• Journal of Korean Society on Water Environment
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• v.37 no.6
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• pp.458-468
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• 2021

In this study, we investigated the variations of dissolved organic matter (DOM) in an agricultural reservoir during the monsoon period (June to October, 2020) with respect to the organic carbon concentration (DOC), molecular weight distribution, and optical properties. The monsoon period was divided into three phases - beginning storm (BS), during storm (DS), and after storm (AS). Our results showed significant differences in the concentrations and characteristics of DOM during the summer monsoon. The DOC concentrations were decreased after the monsoon, probably due to a dilution effect. In contrast, increasing trends were observed in the specific UV absorbance (SUVA), and relative abundances of humic-like fluorescence and larger-sized compounds. These observations implied that the large-sized and humic-like organic components with terrestrial origins strongly affected the reservoir DOM after the summer monsoon. Meanwhile, biopolymer size fraction, which is associated with algal activity, became more abundant after the monsoon. These results suggest that DOM with autochthonous sources became dominant as a result of the inflow of nutrients into the reservoir after the storm. Spatial changes in DOM within the reservoir were not pronounced as much as the temporal variations. All taken, it can be concluded that the summer monsoon simply led to the decrease of DOM concentrations while the sources and the quality of DOM underwent substantial changes, which may enrich refractory organic matter in the reservoir. This study reveals the importance of in-depth DOM quality monitoring before and after summer monsoon for effective water quality management in agricultural reservoirs.

• Membrane Journal
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• v.19 no.1
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• pp.7-18
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• 2009

In this study, we used the hybrid module that was composed of granular activated carbons (GAC) packing between module inside and outside of tubular ceramic microfiltration membrane for advanced drinking water treatment. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, modified solution was prepared with humic acid and kaolin. We were investigated effect of water-back-flushing time (BT) and water-back-flushing period (FT) to minimize membrane fouling and to enhance permeate flux (J) in the hybrid process, and tried to find the optimal operating conditions. As a result, resistance of membrane fouling ($R_f$) was slightly decreased according to increasing BT. Also, the shorter FT was the more effective to reduce $R_f$ and to enhance J because of frequent water-back-flushing. However, the optimal BT and FT conditions were 10 sec and 8 min respectively when operating costs were considered. Then, the optimal conditions derived from our experiments of modified solution were applied to lake water treatment. As a result, average treatment efficiencies of turbidity, $UV_{254}$ absorbance, and $COD_{Mn}$ were very high as 99.11%, 91.40% and 89.34%, respectively, but that of TDS was low as 30.05%.

• Applied Biological Chemistry
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• v.41 no.7
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• pp.545-549
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• 1998

This study was carried out to improve the storage stability of export peeled-chestnuts using electrolyzed acid-water, because ice-cold tap water generally used to store export peeled-chestnuts grew turbid during the cold chain, decreasing the quality. The changes of pH and turbidity in the electrolyzed water used for storing peeled-chestnuts were investigated. The pH value rapidly changed when stored at $30^{\circ}C$, whereas it very slowly changed at $4^{\circ}C$. This was especially evident by the change in pH from 2.5 to 3.4 of the electrolyzed acid-water after 8 days. In the case of turbidity, closely correlated with the pH change, the electrolyzed water used for storing peeled-chestnuts was very turbid when stored at $30^{\circ}C$, but it was not even until 14 days at $4^{\circ}C$, as evident by the absorbance $(OD_{660})$ of electrolyzed acid-water at pH 2.5 and $4^{\circ}C$ being only 0.01 after 14 days and 0.11 after 35 days. Sensory evaluation, tested by expert panel, of the chestnuts stored in electrolyzed water was not significantly different compared to the control.

• KSBB Journal
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• v.16 no.4
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• pp.332-336
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• 2001

This paper is intended as an application of the biological rope media sedimentation tank using biodegradability of BAC(Biological activated carbon) to the drinking water treatment system for the removal of NOM. The removal of DOC(Dissolved organic carbon), UV absorbance(UV$\_$254/), and turbidity were evaluated under various operation condition of a biological rope media sedimentation tank such as raw water-media process (Media 1), ozonation-media process (Media 2), and ozonation-coagulation/sedimentation-media process (Media 3). The raw water had DOC concentration of 1.3∼3.4 mg/L, UV$\_$254/ of 0.027∼0.039 cm$\^$-1/, and turbidity of 0.3∼4.5 NTU, respectively. The average DOC concentration were 2.2 mg/L in media 1, 1.8 mg/L in media 2, and 1.3 mg/l in media 3 from raw water, respectively. On the other hand, the DOC concentration in conventional sedimentation tank was 1.5 mg/l. Higher removal of the DOC was noted in media 3 than media 1 and media 2. The UV$\_$254/ of the treated water were 0.037 cm$\^$-1/ in media 1, 0.027 cm$\^$-1/ in media 2, and 0.014 cm$\^$-1/ in media 3 from raw water, respectively The UV$\_$254/ in conventional sedimentation tank was 0.014 cm$\^$-1/ which is similar to that of media 3. Average turbidity of the treated water was 1.1 NTU in media 1, 0.9 NTU in media 2, and 0.5 NTU in media 3, respectively. It is expected that the biological rope media sedimentation tank is a good alternative over the conventional sedimentation process from these results.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.1
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• pp.7-14
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• 2006

