• The Journal of the Korea Contents Association
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• v.9 no.8
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• pp.1-8
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• 2009

With the development of IT convergence technology and the construction of master plan for the four rivers restoration of the government, the importance of the eco-friendly water pollution management is being spotlighted. In this paper, we proposed the effective water pollution management using the reservoir tank automatic classification for improving the water quality and on-line managing efforts of ceo-friendly reservoir tanks. The proposed method defined the seven factors of water pollution evaluation and managed the water pollution according to hydrogen ion concentration(pH), chemical oxygen demand(COD), suspend solid(SS), dissolved oxygen(DO), count of coliform group(MPN), total phosphorus(T-P), and total nitrogen(T-N) using the sensors. We measured the values for the seven factors from the reservoir tank and normalized to ranging from 1 to 9. To evaluate the performance of the water pollution management using the reservoir tank automatic classification, we conducted F-measure so as to verify usefulness. This evaluation found that the difference of satisfaction by the traditional system was statistically meaningful.

• Fisheries and Aquatic Sciences
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• v.19 no.4
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• pp.17.1-17.9
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• 2016

The seasonal variation of fecal coliforms (FCs) and physicochemical factors was determined in seawaters of the Hansan-Geojeman area, including a designated area for oyster, and in inland pollution sources of its drainage basin. The mean daily loads of FCs in inland pollution sources ranged from $1.2{\times}10^9$ to $3.1{\times}10^{11}$ most probable number (MPN)/day; however, the pollutants could not be reached at the designated area. FC concentrations of seawaters were closely related to season, rainfall, and inland contaminants, however, within the regulation limit of various countries for shellfish. The highest concentrations for chemical oxygen demand (COD) and $chlorophyll-{\alpha}$ in seawaters were shown in the surface layer during August with high rainfall, whereas the lowest for dissolved oxygen (DO) in the bottom layer of the same month. Therefore, it indicates that the concentrations of FC, COD, DO, and $chlorophyll-{\alpha}$ of seawaters were closely related to season and rainfall.

• Environmental Engineering Research
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• v.25 no.2
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• pp.251-257
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• 2020

This study was performed to verify the possibility of nitrification and denitrification in a single reactor. In batch type experiment, optimal point of experimental conditions could be found by performing the experiments. When supply location of microbubbles was located at half of width of the aeration tank and operating pressure of 0.5 bar, it was possible for zones in the aeration tank to be separated into anoxic and aerobic by controlling air suction rate according to operating pressure of the generator. To be specific, the concentration of dissolved oxygen (DO) in zone 1 and 2 of the aeration tank could be maintained as less than 0.5 mg/L. Also, in the case of concentration of oxygen in zone 3 and 4, the concentration of DO was increased up to 1.7 mg/L due to effects of microbubbles. In continuous flow type experiment based on the results of batch type experiments, the removal efficiency of nitrogen based on T-N was observed as 39.83% at operating pressure of 0.5 bar and 46.51% at operating pressure of 1 bar so it was able to know that sufficient air suction rate should be required for nitrification. Also, denitrification process could be achieved in a single reactor by using ejector type microbubble generator and organic matter and suspended solid could be removed. Therefore, it was possible to verify that zones could be separated into anoxic and aerobic and nitrification and denitrification process could be performed in a single reactor.

• Journal of the Korean Geographical Society
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• v.39 no.4
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• pp.544-561
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• 2004

Weekly monitoring of discharge and water quality in forested and agricultural subcatchments were performed to understand the difference of water quality caused by land uses in Doegwollyong area. Correlations between water quality variables including discharge were analyzed for the same purpose. There was little variation of water Quality in forested subcatchment. On the other hand, the range of water quality variation in agricultural subcatchment was wide due to soil loss and the application of chemical fertilizers and livestock manure. Dissolved oxygen(DO) had strong negative correlation with discharge in both subcatchments. Total nitrogen(T-N) and potassium ion(K$^{+}$) had stronger positive correlation with discharge in forested subacatchment than in agricultural one. On the other hand, total suspended sediments(TSS), total phosphorus(T-P), and chemical oxygen demand(COD) had stronger correlation with discharge in agricultural subcatchment than in forested one. As water pollution of the Doam Lake, especially the increase of T-P is serious, soil conservation is very important to improve water quality. In particular, the loss of soil and nutrients from late June till early July were more serious than any other seasons, therefore it is necessary to apply environmentally sustainable methods of cultivation.n.

