• 전자공학회논문지A
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• 제33A권2호
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• pp.8-14
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• 1996

Key stream generator consisting of several linear feedback shift registers with a nonlinear combining function have been applied in stream cipher system. Most of the papers until now have been focusing on correlation atack and analysis of key stream generator with nonlinear combining function. Given some part of key stream sequences. We can generate identical output sequences with original key stream sequences if the feedback connection and the maximum order of nonlinear combination function are known.

• 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.

• 한국환경복원기술학회지
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• 제3권1호
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• pp.80-90
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• 2000

This study was carried out to introduce 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. Since the end of 20th century, the native ecology and landscape of Japan remained only a limited areas such as stream side, water side and forest areas. Therefore, recently the works of forest conservation and erosion control of environmental restoration on stream side tended to increased. The strategic prospects of environmental restoration in Japan were summarized as follows : 1. From the ecological point of view, we have to develop a certain method and technology in construction of forest conservation and erosion control to prevent environmental problem from erosion control works. 2. We have to restore not only a continuity of stream side forest from a primitive area to an estuary but also the stream side forest to preserve and restore a stream side vegetation on a primitive watershed areas. 3. We have to improve a method of construction or removal of a structure which were constructed in the stream to restore a water side environment and an interaction system for an integration on a forest land, stream, and erosion control. Additionally, we have to establish an integrated evaluation method and an enforcement system after investigation of influences on natural environment, stream, and forest etc. 4. We have to conduct an integrated research to investigate the ecosystem of stream side, and construct environmentally friendly water park and erosion control park which considered natural environment and its landscape. Additionally, we need to introduce and adopt a natural style stream construction method to restore a water side areas.

• 대한토목학회논문집
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• 제12권4_1호
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• pp.97-106
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• 1992

하천 수로망(水路網)의 수로길이와 본류(本流) 수로길이는 사용된 지형도(地形圖) 축척(縮尺)에 따라 각각 다른 값을 나타내며, 이와 같은 지형도상(地形圖上)의 수로길이는 Fractal로 간주할 수 있다. 수로망(水路網)의 하천길이와 본류(本流) 수로길이를 Horton 법칙을 적용함으로써 유역면적비(Ra)만의 함수로 나타내어, 수로망(水路網)의 하천길이에 관한 Fractal Dimension(D)와 본류(本流) 수로길이에 관한 Fractal Dimension(d)를 길이의 비(比)($R_L$)과 유역면적비(比)($R_a$)의 함수로 각각 유도하였다. 유도된 결과식을 금강수계내(錦江水系內) 산성(山城)유역의 수로망(水路網)에 적용하여 기(旣) 발표된 공식과 비교 검토하였으며, Fractal Dimension은 수로망(水路網)의 경우 지형도(地形圖) 축척(縮尺)이 클수록 2에 가까운 값을 나타낸 반면에, 본류(本流)수로의 경우는 1에 가까운 값을 나타내었다. 본 연구의 결과는 지형도(地形圖) 축척(縮尺)에 따르는 수로망(水路網)구성의 정량적(定量的) 분석에 도움이 되리라 생각된다.

• 환경영향평가
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• 제20권3호
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• pp.281-297
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• 2011

The specie composition, stranding crops and the dominant species of phytoplankton were studied in three streams, Namdae-stream, Yeongok-stream and Sacheon-stream from May 2008 to February 2009. The water qualities of the three streams which run into estuary were also examined using phytoplankton indicators. As the result, the phytoplankton appeared 94 taxa in Namdae-stream, 79 taxa in Yeongok-stream and 73 taxa in Sacheon-stream, diatoms appeared the most in phytoplankton. Genus Navicula and Cymbella in diatoms appeared to be over 10 taxa in each stream, N. cryptocephala, N. cryptotenella and N. gregaria, the pollution tolerance taxa, appeared more frequent in the downstream. Due to the separation of each substrate by the rapid water velocity in the upstream, Achnanthes minutissima, a known periphyton, was dominant in upstream site at Namdae and Yeongok-stream. Some construction areas and sites of downstream of Namdae-stream, Yeongok-stream and Sacheon-stream were shown to be polluted because pollution tolerance taxa, such as Cyclotella meneghiniana, Nitzschia palea and Oscillatoria limnetica, were dominant. The total of 20 taxa phytoplankton indicators were found, composed of 16 taxa of Water pollution algae including Oscillatoria limosa, 2 taxa of Clean water algae Meridion circulare and Staurastrum puntulatum, 1 taxa of Toxic algae Microcystis aeruginosa and 1 taxa of Taste and odor algae Fragilaria construens. Water pollution indicators were appeared frequently in polluted sites of biological water quality(DAIpo, TDI) and of sites containing high trophic state index(TSI). Therefore, using the phytoplankton indicators can assess water quality through relation of biological water quality and trophic state index.