The antioxidative activity and the related parameters of hot water extracts obtained from 16 medicinal plants were tested. The extraction yield was the highest in Salvia miltiorrhiza Bunge $(36.49\%)$ pH range was $4.00\~5.92$ in all samples. Absorbance at 280 nm was examined to determine aromatic compounds content. The absorbance of $250{\mu}g/mL$ sample was the highest in Prunella vulgaris Linne var. lilacina Nakai (2.872) and below 0.5 in Cirsium maackii, Crataegus pinnatifida Bunge and Zizyphus jujuba Miller. Also, absorbance at 420 nm was high in order of Prunella vulgaris Linne vu. lilacina Nakai (1.312), Zea mays Linne (0.917) and Inula japonica Thunberg (0.725) Total phenolic compounds contents was the highest in Prunella vulgaris Linne var. lilacina Nakai $(5.07{\pm}0.05\;mg/100g)$ and flavonoids contents was 2-fold higher in Salvia miltiorrhiza Bunge $(4.82{\pm}1.16\;mg/100g)$ than the other samples. Electron donating abilities of Zizyphus jujuba Miller, Cornus officinalis Siebold et Zuccarini and Salvia miltiorrhiza Bunge were over $90\%$ at $1000{\mu}g/mL$. Reducing power had similar tendency to electron donating ability while reducing power was significantly lower in samples compared to BHT. Two samples (Prunella vulgaris Linne val. lilacina Nakai and Inula japonica Thunberg) were found to have more than $50\%$ nitrite scavenging effect at $500{\mu}g/mL$ while 8 kinds samples (Zizyphus jujuba Miller, Cornus officinalis Siebold 81 Zuccarini, Chrysanthemum indicum Linne, Prunella vulgaris Linne var. lilacina Nakai, Inula japonica Thunberg, Acanthopanax sessiliflorum Seeman, Salvia miltiorrhiza Bunge and Curcuma longa Linne) showed more than $50\%$ nitrite scavenging effect at $1000{\mu}g/mL$. Prunella vulgaris Linne var. lilacina Nakai showed significantly stronger nitrite scavenging effect than other samples, and its activity was $59.62{\pm}1.573\%$ and $80.58{\pm}0.300\%$ at concentrations of 250 and $1000{\mu}g/mL$, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.11
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• pp.729-734
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• 2012

During chlorination processes dissolved organic nitrogen (DON) can form toxic nitrogenous disinfection byproducts and organic chloramines which have little or no bactericidal activity. DON needs to be removed before chlorination processes to reduce the formation of those products. This study investigated the removal of DON from surface water and reclaimed water by coagulation with aluminum sulfate (alum) and a cationic polymer (polyDADMAC). Removal characteristics of dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm ($UVA_{254}$) were compared with that of DON. Coagulation with alum removed DON, DOC, and $UVA_{254}$ with similar trends, but the removal of $UVA_{254}$ was highest. A dual coagulation strategy of alum and cationic polymer improved the removal of DON. Coagulation with cationic polymer alone was not effective due to its narrow range of charge neutralization. DON in reclaimed water was easier to remove than that in surface water, and higher molecular weight fraction (>10,000 Da) of DON was preferentially removed.

• Membrane Journal
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• v.18 no.4
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• pp.325-335
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• 2008

In this study, we used multi-channels ceramic membrane having larger permeate volume per unit time rather than tubular membrane. The hybrid process for advanced drinking water treatment was composed of granular activated carbons (GAC) packing between module inside and outside of multi-channels microfiltration membrane. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, modified solution was prepared with humic acid and kaolin. Kaolin concentration was fixed at 30mg/L and humic acid was changed as $2{\sim}10\;mg/L$ to inspect effect of organic matters. As a result, both resistance of membrane fouling ($R_f$) and permeate flux (J) were highly influenced by concentration of humic acid. Also, in result of water-back-flushing period (FT) effect, the shorter FT was the more effective to reduce membrane fouling and to enhance permeate flux because of frequent water-back-flushing. However, the optimal FT condition was 8 min when operating costs were considered. Then, the hybrid process using multi-channels ceramic membrane and GAC was applied to lake water treatment. As a result, average treatment efficiencies in our experiment using the hybrid process were 98.02% for turbidity, 75.64% for $UV_{254}$ absorbance, 7.18% for TDS and 84.73% for $COD_{Mn}$.

