• Journal of Wetlands Research
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• v.13 no.2
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• pp.363-375
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• 2011

Recently, Water quiality of urban river largely have gotten better by virtue of sewer pipe laying and sewage treatment plants construction. or the various contaminants which is flowed in into river have generated underwater ecosystem disturbance and red tide by lack of sewage and waste water disposal facilities. With tidal river, taehwa river of ulsan metropolitan city has large river width and gradual stream bed gradient at the dry and storage period. Moreover, the flow is paralyzed due to the bridge pier protection work, consist of the mat foundation which is about 1.2km from two bridge and the contaminant is accumulated. it is caused by of the red tide generated from the several years or it activates. In this study, When flow area is largest by changing independent footing of bridge pier of two bridges and using RMA2 model, we hydraulically analyzed a variable breadth of velocity and discharge. Consequently, flow rate increased the maximum 103%, discharge was exposed to increase the maximum 61%. Directly this cannot extinguish the red tide but suppresses the red tide occurrence or can reduce. And it is determined to prevent the depositioning of the contaminant and can control fundamentally the red tide occurrence cause.

• Journal of Korean Society of Rural Planning
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• v.29 no.4
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• pp.175-182
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• 2023

The purpose of this study, the trend of renewable energy, domestic and foreign renewable energy policies, and the flow of the legal system related to renewable energy location were identified, and a location analysis using public data was studied when solar energy was located. First, renewable energy is leading to energy conversion by reducing the proportion of existing fossil fuel-centered energy sources in the global trend and increasing the proportion of renewable energy, an eco-friendly energy source, and changing the institutional and market structure. Second, large-scale solar energy power plants are installed and operated in rural areas where there is no change in insolation and land prices are cheaper than in urban areas where there are many changes in insolation due to surrounding high-rise buildings and street trees. Third, if a preliminary location review is conducted using public data at this time, it will be easy to identify the optimal location for area and size calculation. Fourth, the solar energy location functional area was studied in area A, and the total area of the target area was 624.5km², with 392.7km² and 62.9% of the avoidance area where solar power cannot be located.

• Journal of Environmental Impact Assessment
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• v.19 no.1
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• pp.91-97
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• 2010

The systematic data management system in the area of river flow analysis has not yet constructed, even though the need is evident due to the complicated process of tremendous input/output data in the modeling study and the importance of visualization of spatial flow variation. The objectives of this study are to suggest the method for analysis of changing river sections affecting ecological habitat characteristics. The effects of ecological habitat characteristics are assessed with respect to changing river sections. A GIS special analysis is created representing in the past section of Nonsan-river using historical data. Topographic surfaces are subject to erosional and depositional forces that a specific set of surface characteristics unique to elevation data. GIS spatial analyst is used to generate surface grids from historical point data. Using the GIS spatial analyst can be constructed sections for anywhere of river. The change of depth between 1979 and 1988, the left bank elevations of a river are increased about 1.5m. But the right bank elevations of a river are decreased about 2.3m caused by erosion. In addition, the change of spatial between 1988 and 2002, the regions of a river from upper stream to midstream are decreased the elevation. But the downstream regions are increased the elevation. These changes are analyzed in GIS program to assess methods for affecting ecological habitat.

• KIEAE Journal
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• v.16 no.1
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• pp.67-71
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• 2016

Purpose: There is a growing interest in rainwater runoff reduction effect of green roof, as flooding caused by increasing impervious surface is becoming more and more frequent in urban areas. This study was conducted to prove runoff reduction and runoff delay effect of the retentive green roof and to investigate its influencing factors to the rainfall events that occurred in the summer of 2013. Method: The experiment intended to monitor the runoff quantity of the retentive green roof($140m^2$) and normal roof($100m^2$) in #35 building in Seoul National University, Seoul, Korea for 75 days in 2013. Result: On analysis of 9 rainfall events, it showed that the retentive green roof has 24.8~100% of runoff reduction ratio, 21.2~100% of peak flow reduction ratio, 0.5~3.75 hours of peak delay, and $1.8{\sim}7.2m^3$ of retaining capacity in an area of $140m^2$. It shows different results depending on rainfall and antecedent dry days. The results show that runoff reduction effect is effective when the rainfall is less than 50 mm and antecedent dry day is longer than five days on average. By installing retentive green roofs on buildings, it can help mitigate urban floods and rehabilitate urban water cycle.

• Wind and Structures
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• v.24 no.1
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• pp.1-24
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• 2017

Wind environment in urban residential areas is an important index to consider when evaluating the living environment. However, due to the complexity of the flow field in residential areas, it is difficult to specify the correct inflow boundary conditions in the large eddy simulation (LES). In this paper, the weighted amplitude wave superposition (WAWS) is adopted to simulate the fluctuating velocity data, which satisfies the desired target wind field. The fluctuating velocity data are given to the inlet boundary of the LES by developing an UDF script, which is implemented into the FLUENT. Then, two numerical models - the empty numerical wind tunnel model and the numerical wind tunnel model with spires and roughness elements are established based on the wind tunnel experiment to verify the present method. