• 한국세라믹학회지
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• 제29권12호
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• pp.919-925
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• 1992

Continuous synthesis process for monodispersed zirconia powders with ultrasonic wave mixing was developed. Reactant solutions were flowed through a T-tube with small diameter and then mixed in a microscale with ultrasonification. Reaction and aging were followed during the mixed solution of reactants is in plug flowing through a narrow long teflon tubing. Zr(n-OC4H9)4 in ethanol and H2O in ethanol were used as reactants. From this process monodispersed, spherical, non-agglomerated, singlet hydrated zirconia powders with 0.6 $\mu\textrm{m}$ average size were obtained. Geometrical standard deviation of the particle size distribution was less than 1.2 with ultrasonic mixing, and the geometrical standard deviation was not affected by the flow rate of the reactants.

• Journal of Advanced Marine Engineering and Technology
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• 제21권5호
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• pp.557-563
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• 1997

The unsteady flow in three-dimensional cubic cavity with narrow channel at upper region is investigated experimentally for three kinds of Reynolds number, 1*10/sup 4/, 3*10/sup 4/ and 5*10/sup 4/ based on the cavity width and cavity inlet mean flow velocity. Instant velocity vectors are obtained simultaneously at whole field by PIV(Particle Image Velocimetry). Wall pressure distributions are estimated using Poisson equation from the velocity data. Results of PIV reveal that severe unsteady flow fluctuation within the cavity are remarkable at all Reynolds numbers and sheared mixing layer phenomena are also found at the region where inlet driving flow is collided with the clock-wise rotating main primary vortex. Instant velocity profiles reveal that deformed forced vortex formation is observed throughout the entire region and spanwise kinetic energy migration is conspicuous.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.303-308
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• 2001

Recently, concrete structures have become larger and higher and are demanding high performance concrete with lower heat to prevent thermal cracking, far greater workability, high strength and durability, Application of low heat portland(Type IV) cement for the high performance concrete is the best solution to satisfied those requirements. Here are explained the effect on the properties of high flowing concrete using low heat portland cement by material and mixing variations. Variables for sensitivity test were selected items like finess modulus of aggregates, particle size of limestone powder, unit water, superplasticizer, viscosity agent and concrete temperature. The results of this study were be applied to slurry wall of #215 and #216 of underground LNG tank in Inchon.

• 한국연소학회지
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• 제3권1호
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• pp.41-48
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• 1998

A numerical study on combustion in a fluidized bed is based on three dimensional mixing and dispersion phenomena in the bed owing to the bubble growth in the vertical direction. As fluidizing velocities increase, bubble diameters increase, which activates the fuel dispersion in the bed. The combustion rates, however, reduce due to the decrease of gas exchange rates between bubble and emulsion phases. Fuel distributions in the bed are dependent on fluidizing velocities, equivalence ratios, fuel particle diameters, fuel feeding points, and the number of fuel feeders.

• 한국분말재료학회지
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• 제13권5호
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• pp.336-339
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• 2006

Magnetic properties of nanostructured materials are affected in complicated manner by their microstructure such as pain size (or particle size), internal strain and crystal structure. Thus, studies on the synthesis of nanostructured materials with controlled microstructure are necessary fur a significant improvement in magnetic properties. In the present work, nanostructured Fe-Co alloy powders with a grain size of 50 nm were successfully fabricated from the powder mixtures of (99.9% purity) $FeCl_2$ and $CoCl_2$ by chemical solution mixing and hydrogen reduction.

• 한국분말재료학회지
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• 제4권4호
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• pp.304-309
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• 1997

The synthesis of W-l5wt%Cu nanocomposite powder by hydrogen reduction of ball milled W-Cu oxide mixture was investigated in terms of powder characteristics such as particle size, mixing homogeneity and micropore structure. It is found that the micropores in the ball milled oxide (2-50 nm in size) act as an effective removal path of water vapor, followed by the formation of dry atmosphere at reaction zone. Such thermodynamic condition enhances the nucleation of W phase but suppresses the growth process, being in favor of the formation of W nanoparticles (about 21 nm in size). In addition, the superior mixing homogeneity of starting oxide mixture turned out to Play a significant role for forming extraordinary chemical homogeneity of W-l5wt%Cu nanocomposite powder.

• 대한화학회지
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• 제6권2호
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• pp.122-124
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• 1962

The silver halide precipitate tends to separate in curdy form of flocculated colloid when it is precipitated by direct mixing of reactant solutions. This type of precipitate has a great tendency to adsorb or occlude foreign ions in the solution.When silver halide in precipitated from homogeneous solution using the slow hydrolysis of Alkyl halide or Ally halide, the precipitate becomes dense, filterable and uniform in particle size which is very advantageous in gravimetric analysis.We found that silver halide precipitates obtained from homogeneous solution with hydrogen halide formed by the hydrolysis of alkyl halide do not give the color change with fluorescein as adsorption indicater, while silver halide precipitates obtained by direct mixing method give sharply pink color which appear to be uniformly distributed through the solution in silver ion excess.

• 상하수도학회지
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• 제21권6호
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• pp.717-726
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• 2007

Fully-grown flocs in a mixing tank of membrane filtration with dead-end membrane are ruptured while passing through a pump and the ruptured flocs are aggregated again in a Membrane-Feed-Pipe (MFP). To look at more details, this study tries to relate the reaggregation to a parameter of mixing intensity in MFP, i.e., G-value. The G-value is a function of Reynolds number, pipe diameter, friction factor and average velocity in MFP. To deal with polydispersity condition, we develop a representative particle size called in this study EDPD (Effective Diameter for Polydispersity condition in Dead-end filtration). The experimental results show that as the G-value increases, the EDPD decreases and also the cake resistance increases. Through comparison between EDPD and cake resistance, these results show that cake resistances are controlled by reaggregation phenomenon in MFP. The effect of detention time in MFP, however, does not affect the reaggregation of the broken flocs as G-values are increased.

• 한국응용과학기술학회지
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• 제28권2호
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• pp.247-250
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• 2011

The excess volumes of mixing of benzyl alcohol and halothane in vesicle and in suspensions of several lipids have been determined at $25^{\circ}C$ it using a excess volume dilatometer. The potency of general anesthetics has long been known to correlate with lipid solubility. Denaturations of the vesicle, which is a sole membrane protein in the purple membrane of Halobacteriun Halobium, were studied by absorption changes at 280 nm and fluorescence changes at 330 nm and excess volume dilatometer. The particle size analysis of viscous polymer solutions by diffusional interchange is the key step by measurement. The excess volume of mixing in chitosan was found to be negative, whereas them of purple membrane, Halobacteriun Halobium and red membrane were positive in benzyl alcohol and halothane. This result was confirmed as Miller's supposition.

• 한국분말재료학회지
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• 제11권5호
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• pp.391-398
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• 2004

Calcium phosphate powders were successfully synthesized by using re-cycled eggshell and phosphoric acid. The crystallization behavior and powder morphologies of the synthesized powders were dependent on the starting condition of the eggshell, the mixing ratio and method of the eggshell and phosphoric acid, and calcination temperature. In general, $\beta$-tricalcium phosphate was stably synthesized at about $900^{\circ}C$ for 1h at each proper mixing ratio. And, the synthesized powders showed the similar microstructures to the morphology of original eggshell with uniform particle sizes. In this study, the calcium phosphate powders were synthesized with eggshell in various processing method. And their unique microstructures obtained from the eggshell were also. observed. The crystalline developments and microstructures of the synthesized powders were examined by X-ray diffractometer and scanning electron microscopy.