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.589-596
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• 2009

The spectroscopic characteristics and chemical oxygen demand (COD) oxidation efficiencies were investigated for dissolved organic matters (DOM) from diverse sources, which may indirectly affect the concentrations and the quality of DOM found in watersheds. The DOM investigated for this study showed a wide range of the percent distributions of refractory organic matter (R-OM) from 8 to 100%. Relatively high R-OM distributions were observed for the DOM with the source of head water, sediments, paddy soils, field soils, and treated sewage whereas the DOM from livestock waste, reed, weeds, algae, and attached algae exhibited lower R-OM percent distributions. The percent distribution of R-OM had positive correlations with specific UV absorbance (SUVA) and humidification indices (HIX) of DOM. The investigated DOM was classified into four different source groups (i.e., biota, vegetables, soils, sediments) by comparing the synchronous fluorescence spectra. The DOM group from biota source was characterized by a prominent presence of protein-like fluorescence (PLF) whereas fulvic-like fluorescence (FLF) was additionally observed for vegetable-source DOM. FLF became significant for the DOM from both soils and sediments although no PLF was found for soil-derived DOM. A range of COD oxidation efficiency was observed for the various DOM, ranging from 36 to 94% and from 65 to 125% for $COD_{Mn}$ and $COD_{Cr}$, respectively. The results indicate that $COD_{Cr}$ reflects the higher OM concentration than $COD_{Mn}$. However, 95% confidence intervals of the COD oxidation efficiencies were similar for the two types of COD, suggesting that $COD_{Cr}$ may not be the superior OM index to $COD_{Mn}$ in terms of the variability of the oxidation efficiency. No significant correlations were obtained between COD oxidation efficiencies and the spectroscopic characteristics of DOM for this study.

• Membrane Journal
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• v.21 no.1
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• pp.72-83
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• 2011

For advanced drinking water treatment of high turbidity water, we used the hybrid module that was composed of photocatalyst packing between outside of tubular ceramic microfiltration membrane and membrane module inside. Photocatalyst was PP (polypropylene) bead coated $TiO_2$ powder by CVD (chemical vapor deposition) process. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, modified solution was prepared with humic acid and kaolin. Water-back-flushing of 10 sec was performed per every period of 10 min to minimize membrane fouling. Resistance of membrane fouling ($R_f$) decreased and J increased as concentration of humic acid changed from 10 mg/L to 2 mg/L, and finally the highest total permeate volume ($V_T$) could be obtained at 2 mg/L. Then, treatment efficiencies of turbidity and $UV_{254}$ absorbance were above 98.5% and 85.7%, respectively. As results of treatment portions by membrane filtration, photocatalyst adsorption, and photo-oxidation in MF, MF + $TiO_2$, and MF + $TiO_2$ + UV processes, turbidity was treated little by photocatalyst adsorption, and photo-oxidation. However, treatment portions of humic acid by adsorption and photo-oxidation were above 10.7 and 8.6%, respectively.

• Journal of Mushroom
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• v.16 no.4
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• pp.324-330
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• 2018

The objective of this study was to evaluate antioxidant effect and tyrosinase inhibitory activity of white beech mushroom (Hypsizygus marmoreus) extracts. The white beech mushroom was extracted into hot water and methanol. Total polyphenol content was highest in the hot water extract ($8.4{\pm}3.27mg\;GAE/g$) compared to the methanol extract ($7.3{\pm}2.85mg\;GAE/g$). The flavonoids contents in hot water and methanol extracts were $3.8{\pm}3.81ug/mg$ and $2.5{\pm}1.95ug/mg$, respectively. The tyrosinase inhibitory activity of extract was increased in a dose dependent manner and tyrosinase inhibitory activity of extract (hot water extract, 69.72%; methanol extract, 52.67% at 40 mg/ml) was lower than those of positive control 2% arbutin (96%). The DPPH radical scavenging activity of the hot water and methanol extract was 80% and 74%, respectively. Hot water extract ($63.34{\pm}1.00uM\;TE/g$) were more effective in ORAC (oxygen radical absorbance capacity) value than methanol extract ($46.33{\pm}0.48uM\;TE/g$). The toxicity of hot water and methanol extracts was investigated using WST-1 (4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulphonate) assay on the B16BL6 melanoma cells.