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

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.38 no.3 s.116
• /
• pp.7-12
• /
• 2006

The pore structure of paper was 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 the above parameters. It was also found that the change of reflectivity of paper was greatly dependent on the pore structure, such as average pore size, pore size distribution and porosity. The average pore size was decreased with addition of HwBKP, but the smallest average pore size was obtained from the addition of 80% 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

• Korean Journal of Materials Research
• /
• v.23 no.9
• /
• pp.489-494
• /
• 2013

In this study, by using nickel chloride solution as a raw material, a nano-sized nickel oxide powder with an average particle size below 50 nm was produced by spray pyrolysis reaction. A spray pyrolysis system was specially designed and built for this study. The influence of nozzle tip size on the properties of the produced powder was examined. When the nozzle tip size was 1 mm, the particle size distribution was more uniform than when other nozzle tip sizes were used and the average particle size of the powder was about 15 nm. When the nozzle tip size increases to 2 mm, the average particle size increases to roughly 20 nm, and the particle size distribution becomes more uneven. When the tip size increases to 3 mm, particles with an average size of 25 nm and equal to or less than 10 nm coexist and the particle size distribution becomes much more uneven. When the tip size increases to 5 mm, large particles with average size of 50 nm partially exist, mostly consisting of minute particles with average sizes in the range of 15~25 nm. When the tip size increases from 1 mm to 2 mm, the XRD peak intensities greatly increase while the specific surface area decreases. When the tip size increases to 3 mm, the XRD peak intensities decrease while the specific surface area increases. When the tip size increases to 5 mm, the XRD peak intensities increase again while the specific surface area decreases.

• Korean Journal of Materials Research
• /
• v.21 no.12
• /
• pp.690-696
• /
• 2011

In this study, nano-sized tin oxide powder with an average particle size of below 50 nm is prepared by the spray pyrolysis process. The influence of air pressure on the properties of the generated powder is examined. Along with the rise of air pressure from $0.1kg/cm^2$ to $3kg/cm^2$, the average size of the droplet-shaped particles decreases, while the particle size distribution becomes more regular. When the air pressure increases from $0.1kg/cm^2$ to $1kg/cm^2$, the average size of the dropletshaped particles, which is around 30-50 nm, shows hardly any change. When the air pressure increases up to $3kg/cm^2$, the average size of the droplet-shaped particles decreases to 30 nm. For the independent generated particles, when the air pressure is at $0.1kg/cm^2$, the average particle size is approximately 100 nm; when the air pressure increases up to $0.5kg/m^2$, the average particle size becomes more than 100 nm, and the surface structure becomes more compact; when the air pressure increases up to $1kg/cm^2$, the surface structure is almost the same as in the case of $0.5kg/cm^2$, and the average particle size is around 80- 100 nm; when the air pressure increases up to $3kg/cm^2$, the surface structure becomes incompact compared to the cases of other air pressures, and the average particle size is around 80-100 nm. Along with the rise of air pressure from $0.1kg/cm^2$ to $0.5kg/cm^2$, the XRD peak intensity slightly decreases, and the specific surface area increases. When the air pressure increases up to $1kg/cm^2$ and $3kg/cm^2$, the XRD peak intensity increases, while the specific surface area also increases.

• Journal of Korean Academy of Nursing
• /
• v.28 no.4
• /
• pp.941-957
• /
• 1998

The purpose of this study was to use meta-analysis to analyze result of 17 studies which investigated the effects of integrated programs, and 11 studies which examined the effects of exercise programs on pain, depression, and disability. The 28 studies analyzed in this work were selected from the following sources. MEDLINE Search, bibliographies of related studies, main academic journals of nursing in Korea, and journals on arthritis issues. For the analysis of the data, homogeniety of effect sizes which were calculated based on data in the 28 studies was tested and its average effect size was computed by using meta analysis software package which was developed by Song(1992, 1998). The results can be summarized as follows : 1) Homogeneity tests were conducted on integrated programs on pain. In the prelimiary homogeneity tests on effect size of all 17 studies, no homogeneity was found. When homogeneity tests on the effect size of the remaining 15 studies were performed, excluding two studies which had extremely larger effect size compared to other studies, the 15 studies were found to be homogeneous(Q=16.38, p=.23). The obtained average effect size, D(Mean Standardized Difference Between Means), was .25. When homogeneity tests on effect size on pain was conducted for the excercise programs, effect size for all nine studies were found to be homogeneous (Q=7.42, p=.49) and the average effect size D=.30. Therefore, Hypothesis 1 was rejected from the results, that an average effect size of the integrated programs on pain was not significantely different from that of the exercise programs on pain. 2) Since only two studies investigated the effect of exercise programs on depression, comparison between the average effect size of integrated programs and that of exercise programs on depression could not be conducted, and hypothesis 2 could not be tested. Thereby, only the average effect size of integrated programs on depression was obtained. Eight studies were tested to be positive on the homogeneity of effect sizes(Q=18.31, p=.02) at $\alpha$<.01 and its average effect size was D=.11. 3) For the analysis of integrated program on disability, 13 studies, except for four which had an extremely large effect size compared to the others were found to be homogeneous at $\alpha$<.01 (Q=22.30, p=.04) and the average effect size on disability was D=.16. For analysis of the exercize programs on disability, eight studies, except for one which had an extremely large effect size compared to others, were found to be homo geneous(Q=7.87, p=.34) and the average effect size on disability was D=.60. Therefore, Hypothesis 3 was accepted from the results that an average effect size of exercise programs on disability was significantly larger than that of integrated programs on disability.

