• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.930-936
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• 1999

For LiMn2O4 based spinel structures the stoichiometric reaction conditions need be considered carefully because the electrical properties depend on the structural stability. In order to obtain the homogeneous compound the Pechini process was chosen which could obtain a stoichiometry phase even low temperature and dependency of the synthetic condition on structural stability and electrochemical performance was investigated. X-ray diffraction studies showed that the compounds doped with transition metal have smaller lattice constants than those un doped. The dc conductivity was evaluated by a four probe method in the low and high temperature region respectively. The variations of basal spacings for the cathode were detected to be dependent on the extent of current flows (under dc)

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.2
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• pp.254-262
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• 1996

$Pb(Zr_{0.52}Ti_{0.48})O_{3}$ (PZT) ceramics were prepared with uniform particle size of $1~3\;\mu\textrm{m}$ by hydrothermal synthesis at various conditions, such as hydrothermal reaction temperature, concentration of mineralizer and reaction time. PZT ceramics were formed above $180^{\circ}C$ for 2 hrs reaction using 10 M KOH solution as a mineralizer, but reaction condition was slightly different by starting materials. Morphology and characterization of PZT powders were investigated by XRD and SEM. By increasing the reaction temperature, KOH concentration and reaction time, the composition of the PZT phase tended to be homogeneous phase.

• International Journal of Concrete Structures and Materials
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• v.2 no.2
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• pp.83-90
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• 2008

Permeability to vapor and water among other performances required for finishing materials is dealt with in this study. The relative moisture content of concrete coated/covered with a finishing material was experimentally investigated while changing the environmental conditions including temperature, relative humidity, and rainfall. An organic paint (water-based urethane), organic synthetic resin emulsion-type film coating (film coating E), and inorganic porcelain tiles were selected as the finishing materials. When compared from the aspect of vapor and water permeability, the vapor permeability and water permeability of water-based urethane were high and low, respectively; those of film coating E were high and high, respectively; and those of porcelain tiles were low and low, respectively. This means that the moisture state of concrete structures is governed not only by the environmental conditions but also by the performance of finishing materials. It is therefore of paramount importance to appropriately select a finishing material to address the specific deteriorative factors involved in the concrete structure to be finished.

• Journal of the Korean Society of Combustion
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• v.7 no.2
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• pp.42-48
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• 2002

Experiments on burning process of the industrial wastes were performed on a nozzle-type grate in the industrial waste incinerator with a capacity of 160 kilograms per hour. The temporal variations of temperatures and concentrations of the exhaust gas were measured and analyzed. The synthetic leather waste with the moisture content less than 2% was used. The experimental results show that the CO concentration in the exhaust gas exceeds the limit, 600 ppm, and the gas temperature fluctuates too much when 8 kg of waste was supplied every 3 minutes, equivalent to the capacity of 160kg per hour. That is a typical burning mode of this high-calorific industrial waste. When the smaller unit waste input, 6kg per every 2 min 15 seconds was supplied, we could reduce the fluctuations of the furnace temperature and improve the exhaust emissions, especially the CO concentration.

• Journal of environmental and Sanitary engineering
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• v.11 no.3
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• pp.13-19
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• 1996

Packed bed reactor containing immobilized microorganisms which degraded phenol without growth was used to remove phenol from the synthetic wastewater. The effects of temperature, retention time(reactor volume/flow rate) and phenol concentration on the removal efficiency of phenol were investigated. The effect of temperature in the range of 20-30$\circ $C was negligible while retention time and phenol concentration influenced the removal of phenol significantly. When retention time was in the range of 1-1.5 hour, the removal efficiency of phenol was affected not by phenol concentration but by retention time itself while it was influenced by phenol concentration above 1.5 hour of retention time. The beads after 720 hours operation were swelled by 40 % in diameter which could be prevented by crosslinking with glutaraldehyde at the expense of cell activity.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.136.2-136.2
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• 2011

A dynamic simulation study on SCR process in GTL process was carried out in order to find optimum operation conditions for pilot plant operation. Optimum operating conditions for SCR synthesis gas process were determined by changing operation variables such as feed temperature and pressure. It was also assumed that physical properties of reaction medium were governed by RKS (Redlich-Kwong-Soave) equation. The effect of temperature and pressure on synthesis gas process $H_2$/CO ratio were mainly examined. Dynamic simulation results were fed back to feed operation condition for optimizing productivity, especially for appropriate condition to FT (Fischer-Tropsch) synthesis unit.