• Journal of the Korean GEO-environmental Society
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• v.10 no.1
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• pp.43-48
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• 2009

This study was performed to investigate the characteristics of nutrient removal by Sequencing Batch Reactor (SBR) system, which could achieve high removal efficiencies of nitrogen and phosphorus and make it possible convenient management and operation. In this study, dissolved oxygen (DO), chemical oxygen demand (COD), nitrogen, and phosphorus in SBR system were examined by variation of anoxic-oxic phase repetition in order to optimize an operational method. The 1~4 times of anoxic-oxic phases (Run 1~4) were repeated during 1 cycle operation period. As the repetition frequency increased, it was more difficult to maintain DO condition enough for denitrification. The SBR system showed high COD removal efficiency more than 91% regardless of operational condition. About 68% of nitrogen removal rate was obtained in conditions of 2 or 3 times repetition of anoxic phases, in which NOx-N among discharged total nitrogen account for more than 99%. Approximately 40% of phosphorus was eliminated in the conditions of 1~3 times of anoxic phase repetition.

• Hwankyungkyoyuk
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• v.22 no.1
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• pp.12-30
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• 2009

The relationship between marine environmental improvement and environmental perception of the inhabitants was investigated. For this purpose, the seawater and bottom materials were analysed. Apart from this, the questionnaire surveys were also conducted around the Sun-so coastal area. In order to examine the improvement in the marine environment, 12 monitoring sites, which are located around Sun-so coast and can be divided into two parts such as inland (GW1-GW6) and outland (GW7-GW12) sea, were chosen. All the collected samples were analyzed to find out the quality of seawater (temperature, pH, salinity, dissolved oxygen: DO, chemical oxygen demand: COD and suspend solid: SS), nutrients (total nitrogen: TN and phosphate: $PO_4-P$) and bottom materials (COD, volatile solids: VS) as per the standard analytical procedures. In addition, the questionnaire mainly focused on the following three factors: 1) social economy, 2) dependent environmental awareness and 3) independent environmental awareness related with the environmental education. The monitoring studies indicated that the marine environment of the Sun-so coast showed various trends for analyzing parameter. No significant temporal changes in temperature, pH and salinity were observed. However, the other parameters showed decreasing (COD, SS, TN, $PO_4-P$ and VS) and increasing (DO) trends according to the quality of seawater and bottom materials. The questionnaire survey clearly showed that most of the residents in Sun-so recognized the improvement of marine environment as compared with the situation experienced in the past. The dredging project which is closely related with economic and living conditions of the local residents led to alter the environmental perceptions and attitudes. The survey also indicated that the inhabitants perceived the necessity of the environmental education (87% of respondents) and preferred regular schooling (55% of respondents) as effective and practical education methods.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.11 no.4
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• pp.243-247
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• 1978

COD and sulphide contents in the superficial mud in three oyster farms, one near Gajo-do in Chinhae Bay, the second near Eup-do in Koseong Bay and the third near Eogu in Keoje Bay, around the Chungmu area have been monthly determined for seven months from May through November in 1978. Bottom water was also checked for chlorophyll-a, dissolved oxygen, COD and sulphide. In general, large amounts of COD and sulphide in the superficial mud were found in the summer season, COD was 38.1 mg/g dry mud in the farm near Gajo-do, 32.3 mg/g near Eup-do and 25.1 mg/g in Eogu farm and sulphide was 0.313 mg/g dry mud, 0.517 mg/g and 0.132 mg/g respectively. COD and sulphide contents in the farms near Gajo-do and Eup-do were a little over the upper level of the eutrophic range, that is, 30 mg/g dry mud in COD and 0.3 mg/g dry mud in sulphide. It shows that the above two oyster farms were already eutrophicated. However, among three oyster farms no clear difference in bottom water was found.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.6
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• pp.394-410
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• 2007

