• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2007년도 학술발표회 논문집
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• pp.1287-1292
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• 2007

Recently, the frequency of unexpecting heavy rains has been increased due to abnormal climate and extreme rainfall. There was a limit to analyze 1D or 2D stream flow that was applied simple momentum equation and fixed energy conservation. Therefore, hydrodynamics flow analysis in rivers has been needed 3D numerical analysis for correct stream flow interpretation. In this study, CFD model on FLOW-3D was applied to stream flow analysis, which solves three dimenson RANS(Reynolds Averaged Navier-Stokes Equation) control equation to find out physical behavior and the effect of hydraulic structures. Numerical simulation accomplished those results was compared by using turbulence models such as ${\kappa}-{\varepsilon}$, RNG ${\kappa}-{\varepsilon}$ and LES. Those numerical analysis results have been illustrated by the turbulence energy effects, velocity of flow distributions, water level pressure distributions and eddy flows around the piers at Jangwall bridge in urbarn stream.

• 한국조경학회지
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• 제27권4호
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• pp.39-49
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• 1999

Urban streams have, recently, been straightened and widened to alleviate flooding problem. As a result, the stream have been modified inadvertently for ecological functions and microtopography. In this study, we investigated riparian vegetation and microtopography of the tributaries of Han River before and after the monsoon rain in summer. The purpose of this study was to relate the stream microtopography to the distribution of riparian vegetation. The stream microtopography was investigated for its scale and pattern. Vegetation was investigated from 131 plots by Braun-Blanquet method. The distribution of riparian vegetation was significantly correlated with the stream microtopography. Various herbaceous species occurred at stream bank slop, high terrace and channel side. However, at channel side and concave part of terrace where soils were in high moisture level, only a few wetland species were dominated. The complexity of the microtopography in the stream corridors led to heterogeneous riparian vegetation. The vegetation showed more stability against flooding at the stream corridors with natural and complex microtopography than at the urban-type stream corridors with simple topographical features. The results showed that the development of riparian vegetation was influenced by the changes in microtopography, which was primarily determined by the shape and characteristics of channel. It seemed that a close-to-nature river system would be restored more readily with an understanding of microtopographical features affecting the distribution of riparian vegetation.

• 상하수도학회지
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• 제20권4호
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• pp.573-584
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• 2006

This study was carried out to investigate the causes of fish kills in the Yudeung Stream in Daejeon, Korea using literature reviews, governmental and our water quality monitoring data of the study site, rainfall data, intensive water quality monitoring during rainfall events, sediment pollutant contents and laboratory bioassay tests. Fish kill in urban streams can be caused by combined effect of reduction in dissolved oxygen concentration, increase in toxic material or increase in turbidity in waterbody due to introduction of surface runoff or effluent of combined sewer overflows after rainfall from the watershed areas. Despite of extensive and intensive field surveys and laboratory tests, it was found that those conventional methods have limitations to identify causes of fish kills in urban streams. It would be necessary to use dynamic water quality modeling to predetermine the range and level of water pollution in the stream and automatic water quality monitoring system that can collect water samples and detect water quality continuously.

• 한국환경과학회지
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• 제14권1호
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• pp.33-40
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• 2005

The size of minimum order stream has a very sensitive effect on runoff analysis model using the divergence characteristic of stream. Therefore, in this study, the threshold area of minimum order stream has been examined the change characteristic of topographical parameters. The subject basin of the research was the upper basin of the Kumho water gage station which is located in the middle of the Kumho river. The 1:25,000 numerical geography which was constructed $10{\times}10m$ mesh was used. The range of investigation of topographical parameters are number of stream order, length, area, slope, basin relief, sinuosity ratio, drainage density and total stream length etc. It was found from the result of analysis that the threshold value of minimum order stream has a very big effect on topographical parameters of basin. It was found that the threshold area of minimum ord er stream revealed under $0.10km^{2}.$ Furthermore, the parameters showed a serious change except for over $0.10km^{2}.$

• 한국조경학회지
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• 제31권4호
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• pp.67-73
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• 2003

Natural stream work has been implemented recently to improve the urban stream environment in Korean cities. Many plants planted in the early work have not survived because they were not suited to the site and therefore failed to adapt to the riparian environment. The objective of this study is to investigate the floral change at the riparian environment after completion of the natural stream work by comparing the differences between planted species during the work and the current species at the study site. The study site was the stream area between Yeongdohng 2 bridge and Yeongdohng 3 bridge at Yangjae-cheon Stream, Gangnam-ku, Seoul, which was the prototype site of G-7 project of the Ministry of Environment in Korea. The following conclusions were derived after doing this study: Among the 50 species planted during the work, 23 species survived in the stream zone, while 27 species did not. The species that did not survive were ornamental plants that were not appropriate for the riparian environment. Among the 144 species which appeared naturally, 77 species(53.5%) were annuals and perennials, which means the study site is still in ecological disturbance and does not have a stable status ecologically. Thus, it is necessary to select the plant species that can survive in the disturbed riparian environment.

