• Particle and aerosol research
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• v.18 no.1
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• pp.9-21
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• 2022

In this study, a novel antiviral coating method for the air filtration system of subway station was investigated. Using dry aerosol coating process, we developed a high-performance antiviral air filter with spark discharger and carbon brush type ionizer. Silver nanoparticles were produced by a spark discharge generation system with ion injection system and were used as antiviral agents coated onto a medium grade air filter. The pressure drop, filtration efficiency, and antiviral ability of the filter against aerosolized MS2 virus particles as a surrogate of SARS-CoV-2 virus were tested with dust contamination. Dust contamination caused the increase of the filtration efficiency and pressure drop, while the antiviral agents (in this study, silver nanoparticles) coating did not have any significant effect on the filtration efficiency and pressure drop. Using these properties, we suggested a novel method to maximize the antiviral performance of the antiviral air filter that was contaminated by dust particles. Moreover theoretical analysis of antiviral ability with dust contamination and re-coated antiviral agents was carried out using a mathematical model to calculate the time-dependent antiviral effect of the filter under actual conditions of subway station. Our model can be used to apply on antiviral air filtration system of subway station for prevention of pandemic diffusion, and predict the life cycle of an antiviral filter.

• Journal of ILASS-Korea
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• v.12 no.2
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• pp.86-93
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• 2007

There is a growing interest to develop an eco-friendly air cleaner with high performance through a remanufacturing process. Two kinds of polyurethane filter media, a coarse (Filter-A) and a fine filter media (Filer-B), are used in this study to protect a vehicle engine from airborne particles. In order to improve the collection performance of the filters (Filter-A, Filter-B), an oil coating technology on the filter surface was introduced. As a result, inertial force is a dominant collection mechanism for a dry filter media, so that collection efficiency increases with increasing filtration velocity. However, intra-structure change of an oil-coated filter media influences on the collection mechanism, which shows a non-linear collection efficiency curve in terms of filtration velocity. The result shows that the developed filter media are eco-friendly and effective to protect a vehicle engine from airborne particles especially at low filtration velocity.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.763-770
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• 2007

There are many design parameters affecting filtration efficiency such as filteration rate, media packing depth, size distribution, and so on. The sphericity, the ratio of the surface area of an equal volume sphere to the real surface area of the particles, is one of major physical characters of media. The effect of sphericity on the performance of anthracite filter has been investigated. Media from eight water treatment plants have been collected. The sphericity of each media has been calculated by using well known headloss equations such as Kozeny equation, Dahmarajah equation etc.. Columns packed with anthracite media having different sphericity have been used to compare headloss development, floc accumulation in the bed, particles in bed water, filtrate turbidities after backwash and so on. The repeated experiments have indicated that the sphericity of anthracite media may not have remarkable influence on the filter performance as it has been suspected. It also has been prospected in the experiment that the media of higher sphericity would store more particles in the bed and give better filtrate quality, if provided that the effective size and the size distribution of media would be the same.

• Membrane and Water Treatment
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• v.8 no.1
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• pp.89-112
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• 2017

Dyeing wastewaters are the most problematic wastewater in textile industries and also, growing amounts of waste fibers in carpet industries have concerned environmental specialists. Among different treatment methods, membrane filtration processes as energy-efficient and compatible way, were utilized for several individual problems. In this research, novel hybrid membranes were prepared by waste fibers of mechanical carpets as useful resource of membrane matrix and industrial graphite powder as filler to eliminate Chrysophenine GX from dyeing wastewater. These membranes were expected to be utilized for first stage of hybrid membrane filtration process including (adsorption-ultrafiltration) and nanofiltration in Kashan Textile Company. For scaling of membrane filtration process, fouling mechanism of these membranes were recognized and explained by the use of genetic algorithm, as well. The graphite increased rejection and diminished permeate flux at low concentration but in high concentration, the performance was significantly worsened. Among all hybrid membranes, 18% wt. waste fibers-1% wt. graphite membrane had the best performance and minimum fouling. The maximum pore size of this optimum membrane was ranged from 16.10 to 18.72 nm.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.697-704
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• 2008

Stormwater runoff from urban road area as non-point source has a tendency of including lots of pollutants at initial rain period. Recently, there are several cases of having installed treatment facilities for reducing pollution discharge from the impervious cover in urban area to prevent watershed environment from getting worse. The filtration type among non-point source treatment systems has been known as one of the most efficient system for treatment of non-point source pollutants. Therefore, various kinds of filter media such as expanded polypropylene(EPP), granular activated carbon, zeolite, perlite, illite, sand, gravel has been developed. This study was conducted to verify performance and hydraulic characteristics of filter media as measures for non-point source. The experiment was carried out to evaluate applicability and variation of 4 kind of most popular filter media(EPP, GAC, Zeolite, Perlite) in headloss with elapsed time and influent flow rate and to obtain data base that could be used to establish management plan for road runoff treatment. In experiment by tap water, it showed that EPP and perlite those are floatable materials showed stable operating performance and lower headloss than the others.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.1043-1050
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• 2020

Radioactive aerosols are produced during the cutting of contaminated and activated metals. They must be collected and removed by a high-performing filtration system before releasing to the environment from the decommissioning workplace. The filtration system requires regular replacement to ensure the sufficient removal of radioactive aerosols because its filtration efficiency gradually decreases. This study evaluates the efficiency and lifetime of filters while cutting metals by using a plasma arc cutter. Particularly, this study considers the aerodynamic diameter distribution of number and mass concentrations for aerosols from 6 nm to 10 ㎛ when evaluating the performance of filters. After 20 time reuses for cutting operation performed in a cutting chamber, the removal efficiency is reduced from over 99 to below 93% at 2 ㎛. The results are used to analyze the lifetime of filters, the frequencies of their replacements, and impact on internal radiation dose.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.172.2-172.2
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• 2010

