• Journal of Korean Society of Environmental Engineers
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• v.39 no.11
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• pp.613-625
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• 2017

For two agricultural reservoirs that are rented for fishing spots, benthic nutrient fluxes experiment were performed two times with two sediments from fishing-effective zone and one sediment from fishing-ineffective zone using laboratory core incubation in oxic and anoxic conditions. During benthic nutrient fluxes experiment, the changes in DO, EC, pH, and ORP in the supernatant were not significantly different between fishing-effective zone and fishing-ineffective zone, and were similar to the sediment-hypolimnetic diffused boundary layer in agricultural reservoir. Except for $NO_3{^-}-N$, more benthic nutrient fluxes of $NH_4{^+}-N$, T-P, and $PO{_4}^{3-}-P$ from sediment to hypolimnetic was measured in anoxic than in oxic conditions (p<0.05). As the DO concentration in hypolimnetic decreases, the microorganism-mediated ammonification is promoted, the nitrification is suppressed, and finally the $NH_4{^+}-N$ diffuses out from sediment to hypolimnetic. Also, the diffusion of T-P and $PO{_4}^{3-}-P$ from sediments to hypolimnetic is accelerated through the dissociation of the phosphorus bound to both organic matters and metal hydroxides. The difference in the benthic nutrient diffusive fluxes between fishing-effective zone and fishing-ineffective zone was not statistically significant (p>0.05). Therefore, it was found that fishing activities did not increase the benthic nutrient diffusive fluxes to a statistically significant level. Due to the short fishing activities of 10 years and the rate-limited diffusion of the laboratory core incubation, the contribution of fishing activities on sediment pollution is estimated to be low. No significant correlation was found between the total amount of nutrients in sediment and the benthic nutrient diffusive fluxes in both aerobic and anaerobic conditions. Therefore, nutrients input from various nonpoint sources of watersheds are considered to be a more dominant factor rather than fishing activities in water quality deterioration, and both aeration and water circulation in hypolimnetic were required to suppress the anoxic environment in agricultural reservoirs.

• Journal of Wetlands Research
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• v.23 no.4
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• pp.327-341
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• 2021

The riparian eco-belt is an efficient technique that can reduce non-point pollution sources in the basin and improve ecological connectivity and health. In Korea, a legal system for the construction and management of riparian eco-belts is in operation. However, it is currently excluded that rivers and floodplains in dam reservoir that are advantageous for buffer functions such as control of non-point pollutants and ecological habitats. Accordingly, this study presented and analyzed a plan to select a site for an integrated riparian ecol-belt that comprehensively evaluates the water quality and ecosystem characteristics of each dam floodplain and riparian zone for the Daecheong Dam basin in Geum River watershed. First, the Daecheong Dam basin was divided into 138 sub-basin with GIS, and the riparian zone adjacent to the dam floodplain was analyzed. Sixteen evaluation factors related to the ecosystem and water quality impact that affect the selection of integrated riparian eco-belt were decided, and weights for the importance of each factor were set through AHP analysis. The priority of site suitability was derived by conducting an integrated evaluation by applying weights to sub-basin by floodplains and riparian zone factors. In order to determine whether the sites derived through GIS site analysis are sutiable for actual implementation, five sites were inspected according to three factors: land use, pollution sources, and ecological connectivity. As a result, it was confirmed that all sites were appropriate to apply integrated riparian ecol-belt. It is judged that the riparian eco-belt site analysis technique proposed through this study can be applied as a useful tool when establishing an integrated riparian zone management policy in the future. However, it might be necessary to experiment various evaluation factors and weights for each item according to the characteristics and issues of each dam. Additional research need to be conducted on elaborated conservation and restoration strategies considering the Green-Blue Network aspect, evaluation of ecosystem services, and interconnection between related laws and policy and its improvements.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.10
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• pp.1438-1446
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• 2016

