• 상하수도학회지
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• 제20권3호
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• pp.347-355
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• 2006

Anyang Stream including its main branch is the biggest branch stream of Han River in Korea. The geological and geomorphological characteristics were investigated to the affected area of Anyang Stream, in which rainfall characteristic was analyzed. The water quality surveyed that the analysis of water pollution used to biotic index and biological water pollution. The rainfall pattern in this area was like to that of typical Korea, but the rate of trigger and runoff during summer season(June~August) is more higher than mean of Korea. Before 2003, a dried stream is severe status, which was due to abundant runoff, but this status are improved. After 1997, water quality of stream is recovering status such as water pollution of stream steeply decreased. Especially after 2003, this trend is more quickly improved. Although, owing to the increasing of a T-N and SS at upstream wastewater were due to bad collection of industrial factories, livestock's and mans living, the water quality worsted at upstream. Water quality in total section of main stream was severely contaminated that water-quality limit is 5 with polysaprobic by water self-purification. That of main branch was 1~3limits with ${\alpha}$- and ${\beta}$-mesosaprobic in Anyang city area, But water quality in all area about another branch of Anyang stream except Anyang city area was almost under of 3 grades. Though trying of Anyang city for recover movement(completion of 2nd Sewage Treatment Plant and Water supply pipe system) on Anyang stream, water pollution states of upper branch in Anyang stream was not better than its of 2002 because it may be difference of control area on other cities.

• 한국환경복원기술학회지
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• 제14권4호
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• pp.11-23
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• 2011

Mountain streams, which are major components of an entire river network, play an important role as the source of water, sediment, coarse and fine organic matter, and nutrients for lowland rivers. Therefore, dynamics and downstream linkages of each compartment of the mountain stream can be essential for watershed management in catchment scale. The dynamics and downstream linkages are understood as a development of step-pool sequences along a river course. Recently, stream restoration after flooding event often employ the development of step-pool sequences in the world. In this paper, we 1) examined the geomorphic characteristics and the role of step-pool sequences in steep mountain streams by reviewing the results of past studies, and 2) introduced the case studies of stream restoration using step-pool sequences, and finally 3) addressed design methods considering geometry and stability of artificial step-pool sequences for stream restoration. Step-pool sequences play an important role not only as roughness with energy dissipation but also as heterogeneity of stream feature for aquatic habitat. Step-pool sequences, even if they are constructed artificially along a stream, may be effective for small stream restoration considering eco-friendly torrent controls. So far the artificial step-pool sequences were employed for mountainous streams, but those would be applied to urban stream.

• 한국산학기술학회논문지
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• 제12권1호
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• pp.263-267
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• 2011

본 논문은 하드웨어 잡음원 기반으로 하는 발생기에서 출력되는 정보의 랜덤성 특성을 분석하였다. 또한 발생기 출력열에 라플라시안 필터를 적용하여 보안성을 개선하였다. 먼저 하드웨어 잡음 발생기 출력열의 랜덤성 검증기준을 살펴보고, 라플라시안 필터가 적용된 발생기의 출력열 개선 결과를 제시하였다.

• 대한기계학회논문집B
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• 제27권5호
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• pp.569-578
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• 2003

In the present steady the flow characteristics of turbulent steady flows were experimentally investigated in the exit region of join stream. The experimental was carry out to measure the velocity profiles of air in a square duct. For the measurement of velocity profiles, a hot-wire anemometer was used. The experimental results shows that the velocity profiles do not change behind the fully developed flow region , which is defined as dimensionless axial direction x/Dh=50. In addition, the gradient of shear stress distribution became stable as the flow reached progress downstream.

