• Journal of Korean Society of Environmental Engineers
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• v.37 no.3
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• pp.152-158
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• 2015

This paper investigated the membrane fouling potential at the state of passive adsorption which is no permeation with the test modules on COD (Chemical oxygen demand) loading rates, examined the recovery rate and resistance on membrane fouling by three cleaning manners of hydrophobic membrane in a bioreactor. The results showed that high COD loading led to the increase of extra-cellular polymeric substances and filtration resistance. The permeability resistance from 1st day to 63rd day was getting increased, however, the value of permeability resistance after 63th day during the operation period was almost same level at three COD loading rates, it was due that the biomass adhesion on membrane surface at the state of passive adsorption reached to the critical state. Also, the final recovery rates after three cleaning manners were 78%, 72% and 69% at the COD loading concentrations of 250 mg/L, 500 mg/L and 750 mg/L respectively, and then recovery rate by physical cleaning at Run 2 and Run 3 was decreased after 40th day, it proved that biomass cake, which is not easily removed, was formed on the membrane surface because of high COD loading rate and EPS concentration.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.304-314
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• 2010

This study was carried out to find out potential use of ochre as an agent to reduce phosphorus content in water. Ochre is a by-product from treatment of acid mine drainage (AMD) which is composed mostly of $Fe_2O_3$, $Fe_2O_3{\cdot}H_2O$, $FeO{\cdot}OH$ and $Fe(OH)_3$. Three ochre samples (ochre-H, ochre-D and ochre-S) were collected from three treatment facilities in Gangwon province. Physico-chemical characteristics of three ochre samples including pH, electrical conductivity, total phosphorus, available phosphorus, particle size distribution were analyzed. Scanning electron microscopy (SEM) energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray fluorescence (XRF) analysis were also carried out. In addition, experiments for phosphorus removal from water was performed. Calcium content of ochre-H was higher than that of ochre-D and ochre-S, whereas iron content of ochre-H was lower than that of ochre-D and ochre-S. All the phosphorus in water up to maximum 191,411 mg $kg^{-1}$ per unit mass of ochre was removed with ochre-H. Ochre has immense potential as an agent to reduce phosphorus content in water.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.11
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• pp.790-796
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• 2011

In this study, we measured the concentrations of volatile organic compounds (VOCs) in Shiwha area by using active and passive sampler. We did a comparative analysis of the characteristics of the active sampler and passive sampler. In the case of the passive sampler, the average TVOC concentration of the industrial area was 1.86 times higher than that of the residential area. In the case of the active sampler, the average TVOC concentration of the industrial area was 1.07 times higher than that of the residential area. When using the passive sampler, the concentration of VOCs in the industrial area was noted to be higher than the concentration found in the residential area. However, when we used the thermal desorption tube, the concentration of residential area was higher rather than that of industrial area in some substances such as trichloroethylene, toluene, ethylbenzene, and xylene. Toluene was a larger percentage of the overall BTEX ratio. In case of the passive sampler, the relative ratio of toluene, ethylbenzene, and xylene was higher in the industrial area than in the residential area. In contrast in case of the thermal desorption tube, the ratio of these substances was higher in the residential area rather than in the industrial area. The passive sampling in this study showed an appropriate method to analyze the temporal and spatial concentrations of air contaminants. This assessment would prove to be useful for its observance of standards or epidemical study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.603-608
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• 2018

Although the voltage-applied discharge method is most widely used in the semiconductor and display industries, periodic management costs are incurred because the method causes defects due to the absorption of ambient fine dust and causes emitter tip contamination due to the discharge. The emitter tip contamination problem is caused by the accumulation of fine particles in ambient air due to the corona discharge of the ionizer. Fuzzy ball generation accelerates the wear of the emitter tip and deteriorates the performance of the ionizer. Although a mechanical cleaning method using a manual brush or an automatic brush is effective for contaminant removal, it requires management of additional mechanical parts by the user. In some cases, contaminants accumulated in the emitter may be transferred to the wafer or product. In order to solve this problem, we developed an ionizer for a clean environment that can remove the pencil-type emitter tip and directly ionize the surrounding gas molecules using the tungsten wire located inside the ion tank. As a result of testing and certification by the Korea Institute of Machinery and Materials, the average concentration was $0.7572particles/ft^3$, the decay time was less than two seconds, and the ion valance was 7.6 V, which is satisfactory.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.12
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• pp.1691-1698
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• 2009

The purpose of this study was to investigate the antioxidative and antiallergic effects of persimmon leaf extract. Antioxidative and anti-inflammatory effects of the crude persimmon leaf extract (PLE) and the partially purified persimmon leaf extract (PPLE) were determined in in vitro assays by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion radicals, and 5-lipoxygenase (5-LO) and cyclooxygenase (COX). Total phenols and total flavonoid levels of PLE and PPLE were $230.0{\pm}19.6$ mg/g and $475.5{\pm}38.7$ mg/g, and $34.8{\pm}6.5$ mg/g and $78.8{\pm}3.6$ mg/g, respectively. DPPH and superoxide radical-scavenging activities ($SC_{50}$) of the PLE and PPLE were $23.8{\pm}3.2$ ppm and $10.0{\pm}1.3$ ppm, and $47.6{\pm}3.4$ ppm and $22.4{\pm}3.3$ ppm, respectively. Inhibitory activities ($IC_{50}$) of PLE and PPLE against 5-LO, COX-1 and COX-2 were $77.1{\pm}11.7$, $38.6{\pm}7.0$ ppm, $47.4{\pm}7.7$, $25.3{\pm}6.3$ ppm, and $129.5{\pm}5.5$, $84.5{\pm}2.3$ ppm, respectively. Moreover, two extracts inhibited dose-dependently NO production in LPS-stimulated RAW 264.7 cells, and also effectively inhibited the cutaneous anaphylaxis reaction activated by anti-dinitrophenyl IgE antibody in mice. These results suggest that PLE and PPLE may be useful for phytochemical materials for prevention and treatment of radical-mediated pathological and allergy diseases.