• Particle and aerosol research
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• v.16 no.1
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• pp.1-8
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• 2020

Nano-pulse plasma technology has great potential as the process simplicity, high efficiency and low energy consumption for SO₂ removal. The research on the gas-to-particle conversion is required to achieve higher efficiency of SO₂ gas removal. Thus, we studied the effect of the relative humidity, NH₃ concentration and applied voltage of the nano-pulse plasma system in the gas to particle conversion of SO₂. The particles from the conversions were increased from 10 to 100 nm in diameter as relative humidity, NH₃ concentration, applied voltage increases. With these results, nano-pulse plasma system can be used to more efficient removal of SO₂ gas by controlling above parameters.

• Particle and aerosol research
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• v.12 no.1
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• pp.11-20
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• 2016

A large amount of wear dust generated during train operation is a major dust source in urban railway tunnels. To check possibility of a louver dust collector for the removal of dust in the railway tunnel, five louver dust collector models were designed and their performance was tested in a wind tunnel. JIS Z 8901 Class 8 dust was used as a test dust. Pressure drop and particle collection efficiency were evaluated with the face velocity ranging from 1 m/s to 4 m/s. At this low velocity range, particle collection efficiency of the louver dust collector was found to be insensitive to air velocity and design parameters. Pressure drop was under 40 Pa, and $PM_{10}$ and $PM_{2.5}$ collection efficiencies were approximately 50% and 30%, respectively.

• Particle and aerosol research
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• v.5 no.1
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• pp.1-7
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• 2009

Fe- and V-doped titanium dioxide nanoparticles consisting of spherical primary nanoparticles were synthesized from a mixed liquid precursor by using the flame spray pyrolysis. The effects of dopant concentration on the powder properties such as morphology, crystal structure, and light adsorption were analyzed by TEM, XRD, and UV-Vis spectrophotometer, respectively. As the V/Ti molar ratio increased, pure anatase particles were synthesized. On the contrary, rutile phase particles were synthesized as the Fe/Ti ratio increased. Photocatalytic property of as-prepared $TiO_2:Fe,V$ nanoparticles was investigated by measuring the removal efficiency for volatile organic compounds (VOCs) under the irradiation of visible light. After 2 hrs under visible light, the removal efficiencies of benzene, p-xylene, ethylbenzene, and toluene were reached to 21.9%, 21.4%, 19.8% and 17.6% respectively.

• Particle and aerosol research
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• v.15 no.4
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• pp.149-157
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• 2019

Infiltration characteristics of airborne particulate matter had been investigated in real-life for about 90 days over 2 years in a Korean apartment building where a 3-person household had lived and the exclusive private area was 84.9 ㎡. Airtightness was measured by fan depressurization, and the ACH₅₀ was 2.41 times per hour. In and outdoor particle concentrations were measured by optical particle counters. Infiltration factors and filtration efficiencies of the house, which reflect the removal of outdoor particles penetrating building envelope and the deposition inside a building, were obtained from data screened based on an empirical evaluation process. Infiltration factor of fine particles showed a range from about 42% at 0.4 m/s of wind speed to 72% at 4.2 m/s of wind speed with closed windows and doors. Filtration efficiency was like a MERV 13 grade filter with an open window outside at a balcony at low outdoor wind speed under 1 m/s. The grade decreased to MERV 11 by opening another outside window at the other balcony. Filtration efficiencies decreased as much as 29% in average at a range of 0.3~2.5 ㎛.

• Particle and aerosol research
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• v.18 no.4
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• pp.129-136
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• 2022

The line width of circuits in semiconductor devices continues to decrease down to a few nanometers. Since nanoparticles attached to the patterned wafer surface may cause malfunction of the devices, it is crucial to remove the contaminant nanoparticles. Physical cleaning that utilizes momentum of liquid for detaching solid nanoparticles has recently been tested in place of the conventional chemical method. Dropwise impaction has been employed to increase the removal efficiency with expectation of more efficient momentum exchange. To date, most of relevant studies have been focused on drop spreading behavior on a horizontal surface in terms of maximum spreading diameters and average spreading velocity of drop. More important is the local liquid velocity at the position of nanoparticle, very near the surface, rather than the vertical average value. In addition, there are very scarce existing studies dealing with microdroplet impaction that may be desirable for minimizing pattern demage of the wafer. In this study, we investigated the local velocity distribution in spreading liquid film under various impaction conditions through the CFD simulation. Combining the numerical results with the particle removal model, we estimated an effective cleaning diameter (ECD), which is a measure of the particle removal capacity of a single drop, and presented the predicted ECD data as a function of droplet's velocity and diameter particularly when the droplets are microns in diameter.

• Atmosphere
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• v.21 no.3
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• pp.301-309
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• 2011

In this study, we compared light-absorption properties of aerosols observed in East and South Asia from black carbon (BC) mass concentration, aerosol scattering (${\sigma}_s$) and absorption (${\sigma}_a$) coefficients measurements at four sites: Korea Climate Observatory-Gosan (KCO-G), Korea Climate Observatory-Anmyeon (KCO-A), Maldives Climate Observatory-Hanimaadhoo (MCO-H) and Nepal Climate Observatory-Pyramid (NCO-P). No significant seasonal variations of BC mass concentration, ${\sigma}_s$ and ${\sigma}_a$, despite of wet removal of aerosols by precipitation in summer, were observed in East Asia, whereas dramatic changes of light-absorbing aerosol properties were observed in South Asia between dry and wet monsoon periods. Although BC mass concentration in East Asia is generally higher than that observed in South Asia, BC mass concentration at MCO-H during winter dry monsoon is similar to that of East Asia. The observed solar absorption efficiency (${\alpha}$) at 550 nm, where ${\alpha}={\sigma}_a/({\sigma}_s+{\sigma}_a)$, at KCO-G and KCO-A is higher than that in MCO-H due to large portions of BC emission from fossil fuel combustion. Interestingly, ${\alpha}$ at NCO-P is 0.14, which is two times great than that in MCO-H and is about 40% higher than that in East Asia, though BC mass concentration at NCO-P is the lowest among four sites. Consistently, the highest elemental carbon to sulphate ratio is found at NCO-P.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.5
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• pp.659-667
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• 2018

$NO_x$ and $SO_2$ are mainly generated in the combustion of fossil fuels, and they cause secondary aerosol formation and acid rain in the atmosphere. Many studies have been conducted on the wet scrubbing process which can simultaneously reduce $NO_x$ and $SO_2$ at relatively low temperature. In this study, we conducted an experimental study on wet scrubbing by using NaOH solution. Especially, this study focuses on $NO_x$ and $SO_2$ removal characteristics by varying $NO_2/NO_x$ ratio and $SO_2$ concentration.

• Particle and aerosol research
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• v.15 no.4
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• pp.139-148
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• 2019

This study was performed for the application of a high-speed centrifugal cyclone to shale gas mining process. This device uses the centrifugal force to control particles similar to typical cyclones, and the disk located inside the cyclone is forced to rotate using a motor. The pressure difference occurred during the rotating of disk. Hence, inflow rate was generated without a blower fan. In addition, flow rate increased with elevating rpm of motor. The installing the disk in multiple stages on the inner rotor increased the instantaneous disk outlet flow. Hence, the control efficiency of oil particle increased from 1.05% to 31.2%. By modifying the structure of the disk so that the air flow to the opposite direction of the cyclone, the control efficiency of oil particles increased to 81.5%. By increasing the capacity of the motor and the size of the disk, the flow rate was increased to 2.5 ㎥/min because the rpm of motor and pressure difference increased. As rpm of motor increased, the cut-off diameter (d_pc) became smaller. Unlike the Lapple's equation, d_pc was inversely proportional to the effective number of rotations (N_e). The control efficiency was maintained even if the concentration of oil particles increased, for this reason, the higher the oil concentration, the more particles were accumulated and controlled.

• Particle and aerosol research
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• v.14 no.3
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• pp.81-88
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• 2018

The market for improving the indoor air quality is continuously increasing, and air cleaners are the representative products. As interest in indoor air quality increases, so are the ultrafine particle which are harmful to the human body. Despite its many advantages, electrostatic precipitators are less used in indoor air due to ozone production. In this study, the carbon fiber sheet was applied to the discharge electrode and compared with the conventional tungsten wire discharge electrode. The particle collection efficiency and the amount of ozone generation were measured for 10-100 nm particles. Furthermore, it was applied to commercial air purifier with electrostatic precipitator to compare particle removal performance. The carbon fiber sheet type discharge electrode generates a small amount of ozone, and thus it can be applied to improve indoor air quality.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1134-1138
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• 2008

Electret filter media are used in general ventilation filters, disposable respirators, vehicle cabin filters, vacuum cleaners and room air cleaners. There are basic mechanisms of interception, inertial impaction, diffusion, gravitational settling, electrostatic attraction by which an aerosol particle can be deposited onto a fiber in a filter. The ability of fine particle removal strongly depends on the electrostatic forces between particles and polarized fibers. Thus, the stability of the fiber polarization is a major factor in the reliability of electret filters. In this study, electrical properties and filtration performance of electrospun filter media are quantitatively investigated. Electrical properties of electrospun filters have been studied on surface charge potential and surface charge density. Also the filtration performance of the electret filters are evaluated on collection efficiency. Electrospun filters show same collection efficiency with low pressure drop compare to commercialized HEPA filters. Surface charge potential and surface charge density of electrospun filters are increased with increasing applied voltage. Also collection efficiency of electrospun filters is increased with increasing surface charge potential and surface charge density.