• 한국물환경학회지
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• 제20권6호
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• pp.698-702
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• 2004

At five stations in Gyeongan River, a tributary of Lake Paldang, physicochemical and biological environmental factors of water, particulate matters, and sediments were investigated biweekly from April 11 to December 22 in 2001. The studied area was characterized as a stream-lake system. The system is primarily referred to a place where the environmental factors had considerably changed depending on the amount of precipitation. As a result, the river turned out to be strongly eutrophicated. Also, some characteristics of the water and the particulate matters at midstream such as average concentrations of conductivity, nutrients, and chlorophyll $\alpha$ were higher than the characteristics of up and down-stream. However, the concentrations of organic matters and ratio of clay and silt of the midstream were determined to be higher than up and down-stream sediments. As the result of the factor analysis, 4 major different patterns for environmental factors are found from samples of water, particulate matters, and sediments.

• 한국농공학회지
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• 제42권5호
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• pp.84-93
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• 2000

To provide the basic information for the water improvement and control of water resource in Boryung fresh water reservoir watershed, the characteristics of stream sediments and water quality of the watershed were investigated through 16 times totally, form November in 1998 to March in 2000. The COD values of stream water quality of the Boryung fresh-water reservoir watershed ranged from 0.75 to 6.38. Total -N concentration affected by the livestock wastes and agricultural activity ranged from 0.45 to 21.80mg/L and which was almost over the quality standard of agricultural water(1.0mg/L). Total-P concentration ranged from 0~0.176 mg/L and average value 0.031 mg/L . The contents of heavy metals from 138.4 to 3,457.3mg/kg and total-P were from 210.0 to 468.3 mg/kg. These were very high according to the influence by the livestock waste and sewage water partly.

• 상하수도학회지
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• 제27권2호
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• pp.207-214
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• 2013

To evaluate characteristics of water quality in Jeju, a study was implemented for Han stream and retention ponds. Inflow water quality of retention ponds was heavily dependent on precedent rainfall, and no pesticide was detected due to the little artificial pollution sources. A smooth settling efficiency curve was noticed because heavy particles were already settled down in front of the retention pond. There were weak relationships between retention time and water quality, and this can be attributable to high concentration of pollutants influx at peak inflow. In addition, as Han stream retention pond has a role of groundwater recharge, inflow control based on water quality as well as quantity is needed to maximize pollutant removal at the retention ponds.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2007년도 학술발표회 논문집
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• pp.846-850
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• 2007

In this study debris like branch or trash are washed and flowed from land to stream by rainfall runoff at mountain or urban stream specially rainy season. These kinds of debris are accumulated at hydraulic construct on the way of flow along the stream. The shape or ratio of like these accumulated debris are various according to the location where it is accumulated and the material what it is, so that it is influenced to be varied to flow characteristics. To be simple of accumulated debris shape, it was made experiments though the variation of open ratio and the shape of accumulated debris by lab experiment using straight channel with two piers. From the result, the water level is inverse proportion to open ratio, and the water level more sensitive to the debris‘ width than length at the same area of accumulated debris.

• 태양에너지
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• 제7권2호
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• pp.74-85
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• 1987

Performances of 3 different aerodynamic analytical models, single multiple and double multiple stream tube, for vertical axis Darrieus turbine were analyzed comparatively. From the study it has been found that the models derived from stream tube assumptions can be useful for simple prediction of basic design characteristics of Darrieus turbine. But, for a large tip speed and solidity ratios, the models has shown a certain limit in its applicability according to the formulation scheme applied. The results have shown that for the case having large tip speed and solidity ratios the consideration due to stream conditions, such as trailing vortices or wakes, should be included for accurate prediction of the aerodynamic performances of Darrieus turbine.

• 대한기계학회논문집B
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• 제21권5호
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• pp.628-636
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• 1997

Flow visualization technique incorporating photochromic dye is used to study the flow characteristics of the gravity driven laminar wavy film. The film thickness and wave speed are successfully measured by flow visualization. As the inclination angle increases, the waves have higher peaks and lower substrate thickness. The measured cross stream velocity at the free surface is up to 10% of stream wise velocity, which shows enhanced mixing in the lump of the film. The measured stream wise velocity profiles are close to parabolic profile near the substrate and the peak but show significant velocity defect near the rear side of the wave. The measured wall shear rate distributions show good agreement with the previous workers' numerical results.