• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.361-361
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• 2016

기상이변으로 인하여 최근 10년 동안 해마다 홍수와 가뭄 피해가 극심하였고 그에 따른 경제적 손실 또한 증가하고 있다. 이에 우리나라에서는 4대강 살리기 사업으로 다기능보 건설 및 준설을 통하여 용수확보 및 홍수조절능력을 향상시키고자 하였다. 하지만 그로인해 하천환경이 많이 변하였으며, 그에 따른 하도의 안정성 확보 및 효율적인 유지관리가 요구되는 상황이다. 체계적인 하천관리를 위해서는 24시간/365일 하천상황 분석과 함께 실시간 수리학적 체류시간 분석 등을 통한 하천 및 하도내 수자원 관리 기초자료 필요성이 요구된다. 따라서 본 연구에서는 변화된 하천을 정확히 반영하고, 보의 운영조건을 고려한 2차원 수리해석을 실시하여 하천관리를 위한 기초 자료를 제공하고자 한다. 다기능보의 지형조건과 운영조건을 반영할 수 있는 EFDC 모형을 이용하여 낙동강에 대해 2차원 수리모형을 구축하였다. 자료기반모형을 이용하여 지류 유입량을 예측하여 적용하였으며, 보 상류 및 하류부 수위를 상 하류단 경계조건으로 구성하였다. 이를 통해 보별 유입량 및 보 상류의 주요지점의 수위, 유량에 대한 다양한 조건을 확정론적 방법과 추계학적 방법으로 분석하여 주요지점에서의 유량 및 수위 수문곡선, 수위/유량 종단양상, 주요지점별 도달 시간 등을 제시하였다. 또한 확정론적 수위 및 유량의 홍수기 및 저 갈수기, 계절 및 분기, 일단위및 시단위 등의 시계열 결과를 도출하였으며, 유량규모별 전파 양상을 분석하여 강우-유량-도달 시간의 조건표를 제시하여 보의 운영에 직접적으로 활용할 수 있도록 하였다. 본 연구를 통해 낙동강에서의 하천관리를 위한 기초자료를 제공할 수 있으며, 다양한 조건에 대한 보 운영 및 하천 유지관리의 가이드라인을 제시할 수 있을 것으로 판단된다.

• Journal of Wetlands Research
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• v.26 no.3
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• pp.245-253
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• 2024

Blue-green algal bloom, or harmful algal bloom has a negative impact on the aquatic ecosystem and purified water supply system due to oxygen depletion in the water body, odor, and secretion of toxic substances in the freshwater ecosystem. This Blue-green algal bloom is expected to increase in intensity and frequency due to the increase in algae's residence time in the water body after the construction of the Nakdong River weir, as well as the increase in surface temperature due to climate change. In this study, in order to respond to the expected increase in green algae phenomenon, an algal bloom forecast system based on hydro-meteorological factors was presented for preemptive response before issuing a algal bloom warning. Through polyserial correlation analysis, the preceding influence periods of temperature and discharge according to the algal bloom forecast level were derived. Using the decision tree classification, a machine learning technique, Classification models for the algal bloom forecast levels based on temperature and discharge of the preceding period were derived. And a algal bloom forecast system based on hydro-meteorological factors was derived based on the results of the decision tree classification models. The proposed algae forecast system based on hydro-meteorological factors can be used as basic research for preemptive response before blue-green algal blooms.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.603-610
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• 2009

