• Environmental Engineering Research
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• v.7 no.2
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• pp.85-92
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• 2002

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2010.03a
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• pp.186-186
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• 2010

• Proceedings of the Membrane Society of Korea Conference
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• 2000.04a
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• pp.59-62
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• 2000

• 월간산업보건
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• s.257
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• pp.59-60
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• 2009

• Clean Technology
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• v.8 no.3
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• pp.141-149
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• 2002

In the present study, flow fields inside a photocatalysis air cleaning system have been investigated to obtain the data for optimum design of the system. For this investigation, we first predicted the pressure drop of a photocatalysis filter. Based on this calculation, we replaced the filter by the porous media and analysed the performance of the entire system. This porous media assumption could predict characteristics of the cylindrical photocatalysis filter within 1%. Two cases of the cylindrical filter were considered in the present calculations. The first case had an inside diameter of 6 mm, while the second case had an inside diameter of 20 mm. It was found that the first case of filter showed a pressure drop three times higher than that of the second case. In addition, the cylindrical filter equipped with a housing to hold a number of cylinders in a bundle was also analyzed. When the housing was present, the pressure drop increased. It was found that the pressure drop is 8 times higher than that of the case when the housing was not equipped.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.558-562
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• 2006

Filtration experiments were conducted to determine the characteristics of manganese removal in filtration using 4 different filter media including sand and manganese sand(MS). Filtration velocity was 123 m/d and the flow rate was $3.9m^3/d$ per column. Duration of these experiments was about one year, and manganese dioxide accumulation, turbidity removal, manganese removal, and organic material removal were examined depending on filter media. When filter influent(residual chlorine 1.0 mg/L) with an average manganese concentration of 0.208 mg/L was fed through a filter column, the sand+MS and MS columns removed 98.9% and 99.2% of manganese respectively on an annual basis. When there is need to replace the sand filters with a MS filter to remove manganese, it was shown that the replacement of a partial sand filter with MS had adequate manganese removal.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.16-24
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• 2005

Mathematical model was developed to verify a sequential particle removal taking place in a granular media gravity filter. Consequential multi-layer filtration cycle model was applied to verify the fraction of filter effluent particles that are filter influent particles that were never removed as well as the fraction of filter effluent particles that were detached after deposition were performed through laboratory experiments. Three sizes of marker particles were injected ahead of the filter column as a pulse in the presence of four sizes of polystyrene particles that were used as a primary source of particles in the raw suspension to investigate particle attachment alone in contrast to net removal from attachment and detachment. Microscopic counting of filter effluent particles was assumed to reflect attachment. Experimental results indicated that particle detachment is significant beginning from the early phase of filtration. For each size of fluorescent microspheres at one filter depth, fluorescent microsphere removal increased with filter runtime to a maximum due to ripening. The detached fraction of effluent particles increased with particle size and filter depth. The presence of detached particles and the increasing fraction of detached particles in deeper bed were confirmed.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.6
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• pp.675-687
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• 2012

Applying an external electric field across air filter media is one of methods to improve the filtration performance. Metal wire meshes have been commonly used as electrodes situated on both sides of a thick filter pad. For a thin filter medium a short circuit, known as the biggest drawback for applying an external electric field to air filter, can occur at the closest point between electrodes. In this study several types of insulated meshes were prepared by coating #50 meshes with a dielectric material, Nylon 66, and the filtration property of air filter was evaluated at the presence of external electric field using those insulated meshes as electrodes and compared with that of filters using bared meshes. The collection efficiency of tested filter was increased from 78% to 95% for singly charged 100 nm particles by application of external electric field. As a result, there was no significant difference in collection efficiency between filters with insulated and bared electrodes. Similar results could be also seen from the tests using polydisperse particles. Finally, through this study, we found that the insulation of mesh electrodes doesn't affect the filtration performance of fibrous air filter under external electric field.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.11a
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• pp.39-43
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• 1997

본 논문에서는 ActiveMovie와 같은 stream data 기반의 library에서 실시간으로 사용될 수 있는 영상 특수효과 filter들을 소개하고, 알고리즘 개발 및 구현방법에 대해 기술한다. ActiveMovie는 기본적으로 mpeg decoder 및 Video for Windows(.avi file) decoder를 제공하여 프로그래밍을 수월하게 한다. 또한 각 module에 filter라는 개념을 도입하고 filter graph라는 구조를 이용하여 filter의 추가, 삭제를 용이하게 한다. 본 논문에서는, 디지털 영상 특수효과 중에서 Mosaic, Wind, Ghosting 등의 point processing filter들을 실시간으로 처리하기 위한 고속의 알고리즘을 제안한다. 제안하는 알고리즘은 픽셀의 포인터를 특정 위치로 이동시키지 않고 단순히 주소값을 하나씩 증가시키는 연산을 이용하여 실시간 특수효과를 얻을 수 있도록 한다. 또한 이와 같은 특수효과 알고리즘들을 ActiveMovie환경에서 구현함으로써 제안된 기법에 의하여 실시간 동영상 특수효과 처리가 가능함을 입증한다.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.77-85
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• 2009

As the multimedia technology has become in popular, many software packages that are for using those multimedia contents have also been developed. Directshow is a media framework which makes the development of such multimedia software simple, quick and regular process. In the Directshow, data are processed through the connections between filters. In general, Filtergraph is utilized to be set as 'Intelligent Connection' for filter connection. However, when we use this 'Intelligent Connection' option, they can show non-expected results or fail to connect with filter's pins together. So in this paper, we propose non-necessary filter cut-off method for connecting only just wanted filters. There are two methods such as inner filter cut-off method and outer filter one. The inner filter cut-off method is good at connection's compatibility and able to quickly connect with each other filter. But in the outer filter cut-off method, filter source is not necessary and connection is exactly done with other filter. In the end, we propose Directshow based filter cut-off model which compose of wanted filter connection and minimize error probability, through mixing up the advantages of two filter cut-off methods.