This study was carried out in order to reduce the installation expense of heating system for greenhouse comparing to geothermal heat pump and develope the coefficient of performance (COP) for a heat pump. For getting plenty of heat flux from geothermal energy. Surface water in river channel was used for getting a lots of geothermal heat by penetrating water through underground soil layer of the river bank that make heat transmission to passing water. The range of water temperature after the process of Ground filtration is 13~18 degrees celsius which is very similar to low heat source of geothermal heat pump system and the plenty amount of heat source from that make the number of geothermal heat exchanging hole and the expense for geothermal heat exchanger construction reduced. Drainage well is also used for returning filtration water to the aquifer that keep the water good recirculation from losing geothermal heat and water resource. For the COP improvement of Heat pump, thermal storage tank with separating insulation plate according to the temperature difference make the COP of Heat pump that is similar to thermal storage tank with diffuser. Developed thermal storage tank make construction expense cheaper than customarily used one's. and that sand filter and oxidation sand (FELOX) are going to be used for improving ground filtration water quality that make heat exchanger efficiency better. All above developed component skill are going to be set on the Ground filtration water source heat pump system and applied for medium, large scale for protected greenhouse in riverside area and on-site experiment is going to do for optimizing the heating system function and overcome the problem happening in the process of on-site application afterward.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.5
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• pp.160-170
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• 2003

A pilot study was performed to examine the feasibility of intermittent slow sand filtration for agricultural reuse of reclaimed water. The effluent of biofilter for 16-unit apartment was used as influent to the slow sand filtration system at 0.6 $m^3$/day loading rate using 15 seconds spray in every 10 minutes on the about 1 $m^2$ surface area and 0.5 m depth. The influent concentrations of total coliform (TC), fecal coliform (FC) and E. coli were in the range of 10.000 MPN/100 mL. and they were reduced to less than 1,000 MPN/100 mL after filtration with average of 320, 270, and 154 MPN/100 mL, respectively, showing over 95 % removal. Turbidity and SS were improved effectively and their average concentration was reduced to 0.8 NTU and 1.7 mg/L, respectively, and removal rate was about 50 %. Average BOD and COD concentrations were also reduced substantially to 2.6 and 25.8 mg/L with about 55 and 21 % removal rate, respectively. Nutrients removal was relatively low and removal rate for T-N and T-P was low however, remaining nutrients might be beneficial and less concerned in case of agricultural reuse. The concentration of biofilter effluent used in this experiment was in the range of secondary treatment effluent but slightly stronger than the one from existing wastewater treatment plants (WWTPs). Therefore, intermittent slow sand filtration might be also applicable to the effluent from WWTPs as long as its agricultural reuse is available. Considering stable performance and effective removal of bacterial indicators as well as other water quality parameters, low maintenance, and cost-effectiveness, the intermittent slow sand filtration was thought to be an effective and feasible alternative for agricultural reuse of reclaimed water. This paper is a preliminary result from pilot study and further investigations are recommended on the optimum design parameters before full scale application.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.4
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• pp.483-491
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• 2008

The filtration characteristics of $CYBAGFILTER^{(R)}$ unit with pleated filter bags were evaluated by comparing the performance of the unit with the lower part of cyclone shape with that of the unit with conventional lower part. Results from the test were also compared with those from the previous research with the $CYBAGFILTER^{(R)}$ in which round filter bags were installed. $CYBAGFILTER^{(R)}$ is the unit which combines the centrifugal separation mechanism and the fabric filtration mechanism in a single unit for efficient removal of particulate matters. The pleated filter bags are made of pleated fabric with an extension of the filtration area about 3 times compared with the conventional round filter bags. The results from the test using pleated filter bags showed an overall collection efficiency of over 99.9% regardless of the shape of lower part installed. When the lower part of cyclone shape was installed, the filter cleaning interval was over 2 times longer compared with that when the conventional lower part was installed. At the same conditions of filtration velocity and filter pressure drop, the $CYBAGFILTER^{(R)}$ with the lower part of cyclone shape, in which the pleated filter bags are installed, can be operated with a flow rate of round 3 times higher than that with conventional round filter bags.

• Journal of Environmental Health Sciences
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• v.47 no.3
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• pp.292-301
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• 2021

Objectives: Wearing medical masks has been recommended since the declaration of coronavirus disease-19 (COVID-19) as a pandemic disease. Certified medical masks are evaluated according to filtration efficiency and facial inhalation resistance. However, some people use non-certified common masks. This study aimed to evaluate various non-certified commercial masks based on the certification criteria for medical masks. Methods: Twenty mask products (three anti-droplet, three disposable dental, eight fashion, three cotton, and three children's masks) were selected. For performance evaluation, filtration efficiency and facial inhalation resistance tests were conducted. The evaluation method followed the certification method for KF-certified masks of the Ministry of Food and Drug Safety (MFDS) and the N95 respirator of the National Institute for Occupational Safety and Health (NIOSH). Results: None of the 20 masks met the KF94 certification standard set by the MFDS. Four and three masks respectively met the KF80 certification standard and the N95 standard of NIOSH. Filtration efficiency was significantly higher in three-layer masks than in single layer masks. Pleated-type masks had higher filtration efficiency than cone-type masks. There was no correlation between the structure of masks and facial inhalation resistance. Conclusion: While no masks complied with the KF94 certification standard, a few masks met the KF80 and the N95 certification standards of NIOSH. Although some people wear non-certified commercial masks, protection from aerosols is not guaranteed by such masks. Evaluation of the protection efficiency of non-certified mask against microbiological infection is needed for the prevention of infectious disease.