• Korean Journal of Materials Research
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• v.22 no.8
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• pp.426-432
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• 2012

This study involves using nickel chloride solution as a raw material to produce nano-sized nickel oxide powder with average particle size below 50 nm by the spray pyrolysis reaction. The influence of the inflow speed of raw material solution on the properties of the produced powder is examined. When the inflow speed of the raw material solution is at 2 ml/min., the average particle size of the powder is 15~25 nm and the particle size distribution is relatively uniform. When the inflow speed of the solution increases to 10 ml/min., the average particle size of the powder increases to about 25 nm and the particle size distribution becomes much more uneven. When the inflow speed of the solution increases to 20 ml/min., the average particle size of the powder increases in comparison to the case in which the inflow speed of the solution was 10 ml/min. However, the particle size distribution is very uneven, showing various particle size distributions ranging from 10 nm to 70 nm. When the inflow speed of solution increases to 50 ml/min., the average particle size of the powder decreases in comparison to the case in which the inflow speed was 20 ml/min., and the particle size distribution shows more evenness. As the inflow speed of the solution increases from 2 ml/min. to 20 ml/min., the XRD peak intensities gradually increase, while the specific surface area decreases. When the inflow speed of solution increases to 50 ml/min., the XRD peak intensities rather decrease, while the specific surface area increases.

• Korean Journal of Materials Research
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• v.23 no.2
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• pp.81-88
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• 2013

In this study, using a tin chloride solution as the raw material, a nano-sized tin oxide powder with an average particle size below 50 nm is generated by a spray pyrolysis process. The properties of the tin oxide powder according to the nozzle tip size are examined. Along with an increase in the nozzle tip size from 1 mm to 5 mm, the generated particles that appear in the shape of droplets maintain an average particle size of 30 nm. When the nozzle tip size increases from 1 mm to 2 mm, the average size of the generated particles is around 80-100 nm, and the ratio of the independent particles with a compact surface structure increases significantly. When the nozzle tip size is at 3 mm, the majority of the generated particles maintain the droplet shape, the average size of the droplet-shaped particles increases remarkably compared to the cases of other nozzle tip sizes, and the particle size distribution also becomes extremely irregular. When the nozzle tip size is at 5 mm, the ratio of droplet-shaped particles decreases significantly and most of the generated particles are independent ones with incompact surface structures. Along with an increase in the nozzle tip size from 1 mm to 3 mm, the XRD peak intensity increases, whereas the specific surface area decreases greatly. When the nozzle tip size increases up to 5 mm, the XRD peak intensity decreases significantly, while the specific surface area increases remarkably.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.7
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• pp.107-115
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• 1996

The average distortio of the vector quantizer is calcualted using a probability function F of the input source for a given codebook. But, since the input source is unknown in geneal, using the sample vectors that is realized from a random vector having probability function F, a time-average opeation is employed so as to obtain an approximation of the average distortion. In this case the size of the smple set should be large so that the sample vectors represent true F reliably. The theoretical inspection about the approximation, however, is not perfomed rigorously. Thus one might use the time-average distortion without any verification of the approximation. In this paper, the convergence characteristics of the time-average distortions are theoretically investigated when the size of sample vectors or the size of codebook gets large. It has been revealed that if codebook size is large enough, then small sample set is enough to obtain the average distortion by approximatio of the calculated tiem-averaged distortion. Experimental results on synthetic data, which are supporting the analysis, are also provided and discussed.

• Journal of Korean Clinical Health Science
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• v.2 no.1
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• pp.17-23
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• 2014

Purpose. This study was to investigate the relationship between the palpebral fissure size and the exophthalmos in a population of Korean adult women subjects with normal eye status. Methods. From November 2012 to September 2013, The authors analyzed the morphological values in 73 Korean adults population. The test was performed using the Hertel exophthalmometer and verner califer. Analysis of subjects data were recorded using the spss version 20.0 a statistical program (IBM Co, Armonk, NY USA). Results. The average age of the 73 subjects (146 eyes) was (21.219+/-0.261)mm. the average value of palpebral fissure was (25.110+/-1.646)mm in width and (8.096+/-1.464)mm in height. The average value of exophthalmos was (15.002+/-1.922)mm. There was a significant relationship(P>0.05) in the average size between the width and height in palpebral fissure. Also, there was a significant relationship(P>0.05) in the average size between the palpebral fissure width and exophthalmos. On the other hand, there was a significant relationship(P>0.01) in the average size of palpebral fissure height and exophthalmos. Conclusions: In this study, these results suggested that the palpebral fissure and exophthalmos had a significant relationship in the average value of size in Korean adult women population.

• Journal of Powder Materials
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• v.11 no.3
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• pp.202-209
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• 2004

In this study, nano-sized powder of Ni-ferrite was fabricated by spray pyrolysis process using the Fe-Ni complex waste acid solution generated during the shadow mask processing. The average particle size of the produced powder was below 100 nm. The effects of the reaction temperature, the inlet speed of solution and the air pressure on the properties of powder were studied. As the reaction temperature increased from 80$0^{\circ}C$ to 110$0^{\circ}C$, the average particle size of the powder increased from 40 nm to 100 nm, the fraction of the Ni-ferrite phase was also on the rise, and the surface area of the powder was greatly reduced. As the inlet speed of solution increased from 2 cc/min. to 10 cc/min., the average particle size of the powder greatly increased, and the fraction of the Ni-ferrite phase was on the rise. As the inlet speed of solution increased to 100 cc/min., the average particle size of the powder decreased slightly and the distribution of the particle size appeared more irregular. Along with the increase of the inlet speed of solution more than 10 cc/min., the fraction of the Ni-ferrite phase was decreased. As the air pressure increased up to 1 $kg/cm^2, the average particle size of the powder and the fraction of the Ni-ferrite phase was almost constant. In case of 3 $kg/cm^2 air pressure, the average particle size of the powder and the fraction of the Ni-ferrite phase remarkably decreased.

