were applied to four gassolid reaction kinetic models including shrinking core model, volumetric reaction model, random pore model and modified volumetric reaction model.

• Journal of Sensor Science and Technology
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• v.7 no.5
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• pp.319-326
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• 1998

Anodic half-reaction in the $Na^+$ ionic sensors using $Na_2CO_3$ and $MCO_3$ ($M=Cs_2,K_2,Li_2,Ca$) as a sensitive membrane is derived in continuous flow system to explain $CO_2$ sensing characteristics. For various gas-sensitive membranes, a well known overall reaction, $MCO_3\;=\;MO\;+\;CO_2$, cannot be applied for the EMF behaviors of these kinds of sensors. So, the anodic reaction is found to involve $Na_2CO_3$ and $M^{++}$-containing oxide phases by employing the ion exchange reaction at the interface of solid electrolyte and the sensitive membrane to maintain ionic balance in the whole cell. Based on the electrode reaction derived in flow system, differences of cell potentials between continuous and discontinuous flow systems were also discussed. These EMF differences were considerably caused by the partial pressures of oxygen and $CO_2$ as well as irreversible chemical reactions between electrode materials and $CO_2$ atmosphere.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.11
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• pp.1627-1633
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• 2012

This study was to evaluate the feasibility of recycling the solids separated from swine wastewater treatment process as a fuel source for heat production and to provide a data set on the gas emissions and combustion properties. Also, in this study, the heavy metals in ash content were analyzed for its possible use as a fertilizer. Proximate analysis of the solid recovered from the swine wastewater after flocculation with organic polymer showed high calorific (5,330.50 kcal/kg) and low moisture (15.38%) content, indicating that the solid separated from swine wastewater can be used as an alternative fuel source. CO and NOx emissions were found to increase with increasing temperature. Combustion efficiency of the solids was found to be stable (95 to 98%) with varied temperatures. Thermogravimetry (TG) and differential thermal analysis (DTA) showed five thermal effects (four exothermic and one endothermic), and these effects were distinguished in three stages, water evaporation, heterogeneous combustion of hydrocarbons and decomposition reaction. Based on the calorific value and combustion stability results, solid separated from swine manure can be used as an alternative source of fuel, however further research is still warranted regarding regulation of CO and NOx emissions. Furthermore, the heavy metal content in ash was below the legal limits required for its usage as fertilizer.

• Journal of the Korean institute of surface engineering
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• v.25 no.5
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• pp.215-221
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• 1992

This research is aimed at developing(110) preferred TiS2 cathode films and glass typed solid electro-lytes which have high ionic migrations and low electron conductivities for thin secondary solid batteries. To obtain preferred oriented TiS2 thin films on a substrate by CVD method using TiCl4 and H2S gases three factors of heating temperature, inner pressure of furnace and TiCl4/H2S gas mole fraction were ex-amined systematically. To obtain solid films of Li2O-B2O3-SiO2 electrolytes by r.f. sputtering for thin proto-type batteries of Li/Li2O-B2O3-SiO2TiS2, sputtering conditions were examined. TiS2 cathode films showed columnar structure, namely c axis oriented parallely. At low pressure of reaction chamber and low heating temperature, surface of smooth TiS2 films couldd be obtained. Ionic conductivity of Li2O-B2O3-SiO2 films manufactured by r.f. magnetron sputtering were 3$\times$10-7$\Omega$-1cm-1 and electron conductivities were 10-11$\Omega$-1cm-1. Open cell voltage of thin lithium batteries were 2.32V with a designed prototype cell.