• Journal of Environmental Science International
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• v.19 no.3
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• pp.331-342
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• 2010

Aerosol physical properties have been measured at Pusan National University by using the 16-channel LPC(Laser Particle Counter), and particle characteristics have been examined for the period from Aug. 4 2007 to Dec. 30, 2008. Annual total average, seasonal average, and other averages of the meteorologically classified four categories such as Asian dust, precipitation, foggy, and clear days are respectively described here. Both annually and seasonally averaged number concentration show three peaks at the particle diameter of 0.3, 1.3, and $4{\mu}m$, respectively. However, the first peak for summer season tends to be shifted toward smaller size than other seasons, implying the strong fine particle generation. Meteorological condition shows strong contrast in aerosol concentrations. In Asian dust case, relatively lower number concentrations of fine particles (i.e., smaller than $0.5{\mu}m$) were predominant, while higher concentrations of coarse particles were found particularly for the size bigger than $0.5{\mu}m$. In precipitation day, number concentrations were decreased by approximately 30% due to the removal process of precipitation. Foggy day shows significantly higher concentrations for fine particles, implying the importance of the aerosol condensation process of micro-fine-particle growing to fine-particle. Finally the regressed particle size distribution function was fitted optimally with two log-normal distribution, and discussed the similarities and differences among four categorized cases of the Asian dust, precipitation, foggy, and clear days.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.75-79
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• 1989

The rheological properties of sugar and cocoa particle suspensions in cocoa butter under molten condition were analyzed with Haake rotationary viscometer. Both suspensions had yield value and showed rheopexy at low shear rate and thixotropy at high shear rate. Flow behaviors of the suspensions were analyzed with modified Casson model. Casson viscosity and yield value increased with increasing the concentration of sugar and cocoa particles. There was an obvious dependence of the Casson viscosity and yield value on the particle size distributions that was represented by the Sauter mean diameter of the particles. Casson viscosity and yield value of cocoa butter-sugar suspension increased with increasing the fineness of sugar particle crystal. With increasing the fineness of cocoa particle a decreasing Casson viscosity of cocoa butter-cocoa particle suspension was achieved, but the yield value did not change significantly with cocoa particle size. Therefore, it was predicted that the best rheological properties of chocolate could be obtained with the combination of coarse ground sugar $(d=36.30{\mu}m)$ and fine ground cocoa particle $(d=14.81{\mu}m)$ within the studied range.

• Journal of the Korea Institute of Building Construction
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• v.10 no.4
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• pp.11-20
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• 2010

This study carried out a Mock-up test to apply Low-heat Cement (CF) that is adjusted to a fineness of $3,000\;{\pm}\;200\;cm^2/g$ by substituting Coarse particle Cement (CC) and fly ash with ordinary Portland Cement (OPC), then applied it on-site. The result of the test is as follows. The Mock-up test showed that the amount of admixture in CF increased SP agent and AE agent slightly more compared to OPC, while temperature history showed that the highest temperature of CF was around $6{\sim}10^{\circ}C$ lower than that of OPC. Compressive strength in CF was low compared to that of OPC, but the strength width became narrow at the age of 28 days, which is not considered to be significant. In on-site application, slump, air content and chloride content all satisfied the target values, while the temperature history showed that the highest temperature in the center by each cast was about $34^{\circ}C$ in the first cast, $42^{\circ}C$ in the second cast, and $39^{\circ}C$ in the third cast. Compressive strength of specimen for strut management showed low value compared to standard curing, but its strength was reduced at the age of 28 days.