• Environmental Engineering Research
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• 제21권2호
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• pp.211-218
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• 2016

Cheonggye-cheon is a partly restored urban stream located in central Seoul. We monitored fecal contamination using three different fecal indicators, total coliforms (TC), fecal coliforms (FC) and E. coli, to assess differences in each indicator on days of varying weather conditions. Presumptive TC, FC and E. coli colonies were identified by their 16S rRNA sequences. The results showed that enumeration of E. coli provided a better reflection of fecal contamination of the stream than TC and FC. The main sources of contamination were the inflow of fecal-polluted groundwater from the vicinity of a subway line and two inflowing streams. The fecal contamination was worsened on days with heavy rain because untreated sewage from a collecting facility flowed into the stream. Moreover, growth potential of fecal indicator (E. coli) in situ induced by algal exudates was measured. Our results suggest that an appropriate standard based on E. coli rather than TC and FC should be established for improving water quality management strategies of Cheonggye-cheon in the future.

• 한국환경과학회지
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• 제28권2호
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• pp.235-248
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• 2019

The purpose of this study is to quantitatively analyze the effects of a restoration project on the decrease in the temperature in the surrounding areas. The thermal environment characteristics of the investigation area were analyzed using the meteorological data from the Busanjin Automatic Weather System which is closest to the target area. The terrain data of the modeling domain was constructed using a digital map and the urban spatial information data, and the numerical simulation of the meteorological changes before and after the restoration of the stream was performed using the Envi-met model. The average temperature of the target area in 2016 was $15.2^{\circ}C$ and was higher than that of the suburbs. The monthly mean temperature difference was the highest at $1.1^{\circ}C$ in November and the lowest in June, indicating that the temperatures in the urban areas were high in spring and winter. From the Envi-met modeling results, reductions in temperature due to stream restoration were up to $1.7^{\circ}C$ in winter, and decreased to $3.5^{\circ}C$ in summer. The effect of temperature reduction was seen in the entire region where streams are being restored.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.787-790
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• 2008

SWAT(Soil and Water Assesment Tool) 모형은 장기간에 걸친 토양과 토지이용 및 관리 상태에 따라 복잡하게 반응한 대규모 유역의 물과 토사유출 및 농업화학물질로 인해 실제 토지관리가 수환경에 끼치는 영향을 예측하기 위하여 개발되었다. 일반적으로 하천은 유역의 개발 정도에 따라 도시하천과 자연하천으로 나뉘며 도시하천의 경우 도시화가 진행됨에 따라 토지이용상태 및 토지피복상태의 변화로 불투수면적이 증가함에 따라 도시하천의 건천화가 급속도로 진행된다. 본 연구에서는 장기유출모의가 가능한 SWAT 모형을 이용하여 도시하천의 유출량을 모의하고 특히 유역의 규모가 작은 소유역의 SWAT 모형의 적용성을 제시하고자 한다. GIS와 연계한 SWAT 모형을 이용하여 조만강 유역을 모의하였고, 모형의 민감도 분석을 통해 매개변수를 최적화시킴으로서 모델의 신뢰도를 평가하고자 하였다.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.687-690
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• 2008

Currently, Stream flow analysis has been accomplished by one or two dimensional equations and was applied by simple momentum equations and fixed energy conservations which contain many reach uppermost limit. In this study, FLOW-3D using CFD(Computational Fluid Dynamics) was applied to stream flow analysis which can solve three dimensional RANS(Reynolds Averaged Navier-Stokes Equation) control equation to find out physical behavior and the effect of hydraulic structures. Numerical simulation accomplished those results was compared by using turbulence models such as $k-\varepsilon$, RNG(Renomalized Group Theory) $k-\varepsilon$ and LES(Large Eddy Simulation). Numerical analysis results have been illustrated by the turbulence energy effects, velocity of flow, water level pressure and eddy flows around the side overflow type structures at Jangwall bridge in urban stream.

• 한국생태학회:학술대회논문집
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• 한국생태학회 1999년도 국제 Symposium 및 '99 춘계 공동 학술 발표대회
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• pp.77.2-77.2
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• 1999