• 대기
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• 제18권1호
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• pp.25-32
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• 2008

Log normalized volume size distribution (dV/dlog$D_p$) with 52 size ranges from 0.5 to $20.0{\mu}m$ was measured for the cases of high $PM_{10}$ mass concentration (> $200{\mu}gm^{-3}$) using the Aerodynamic Particle Sizer (APS) at the Korea Global Atmosphere Watch Center (KGAWC) from 6 April, 2006 to 5 April, 2007. Black Carbon (BC), gaseous pollutants of $NO_X$ and $SO_2$ and ${\AA}ngstr\ddot{o}m$ exponent were also measured to examine the properties of the volume size distribution. From distinct difference of the high volume concentration (> $100{\mu}m^3cm^{-3}$), the volume size distribution for each event day was clasified into four types: (1) Type 1 had the high volume concentration for supermicron particles from 2.3 to $6.0{\mu}m$ and maximum average volume concentration was $160.7{\mu}m^3cm^{-3}$ at $3.5{\mu}m$. (2) Type 2 represented the high volume concentration in the both size range of submicron ($0.7-1.0{\mu}m$) and supermicron particles ($2.1-4.1{\mu}m^3cm^{-3}$ and $136.2{\mu}m^3cm^{-3}$ were found at 0.8 and $3.3{\mu}m$ respectively. (3) Type 3 showed the high volume concentration in the size range of $0.5-3.5{\mu}m$ and highest volume concentration of $201.1{\mu}m^3cm^{-3}$ at the particle size bin of $0.8{\mu}m$. (4) Type 4 was characterized by the high volume concentration for the fine particles less than $1.2{\mu}m$ and very high concentration of $446.8{\mu}m^3cm^{-3}$. ${\AA}ngstr\ddot{o}m$ exponent, concentration of gaseous ($NO_X$ and $SO_2$), and particle (BC) pollutants suggested that Type 1 was a typical volume size distribution for the Asian dust and Type 3 provided transportation of air pollutants. The distribution in Type 2 found to have both characteristics of the Asian dust and air pollutants, and Type 4 was took place during the foggy atmosphere containing high density of local pollutants. Based on the properties of volume size distribution, we can identify the three major events contributing the increase of $PM_{10}$ mass concentration, and hope to provide a guideline for discriminating the Asian dust from high $PM_{10}$ events. More case studies and longeto advance this determination method.

• 한국산업보건학회지
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• 제18권3호
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• pp.177-184
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• 2008

The purpose of this study was to compare the performance characteristics of Andersen and total suspended particulate (TSP) samplers in terms of particle size distribution (PSD) and mass sampling efficiency. In the present study, two Andersen and four TSP samplers were selected and tested to quantitatively estimate human exposure to fly ash representing industrial particulate matter (PM) in a carefully controlled chamber. The PSD characteristics, a mass median aerodynamic diameter and a geometric standard deviation, were found from the sampled PM of airborne samplers in the chamber. An Andersen sampler was compared with a TSP sampler quantified by a coulter counter multisizer, as a reference sampler, to describe the correlation of mass sampling efficiencies between two types of samplers. Overall results indicate that Andersen samplers overestimated small PM due to particle bounce phenomena between impaction stages. There was reasonably good correlation ($R^2$ = 0.89 and 0.91) between the mass sampling efficiencies of Andersen and TSP samplers during the two tests. However, the lower values of slope (0.71 and 0.72) in two tests showed that the Andersen sampler underestimated PM (> AD $10.1\;{\mu}m$) with sufficient inertia due to a relatively lower Andersen inlet velocity at 0.8 m/s comparing with the operating air velocity at 2.1 m/s in the sampling zone of a chamber.

• 한국안전학회지
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• 제39권1호
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• pp.96-103
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• 2024

The demand for mass calculation of offsite consequence analysis to conduct exhaustive single-unit or multi-unit Level 3 PSA is increasing. In order to perform efficient offsite consequence analyses, the Korea Atomic Energy Research Institute is conducting model optimization studies to minimize the analysis time while maintaining the accuracy of the results. A previous study developed a model optimization method using efficient plume segmentation and verified its effectiveness. In this study, we investigated the possibility of optimizing the model through particle size distribution setting by checking the reduction in analysis time and deviation of the results. Our findings indicate that particle size distribution setting affects the results, but its effect on analysis time is insignificant. Therefore, it is advantageous to set the particle size distribution as fine as possible. Furthermore, we evaluated the effect of multithreading and confirmed its efficiency. Future optimization studies should be conducted on various input factors of offsite consequence analysis, such as spatial grid settings.

• 한국분무공학회지
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• 제1권1호
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• pp.85-91
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• 1996

This experiment was undertaken to investigate spray characteristics of the conventional inject ion system and the ultrasonic energy added inject ion system. Sauter mean diameter was mesured under the variation of inject ion pressure and the spray distance. To measure the droplet size we used the Malvern system 2600C. The spray angle and mass distribution was analyzed to the CCD camera and the patternater. After experiment, it was found that the ultrasonic energy added injection system had smaller sauter men diameter of droplet, wider mass distribution and wider spray angle than the conventional inject ion system had.

