• Title/Summary/Keyword: Particle mass

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Measurement and Analysis of Visibility lmpairment during June, 1994 in Seoul (1994년 6월 서울지역 시정장애의 측정 및 분석)

  • 백남준;이종훈;김용표;문길주
    • Journal of Korean Society for Atmospheric Environment
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    • v.12 no.4
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    • pp.407-419
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    • 1996
  • Characteristics of visual air quality in Seoul have been investigated between June 13 and 21, 1994. Optical properties (extinction coefficient and particle scattering coefficient), meteorological parameters (relative humidity, temperature, wind speed, wind direction, and cloud cover), particle characteristics (mass size distribution, components) were measured and analyzed. During measurement periods, northwest wind with less than 2m/sec of wind speed deteriorates visibility. Effects of relative humidity are though to be not a direct factor which influence to visibility through the size change due to hygroscopic species in aerosol. During the smoggy period both the aerosol mass concentration and fine particle fraction of the size distribution are increased compared to the clear period. Sulfate, organic carbon, and elemental carbon in aerosol are the major species in determining the occurrence and severity of a smog in Seoul.

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Combustion Characteristics of Immobilized Alcohols in Sands (모래에 함침시킨 알콜의 연소특성)

  • 우인성
    • Journal of the Korean Society of Safety
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    • v.11 no.3
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    • pp.137-142
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    • 1996
  • Combustion characteristics of immobilized methyl, ethyl and propyl alcohols on sands were studied. Experiments were performed by burning methyl, ethyl and propyl alcohols Immobilized on sands (particle size 0.1~5mm) and ceramic balls(particle size 5mm) to measure mass burning rate, height burning rate and combustion temperature. It was concluded that the longer time from ignition to extinguishment was resulted from the larger particle size of sands and the smaller size of sands exhibited the higher mass burning rate. Of alcohols tested the relative magnitude of facilitation of combustion was methyl>ethyl>propyl alcohol. Combustion temperature of alcohols, without regard to the types of alcohols, was not increased with smaller sands. However, with larger sands, combustion temperatare of alcohols was increased with the larger particle.

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A numerical model for combustion process of single coal particle in hot gas (고온 유동장 내 석탄 단입자 연소과정의 특성화를 위한 수치적 연구)

  • Niu, Xiaoyang;Lee, Hookyung;Choi, Sangmin
    • 한국연소학회:학술대회논문집
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    • 2015.12a
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    • pp.301-304
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    • 2015
  • With the experiment observation of single particle combustion, this model is built for the numerical analysis of the process. It's about the single coal particle combustion process under different conditions with reasonable assumptions. The model can express the mass, radius, density, temperature changing with different particle sizes, oxygen concentration and gas temperature. It also includes the flame sizes change in different condition and the diffusion of each species. The result shows the characters of the combustion.

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Estimation of Mass Size Distribution of Atmospheric Aerosols Using Real-Time Aerosol Measuring Instruments (실시간 에어로졸 측정장비를 이용한 대기 중 입자상 물질의 무게 농도 분포의 추정)

  • Ji, Jun-Ho;Bae, Gwi-Nam
    • Particle and aerosol research
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    • v.9 no.2
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    • pp.39-50
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    • 2013
  • Real-time aerosol measuring instruments have been widely used for the measurement of atmospheric aerosol, diesel particulate matter, or material synthesis. A scanning mobility particle sizer (SMPS) measures the number size distribution of particles using electrical mobility detection technique. An aerodynamic particle sizer (APS) is used to determine the number concentration and the mean aerodynamic diameter of test particles. An electrical low-pressure impactor (ELPI) is a multi-stage impaction device to separate airborne particles into aerodynamic size classes using particle charging and electrical detection techniques. In this study, the performance of these instruments were evaluated to assess their ability to obtain mass concentrations from particle number concentration measurements made as a function of particle size. The effect of determination of particle density on the measurement of mass concentration was investigated for the three instruments.

