• 상하수도학회지
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• 제22권4호
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• pp.461-466
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• 2008

Because of their simplicity, efficiency, and economy, slow sand filters are appropriate means of water treatment for small water systems. In this study, the effect of filtration velocity and dirty skin (Schmutzdecke) was evaluated on the performance of turbidity removal. Also, removal characteristics of particulate were investigated in the case of the usage of non-woven fabric on the surface of sand and the application of PCF as pretreatment process. Comparative column tests were carried out for the various operation condition. From the result of column tests, filtration velocity had little effect on the turbidity removal rate. The formation of algal biofilm on the surface of media is helpful in turbidity removal, while non-woven fabric is not as effective as expected. The relative contribution of biomass and accumulated particulates to head loss development in slow sand filters requires further study.

• 한국환경보건학회지
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• 제41권3호
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• pp.203-215
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• 2015

Objectives: This study was designed to evaluate the filtration efficiencies and pressure drops of five commercial cloth masks (4 plate type, 1 cup type) in comparison to the performance of a class 1 disposable respirator (reference respirator). A further objective was to evaluate the effects of the number of layers and wash treatment independently on filtration efficiencies and pressure drops. Methods: Polydisperse NaCl aerosols were generated in an aerosol chamber and their concentrations were measured by an optical particle counter (OPC) in the size range of $0.3{\sim}10{\mu}m$ (five channels). Results: The filtration efficiencies of the five cloth masks and the reference respirator were D: 9.5%, C: 18.5%, E: 23.6%, A: 28.5%, B: 29.7% and R: 91.1%, respectively, and the pressure drops through them were C, D: 0.8 Pa, E: 1.7 Pa, B: 6.4 Pa, A: 42.7 Pa and R: 19.3 Pa, respectively. The filtration efficiencies of the cloth masks and reference respirator were below the class 1 respirator criterion (${\geq}94.0%$) of the Ministry of Employment and Labor (MOEL) and Ministry of Food and Drug Safety (MFDS). The pressure drops satisfied the class 1 respirator criterion (${\leq}70Pa$) of MOEL and MFDS. When the cloth masks were folded into two and four layers, the filtration efficiencies of cloth masks A, B, C, D (plate type) increased 1.7-4.6 times, and 2.3-6.8 times, respectively, compared to the efficiencies of the same products in a single layer. Pressure drops increased as the number of layers was increased. The filtration efficiency of cloth mask E with a liner was 1.3 times higher than that of the same mask without a liner, and the pressure drop was lower in the no-liner configuration. After a single washing, the filtration efficiencies of all the cloth mask products decreased 1.04-4.0 times compared to those of the same products intact. For the cloth masks C and E, their filtration efficiencies were significantly decreased after washing (p<0.05). The pressure drops of all cloth masks were 1.2-2.0 times lower after washing. Conclusions: The filtration efficiencies of the five cloth masks were below 30% and did not improve greatly by increasing the number of layers. After a single washing, their performances decreased. Considering the above and other issues identified with cloth masks, such as poor fit and stretched fibers through use, people should not expect protection against particulate matters from the cloth masks on the market.

• 한국입자에어로졸학회지
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• 제8권4호
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• pp.133-141
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• 2012

A new depth filter media was designed and samples of flat sheet as well as cartridge assembly were prepared and tested to evaluate the filtration performance and compare with the commercial product. The arrangement of the depth filter media layers is important to reach the optimal filtration parameters like filter pressure drop, particle collection efficiency and dust holding capacity. Initially, both flat sheet samples of new media and commercial product have been tested using standard test units. Tests with new depth filter media cartridges of various pleat count were conducted in order to find the optimal pleat count which would represent the lowest pressure drop. These tests give an insight on how the pleat count and the assembly configuration affect the performance of the depth filter media cartridge. By comparing the samples with a commercial product we could confirm relatively high filtration performance of the sample cartridge with pleat count 150 made of new depth filter media. The cartridge with the same pleat count exhibits better performance without the outer mesh.

• 한국지반신소재학회논문집
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• 제6권1호
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• pp.33-38
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• 2007

연직배수재는 필터와 코어로 형성되며, 필터의 주요기능으로 첫째, 흙 입자의 유실을 방지할 수 있는 흙 보유성과 둘째, Clogging 또는 Blinding현상 발생 없이 간극수를 원활히 배출시키는 투수성을 갖추어야 한다. 상대적으로 투수성이 낮은 지반에서 미세입자로 인하여 필터의 투수성을 저하시키는 필터폐색(Clogging) 현상이 발생하는데 필터의 폐색현상(Clogging)이 점진적으로 증가하면, 간극수의 흐름을 저하시켜 결국 압밀지연을 초래한다. 지반-필터의 거동에 따른 설계(시방)기준은 토목섬유 필터의 간극크기와 흙의 입도의 상관관계에 의해 결정되어야 하나, 국내에서는 필터폐색(Clogging)현상과 지반-필터의 거동 분석 없이 필터재의 유효입경(AOS, Apparent Opening Size)만을 고려하여 필터의 설계(시방)기준을 일률적으로 적용하고 있다. 따라서, 본 연구에서는 3가지 종류의 연직배수재 필터를 대상으로 필터의 거동 및 필터폐색(Clogging)현상을 평가하고자 실내시험을 수행하였고, 이를 토대로 ${\bigcirc}{\bigcirc}$지역에서 연직배수재 필터의 설계(시방)기준을 선정하여 적용하였다.

