• Title/Summary/Keyword: dust particle

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AKARI-SDSS-GALEX SURVEYS: SPECTRAL ENERGY DISTRIBUTIONS OF NEARBY GALAXIES

  • Buat, V.;Yuan, F.T.;Takeuchi, T.T.;Giovannoli, E.;Heinis, S.
    • Publications of The Korean Astronomical Society
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    • v.27 no.4
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    • pp.317-320
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    • 2012
  • A sample of nearby galaxies was built from the AKARI/FIS all sky survey cross-correlated with the SDSS and GALEX surveys. The spectral energy distributions from 0.15 to 160 microns of these galaxies are analysed to study dust attenuation and star formation properties. The calibrations of the amount of dust attenuation as a function of the IR-to-UV flux ratio and the FUV-NUV colour are re-investigated: the former one is confirmed to be robust and accurate whereas the use of the FUV-NUV colour to measure dust attenuation is found highly uncertain. The current star formation rate given by the SED fitting process is compared to that directly obtained from the UV and total IR luminosities. It leads to an accurate estimate of dust heating by old stars. We emphasize the importance of such a sample as a reference for IR selected star forming galaxies in the nearby universe.

Relationship between the Outer Vortex and the Collection Efficiency with respect to Temperatures in the Cyclone Dust Collector (사이클론 집진장치의 내부온도에 따른 외부 소용돌이와 집진효율의 관계)

  • Hyun, Daegeun;Chang, Hyuksang
    • Particle and aerosol research
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    • v.11 no.2
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    • pp.47-55
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    • 2015
  • This study compares the results of collection efficiency of difference gas temperature in cyclone dust collector. The previous researcher's experiment results were used to confirm the reliability of CFD(Computational Fluid Dynamics) model. Based on this verified CFD model, we extended the analysis on the cyclone dust collectors. In CFD study, we used RNG k-epsilon model for analysis of turbulence flow, fluid is air, the velocity at inlet is 10 m/s, the temperature of air is $20^{\circ}C$, $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$, $600^{\circ}C$ and $1000^{\circ}C$. As the temperature decreases, the average velocity of outer vortex and collection efficiency is increased, showed the highest collection efficiency at $20^{\circ}C$. It can be inferred smooth flow in cyclone dust collector is difficult because air viscosity increases as temperature increases. The power required at $1000^{\circ}C$ is almost 18 times greater than that of $20^{\circ}C$ to get the similar collection efficiency.

Evaluation of Collection Efficiency of Electrostatic Precipitator for Removing Limestone Slurry Particles (석회석 슬러리 입자 제거를 위한 전기집진기 포집효율 평가)

  • Lee, Gi-Hyuk;Kim, Moon-Won;Yu, Tae-U;Yook, Se-Jin
    • Particle and aerosol research
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    • v.15 no.2
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    • pp.57-65
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    • 2019
  • Recently, there has been much research on the effect of fine dust on human body with increasing interest in the fine dust. Thermal power plant, which is considered as one of the main sources of fine dust, is reported to be responsible for 14% of the total amount of domestic fine dust in the Republic of Korea. Therefore, dust collecting devices in the thermal power plant need to be improved. In this study, the electrostatic precipitator (ESP) was considered to substitute for a mist eliminator used in flue gas desulfurization facility. By considering real situation in the flue gas desulfurization facility, the collection efficiency of the ESP was evaluated by using the sprayed limestone slurry particles. The collection efficiency of the ESP was higher than that of the mist eliminator, showing the possibility of replacing the mist eliminator with the ESP in flue gas desulfurization facility.

