• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.5
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• pp.1639-1648
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• 1996

Protection of gas turbine blade from its erosion and abrasion at high temperature and pressure is the first goal to cleanup the hot gas upstream for IGCC and PFBC. Ceramic filters represent an attractive technology for particle removal at high temperature and high pressure condition. They have demonstrated being a good system for improvement of thermal efficiency and reduction of effluent pollutants in advanced coal-based power systems such as IGCC and PFBC. Ceramic filter elements currently being developed were evaluated in the previous paper. In this paper, we measured the ash size and distribution on cleaning of ceramic candle filter. The results are as follows : in this experimental range, ceramic candle filter was shown to be fully adequate for the removal process of dust under high temperature and pressure. Also filtration efficiency of ceramic candle filter was higher than 98% compared with the regulation limit of particle size in gas turbine inlet.

• Journal of Environmental Science International
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• v.21 no.5
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• pp.623-631
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• 2012

The adsorption behavior of Eosin Y on activated carbon (AC) in batch system was investigated. The adsorption isotherm could be well fitted by the Langmuir adsorption equation. The kinetics of adsorption followed the pseudo-second-order model. The temperature variation was used to evaluate the values of free energy (${\Delta}G^{\circ}$), enthalpy (${\Delta}H^{\circ}$) and entropy (${\Delta}S^{\circ}$). The positive value of enthalpy change ${\Delta}H^{\circ}$ for the process confirms the endothermic nature of the process and more favourable at higher temperature, the positive entropy of adsorption ${\Delta}S^{\circ}$ reflects the affinity of the AC material toward Eosin Y and the negative free energy values ${\Delta}G^{\circ}$ indicate that the adsorption process is spontaneous. With the increase of the amount of AC, removal efficiency of Eosin Y was increased, but adsorption capacity was decreased. And adsorption capacity was increased with the decrease of particle size. With the increase of the amount of AC, removal efficiency of Eosin Y was increased, but adsorption capacity was decreased. And adsorption capacity was increased with the decrease of particle size.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.2
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• pp.117-124
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• 2005

Appropriate removal of pollutants from combined sewer overflows(CSOs) and stormwater runoff is of primary concern to watershed managers trying to meet water quality standards even under a wet weather condition. Harmful substances associated with particles besides TSS and BOD are subjected to removal prior to discharge into the natural waters. Effectiveness of five major hydrodynamic separation technologies, Vortechs, Downstream Defender including Storm King for CSOs control, CDS, Stormceptor, and IHS, were evaluated in this study. There is not sufficient information for accurate evaluation of the removal efficiency for the pollutants from the stormwater runoff and CSOs. Based upon limited engineering data, however, all technologies were found to be effective in separation of heavy particles and floating solids. Technologies utilizing screens seem to have advantage in the treatment capacity than the other technologies relied fully on hydrodynamic behavior. The IHS system seems to have a strong potential in application for control of CSOs because of unique hydrodynamic behavior as well as a flexibility in opening size of the screens. Size of the particulate matter in the CSOs and stormwater runoff is found to be the most important parameter in selection of the type of the hydrodynamic separators. There exists an upper limit in the solids removal efficiency of a hydrodynamic separator, which is strongly dependent upon the particle size distribution of the CSOs and stormwater runoff.

• Nuclear Engineering and Technology
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• v.16 no.1
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• pp.29-35
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• 1984

Filtration efficiency tests were conducted on a fiberglass mat filter with DOP aerosol having a diameter from 0.l${\mu}{\textrm}{m}$ to 0.45${\mu}{\textrm}{m}$ in the face velocity range of 1cm/sec to 10cm/sec. Filtration of submicron particles by a fibrous filter is characterized by a face velocity. The size of DOP aerosol which has a minimum removal efficiency decreases with increasing the velocity. A numerical solution of the diffusion equation is obtained for a fiberglass mat filter by using "Kuwabara's cell model" for the flow field and Von Mises Transformation for the actual flow around a fiberglass. The present theoretical results agree quite well with the experimentals for fiberglass mat. This result could be contributed to predict the removal efficiency on an air filter and to optimize the operating condition of an air purification system with a filter. a filter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.795-801
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• 2010

