• Journal of Environmental Health Sciences
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• v.17 no.2
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• pp.22-26
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• 1991

Authors investigated the particulate size distribution in work environment of Banwol and Changwon industrial complex. Size distributions of particles exposured to workers in welding and in grinding process were evaluated by ambient cascade impactors. Respirable matter fractions were calculated from the size distribution data by the respirable particle mass of the ACGIH criteria.

• Journal of ILASS-Korea
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• v.1 no.1
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• pp.44-54
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• 1996

A theoretical and experimental study was carried out on the prediction of drop size distribution of the pressure swirl atomizer. Drop size distribution was obtained by using maximum entropy formal ism. Several constraints in the form of the definition of mean diameter were used in this formulation in order to avoid the difficulties of the estimating source terms. In this study $D_{10}$ was only introduced into the formulation as a constraint. A drop size obtained by using linear Kelvin-Helmholtz instability theory was considered as an unknown characteristic length scale. As a result, the calculated drop size was agreed well with measured mean diameter, particularly with $D_{32}$. The predicted drop size distribution was agreed welt with experimental data measured wi th Malvern 2600.

• Journal of the Korean Ceramic Society
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• v.23 no.4
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• pp.35-40
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• 1986

The production process of a fine size fraction of Korean kaolin by ball milling is studied in this paper by analyzing the size distribution the size distribution of products with the Rosin-rammle formular and the rate process of cumulative size fractions with Alyavdin-Chujyo's formular. The size distribution is found to be divided in three regions a coarser part influenced by feed size an intermediate part where the size distribution shows a clear straight line relationship on Rosin-Rammler chart and the finest part with the ultimate limit of fineness by ball milling. Alyavdin-Chujyo's relationship is found to be valid over a very wide range of milling conditions. For different feed sizes the Alyavdin-Chujyo's relationship gives a group of straight lines with a common intersection point which can be defined as the limiting point of the persistent component region.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.199-206
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• 2003

Particle-size distribution in soils is one of the most fundamental physical properties of soils. One of the latest developments in the study of particle-size distributions has focused on the use of fractal theories. In this study, the fragmentation fractals were used for determining the characteristics of the particle-size distribution curve. It was shown that the mass-size distribution method was more practical than the cumulative number-size distribution method. From the co-relation between fractal dimensions($D_{tot}$) and the coefficient of uniformity($C_{u}$), there was a sharp increase in fractal dimensions for $C_{u}$<4, but fractal dimension converged the single value for $D_{u}$$\geq$6. Fractal dimensions were affected by small sized particles for $C_{c}$$\geq$3 and large sized particles for $C_{c}$/<3. As a result of the analysis of the influence of the effective size($D_{10}$), it was observed that the changes of $D_{tot}$/ were nominal beyond the effective size.

• Journal of Powder Materials
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• v.10 no.4
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• pp.262-269
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• 2003

Nano-sized Ni-ferrite powder was fabricated by spray pyrolysis process using the waste solution resulting from shadow mask processing. The average particle size of the powder was below 100 nm. The effects of the concentration of raw material solution, the nozzle tip size and air pressure on the properties of powder were studied. As the concentration increased, the average particle size of the powder gradually increased and its specific surface area decreased, but size distribution was much wider and the fraction of the Ni-ferrite phase greatly increased as the concentration increasing. As the nozzle tip size increased from 1 mm to 2 mm, the average particle size of the powder decreased. In case of 3 mm nozzle tip size, the average particle size of the powder increased slightly. On the other hand, in case of 5 mm nozzle tip size, average particle size of the powder decreased. Size distribution of the powder was unhomogeneous, and the fraction of the Ni-ferrite phase decreased as the nozzle tip size increasing. As air pressure increased up to 1 kg/$cm^2$, the average particle size of the powder decreased slightly, on the other hand, the fraction of the Ni-ferrite phase was almost constant. In case of 3kg/$cm^2$ air pressure, average particle size of the powder and the fraction of the Ni-ferrite phase remarkably decreased, but size distribution was narrow.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.479-484
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• 2006