• 대한토목학회논문집
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• 제26권3B호
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• pp.241-251
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• 2006

우리나라의 효율적인 하천유역관리를 위해서는 유역 및 하천과 관련된 지형적 수문학적 특성인자들의 신속하고 정확한 추출이 요구된다. 최근, 원격탐사기법과 GIS기법이 도입으로 이것이 가능하게 되었으며 이 기법들을 이용하여 여러 활용 가능한 자료들을 구축하고 있는 실정이다. 본 연구에서는 북한강유역을 대상으로 GIS기법에 의해 1:5,000 NGIS자료로부터 추출하여 DEM과 하천망을 생성하였다. 이를 이용하여 하천특성인자와 유역특성인자들을 추출함으로써 단위유역별 지형학적 특성을 파악하였다. 또한 대상유역을 상류, 중류, 하류 지점으로 구분하여 지형학적 인자를 추출하고 그 특성을 분석하였으며 선형 및 비선형 회귀곡선을 이용하여 그 인자들 간의 상관관계를 분석함으로써 전체유역 뿐만 아니라 상류, 중류, 하류 유역에 특별히 영향을 끼치는 하천특성인자 및 유역특성인자를 구별해 낼 수 있었다. 그 결과 하천특성인자는 전체유역, 상류, 중류, 하류 유역 모두에 크게 영향을 끼치는 인자임을 알 수 있었고, 유역특성인자 중 전체유역, 상류, 중류, 하류 유역에 공통적으로 영향을 끼치는 인자는 유역면적에 대한 총하천연장과 하천총수 임을 알 수 있었다.

• Journal of Computing Science and Engineering
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• 제5권1호
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• pp.85-110
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• 2011

Achieving situation awareness is especially challenging for real-time data stream applications because they i) operate on continuous unbounded streams of data, and ii) have inherent realtime requirements. In this paper we showed how formal data stream modeling and analysis can be used to better understand stream behavior, evaluate query costs, and improve application performance. We used MEDAL, a formal specification language based on Petri nets, to model the data stream queries and the quality-of-service management mechanisms of RT-STREAM, a prototype system for data stream management. MEDAL's ability to combine query logic and data admission control in one model allows us to design a single comprehensive model of the system. This model can be used to perform a large set of analyses to help improve the application's performance and quality of service.

• 한국환경복원기술학회지
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• 제6권2호
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• pp.11-20
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• 2003

This research was conducted to investigate the influences of the solifluction soil and amount of flow on the stream water quality of the Bukhansan National Park from March to october, 2002. The average pH of stream water was higher than that caused by solifluction soil. The average electrical conductivity of upstream water was about 2.1~2.8 times lower than that of downstream water. Linear regression analysis showed that pH and amount of anion($Cl^-$, ${NO_3}^-$, ${SO_4}^{2-}$) of stream water were very significantly correlated with those at the caused by solifluction soil. Structures for erosion control along both sides of stream channel should be designed in order not to influence upon solifluction soil and stream water quality.

• 한국방재학회 논문집
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• 제4권1호
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• pp.51-56
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• 2004

본 연구는 전형적인 도심소재 중 소하천인 오산천 상류를 중심으로 수질변화 현상을 정확히 파악하기 위하여 24시간에 걸친 연속측정을 통해 수질의 변화를 조사하였고, 이러한 결과를 통하여 효율적인 하천관리 방향을 제시하였다. 오산천 수질의 연속조사의 결과로부터, 본류의 수질개선을 위해서는 다음과 같은 일들이 선행되어야 할 것으로 판단된다. 첫째, 본류 수질개선을 위해서는 유입지류의 효율적인 관리방안이 필요하다. 둘째, 하천 본류의 저질로부터 재용출 되는 오염을 방지하기 위한 대처방안이 필요하다. 본 연구에서는 수질저하를 방지하기 위해 단순한 조사만으로도 중 소하천의 효과적인 관리 방안을 제시했다. 따라서 하천에서의 연속적인 수질 모니터링은 하천수질 개선을 위해 중요하며, 나아가 하천환경에서 일어나는 물질순환 및 물질수지는 건전한 하천조성을 위하여 정확히 평가되어야 한다.

• 한국안전학회지
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• 제27권5호
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• pp.9-15
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• 2012

The ignition characteristics in a confined axisymmetric coflow $CH_4$ jet were investigated numerically with the Fire Dynamics Simulator(FDS). The $CH_4$ fuel stream was diluted with main combustion product gases, such as $O_2$, $N_2$, CO, $CO_2$, and $H_2O$, and the mixed fuel stream was heated up to the sufficient temperature where a supplying fuel stream can be ignited. For the calculation of chemical reaction in the simulation, a 2-step global finite chemistry model was considered. Boundary condition for confined wall was optimized by investigating the effects of wall temperature on the ignition characteristics of fuel stream. In addition, the effects of composition of diluents in the fuel stream and fuel stream temperature on the ignition of fuel steam were investigated. The ignition characteristics of $CH_4$ stream with diluents were very sensitive to the wall temperature, composition of diluents in the fuel stream and fuel stream temperature.