• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.14-17
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• 2012

Submicron silver particles were synthesized by chemical reduction with various room temperature ionic liquids. The size and distribution of silver particles were significantly affected by the anion type of ionic liquids and this is mainly attributed to the different abilities of the anions to coordinate with the silver particle, leading to various coagulation of silver particles. Among ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate was the most effective to synthesize submicron silver particles.

• Applied Chemistry for Engineering
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• v.20 no.6
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• pp.646-652
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• 2009

Present study deals with a three phase flow problem of determining drag acting on spheres wetted by liquid flow by gas flow through the spheres in simple cubic (SC), body-center cubic (BCC) and face-centered cubic (FCC) array, respectively, when the inertia of gas is negligibly small. The liquid flow driven by gravity on the spheres is assumed to be unaffected by the countercurrent gas flow. A perturbation method coupled with a multipole expansion method is used to calculate the hydrodynamic interactions between spheres and hence determine the effect of liquid film and flow on the gas flow for each periodic array of spheres. An approximate method for evaluating the effect of the liquid film is also presented for simple estimations. It is found that the approximation results are in a reasonable agreement with the numerical calculations.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.551-554
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• 2016

Silver particles were synthesized by chemical reduction with ionic liquids. Structure of silver particles were significantly affected by the cation parts of the ionic liquids. With increasing the length of the cation part, the smaller silver particles were formed regardless of the anion type. This is mainly attributed to the different stability of the ionic liquid structure formed by physical bond between cation parts. Among seven ionic liquids, [Omim][$PF_6$] was the most effective for synthesizing silver particles.

• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.505-512
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• 2006

Characteristics of particle holdup and heat transfer were investigated in a liquid-particle swirling fluidized bed whose diameter was 0.102 m and 2.5 m in height. Effects of liquid velocity, particle size and swirling liquid ratio($R_s$) on the particle holdup and immersed heater-to-bed overall heat transfer coefficient were examined. The particle holdup increased with increasing particle size and swirling liquid ratio but decreased with increasing liquid velocity.The local particle holdup was relatively high in the region near the heater when the $R_s$ value was 0.1~0.3, but the radial particle holdup was almost uniform when the $R_s$ value was 0.5, whereas, when the $R_s$ value was 0.7, the local particle holdup was relatively low in the region near the heater. The heat transfer characteristics between the immersed heater and the bed was well analyzed by means of phase space portraits and Kolmogorov entropy(K) of the time series of temperature difference fluctuations. The phase space portraits of temperature difference fluctuations became stable and periodic and the value of Kolmogorov entropy tended to decrease with increasing the value of $R_s$ from 0.1 to 0.5. The Kolmogorov entropy exhibited its maximum value with increasing liquid velocity. The value of overall heat transfer coefficient(h) showed its maximum value with the variation of liquid velocity, bed porosity or swirling liquid ratio, but it increased with increasing particle size. The value of K exhibited its maximum at the liquid velocity at which the h value attained its maximum. The particle holdup and overall heat transfer coefficient were well correlated in terms of dimensionless groups of operating variables.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.510-513
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• 2012

Palladium particles were synthesized by conventional chemical reduction method with ionic liquids. The size and shape of palladium particles were significantly affected by the cation parts of ionic liquids. This is mainly attributed to the different stabilities of the ionic liquid structure formed by the physical bond between the cation parts. Among ionic liquids with [$BF_{4}$] as an anion part, the hexyl substituent in the cation parts was more effective to synthesize palladium particles with the smaller size and more uniform shape.

• Journal of the Korea Computer Graphics Society
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• v.25 no.1
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• pp.13-22
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• 2019

In this paper, we propose a new method to improve the details of the fluid surface by removing liquid sheets that are over-preserved in particle-based water simulation. A variety of anisotropic approaches have been proposed to address the surface noise problem, one of the chronic problems in particle-based fluid simulation. However, a method of stably expressing the preservation and breakup of the liquid sheet has not been proposed. We propose a new framework that can dynamically add and remove the water particles based on anisotropic kernel and density to simultaneously represent two features of liquid sheet preservation and breakup in particle-based fluid simulations. The proposed technique well represented the characteristics of a fluid sheet that was breakup by removing the excessively preserved liquid sheet in a particle-based fluid simulation approach. As a result, the quality of the liquid sheet was improved without noise.

