• Journal of the Korean Ceramic Society
• /
• v.38 no.9
• /
• pp.853-859
• /
• 2001

The dispersion stability of nano $Y_2O_3-CeO_2$ system was investigated using colloid surface chemistry. Green body of $Y_2O_3$ doped $CeO_2$ was prepared by slip casting in and aqueous system. The dispersion stability of suspension between powders and organic additive was accomplished through electrokinetic behavior of suspension, which was done by ESA apparatus. The dynamic mobility of particles was enhanced when the anionic dispersant of the amount of 1wt% was added. The dissolution of $Y^{3+}$ ion in suspension occurred in the acidic region so that pH value in slurries did not move to below 7.0. In the $CeO_2-Y_2O_3$ system, optimal preparation of suspension was made after adding the anionic dispersant as the amount of 1wt% and pH value of 11.0, and then slip-cast and sintered at 1400$^{\circ}$C, 2 hrs. It appeared relative density of >98% and homogeneous distribution of Y element in depth direction as well as in the microstructure of surface.

• Journal of Advanced Marine Engineering and Technology
• /
• v.34 no.5
• /
• pp.653-660
• /
• 2010

The stern tube bearing is installed to the stern tube and stern boss casting by using the method of the force pressured fitting. The adequate value of the interference between the stern tube bearing and casting should be considered owing to the slip. In this study, to review and compare the fitting force and the contact pressure, the theory of thick walled cylinder is considered to clarify the formula which received from the maker. Also the fitting force and contact pressure are calculated by using the standard value of interference, Young's modulus, Poisson's ratio and friction coefficient.

• Journal of the Korean Ceramic Society
• /
• v.37 no.11
• /
• pp.1058-1064
• /
• 2000

연속슬립캐스팅 및 상압소결법으로 $Al_2$O$_3$/ZrO$_2$적층복합체를 제조하였으며, 적층복합체에서 ZrO$_2$층을 단사정, 정방정 및 입방정으로 각각 달리 적층하여 균열생성 및 전파 거동에 미치는 ZrO$_2$상의 영향을 고찰하였다. 균열 생성은 냉각시 $Al_2$O$_3$층과 ZrO$_2$층 간의 열팽창 계수의 차이에 의한 열적불일치응력이 가장 큰 요인으로 작용하였다. 적층체 내에 존재하는 균열은 tetra-ZrO$_2$의 경우 적층두께 조절로 가능하였으며, cubic-ZrO$_2$의 경우는 냉각속도 조절로 균열밀도로 크게 낮출 수 있었다. $Al_2$O$_3$/ZrO$_2$적층체를 구성하는 세가지 ZrO$_2$상(mono, tetra, cubic)들 중에서 cubic-ZrO$_2$가 포함된 적층체의 경우 $Al_2$O$_3$와 ZrO$_2$계면에 형성된 잔류압축응력으로 인한 균열굴절 효과를 얻을 수 있었다.

• Korean Journal of Environmental Agriculture
• /
• v.22 no.2
• /
• pp.124-129
• /
• 2003

The objectives of this study are to manufacture an efficient $TiO_2$, photocatalyst and to delineate optimum operational parameters for TCE (trichloroethylene) degradation in a photocatalytic oxidative reactor. The $TiO_2$ photocatalyst irradiated by 365 nm UV light is expected to increase degradation of TCE in solution by a series of photocatalytic oxidations in the reactor. A new membrane $TiO_2$ photocatalyst wns eventually developed by coating a mixture of Davan-C(0.24 wt%) and PVA(0.16 wt%) on the surface of slips using the slip-casting method. Results show that increase in the number of coating of $TiO_2$ sol on surface of photocatalysts and in the surface thickness improved the endurance and photocatalysts, but these physical modifications caused significant decrease in the overall degradation efficiency of TCE. Pre-aeration or recirculation of the influents to the reactors containing TCE increased degradation efficiency of TCE. The optimum operational conditions far the surface area of photocatalysts and UV light intensity appeared to be $1.47\;mL/cm^2$ and $225\;W/cm^2{\times}100$, respectively, in the reactor. Based on the overall experimental results, the photocatalytic oxidation of TCE with the new membrane $TiO_2$ photocatalyst is found to be very effective under the operational conditions delineated in this study.

• Membrane Journal
• /
• v.27 no.2
• /
• pp.199-204
• /
• 2017

In this study, a study was carried out for the separation of metal ions in lignin extract discharged from the pulp process. alumina powders were mixed with DMAc (N, N-dimethylacetamide) solvent and PESf (Polyethersulfone) polymer, PVP (polyvinylpyrrolidone) dispersant was added and slip casting method was used to prepare the membrane. The membrane was measured for pore size through a CFP (Capillary Flow Porometer) device and the surface and cross-section of the membrane were observed through a FE-SEM (Field Emission Scanning Electron Microscope). The flux was calculated by measuring the filtered weight per hour using a separation experiment device. Pore size measurements were performed under increasing pressure from 0 psi to 30 psi. The pore size of the membrane was $0.4{\mu}m$ and the flux decreased from the initial flux value of $6.36kg{\cdot}m^{-2}{\cdot}h^{-1}$ to $1.98kg{\cdot}m^{-2}{\cdot}h^{-1}$ due to the fouling of the membrane. After the permeation experiment, membrane contaminants were removed by simple washing. Separation experiments showed that Na contained in the initial lignin extract was reduced by 69%, Fe was removed by 87%, K by 95%, Ca by 93% and Mg by 96%.