• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.4
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• pp.419-427
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• 2023

This study, analyzed the stomach contents, stable isotope signatures (δ¹³C and δ¹⁵N) in muscle tissue, and potential food sources (particulate organic matter, Zostera marina, epiphytes, and zooplankton) of Sardinops melanostictus in the southern coast of Korea to evaluate its dietary changes across seasons (summer and autumn 2022). The diet of S. melanostictus predominantly comprised organic detritus (99%) regardless of the season. The isotope results showed that S. melanostictus had mean δ¹³C and δ¹⁵N values of -17.7±0.4‰ and 10.6±0.5‰, respectively and seasonal variations were observed (t-test, P=0.010, P=0.002). However, the isotopic mixing model showed that particulate organic matter was a major nutritional source for S. melanostictus in summer and autumn (88.7% and 90.2%, respectively). Based on the stomach contents and stable isotope signatures, these results may help improve the understanding of S. melanostictus and establish the management measures for their conservation.

• Korean Journal of Hydrosciences
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• v.3
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• pp.45-59
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• 1992

The flow characteristics varying with rate of the radius of curvature to width (Rc/B) in open channel bends are investigated with a simplified numerical model. Secondary flow velocity and transverise bed slope are formulated from the equations of momentum and force balance analysis, respectively. The conservation equations of mass and streamwise momentum are simplified by depth integration and its solution could be obtained from the explicit finite difference method. Three sets of computer simulation are executed. The rates of Rc/B adopted in simulations are 2.7, 5.4 and 8.1. The terms analyzed in this paper secondary flow velocity, streamwise velocity, the path of maximum steamwise velocity, deviation angle, and mass-shift velocity.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 1999.12a
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• pp.1-4
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• 1999

This study was performed to develop an information processing system for the sound conservation of soil and groundwater resources. The system contains the geographic information system, and the numerical model of groundwater flow and contamination. Numerical models (MODFLOW,MOC3D) and GIS (ArcView) were integrated for the construction of an integrated management system of subsurface environment. The developed system was applied to the management of three mineral water companies located in clean mountain area. The impact of pumping over the overall catchment basin was modeled using the developed system for the decision of future management criteria.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.328-330
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• 2000

This paper presents an experimental comparison between the conventional generation expansion planning and DSM incorporated one. As a DSM measure, diffusion of high efficient end-uses is considered and its impact will be targeted at the strategic energy conservation. A revised probabilistic production simulation is proposed by modifying the equivalent load duration curve (ELDC) with the capacity deconvolution of DSM end-use. To investigate long-term DSM impacts relative to the conventional planning, WASP model is applied and the effectiveness of DSM planning as an electricity resources is demonstrated.

• Water for future
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• v.24 no.1
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• pp.99-107
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• 1991

This study is for simulating to the model which analyzes flow characteristics and transverse bed slopes in a coarse-streambed of the meandering alluvial channels. Using the equations for conservation of mass, momentum, and for lateral stability of the streambed, a linear differential equation of transverse bed slope is derived from the flow characteristics in curved channels. Its solutions are solved by the Sine-generated curve method(SCM) and compared with results of field measurements. Lag distances by the maximum transverse bed slope and velocity profiles will predict risk sections of concave bank under floods.

• Journal of Korea Water Resources Association
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• v.44 no.2
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• pp.145-156
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• 2011

Two dimensional numerical model of high-order accuracy is developed to analyze complex flow including transition flow, discontinuous flow, and wave propagation to dry bed emerging at natural river flow. The bed slope term of two dimensional shallow water equation consisting of integral conservation law is treated efficiently by applying quasi-steady wave propagation scheme. In order to apply Finite Volume Method using Fractional Step Method, MUSCL scheme is applied based on HLL Riemann solver, which is second-order accurate in time and space. The TVD method is applied to prevent numerical oscillations in the second-order accurate scheme. The developed model is verified by comparing observed data of two dimenstional levee breach experiment and dam breach experiment containing structure at lower section of channel. Also effect of the source term is verified by applying to dam breach experiment considering the adverse slope channel.