• Journal of Korean Society on Water Environment
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• v.37 no.4
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• pp.286-295
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• 2021

The removal efficiency of road-deposited sediment (SDR) by road sweeping was analyzed by performing particle size analysis before and after road sweeping at four highways during May to December 2019. The SDR accounted for the largest proportion in the range of 250 to 850 ㎛ and the degree of its proportion had an effect on the particle size distribution curve. The particle size distribution of the collected sediments showed a similar distribution at all sites. Below 75 ㎛, the removal efficiency of SDR showed a constant value around 40%, but above 75 ㎛, it increased as the particle size increased. The removal efficiency was 82-90% (average 86%) for gravel, 66-93% (average 79%) for coarse sand, 35-92% (average 64%) for fine sand, 29-69% (average 44%) for very fine sand, 19-58% (average 40%) for silt loading, 10-59% (average 40%) for TSP, 13-57% (average 40%) for PM10, and 15-61% (average 38%) for PM2.5. SDR removal efficiency showed an average of 69% for the four highways. It was found that if the amount of SDR was less than 100 g/m², it was affected by the road surface condition and had a large regional deviation. As such, the amount of SDR and the removal efficiency increased. The fine particles, which have relatively low removal efficiency, contained a large amount of pollutants, which is an important factor in water and air pollution. Therefore, various measures to improve the removal efficiency of fine particles in SDR by road sweeping are needed.

• 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.

• Journal of the Korean Statistical Society
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• v.23 no.2
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• pp.403-420
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• 1994

An economic design of the $\bar{X}-R$ chart using variable sample size (VSS) scheme is proposed in this paper. In this design the sample size at each sampling time changes according to the values of the previous two sample statistics, sample mean and range. The VSS scheme uses large sample if the sample statistics appear near inside the control limits and smaller sample otherwise. The set of process parameters, such as the sampling interval, control limits and the sample sizes, are chosen to minimize the expected cost per hour. The efficiency of the VSS scheme is compared to the fixed sample size one for cases where there is multiple of assignable causes. Percent reductions of the expected cost in the VSS design are calculated for some given sets of cost parameters. It is shown that the VSS scheme improves the confidence of the procedure and performs statistically better in terms of the number of false alarms and the average time to signal, respectively.

• Korean Journal of Materials Research
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• v.21 no.7
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• pp.396-402
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• 2011

In this study, by using tin chloride solution as a raw material, a nano-sized tin oxide powder with an average particle size below 50 nm is generated by a spray pyrolysis process. The properties of the generated tin oxide powder depending on the inflow speed of the raw material solution are examined. When the inflow speed of the raw material solution is 2 ml/min, the majority of generated particles appear in the shape of independent polygons with average size above 80-100 nm, while droplet-shaped particles show an average size of approximately 30 nm. When the inflow speed is increased to 5 ml/min, the ratio of independent particles decreases, and the average particle size is approximately 80-100 nm. When the inflow speed is increased to 20 ml/min, the ratio of droplet-shaped particles increases, whereas the ratio of independent particles with average size of 80-100 nm decreases. When the inflow speed is increased to 100 ml/min, the average size of the generated particles is around 30-40 nm, and most of them maintain a droplet shape. With a rise of inflow speed from 2 ml/min to 5 ml/min, a slight increase of the XRD peak intensity and a minor decrease of specific surface area are observed. When the inflow speed is increased to 20 ml/min, the XRD peak intensity falls dramatically, although a significant rise of specific surface area is observed. When the inflow speed is increased to 100 ml/min, the XRD peak intensity further decreases, while the specific surface area increases.

• Journal of Species Research
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• v.12 no.3
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• pp.203-211
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• 2023

Five ciliate species of Euplotes were isolated from fresh and coastal water during a sampling survey to identify unrecorded ciliates in South Korea. Their morphology was investigated using live observation, protargol and "wet" silver nitrate staining methods. Brief descriptions and microphotographs of each species and a comparison with related species are provided. Euplotes focardii is characterized by an average size of 65×47 ㎛ after protargol impregnation, 6 dorsal and 3 ventral ridges and dorsal argyrome pattern of double-eurystomus type. Euplotes nobilii shows an average size of 34×20 ㎛ after protargol staining, 6 dorsal and 3 ventral ridges and dorsal argyrome pattern of double-patella type. Euplotes octocarinatus, the only freshwater species described in the present study, is characterized by an average size of 66×46 ㎛ after protargol impregnation, 6 dorsal and 3 ventral ridges and dorsal argyrome pattern of double-patella type. Euplotes petzi has an average size of 43×30 ㎛ after protargol staining, a macronucleus hook-shaped and dorsal argyrome pattern in double-patella type. Euplotes raikovi is characterized by an average size of 40×24 ㎛ after protargol staining, 6 dorsal and 3 ventral ridges and dorsal argyrome pattern of double-patella type.