The objectives of this study were to investigate the effects of superheated steam (SHS) treatment on the physicochemical and microbial properties of garlic. The garlic was treated by SHS at temperatures of 100, 150, 200, 250, 300, and $350^{\circ}C$ for 60 s. The moisture content of raw garlic was lower than that of SHS-treated garlic. The total thiosulfinate and pyruvate contents were dramatically reduced by SHS treatments. The antioxidant activities of garlic measured by ferric reducing/antioxidant power, 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical scavenging assay, and total phenolics content decreased by SHS. The major volatile sulfur compounds of garlic such as diallyl disulfide, allicin, allyl sulfide, diallyl sulfide, and diallyl trisulfide were significantly reduced by SHS. The antimicrobial effects of raw garlic were stronger than those of SHS-treated garlic against three strains of bacteria, including Staphylococcus aureus, Escherichia coli, and Bacillus cereus. However, total aerobic bacteria in garlic were dramatically reduced by SHS from 8.6 to 2.9 log CFU/g. The results from the sensory evaluation show that SHS treatment of garlic above $200^{\circ}C$ provides better acceptably due to reduction of off-flavor and pungency of garlic. These results suggest that superheated steam treatment can used as an efficient process for reducing garlic off-flavor and pungency.

• Journal of Food Hygiene and Safety
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• v.36 no.5
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• pp.447-453
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• 2021

In this study, the effectiveness of physical control technology, a combined light sterilization (LED, UV) and hot water treatment in reducing Aspergillus ochraceus for food production environment was investigated. In brief, 1 mL aliquot of A. ochraceus spore suspension (10^7-8 spore/mL) was inoculated onto stainless steel chips, which was then dried at 37℃, and each was subjected to different physical treatment. Treatments were performed for 0.5, 1, 2, 5, 8, and 11 hours to reduce the strains using a light-emitting diode, but no significant difference was confirmed among the treatments. However, a significant reduction was observed on the chips treated with UV-C exposure and hot water immersion. After being treated solely with 360 kJ/m² of UV-C on stainless steel chip, the fungi were significantly reduced to 1.27 log CFU/cm². Concerning the hot water treatment, the initial inoculum amount of 6.49 log CFU/cm² was entirely killed by immersion in 83℃ water for 5 minutes. Maintaining a high temperature for 5 minutes at the site is difficult. Thus, considering economic feasibility and usability, we attempted to confirm the appropriate A. ochraceus reduction conditions by combining a relatively low temperature of 60℃ and UV rays. With the combined treatments, even in lukewarm water, A. ochraceus decreased significantly through the increases in the immersion time and the amount of UV-C irradiation, and the yield was below the detection limit. Based on these results, if work tools are immersed in 60℃ lukewarm water for 3 minutes and then placed in a UV sterilization device for more than 10 minutes, the possibility of A. ochraceus cross-contamination during work is expected to be reduced.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.3
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• pp.63-76
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• 2015

This study was carried out to suggest improvement plans for problems with the landscape areas of highway service areas. The survey factors were land use, placement of green area and land coverage in terms of spatial and environmental property. Noise and topographic structure in detached green areas were surveyed in terms of impact factor. The status of the planting area around each service area was analysed in regards to planting structure and planting landscape. As a result, the mean of rations of land use were 81.6% building and 18.4% green areas, which were composed of 5.4% landscape area, 9.1% buffer area, etc. Planting areas as usable space accounted for only 0.7%, and the result of noise measurement was different according to the distribution of highway and service area and type of detached green area. The mean of ratio of planting area was 18.4%, which consists of 6.7% landscape planting, 3.4% other green area, 4.6% buffer area, 2.0% buffer and landscape area, 1.1% shade planting and 0.5% landscape and shade planting. Most planting areas aim at landscape appreciation and areas in which visitors can relax and gain recreation were insufficient. The planting structures of service areas were 52.2% canopy layer, 11.8% shrubs and 9.4% canopy and shrub layers, and most of the planting areas were a single layer of green area. Multi-layered planting structures in the landscape and buffer areas were required and a shade planting area was needed to improve amenities as planting canopy layered trees. This study suggested improvement methods for based environments, spatial function and planting function in landscape areas.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.181-190
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• 2003

