• Korean Journal of Mineralogy and Petrology
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• v.35 no.4
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• pp.397-407
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• 2022

Mineralogical analysis of the bedrock of the Gobi Desert in southern Mongolia, the source of Asian dust, was conducted to trace the geological origin of the constituent minerals of Asian dust. The bedrock of the source of Asian dust consists of Paleozoic volcanics and volcaniclastic sedimentary rocks, Paleozoic granitic rocks, and Mesozoic sedimentary rocks. Paleozoic volcanics and volcaniclastic sediments lithified compactly, underwent greenschist metamorphism, and deformed to form mountain ranges. Mesozoic sedimentary rocks fill the basin between the mountain ranges of Paleozoic strata. In comparison to Paleozoic volcanic and sedimentary rocks, Mesozoic sedimentary rocks have lower contents of chlorite and plagioclase, but high contents of clay minerals including interstratified illite-smectite, smectite, and kaolinite. Paleozoic granites characteristically contain amphibole and biotite. Compared with the mineral composition of bedrock in source, Asian dust is a mixture of detrital particles originating from Paleozoic and Mesozoic bedrocks. However, the mineral composition of Mesozoic sedimentary rocks is closer to that of Asian dust. Less lithified Mesozoic sedimentary rocks easily disintegrated to form silty soils which are deflated to form Asian dust.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.42-45
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• 2006

A new and reusable energy source is water-treatment sludges. There is a significant need for understanding the characteristics of sludge combustion related to improving efficiency and ensuring the safety of this new energy source. Because sludges are composed of solids and gas mixture, the combustion of the mixture may become quite complex. Not only decomposition of conventional organic elements but also dust explosion may be important during the process of converting sludges into a new and safe form of energy. Sludge combustion mainly involves hydrogen, methane, hydro carbons, carbon, and organic particles. Dust explosion during the gasification stage may depend on the surrounding temperature and the composition of gases. The uncertainty in the explosive behavior of energetic source is noted in this work. We study the explosion characteristics of sludge combustion while the reusability of sewage sludges as a new form of energy is also investigated.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1388-1398
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• 2011

Air pollution in subway tunnel is primarily caused from the wear of metallic materials. As undesirable substance, PM(Particulate Matter) can especially harm the health of passengers and workers as well as clog the main parts of rolling stock such as inverters. To improve the air quality in subway tunnel, SMRT(Seoul Metropolitan Rapid Transit Corporation) has developed anti-pollution devices such as Magnetic Dust Collector, Vacuum Cleaner For Rail Road and Particulate Removing Sprinkler Vehicle. Introducing these mechanical devices, this paper is mainly devoted to explaining the characteristics of collected dust according to the result of particle-size analysis and componential analysis.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.3
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• pp.133-139
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• 2018

Precipitator is the most widespread device used to separate dust particles from the exhaust gas. In the shipyard, welding umbrellas, spark protection covers, and ventilators are not purchased and used for the work place to capture the flames and high temperature metal dust generated during the gardening process. In particular, a thorough analysis of design factors, such as capture rate, collection capacity calculation, filter speed, and materials selection, is required since spatial constraints are followed by structures, etc. In this study, conceived to address problems such as this cyclone and filtration filter system that combines all-in-one gausing collector prototype. Assessed through interpretation through the validity of the design and reliability.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.216-225
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• 2003

Fine particles with aerodynamic diameter less than 2.5 ${\mu}m$ (PM2.5) were collected from three sites in Beijing during April, August, and November 2000 and January 2001. After chemical components in samples are analyzed, a chemical mass balance (CMB) receptor model using PARs as tracers is applied to quantify the source contributions to PM2.5 in Beijing. The results show that the major sources are coal combustion, fugitive dust, vehicle exhaust, secondary sulfate and nitrate, and organic matter while biomass burning and construction dust contribute only a small fraction. In addition, source inventory in Beijing is used to determine the primary source contributions. The two methods result in comparable results. Source apportionment at three sampling sites presents similar contributions to PM2.5 although the sites are far away from each other. However, distinct seasonal pattern is presented for the source contributions from coal combustion, fugitive dust, biomass burning, secondary sulfate and nitrate.