• 한국자동차공학회논문집
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• 제5권2호
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• pp.80-86
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• 1997

This experiment was undertaken to investigate spray characteristics of the conventional injection system and the ultrasonic energy added injection system. Sauter mean diameter was measured under the variation of injection pressure and the spray distance. To measure the droplet size, we used the Malvern system 2600C. The spray angle and mass distribution were analyzed to the CCD camera and the patternater. After experiment, it was found that the ultrasonic energy added injection system had smaller Sauter mean diameter of droplet, wider mass distribution and wider spray angle than the conventional injection system had.

• Journal of Korean Society for Atmospheric Environment
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• 제22권E1호
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• pp.35-43
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• 2006

Ambient particle size distributions of PCBs and their dry deposition fluxes were measured at a site in Seoul to quantify dry deposition fluxes of PCBs and size characteristics of PCBs in the air, and to estimate ambient concentrations of gaseous PCBs and dry deposition fluxes. The dry deposition plate was used to measure dry deposition fluxes of particulate mass and PCBs and a cascade impactor and rotary impactor were used to measure ambient particle size distributions for small ($D_p<9{\mu}m$) and large ($D_p>9{\mu}m$) particles, respectively. Six sample sets were collected from April to July 1999. The fluxes of particulate total PCBs (the sum of 43 congeners) ranged from 160 to $607ng\;m^{-2}day^{-1}$. The size distribution of total PCBs was bimodal with two peaks in small particle size ($D_p{\sim}0.6\;and\;6{\mu}m$, respectively) and, thus, mass concentration being dominant in small particles. The mean particulate PCBs concentration was $6.9{\mu}g$ PCBs/g. The concentrations of PCB homologues in the gas phase were estimated based on the particle/gas partition coefficient ($K_p$) with the measured values of particulate PCBs in this study and they were comparable to those observed in other previous studies. Dry deposition fluxes were estimated by calculating dry deposition velocities.

• 한국입자에어로졸학회지
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• 제18권3호
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• pp.69-77
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• 2022

In order to understand the characteristics of fine particles emitted from coal-fired power plant stacks, it is important to analyze the size distribution and components of particles. In this study, particle size distributions were measured using the ejector-porous tube dilution device and an ELPI system at a stack in a coal-fired power plant. Main elemental components of particles in each size interval were also identified through TEM-EDS analysis for the particles collected in each ELPI stage. Particle size distributions based on number and mass were analyzed with component distributions from 0.006 to 10 ㎛. The highest number concentration was about 0.01 ㎛. The main component of the particles consisted of sulfur, which indicated that sulfate aerosols were generated by gas-to-particle conversion of SO2. In a mass size distribution, a mono-modal distribution with a mode diameter of about 2 ㎛ was shown. For the components of PM1.0 (particles less than 1 ㎛), the abundance order was F > Mg > S > Ca, and however, for the components of PM10 (particles less than 10 ㎛), it was in the order of Fe > S > Ca > Mg. The elemental components by particle size were confirmed.

• 한국분무공학회지
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• 제19권4호
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• pp.197-203
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• 2014

The liquid jet breakup has been studied in the areas such as aerosols, spray and combustion. The breakup depends on several physical parameters such as the jet velocity, the nozzle inner diameter, and the density ratio of the water to the jet. This paper deals with characteristics of the jet breakup according to the jet velocity and the nozzle diameter. In order to consider only hydrodynamic factors, all the experiments were conducted in non-boiling conditions. The jet behavior in the water pool was observed by high-speed camera and PIV technique. For the condition of the inner diameter of 6.95 mm and the jet velocity of 2.8 m/s, the debris size of 22 mm gave the largest mass fraction, 39%. For higher jet velocity of 3.1 m/s, the debris size of 14 mm gave the largest mass fraction, 36%. For the nozzle with inner diameter of 9.30 mm, the debris size distribution was different. For jet velocity of 2.8 m/s and 3.1 m/s, the debris size with the largest mass fraction was found to be 14 mm. It was identified that the debris size decreased as the diameter or the jet velocity increased.

• 한국대기환경학회지
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• 제22권5호
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• pp.653-660
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• 2006

Due to the stronger exhaust emission regulations and the introduction of advanced technology in Diesel engine, the specific Diesel particulate matters have decreased by about one order of magnitude since the 1980's. In recent years, particle number emissions rather than particulate mass emissions have become the subject of controversial discussions. Recent results from health studies imply that it is possible that particulate mass does not properly correlated with the variety of health effects attributed to Diesel exhaust. Concern is instead now focusing on nano-sized particles. This study has been performed for the better understanding about the Diesel nano-particle measurement and size distribution characteristics in the exhaust system of a turbo charged Diesel engine. A scanning mobility particle sizer(SMPS) system was applied to measure the particle number and size concentration of Diesel exhaust particles. As the experimental results, the number concentrations in the particle size (Dp<200 nm) were very sensitive to dilution conditions. Specially the changes in nano-particle number concentrations(Dp<50 nm) increased along the downstream of exhaust flow. Also we found the dilution conditions were influencing the condensation of SOF and $H_2O$ during dilution and cooling of hot exhaust.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2010년도 춘계학술대회 논문집
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• pp.402-403
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• 2010