• Journal of Environmental Impact Assessment
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• 제20권4호
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• pp.557-564
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• 2011

This study was conducted to investigate the sudden rise of fine particle concentration after the passage of typhoon USAGI and NARI in Busan. Nocturnal inversion layer was formed at atmospheric boundary layer and wind direction changed from southerly wind to northeasterly wind after USAGI passed through Busan. Fine particle concentration in Busan rapidly increased by subsidence of air pollutants released from sources and dust transported from in the vicinity of industrial regions. Wind direction changed from northeasterly wind to southeasterly wind, wind velocity increased and lower atmosphere became extremely unstable after NARI passed through Busan. $PM_{10}$ concentration of Busan increased sharply because of surface dust dispersed by strong wind. Fine particle concentration generally decreases by precipitation and wind after typhoon passes through. However, the concentration can also go up not only by subsidence and transportation in nocturnal inversion layer but also by surface dust which temporarily occurs by strong wind.

• Clean Technology
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• 제5권1호
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• pp.30-41
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• 1999

The experimental set-up with a 1m long ceramic candle filter of Schumacher(Germany) was built in this work. The dust velocity field around the filter was measured using PDPA. The effects of dust cake layer and dust inlet position on the dust velocity field were also analyzed. It was found that the filtration velocity decreases as the dust cake builds up on the filter. The filtration velocity largely decreases around the filters near the dust inlet since the dust cake develops fast there. The average dust velocity on the filter due to the pressure difference through the filter was measured to be 0.28m/s. More uniform dust velocity field around the filter was obtained when feeding dust in a lower position of the pressure vessel.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.442-444
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• 2012

Depolarization characteristics of aerosol and cloud measured by dual wavelengths polarization lidar are examined. Ratio of depolarization ratio (RDR) between 1064 and 532nm are analyzed and compared with spherical aerosols and cloud. RDR of dust aerosols is exponentially decreased according to the increase of depolarization ratio at 532nm. The RDR of spherical aerosol is in the range of 1.5~6, dust aerosol is 0.98~4, and cloud is 0.7~1.77. Vertical distribution of dust aerosol and Relative Humidity (RH) are compared. In general, the RH in the dust layer are in the range of 30~60%. However, higher RH is frequently observed in the dust aerosols layer. In the condition of higher RH over 75%, the RDR of the dust aerosol are also increased to the range of 2~4.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• 제53권4호
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• pp.404-412
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• 2017

A centrifugal cyclone dust collecting apparatus includes a hydro cyclone dust collecting apparatus for separating solid or liquid using liquid or suspension as a medium. In this study, the formation mechanism and improvement of air core and inner air layer were confirmed through Particle Image Velocimetry. These results showed that the modified experimental model was designed in the conventional method suitable for the separation of juvenile fish and eggs. The inlet speed of the multi-stage hydrocyclone dust collector, which can increase the inlet velocity and minimize floatage in the turbulence chamber, was increased from 0.15 to 0.30 m/s. As a result, the air core was stably formed, the inner air layer was increased with increasing speed. In addition, the dust collecting efficiency of egg and juvenile fish was 97.8% on average, It can infer that this system confirmed the ability to efficiently collect particles of $40{\mu}m$ or more.

• Journal of The Korean Society of Agricultural Engineers
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• 제64권1호
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• pp.99-110
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• 2022

In this study, the generation and emission characteristics of particulate matter and gaseous matter in a mechanically ventilated layer house were evaluated. Each concentration of PM₁₀, PM_2.5, inhalable dust, respirable dust, and NH₃ was measured and compared with occupational limit considering seasons and respiratory disorder. CAPPS (Clean Air Policy Support System) of the Ministry of Environment proposes the emission factors of PM₁₀, PM_2.5, and NH₃ for a layer houses however, emission factors are still calculated from foreign factors such as CONINAIR values. As a result, it is urgent to develop national emission factors for domestic layer house. Emission coefficients of the studied mechanically-ventilated layer house in a summer season were calculated as 0.052 kg/head/year for PM₁₀, about 12% lower than that of CAPSS, and 0.0068±0.0038 kg/head/year for PM_2.5, showing no significant difference. Emission factor of NH₃ was calculated as 0.159±0.031 kg/head/year, about 51% lower than that of CAPSS.