This research was performed to improve removal efficiency of toluene and methyl ethyl ketone (MEK) using Candida tropicalis, one of the yeast species. An airlift loop bioreactor (ALB) was employed to enhance the capability of mass transfer for toluene and MEK from the gas phase to the liquid, microbial phase. Polymer gel media made from PAC, alginate and PEG was applied for the effective immobilization of the yeast strain on the polymer gel media. The experimental results indicated that the mass transfer coefficient of toluene without polymer gel media was 1.29 $min^{-1}$ at a gas retention time of 15 sec, whereas the KLa value for toluene was increased to 4.07 $min^{-1}$ by adding the media, confirming the enhanced mass transfer of volatile organic compounds between the gas and liquid phases. The removal efficiency of toluene and MEK by using yeast-immobilized polymer gel media in the ALB was greater than 80% at different pollutant loading rates (5, 10, 19 and 37 g/$m^3$/hr for toluene, 4.5, 8.9, 17.8 and 35.1 g/$m^3$/hr for MEK). In addition, an elimination capacity test conducted by changing inlet loading rates stepwise demonstrated that maximum elimination capacities for toluene and MEK were 70.4 and 56.4 g/$m^3$/hr, respectively.

• KSBB Journal
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• v.15 no.5
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• pp.469-473
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• 2000

We studied the removal of toluene vapors in a lab-scale biofiter. Biofiltration was performed in a column fed in a downflow manner with contaminated air at ambient conditions. The column was packed with a mixture of peat and calstone(5:3 vol. Ratio), which was inoculated with microbes of selected stains(Pseudomonas putida type A). The microorganisms were immobilized on the filter media and biofilms were formed. The fiofilter was operated at various inlet toluene concentrations for days, and treated up to a maximum elimination capacity of $20 g/m^3hr$ at an inlet load of $30 g/m^3hr$, which corresponds to removal efficiencies in the range 20∼90% and a gas retention time of 1 to 2 min. The pressure drop was almost negligible over the biofilter columns, amounting to only $1.062 cmH_2O/m$ and appreciably smaller than other studies. The effects of operating conditions such as flow rate, inlet toluene concentration and moisture content on the performance of the biofilter were sequentially investigated.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.449-449
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• 2018

최근 국내 하천과 호수에서 수온상승 및 기후변화로 인한 녹조발생이 빈번하게 나타남에 따라 녹조발생원인과 예측에 대한 중요성이 빠르게 인식되어가고 있다. 이에 본 연구에서는 보 구간의 연직 수온분포를 분석하고, 측정된 수온분포와 유해 남조류 세포수를 바탕으로 수체안정화도와 남조류의 발생을 비교하였다. 낙동강수계의 8개보를 선정하여 2015년 1월부터 2016년 12월까지 주 1회, 수심 1m 간격으로 측정한 수온을 분석했으며, 유해 남조류 세포수는 환경부 조류경보제 및 수질예보제에서 측정한 자료를 사용하였다. 수온 모니터링 분석 결과 2015년과 2016년 모두 5월 이후 수온성층이 형성되었고, 8월에 비교적 강한 수온성층이 형성되는 것으로 나타났다. 특히 칠곡보와 강정고령보에서 상대적으로 뚜렷하게 나타났는데 이는 수심이 깊고 체류시간이 긴 지형적 특성에 의한 것으로 판단된다. 형성된 수온성층은 안정된 상태로 지속되지 않고 주로 강우 시에 상 하층간의 수온구배가 줄어들어 혼합되는 전도현상이 관찰되었다. 수체안정화도 산정 결과 역시 2015년, 2016년 모두 수온성층 결과와 비슷하게 5월에 수체안정화도가 급증하다 9월 이후에 크게 감소하는 경향을 보였으며, index별로 Schmidt stability, Bouyancy Frequency 항목에서 이러한 경향이 뚜렷하게 나타났다. 또한 5월 이후 수체안정화도가 증가하는 시기에 남조류 세포수의 현존량도 증가하는 것으로 관찰되어 남조류의 발생과 수체안정화도의 증가는 시기적으로 일치하는 것으로 나타났다. 수체안정화도와 남조류 세포수와의 상관성은 2016년이 높았으며 그중 강정고령보에서 상관계수가 Schmidt stability는 0.78, Bouyancy frequency는 0.65로 높은 상관성을 나타내었다. 하지만 2015년의 경우 9월 이후 수체안정화도와 수온이 감소하였지만 남조류 세포수는 증가하여 경향이 일치하지 않는 것으로 나타났는데, 이는 저수온성의 남조류가 우점했기 때문인 것으로 판단된다. 향후 조류 발생 및 예측 등을 효과적으로 재현하는데 있어 자료로 활용하기 위해서는 지속적인 수질 모니터링 및 기상인자 모니터링이 필요할 것으로 판단된다.

• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.470-478
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• 2017

This study was classified into two groups, normal season group and drought season group, by the cluster analysis using the weather and water quality data from 2012 to 2015, using SPSS 18 version. Also each cluster was classified into three spaces, Gangcheon, Yeoju and Ipoh weir. We performed the multiple regression analysis with each monthly data that concentration of Chl-a was more than algae warming level. 6 groups classified in time and space were analyzed by the correlation analysis between concentration of Chl-a and 3 weather, 11 water quality and discharge factors. We developed Chl-a prediction equations of each group with independent variables of the multiple regression analysis applying to the correlation result. The result of cluster analysis was that the period was divided into two groups, normal group(2012-2013) that total annual precipitation rate was normal and drought group(2014-2015) that total annual precipitation rate was less than 1,000 mm/hr, in time. The months that concentration of Chl-a was more than algae warming level in each group classified by cluster analysis were that the normal group was 3~8 and drought group was 3 and 6~10. The correlation result between Chl-a and weather, water quality and discharge factors for each 6 group was that relationships between Chl-a and water, discharge factors were high in the drought group more than in normal group at all weirs. This was influenced by velocity reduction and increasing HRT according to the intense drought. Weather, water quality and discharge factors that were high correlation with Chl-a were applied to independent variables of Chl-a prediction equations and each equations were developed. Among them, Each adjusted R square of Prediction equations for Chl-a in each group at Ipoh weir where is located in Namhan river downstream and is directly connected to Paldang dam were normal group = 0.920 and drought group = 0.818. It's showed the high linear.

• Korean Journal of Environment and Ecology
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• v.31 no.2
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• pp.266-274
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• 2017

The purpose of this study was to analyze the number of visitors to the top of Seoseokdae in Mudeungsan National Park, in which visitors are concentrated, and their visiting patterns, thereby suggesting measures to manage the visitors. The number of annual visitors and the numbers of regional and seasonal visitors to Mudeungsan National Park, which affect the concentration of visits to Seoseokdae were analyzed using the data produced by an automatic digitizing device. A field study was conducted to examine the number of seasonal and periodic visitors to Seoseokdae and their visiting patterns. In 2015, the number of visitors was 2,563,651 and 83.9% of the visitors visited via the Jeungsimsa and Wonhyosa area that is near Gwangju City. This area is close to the Seoseokdae area and it is easy to hike between the areas. Therefore, there was an influx of most visitors to Seoseokdae into the Jeungsimsa and Wonhyosa area. In terms of seasonal visitors, the largest number of visitors came in the fall, followed by the summer, spring, and winter in order. However, the seasonal differences were not notable. There was no statistically significant correlation between the number of visitors and meteorological factors. This result may have been because Gwangju citizens frequently visit Mudeungsan regardless of period and weather. Visitors can get to Seoseokdae via the trails into Wonhyosa and Jangbuljae. A slightly larger number of visitors used the trail into Jangbuljae in the fall and winter, whereas a larger number of visitors used the trail into Wonhyosa in the summer. In general, there is a large influx of visitors into Jangbuljae, a strategic visiting point. However, a slightly larger number of visitors may have chosen the trail into Wonhyosa in the summer because they could hike under the shade of trees. In the summer, visitors stayed in Seoseokdae for a short time with a low level of crowdedness. On the other hand, in the fall and winter, visitors stayed in the area longer because they had lunch and rested. During the time, the number of momentary maximum visitors peaked, causing extreme crowdedness. Therefore, some visitors showed the visiting pattern of entering the grassland outside the designate zone. Because this behavior can damage the grassland on the top of Seoseokdae, which can lead to soil erosion, intensive visitor management may be necessary.

• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.278-288
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• 2012

The zooplankton community of Lake Paldang, Korea, was investigated on a weekly basis from 2004 to 2006. The seasonal succession of zooplankton community structure was influenced by hydrological factors such as rainfall pattern and efflux in Lake Paldang. According to the monsoon climate, spring, fall and winter had reduced precipitation, so that zooplankton dynamics of the lake showed a typical succession pattern. In spring, small sized and faster growing rotifera rapidly increased, and copepods and cladocera noticeably increased thereafter. Rotifera dominated the zooplankton community, occupying more than 90% of total zooplankton abundance. Among rotifera, Keratella cochlearis was extremely dominant in spring. Copepoda were mainly present as Copepodid and Nauplius. Among cladoceran species, Bosmina longirostris was dominant. In summer, during the rainy season, zooplankton were flushed out by an associated dam. After the rainy season, rotifera increased rapidly when the water column of the lake was stable. During the fall, zooplankton abundance gradually reduced in accordance with decreasing water temperature. However, the occupation rate of copepod (Copepodid, Nauplius) increased relatively. Zooplankton dynamics were influenced by meteorological changes and hydraulic-hydrological factors, because Lake Paldang is a completely closed ecosystem.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.707-720
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• 2011

For the lake case, the detention phenomenon of water body occurs and stays for a long time. Especially, following the layer of water depth direction, the lake body and water quality problems are different from the water quality of river. So according to time, the stream and water quality can be simulated by the 3-Dimensional Model, which can divide water layer for reservoir or lake. The water quality simulation result will become more reliability. For this study, the 3-Dimension Model - EFDC was used to simulate water quality of Unam reservoir in the Sumjin Dam. The HEC-GeoHMS and HEC-HMS Rainfall - Runoff Model based on GIS were used to estimate long-term runoff, and input data was constructed to the observed water level, meteorological data, water temperature, T-N and T-P. In order to apply the EFDC model, water depth was divided into 3 layers and 5,634 grids were extracted. After constructing the grid net, the water quality change of Unam reservoir in time and space was simulated. Overall, long term runoff simulation reflected the actual observed runoff well, through the water quality simulation, according to the pollution factors, the behavior characteristics can be checked, and the simulated water quality can be properly reflected. The function of EFDC has been confirmed, which water quality can be properly simulated. In the near future, to establish countermeasures for Intake Facilities of Watershed and Management, this support which some basic tools can be applied is in expectation.

• Journal of Environmental Impact Assessment
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• v.23 no.5
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• pp.406-416
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• 2014

When abnormal taste and odor were detected in the tap water of the North-Han river watershed during the dry season in late 2011, excessive nutrients with algal growth in the Lake Uiam and weather factors were considered to be among its causes. The nutrients, in particular, originated from domestic sewage in the Chuncheon area. This study was conducted to investigate relations between the algal growth in the Lake Uiam and the contribution of nutrients from public sewage treatment works (PSTWs) in Chuncheon city, and based on this to analyze the environmental impact. Nutrients in the Lake Uiam have already been accumulated to the level of eutrophication. Even in winter, the conditions in the lake such as retention time and water temperature were favorable to boost algal growth. After phosphorus treatment processes were introduced, the PSTWs in the Lake Uiam watershed were able to reduce the total phosphorus loads by 43%. The algal concentrations in the Lake Uiam also dropped by about 7%. The nitrogen treatment efficiencies in the PSTWs, on the other hand, remained almost the same after the introduction of the phosphorus treatment processes. To solve these problems more efficiently, it is necessary to develop management strategies for the upstream area of the Lake Uiam and set plans to improve nitrogen treatment operation and management for the PSTWs in Chuncheon.