• Journal of Korean Society of Rural Planning
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• v.28 no.3
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• pp.49-59
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• 2022

Recently, Korea aimed to increase water use efficiency by implementing integrated management according to the water management unification policy. Considering the enormous use of water resources in the agricultural sector, it is necessary to efficiently conserve water in terms of demand management by intensifying the stakeholders' involvement and awareness campaigns. The existing agricultural water management system in Korea is based on a top-down approach by which the government agencies directly plan budgets and policies to be enforced on and implemented by farmers, with little to no involvement of farmers in the decision-making process. However, this process has hindered the desired water resources management and the water conservation goal at the field level. Moreover, the limited research on water governance operations focusing on agricultural water creates a knowledge gap, particularly in Korea. Thus, it is necessary to investigate water governance cases with successful implementations in agricultural and rural areas to identify the factors applicable to domestic governance in Korea. In addition, a more systematic governance model should be established by identifying the subjectivity of the stakeholders' involvement in agricultural water governance. Therefore, this study proposed a new bottom-up model for agricultural water governance, which aims to raise the problem of autonomous water governance while promoting stakeholders' voluntary participation in agricultural water management and reflecting farmers' involvement in the decision-making process. Moreover, if agricultural water governance is expanded nationwide by reflecting agricultural and water resource policies in the future, it is believed that positive effects can be achieved in increasing utilization efficiency and securing sustantiality through agricultural water saving.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.111-111
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• 2018

본 연구의 목적은 조건부 합성 기법(Conditional Merging, CM) 기법을 활용하여 GPM(Global Precipitation Measurement) 위성 자료를 보정하고, 이를 격자기반 분포형 강우-유출 모형(KIneMatic wave STOrm Runoff Model2, KIMSTORM2)에 적용하여 보정된 자료의 효율성을 검토하는데 있다. 모형의 유출 해석은 남강댐 유역($2,293km^2$)을 대상으로 하였으며, 2016년 10월에 발생한 태풍 차바에 대하여 GPM 자료와 CM 기법을 적용한 GPM 자료를 각각 활용하여 결과를 비교하였다. 이 때, 강우자료의 보정은 유역 내 위치한 21개 지점의 지상강우자료를 활용하였으며, 각각의 위성강우자료에 유출 검보정은 남강댐 유역 내 3개의 수위관측 지점(산청, 창촌, 남강댐)을 대상으로 실시하였다. 유출 결과는 결정계수(Coefficient of determination, $R^2$), 모형 효율성 계수(Nash-Sutcliffe efficiency, NSE) 및 유출용적지수(Volume conservation index, VCI)를 이용하여 산정하였다. 지상강우자료와 CM 기법을 통해 보정한 강우자료는 대기의 많은 영향을 받는 위성자료의 특성을 보정하여 공간유출 및 첨두유출을 합리적으로 재현할 수 있을 것으로 예상된다.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.597-610
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• 1997

One-dimensional numerical models using finite difference methods for unsteady sediment transport on alluvial river channel are developed. The Preissmann implicit scheme and the Lax-Wendroff two-step explicit scheme with the Method of Characteristics for water motion and a forward time centered space explicit scheme for sediment motion are developed to simulate the sediment transport rate and the variation of channel bed level. The program correctness of each model is successfully verified using volume conservation tests. The sensitivity studies show that higher peak stage level, steeper channel slope and longer flooding duration produce more channel bed erosion. and median grain size, $D_{50}=0.4mm$ give maximum volume loss in this study. Finally, the numerical models are found to produce reasonable results from the various sensitivity tests which reveal that the numerical models have properly responded to the changes of each model parameter.

• Geomechanics and Engineering
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• v.10 no.4
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• pp.387-403
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• 2016

In this paper, an integrated model for the wave (current)-induced seabed response is presented. The present model consists of two parts: hydrodynamic model for wave-current interactions and poro-elastic seabed model for pore accumulations. In the wave-current model, based on the fifth-order wave theory, ocean waves were generated by adding a source function into the mass conservation equation. Then, currents were simulated through imposing a steady inlet velocity on one domain and pressure outlet on the other side. In addition, both of the Reynolds-Averaged Navier-Stokers (RANS) Equations and $k-{\varepsilon}$ turbulence model would be applied in the fluid field. Once the wave pressures on the seabed calculated through the wave-current interaction model, it would be applied to be boundary conditions on the seabed model. In the seabed model, the poro-elastic theory would be imposed to simulate the seabed soil response. After comparing with the experimental data, the effect of currents on the seabed response would be examined by emphasize on the residual mechanisms of the pore pressure inside the soil. The build-up of the pore water pressure and the resulted liquefaction phenomenon will be fully investigated. A parametric study will also be conducted to examine the effects of waves and currents as well as soil properties on the pore pressure accumulation.