• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.6
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• pp.57-69
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• 1998

The creation of favorable water space, in our living circumferential space, is very important factor to offer rural scenery to neighbor residents. We are to introduce stream landscape arrangement technique considering favorable water environment against conventional methods. In this study, the modeling district is Seungdu small stream of Ansung river system in Pyung-Teak city, Kyonggi province, and we carried out stream landscape simulation. The arranging plans of landscape are classified ti three types. The first one is conservation type of ecological environment that can express natural characteristics of stream inherence, raise variety of living things and construct coexisting environment between human beings and the other living things. The secong one is favorable water approach type. The basic object of this type is space construction for easy approach to waterside and increase of comfortable feelings of spectators. The third one is water utilization/flood control management type. In planning of environmentally favorable landscape arrangement, this type is the most important but is likely to be ignored. This type is an arranging plan of stream landscape considering safety. Also, we developed Streams Landscape Simulation System(SLSS). This program can be used for comparison of original landscape image with simulated one. To apply SLSS on the interested stream, landscape simulation that is based on hydraulic characteristics, runoff, flow direction, detailed conditions of basin and ecosystem of stream have to be executed. In this point, developing a stereographical technique of image processing and exact study of applying plan have to be executed continually.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.4
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• pp.77-91
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• 2011

This study tries to find a streambed scouring and sedimentation characteristics through the Rosgen(1994)'s stream classification system while experiencing several flood events. The Jinwee and Osan streams, the tributaries of Anseongcheon were selected. The streams showed type C or type E. By the classification results, two Type C tributaries one Type C stream and one Type E tributary were selected. For the four selected stream reaches, the analysis of streambed change was implemented by using numerical model CCHE2D (Center for Computational Hydroscience and Engineering). To prepare the inlet boundary conditions of each stream, the WMS (Watershed Modeling System) HEC-1 was used and the streamflows of 50, 80, and 100-year return period were generated and the outlet boundary was set to an open boundary condition. The simulation results showed that when the flood pulse periodically the streambed changes also appears regularly. The results can be used to acquire the basic data for stream restoration.

• Journal of the Korean Geographical Society
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• v.32 no.4
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• pp.421-434
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• 1997

Flume experiments are conducted to describe channel adjustments at stream confluences and to examine some factors to which changes in channel characteristics are subject. There are different factors controlling channel size and shape; shereas the fomer is primarily controlled by water discharge alone, the latter including channel slope is influenced by sediment load as well as water discharge. The morphometric adjustments of confluent tributaries can be consequently classified into three types based upon changes in sediment concentration which are associated with the relative increasing rates of water discharge and sediment load at these sites. Flow is accelerated at stream confluences due to the convergence of confluent flows, causing an sharp increase in velocity. It restrains an increase in channel capacity, and furthers a decrease in channel slope, of a receiving stream. As a result, effects of slight increases in sediment concentration hardly appear on changes in channel characterisitics at stream confluences.

• Journal of ILASS-Korea
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• v.12 no.2
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• pp.115-122
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• 2007

The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomize. internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD (Sauter Mean Diameters) distribution by using Planar Liquid Laser Induced Fluorescence technique. The objectives of this research are get a droplet distributions and drop size measurements of each condition and compare with the other flow effects. As the result, This research has been showned that droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects, and normalized distance from the injector exit length(x/d, y/d). There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.486-491
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• 2008

The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomizer internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD(Sauter Mean Diameters) distribution by using PLLIF(Planar Liquid Laser Induced Fluorescence) technique. The objectives of this research are getting a droplet distribution and drop size measurement of each condition and compare with the other flows effect. As the result, This research have been showed the droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects and normalized distance from the injector exit length.(x/d, y/d)There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.4
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• pp.57-65
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• 1999

A modified gas tracer method was used to obtain reaeration coefficient from an artificial channel and a reach of Bokha stream, Ichon city. Propane was used as the tracer gas and Rhodamine-B dye as a dispersion and dulution tracer. Concentrations of propane in water sample were measured using a gas chromatograph and concentrationsof dye using UV-Spectrophotometer. To compare measured values with predicted values,commonly used 14 equations were selected . Results of this study suggested that the modified gas tracer method is a potentially useful procedure for th edetermination of reaeration cofficients. However, estimated reaeration coefficients from predictive equations were significantly different from that of this study. Therefore, when using predictive equations, careful selection of equation with consideration for hydraulic characteristics such as flow depth and average velocity, or use of newly derived predictive equation which is adequate for questioned stream would be needed.