The pore structures of paper were modified by the application of the blending of pulp, refining, and filler particle size and ash content. It was conformed that the reflectivity of paper can be modified by the combination of above parameters. It was also found that the modifications of reflectivity of paper were very close relation with pore structure, such as average pore size, pore size distribution and porosity. The average pore size was decreased with addition of HwBKP, but showed smaller particle size than those made from 100% HwBKP. Refining of pulp decreased both average pore size and the reflectivity of paper. The pore size distribution of filled paper can be varied by the combination of filler particle size and ash content.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.618-629
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• 1991

The purpose of this experiment is to understand the distribution of coal particles inside CWM droplet which is believed to be a very important factor controlling the flame stability. CWM slurry is atomized by an air assisted twin fluid nozzle. An experimental rig is designed and fabricated. The mean size of coal particle distribution in CWM slurry, atomizing air pressure, coal particle loading in slurry and sampling position inside spray are main experimental variables. The atomized CWM droplets are sampled on the thin white layer of magnesium oxide by the emergency sampling shutter. The sampled coal particles on magnesium oxide layers are collected into test tubes and dispersed completely by Ultra-Sonicator. The size distribution of coal particles inside droplets are measured by Coulter Counter. The presence of coal particle inside the impressions of droplets on magnesium oxide layer are investigated by photo technique. There are quite many droplets which do not have any coal particles. Those are just water droplets, not CWM droplets. The population ratio of droplets without coal particles to toal number of droplets is strongly affected by the mean size of coal particle distribution in slurry and this ration becomes bigger number as the mean size of coal particles be larger. The size distribution of coal particles inside CWM droplets is not even and depends on the size of droplet. Experimental results show that the larger CWM droplets has droplets has bigger mean value of particle size distribution. This trend becomes more evident as the atomizing air pressure is raised and the mean size of coal particles in CWM slurry is bigger. That is, the distribution of coal particles inside CWM dropolets is very much affected by the atomizing air pressure and the mean size of pulverized coal particles in CWM slurry.

• Communications of the Korean Mathematical Society
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• v.10 no.2
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• pp.419-438
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• 1995

We investigate a tansient diffusion approximation of queue size distribution in $M^{X}/G^{Y}/c$ system using the diffusion process with elementary return boundary. We choose an appropriate diffusion process which approxiamtes the queue size in the system and derive the transient solution of Kolmogorov forward equation of the diffusion process. We derive an approximation formula for the transient queue size distribution and mean queue size, and then obtain the stationary solution from the transient solution. Accuracy evalution is presented by comparing approximation results for the mean queue size with the exact results or simulation results numerically.

• Journal of the Korean Geotechnical Society
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• v.38 no.3
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• pp.27-34
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• 2022

Since water flow in the ground depends on the pore structure composed of soil grains, equations to predict the hydraulic properties based on the grain size have low accuracy. This paper presents a methodology to compute constriction-pore size distribution by Silveria's method and estimate saturated and unsaturated hydraulic properties of soils. Well-graded soil shows a uni-modal pore size distribution, and poor-graded soil does a bimodal distribution. Among theoretical models for saturated hydraulic conductivity using pore size distribution, Marshall model is well-matched with experimental results. Model formulas for soil-water characteristic curves and unsaturated hydraulic conductivity using the pore size distribution are proposed for hydraulic analysis of unsaturated soil. Continuous research is needed to select a model suitable to estimate hydraulic properties by applying the developed model formulas to various soils.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.13 no.1
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• pp.55-72
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• 2009

A misclassified size-biased modified power series distribution (MSBMPSD) where some of the observations corresponding to x = c + 1 are misclassified as x = c with probability $\alpha$, is defined. We obtain its recurrence relations among the raw moments, the central moments and the factorial moments. Discussion of the effect of the misclassification on the variance is considered. To illustrate the situation under consideration some of its particular cases like the size-biased generalized negative binomial (SBGNB), the size-biased generalized Poisson (SBGP) and sizebiased Borel distributions are included. Finally, an example is presented for the size-biased generalized Poisson distribution to illustrate the results.