• 한국입자에어로졸학회지
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• 제19권3호
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• pp.89-100
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• 2023

In our previous study, a wire-plate type electrostatic precipitator (ESP) was developed to collect bioaerosols of 100 nm size. In the study, various flow rates (40 ~ 100 L/min) and applied voltages (3 ~ 10 kV) were tested for experiment. In this study, numerical analysis was performed for the ESP of the previous study with the same flow rates and applied voltages, but with varying the size of bioaerosols to 0.04 ~ 2.5 ㎛. Overall, the numerical analysis results well predicted the experimental data. Bioaerosols of 0.1 ~ 0.5 ㎛ showed the minimum collection efficiency for all conditions because of low charge number. The effect of the ionic wind generated by the corona discharge was calculated. However, the ionic wind did not affect much the collection efficiency. The aerosol collection in the ESP of this study was due to the electrostatic force generated by particle charge in the electric field. This numerical study on the ESP can be used for the design and optimization of higher flow rate (> 100 L/min) ESP.

• Safety and Health at Work
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• 제8권3호
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• pp.296-305
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• 2017

Background: Surfactant-containing water sprays are commonly used in coal mines to collect dust. This study investigates the dust collection performance of different surfactant types for a range of coal dust particle sizes and charges. Methods: Bituminous coal dust aerosol was generated in a wind tunnel. The charge of the aerosol was either left unaltered, charge-neutralized with a neutralizer, or positively- or negatively-charged using a diffusion charger after the particles were neutralized. An anionic, cationic, or nonionic surfactant spray or a plain water spray was used to remove the particles from the air flow. Some particles were captured while passing through spray section, whereas remaining particles were charge-separated using an electrostatic classifier. Particle size and concentration of the charge-separated particles were measured using an aerodynamic particle sizer. Measurements were made with the spray on and off to calculate overall collection efficiencies (integrated across all charge levels) and efficiencies of particles with specific charge levels. Results: The diameter of the tested coal dust aerosol was $0.89{\mu}m{\pm}1.45$ [geometric $mean{\pm}geometric$ standard deviations (SD)]. Respirable particle mass was collected with $75.5{\pm}5.9%$ ($mean{\pm}SD$) efficiency overall. Collection efficiency was correlated with particle size. Surfactant type significantly impacted collection efficiency: charged particle collection by nonionic surfactant sprays was greater than or equal to collection by other sprays, especially for weakly-charged aerosols. Particle charge strength was significantly correlated with collection efficiency. Conclusion: Surfactant type affects charged particle spray collection efficiency. Nonionic surfactant sprays performed well in coal dust capture in many of the tested conditions.

• 한국의류학회지
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• 제23권7호
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• pp.1030-1039
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• 1999

The effect of surfactant mixture 9on detergency and soil redeposition in a dry-cleaning system was investigated employing Aerosol OT as an anionic surfactant and Span 80 as a nonionic surfactant. The effect of charge system on soil deposition was also investigated in order to determine the optimum condition at which soil redeposition is minimum,. Soil deposition instead of soil redeposition on cotton, polyester and wool fabrics was measured employing petroleum solvent and perchloroethylene as organic solvents. The results were as follows. 1. Surface tension or interfacial tension was not changed by the addition of any surfactant or surfactant mixtures. In petroleum solvent however interfacial tension between solrent and water decreased when surfactants were added and increased when surfactants were mixed,. 2. The maximum amount of water solubilization increased as the mole fraction of Aerosol OT increased and more water was solubilized in petroleum solvent than in perchloroethylene. 3. The detergency of cotton was greater and the soil deposition rate was lower in Span 80 solution than in Aerosol OT solution. The soil deposition on cotton fabric decreased when water was solubilized in Aersol OT solution 4. The detergency and soil deposition rate of polyester fabric did not change by the surfactant type of the addition of surfactant mixture and soil deposition rate increased bywater solubilization. 5. Soil deposition on wool fabric was very high when Arosol OT was employed in perchloroethylene and the soil deposition did not change greatly by water solubilization.

• 한국대기환경학회지
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• 제29권1호
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• pp.38-55
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• 2013

This study has been performed to select several indicators of long-range transport process that can be applied to the Northeast Asia. We first classified high air pollution days into long-range transport (LRT) dominant cases and the local emission dominant (LED) cases based on the synoptic meteorological variables including vorticity and geostrophic wind speed/direction at a geopotential level of 850 hPa. LRT cases were further categorized into two types: LRT-I type with air mass pathways from northern China and/or Mongolia, and LRT-II type from central and southern China. In each categorized case, we examined the difference of both measured aerosol optical properties of AERONET at two sites in western Korea, and the simulated characteristics of LRT process by MM5-CMAQ model. We contrasted LRT case with LED case, and then generated the LRT indicators applicable to Northeast Asia. The results showed that fine and coarse modes of LRT-II were relatively smaller than LED and LRT-I cases, respectively. Aerosol size distribution showed significantly higher concentration of fine-mode particle (mainly smoke or urban aerosols) in LED case in comparison with that of LRT groups (LRT-I, II), suggesting the amplitudes fine modes of LRT relative to LED as a possible LRT indicator. From the results of MM5-CMAQ modeling, we concluded that the conversion ratios for sulfur ($F_s$) were the most effective indicators of LRT cases, and the ratio of VOC to NOx and NOx to CO were found to be the second most effective indicators of LED case.

