• Ecology and Resilient Infrastructure
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• v.4 no.1
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• pp.24-33
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• 2017

This study investigates the flow characteristics and bed changes with discharge using a two-dimensional numerical model, Nays2DH. The water depth at the outer part of curved channel is formed deeper from the narrow part after passing through the curved part. The point bar is developed in the wide section and water depth is shallow in the inside of the curved section. The flow is concentrated in the outer pater of the meandering section, which leads to the deep water. In the downstream section where the straight line formed, the flow is concentrated at the center of the bed. Alternating deep water and shallow places are generated due to the continuous formation of meandering. These characteristics are formed by the influence of strong two-stream flow in meandering stream. The dimensionless tractive force is also large in the region where the flow velocity is concentrated. However, in the narrow and sharp meandering river reaches, the pattern of bed changes and the spatial distribution patterns of flow velocity and dimensionless tractive force are inconsistent in the narrow and sharp meandered reaches due to the strong secondary flow.

• Journal of Wetlands Research
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• v.6 no.3
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• pp.83-93
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• 2004

The purpose of this study was to develop the environmental management strategy of streams based on the quantified evaluation method of the stream environment. The six streams in Jinju city flowing into the Nam-river were selected for the case study. The stream environment evaluation was performed considering the following three independent field surveys. First, the stream naturalnesses considering 20 evaluation elements were investigated for each unit section of the streams having the length of 500m and the width of 100m, and then were evaluated into 5 grades. Second, water qualities of the streams were evaluated into 5 grades based on the results of eight times water quality survey. Third, the landuse patterns in the stream basins were evaluated into 5 grades according to the residential area ratio. Finally, the stream environments were classified into 5 grades by integrating the above three subfactors - stream naturalness, water quality, and residential landuse. According to the evaluation results of stream environments, the three environmental management strategies of streams were suggested. As the results of the case study, Panmun stream and Ghajwa stream were evaluated to the forth grade that need active environmental restoration, and Nabul stream and Yonga stream were evaluated to the second grade that need partial environmental restoration while Youngchun river and Dogsan stream were evaluated to the first grade showing the desirable stream environmental condition. The above environmental evaluation results for each stream will be an important reference for the further stream restoration or management plan.

• Journal of Ecology and Environment
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• v.48 no.1
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• pp.85-95
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• 2024

Background: In Korea, riparian zones and some floodplains have been converted into agricultural fields and urban areas. However, there are essential for maintaining biodiversity, as they are important ecological spaces. There are also very important spaces for humanity, as they perform various ecosystem services in a changing environment including climate change. Due to the importance of rivers, river restoration projects have been promoted for a long time, but their achievement has been insignificant. Development should be pursued by thoroughly evaluating the success of the restoration project. Ecological restoration is to accelerate succession, a process that a disturbed ecosystem recovers itself, with human assistance. Ecological restoration can be a test bed for testing ecological theories in the field. In this respect, ecological restoration should go beyond a 'simple landscaping exercise' and apply ecological models and theories in restoration practice. Results: The cross-section of the restored stream is far from natural rivers due to its steep slope and artificial material. The vegetation profiles of the restored streams did not reflect the flooding regime of the river. The species composition of the vegetation in the restored stream showed a significant difference from that of the reference stream, and was also different from that of an unrestored urban stream. Although species richness was high and the proportion of exotic species was low in the restored stream, the effect was offset by the high proportion of gardening and landscaping plants or obligate terrestrial plants. Conclusions: Based on both the morphological and ecological characteristics of the river, the restoration effect in the restored stream was evaluated to be very low. In order to solve the problems, a systematic adaptive management plan is urgently required. Furthermore, it is necessary to institutionalize the evaluation of restoration effects for the development of river restoration projects in the future.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.2
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• pp.359-370
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• 2004

Before the current western medicine was spreaded out in the world as the main stream, each country had treated diseases with the medicine of their own and the traditional medical books, which are so characteristic, are handed down. Considering the earnest assignment to do in Korean medical of this age and one of the tendencies of medical circles in the world is putting together the current medicine with the traditional medicine, the production and spread of the classification system for the technical books which is contained the characteristic of traditional chinese medicine, the present condition of modern chinese medicine, and the future of it, must be settled without delay. The classification system for oriental medicine section developed in the range of the simple system before the time of flowering, since then the western medicine had grew as the main current in medicine in Korea. But until now the rational and realistic classification system based on the changeable time isn't be established, so setting up one of the classification systems for medicine section, it is classified according to the principle of classification system for medicine section. Hereupon, the result was made after researching the changes of modern classification system for korean and studying on the changes of classification system for oriental medicine section of the Korean decimal classification.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.4
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• pp.310-323
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• 2013