• Journal of Korea Water Resources Association
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• v.45 no.1
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• pp.1-13
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• 2012

Various input data required for water quality modeling have considerable impacts on modeling results and relevant analysis due to the absence of data standardization and lack of data accuracy. With this in mind, this study mainly focused on the designing Korean Reach File for more effective water quality modeling through the supply of database composed with accurate hydraulic and hydrologic data. The Korean Reach File is the hydraulic database with the locational information of individual reaches, and each reach represents the stream reach of homogeneous hydraulic characteristics. In detail, it has reach code designating each stream reach, and topological information including catalog unit, segment, marker and index. It was also designed considering linkage of existing codes such as stream name and stream code. The devised reach code was implemented to Kyungan River at the City of Gwangju of Kyunggi Province and the results showed that the reach code could effectively support the input database integrating basic numerous data required for water quality modeling based on a criterion as well as easier linkage and utilization with existing database. In addition, more systematic water quality management was enabled through the linkage of existing data such as treatment facilities, pollutant data, and management institutes using the reach codes defined for each stream section. In the future, more efforts need to be made to adopt the reach code as the national standard data thereby enabling utilization of numerous relevant database through the assigning of reach code to individual stream reaches nationwide.

• Water Engineering Research
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• v.1 no.1
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• pp.83-92
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• 2000

Jet flow can occur by gate opening at downstream of a hydraulic structure such as weir of drainage gate. If the stream bed is not hard or the bed protection is not sufficient, vortex erosion occurs and a resulting scour hole will be formed due to the high shear stress of the jet flow. Once the scour hole is formed, a vortex occurs in ti and this vortex causes additional erosion. If this erosion continues and reaches to the hydraulic structure, it can undermine the bottom of the hydraulic structure and this will lead to failure of the structure itself. Thus, it is necessary to define the physical features of the vortex structure in the scour hole for the design of the bed protection. This study presents the turbulent vortex structure in the scour hole by the gate opening of the hydraulic structure. Characteristics of vortex motion, circulation, vortex scale and vortex were analyzed through experiments. Experimental results of the vortex velocity were compared with theoretical ones. From these, circulation and vortex scale were obtained with known values of inflow depth, inflow velocity and scale of scour hole

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.4
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• pp.383-391
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• 2020

In this study, Hunt's analytical solution and Ward & Lough's analytical solution for two-layered leaky aquifer system were used to estimate stream depletions due to shallow and deep groundwater pumping, and their differences were compared. Depending on the combination of the separation distance between the stream and the well, the transmissivity and the storage coefficient of the aquifer, and the leakage coefficient between the upper and lower layers, the stream depletion, which is the amount of stream water reduction compared to the amount of groundwater pumping, for each of 45,000 cases was calculated for both shallow and deep groundwater pumping, and the differences were analyzed quantitatively. When the leakage coefficient was very small, with a value of 10^-61/d, the difference in the average five-year stream depletion due to the pumping of shallow and deep groundwater showed a large deviation of up to 0.9 depending on the given hydraulic characteristics; this value exponentially decreased as the stream depletion factor (SDF) increased. This exponential relationship gradually weakened as the leakage coefficient increased due to interaction effects between layers, resulting in a small difference of up to 0.2 when the leakage coefficient reached 10^-31/d. Under the condition of greater interlayer hydraulic connectivity, there was little influence of the depth of groundwater pumping on the stream water reduction.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.59-63
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• 2006

A direct photograph measurement technique was used to determine the spatial distribution of the spray droplet diameter in subsonic crossflow and it also obtain that SMD distribution by using PLLIF technique. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of this research are getting a droplet distribution and drop size measurement of normal flow and compare with the other flow effects. Although the study showed visually that drop size were spatially dependent of Air-stream velocity, fuel injection velocity, and normalized distance from the injector exit length.(x/d, y/d) There are also difference characteristics between cavitation, hydraulic flip and the normal flow.