An investigation was conducted on the aquatic environment of the Okchon Stream watershed six times from May to September 2002. The results of investigation revealed that variation of environmental factors were quite significant for each stream and reach, showing a significant difference between running water and stagnant water. Aquatic nutrients were relatively low in the upstream, gradually increasing as the influx of treated wastewater into the stream increased. This suggests that the point source definitely affected the nutrient content of the stream. In particular, the variations of SRP and $NH_4$ were very distinct in the watershed compared to other nutrients. Thus, it can be considered as a major factor in evaluating the effect of treated wastewater. Immediately after the influx of treated waste-water, the average content of SRP rose to 919.3 ${\mu}g$ P/l. This was a very effective level in the watershed, suggesting that the percentage of the nutrients in the water was controlled by the content of P. The constant supply of treated wastewater was found to be a critical factor in triggering the increase in chl-a in the embayment of the stream. With the proliferation of the blue-green algae, the content of chl- a ranged 234.5${\sim}$1,692.2 ${\mu}g/l$. The maximum standing crops exceeded $1.0{\times}10^6$ cells/ml in August, which was more than 200 times the level for red tide in the freshwater. This result was well reflected in other environmental factors, with 100% of AFDM/TSS reflecting the severity of water pollution by algae. Therefore, the reduction of P and N con-tents in the treated wastewater is critical in improving the aquatic environment of the stream as well as water quality management for the reservoir.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.389-397
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• 2015

Dongchun, one of the representative streams in urban area, is a downstream that is connected to Hogyechun, Bujeonchun, Jeonpochun, Danggamchun, and Gayachun as its upstream. Hogyechun has been mostly covered with concrete structures for decades, causing sewage pollution from the upstream, overflow of the downstream region and other serious pollution that gave rise to many civil complaints from the residents nearby. In this study, we analyzed 3 stations, including control station for water quality and malodor changes of Hogyechun after applying the microbial augmentation (BM-2) for a few months including the rainy season. Amounts (g/h) of DO in the middle site (Middle) and the downstream site (Borim) increased by 1.7 times compared with the upstream site (Chuhae) after augmentation for about 2 months. Amounts (g/h) of COD and $NO_3{^-}N$ decreased by 2 and 1.7 times, respectively, in the middle and downstream sites while SS increased by 7.5 and 22 times in the middle and downstream sites, respectively. Moreover, odor removal efficiencies at the middle and downstream sites were 65% and 19%, respectively, indicating the microbial activity in reduction of malodor in the polluted stream. The dominant microbial species of the sampling sites were Hydrogenophaga caeni, Sphaerotilus natans, Acidovorax radicis, Acidovorax delafieldii, and Cloacibacterium rupense. Densities of the two species Sphaerotilus natans and Acidovorax delafieldii were significantly increased in the middle site after augmentation which possessed potential odor removal and denitrification activity, respectively. Potential pathogens (e.g., Arcobacter cryaerophilus) were also removed from the middle site after the implementation.

• Korean Journal of Ecology and Environment
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• v.40 no.3
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• pp.481-488
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• 2007

This study covers the relationship between land use and water quality items. The kinds of land used in this study were almost agricultural areas with paddy fields and mountains. We set up zones at intervals of 200 m along 48 watersheds all over the country. The analysis showed high relationship between the water quality and the land use specially on the areas in the 400 m radius from the stream so that the areas needed to have strict managements. In the cases of residential area and upland, the positive correlation had a tendency to be lower when they were farther away from the stream. It depended on the increase of rainfall during July and August which affected on the water quality of reservoirs. The correlation analysis of paddy fields resulted in negative relationship, which indicated that paddy fields did not have negative effect on the quality of the stream. Through adequate irrigation and Management, paddy fields may be led to have positive effect on the quality of the reservoirs. In the case of forest, it also resulted in negative correlation so it was concerned as a positive factor which helped to improve water quality. Furthermore more than 00% of the land used in this study is comprised of forest so that it would have a positive effect on the reservoir management.

