• Particle and aerosol research
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• v.18 no.3
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• pp.61-68
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• 2022

In this study, a fluidized bed particle generator was developed to generate an aerosol without supply of compressed air and to increase portability. It was assumed that the mixing ratio of the test particles and beads, the input amount, and the air flow rate supplied to the generator would have effect on the aerosol generation characteristics. The product of these three parameters was set as a characteristic parameter and particle generation characteristics according to the change of the characteristic parameter were observed. As a result, it was confirmed that the input amount of test particles and beads was not suitable as a characteristic parameter and a characteristic parameter expressed as a product of the mass mixing ratio and the air flowrate was newly defined. When the new characteristic parameter is applied, it can be confirmed that the total amount of particles generated from the particle generator is a function of the characteristic parameter. As a result of measuring the amount of particle generation by adjusting the characteristic parameter, it was confirmed that the performance required for the test particle generator for the field inspection equipment of PM-2.5 sensors could be satisfied.

• Journal of the Korean earth science society
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• v.25 no.6
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• pp.428-442
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• 2004

Dustfall samples were collected by the modified American dust jar (bulk type) at 5 sampling sites in the Nakdong river area from lune 2002 to May 2003. Nineteen chemical species (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Si, V, Zn, $Cl^-$, $NO_3^-$, $SO_4^{2-}$, and $NH_4^+$) were analyzed via the combination of ICP/AES, AAS, IC and UV. The purposes of this study were to qualitatively evaluate the chemical composition of dustfalls by examining their regional and seasonal distribution patterns. Computation of the enrichment factor showed that well-defined anthropogenic sources, particularly in Pb were found in the order Gamjeondong (industrial area), Wondong, Silla University, Samrangiin and Mulgum. The seasonal mean of soil contribution showed its highest value (16.3%) during the winter with an annual mean of 11.2%. The concentration ratio of [$SO_4^{2-}/NO_3^-$] was found to be highest (5.12) during the winter, while the lowest ratio value (3.30) was seen during the all. fall, Also regional equivalent ratios of [$SO_4^{2-}/NO_3^-$] were found in the order: Silla University (6.78), Gamjeondong (4.98), Mulgum (3.95), Wondong (3.85), and Samrangjin (2.87). Seasonal distribution of water soluble components for total dustfall were found in the order: spring (71.6%), summer (61.2%), fall (49.2%) and winter (48.6%) with a mean ratio of 57.6%. Regional contribution of sea salts of water soluble ions were found in the order: Silla university (34.5%), Gamjeondong (28.3%), Wondong (17.3%), Samrangiin (17.2%) and Mulgum (13.8%), the total mean contribution rate was 22.1%. As for the chemical composition of dustftll on the lower Nakdong river, there is a decreased influence of sea salt and artificial anthropogenic sources and increased influence of soil particle inland. Also, the total amount of deposition on the lower Nakdong river has decreased, with the river's surface serving as a confounding factor in resuspending dusts.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.50-54
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• 2014

Evaluation of the possible or probable effects of environmental conditions which are temperature, radiation, dust as well as other possibilities in terms of meteoroids, seismicity, and no global magnetic field has been carried out for wireless communications on the lunar surface in this paper. The results considered in this paper can be utilized as a basic information on making efficient use of the design for wireless communications system in Korean lunar exploration project.

• Journal of the Korean Society of Visualization
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• v.19 no.3
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• pp.130-135
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• 2021

Water vapor has received worldwide large attention due to its broad technological implications ranged from resource production and environmental remediation. Especially, one of the typical areas where the water vapor is important is the removal of PM (particulate matter) which causes a critical hazard to human health. However, most vapor-based PM removal methods are limited in removing PM2.5 by using relatively large water droplets and consume large energy. Here, we propose a superhydrophilic thermally-insulated macroporous membrane to generate steam flow. The water vapor directly captures PM with steam flow and hygroscopic characteristic of PM. The steam, the cluster of water vapor, from the membrane gives rise to high removal efficiencies compared to those of the control case without light illumination. To reveal PM removal mechanism, the steam flow and PM were quantitatively analyzed using PIV measurement. The proposed steam generator could be utilized as an economical and ecofriendly platform for effective PM removal at a fairly low cost in a sustainable, energy-free, and harmless-to-human manner.

