• Particle and aerosol research
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• v.15 no.4
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• pp.173-182
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• 2019

Since airborne viruses have been known to aggravate indoor air quality, studies on the development of anti-viral air filter increase recently. In this study, the pressure drop and anti-viral efficiency of TiO₂ coated ceramic ball filter were evaluated. After the filter being inserted into a commercial room air cleaner, chamber test with aerosolized bacteriophage MS2 was performed. The porosity of TiO₂ coated ceramic ball filter was 0.85, and pressure drop was about 13 Pa for 1 m/s of air velocity. The anti-viral efficiency was about 93% when the reaction time was 25 minutes in a 1 ㎥ chamber.

• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.499-503
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• 2008

In order to control the non-point source pollution, a vegetative filter strips (VFS) was set up and the site-monitoring was performed. The objective of this study is to investigate the influence of the plant coverage on treatment efficiency of total nitrogen (T-N) and total phosphorus (T-P) using vegetative filter strips. According to the results, it seemed that the treatment efficiencies of T-N and T-P were closely related with the plant coverage ratio. The results showed that treatment efficiency of T-P average 50% at higher than 50% of the plant coverage and 20~23% at lower than 50% of the plant coverage. Also, the treatment efficiency of T-N increased with the increase of the plant coverage ratio.

• Particle and aerosol research
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• v.5 no.1
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• pp.9-16
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• 2009

Pressure drop and particle removal efficiency of two commercial fibrous medium filters were measured with 20~1,000 nm sized aerosolized KCl particles. Pressure drop and particle removal efficiency were also theoretically predicted and the results qualitatively agreed with the experimental data. For this given particle removal efficiency, a filter design method for obtaining minimum pressure drop (and therefore minimum fan power) was suggested in this study by selecting solidity and fiber diameter as parameters. Therefore, by carrying out theoretical and experimental approaches together, this paper introduced a way of finding conditions for low pressure drop and high performance of a fibrous filter, especially if the filter would be used in mechanical ventilation system.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.2
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• pp.41-46
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• 1999

Backwashing is an important process for the efficient operation of granular filters, and the efficiency of the surface washing among the backwashing processes can affect the filtrations rate and filter run-time. In this study, the efficiency of surface washing is evaluated using real filters for three cases: with surface washing (with and without drainage of water to the surface of filter bed) and without surface washing. As a result, in the case of adopting both the drainage and surface washing, the filter of which condition is initially worse than those of the other filters shows improvement in head-loss development, filtration velocity, filter run-time, and total filtration volume. On the other hand, the conventional method of surface washing rarely has an effect on the filter washing.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.453-455
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• 1995

In electrostatic airclean filter, the collection efficiency defends on particle charge in the ionizer section. The effect of electrostatic airclean filter condition (deposition of dust, variation of corona discharge current) on corona discharge characteristics was well studied. However, it seems not to be studied on corona discharge characteristics of electrostatic airclean filter respect to contaminated electrode which is caused by practical use. In this paper, Long-term(60days) effects are studied experimentally by two methods. The one is ozone concentration, the other is collection efficiency. Generation of ozone level was increased but collection efficiency was slightly reduced in long-term used electrostatic airclean filter.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.975-980
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• 2002

We actually installed antibacterial air filter on the air intake route to air conditioner in passenger car and evaluated filters performance on antibacterial effect. And also, antibacterial effect was observed at whole are of filter media by zone of inhibition test. In the evaluation of antibacterial test, it was shown that the air filter has notably sufficient antibacterial efficiency against ordinary filter.

• Particle and aerosol research
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• v.6 no.4
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• pp.185-192
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• 2010

This paper reports that the installation of a carbon fiber ionizer in front of an activated carbon fiber(ACF) filter enhanced the antibacterial efficiency. In addition, the effect of the ionizer on the filtration of bioaerosols is reported. Negative air ions from the ionizer were used as antibacterial agent. The test bacteria(Escherichia coli) were aerosolized using an atomizer and were deposited on the ACF filter media for 10 minutes. E. coli deposited on the filter were exposed to negative air ions for 0, 1, 5 and 10 minutes. Then they were separated from the ACF filter by shaking incubation with nutrient broth for 4 hours. The separated E. coli were spread on nutrient agar plates and incubated at $37^{\circ}C$ for 1~3 days. The antibacterial efficiency of E. coli was measured using a colony counting method. The antibacterial efficiencies of E. coli exposed to negative air ions for 1, 5 and 10 minutes were 14%, 48% and 71%, respectively. The filtration efficiency was evaluated by measuring the number concentration of bioaerosols at the upstream and downstream of the filter media. The increase of filtration efficiency by air ions was 14%, that is similar to the 17% filtration efficiency by none air ions. The ozone concentration was below the detection limit (under 0.01ppm) when the carbon fiber ionizers were on.

• The KIPS Transactions:PartC
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• v.19C no.3
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• pp.173-178
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• 2012

Recent two security schemes showed that a bloom filter can reduce a message length required for representing multiple MACs. The schemes, however, made message length comparison without considering security level. Since the MAC is intended for security, it is important to let multiple MACs and the bloom filter have the same level of security for making message length comparison. In this paper, we analyze the message length efficiency of bloom filter, compressed bloom filter and multiple MACs, letting them have the same security level.

• Journal of Environmental Science International
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• v.8 no.4
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• pp.473-477
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• 1999

The purpose of this study was to investigate the characteristics of removal efficiency for aromatic hydrocarbons using a high-temperature fiber filter on a laboratory scale. The main elemental compositions of a high-temperaure fiber filter are aluminium and silica, which can act as the catalysts. Benzene, toluene and o-xylene among aromatic hydrocarbons were used in this experiment. For 3cm thickness of fiber filter, these compounds were removed more than 90% at the face velocities of 3cm/sec and 5cm/sec above 45$0^{\circ}C$. For 4cm thickness of it, the removal efficiencies of these compounds were almost 90% from 40$0^{\circ}C$ at the same face velocities, suggesting that it may be due to increasing the contact time between the fiber filter and aromatic hydrocarbons. The pressure droop ranged from 22 to 48mmH2O for 3cm thickness of fiber filter. However, for 4cm thickness of it, it was about two times(41~89mm$H_2O$) higher than that for 3cm fiber thickness.

• 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.