• Journal of Korean Society of Environmental Engineers
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• v.27 no.12
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• pp.1270-1276
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• 2005

When gas/particle partitioning of PAHs in the atmosphere approached an equilibrium state, the slope of linear regression between gas/particle partitioning coefficient($logK_p$) and subcooled liquid vapour pressure($logP_L^O$) was -1. But it was alleged that the slope of equilibrium state might not be -1 in real atmospheric environment due to heterogeneous characteristics of particulate matter. In This study, it would be found if gas/particle partitioning of PAHs segregated with particle size in equilibrium state was based on the hypothesis mentioned above. We have calculated the slopes of $logK_p$ v.s. $logP_L^O$ after collecting 10 set samples which consisted of particulate and vaporous phases. The slope was close to -1 in equilibrium states. But despite of equilibrium state, all slopes segregated with particle size were not close to -1 and those were gentler with larger particle size. The difference of slopes in equilibrium states was almost against the assumption of gas/particle partitioning theory. When the gas/particle partitioning was due to adsorption, the desorption enthalpy was different in each particle size. When it was absorption, the activity coefficient was different. The difference of desorption enthalpy and activity coefficient in each particle size indicate the heterogeneous characteristics of the bulk particle. This may be the reason for slope variation with particle size even though in an equilibrium state.

• The Korean Journal of Food And Nutrition
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• v.8 no.1
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• pp.17-22
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• 1995

The effect of particle size of raw material on the field of extract and changes in composition of Ssang Wha Tang was investigated during manufacturing. As the size of particle was decreased the yield was increased. The yield of extract increased as much as double times as the diameter of the particle decreased from 10 m to 1 m. But the composition of extract was not varied much as the diameter of the particle differed. From these results, it is concluded that cutting method affects the productivity of Ssang Wha Tang.

• Journal of the Korean Graphic Arts Communication Society
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• v.16 no.2
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• pp.11-22
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• 1998

For the purpose of preparation of monodispersed spherical zinc oxide fine particles, an experimental research on the preparation of zinc oxide particles from zinc salts solutions by high temperature precipitation reaction was performed. Zinc oxide particles were precipitated from all the precipitation solutions tested if the precipitation temperature was higher than 60$^{\circ}$. As the precipitation temperature Increased until 80$^{\circ}$, the average particle diameter of zinc oxide particles decreased and the narrower particle size distribution were obtained. Spherical zinc oxide fine particles with relatively narrow particle size distribution were precipitated from the ZnSO$_4$ solutions with NaOH as precipitant. Final pH of precipitation solution had an effect on the amount of zinc oxide precipitated, but had no effect on the their particle size or size distribution.

• Fire Science and Engineering
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• v.10 no.1
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• pp.44-48
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• 1996

Burning rate of immobilized methyl and ethyl alcohols on ceramic balls was studied. Experiments were performed by burning methyl, ethyl alcohols immobilized on sands (particle size 0.35mm) and ceramic balls (particle size 1-5mm) to measure mass burning rate, height burning rate and combustion temperature. The longer time from ignition to extinguishment was resulted from the larger particle size of ceramic balls and the smaller size of ceramic balls exhibited the higher mass burning rate. Of alcohols tested the relative magnitude of facilitation of combustion was methyl ＞ ethyl. Combustion temperature of alcohols, without regard to the types of alcohols, was not increased with smaller ceramic balls(up to 3mm of particle size). However, with larger ceramic balls, combustion temperatare of alcohols was increased by 40-50$^{\circ}$ and the highest combustion temperatare was obtained with sands (particle size 0.35mm).

• Korean Journal of Materials Research
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• v.17 no.10
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• pp.532-537
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• 2007

A series of wet grinding experiments have been carried out using a stirred ball mill to systematically investigate consideration of grinding characteristics. The particle size distribution and median diameter of the grinding consumption power for a given grinding time were considered. Also, the effect of grinding aids on particle size and grinding consumption energy defined as the summation of grinding power was investigated. The grinding aids had influence on the smaller products size and decrease grinding consumption energy because the function of grinding aids were to be attribute to the prevention of agglomeration and ball and grinding chamber wall coating of sample powder. The grinding process seemed to be controlled by the force of agglomeration of the ground products. It was demonstrated that the particle size and grinding consumption energy could be more decreased by the addition of grinding aids.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.10a
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• pp.13-19
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• 1997