• Journal of Animal Environmental Science
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• v.11 no.3
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• pp.197-206
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• 2005

This study was carried out to investigate the concentration and characteristics of dust originating from windowless broiler building in each season. 12.0m width and 46m tenth with side wall height of 3.0m was investigated and capacity was 12,800 birds at a stock density of 23.2 birds per square meter. Dust concentrations in terms of total suspended particles (TSP), and particulate matter of sizes $10{\mu}m(PM10),\;2.5{\mu}m (PM2.5),\;and\;1{\mu}m(PM1)$ were measured at 30-minute intervals. On the basis of broiler age, the average dust concentration in summer in TSP as follows: 1,229 904.5 558.8 and $1,053{\mu}g/m^3$ on the broilers' first to fourth week of age, respectively. But during winter, the average dust concentration showed an increasing pattern, as follows: 465.4, 1,401, 4,497, 5,097 and $6,873{\mu}g/m^3$ on the broilers' first to fifth week of age, respectively. The maximum dust concentration of $11,132{\mu}g/m^3$ was observed on the fifth week. On a daily basis, the maximum dust concentration during summer was detected in early morning, and the minimum in the afternoon. The aerial dust particle size of $0.05\~0.35{\mu}m$ was the highest in number. But on volume basis, particle size of 16~99 un had the largest percentage in the broiler house. Crude protein of the dust $(42.8\~65.2\%)$, on dry matter basis, was higher than that $(20.5\~24.5\%)$ fed to the broilers. Heavy metal concentration of the dust also had high levels compared with that of the feed.

• Journal of Wetlands Research
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• v.11 no.2
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• pp.47-54
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• 2009

This study was conducted to consider the characteristics of PM10(particulate matter with aerodynamic diameters less than 10 ${\mu}m$) concentration according to land-use in Busan coastal area. Fine particle is affected by emissions, geographical conditions and meteorological factors. In case industrial area, Gamjeondong(inland) PM10 concentration was higher than Noksandong(seashore) at all season except for Summer. Primary peak at Gamjeondong cleared than Noksandong in Fall and Winter. In case green area, Daejeodong(inland) PM10 concentration was higher than Dongsamdong(seashore) at all seasons. In case commercial area, primary peak occurrence time at Jeonpodong lagged one hour according to season and diurnal change of PM10 concentration at Gwangbokdong was higher than Jeonpodong in Spring. In case residential area, high PM10 concentration(80~90 ${\mu}g/m^3$) lasted for six hours during the daytime in Spring at Deogcheondong and Yongsuri(inland).

• Journal of the Korean Society for Railway
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• v.14 no.4
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• pp.313-319
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• 2011

In a modern society, various type of transportation modes are utilized, among them the subway system is the one of the main transportation mode which more than 7.21 million people ride a day in Seoul. Due to the increased interests on the indoor air quality (IAQ) of underground facilities, public concerns on IAQ of subway system are increasing also. Platform screen door (PSD) recently installed at the whole stations of Seoul subway and tunnel washing-out appeared to be effective in reducing particulate matters in the platform and tunnel. However there has not been any attempt to improve IAQ of subway cabin inside. Most technologies for removing airborne particulate matters are known to be difficult to adopt on the subway cabin due to the problem of maintenance cost. Therefore, the object of this study is a practical development of cabin air cleaning system which can reduce the concentration of airborne particles and harmful gases at the same time. In this paper, we focused on the development of particle removing system utilizing a roll-filter for increasing operating time of air filter. The prototype of system was designed and manufactured based on the numerical prediction results. For rollfilter device, 5 candidate filter materials were tested in point of particle collection efficiency and pressure drop. It was found that the electrically charged filter material showed the highest performance among them.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.8
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• pp.739-746
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• 2010