As the fabrication technology of LCDs (Liquid Crystal Displays) advances, the size of mother glass substrates is getting larger, and the fabrication process is becoming finer. Accordingly, the importance of cleaning processes grows in the fabrication process of LCDs. In this study, we have compared and evaluated the particle removal efficiency for three different methods of physical cleaning, which are brush, bubble jet, and aqua/air cleaning. Using the seventh generation glass substrate, the particle removal efficiency has been investigated by changing operation conditions such as a flow rate of deionized water, pressure, contact depth between a brush bristle and a glass substrate, and so forth. In the case of brush cleaning, the cleaning efficiency barely changes after a critical point when the contact depth is varied. While the cleaning efficiency of bubble jet cleaning is almost independent of pressure, that of aqua/air cleaning is affected by pressure up to a critical point, but is not changed after it. We note the brush cleaning is the most effective among the three cleaning methods under our experimental conditions.

• 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 ㎛.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.151-155
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• 2007

A compact discharge plasma system with a photocatalyst has been proposed and investigated experimentally for application to air conditioners. It was found that there was intense ultra violet radiation with high energy of 3.2 eV from the corona discharge due to the DC-biased pulse voltage applied on a wire. An electrophotochemical reaction took place apparently on the surfaces of the photocatalyst of $TiO_2$ irradiated ultra violet front the discharge plasma in the proposed plasma system. The proposed discharge plasma system with the photocatalyst of $TiO_2$ showed very high removal efficiency of VOCs by tile additional electrophotochemical reactions on the photocatalyst. The proposed discharge plasma system also showed very high removal efficiency of particles such as smokes, suspended bacteria, and pollen and mite allergens by the electrostatic precipitation part. This type of corona discharge plasma system with a photocatalyst can be used as an effective means of removing both indoor pollutant gases and particles including suspended allergens.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.5
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• pp.634-641
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• 2013

Condensing species behaviour downstream of a combustor was discussed with particle size distribution in this study. The effects of operating conditions in a biomass combustion facility, i.e. concentration of condensing species, temperature gradient, residence time and injection of adsorbents, on particle size distribution were investigated. Pyroligneous liquid which was completely vaporized at the temperature higher than $350^{\circ}C$ was used as a representative of condensing gaseous species. We found that particle size downstream of a combustor increased with increasing heating temperature (i.e. concentration of condensing species) and residence time. However, temperature gradient was not an important factor to control the particle size. The addition of $SiO_2$ precursor as an adsorbent could effectively prevent the particle formation by adsorbing condensing gaseous species on $SiO_2$ particles, and increased the particle size up to 300 nm, resulting in increasing particle removal efficiency in a conventional air pollution control device.

• 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.

• Environmental Engineering Research
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• v.17 no.3
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• pp.145-150
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• 2012

Pb-contaminated soil at a clay shooting range was analyzed by the sequential extraction method to identify metal binding properties in terms of detrital and non-detrital forms of the soil. Most of the metals in the soils existed as non-detrital forms, exchangeable and carbonate-bound forms, which could be easily released from the soil by a washing method. Therefore, the characteristics of Pb desorption for remediation of the Pb-contaminated soil were evaluated using hydrochloric acid (HCl) by a washing method. Batch experiments were performed to identify the factors influencing extraction efficiency. The effects of the solid to liquid (S/L) ratio (1:2, 1:3, and 1:4), soil particle size, and extraction time on the removal capacity of Pb by HCl were evaluated. Soil samples were collected from two different areas: a slope area (SA) and a land area (LA) at the field. As results, the optimal conditions at 2.8 to 0.075 mm of particle size were 1:3 of the S/L ratio and 10 min of extraction time for SA, and 1:4 of the S/L ratio and 5 min of extraction time for LA. The characteristics of Pb desorption were adequately described by two-reaction kinetic models.