• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.571-574
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• 2003

Three sediment traps were placed at the toe of sloping fields in the alpine belt of Korea and sediment removal efficiency was estimated. Soil texture of the site was sandy soil and 5 runoff and sediment events were observed during 2002. Sediment was largely affected by both the amount and intensity of rainfall. Especially, rainfall intensity seemed to have profound effect on sediment yield from sloping sandy fields. Sediment removal of the sediments ranged widely from 266 kg/ha to 16,974 kg/ha depending on tillage method, slope and slope length, and amount and intensity of rainfall. Sediment removal efficiency was estimated to be more than 98.8%. It was suggested that rational combination of sediment trap and drainage channel might well contribute to control sediment discharge from alpine sloping fields.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2007년도 추계학술대회 및 제23회 정기총회
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• pp.200-201
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• 2007

The present study was conducted in three fields at Namhae to examine the removal efficiency of organic free, heavy metal immobilized sediment on Cochlodinium polykrikoidesand and on sea water quality. The present study results concluded that removal efficiency was depends on the initial number of red tide cells. There was no drastic change in the sea water quality after sediment spray. For the comparison of effectiveness of betonite, zeolite and lime were mixed with sediment did not show any marked difference in removal. Finally, the present study evaluated 50g/$m^{2}$ sediment is sufficient to remove 100% cells density, even though various environmental factors are interfering the mechanism.

• 한국산업융합학회 논문집
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• 제4권1호
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• pp.51-60
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• 2001

This study examines the effects of removal of the sediment protection weir at Taehwa river mouth on hydraulic and around river environment considering the fact that the effects of the sediment protection weir which is installed to protect water level drop of Ulsan harbor caused by sediments according to flood in Taehwa river, Dong-chun, and so forth may add water quality contamination by flow stagnance in normal and drought period and accumulation of pollutants. The result is as follows. First, it is estimated from the examination of variation characteristics water depth and level for Taehwa river before and after removal of the sediment protection weir that about 0.01m of water depth down according to removal of the sediment protection weir occurs when low flow runs between the sediment protection weir which is located about 2.3km away from the estuary and Samho-gyo which is about 9.0km away from the sediment protection weir, and about 0.01~0.56m(directly upstream point of the sediment protection weir 0.56m, Myongchon-gyo 0.14m, Ulsan-gyo 0.03m, and Taehwa-gyo 0.02m) downs when design flood flows between the sediment protection weir and the upstream of Taehwa-gyo which is 10km away from the sediment protection weir. Therefore, it is thought that variation of hydraulic characteristics of water depth down and so on according to removal of the sediment protection weir is slight because water depth variation is only about 1cm between directly upstream point of the sediment protection weir and Samho-gyo. Next, it is estimated from the examination of variation characteristics of flow velocity for Taehwa river before and after removal of the sediment protection weir that about 0.0lm/s of flow velocity increase occurs between the directly upstream point of the sediment protection weir which is about 2.4km away from the estuary and the directly upstream point of Samho-gyo when low flow runs, and about 0.01~0.44m/s increases between the sediment protection weir and Samho-gyo when design flood flows. Therefore, riverbed erosion by the increased flow velocity is concerned but it is thought that the concern about riverbed erosion is not great because the mean velocity is about 0.07~1.36m/s when low flow runs, and about 1.02~2.41m/s when design flood flows for the sector which experiences the flow velocity variation.

• 한국환경과학회지
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• 제11권3호
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• pp.191-199
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• 2002