In this paper, the aeroelastic static response of flexible wings with arbitrary cross-section geometry via a coupled CUF-XFLR5 approach is presented. Refined structural one-dimensional (1D) models, with a variable order of expansion for the displacement field, are developed on the basis of the Carrera Unified Formulation (CUF), taking into account cross-sectional deformability. A three-dimensional (3D) Panel Method is employed for the aerodynamic analysis, providing more accuracy with respect to the Vortex Lattice Method (VLM). A straight wing with an airfoil cross-section is modeled as a clamped beam, by means of the finite element method (FEM). Numerical results present the variation of wing aerodynamic parameters, and the equilibrium aeroelastic response is evaluated in terms of displacements and in-plane cross-section deformation. Aeroelastic coupled analyses are based on an iterative procedure, as well as a linear coupling approach for different free stream velocities. A convergent trend of displacements and aerodynamic coefficients is achieved as the structural model accuracy increases. Comparisons with 3D finite element solutions prove that an accurate description of the in-plane cross-section deformation is provided by the proposed 1D CUF model, through a significant reduction in computational cost.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1389-1390
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• 2005

• Journal of Korean Society of Forest Science
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• v.86 no.1
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• pp.69-79
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• 1997

The purpose of this study is to acquire essential data to reduce the amount of woody debris resulted from the debris flow. This research examined topographic characteristics of the channelbed affecting generation, movement and storage of woody debris and woody characteristics related to number, sizes, shapes, decay, storage direction to mountainous stream. 1. The number of woody debris had a tendency to increase in proportion to stream width, but it was hardly affected by longitudinal gradient of stream. Especially, the greater amount of woody debris was stored at wide section of the stream with compound channel, and it was found in deposits of channelbed rather than in the present channel. 2. Total woody debris over 10cm in diameter and over 2m in length was 402 units and storage number was 35.3 units per 100m of stream. Average diameter of breast height and length were 14cm and 4m, respectively. The woody debris appeared shorter in length and greater in diameter at down-stream than up-stream. 3. Since woody debris met sediments and bed-materials of great roughness in moving, the greater amount of woody debris without root was found in up-stream and down-stream, but deformed woody debris was discovered in upper stream. Decay of woody debris was more severe in down-stream and woody debris on rotting process was found down-stream. 4. Storage direction of woody debris was mainly parallel to center line of stream, and rate of parallel and perpendicularity was 276 and 126 units, respectively. But, as woody debris storing to the perpendicular direction was unstable, the traveling debris could easily be stored. Therefore, some counterplan was required to prevent the traveling woody debris. 5. Tree species of woody debris was mainly larch, which occupied about two third of total woody debris(256 units). The woody debris of larch is easy to move due to hitting of channelbed materials or lower channelbed fluctuation because the lower part of larch is weaker than its upper part. Therefore, the section of the tree species planting in the riparian vegetation needs much more carefulness.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.35-41
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• 2012

The Numerical simulation was performed on the flow field around the two-dimensional rectangular bluff body in order to complement the previous experimental results of the bluff body stabilized flames [1]. For both fuel ejection configurations against an oxidizer stream, the flame stability was affected mainly by vortex structure and mixing field near bluff body. FDS(Fire Dynamic Simulator) based on the LES(Large Eddy Simulation) was employed to clarify the isothermal mixing characteristic and wake flow pattern around bluff body. The air used atmosphere and the fuel used methane. The result of counter flow configuration shows that the flow field depends on air velocity but the mixing field is influenced on the fuel velocity. At low fuel velocity the fuel mole fraction is below the flammable limit and hence the mixing is insufficient to react. Therefore, as the result, the flame formed at low fuel velocity is characterized by non-premixed flames. For the flow field of co-flow configuration, flame stability was affected by fuel velocity as well as air velocity. the vortex generated by fuel stream has counter rotating direction against the air stream. Therefore, the momentum ratio between air and fuel stream was important to decide the flame blow out limit, which is result in the characteristic of the partially premixed reacting wake near extinction.

• 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%.

• Journal of Wetlands Research
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• v.13 no.2
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• pp.319-327
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• 2011

A hydraulic coefficient is a factor representing the hydraulic characteristics of the stream or river. For that reason, we survey stream characteristics such as cross section for performing the stream improvement plan and then we calculate hydraulic coefficient based on its surveyed results. This hydraulic coefficient can be used as an important parameter to calculate flood water level in stream, sediment discharge and water quality. However, we cannot calculate the hydraulic characteristics in an ungaged basin. To overcome this problem, we used the SWAT model for calculating the hydraulic coefficient in the ungaged basin.