Performance Comparison of a Fabric Filter System with Centrifugal Force and a Conventional Fabric Filter System (원심력이 적용된 여과포집진장치와 기존 집진장치의 성능비교)

  • Kim Sang-Do;Park Young-Ok;Kang Yong
    • Journal of Korean Society for Atmospheric Environment
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    • v.20 no.6
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    • pp.739-748
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    • 2004
  • A hybrid dust-collector combining a fabric filter with centrifugal force was developed to enhance the performance of the conventional fabric filter systems and its performances were evaluated to compare to that of the existing dust collector. The pressure drop rapidly increased with increasing the elapsed time and the face velocity in two filtration systems. But the increasing ratio of a hybrid dust-collector compare to the existing dust collector was lower. This results were confirmed from the performance such as cleaning interval, residual pressure drop and dust loading rate. The overall collection efficiency of the hybrid dust-collector was more than 99.6% and this showed a improvement of 0.6~2% than that of the existing dust collector. Especially, the fractional collection efficiency at the particle size of around 1${\mu}{\textrm}{m}$ is about 4% higher than that of the existing dust collector.

Comparisons of Dust Collection Efficiency on the Tangental Entry and Axial-vane Type Cyclone (접선유입식과 축상유입식 사이클론의 집진효율 비교)

  • Yi, Chung-Seob;Lee, Chi-Woo
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.6
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    • pp.115-121
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    • 2011
  • This study is about comparison of tangental entry type cyclone dust collector with axial vane type cyclone dust collector. Cut diameter and dust collection efficiency of both collector was compared by theory and experiment. Cut diameter was calculated by an quasi-empirical formula by Lapple and Shepherd. Measurement of cut diameter was conducted by particle counter through dust generator. As the result, cut diameter obtained by experiment was a little larger than that by theory. But the error is within $0.5{\mu}m$ in both type of collector, so it could be confirmed that theoretical value and experimental value were almost identical. And, as flow rate increased, dust collection efficiency was increased. Also axial vane type showed higher dust collection efficiency than tangental entry type. Therefore, it can be said that axial vane type cyclone dust collector has higher performance than the other.

Chemical Composition Characteristics of Size-fractionated Particles during Heavy Asian Dust Event in Spring, 2010 (2010년 봄철 고농도 황사의 입경별 화학조성 특성)

  • Lee, Dong-Eun;Kim, Won-Hyung;Ko, Hee-Jung;Oh, Yong-Soo;Kang, Chang-Hee
    • Journal of Korean Society for Atmospheric Environment
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    • v.29 no.3
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    • pp.325-337
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    • 2013
  • The size-fractionated aerosol samples have been collected at Gosan Site of Jeju Island during the spring season of 2010, in order to examine the chemical composition characteristics of the Asian Dust and Non-Asian Dust particles. The concentrations of ${HCO_3}^-$, Al, and nss-$Ca^{2+}$ in $PM_{10}$ had tremendously increased during the heavy Asian Dust (March 20, 2010). The concentration ratios of Asian Dust to Non-Asian Dust for the soil species (nss-$Ca^{2+}$, ${HCO_3}^-$, Al, Fe, Ti, Mn) were 12.2~30.7, meanwhile those for the anthropogenic species (nss-${SO_4}^{2-}$, ${NH_4}^+$, ${NO_3}^-$, $K^+$, Zn, Pb, and Cu) were 2.9~7.8. During the heavy Asian Dust event, the concentration increase of ${NO_3}^-$ in $PM_{2.5}$ were much more apparent than those of nss-${SO_4}^{2-}$ and ${NH_4}^+$, and the soil species (nss-$Ca^{2+}$ and ${HCO_3}^-$) showed much higher concentration increase. The neutralization factor of $NH_3$ was higher than that of $CaCO_3$. However, the neutralization factor of $CaCO_3$ in $PM_{10}$ was exceptionally high during the heavy Asian Dust, showing the evidence of heavy migration of soil particles. From the study for size fractionated particles, it was found that nss-${SO_4}^{2-}$ and ${NH_4}^+$ were mostly distributed in fine particle mode, on the other hand, ${NO_3}^-$ existed evenly in both fine and coarse particle modes, and the soil species (nss-$Ca^{2+}$, Al, Fe, etc.) were mainly in the latter mode. During the heavy Asian Dust, in particular, the concentrations of ${NH_4}^+$, nss-${SO_4}^{2-}$, $K^+$, Zn, and Pb had increased in coarse particle mode as well.