The purposes of this study are 1) to develop an advanced chamber system within ${\pm}10%$ of air velocity at the particulate matter (PM) collection area, 2) to research theoretical characteristics of PM10 and PM2.5 samplers, 3) to assess the performance characteristics of PM10 and PM2.5 samplers through chamber experiments. The total six one-hour experiments were conducted using the cornstarch with an mass median aerodynamic diameter (MMAD) of $20\;{\mu}m$ and an geometric standard deviation of 2.0 at the two different air velocity conditions of 0.67 m/s and 2.15 m/s in the chamber. The aerosol samplers used in the present study are one APM PM10 and one PM2.5 samplers accordance with the US federal reference methods and specially designed three mini-volume aerosol samplers (two for PM10 and one for PM2.5). The overall results indicate that PM10 and PM2.5 mini-volume samplers need correction factors of 0.25 and 0.39 respectively when APM PM samplers considered as reference samplers and there is significant difference between two mini-volume aerosol samplers when a two-way analysis of variance is tested using the measured PM10 mass concentrations. The PM10 and PM2.5 samplers with the cutpoints and slopes (PM10: $10{\pm}0.5\;{\mu}m$ and $1.5{\pm}0.1$, PM2.5: $2.5{\pm}0.2\;{\mu}m$ and $1.3{\pm}0.03$) theoretically collect the ranges of 86~114% and 64~152% considering the cornstarch characteristics used in this research. Furthermore, the calculated mass concentrations of PM samplers are higher than the ideal mass concentrations when the airborne MMADs for the cornstarch used are smaller than the cutpoints of PM samplers and the PM samplers collected less PM in another case. The chamber experiment also showed that PM10 and PM2.5 samplers had the bigger collection ranges of 37~158% and 55~149% than the theocratical calculated mass concentration ranges and the relatively similar mass concentration ranges were measured at the air velocity of 2.15 m/s comparing with the 0.67 m/s.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.268-274
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• 2010

Emission of heavy metals as hazardous air pollutants has been focused with tightening regulatory limits due to their hazardousness. Measurements and characteristic investigations of heavy metals emitted from a commercial power plant burning anthracite coal have been carried out. The plant consists of a circulating fluidized bed combustor, a cyclone, a boiler and an electrostatic precipitator(ESP) in series. Dust and gaseous samples were collected to measure main heavy metals including gaseous mercury before ESP and at stack. Dust emissions as total particulate matter (TPM), PM-10 and PM-2.5 at inlet of ESP were very high with 23,274, 9,555 and $7,790mg/Sm^3$, respectively, as expected, which is much higher than those from pulverized coal power plants. However TPM at stack was less than $0.16mg/Sm^3$, due to high dust removal efficiency by ESP. Similarly heavy metals emission showed high collection efficiency across ESP. From particle size distribution and metal enrichment in sizes, several metal concentrations could be correlated with particle size showing more enrichment in smaller particles. Mercury unlike other solid metals behaved differently by emitting as gaseous state due to high volatility. Removal of mercury was quite less than other metals due to it's volatility, which was 68% only. Across ESP, speciation change of mercury from elemental to oxidized was clearly shown so that elemental mercury was half of total mercury at stack unlike other coal power plants which equipped wet a scrubber.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.5
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• pp.512-517
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• 2014

This paper describes the development of new sweeping machine based on Cyclone Technology, which maintains constant suction power and uses it in a industrial applications as a method for dust removed from grinding work. The performance of a cyclone separator is determined by the turbulence characteristics and particle-particle interaction. To achieve this goal, we design cyclone technology based dust separator for sweeping machine has been proposed as a system which is suitable to work utilizing dust suction alternative to conventional manual system. and Numerical analysis with computational fluid dynamics(CFD) was carried out to investigate the working fluid that flow into cyclone dust separator in order to design optimal structure of the sweeping machine. The validation of cyclone model with CFD is carried out by comparing with experimental results.