• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.6
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• pp.145-152
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• 2011

In order to heat greenhouse nearby river channel, riverbank filtration water source heat pump was developed for getting plenty of heat flux from geothermal energy. Recharging well, thermal storage tank with separating insulation plate and filtering tank for eliminating iron, manganese were mainly developed for making the coefficient of performance (COP) of heat pump higher. Heating system using riverbank filtration water source heat pump was installed at a paprika greenhouse in the Jinju region where a single fold of vinyl cover and 2 layers of horizontal thermal curtain were installed as a part of temperature keeping and heat insulation with a greenhouse area of 3,185 $m^2$. 320,000 kcal/h was supplied for performing a site application tests. A greenhouse heating test was performed from Feb. 1, 2011 to Apr. 30, 2011. As the result of that, COPh of the heat pump was measured in the range of 4.0~4.5, while COPS of the system was represented as 2.9~3.3. COP measured of the heat pump was very good and well responded to indoor heating temperature of the environment control system of a greenhouse.

• 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.

• 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.

• Journal of Korea Water Resources Association
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• v.34 no.5
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• pp.459-472
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• 2001

The objective of this study is to evaluate the filtration efficiency of deep-bed filters by comparing to single and dual media filters. Pilot-plant tests using four-filter columns were conducted for the comparison of head loss development and filtered water quality. The dual-media filter showed greater initial head loss, but less rate of head-loss development than those of the coarse-sand-0deep-bed filters. For 180 m/day of filtration rate, the dual-media filter produces larger unit production rate by 30-40%, and the turbidities of filtered water were below 0.1 NTU. The initial breakthrough could be effectively controlled by the dual-media filter rather than coarse-sand-deep-bed filters.

• Journal of the Korean Geosynthetics Society
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• v.5 no.2
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• pp.31-37
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• 2006

The purposes of this paper are to study the use possibility of geotextile tubes for dewatering of high water content sludges and sediments and to evaluate affecting factors on dewatering. To do this, pressure filtration tests are conducted on four high water content materials with two geotextiles under two filtration pressures. Based on the test results, although woven geotextile tubes are not satisfied the soil retention criteria used in filter design commonly, a great portion of fines are retained by filter cake formation on geotextile tube's upstream side, but also after formation of filter cake, the permeability drops sharply. Higher filtration pressure tends to increase dewatering rate, but has very little effect on filtration efficiency. Dewatering capacity is affected by several factors which are related to the geotextile, but the property of sludge appears to be the dominant control factor for dewatering efficiency.

• Journal of environmental and Sanitary engineering
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• v.6 no.1
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• pp.7-25
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• 1991

Until now, pure drinking water grnerally menas the water without taste, odor, general bacteria, coliform, and other exotic substance. Such a definition has been changing recently due to the finding of numerous other inorganic and organic substances unknown to us. 10 years ago, major causes of death were infectious agents and parasites contained in water, but recently, it has become apparent that some substances contained in drinking water cause cancer and heart diseases. We must drink about 2L of water everyday in order to maintain healthy condition. Waters used for drinking include tap water, well water, spring water, filtered water, etc., but the quality of drinking water has more polluted due to the industrial development and population increase. For example, industrial waste waters from industrial plants pollute the water supply sources ; toxic substances contained in the waste waters pollute the ground water sources by penetrating the geological strata, and municipal, livestock, public building waste waters also pollute the water supply sources. Sometimes, the polluted surface waters were announced to be polluted by various kinds of orgainc substance, and it is reported that the pollution of ground water by orga nic substances has few in number but high in its concectration comparing with those of surface water. As the water quality pollution level increases, so the amount of disinfectant also increase. For example, chlorine solution, one of widely used disinfectants, creates trihalomethane(THM), a carcinogen, and halogen compounds. According to Oliver, through chlorine disinfection process, humine substance and chlorine create bolatile organic halide and nonvolatile organic halide by chemical reaction. There are tens or hundreds filtering devices, but filtering principles and maintenance metjhods are different, so their efficiency tests are needed. According to Smith, the effeciency tests aginst over 30 Ameican filtering devices show that 10 devices can remove 85% of volatile organics and further studies on filtered waters are underway. In consideration of important impacts of polluted drinking water on national health, authors studied the state of water quality pollution against tap water used as drinking water, filtration device passed water, ground water, and conserved drinking water ; tested the efficiency of filtration devices for tap water ; tried to sep up the detection method by using ion chromatography based on negative ion and positive ion by using single column, and attemped the simple filtration method for general households.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.905-913
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• 2008