Anchovy spawn from the end of May to mid-October, when the water temperature is $14.8-27.2\;^{\circ}C$ and the salinity is 26.0-33.6 psu. The main spawning season is between July to August, when the water temperature is $21.7-27.2\;^{\circ}C$ and the salinity is between 26.0-32.2 psu. The main spawning grounds of anchovy are coastal areas shallower than 50 m around the islands located in the Jeju Strait. Anchovy larvae are distributed near the fronts between Chuja-do, Jangsu-do, Yeoseo-do, and the open sea rather than in the spawning grounds. Anchovy eggs and larvae density increased in accordance with the high level of $Chlorophyll-{\alpha}$ during the summer season (July-August). In terms of the suspended sediment (SS) levels along the northern coast of the Jeju Strait, high densities of anchovy eggs (12.0-18.0 mg/L) were observed, mainly in the area affected by the coastal waters of the southern sea with high SS levels, while larvae (10.0-19.0 mg/L) tended to be distributed over a wide area with high SS levels, including the open sea. In terms of the dissolved oxygen (DO) content, eggs (5.4-6.8 mg/L) were observed in coastal areas with a high DO content, while larvae (4.2-6.4 mg/L) were distributed widely in areas with a relatively low DO content, from the southern coast to the open sea.

• Journal of Environmental Science International
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• v.8 no.1
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• pp.107-113
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• 1999

A new biological nutrient removal system combining $A^2/O$ process with fixed film was developed in this work and the characteristics of denitrification were especially investigated in the combined fixed film reactor(CFFR). Media was added in the anaerobic, anoxic and aerobic reactors, respectively. Tests were made to establish the effluent level of $NO_x-N$, COD, DO and nitrite effects on $NO_x-N$ removal in the CFFR by decreasing hydraulic retention time (HRT) from 10.0 to 3.5 hours and by increasing internal recycle ratio form 0% to 200%. The influent was synthesized to levels similar to the average influent of municipal wastewater treatment plants in Korea. SARAN media with a porosity of 96.3% was packed 40% / 130% / 25% based on its reactor volume, respectively. It was found that COD rarely limited dentrification in the anoxic reactor because of high $C/NO_x/-N$ ratio in the anoxic reactor, while DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent inhibited denitrification in the anoxic reactor. It was proved that the critical points of DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent were 0.15mg/L and 10%, respectively. As the internal recycle ratio increased, DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent increased. Especially, at the condition of internal recycle ratio, 200%, DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent exceeded the critical points of 0.15mg/L and 10%, respectively. Then, denitrification efficiency considerably decreased. Consequently, it was represented that the control of DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent can assure effective denitrification.

• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.553-562
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• 2017

In these days, agricultural reservoirs are considered as a useful resource for recreational purposes, tour and cultural amenity for vicinity communities as well as irrigation water supply. However, many of the agricultural reservoirs are showing a eutrophic or hyper-eutrophic state and high level of organic contamination. In particular, about 44.7% of the aged agricultural reservoirs that constructed before 1945 exceed the water quality criteria for irrigational water use. In addition to external loading, internal nutrient loading from bottom sediment may play an important role in the nutrient budget of the aged reservoirs. The objectives of this study were to characterize variations of thermal structure of a shallow M reservoir (mean depth 1.7 m) and examine the potential of internal nutrient loading by continuous monitoring of vertical water temperature and dissolved oxygen (DO) concentration profiles in 2015 and 2016. The effect of internal loading on the total loading of the reservoir was evaluated by mass balance analysis. Results showed that a weak thermal stratification and a strong DO stratification were developed in the shallow M Reservoir. And, dynamic temporal variation in DO was observed at the bottom of the reservoir. Persistent hypoxic conditions (DO concentrations less than 2 mg/L) were established for 87 days and 98 days in 2015 and 2016, respectively, during the no-rainy summer periods. The DO concentrations intermittently increased during several events of atmospheric temperature drop and rainfall. According to the mass balance analysis, the amount of internal $PO_4-P$ loading from sediment to the overlying water were 37.9% and 39.7% of total loading during no-rainy season in 2015 and 2016, respectively on August when algae growth is enhanced with increasing water temperature. Consequently, supply of DO to the lower layer of the reservoir could be effective countermeasure to reduce nutrient release under the condition of persistent DO depletion in the bottom of the reservoir.