In this study, water protection reservoir is selected as the target which is located at the estuary of Taehwa river to analyze and examine the effects of hydraulic structure on river environment. This study aims at the definition of factors which cause the change of ecological environment of river due to the effects of the sediment protection reservoir, and the proposal of the direction of environmental friendly river space development through the analysis and examination of stream variation conditions and riverbed variation characteristics among many effects of hydraulic structure on river environment before and after removal of the sediment protection reservoir when design flow is yielded. Firstly, in case of removal the existing sediment protection reservoir, the hydraulic variation characteristics like depth drop due to removal of the sediment protection reservoir are thought of little because it is examined that depths drop with about 0.01m and 0.01~0.56m when low flow is yielded and design flood yielded, respectively. Nextly, as the examination result of the variation characteristics of flow velocity in case of removal the existing sediment protection reservoir, it is thought that the concern about riverbed erosion is not serious according to the analyzed result as the mean velocity of the channel section where the velocity varies in case of removal the sediment protection reservoir is about 0.07~1.36m/s when low flow is yielded, and is about 1.02~2.41m/s when design flood is yielded despite riverbed erosion is concerned as it is examined that flow velocity is getting increase as about 0.01m/s when low flow is yielded and about 0.01~0.44m/s when design flood is yielded. Lastly, from the prediction result of riverbed variation for each flow amount condition before and after removal the sediment protection reservoir, it is known that the variation range of riverbed is nearly constant when flow amount of the channel exceeds a specific limit as it is analyzed that the more flow amount, the more erosion and sediment in the channel section of down stream part of the sediment protection reservoir and the sediment protection reservoir~Samho-gyo, and the variation ranges according to flow amount between flood condition and design flood condition have little difference in the channel section of the upstream of Samho-gyo.

• 한국물환경학회지
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• 제34권3호
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• pp.301-307
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• 2018

This study investigated the effects of sediment removal on water quality and phytoplankton development by setting up mesocosms at Uiam Lake, South Korea, and analyzing the environmental parameters and phytoplankton communities between June and October 2015. The comparison between testbed without sediment removal (TB-1) and testbed after sediment removal (TB-2) gave similar values for water temperature, pH, dissolved oxygen (DO), and electrical conductivity. Nevertheless, the average electrical conductivities of the two testbeds were $139{\mu}S/cm$ and $135{\mu}S/cm$, which were lower than the value obtained from the external control point (TB-con; $154{\mu}S/cm$). The small difference in total phosphorus (TP) and total nitrogen (TN) concentrations between the two testbeds implied that sediment removal did not greatly reduce nutrients; however, the phytoplankton cell count had decreased by approximately 37 % in TB-2 (average 1,663 cells/mL) compared to TB-1 (average 2,625 cells/mL). Compared to TB-con, the phosphorus and nitrogen concentrations of the two testbeds had decreased by 39 % and 30 %, respectively, whereas the phytoplankton abundance had decreased by up to 73 %, perhaps because of the blocked inflow of nutrients and the stabilized body of water caused by the installation of the mesocosm. The concentration of geosmin was lower in testbeds than in the external point, because installation of the structures had reduced the cyanobacteria biomass.

• 한국해양생명과학회지
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• 제3권1호
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• pp.38-43
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• 2018

대형저서동물에서 우점하고 있는 갯지렁이류는 퇴적층의 유기물 섭취를 통하여 저질환경개선에 중요한 역할을 한다. 본 연구에서는 최근 양식기술이 개발된 바위털갯지렁이를 이용하여 갯벌 퇴적층의 유기물 제거효과를 검토하였다. 이를 위하여 입자특성이 다른 세종류의 저질환경(S1: 강사질, S2: 해사질, S3: 니사질)에서 해수 및 퇴적층의 TOC를 측정하였다. 바위털갯지렁이는 세종류의 입자특성에서 모두 유기물 제거효과를 나타내었으며, 입자가 클수록 제거율이 높았다. 유기물 정화능력을 정량적으로 평가한 결과 바위털갯지렁이는 각 저질별로 강사질에서 3.9856 ppm g^-1d^-1, 해사질에서 2.8021 ppm g^-1d^-1, 그리고 니사질에서 28.1142 ppm g^-1d^-1의 제거능력을 나타내었다. 본 연구결과는 바위털갯지렁이가 다양한 저질에서 유기물 제거에 기여하고 있음을 보여 주었다.

• 환경정책연구
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• 제9권2호
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• pp.41-55
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• 2010

