• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.126.1-126
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• 2003

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.10
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• pp.1044-1049
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• 1990

This paper is concerned with a ceramic filter laminated in the order of piezoelectric vibrator/that insulator/piezoelectric vibrator, and introduces general expressions near the resonant frequency, related with electrical inputs and outputs, gain and phase difference between input and output voltages, resonant frequency, and bandwidth, when the electrodes of the output element are divided by n equi-sections. This paper also shows that those expressions describe well the related experimental phenomena when n=1.

• Clean Technology
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• v.24 no.1
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• pp.27-34
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• 2018

Catalytic filter has many advantages for the industrial application owing to its bi-functional ability to treat nitrogen oxides and particulate simultaneously. The technical feasibility of using the catalytic filter in the flue gas treatment process will be more promoted if the high porous ceramic sheet filter is utilized. However, it is not easy to prepare the effective catalytic filter using sheet filter as it has less room for catalyst support due to its thin layer. In this study, catalytic filter using a domestic ceramic sheet filter element has been prepared and conducted the experimental evaluation for NO reduction performance. The current sheet filter element shows the low catalytic activity less than 92% conversion for NO concentration 700 ppm at the face velocity $0.02m\;s^{-1}$. This unexpected low catalytic activity seems to be caused by the present of extraordinary large pores from the lack of uniformity in the pore size distribution of the sheet filter. The large pore size of the sheet filter is reduced by composing the smaller powder as its raw material, which presents improvement in NO conversion more than 96%. More improvement is observed showing 98% NO conversion which is applicable to a commercial plant when the catalyst coating layer is expanded by adding the large $TiO_2$ particles during the catalyst preparation. Both of above two methods is regarded as that the broad gates of the larger pores in the coating layer are effectively filled with the proper catalyst. So these results encourage the utilization of sheet filter as a good catalytic filter material with its potential merit of high permeability.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.3
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• pp.291-302
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• 2004

The CuO/$3AL_2O_3{\cdot}2SiO_2$ catalyst impregnated ceramic candle filters for nitrogen oxides removal were prepared by porous mullite($3AL_2O_3{\cdot}2SiO_2$) support and CuO catalyst deposited on this support to achieve uniformly dispersed CuO deposition, which are impregnated into the pores of available alumino-silicate ceramic candle filter. The CuO/3$AL_2O_3{\cdot}2SiO_2$ catalyst impregnated ceramic candle filters were characterized by XRD, BET, air permeability, pore size, SEM and catalytic tests in the reduction of NOx by NH$_3$. The observed effects of CuO/3$AL_2O_3{\cdot}2SiO_2$ impregnated ceramic candle filters in SCR reaction are as follows : (1) when the content of CuO catalyst increased further, activity of NO increased. (2) NO conversion at first increased with temperature and then decreased at high temperatures (above 40$0^{\circ}C$), possibly due to the occurrence of the ammonia oxidation reaction. (3) In pilot plant test for 3 months, NO conversion was greater than 90%.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.406-412
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• 2014

In this study, flat-tubular-type alumina filters were manufactured using alumina powder of two sizes ($2.4{\mu}m$ ALM-44 and $0.4{\mu}m$ AP 400) by an extrusion process. The manufactured alumina filter was sintered at $1200-1600^{\circ}C$ for 1 h. As particle size increased, the largest pore size, average pore size and porosity increased; but density and linear shrinkage decreased. The alumina filter fabricated using ALM-44 powder sintered at $1500^{\circ}C$ was confirmed as the best water treatment filter after investigation of the bending strength, water permeability and impurity-removal efficiency of the experimental filters. This flat-tubular-type alumina filter is expected to be useful not only for direct water treatment, but also for use as a support filter during coating processes, to control pore size.