Chemical Composition of the Size-resolved Particles in Buk-Ak Tunnel

  • Ma, Chang-Jin;Hwang, Kyung-Chul;Kang, Gong-Unn;Tohno, Susumu
    • Journal of Korean Society for Atmospheric Environment
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    • v.20 no.E2
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    • pp.53-59
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    • 2004
  • The roadway tunnels in urban areas give rise to problems such as a localized air pollution. Here, we report the results of a case study of an urban roadway tunnel measurement. The size-resolved particle sampling was carried out with a two 2-stage filter pack samplers and an Andersen impactor sampler at the center of Buk-Ak tunnel in November 2001. Particle Induced X-ray Emission (PIXE) was applied to determine the elemental composition of size-resolved particles divided into soluble and insoluble fractions. The Thermal/Optical Reflectance (TOR$^{(R)}$) method was also employed in analyzing of elemental carbon (EC) and organic carbon (OC). Mass concentrations of fine (< 1.2 ${\mu}{\textrm}{m}$) and coarse (> 1.2 ${\mu}{\textrm}{m}$) particles are 165 and 48 $\mu\textrm{g}$ m$^{-3}$ , respectively. Total elemental mass concentration (the sum of insoluble coarse, soluble coarse, insoluble fine, and soluble fine) is found to be 24$\mu\textrm{g}$ m$^{-3}$ and comprises only 11 % of total particle mass concentration. The concentrations of EC, OC, and mass show the clear dependency on particle size with the maximum between 0.1 and 0.43 ${\mu}{\textrm}{m}$ aerodynamic diameters. Total carbon (sum of EC and OC) accounts for approximately 70% of mass concentration.n.

Characteristics of Aerosol Mass Concentrations and Size Distribution Measured at Anheung, Korea (서해안 안흥에서 관측된 에어로솔의 농도 변화 및 크기분포 특성)

  • Lee, Kwon-Ho;Lee, Kyu-Tae;Kim, Jung-Ho;Mun, Gwan-Ho;Ahn, Joon-Mo
    • Journal of Korean Society for Atmospheric Environment
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    • v.34 no.5
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    • pp.677-686
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    • 2018
  • An intensive measurement was conducted to study the mass and number concentrations of atmospheric aerosols in Anheung ($36.679^{\circ}N$, $126.186^{\circ}E$), the west coastal measurement site of Korea during December 2017~April 2018. To evaluate relationships between the aerosols and meteorological parameters, comparisons of Optical Particle Counter (OPC) measured data and Auto Weather System (AWS) data were performed. Measured PM mass concentrations are $PM_{10}=42.814{\pm}30.103{\mu}g/m^3$, $PM_{2.5}=29.674{\pm}25.063{\mu}g/m^3$, $PM_1=28.958{\pm}24.658{\mu}g/m^3$, respectively. The PM ratios showed that the $PM_{10}$ concentrations contained about 67.8% of $PM_{2.5}$, while most part of $PM_{2.5}$ was $PM_1$ (about 97.1%). Timely collocation with AWS data were performed, exploring relations with the PM concentrations. PM concentrations can be explained by wind direction and relative humidity conditions. The significant reductions of fine particles in mass and number concentrations may attribute to actions on particle growth and wet removal. In these results, we suppose that the aerosol concentrations and size distributions are affected by inflow direction and air mass sources from the origin.

Relationships between a Calculated Mass Concentration and a Measured Concentration of PM2.5 and Respirable Particle Matter Sampling Direct-Reading Instruments in Taconite Mines (타코나이트 광산 공정에서의 실시간 질량측정기기와 실시간 수농도의 환산에 의한 질량농도와의 연관성)

  • Chung, Eun-Kyo;Jang, Jae-Kil;Song, Se-Wook;Kim, Jeongho
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.24 no.1
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    • pp.65-73
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    • 2014
  • Objectives: The purposes of this study are to investigate workers' exposures to respirable particles generated in taconite mines and to compare two metric methods for mass concentrations using direct-reading instruments. Methods: Air monitorings were conducted at six mines where subjects have been exposed primarily to particulate matters in crushing, concentrating, and pelletizing processes. Air samples were collected during 4 hours of the entire work shift for similarly exposure groups(SEGs) of nine jobs(N=37). Following instruments were employed to evaluate the workplace: a nanoparticle aerosol monitor(particle size range; 10-1000 nm, unit: ${\mu}m^2/cc$, Model 9000, TSI Inc.); DustTrak air monitors($PM_{10}$, $PM_{2.5}$, unit: $mg/m^3$, Model 8520, TSI Inc.); a condensation particle counter(size range; 20-1000 nm, unit: #/cc, P-Trak 8525, TSI Inc.); and an optical particle counter(particle number by size range $0.3-25{\mu}m$, unit: #/cc, Aerotrak 9306, TSI Inc.). Results: The highest airborne concentration among SEGs was for furnace operator followed by pelletizing maintenance workers in number of particle and surface area, but not in mass concentrations. The geometric means of $PM_{2.5}$ by the DustTrak and the Ptrak/Aerotrak were $0.04{\mu}m$(GSD 2.52) and $0.07{\mu}m$(GSD 2.60), respectively. Also, the geometric means of RPM by the DustTrak and the Ptrak/Aerotrak were $0.16{\mu}m$(GSD 2.24) and $0.32{\mu}m$(GSD 3.24), respectively. The Pearson correlation coefficient for DustTrak $PM_{2.5}$ and Ptrak/Aerotrak $PM_{2.5}$ was 0.56, and that of DustTrak RPM and Ptrak/Aerotrak RPM was 0.65, indicating a moderate positive association between the two sampling methods. Surface area and number concentration were highly correlated($R^2$ = 0.80), while $PM_{2.5}$ and RPM were also statistically correlated each other($R^2$ = 0.79). Conclusions: The results suggest that it is possible to measure airborne particulates by mass concentrations or particle number concentrations using real-time instruments instead of using the DustTrak Aerosol monitor that monitor mass concentrations only.