• Journal of Powder Materials
• /
• v.11 no.6 s.47
• /
• pp.493-502
• /
• 2004

In this study, nano-sized indium oxide powder with the average particle size below 100 nm is fab-ricated from the indium chloride solution by the spray pyrolysis process. The effects of the reaction temperature, the concentration of raw material solution and the inlet speed of solution on the properties of powder were studied. As the reaction temperature increased from 850 to $1000^{\circ}C$, the average particle size of produced powder increased from 30 to 100 nm, and microstructure became more solid, the particle size distribution was more irregular, the intensity of a XRD peak increased and specific surface area decreased. As the indium concentration of the raw material solution increased from 40 to 350 g/l, the average particle size of the powder gradually increased from 20 to 60 nm, yet the particle size distribution appeared more irregular, the intensity of a XRD peak increased and spe-cific surface area decreased. As the inlet speed of solution increased from 2 to 5 cc/min., the average particle size of the powder decreased and the particle size distribution became more homogeneous. In case of the inlet speed of 10 cc/min, the average particle size was larger and the particle size distribution was much irregular compared with the inlet speed of 5 cc/min. As the inlet speed of solution was 50 cc/min, the average particle size was smaller and microstructure of the powder was less solid compared with the inlet speed of 10 cc/min. The intensity of a XRD peak and the variation of specific area of the powder had the same tendency with the variation of the average par-ticle size.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.29 no.1
• /
• pp.7-12
• /
• 1997

This study was intended to investigate the proper shape and size of calcium carbonate for the improvement of paper properties and its end use performance. We loaded calcium carbonate of various shapes and size in the handsheet and measured their physical and optical properties. Results obtained from the study are summarized as follows : 1. Due to different particle shapes and sizes, precipitated calcium carbonate (PCC) contributed greater to bulk improvement than ground calcium carbonate (GCC). Scalenohedral form of PCC produced the bulkiest sheet, GCC made the sheet bulkier as average particle size increases. 2. Tensile strength increased as average particle size was increasing. GCC kept tensile strength more effectively than PCC. The effect of particle size on tensile strength was much more pronounced as filler addition level was increasing. 3. Over the average particle size of 6.99$\mu$m, GCC gave much higher burst strength and internal bond than PCC did. In the filler levels of 20% and 30%, GCC by using bigger size fillers showed 50~100% improvement in some cases than PCC at the same filler content. 4. Tear strength increased as average particle size was increasing. At the filler level of 30%, PCC decreased tear greatly. 5. Over the average particle size of 13.56$\mu$m, GCC kept bending stiffness greater than PCC. Due to its shape, Scalenohedral form of PCC showed higher stiffness than others at the same particle size. 6. Cubic and acicular form of PCC improved light scattering coefficient very effectively. Light scattering coefficient of GCC decreased as average particle size increased. 7. Both of particle shape and size of filler were important factor in developing optical properties and bending stiffness. Particle size was the only important factor in developing other strength properties

• Journal of Industrial Technology
• /
• v.19
• /
• pp.301-312
• /
• 1999

The purpose of this paper is to study the effects of container size with multi-stage and multi-item on average inventory and customer service level in Kanban systems. We use the different distributions of demand and interarrival time for each item to show that we had better to change the container size depending on different type of item for this simulation study. The small lot size can be used for container size of a single item if there is no setup time. The container size should be identical with average order size as setup time increases. The fill rate increases if the container size is large with multi-item. However, it is difficult to establish the effective container size because the effects of the container size on the order queue time are not clear. It is suitable to use the average order size as the container size for each item if the variance of demand and interarrival time of each item is relatively small. It is effective to sue the average container size if the variance of them is relatively large.

• Journal of the Korean Dietetic Association
• /
• v.4 no.2
• /
• pp.132-144
• /
• 1998

The purpose of this study is setting proper portion by consumed size of food and food preference and then reducing plate wasts in school lunch. The survey was conducted from Oct. 21 to Nov. 22, 1996 through the practical measurement and questionnaires. The subjects were 43 students of 1 elementary school. The results of this survey was as follows : 1. Average consumption size of cooked rice was 115g. Average consumption size of one course dishes was 209g. The soup & pot stewes showed lower consumption rate than the other kind of foods. Average consumption size of fresh & boiled salad was 23.4g Average consumption size of stir fries was 55g. Average consumption size of steams & stewes was 42g. Most grill & fried foods showed high consumption rate compared to most of the other foods. Average consumption size of kimchies was 10.6g. The most of given desserts except apple were all consumed. 2. There was significant correlation between food preference and consumption rate for total food items. 3. Response of satisfaction about serving size of most of given foods except fresh & boiled salads, soup & pot stewes and kimchies were "moderate". 4. Visual estimation was greater than physical estimation for most of given foods. Proper portion of foods per person by results were setted as follows :

• Journal of the Korean Society for Heat Treatment
• /
• v.12 no.2
• /
• pp.157-165
• /
• 1999

Grain size of steels is one of the most important parameters which influence yield strength and fracture toughness. Ultrasonic wave propagating in polycrystalline materials is mostly attenuated by scattering at grain boundary. Effect of ultrasonic attenuation on average ferrite grain size of carbon steels with tensile strength $40{\sim}60kgf/mm^2$ consisting of multi phases such as ferrite + pearlite and ferrite + pearlite + bainite was evaluated. The attenuation of these steels rapidly increased with average ferrite grain diameter. Average ferrite grain diameter ($D_{av}$, ${\mu}m$) could be expressed as $1.79+22.97*a^{1/2.03}$, where a is attenuation with unit of nepers/cm. From this study, it was confirmed that nondestructive ultrasonic method could be used in measuring average ferrite grain size indirectly.