• The Journal of Engineering Geology
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• v.29 no.4
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• pp.439-449
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• 2019

To prevent the drying-out of streams and to make effective use of stream water and groundwater, it is necessary to evaluate the impact of groundwater pumping on nearby streams. To this end, stream depletion due to groundwater pumping should be investigated in terms of various hydraulic characteristics of the aquifer and stream. This study used the Baalousha analytical solution, which accounts for stream-stage variation over time, to analyze stream depletion due to groundwater pumping for cases where the stream level decreases exponentially and recovers after the decrease. For conditions such as an aquifer transmissivity of 10~100 ㎡ d^-1, storage coefficient 0.05~0.3, streambed hydraulic conductance 0.1~1.0 m d^-1, stream-well distance 100~500 m, and stage recession coefficient 0.1~1.0 d^-1, the contribution of stream water (the dimensionless ratio of stream water reduction rate to groundwater pumping rate) was analyzed in cases where stream level change was considered. Considering the effect of stream-stage recession, the contribution of stream water is greatly reduced and is less affected by the stream-depletion factor, which is a function of the stream-to-well distance and hydraulic diffusivity. However, there is no significant difference in stream depletion under constant- and variable-stage recovery after recession. These results indicate that stream level control can distribute the relative impacts on stream water and aquifer storage during groundwater pumping

• Journal of Korea Water Resources Association
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• v.34 no.5
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• pp.543-549
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• 2001

This research estimated stream discharges indirectly by hydraulic channel routing. Only stage data from three stage stations and river cross section data were used to estimate Manning roughness coefficients and to compute stream discharges. When the discharges were estimated a stage-stage set of conditions was used for upstream-downstream boundary conditions. The research used the data from the upper Mississippi River. The hydraulic channel routings were performed by DWOPER (operational dynamic wave model). The global optimization program of SCE-UA was used to improve the roughness coefficient estimation module of the modified Newton-Raphson method in DWOPER. The results from SCE-US were better. For the case study of a flood, most estimated discharges except a few show errors within 10%.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.274-277
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• 2004

KSLV (Korea Space Launch Vehicle)-I telemetry system will be composed of two telemetry streams: a lower stage telemetry stream and an upper stage telemetry stream. In this paper, the authors present design, implementation and test results of the upper stage telemetry interface for KSLV-I. The telemetry system currently is in the stage of the prototype model development, and its engineering model and flight model will be developed in the near future.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.422-425
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• 2004

To understand runoff Phenomena in Jeju island, some streams are monitored automatically about stream stage, and water quality in Jeju Provincial Water Resources Management Office. Rating curves for stream discharge are reviewed. Stream stages respond very quick to some rainfall events, and parameters influencing runoff phenomena such as landuse, soil condition, preconditoned rainfall, and vegetables will be studied. A few thousand to ten thousand ml/day are estimated from 6 permanent streams in Jeju island.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.426-430
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• 2004

In aquifers connected hydraulically, the levels of groundwater respond to stream stages. Analytical solutions by Laplace transform and convolution integral are used to get some response patterns about hydrogeoiogic parameter such as hydraulic conductivity, specific storage in confined aquifer. This method has the advantage to do hydrogeologic parameter estimations only with stream stage changes.

• Journal of Environmental Science International
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• v.11 no.1
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• pp.57-61
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• 2002

To investigate the flow characteristics by the water stage variation between stream-aquifer, the new solution of nonlinear Boussinesq equation was derived and extended using the Boltzmann transformation. The soundness of the analytic solution obtained from this study was examined by the comparison with the linearized analytic solution and the numerical solution by finite difference method. And the movement, velocity, flowrate and volume of flow caused by the stage variation of stream and the existence of regional gradient were estimated. This new analytic solution can express the groundwater movement between stream-aquifer. So, it might be helpful to manage water environment.