• The Bulletin of The Korean Astronomical Society
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• 제35권2호
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• pp.73.2-73.2
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• 2010

In order to understand internal dynamics of starless cores, molecular line emissions are usually observed. From profiles of the molecular lines, internal motions of starless cores have been deduced using a simple radiative transfer model such as the two-layer model (Myers et al.1996). This brings complexities arising from the chemical evolution. The motivation of this study is to follow the chemical evolution of a starless core that goes through gravitational contraction. For this purpose, we have performed hydrodynamical simulations with a marginally unstable Bonnor-Ebert sphere as an initial condition. We follow the chemical evolution of this core with changing conditions such as the chemical reaction rate at the dust surface and the strength of radiation field that penetrate into the core. At the core center, the molecules suffer from a higher degree of molecular depletion on the dust covered by ice rather than on the bare silicate dust. The stronger radiation field dissociates more molecules at the core envelope. From analysis on the line profile using the two-layer model, we found that the speed of inward motion deduced from the HCN F = 2-1 line adequately traces the true infall speed, when the dust is covered by ice and the core is exposed to the diffuse interstellar radiation field. Under different conditions, the two-layer model significantly underestimate the infall speed.

• The Bulletin of The Korean Astronomical Society
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• 제36권2호
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• pp.71.1-71.1
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• 2011

Significant discrepancies have been found between the dust masses of edge-on spiral galaxies derived from various tracers (optical/near-infrared, far-infrared/sub-millimeter observations, and the variation of dust attenuation with viewing angle). Here we report the first detection of a vertically extended far-ultraviolet (FUV) and near-UV (NUV) emission in an edge-on spiral galaxy NGC 891. The vertically extended emission is interpreted as the dust-scattered light due to a extraplanar dust layer in NGC 891 that contains about the same mass as the standard thin dust disk. This new dust component completely encloses the stellar disk and bulge, and solves the puzzle of dust mass.

• The Journal of Engineering Geology
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• 제17권2호
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• pp.279-287
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• 2007

An ore of stone obtained from quarry lose its about 60% such as the muck and the stone-dust during the process of making the architectural block, the crushed aggregate and so on. A part of the muck is only reutilized for the crushed aggregate as road pavement materials, while the most of the muck in the shape of powder is mixed with water and then it is deposited in a sludge tank. The muck in the shape of powder is called the stone-dust. If the stone-dust is discharged and sprayed, an ecosystem will have terrible damage because the seepage of surface water, the flow of ground water and the movement of air are not occurred smoothly by packing the void of soils. As the Waste Management Law (2003) in Korea, the stone-dust is sorted out the industrial waste and the most of that is dumped in ground. Therefore, the establishments of an efficient recycling plan are necessary through the improvement of engineering properties of the stone-dust. To investigate the possibility of recycle and improvement for the stone-dust, the stone-dust and natural soils are sampled from six quarries in Korea. The various soil tests are performed by use of the mixed soils with the stone-dust content ratio. As the result of various soil tests, the recycle possibility of the stone-dust is analyzed as subbase layer materials of the roads.

• Journal of Korean Society for Atmospheric Environment
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• 제28권1호
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• pp.86-93
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• 2012

We present a retrieval method to obtain dust backscatter coefficient from the mixed Asian dust and pollutant layer. In the present study, vertically resolved quartz (silicon dioxide, silica) concentration was calculated using Raman scattering signals from quartz at 546 nm. Dust concentration was obtained based on typical mass percentage of quartz in Asian dust. The highest value of dust concentration at 3.7 km in March 21, 2010 was 22.3 and 10.9 ${\mu}gm^{-3}$ according to the quartz percentage in Asian dust as 65 and 30% based on literature survey, respectively. OPAC (Optical Properties of Aerosol and Clouds) simulations were conducted to calculate dust backscatter coefficient. The retrieved dust concentration was used as an input parameter for the OPAC calculations. Utilization of quartz Raman channel in Lidar measurements is considered useful for distinguishing optical properties of dust and nondust aerosol in the mixing state of Asian dust.

• Journal of Korean Society for Atmospheric Environment
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• 제20권3호
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• pp.361-369
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• 2004

A metal fiber bed has seldom been applied to the practical filtration process despite its excellent mechanical and chemical stability. The filter-bed used in this work was highly porous with open structure, of which apparent porosity was 80 ∼ 90%. Although pressure loss across the filter-bed was very low, separation efficiency was found to be quite high. This paper focuses on the basic filtration mechanisms of a metal filter-bed and a thin ceramic filter from fly ash for reference. The experimental parameters were face velocity, dust loading and porosity of filter-bed. Pressure drop increased with increasing face velocity and dust feeding load for both filters. It also showed that dust particles deposited in the deep flow path, finally resulting in clogging the pore channels. It thereby indicates that the dominating mechanism of the metal filter-bed would be depth filtration. Meanwhile, the thin fly ash composite filters trapped the aerated dust mainly on the surface of the filter medium, so that the instantaneously formed dust layer might cause a steep increase of pressure drop across the filtration system.