• 한국수자원학회논문집
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• 제51권8호
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• pp.713-727
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• 2018

본 연구는 국내 하천의 고유성을 반영할 수 있는 물리적 환경평가 체계를 개발하는 것이다. 하천유형 분류, 평가구간 선정, 평가 항목 및 지표에 대하여 종합적으로 요약하였다. 하천의 물리적 구조는 하천 유수력에 의한 반응의 결과이므로 하도경사, 하상재료의 입경 및 하도지형의 특성에 따라 하천을 3가지 유형으로 분류하였다. 평가구간은 각 하천 유형의 대표적인 특징인 step 또는 여울출현 간격, 사행도에 따라 저수로 폭의 10배와 25배 기준으로 선정하였다. 평가지표는 하도 안정성, 흐름 상태, 횡단면 형상, 하안 안정성, 하도개수 및 하천횡단구조물과 같은 공통지표와 유효 서식지, 하상 매몰도, 흐름의 다양성 및 step과 여울 출현빈도와 같은 하천 유형별 특성지표로 구성되어 있다. 적용성 검토를 위하여 개발된 평가체계를 9개의 하천에 적용하고 그 결과를 제시하였다.

• 한국환경복원기술학회지
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• 제16권1호
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• pp.207-225
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• 2013

Current ecological stream restoration is focusing on recovery of physical characteristic and ecological functions of individual stream. For effective stream restoration, the relationship between stream environment and riparian flora should be investigated. The purpose of this study is to analyze the relationship between disturbance of hydromorphological structures and naturalized plants ratio in small to mid-sized streams. For the study sites, Gwanpyeong stream, Dongdal stream, and Yongchoo streams were chosen as 'reference stream' while, Gunnam stream, Anchang stream, and Hwa stream were chosen as 'damaged stream'. The hydromorphological structures of streams were evaluated with LAWA and flora of the streams were completely enumerated to calculate naturalized plants ratio. The result showed that there was a significant correlation between the outcome of LAWA and naturalized plants ratio(r=0.675, p<0.01). The result of factor analysis of LAWA identified three factors, 'River front and land use', 'River bed materials and structures', and 'Crossing structure and bar'. Among the factors of hydromorphological structures given by the result of factor analysis, 'river front and land use' and 'bed materials and structures' have statistically significant relationship with naturalized plants ratio($R^2$=0.470, p<0.01). Given this results, quantitative analysis on the relationship between disturbance of hydromorphological structures of streams and naturalized plants ratio could provide some essential information for stream restoration. Also, as this study figured out major factors of hydromorphological structures that affect naturalized plants ratio, it might help monitor ecological states and current problems of small and mid-sized streams.

• 한국환경복원기술학회지
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• 제3권4호
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• pp.84-90
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• 2000

The objective of this study was to introduce the current status and development strategy for an environmental restoration of stream side in Japan, and to consider a methodology which could be effectively applied for the environmental restoration of stream side in Korea. 1. In order to change the recent direction of the forest conservation and erosion control projects which are focused on the restoration of stream side ecology, we have to quit the past erosion control policy such as water control purpose, and establish new plans regarding on the forest conservation and erosion control which is considered the regional environmental restoration of watershed. 2. When we restore stream side and river side ecosystem, we should establish restoration plans which can keep the original nature of stream and river. 3. The forest conservation and erosion control construction projects for the restoration of stream and river ecosystem should be planned for the perfect restoration of their ecosystem by way of sustainable maintenance and management. 4. The restoration direction of stream and river ecosystem needs to be planned to restore the diversity of small geographies such as waterway, shoal and puddles rather than flattening of stream bed. 5. The main principle in the restoration of stream and river ecosystem is to accomplish forest conservation and erosion control construction projects which can conserve the existing stream and river ecosystem.