The water resource depending on mostly surface water has many problems, such as contaminated and unpredicted contamination event. For this reason, it has been employed highly technical treatment method for them, such as ground water dam and river bank filtration. it has been developed the radial collector wells in kind of bank filtration to increase efficiency for in-taking the water resource insead of the vertical well needed many wells to take more resource. But it has many problems with the incumbent method to bore the horizontal hole for radial collector wells, such as filling with the filter material outside of a strainer by watering, jamming as retrieving the casing tube with the filter material, eccentric boring etc. To reduce the problems of incumbent equipment, it has been developed the horizontal boring equipment and performed the field trial tests several times, which have bits and water jetting system with rotating the cone-shaped front to be excavated easily. In this paper, it was compared the brand-new with the incumbent non-rotating pressing insertion method. Also it was shown the problems of the incumbent method was reduced effectively.

• Proceedings of the Membrane Society of Korea Conference
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• 2001.07a
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• pp.155-162
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• 2001

Advanced drinking water production systems, which not only good quality product water, but also provide easy management and mainenance of facilities, and operate on a smaller site area, have been expected to be developed for some time. We are going ahead with a program to deveop an advanced drinking water production system, using immersed membrane filtration combined with biological activated carbon, to meet the need described above. The demonstration plant tests been conducted with surface water from the Yodo-river since Dec. 1998 to measure treatment performance, reliability, and controllability of the system. The quality of product water has consistently remained at a very high level for about 2 years under controlled conditions. Results showed that the re-circulation granular biological activated carbon could suppress the increase of membrane pressure difference and promote a reduction of dissolved organic matter. (This work has been conducted along the ACT21 Programs.)

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.321-327
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• 2006

This interlaboratory study was designed to evaluate protozoan test methods in water and to predict the major causes of deviation of the methods. Each of four laboratories with previous experience of protozoa analysis in water participated, and met the initial performance criteria of EPA 1623 method provided. The protozoan analysis procedure consists of filtrations, concentration, immunomagnetic separation, dyeing (staining) and counting with observation. We tested three different filtration equipments: capsule filter for 10 L of surface water, and high volume (HV) capsule filter and membrane filter for 100 L of finished water. When the recovery of each step of the procedure was evaluated with EasySeed, the commercial stock of each 100 Cryptosporidium and Giardia, immunomagnetic separation and filtration step were the most crucial steps affecting the stability of the recovery, especially for Cryptosporidium. There was no significant difference of recovery among the filtration methods. Recovery of protozoa from source water were evaluated with spiked EasySeed as matrix tests. The recoveries of Giardia increased significantly in the matrix tests compared those in the deionized water. We also applied red stained mixture stocks of Cryptosporidium and Giardia called ColorSeed as internal standards of water sample tests. The recoveries of both EasySeed and ColorSeed in samples tested were within the range of the criteria, however, the Giardia recoveries using ColorSeed decreased significantly. Further optimization study with ColorSeed will be necessary, considering the convenience of using the internal standard without additional sample analysis. The significant factors of the recovery variation were identified as the differences of laboratories as well as water quality and type of the stock for spiking. The results of this study emphasize the importance of the quality assurance program for protozoan analysis lab in water.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.179-182
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• 2002

Geosynthetics are widely used in landfill for filtration, drainage, separation and so on. For many landfill failure cases, interfaces of geosynthetics can be potential failure surfaces. Therefore, it is very Important to estimate the interface properties of geosynthetics. In this study, shaking table tests were peformed between smooth geomembrane and geotextile. From the test results, it was found that there is a limited acceleration that can be transmitted from smooth geomembrane to geotextile. And the influence of normal stress and frequencies of excitation were discussed.