From the formation of the monodispersed silica particle which is a valuable for the industry by Sol-Gel process, the effects of the parameters participated in the process, the growth mechanism and the characteristics of silica particles for each rection conditions are investigated. To investigate about the formation of final silica particles, the suspension which performs the polymerization is reacted with molybdic acid, and the evolutions of TEOS and silica particle size are investigated in the reaction time ？ 새 the characteristics of molybdic acid with the suspension. From the results, a constant number of silica particle is formed at early reaction stage. Silica particles grow through the aggregation of smaller particles and nucleation is rate-limiting step for the growth of particles. In the conditions of this study, spherical silica particles are formed, [NH$_3$] and [$H_2O$] concentration increase the particle size but particle size decrease with [$H_2O$] concentration which is a certain above region. Average particle sizes are 187.4~483.3 nm and standard deviations in the average particle size are 1.7~2.9% with each experimental condition. From the BET results, specific surface area is 5.5~23.4 $m^2$/g and these values decrease with increase size. The average pore size is 50~70$\AA$.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.1
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• pp.77-83
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• 2010

The study was conducted to investigate the effect of particle size on the physicochemical properties of egg yolk-rice porridge. The pH of egg yolk-rice porridge was decreased when compared to that of the control, while the lightness and yellowness was increased as the rice particle size increased. The viscosity of whole particle egg yolk porridge was highest among the three porridges at $40^{\circ}C$. The protein content of the egg yolk-rice porridge was increased three-fold, when compared to that of the rice porridges. The total amino acid content of egg yolk-rice porridge was 1,500.6 mg/100 g, while that of rice was 1,147.5 mg/100 g. The Lys and Thr content of the amino acid content of egg yolk-rice porridge were also increased. Sensory evaluation results revealed that the half particle size rice egg yolk-rice porridge had the highest scores in color, taste and over-all preference. Based on these results, the half particle size egg yolk-porridge had good quality with respect to both the physicochemical and nutritional properties.

• Journal of ILASS-Korea
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• v.13 no.1
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• pp.42-50
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• 2008

In the present work, atomization characteristics of shear-thinning liquid slurry discharging from fan spray nozzles were studied experimentally for spray painting applications. The effects of solid particle size and concentration on the properties (especially on the viscosity) of suspensions and mean drop size were examined by using model fluids. In the range of low particle concentration (below 3 wt%), the fluid viscosity was primarily determined by the particle size. On the other hand, in the range of high particle concentration (higher than 10 wt%), the agglomeration phenomenon and the oil absorption capability of solid particles played major roles in determining the fluid viscosity. In the high concentration region, which most of the paints belong to, the fluid became more viscous and the shear thinning behavior appeared more prominent as the particle concentration was increased. In this region, mean drop size(SMD) decreased more rapidly with the increase of the injection pressure. Also, SMD became larger with the higher particle concentration and the larger particle size.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.55-60
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• 2010

Rockfill zones in CFRD consist typically of large granular materials, usually the maximum particle size up to several meters, which makes laboratory testing to determine the mechanical properties of rockfill difficult. Commonly, the design strength of the rockfills is obtained by scaling down the original rockfill materials and performing laboratory strength tests for the reduced size materials. The objective of the present study is to investigate the effect of particle size on the shear behavior and the strength for granular materials. A series of large-scale triaxial tests was conducted on large granular materials with the maximum particle size varying from 20 to 50mm. The test results showed that overall shear behaviors were similar between the samples with different particle sizes while there were slight differences in the magnitudes of the peak shear stress between the samples. In addition, a simulation of the granular material with the max. particle size of 20mm was performed using DEM code, $PFC^{2D}$, and compared with the test results. The deviatoric stress versus strain behaviors of experimental and numerical tests were found to be matched well up to the peak stress state.

• Journal of Powder Materials
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• v.28 no.1
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• pp.13-19
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• 2021

Bulk graphite is manufactured using graphite scrap as the filler and phenolic resin as the binder. Graphite scrap, which is the by-product of processing the final graphite product, is pulverized and sieved by particle size. The relationship between the density and porosity is analyzed by measuring the mechanical properties of bulk graphite. The filler materials are sieved into mean particle sizes of 10.62, 23.38, 54.09, 84.29, and 126.64 ㎛. The bulk graphite density using the filler powder with a particle size of 54.09 ㎛ is 1.38 g/㎤, which is the highest value in this study. The compressive strength tends to increase as the bulk graphite density increases. The highest compressive strength of 43.14 MPa is achieved with the 54.09 ㎛ powder. The highest flexural strength of 23.08 MPa is achieved using the 10.62 ㎛ powder, having the smallest average particle size. The compressive strength is affected by the density of bulk graphite, and the flexural strength is affected by the filler particle size of bulk graphite.