• Journal of Integrative Natural Science
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• v.3 no.2
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• pp.84-88
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• 2010

Photonic crystals containing rugate structures from a single crystalline silicon wafer was obtained by using a sinoidal alternating current during an electrochemical etch procedure. Photonic crystals were isolated from the silicon substrate by applying an electropolishing current and were then made into particles by using an ultrasonic fracture in an ethanol solution to give a smart dust. Smart dusts exhibited their unique nanostructures and optical characteristics. They exhibited sharp photonic band gaps in the optical reflectivity spectrum. The size of smart dust obtained was in the range of 10-20 nm.

• Journal of Energy Engineering
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• v.5 no.2
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• pp.131-137
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• 1996

Typical size distribution of emission particulates is bi-modal in shape with particles in the fine mode (< 2.0 $\mu\textrm{m}$) and the coarse mode. An experimental study of pressure drop across the industrial gas cleaning filters has been conducted using particle mixture of fine alumina and coarse Arizona dusts with a rotating aerosol disperser to generate the bi-modal test aerosol. Pressure drop increased linearly with increasing mass loading. The pressure drop was found to be strongly dependent upon the mass ratio of fine to coarse particles. The smaller the mass ratio of fine to coarse particles and the higher face velocity are, the faster pressure drop rises. The fine particles and the greater inertia of the particle moving fast would cause a denser cake formation on the filter surface, resulting in a greater specific resistance to the gas flow.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.740-745
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• 2000

Effects of porous fences on the wind erosion of sand particles from a triangular pile were investigated experimentally. The porous fence and sand pile were installed in a simulated atmospheric boundary layer. The mean velocity and turbulent intensity profiles measured at the sand pile location were well fitted to the atmospheric boundary layer over the open terrain. Particle motion was visualized to see the motion of windblown sand particles qualitatively. In addition, the threshold velocity were measured using a light sensitive video camera with varying the fence porosity ${\varepsilon}$. As a result, various types of particle motion were observed according to the fence porosity. The porous wind fence having porosity ${\varepsilon}=30%$ was revealed to have the maximum threshold velocity, indicating good shelter effect for abating windblown dust particles.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.E1
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• pp.45-48
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• 2006

Mass size distributions of atmospheric particles in Cheonan were determined using a high volume air sampler equipped with a 5-stage cascade impactor. Bimodal distributions that are typical for urban atmospheric particles were obtained. A MMD of the fine particle mode was $0.47{\pm}0.05{\mu}m$ with a GSD of $2.72{\pm}0.21$, and those of the coarse particles were $5.15{\pm}0.18{\mu}m\;and\;2.09{\pm}0.09$, respectively. The annual average concentrations of TSP, PM10, PM2.5, and PM1 were 74.1, 67.5, 54.2, and $42.3{\mu}g/m^3$, respectively. Although the daily PM10 concentrations were under the current National Standard, the daily PM2.5 concentrations frequently exceeded the US Standard even in non asian dust periods. The fractions of PM 10, PM2.5, and PM1 in TSP were $0.905{\pm}0.013,\;0.723{\pm}0.022,\;and\;0.572{\pm}0.029$, respectively, and fine mode particles occupied $57{\sim}72%$ of the total particle mass. The results indicate that fine particles were at the concerning level, and should be the target pollutant for the regional air quality strategy in Cheonan.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.5
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• pp.685-695
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• 2004

Size-segregated measurements of aerosol composition are used to estimate the transport of natural and anthropogenic aerosols at Gosan site during May 2002. The results of measurement show that not only soil dust but also anthropogenic aerosols, including sulfur and enriched trace metals such as Pb, Zn, Cu, are transported to Gosan. This study combines the size- and time-resolved aerosol composition measurements with factor analysis in order to identify some source materials. As a result, coarse particles (2.5${\mu}m$~12${\mu}m$) are influenced by soil, sea-salt, coal, coal combustion, and nonferrous sources. But fine particles have different sources. The fine particles, which the diameter is from 0.56${\mu}m$ to 2.5${\mu}m$, are more affected by road dust, oil combustion, industry. municipal incineration, and ferrous metal sources. The very fine particles, from 0.09${\mu}m$ to 0.56${\mu}m$, mainly supplied by biomass burning, oil combustion, nonferrous and ferrous metal sources.