• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.278-283
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• 2016

In this study, we have for the first time applied fractional precipitation with hydrophilic polymer in order to decrease the particle size of the anticancer agent paclitaxel from plant cell cultures. When compared with the case where no hydrophilic polymer was employed, the addition of hydrophilic polymer in fractional precipitation resulted in a decrease in the size of the paclitaxel precipitate. Among the polymers used, HPMC 2910 was the most effective for inhibition of precipitate growth. A polymer concentration of 0.2% (w/v) obtained the smallest particle size. The particle size was reduced by ~35% compared to control. In addition, the precipitate size was inversely correlated with the absolute value of the zeta potential.

• Particle and aerosol research
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• v.9 no.4
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• pp.253-260
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• 2013

For a vertical atmospheric aerosol distribution measurement, a very compact and light particle sampling package is developed. This package includes a compact optical particle counter (Hy-OPC), a light and small condensation particle counter (Hy-CPC), sensors (GPS, wind velocity, temperature, humidity), and a communication and system control board. This package is attached to He balloon and the altitude is controlled by a winch. Using this system the vertical particle size distribution was measured. The test results showed that the ground base atmospheric particle measurement result may be a lot different from that high above the ground.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.113-121
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• 1999

Diesel particulate matter is known to be one of the major harmful emissions produced by diesel engines. Diesel particulates are subject to diesel emission regulations and have lately become the focus in the diesel emission control technology. Thus, the aftertreatment system is adopted at the diesel engine exhaust to reduce the particulate emission. Although this benefit is recognized, it is not clear how the aftertreatment system influences quantitatively the particle size distribution distribution. In this study, the particle size distributions of diesel exhaust were measured using the scanning mobility particle sizer with and without the aftertreatment system. There results showed that the diesel particulate filter and plasm system reduced the number of emitted particles by more than 90% and about 80% respectivley in the particle size range of 20nm∼600nm. On the other hand no significant effect of the diesel oxidation catalyst on the particle number concentration was detected.

• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.65-73
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• 2010

In order to provide fundamental information for developing reaction model in the practical blended coal power plants, effects of particle size and blending ratio on combustion characteristics and thermal reaction in co-firing with bituminous and sub-bituminous coals were experimentally investigated using a TGA and a laboratory-scale burner. Characteristic parameters including ignition, burnout temperature and activation energy were determined from TG and DTG combustion profiles. Distributions of flame length and mean particle temperature were investigated from the visualization of flames in slit-burner system. As coal particle size decreased and volatile matter content increased, characteristic temperatures and activation energy decreased. The ignition/burnout characteristics and activation energy are linearly influenced by a variation in particle size and blending ratio. These results indicated that the control of the coal blending ratio can improve the combustion efficiency for sub-bituminous coals and the ignition characteristics for bituminous coals.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.753-759
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• 2000

Photoelectric charging is a very efficient way of charging small particles. This method can be applied to combustion measurement, electrostatic precipitator, metal separation and control of micro-contamination. To understand the photoelectric charging mechanism, particle charging of silver by exposure to ultraviolet is investigated in this study. Average charges and charge distributions are measured at various conditions, using two differential mobility analyzers, a condensation nucleus counter, and an aerosol electrometer. The silver particles are generated in a spark discharge aerosol generator. After that process, the generated particles are charged in the photoelectric charger using low-pressure mercury lamp that emits ultraviolet having wavelength 253.7 nm. The results show that ultra-fine particles are highly charged by the photoelectric charging. The average charges linearly increase with increasing particle size and the charge distribution change with particle size. These results are discussed by comparison with previous experiments and proposed equations. It is assumed that the coefficient of electron emission probability is affected by initial charge. The results also show that the charge distribution of a particle is dependent on initial charge. Single changed particle, uncharged particle and neutralized particle are compared. The differences of charge distribution in each case increase with increasing particle size.

• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.31-36
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• 2013

${\beta}$-SiC powders were synthesized by a carbothermal reduction process using $SiO_2$-C precursors fabricated by a sol-gel process using phenol resin and TEOS as starting materials for carbon and Si sources, respectively. The C/Si molar ratio was selected as an important parameter for synthesizing SiC powders using a sol-gel process, and the effects of the C/Si molar ratio (1.4-3.0) on the particle size, particle size distribution, and yield of the synthesized ${\beta}$-SiC powders were investigated. It was found that (1) the particle size of the synthesized ${\beta}$-SiC powders decreased with an increase in the C/Si molar ratio in the $SiO_2$-C hybrid precursors, (2) the particle size distribution widened with an increase in the C/Si molar ratio, and (3) the yield of the ${\beta}$-SiC powder production increased with an increase in the C/Si molar ratio.