A Numerical Study of Heat and Mass Transfer Model of LII for Nanoscale Soot Particles (나노크기의 매연입자에 대한 LII의 열-물질 전달 모델에 관한 수치적 연구)

  • Kim, Gyu-Bo;Shim, Jae-Young;Chang, Young-June;Jeon, Chung-Hwan
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.7 s.262
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    • pp.596-603
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    • 2007
  • As increasing interest for soot emission. etc in combustion systems, various studies are being carried out for the reduction and measurement techniques of soot. Especially, laser induced incandescence is the useful measurement technique which has distinguished spatial and temporal resolution for primary particle size, volume fraction and aggregated particle size etc. Time resolved laser induced incandescence is the technique for measuring primary particle size that is decided to solve the signal decay rate which is related to the cooling behavior of heated particle by pulsed laser. The cooling behavior of heated particle is able to represent the heat and mass transfer model which are involved constants of soot property for surround gas temperature on the our previous work. In this study, it is applied to the time-dependence thermodynamic properties for soot temperature instead of constants of soot property for surround gas temperature and compared two different model results.

Measurement of the Particle Current Changes Associated with the Flatness of Deflector Mesh Surface in Particle Beam Mass Spectrometer System

  • Kim, Dongbin;Kim, TaeWan;Jin, Yinhua;Mun, Jihun;Lim, In-Tae;Kim, Ju-Hwang;Kim, Taesung;Kang, Sang-Woo
    • Applied Science and Convergence Technology
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    • v.25 no.2
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    • pp.25-27
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    • 2016
  • The surface flatness of metal meshes in a deflector of particle beam mass spectrometer (PBMS) required ideally flat, and this can specify the particle trajectories which goes through the detector. In this research, charged particle current was measured using the different surface roughness deflectors. NaCl particles were generated monodispersed in its size by using differential mobility analyzer and the whole processes were followed the way calibrating PBMS. The results indicate that the mesh surface morphology in the deflector can affect to the particle size and the concentration errors, and sensitivity of PBMS.

ENHANCEMENT OF DRYOUT HEAT FLUX IN A DEBRIS BED BY FORCED COOLANT FLOW FROM BELOW

  • Bang, Kwang-Hyun;Kim, Jong-Myung
    • Nuclear Engineering and Technology
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    • v.42 no.3
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    • pp.297-304
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    • 2010
  • In the design of advanced light water reactors (ALWRs) and in the safety assessment of currently operating nuclear power plants, it is necessary to evaluate the possibility of experiencing a degraded core accident and to develop innovative safety technologies in order to assure long-term debris cooling. The objective of this experimental study is to investigate the enhancement factors of dryout heat flux in debris beds by coolant injection from below. The experimental facility consists mainly of an induction heater, a double-wall quartz-tube test section containing a steel-particle bed and coolant injection and recovery condensing loop. A fairly uniform heating of the particle bed was achieved in the radial direction and the axial variation was within 20%. This paper reports the experimental data for 3.2 mm and 4.8 mm particle beds with a 300 mm bed height. The dryout heat density data were obtained for both the top-flooding and the forced coolant injection from below with an injection mass flux of up to $1.5\;kg/m^2s$. The dryout heat density increased as the rate of coolant injection increased. At a coolant injection mass flux of $1.0\;kg/m^2s$, the dryout heat density was ${\sim}6.5\;MW/m^3$ for the 4.8 mm particle bed and ${\sim}5.6\;MW/m^3$ for the 3.2 mm particle bed. The enhancement factors of the dryout heat density were 1.6-1.8.