• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.571-576
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• 2004

Since anaerobic/anoxic/oxic process, which is a typical mainstream biological nitrogen and phosphorus removal process, utilizes influent organic matter as an external carbon source for phosphorus release in anaerobic or anoxic stage, influent COD/T-P ratio gives a strong influence on performance of phosphorus removal process. In this study, a bench scale experiment was carried out for SBR process to investigate nitrogen and phosphorus removal at various influent COD/T-P ratio and nitrate loadings of 23~73 and 1.6~14.3g $NO_3{^-}-N/kg$ MLSS, respectively. The phosphorus release and excess uptake in anoxic condition were very active at influent COD/T-P ratios of 44 and 73. However, its release and uptake was not obviously observed at COD/T-P ratio of 23. Consequently, phosphorus removal efficiency was decreased. In addition, the phosphorus release and uptake rate in anoxic condition increased as the nitrate loading decreased. Specific denitrification rate had significantly high correlation with organic materials and nitrate loadings of the anoxic phase too. The rate of phosphorus release and uptake in the anoxic condition were $0.08{\sim}0.94kg\;S-P/kg\;MLSS{\cdot}d$ and $0.012{\sim}0.1kg\;S-P/kg\;MLSS{\cdot}d$, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1001-1009
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• 2000

This study is to find the utilization of intermittent aeration system, around S-COD, T-COD, SS, timewise changes of treatment performance, sludge conversion yield, changes of temperature and pH, etc. In consequence of this study, factors of temperature correction showed 1.052 on continuous aeration, and 1.056 on intermittent aeration which is more sensitive to temperature through a minute degree. Meanwhile, sludge conversion yield on intermittent aeration showed lower and more economical than that on continuous aeration. In case of changing pH, treatment water of both reactors worsened slightly in acid but improved in alkali. In general. considering the quality of effluent water, variation pH of effluent water, etc. the case of intermittent aeration was more favorable than that of continuous aeration.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.4
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• pp.41-50
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• 2017

The design of proper agitation system is requisite in biological waste treatment and energy generation plant, which is affected by viscosity, impeller types, and power consumption. In the present work, hydrogen fermentation of food waste was conducted at various operational pHs (4.5~6.5) and substrate concentrations (10~50 g Carbo. COD/L), and the viscosity of fermented broth was analyzed. The $H_2$ yield significantly varied from 0.51 to $1.77mol\;H_2/mol\;hexose_{added}$ depending on the pH value, where the highest performance was achieved at pH 5.5. The viscosity gradually dropped with shear rate increase, indicating a shear thinning property. With the disintegration of carbohydrate, the viscosity dropped after fermentation, but it did not change depending on the operational pH. At the same pH level, the $H_2$ yield was not affected much, ranging $1.40{\sim}1.86mol\;H_2/mol\;hexose_{added}$ at 10~50 g Carbo. COD/L. The zero viscosity and infinite viscosity of fermented broth increased with substrate concentrations, from 10.4 to $346.2mPa{\cdot}s$, and from 1.7 to $5.3mPa{\cdot}s$, respectively. There was little difference in the viscosity value of fermented broth at 10 and 20 g Carbo. COD/L. As a result of designing the agitation intensity based on the experimental results, it is expected that the agitation intensity can be reduced during hydrogen fermentation. The initial and final agitation intensity of 30 g Carbo. COD/L in hydrogen fermentation were 26.0 and 10.0 rpm, respectively. As fermentation went on, the viscosity gradually decreased, indicating that the power consumption for agitation of food waste can be reduced.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.3
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• pp.10-17
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• 2005

In this paper, the life cycle assessment(LCA) methodology is applied to Personal Computer's basic materials in order to analyze the impact to the environment. LCA data collection is carried out taking into account on main materials of PC's parts and component. And the impact assessment is the environmental burden on three factor into air emission(CO2, SOx, NOx), five factor into water emission(BOD, COD, SS, N, P), and three factor on transported substance(cl, NH4, SO4). According to the result, the environmental burden of PC's basic materials was proved to be used total energy 6,285Mj and emitted CO2 259.8kg, SOx 3,571g, NOx 330g, COD 1,328g, P 246g, N 2,434g. And this paper was presented the problems of its disposition-incinerating, landfill, and recycling.