• Macromolecular Research
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• v.17 no.1
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• pp.37-43
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• 2009

To fabricate dental nanocomposites containing finely dispersed silica nanoparticles, nearly monodispersed silica nanoparticles smaller than 25 nm were synthesized without forming any aggregates via a modified sol-gel process. Since silica nanoparticles synthesized by the Stober method formed aggregates when the particle size is smaller than 25 nm, the synthetic method was modified by changing the reaction temperature and adding poly(1-vinyl-2-pyrrolidinone) (PVP) to the reaction mixture. The size of the formed silica nanoparticles was reduced by increasing the reaction temperature or adding PVP. Furthermore, the formation of aggregates with primary silica nanoparticles smaller than 25 nm was prevented by increasing the amount of PVP added to the reaction mixture. To enhance the dispersion of the silica particles in an organic matrix, the synthesized silica nanoparticles were treated with 3-methacryloxypropyltrimethoxysilane ($\gamma$-MPS). A dental nanocomposite containing finely dispersed silica nanoparticles could be produced by using the surface-treated silica nanoparticles.

• Journal of the Korean Ceramic Society
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• v.34 no.7
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• pp.747-757
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• 1997

ZSM-5 zeolite composite membranes have been synthesized from a silica sol solution containing TPABr as an organic template by the dip-coating and the pressurized-coating hydrothermal treatment techniques. The CO2 separation efficiency of synthesized composite membranes was also investigated. The permeation mechanism of CO2 through ZSM-5 membranses was the surface diffusion, and that of N2, O2, and He gases was Knudsen diffusion or activated diffusion depending on the synthetic method of membranes and the measurement temperature. The CO2/N2 separation factor of the membrane prepared by the dip-coating hydrothermal treatment was 2.5 at about 12$0^{\circ}C$, while the ZSM-5 composite membrane synthesized by the pressurized-coating hydrothermal treatment technique showed the CO2/N2 separation factor of 9.0 at room temperature higher than that ever reported in the literature.

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.732-737
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• 2018

Experimental data of phase equilibria are reported for the binary mixture of 1-phenyl-2-pyrrolidone in supercritical carbon dioxide. Phase behavior data was measured in a synthetic method at a temperature ranging from 333.2 to 393.2 K and at pressures up to 97.14 MPa. The solubility of 1-phenyl-2-pyrrolidone in the carbon dioxide + 1-phenyl-2-pyrrolidone system increased as temperature increased at a constant pressure and it exhibited the type-I phase behavior. The experimental data for the binary mixture were correlated with the Peng-Robinson equation of state using mixing rule and the critical properties of 1-phenyl-2-pyrrolidone were predicted with the Joback and Lyderson method.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3001-3006
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• 2008

Recently, the internal combustion engines have focused on reducing both the CO2 emissions in order to cope with severe regulations for greenhouse effect. Therefore, various new technologies have been developed in many countries. Among them, the cooling system is spotlighted because it has great effect on fuel efficiency. However, the present engine cooling system is almost same as one of the 50 years ago. The needs for high performance and compact size make it important to improve engine cooling system, down-sizing and control method of coolant flow. Thus, low fuel consumption technology such as control and synthetic management of cooling system was necessary to satisfy with these needs. In this study, we applied electric thermostat to improve the fuel economy. The fuel consumption was compared after driving FTP-75 mode on both conditions which were with a conventional wax thermostat and with a electric thermostat. The coolant temperature of opening the electric thermostat is higher.