• 대기
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• 제33권3호
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• pp.319-330
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• 2023

As the need for PM type observation increases, Surface Particulate Matter Network (SPARTAN), PM samplers analyzes aerosol samples for PM mass concentration and chemical composition, were recently installed at two sites: Yonsei University at Seoul and Ulsan Institute of Science and Technology (UNIST) at Ulsan. These SPARTAN filter samplers and nephelometers provide the PM_2.5 mass concentration and chemical speciation data with aerosol type information. We introduced the overall information and installation of SPARTAN at the field site in this study. After installation and observation, both Seoul and Ulsan sites showed a similar time series pattern with the daily PM_2.5 mass concentration of SPARTAN and the data of Airkorea. In particular, in the case of high concentrations of fine particles, daily average value of PM_2.5 was relatively well-matched. During the Yonsei University observation period, high concentrations were displayed in the order of sulfate, black carbon (BC), ammonium, and calcium ions on most measurement days. The case in which the concentration of nitrate ions showed significant value was confirmed as the period during which the fine dust alert was issued. From the data analysis, SPARTAN data can be analyzed in conjunction with the existing urban monitoring network, and it is expected to have a synergetic effect in the research field. Additionally, the possibility of being analyzed with optical data such as AERONET is presented. In addition, the method of installing and operating SPARTAN has been described in detail, which is expected to help set the stage for the observation system in the future.

• 한국세라믹학회지
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• 제40권8호
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• pp.715-719
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• 2003

The Aerosol Deposition (AD) process will be proposed as a new fabrication technology for the integrated RF modules. $\alpha$-A1$_2$O$_3$ thick films were successfully grown on glass and Al substrates at room temperature by the AD process. Relative dielectric permittivity and loss tangent of the $Al_2$O$_3$ thick films on Al showed 9.5 and 0.005, respectively. To form microstrip lines on aerosol-deposited A1903 thick films, copper electroplating and lithography processes were employed, and the square-type cross section with sharp edges could be obtained. Low-pass LC filters with 10 GHz cutoff frequency were simulated by an electromagnetic analysis, exhibiting the validity of the AD process as a fabrication technology f3r integrated RF modules.

• 한국입자에어로졸학회지
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• 제9권4호
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• pp.239-246
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• 2013

The purpose of this study is to determine the feasibility of dry-type desulfurization process for actual application to coal-fired power plant. We used actual exhaust gas from Facility Y, Plant #2 to fabricate a demo-scale testing device to attempt to improve the efficiency of desulfurization. A spout-bed circulating dry scrubber convergence system connecting turbo reactor with bag filter was devised, then analyzed for performance characteristics of $SO_2$ removal for Ca/S mole ratio, superficial gas velocity, and ammonia injection, and for secondary reaction characteristics of the non-reactive sorbent at the bag filter. As a result, the installation of spout-bed circulating dry scrubber convergence system showed better economy and efficiency for removing sulfur than the existing wet/semidry-type desulfurization process. In addition, the best efficiency for desulfurization occurred when connected to the bag filter, with differential pressure maintained at 150 $mmH_2O$.

• 한국입자에어로졸학회지
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• 제8권2호
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• pp.55-68
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• 2012

Particulate matters (PM) which are collected into a diesel particulate filter (DPF) system have to be periodically removed by thermal oxidation. In this report, we fabricated an electrohydrodynamic-assisted pressure-swirl nozzle to spray diesel droplets finer. Atomization performance of the nozzle was evaluated using both experimental and numerical methods. Two types of nozzle designs, the charge induction type and the charge injection type, were tested. While the former generated diesel droplets of $400\;{\mu}m$ at an applied electric potential over 10 kV, the latter presented the droplets smaller than $23\;{\mu}m$ at an applied electric potential of 8 kV. The numerical simulation results showed that the reduced size of droplets caused higher evaporation of droplets and therefore the increased temperature, which would eventually increase the regeneration performance of the DPF system.

• 한국입자에어로졸학회지
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• 제8권1호
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• pp.37-43
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• 2012

In this study, we designed a 'spark in liquid' system. The spark discharge between two electrodes were used to generate particles by using sufficient temperature to evaporate a part of electrodes. The power supply system provides a continuous spark discharge by discharging of the capacitor to ionize the electrodes in liquid. The DC spark discharge system operates with 1-10 kV voltage. Processed copper and graphite rods were used to both electrodes with 1-3 mm diameter. There are several variables which can control the particle size and concentration such as gap distance between electrodes, applied voltage, operating liquid temperature, electrode type and liquid type. So we controlled these variables to confirm the change of particle size distribution and concentration of particles contained in liquid as wt%. 'spark in liquid' system is expected to apply nanoink by control of concentration with analysis of characteristics.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.844-849
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• 2008

In recent semiconductor manufacturing clean rooms, in order to improve clean room air quality, air washers are used to remove airborne gaseous contaminants such as $NH_3$, SOx and organic gases from outdoor air introduced into clean room. Meanwhile, there is a large quantity of exhaust air from clean room. From the energy saving point of view, heat recovery is useful for the reduction of air conditioning energy consumption for clean room. Therefore it is desirable to recover heat from the exhaust air and use it to reheat the outdoor air. However, so far there have not been sufficient studies of analyzing the comparison of the amounts of energy consumption and saving. In the present study, an experiment was conducted to investigate the energy consumption and heat recovery of a fin-coil type air washer system for semiconductor manufacturing clean rooms.