• Korean Journal of Ichthyology
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• v.19 no.4
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• pp.318-323
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• 2007

The feeding habits of Pacific cod (Gadus macrocephalus) were studied based on the examination of stomach contents of 192 specimens collected from November, 2005 to January, 2006 in the coastal waters off Gadeok-do, Korea. The size of Pacific cod ranged from 35 to 82 cm in standard length (SL). Pacific cod mainly consumed shrimps such as Eualus spathulirostris, Crogon hakodatei and C. affinis and fishes. Its diet also included small quantities of cephalopods, amphipods, hermit crabs and crabs. Individuals between 35 cm and 45 cm SL mainly consumed shrimps. The portion of shrimps decreased with increasing fish size, and this decrease was paralleled with increased consumption of fishes and cephalopods. In this study we found Syngnathus schlegeli in the stomach contents of many Pacific cod specimens. S. schlegeli is a typical seagrass fish species which inhabits in seagrass beds, This fact means that Pacific cods stay in the seagrass beds during spawning period. Therefore migration of Pacific cod to coastal waters off Gadeok-do during spawning period seems to be a survival strategy for its larvae and small juveniles to stay in seagrass beds which provide with abundant foods and shelters to many commercial fish species.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.587-595
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• 2000

The most problems of domestic sewage for BNR(Biological Nutrients Removal) process are deficiency of carbon source and low C/N ratio. Primary sludge fermentation is seemed to be one of the best solutions producing biodegradable organic substrates. Soluble organic materials from sludge fermentation are mainly SCFAs(Short-Chain Fatty Acids) with 2~5 carbon atoms. In this research, it was attempted to apply $A_2/O$ process with the side-stream acid fermenter to improve the nutrients removal efficiency. The result showed that proper SCFAs production is about 3.000mg/L with SRT of 4~5 days. SCFAs yield of approximately 0.10~0.16 mg SCFAs(as COD) per mg of primary sludge(as COD) were achieved. The ratio of acetic. propionic. butyric and valerie acid were 1, 0.7, 0.5 and 0.6. Significant improvements of nutrients removal over 70% in BNR process were observed. thus will reduce the demand for chemical dosing to increase nutrients removal efficiency. When the fermentate was entered $A_2/O$ process, the ratio of phosphate release to substrate uptake amounts to $0.34gPO_4-Pg^{-1}COD$.

• Journal of Korean Biological Nursing Science
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• v.3 no.1
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• pp.41-52
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• 2001

This study was undertaken to investigate the effects of n-6(corn oil) & n-3(fish oil) fatty acids on infarction size and the cerebral activities of antioxidant enzyme in rat focal brain ischemia model. Weaning Sprague-Dawley rats were fed with either corn oil supplemented diet(COD, 14% corn oil) or fish oil supplemented diet(FOD, 14% menhaden oil) for 6 weeks. The right middle cerebral artery was occluded for 2 hours with a silicon rubber coated nylon surgical thread. After 24 hours of recirculation, the rats were sacrificed and brain sections were photographed using CCD camera after staining with 2, 3, 5-triphenyltetrazolium chloride for 60 minutes in room temperature. The infarcted area was measured and the volume of infarction was calculated. Catalase(CAT), superoxide dismutase(SOD) activities, and fatty acid composition in the brain were also measured. The total and corrected infarction volumes were not significantly different between FOD and COD group. The docosagexaenoic acid(DHA) and DHA content/arachidonic acid(AA) ratio of the cerebral cortex, an index of defense against lipid oxidation, were significantly increased in FOD group compared to those of COD group(p<0.05). In the left cortex(non-infarction side) as well as the right cortex(infarction side) of FOD group, CAT and Cu/Zn SOD activities were higher than those of the COD group(p<0.05). However, CAT and Cu/Zn SOD activities were not significantly different between the left cortex(non-infarction side) and the right cortex(infarction side) of both FOD and COD group. GPx activities were also not significantly different between two groups. Our results demonstrate that the brain infarction size in FOD and COD were not significantly different. However, cerebral lipid composition and antioxidant enzyme activities in FOD and COD group were different. Fish oil, a source of n-3 polyunsaturated fatty acid(PUFA) and corn oil, that of n-6(PUFA) may have a protective effect against oxidative stress induced via different mechanisms.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.169-185
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• 2017

