• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.163-169
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• 2011

This paper introduces a method about water line detection using SAR image. The method includes pre-processing of the SAR image with the threshold of the histogram to recognize the boundary between the water and the landmass area. Finally we applied the image differentiation to detect the water line in the SAR image. The TerraSAR-X and the Cosmo-SkyMed images, which are the high spatial resolution X-band SAR data, are used for the evaluation of our algorithm. The accuracy is verified over the stream line in urban area with the result from the Cosmo-SkyMed.

• Bulletin of the Korean Chemical Society
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• v.20 no.10
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• pp.1165-1171
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• 1999

The analysis of trace herbicides using the on-line SPE-HPLC system and a photochemical reaction was studied. 18 compounds of herbicides including eight triazines, six phenoxy acids and esters, and four other herbicides were examined. The on-line SPE-HPLC system developed for selection of eluting solvent improved chromatographic efficiency. The recoveries of herbicides were higher than 77%. With 100 mL tap water samples, the detection limits for all analytes were in the 0.1-2.3×10-10 M range. Detection was done by a UV or fluorescence spectrometer after photochemical reaction at the end of the column with 2W or 450W mercury lamp. Without a photochemical reaction, all compounds responded to 230 nm UV detector, but phenoxy acids and esters were weakly detected. However, with a photochemical reaction, these compounds were selectively detected at 320 nm wavelength of UV absorption and 400 nm emission of the fluorescence detectors. This method can be used for the analysis of environmental water containing herbicides at trace levels.

• Korean Journal of Geomatics
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• v.1 no.1
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• pp.75-83
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• 2001

Due to the fast industrial growth and unplanned urban underground development in Korea, systematic management for water lines could not be accomplished. Unsystematic water line management has resulted in difficulty in finding the exact location and the age of the lines, which has the potential of leading to a disastrous situation. The objective of this study is a development of safety management system for water lines using GIS. This system is constructed to easily estimate water line deterioration by the geographic output system on it, search for damaged objectives near the surrounding area in a situation of destruction, and offer the emergency information by which one can quickly take action. Also, it is constructed to prevent accidents from occurring during work by presenting underground utilities and states of work.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.391-392
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• 2007

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.5 no.1
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• pp.14-20
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• 1969

A scale model net test of the operation of a small two-boat midwater trawl net was performed in the circulating water tank at Pusan Fisheries College. The 1/32 scale model net was constructed after the modelling law of M. Tauti. This type of net is used in Europe for catching sprat like Hering. The net used was 1/32 the actual size. This scale was chosen with consideration for the water tank size. In this experiment, the transfomation of the net shape was observed especially inregard to variations in the height and breadth of the net mouth. These dimensions were varied by changing the breadth of the towing line and the connenting spread.

• Ocean and Polar Research
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• v.41 no.1
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• pp.19-34
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• 2019

The present study obtained universal mathematical models of all elements and characteristics regarding hook and line fishing systems. To describe the hook and line fishing systems on site we used three kinds of coordinate systems: the earth based coordinate system, natural coordinate system, and flow (velocity) coordinate system. Mathematical models presented in this article allow us to define the shape of the fishing gear, the tension of the rope at different points, hydrodynamic resistance, diameter of the hook's wire, immersion depth of the fishing hooks, distance from hooks to the ground and the required lifting force of the floats. These models allow for the performance of computer simulations regarding any kinds of hook and line gears in still water or water where flow occurs.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.3
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• pp.61-72
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• 1999

To obtain the experimental data for design and operation of actual filtration processes, a sand filter and three kinds of dual media filters in pilot-plant scale were operated in this study. We analyzed the effect of filter medium composition on the filter performance and the effects of backwash water flow rates, length of stream line and air flow rate on the filter backwash efficiency. We also compared the efficiencies of the combined air-water backwashing and the water backwashing in dual media filters. As the backwash water flow rates or the length of stream line increased, the final turbidity of backwash water was decreased and the filtration duration time after backwash was increased. In the case of the combined air-water backwashing, the backwash water quantity needed for backwashing the dual media filters could be decreased. The total volume of filtered water for the dual media filters during filter run was over three times larger than that for the sand filter. The dual media filters could be operated at a high filtration rate of 360 m/day.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1656-1660
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• 2006

도시 주변의 급격한 택지개발, 도시 인구의 집중, 대규모 계획단지의 개발은 유역의 유출특성에 큰 영향을 주게 되고, 도시화가 진행됨에 따라 불투수 표면이 증가되고 침투율이 감소됨으로써 유출계수의 증가요인이 되고 있다. 이에 따라 유역의 자연 저류지 기능이 저하되고, 우수가 하천으로 유입되는 시간이 단축됨으로써 첨두홍수량 뿐만 아니라 유출총량의 증대를 초래하여 도시 주변의 중소하천 유역에서는 막대한 재산 및 인명 피해가 발생하고 있다. 이러한 도시화로 인해 증가된 유출량을 저감시키는 구조적 방안으로 대부분 강우 유출수를 일시 저류하여 유출량을 조절하는 우수유출 억제시설이 권장되고 있으나, 이들 시설에 대한 수리학적 침수방어능력이 명확히 규명되지 못한 실정이다. 본 연구의 목적은 도시지역 침수방지 대책 수립에 필요한 On/Off-Line 저류지의 평가 및 설계에 기존 부정류 모형들의 모의가능성을 평가 비교하고, 가상하도와 실제하도에 적용하여 모형을 검보정 함으로서 저류지 해석의 실용화 모형을 확립함에 있다. 본 연구 결과는 도시지역에 적용할 수 있는 도시홍수방어시스템의 일환으로 구축함으로써, 도시지역에서 저류지 홍수저감효과를 평가하는 등 침수재해와 연계된 구조적 대책 수립에 필요한 기초자료로 활용하고자 한다. 본 연구에서 연구된 저류지 모형을 이용하여 On-Line 및 Off-Line 저류지에 적용한 결과 두 종류의 저류지 모두 홍수방어를 위해 이용될 수 있었다. On/Off-Line 저류지 모두 첨두유량이 발생할 경우 어느정도의 첨두값의 감쇠를 발생시킬 수 있는 것으로 판단된다. 그러나 저류지 상류단의 수위감소는 저류지로 유출로 인해 저류지 상류 하도부에서 유속의 증가를 발생시켰고 이로 인해 수위는 저류지가 존재하지 않는 경우보다 낮게 나타나고 있다. On-Line 저류지의 경우 Off-Line 의 경우에 비해 수위, 유량이 저류지의 상류단에서 크게 나타났다. On-Line 저류지의 경우 Off-Line 의 경우에 비해 같은 값의 첨두홍수량을 저류하기 위해서 상대적으로 넓은 저류면적이 필요한 것으로 나타난다. 대등한 수위감소값의 홍수저감효과를 발휘하기 위해서 본 연구에서는 On-Line 저류지 면적은 Off-Line 저류지에 비 두배 이상이 필요한 것으로 보여졌다.

• Proceedings of the Korea Water Resources Association Conference
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• 2003.05b
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• pp.627-630
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• 2003

• Water for future
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• v.54 no.7
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• pp.40-45
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• 2021