• Journal of Powder Materials
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• v.19 no.1
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• pp.60-66
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• 2012

In this study, Platinum(Pt) nanoparticles were synthesized by using polyol process which is one of the liquid phase reduction methods. Dihydrogen hexachloroplatinate (IV) hexahydrate $(H_2PtCl_6{\cdot}6H_2O)$, as a precursor, was dissolved in ethylene glycol and silver nitrate ($AgNO_3$) was added as metal salt for shape control of Pt particle. Also, polyvinylpyrrolidone (PVP), as capping agent, was added to reduce the size of particle and to separate the particles. The size of Pt nanoparticles was evaluated particle size analyzer (PSA). The size and morphology of Pt nanoparticles were observed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM). Synthesized Pt nanoparticles were studied with varying time and temperature of polyol process. Pt nanoparticles have been successfully synthesized with controlled sizes in the range 5-10 and 20-40 nm with cube and multiple-cube shapes.

• Polymer(Korea)
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• v.27 no.5
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• pp.493-501
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• 2003

Poly(methyl methacrylate) (PMMA) particles, denture base resin, were synthesized by suspension polymerization through control of polymerization conditions (stabilizer concentration, co-monomer concentration, and the agitation speed) and evaluated changes in molecular weight and particle size. We also investigated their mechanical properties of compression-molded samples which were from synthesized polymer powder mixed with methyl methacrylate (MMA) solution. under the condition of volumetric ratio as 2:1(PMMA powder and MMA solution). The results shows that the mechanical properties were mainly affected by particle size over 100 ${\mu}$m (in particle size) and by molecular weight under 100 ${\mu}$m (in particle size). From these results, we concluded that the most appropriate particle size of PMMA powder for heat-cured denture base resins is around 100 ${\mu}$m. and its molecular weight is around 300000 (M$\sub$n/).

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.252-261
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• 1991

A particle trajectory model to simulate two-phase particle-laden crossjets into two-dimensional horizontal free stream has been developed to study the variations of the jet trajectories and velocity variations of the gaseous and the particulate phases. The following conclusions may be drawn from the predicted results, which are in agreement with experimental observations. The penetration of the two-phase jet in a crossflow is greater than that of the single-phase jet. The penetration of particles into the free stream increases with increasing particle size, solids-gas loading ratio and carrier gas to free stream velocity ratio at the jet exit. When the particle size is large, the solid particles separate from the carrier gas , while the particles are completely suspended in the carrier gas for the case of small size particles. As the particle to carrier gas velocity ratio at the jet exit is less than unity, the particles in the vicinity of the jet exit are accelerated by the carrier gas. As the injection angle is increased, the difference of the particle trajectory from that of the pure gas becomes larger. Therefore, it can be concluded that the velocities and trajectories of the particle-laden jets in a crossflow change depending on the solids-gas loading ratio, particle size, carrier gas to free stream velocity ratio and particle to gas velocity ratio at the jet exit.

• Journal of the Korean Society of Food Culture
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• v.34 no.3
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• pp.334-342
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• 2019

In this study, the effects of different varieties and particle sizes of dry milled rice flour on Jeolpyeon quality were investigated. Classify particle size of dry milled rice flour according to rice variety into 50, 100, and $150{\mu}m$. A particle size of $50{\mu}m$ in the varieties Boramchan and Hanareum resulted in the highest damaged starch contents (p<0.05). Additionally, the Boramchan and Hanareum varieties had the highest water absorption index (WAI) values (p<0.05). Analysis of the gelatinization characteristics of dry milled rice flour according to varieties revealed the peak viscosity of Dasan and Hanareum was high (p<0.05), regardless of particle size, while the breakdown was highest for Hanareum at all particle sizes (p<0.05). The moisture content of Jeolpyeon made with Boramchan varied between 48.83 and 53.64% among particle sizes, with no significant differences relative to the control. The hardness of the control was 3.15 kg, while the hardness of Jeolpyeon made with Boramchan decreased significantly 2.60-2.63 kg (p<0.05).