Physicochemical properties of water quality were analyzed to understand the long-term variations in Lake Youngrang from 1998 to 2015. Nonparametric statistical methods were applied to deduct correlation among water quality parameters and water quality trend. In total observations(N=64), the Secchi depth (SD) transparency showed significant positive correlation with salinity (r=0.458) and highly significant negative correlation with chlorophyll-a (r= -0.649) for p<0.0001 in two-tailed test of Spearman's rank correlation. Significant negative correlations of SD were observed with chemical oxygen demand (COD), total phosphorus (TP) and total nitrogen (TN). These correlation patterns were very similar in rainy (N=25) and non-rainy (N=39) periods too. Chlorophyll-a (Chl-a) had significant correlation with COD. Sen's slope test was performed along with Mann-Kendall trend test (significance ${\alpha}=0.05$, two-tailed) to find water quality trend. Positive trends were observed for SD and salinity with Sen's slopes 0.012 and 0.385, respectively (p<0.0001). Negative significant trends were observed for total nitrogen (TN) and Chl-a with Sen's slopes -0.02 (p<0.0001) and -0.346 (p=0.0010), respectively. Temperature, COD and phosphorus components had no trends. Carlson's trophic state index (TSI) for SD, TP and Chl-a were obtained in the ranges of 46~80, 37~82 and 39~82, respectively. Trophic index values suggest that Lake Youngrang was mesoeutrophic to eutrophic and there could be possibility of anoxia during the summer and dominance of blue-green algae. Excess nutrient inputs from external and internal sources were the causes of eutrophication in this lake. The findings of this study would be helpful to recognize water quality variables to manage the water body.

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.72-81
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• 2007

The purpose of this study was to develop a multi-metric Lentic Ecosystem Health Assessment (LEHA) model and apply model to dataset sampled from Daechung Reservoir in September 2005. The metrics were composed of 11 parameters such as physical, chemical and biological variables. The metric attributes of $M_1{\sim}M_8$ followed after the model of biological integrity using fish assemblages that previously adapted in lotic ecosystems, while the metrics of $M_9{\sim}M_{11}$ were added on the basis of literature. The metric of $M_9$ reflected habitat conditions in the littoral zone and the metric of $M_{10}$ reflected chemical conditions of the reservoir. For the application of regression analysis of long-transformed conductivity [$Log_{10}$(Cond)] against $COD_{Mn}$, based on 150 sampling sites at Korean reservoirs, showed that the variation of conductivity was explained 77.4% [$COD_{Mn}=4.42{\times}Log_{10}(Cond)-5.43;\;R^2=0.774$, p<0.01, n=150] by the variation of $COD_{Mn}$. The metric of $M_{11}$ was based on Tropic State Index (TSI), based on chlorophyll-${\alpha}$ concentrations (Chl-${\alpha}$). Analysis of TSI $(Chl-{\alpha})$ showed that above 50 was estimated "1", $40{\sim}50$ was estimated "3" and below 40% was estimated '5'. Overall, velues of LEHA in the reservoir averaged 30.5, indicating a "fair${\sim}$poor condition", which is judged by the criteria of U.S. EPA (1993). More studies such as metric numbers and attributes should be done for the application of the model.

• Korean Journal of Environmental Agriculture
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• v.31 no.3
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• pp.235-247
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• 2012

BACKGROUND: Gohyeon Stream is the municipal eco-stream of 7.1km in total length which flows through the downtown area of Gohyeon in Geoje city, rising from the watershed of Mundong Water Fall. Gohyeon district in Geoje city has been a rapid growing area centering in Geoje city and then experienced an rapid increase in population. Large amounts of sewage pollutants have been spewed into Gohyeon Stream from its tributaries, due to the lack of sewer system. Gohyeon Stream is laced with unhealthy levels of fecal coliform (FC). Restoration of water quality in Gohyeon Stream is no less inevitable in behalf of its ecosystem and the citizen. In this study, the water quality of Gohyeon Stream and its tributaries was examined temporally and spatially, and their relationships were comparatively analyzed to give useful basic data applying to a restoration project of the water quality of Gohyeon Stream. METHODS AND RESULTS: The samples ware taken at 20 points in Gohyeon Stream and 19 points in its tributaries during the rainy and dry seasons, respectively, and examined on the parameters of pH, temperature, salinity, dissolved oxygen (DO), suspended solid (SS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), dissolved inorganic nitrogen (DIN; $NH_3$-N, $NO_3$-N, $NO_2$-N), disolved inorganic phosphorus (DIP; $PO_4$-P) and FC. The data were analyzed using a comparative analysis and Pearson's correlation analysis among the parameters. During the rainy season, the concentration of SS was high in the upper region of Gohyeon Stream, and the concentrations of COD, DIN and DIP were low in the upper region and high in the middle and lower regions. During the dry season, the concentration of SS was low and the concentrations of COD, DIN, DIP and FC were high in all regions. The Pearson's correlation analyses showed that the relationships between DO and FC, COD and DIP, and DIN and FC during the rainy season as well as between DO and DIN, SS and FC, COD and DIP, and DIN and DIP during the dry season were significant. CONCLUSION: During the rainy season, the upper region of Gohyeon Stream flowed the high level of SS, the middle region the high level of nutrients due to an agricultural run-off, and the lower region the high level of nutrients due to a sewage inflow. During the dry season, the water quality of Gohyeon Stream was directly and sensitively influenced on the inflow of sewage from the tributaries.