• The Korean Journal of Rheology
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• v.10 no.1
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• pp.1-6
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• 1998

액체와 액체를 교반할 경우 혹은 두가지 이상의 상이 함께 반응하는 화학공정의 경 우에서는 비상용성인 액체들을 난류조건하에 분산시켜 섞이게 한다. 부산계로 구성된 중합 반응기의 경우 분산입자의 크기는 최종제품의 생산성 및 품질에 큰 영향을 미치게 되므로 분산입자의 크기를 예측하는 것은 대단히 중요하다. 이러한 분산계에서 분산입자의 크기는 분산입자가 겪는 유동장에 의해 결정된다. 오일/오일 분산계로 이루어진 고분자 유탁액의 난류교반시 유동장은 종종 점성전단 부영역에 속하게 되는데 이경우의 분산입자의 크기를 예측하는 모델에 대한 연구는 별로 이루어지지않았다. 본연구에서는 오일/오일 분산계의 고 분자 유탁액에 대한 분산입자의 크기를 예측하는 모델식을 유체동력학적인 이론을 배경으로 하여 개발하였다. 개발한 모델식을 난류교반을 겪은 오일/오일 분산계를 거쳐 생산된 제품 인 내충격성 폴리스티렌으로 검증하여 모델식의 타당성을 입증하였다.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.405-408
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• 2012

$TiO_2$ particles with various shapes were synthesized by using a modified sol-gel method with binary ionic liquids. The structural properties of the particles were significantly affected by the composition of ionic liquids. This is mainly attributed to the interaction between the organic solvent and ionic liquid at the interface leading to the formation of particle structure. The photocatalytic activity of the prepared samples was also examined for the degradation of 4-chlorophenol. Among the particles, $TiO_2$ prepared with 1-octyl-3-methylimidazolium tetrafluoroborate and 1-octyl-3-methylimidazolium tetrafluoroborate showed the best photocatalytic performance.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.790-797
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• 2011

Hydrodynamic similarity was analyzed by employing scaling factor in three phase fluidized beds. The scaling factor was defined based on the holdups of gas, liquid and solid particles and effectivity volumetric flux of fluids between the two kinds of fluidized beds with different column diameter. The column diameter of one was 0.102 m and that of the other was 0.152 m. Filtered compressed air, tap water and glass bead of which density was 2,500 kg/$m^3$ were used as gas, liquid and solid phases, respectively. The individual phase holdups in three phase fluidized beds were determined by means of static pressure drop method. Effects of gas and liquid velocities and particle size on the scaling factors based on the holdups of each phase and effective volumetric flux of fluids were examined. The deviation of gas holdup between the two kinds of three phase fluidized beds decreased with increasing gas or liquid velocity but increased with increasing fluidized particle size. The deviation of liquid holdup between the two fluidized beds decreased with increasing gas or liquid velocity or size of fluidized solid particles. The deviation of solid holdup between the two fluidized beds increased with increasing gas velocity or particle size, however, decreased with increasing liquid velocity. The deviation of effective volumetric flux of fluids between the two fluidized beds decreased with increasing gas velocity or particle size, but increased with increasing liquid velocity. The scaling factor, which was defined in this study, could be effectively used to analyze the hydrodynamic similarity in three phase fluidized processes.

• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.313-316
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• 2009

Synthesis of porous $CeO_2$ particles was investigated using various ionic liquids (ILs) as an effective template. The pore structure and crystalline phase of $CeO_2$ particles was affected significantly by the composition of ionic liquids. The strength of the hydrogen bonds on the anion part of ionic liquid was an essential factor to form the pore architecture of $CeO_2$ particles. Moreover, the length of alkyl group on the cation part of ionic liquid determined the pore size and surface area of $CeO_2$ particles. Among the ionic liquids, it was found that 1-Buthyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) was the most effective ionic liquid to synthesize the porous $CeO_2$ particle.