• 한국산업보건학회지
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• 제32권1호
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• pp.53-63
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• 2022

Objectives: This study was designed to evaluate the filtration efficiency, inhalation resistance, and liquid resistance of commercial reusable masks in comparison to the performance of KF-AD masks (reference masks). Methods: Thirty-six masks were purchased from an online market. Filtration efficiency and inhalation resistance were determined in the same manner as in MFDS certification testing, respectively using TIL/IL & Filter Test 1300S (SFP Services, UK) and Breathing Resistance Analyzer DA2001 (Lambda Ray, South Korea). Results: Most of the filtration efficiencies found for the 19 masks were far lower than the test standard for KF-certified masks. Four masks met KF94 and three masks even met KF80. Most inhalation resistances were also much lower than the standard, with many almost one-half of the standard. In addition, all the masks except KF-AD masks did not pass the liquid resistance test. Conclusions: Although most of the filtration efficiency performance results found in this study for the reusable masks, which emerged as an alternative, were lower than the standard for health masks, multi-use masks can be used with a replacement filter inserted.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2010년도 춘계학술대회 논문집
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• pp.149-150
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• 2010

• 한국물환경학회지
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• 제21권5호
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• pp.458-463
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• 2005

Considering the characteristics of a filtration bio-reactor equipped with a mesh filter module which can effectively maintain high concentration of biomass and enhanced solid-liquid separation performance, the hybrid process of filtration bio-reactor combined with coagulation was investigated to get improved filtration characteristics as well as water quality in this work. Two bio-reactors (Run-1 & Run-2) were operated under the following conditions: working volume of 25 L, continuous loading of a synthetic wastewater (BOD: 200 mg/L, T-N: 50 mg/L, T-P: 5 mg/L), where an appropriate amount of alum ($Al_2(SO_4)_3{\cdot}18H_2O$) was added once a day into the reactor (Run-2). In the system without using a alum (Run-1), the clogging of mesh filter module was observed two times through 85 days of whole operation. Meanwhile, the filter module did not clog even at higher MLSS concentration (6,000~12,000 mg/L) and the stable filtration (0.7 mid) was continued in the case of using a alum. Due to the stable formation of cake layers, BOD and SS were shown below 6 and 3 mg/L, respectively. T-P and pH of the effluent were changed because of the intermittent addition of the alum. In the case of Al/P=2.5, the average T-P removal efficiency per day was 85.2% and the average T-P concentration of the effluent was 0.3 mg/L. However, the removal efficiency of phosphate was influenced by pH in the reactor.

• 상하수도학회지
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• 제23권2호
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• pp.215-222
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• 2009

This study compares the performance of the filters with various media in pretreatment of seawater desalination by reverse osmosis. For this purpose, Masan bay seawater is used as raw water. The filter performance is evaluated by the filtrate quality and the head loss development. Five media is selected in this study: anthracite, $Filtralite^{(R)}$, sand, Pumice, $AFM^{(R)}$. These media are used in combination for dual media filter and alone for mono media filter. The comparison results show that NC0.8-1.6 is the best $Filtralite^{(R)}$. The dual media filter of NC0.8-1.6 and sand outperformed other filters in particle removal. The dual media filter of anthracite and sand showed good performance in organic removal. The mono media filter of Pumice produced the similar filtrate quality as the mono media filter of sand although the effective size of Pumice is considerably greater than that of sand. Due to big size, head loss development is maintained slow in the filtration of Pumice.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.151-152
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• 2012

Collectors connected to diesel engine exhaust pipe for application of PM reduction facilities which was used to reduce PM from the exhaust gas produced from ship, Filtration performance of PM was tested. In this system, it was confirmed that the bag house can remove over 90 percent of PM from a lot of high temperature and high pressure gases produced in diesel engine. The results obtained from performance test show the potential possibility for commercialization of ceramic filter collectors which is applied to reduction facilities of flue gas produced from a diesel engine on the ship.

• KSBB Journal
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• 제15권1호
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• pp.76-79
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• 2000

Complex, ill-defined mixtures of natural origin are often used as nutrients in the production of biological products through microbial fermentation. Product yields are affected by variation in these natural products. Yeast extract is a typical example of these natural products. Since it is a mixture of amino acids, peptides and nucleic acids, its composition is not well characterized. In this study, we investigated the properties of thiamine hydrochloride, riboflavin and pyridoxine hydrochlride in yeast extract by using a gel filtration chromatography, ion exchange chromatography and high performance liquid chromatography. Yeast extract solution was fractionated by gel filtration chromatography and ion exchange chromatography, and then, each fraction was analyzed by using a high performance liquid chromatography.