• Horticultural Science & Technology
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• v.17 no.3
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• pp.355-360
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• 1999

This study was carried out to investigate the effect of irrigation frequency, particle size and depth of perlite medium on the growth of Dendranthema grandiflorum (Ramat.) Kitamura 'Shuhouno-chikara' grown on recycling system. In Exp 1, the irrigation frequency (IF) was designed as 3 (IF3), 9 (IF9), and 18 (IF18) times a day. Fine and coarse particle size (PS) of perlite was used as a media, and depth of media (DM) was 15 and 10 cm contained in $34{\times}120{\times}15cm$ styrofoam bed. In Exp 2, the IF was 3 (IF3), 6 (IF6), and 9 (IF9) times a day with the same amount of nutrient solution. Fine and coarse PS were used, and DM was 15 and 7.5 cm. In this study, high IF and fine PS was favorable for plant growth. However, as the IF became frequent, difference of plant growth between fine and coarse PS became smaller. Also, shallow media showed little difference with deep media in plant growth. Thus, decreasing the amount of media was recommended to reduce the production cost.

• Journal of the Korean earth science society
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• v.23 no.6
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• pp.514-525
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• 2002

The analysis of heavy metals associated with both PM2.5 and PM10 fraction of aerosols was made from a northeast region of Seoul during the spring period of 2001. The mean concentrations of fine (PM2.5), coarse (PM10-PM2.5), and PM10 fraction were observed as 49.3${\pm}$29.2, 50.5${\pm}$35.0, and 95.5${\pm}$46.1 ${\mu}g$/m$^3$, respectively during this study period. According to the results of enrichment factor (EF) analysis between different particle fractions, major elements (including Fe, Ca, Na, and K) were found to exhibit EF values of less than 10. However, heavy metal components (like Zn and Pb) showed very high EF values. Comparison of fine/coarse (F/C) concentration ratio showed that Zn, Cr, Pb, and Ni have higher ratio values than others. The metallic composition of particles was also compared on both absolute and relative terms. The results of our analysis showed an evidence that the increase in the total metallic contents is prominent during the spring period due mostly to the Asian Dust event.

• Analytical Science and Technology
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• v.27 no.4
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• pp.213-222
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• 2014

The atmospheric aerosols of $PM_{10}$ and $PM_{2.5}$ were collected at Gosan site of Jeju Island during 2012- 2013. Their ionic and elemental species were analyzed in order to examine the composition variation of the haze aerosols in accordance with the pathway of air mass. The concentrations of $nss-SO_4{^{2-}}$, $NO_3{^-}$, and $NH_4{^+}$ increased 2.1~3.7 times in coarse particle and 3.1~6.5 times in fine particle modes, respectively, showing especially high $NO_3{^-}$ concentrations in fine particles during the haze days. The concentrations of S, Zn, Pb and K increased 3.0~5.6 times in coarse particles and 3.2~7.7 times in fine particles during the haze days, on the other hand Al, Fe, and Ca concentrations were high only in coarse particles. Due to the back trajectory analysis, the concentrations of $nss-SO_4{^{2-}}$ and $NO_3{^-}$ for haze days were high when the inflow pathway of air mass was from China, especially a high increase of $NO_3{^-}$ as through the south of China. The $NO_3{^-}/nss-SO_4{^{2-}}$ concentration ratio was relatively high in coarse mode as air mass inflow from China, but in fine mode it was high as air mass passing through the Korean peninsula.

• Asian Journal of Atmospheric Environment
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• v.11 no.2
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• pp.122-130
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• 2017

The main purpose of the study was to clarify the properties of individual particles collected at each behavior space of a factory worker. The samplings of size-segregated ($PM_{2.1-1.1}$ and $PM_{4.7-3.3}$) indoor particles were conducted at three different behavior spaces of a factory worker who is engaged in an auto parts manufacturing plant (i.e., his home, his work place in factory, and his favorite restaurant). Elemental specification (i.e., relative elemental content and distribution in and/or on individual particles) was performed by a micro-PIXE system. Every element detected from the coarse particulate matters of home was classified into three groups, i.e., a group of high net-counts (Na, Al, and Si), a group of intermediate net-counts (Mg, S, Cl, K, and Ca), and a group of minor trace elements (P, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb). The results of EF for $PM_{4.7-3.3}$ in home indicated that several heavy metals were generated from the sources within the house itself. An exceptional feature shown in the individual particles in workplace is that Cr, Mn, and Co were clearly detected in both fine and coarse particles. Cluster analysis suggested that the individual coarse particles ($PM_{4.7-3.3}$) collected at the indoor of factory were chemically heterogeneous and they modified with sea-salt, mineral, and artificially derived elements. The principal components in individual coarse particles collected at restaurant were sea-salt and mineral without mixing with harmful trace elements like chromium and manganese. Compared to the indoor fine particles of home and restaurant, many elements, especially, Cl, Na, Cr, Mn, Pb, and Zn showed overwhelmingly high net-counts in those of factory.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.3
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• pp.338-347
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• 2005