• 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 Korea Foundry Society
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• v.36 no.6
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• pp.208-214
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• 2016

Casting defects, which are closely related to entrapped air bubbles and metallic oxides, occur very frequently in the casting process. Many researchers have shown that these defects can be reduced by adopting an appropriate gating system design. But, it is difficult for field engineers to identify a specific gating system that is more appropriate for their products. In this study, we tried to draw a comparison of gating system designs with and without ceramic foam filters. A ceramic foam filter was added to the horizontal runner just after the sprue to prevent air bubble generation and to reduce turbulence without change of the gating system design. To verify the effects of initial pouring velocity, the experiment was conducted with four different amounts of water volume in the reservoir. Results of the water modeling experiment applying the filter showed remarkably changed flow characteristics. Although the study confirmed that use of the filter may change the flow characteristics, it needs to be noted that only filter use alone cannot solve all the problems caused by a poorly designed gating system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.1
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• pp.13-20
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• 2010

Airborne particulate matters have two modes of size distributions of coarse mode and fine mode. The coarse mode which is formed by break down mechanism of large particles has a peak around the $100\;{\mu}m$, and the fine mode formed by condensation and build up mechanism of evaporated vapors has a peak at several ${\mu}m$. The coarse mode particles can be removed easily by conventional collecting equipments such as a cyclone, an electrostatic precipitator, and a filter, however the fine mode particles can not be collected easily. Usually the fine mode particles are generated in the high temperature conditions especially through boilers and incinerators, so the high efficient and temperature filter is essential for the filtration. In this study, a nano ceramic filter for the removal of fine particles in the high temperature is developed and tested for several characteristics. The nano ceramic filter has double layer of micro and nano structure and the pressure drop and the filtration efficiency for $0.31\;{\mu}m$ at 3 cm/s are 15.45 mmAq, and 96.75%, respectively. The thermal conductivity is $0.038\;W/m{\cdot}K$, and the coefficient of water vapor permeability is $3.63\;g/m^2{\cdot}h{\cdot}mmHg$. It is considered that the sensible heat exchange rate is very poor because the low thermal conductivity but it has high potential to exchange latent heat.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.2
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• pp.91-95
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• 2008

Ceramic filter was prepared using cordierite powder and it was coated with $V_2O_5$ catalyst by vacuum impregnation method. The filter had the apparent porosity of 58 %, the compressive strength of 10 MPa and the pressure drop of 1200 Pa at the face velocity of 5 cm/see and 400$^{\circ}C$. $NO_x$ removal efficiency of only $V_2O_5$ coated on cordierite filter showed the removal efficiency of 80 %, and it was improved up to 90 % by increasing specific surface area of filter elements from the acid treatment. The high surface area is due to the removal of Mg and Al ions from the silicate structure and subsequent generation of free amorphous silicate on the surface of the cordierite.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.32-39
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• 2005

When PFC(Perfluorocarbonate) decontamination technology is applied to removal of radioactive contaminated particulate adhered at surface during the operation of nuclear research facilities, it is necessary to develop a filtration equipment to reuse of PFC solution due to high price, also to minimize the volume of second wastewater. Contaminated characteristics of hot particulate was investigated and a filtration process was presented to remove suspended radioactive particulate from PFC decontamination wastewater generated on PFC decontamination. The range of size of hot particulate adhered at the surface of research facilities measured by SEM was $0.1{\sim}10{\mu}m$. Hot particulate of more than $2{\mu}m$ in PFC contamination wastewater was removed by first filter and then hot particulate of more than $0.2{\mu}m$ was removed by second filter. Results of filter experiments showed that filtration efficiency of PVDF(Poly vinylidene fluoride), PP(Polypropylene), Ceramic filter was $95{\sim}97\%$. A ceramic filter showed a higher filtration efficiency with a little low permeate volume. Also, a ceramic of inorganic compound could be broken easily on experiment and has a high price but was highly stable at radioactivity in comparison of PVDF and PP of a macromolecule which generate $H_2$ gas in alpha radioactivity environment.