• Annual Conference of KIPS
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• 2021.11a
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• pp.878-879
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• 2021

Most state-of-the-art CNNs for action recognition are based on a two-stream architecture: RGB frames stream represents the appearance and the optical flow stream interprets the motion of action. However, the cost of optical flow computation is very high and then it increases action recognition latency. We introduce a design strategy for action recognition inspired by a two-stream network and teacher-student architecture. There are two sub-networks in our neural networks, the optical flow sub-network as a teacher and the RGB frames sub-network as a student. In the training stage, we distill the feature from the teacher as a baseline to train student sub-network. In the test stage, we only use the student so that the latency reduces without computing optical flow. Our experiments show that its advantages over two-stream architecture in both speed and performance.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.4
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• pp.11-22
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• 2019

The objective of this study was to improve the cross-sectional area and height estimation method using stream width. Stream water levels should be calculated together to simulate inundation of agricultural land. However, cross-sectional survey data of small rural rivers are insufficient. The previous study has developed regression equations between the width and the cross-sectional area and between the width and the height of stream cross-section, but can not be applied to a wide range of stream widths. In this study, cross-sectional survey data of 6 streams (Doowol, Chungmi, Jiseok, Gam, Wonpyeong, and Bokha stream) were collected and divided into upstream, midstream and downstream considering the locations of cross-sections. The regression equations were estimated using the complete data. $R^2$ between the stream width and cross-sectional area was 0.96, and $R^2$ between width and height was 0.81. The regression equations were also estimated using divided data for upstream, midstream and downstream considering the locations of cross-sections. The range of $R^2$ between the stream width and cross-sectional area was 0.86 - 0.91, and the range of $R^2$ between width and height was 0.79 ? 0.92. As a result of estimating the cross-sections of 6 rivers using the regression equations, the regression equations considering the locations of cross-sections showed better performance both in the cross-sectional area and height estimation than the regression equations estimated using the complete data. Hydrologic Engineering Center - River Analysis System (HEC-RAS) was used to simulate the flood stage analysis of the estimated and the measured cross-sections for 50-year, 100-year, and 200-year frequency floods. As a result of flood stage analysis, the regression equations considering the locations of cross-sections also showed better performance than the regression equations estimated using the complete data. Future research would be needed to consider the factors affecting the cross-sectional shape such as river slope and average flow velocity. This study can be useful for inundation simulation of agricultural land adjacent to an unmeasured stream.

• The Korean Journal of Ecology
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• v.14 no.2
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• pp.195-210
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• 1991

The primary succession of the pebble area in gye-bang chon, an upper stream bank of north han river, was investigated by belt transect method from July to October 1990. The stsges of bare area, herbaceous pioneer, perenial herb, woody plants and pine stand were recognized from stream bank to inland. The change of the coverage in herbaceous plants increased with developing sueccessional sere but decreaser with increment of woody plants. The species sequence cyrves vs. relative coverage were geometric in pioneer stage and graduaiiy changed to lognormal y\type as the development of forest. The species diversity was highest during then woody plants stage, probably it would to be the edge effect. The soil properties were not noticeable difference between stream side and inland side. It seems that the vegetational developement was not enough to affect soil accumulation.

• KCID journal
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• v.17 no.2
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• pp.71-81
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• 2010

Stream Pilot Project, which began in May 2003 and finished in December 2003, was selected to develop effective methods applicable to nature-like streams. Stream restoration projects aim to maintain or increase ecosystem goods and services while protecting downstream and coastal ecosystems. Fields environmental monitoring such as flow discharge and precipitation were conducted along the Idong stream for amount of channel zone change in 2007. This study selected three monitoring positions to measure the water level and discharge of flowing water. A stage-discharge relation is obtained from direct discharge measurements for three stations by fitting an empirical relationship to the data set. Since discharge measures are made only for low flow conditions, a curve of discharge against stage can then be built by fitting these data with a power curve. And this study used data obtained from floodmark checkup as well as HEC-RAS model to analyze the hydrodynamic characteristics of monitoring sites. Reach-averaged hydraulic parameters for the supply reach were calculated from the small area's HEC-RAS model for Idong stream, and a HEC-RAS model used to analyze hydraulics for a period in 2007, after the stream was considered bank stabilization.