Horizontal-Flow Roughing Filtration (HRF) is one of altemative pretreatment methods e.g. prior to Slow Sand Filtration (SSF). However, some of its limitations are that the effluent quality drops drastically at higher turbidity (>200 NTU) and at higher filtration rate (>1 m/h). To overcome these drawbacks, we suggested Direct Horizontal-Flow Roughing Filtration (DHRF), which is a modified system of Horizontal-Flow Roughing (HRF) by addition of low dose of coagulant prior to filtration. In this study to optimize the DHRF configuration, a conceptual and mathematical model for the coarse compartment has been developed in analogy with multi-plate settlers. Data from simple column settling test can be used in the model to predict the filter performance. Furthermore, the model developed herein has been validated by successive experiments carried out. The conventional column settling test has been found to be an handy and useful to predict the performance of DHRF for different raw water characteristics (e.g. coagulated or uncoagulated water, different presence of organic matter, etc.) and different inital process conditions (e.g. coagulant dose, mixing time and intensity, etc.). An optimum filter design for the coarse compartment (grain size 20mm) has been found to be of 3 m/h filtration rate with filter length of 4-4.5 m.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.575-585
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• 2000

Mass and elemental dry deposition fluxes and ambient particle size distributions were measured using dry deposition plates, a cascade impactor. and a CPS(Coarse Particle Sampler), from July to November 1998 in Seoul. Korea. Primarily anthropogenic elemental fluxes (Cu, Mn, Ni, Pb, Zn) were on average one to two orders of magnitude lower than primarily crustal elements (Al, Ca). Complete total and elemental particle size distributions showed trimodal size distributions due to the peak in particles larger than $10{\mu}m$ in diameter. A multi-step model and the Sehmel-Hodgson model were used to calculate total and cumulative deposition fluxes. The result indicated that dry deposition fluxes were extremely sensitive to the mass of particles larger than $10{\mu}m$ in diameter due to their high dry deposition velocities. The result showed that particles larger than $10{\mu}m$ in diameter dominated atmospheric dry deposition. The modeled fluxes calculated using the measured atmospheric particle size distributions and modeled deposition velocities were compared to measured ones. In general, the measured mass and elemental fluxes agreed well with the modeled ones.

• Culinary science and hospitality research
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• v.18 no.3
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• pp.191-205
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• 2012

Due to a surplus of rice on the market, there has been a growing interest in developing better processed rice products, especially rice liquor or spirits which are popular and have a large market value. In this study, Takju was made with different varieties of rice and rice powder particle sizes, after which a taste survey was performed and measurements were taken on the characteristics of Takju including the temperature of the fermenting material, sugar content, alcohol content, acidity, amino acid types, colors, etc. The varieties of rice used in the study included Chucheong, Hiami and Anda. The temperature of the brew for each kind of Takju reached its highest point 48 hours after preparation. Differences among rice varieties were only apparent in the acidity and taste evaluations. The acidity was found to be highest with Anda, followed by Chuchoeng and Hiami. Chuchoeng had the highest taste evaluation scores. With regards to particle sizes, the alcohol content and acidity were found to be highest with coarse rice powder while ultra fine rice powder showed the highest fermenting temperature, sugar content, acidity, amino acid type, pH level, color and taste scores right after preparation. The results of this study suggest that among the kinds of Takju made from different rice varieties and particle sizes, the one made from Chucheong ultra fine rice powder is the most preferable over other variations.