• Research in Plant Disease
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• v.29 no.4
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• pp.384-389
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• 2023

Milling can affect the distribution of mycotoxins in small grains. To investigate the effects on barley, seven hulled barley and three naked barley samples naturally contaminated with trichothecenes and zearalenone were obtained and milled at commonly used rates. Both barleys were simultaneously contaminated with deoxynivalenol and its acetyl derivatives (98.1-2,197.8 ㎍/kg), nivalenol and its acetyl derivative (468.5-3,965.1 ㎍/kg), and zearalenone (4.1-274.2 ㎍/kg). Milling hulled barleys at a rate of 67% reduced the mycotoxins in the grain by 90.9% for deoxynivalenol, 87.7% for nivalenol, and 93.2% for zearalenone. The reduction in naked barleys (milled at a rate of 70%) was slightly lower than in hulled barleys, with 88.6% for deoxynivalenol, 80.2% for nivalenol, and 70.1% for zearalenone. In both barleys, the acetyl derivatives of deoxynivalenol and nivalenol were reduced by 100%. However, barley bran had significantly higher mycotoxin concentrations than the pre-milled grains: bran from hulled barley had a 357% increase in deoxynivalenol, 252% increase in nivalenol, and 169% increase in zearalenone. Similarly, bran from naked barley had a 337% increase in deoxynivalenol, 239% increase in nivalenol, and 554% increase in zearalenone. These results show that mycotoxins present in the outer layers of barley grain can be effectively removed through the milling process. As milling redistributes mycotoxins from the grain into the bran, however, it shows that advance monitoring of barley bran is recommended when using barley bran for human or animal consumption.

• Korean Journal of Environmental Agriculture
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• v.32 no.1
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• pp.1-8
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• 2013

BACKGROUND: Many studies associated with cadmium (Cd) immobilization using lime fertilizer have been conducted for several decades. However, these studies did not suggest exact mechanism of Cd immobilization using lime fertilizer and evaluated effect of lime fertilizer on Cd phytoavailability in rice paddy soil under field condition. METHODS AND RESULTS: This study was conducted to determine exact mechanism of Cd immobilization using lime fertilizer and evaluate liming effect on Cd uptake of rice in contaminated paddy soil. $Ca(OH)_2$ was mixed with Cd contaminated arable soil at rates corresponding to 0, 1,000, 2,000, 4,000, and 8,000 mg/kg. The limed soil was moistened to paddy soil condition, and incubated at $25^{\circ}C$ for 4 weeks. $NH_4OAc$ extractable Cd concentration in soil decreased significantly with increasing $Ca(OH)_2$ rate, since $Ca(OH)_2$ markedly increased net negative charge of soil by pH increase, and decreased bioavailable Cd fractions (F1; exchangeable + acidic and reducible Cd fraction). Calculated solubility diagram indicated that Cd solubility was controlled by soil-Cd. $NH_4OAc$ extractable Cd and F1 concentration were negatively related to soil pH and negative charge. $Ca(OH)_2$ was applied at rates 0, 2, 4, and 8 Mg/ha and then cultivated rice in the paddy soil under field condition. Cadmium concentrations in grain, straw, and root of rice plant decreased significantly with increasing application rate of $Ca(OH)_2$. CONCLUSION(S): Alleviation of Cd phytoavailability with $Ca(OH)_2$ can be attributed primarily to Cd immobilization due to the increase in soil pH and negative charge rather than precipitation of $Cd(OH)_2$ or $CdCO_3$, and therefore, $Ca(OH)_2$ is effective for reducing Cd phytoavailability of rice in paddy soil.