• Environmental Engineering Research
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• 제13권3호
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• pp.147-154
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• 2008

The purpose of this study was, as a preliminary step for understanding the whole aspects of the impacts of a weir on the ecosystems in upper and lower streams, to find out the impacts of the weirs with and without a fish-way. A survey on the aquatic ecosystem of upper and lower streams of weirs in Ham-an Stream was carried out from June to October, 2006. Results of the investigation showed that some meaningful effects on the ecosystems had occurred by the weirs. The fish fauna in upper stream of the weir with a fish-way appeared to include 3 families, 8 species, and 184 individuals, while that in the lower stream of the weir appeared to include 5 families, 14 species, and 664 individuals. The fish fauna in the upper stream of the weir without a fish-way appeared to include 3 families, 9 species, 107 individuals, while that in the lower stream of the weir appeared to include 9 families, 19 species, 520 individuals, disclosing that, no matter with or without a fish-way, fish fauna species diversity and size of population were more abundant and bigger in the lower stream than in the upper stream, but that difference of fish fauna species diversities between upper and lower streams of the weirs appeared to be bigger for the weir with a fish-way than for the weir without a fish-way. Benthos species diversity and size of population were found to be more abundant and bigger in lower stream than in upper stream, and in wet season than in dry season.

• 한국지하수토양환경학회지:지하수토양환경
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• 제21권1호
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• pp.61-71
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• 2016

Visual MODFLOW was used for quantifying stream-aquifer interactions caused by seasonal groundwater pumping. A hypothetical conceptual model was assumed to represent a stream-aquifer system commonly found in Korea. The model considered a two-layered aquifer with the upper alluvium and the lower bedrock and a stream showing seasonal water level fluctuations. Our results show that seasonal variation of the stream depletion rate (SDR) as well as the groundwater depletion depends on the stream depletion factor (SDF), which is determined by aquifer parameters and the distance from the pumping well to the stream. For pumping wells with large SDF, groundwater was considerably depleted for a long time of years and the streamflow decreased throughout the whole year. The impacts of return flow were also examined by recalculating SDR with an assumed ratio of immediate irrigation return flow to the stream. Return flow over 50% of pumping rate could increase the streamflow during the period of seasonal pumping. The model also showed that SDR was affected by both the conductance between the aquifer and the stream bed and screen depths of the pumping well. Our results can be used for preliminary assessment of water budget analysis aimed to plan an integrated management of water resources in riparian areas threatened by heavy pumping.

• 대한토목학회논문집
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• 제28권3B호
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• pp.283-296
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• 2008

본 연구에서는 현재의 하천상태를 진단할 수 있는 도시하천 평가기법을 제시하였다. 이를 위해 국내 외 하천평가에 대한 문헌 및 연구자료를 조사하고 비교 분석하였으며, 예비하천조사를 실시하고 도시하천의 특성 및 하천의 치수기능 등을 고려하여 하천의 상태를 평가할 수 있는 평가인자를 도출하였다. 도시하천 평가기법은 상위단계, 중간단계, 하위단계의 3단계로 구성하였다. 상위단계에서 하천의 기능을 고려하여 제방, 하천, 생태환경의 3개 특성으로 구분하고, 중간단계에서는 3개 특성이 변형되고 훼손된 정도를 설명할 수 있는 10개의 평가부문(제방, 수로, 흐름, 하상, 비인공화 정도, 저수로변과 홍수터, 하천주변, 동물상, 식물상, 수질)으로 나누었으며, 하위단계에서는 도출된 53개의 평가항목을 구성요소로하여 단계적 평가가 가능한 평가기법을 제시하였다. 특성간, 평가부문간 가중치를 산정하기 위하여 하천전문가를 대상으로 설문조사를 실시하고, 이를 AHP(Analytic Hierarchy Process)를 이용하여 분석하였다. 하천의 규모와 복원정도를 고려하여 수원천, 안양천, 중랑천을 대상하천으로 선정하고 평가를 실시하여 도시하천 평가기법의 적용성과 평가정보의 가치 수준을 확인하였다. 평가결과는 항목지수, 부문지수, 특성지수, 총괄지수 및 평가등급으로 하천의 상태를 나타냈다. 본 연구에서 제시한 하천평가기법에 따른 하천평가결과는 하천이 변형되고 훼손된 부분과 정도를 파악함으로써 도시하천의 복원과 관리에 필요한 기초자료로 활용되어 질 수 있을 것으로 판단된다.