댐은 사회전반에 걸쳐 많은 편익을 제공하고 있다. 이를 위해서는 일정수준 이상의 저수용량 확보가 필수적이다. 그러나 상류의 토사 유입으로 인하여 댐의 저수용량은 줄어들고 있는 실정이다. 전 세계적으로 5조 톤의 토사가 매년 댐 뒤에 쌓이는 실정이다. 강이 여러 지역에 걸쳐 흐르는 경우 상류의 농업에서 발생하는 토사는 장시간에 걸쳐서 지속적으로 발생하기 때문에 상류 농업종사자들은 관리를 소홀히 하는 경향이 있다. 특히 토사는 댐의 저수용량을 지속적으로 줄여 궁극적으로는 댐의 경제적 가치를 소멸시키는 효과가 있다. 따라서 상류 지역의 토사저감 노력과 함께 댐의 저수용량 확보가 급선무이다. 실증분석으로 나일강 상류의 수단 농업지역과 하류의 이집트 Aswan High Dam을 분석하였다. 실증분석 결과 상류 농업부문의 토사저감 노력과 댐의 토사제거 방안이 사회전체의 경제적 편익을 극대화하는 것으로 나타났다. 동태적 최적제어이론을 이용한 유역토사관리 모형에서 댐의 경제적 편익을 포함한 사회전체의 편익은 크게는 약 1,510억 달러로 추산되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권4호
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• pp.77-86
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• 2020

Persulfate-based advanced oxidation processes (AOPs) can oxidize various organic pollutants. In this study, persulfate/Fe(II) system was utilized in phenol removal, and the effect of various organic and inorganic chelators on Fe(II)-medicated persulfate activation was investigated. The feasibility of persulfate/Fe(II)/chelator in cleanup of phenol-contaminated sediment was confirmed through toxicity assessment. In persulfate/Fe(II) conditions, the rate and extent of phenol removal increased in proportion to persulfate concentration. In chelator injection condition, the rate of phenol removal was inversely proportional to chelator concentration when it was injected above optimum ratio. Thiosulfate showed greater chelation tendency with persulfate than citrate and interfered with persulfate access to Fe(II), making the latter a more suitable chelator for enhancing persulfate activation. In contaminated clay sediment condition, 100% phenol removal was obtained within an hour without chelator, with the removal rate increased up to four times as compared to the rate with chelator addition. A clay sediment toxicity assessment at persulfate:Fe(II):phenol 20:10:1 ratio indicated 71.3% toxicity reduction with 100% phenol removal efficiency. Therefore, persulfate/Fe(II) system demonstrated its potential utility in toxicity reduction and cleanup of organic contaminants in sediments.

• 한국환경과학회지
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• 제11권4호
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• pp.309-317
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• 2002

In this study, water protection reservoir is selected as the target which is located at the estuary of Taehwa river to analyze and examine the effects of hydraulic structure on river environment. This study examined the water quality variation characteristics among many effects of hydraulic structure on river environment before and after removal of the sediment protection reservoir when low flow is yielded. This study aims at the definition of factors which cause the change of ecological environment of river due to the effects of the sediment protection reservoir, and the proposal of the direction of environmental friendly river space development through the comparison of stream variation conditions(depth, velocity, and etc.) and riverbed variation characteristics with ecological depth condition of Taehwa-river's channel for each representative species of fish and examination those. Firstly, from the examination result of water quality when low flow is yielded before and after removal of the sediment protection reservoir for problems about water quality of river due to flow amount decrease in river, it is found that DO decreases about 0.78~0.86ppm at the lower stream of Myeongchon-gyo, and BOD decreases about 0.06~0.24ppm from right upper stream to the direction of estuary when the sediment protection reservoir is removed. It is known from the above that there is some improvement of water quality from the lower stream of Taehwa-gyo to the estuary in case of removal the sediment protection reservoir. Nextly, it is thought that the effects on ecosystem due to water depth and draw down in channel is not serious on the basis of the examination of water quality analysis result according to removal of sediment protection reservoir and hydraulic depths for reservation of ecosystem, these are 10~40cm for breeding season, 10~50cm for fry period, and 10~100cm for adult period of the representative species of fish in Korea.

• Membrane and Water Treatment
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• 제8권5호
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• pp.423-435
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• 2017

Settling Basins are one of the most important and popular methods for removal of suspended sediments irrigation and drainage networks or power canals taking off from an alluvial river and wastewater treatment plant. Improving the performance and so increasing sediment removal efficiency of settling basins by an alternative method is necessary. In the present work, the effect of baffle and its angle of attack with the flow (${\theta}$) on the sediment removal efficiency is investigated by conducting a series of experiments on a straight canal with 8 m length, 0.3 m width and 0.5 m height and 3 m length of basin equipped with an adjustable glass baffle. A numerical analysis has been carried out using ANSYS Fluent 3D software (a general purpose computational fluid dynamics simulation tool) for three Froude numbers from the experiments. The numerical and experimental results were found to match reasonably well.