Flame Propagation Characteristics Through Suspended Combustible Particles in a Full-Scaled Duct (이송 배관 내 분진폭발의 화염전파특성)

  • Han, OuSup
    • Korean Chemical Engineering Research
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    • v.47 no.5
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    • pp.572-579
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    • 2009
  • This study is to investigate experimentally the flame structure and propagation mechanism in dust explosions and to provide the fundamental knowledge. Upward propagating laminar dust flames in a vertical duct of 1.8 m height and 0.15 m square cross-section are observed and flame front is visualized using by a high-speed video camera. Also, the thicknesses of preheated and reaction zone have been determined by a schlieren, electrostatic probe and thermocouple. The thickness of preheated zone in lycopodium dust flame is observed to be 4~13 mm, about several orders of magnitude higher than that of premixed gaseous flames. From the experimental results by a PIV(Particle Image Velocimetry) system, a certain residence time of the unburned particle in preheated zone is needed to generate combustible gas from the particle. The residence time will depend on preheated zone thickness, particle velocity and flame propagation velocity.

Explosion Hazards of Aluminum Powders with the Variation of Mean Diameter (알루미늄 분진의 평균입경 변화에 따른 폭발위험성)

  • Han, Ou-Sup;Han, In-Soo
    • Journal of the Korean Institute of Gas
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    • v.18 no.4
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    • pp.21-26
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    • 2014
  • In this study, the explosion characteristic of aluminium powders have been investigated as a function of particle size using by a 20 L dust explosion apparatus (K$\ddot{u}$hner). The tested aluminium particle sizes were the volume mean diameter of 16, 33 and $88{\mu}m$. The lower explosion limit increases gradually with the increasing of dust particle diameter, respectively 40, 60, $125g/m^3$ in mean diameter of 16, 33 and $88{\mu}m$. Also the increase in particle size for each aluminum dusts was found to cause an decrease in explosion pressure and Kst of dust explosion index, and a increase in the lower explosion concentration. Research results may have important implications for aluminum powders utilization and safety operation.

Effect of Mean Diameter on the Explosion Characteristic of Magnesium Dusts (마그네슘의 폭발특성에 미치는 평균입경의 영향)

  • Han, Ou-Sup;Lee, Su-Hee
    • Journal of the Korean Institute of Gas
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    • v.17 no.4
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    • pp.33-38
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    • 2013
  • A study was carried out on the effect of particle size (mean diameter) on magnesium dust explosion. Experimental investigations were conducted in a 20-L explosion sphere, using 10 kJ chemical ignitors. Explosion tests were performed with three different dusts having mean diameter (38, 142, $567{\mu}m$) and the dust concentrations were up to $2250g/m^3$. The lower explosion limits(LEL) of magnesium dusts were about $30g/m^3$ at $38{\mu}m$ and $40g/m^3$ at $142{\mu}m$. LEL tended to increase with particle size and this means that the explosion probability of magnesium dust decreased with increase of particle size. The maximum explosion presssure ($P_m$) and $K_{st}$ (Explosion index) decreased with the increase of particle size. For magnesium powder of $567{\mu}m$, however, the explosive properties were not observed in the 5 kJ ignition energy.

A Study on the Educational Effectiveness of Fine Dust Particle Preventive Board Game Developed for Children (어린이를 대상으로 하는 미세먼지 예방 보드게임 개발을 통한 교육적 효과 연구)

  • Heo, Seol-Hwa;Lee, Dong-Lyeor;Kyung, Byung-Pyo
    • Journal of Korea Game Society
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    • v.16 no.6
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    • pp.101-110
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    • 2016
  • Currently, fires caused by fine dust particles are attracting people's attention increasingly. Fine dust particles are $2.5{\mu}m$ (micrometer) in diameter which cannot be seen by the naked eyes could penetrate deeply into the lungs and cause health problems. Although people are aware of the precautions against fine dust particles, they do not take actions because they are less aware of the hazards that fine dust particles can do. This study aims to investigate the effects of artificial and natural causes of fine dust particles. In order to improve awareness of fine dust particle prevention, the <우마이() Escape> board game was developed and tests were carried out to 20 children to find out the educational effects of the board game.