• 전기전자학회논문지
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• 제18권3호
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• pp.392-397
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• 2014

본 논문은 Memory Latency Penalty를 개선한 SIMT Architecture 기반 Stream Processor의 Memory Operation System Architecture를 제안한다. 제안하는 구조는 Non-Blocking Cache Architecture를 적용하여 기존의 Blocking Cache Architecture에서 발생하는 Cache Miss Penalty를 개선하였고 다양한 알고리즘의 처리속도를 비교하여 제안하는 Memory Operation System Architecture를 적용한 Stream Processor의 성능 향상을 검증하였다. 실험은 각 알고리즘의 Memory 명령어의 비율에 따라 향상된 성능을 측정하여 Stream Processor의 성능이 최소 8.2%에서 최대 46.5%까지 향상됨을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권5호
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• pp.444-460
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• 2009

In this paper, we propose an expanded patching technique in order to reduce the server network bandwidth requirements to support true VoD services in VoD Systems. Double Patching, which is a typical multicast technique, ensures that a long patching stream delivers not only essential video data for the current client but also extra video data for future clients. Since the extra data may include useless data, it results in server network bandwidth wastage. In order to prevent a server from transmitting useless data, the proposed patching technique uses a new kind of stream called a linking stream. A linking stream is transmitted to clients that have received short patching streams, and it plays a linking role between a patching stream and a regular stream. The linking stream enables a server to avoid transmitting unnecessary data delivered by a long patching stream in Double Patching, so the server never wastes its network bandwidth. Mathematical analysis shows that the proposed technique requires less server network bandwidth to support true VoD services than Double Patching. Moreover, simulation results show that it has better average service latency and client defection rate compared with Double Patching.

• 한국환경복원기술학회지
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• 제20권1호
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• pp.55-75
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• 2017

The purpose of this study is to present the basic data for restoration of physical stream environment by analyzing habitat variables because habitat environment is changed due to the construction of waterfront space in urban streams. Assessment results of 10 habitat variables(three divisions) were almost same as optimal condition, in the reach of reference stream where there are no stream crossing structures and channel alteration. Assessment results of reaches in urban rivers, where streams were improved on water-friendly recreation activities, appeared to be marginal condition. Because habitat environment got worse due to stream improvement works such as construction of weir for water landscape, stepping stones for walking, low water revetment and high water revetment, and high water channel. In addition, in the case of mid gradient stream, the frequency of riffles was small or not existed because the intervals of the river crossing structures was short. In the case of mild stream types, the diversity of the pool was damaged due to the deposition of sludge in the upstream pool of weir and the installation of low water revetment.

• 한국환경복원기술학회지
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• 제9권6호
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• pp.162-167
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• 2006

The urban stream includes the channel and sandbars. The sandbar plays a key role in the riparian ecosystem. For birds and insects the sandbar offers a small strip of habitat and fish and other fauna feed in the boundary of sandbar where eddies occur. So, it is important habitat and source for the flow of energy, matter and organisms through the landscape and act as ecotone between the terrestrial and stream corridors. However, the sandbar changes continuously by the natural process. Thus, it is necessary to measure the shape and area of the sandbar accurately for the efficient urban stream management for the amenity of urban residents and stream protection. The study site is Yangjae Stream where the first natural-style urban stream restoration projected was impelemented by the support of Ministry of Education in Korea. The measurement was taken by the beacon Differential Global Positioning System (DGPS) and the data were stored and analyzed using ArcView Geographic Information System (GIS) program. Therefore, the purpose of this study is to measure the change of sandbars in the urban stream after concentrated stormwater during summer.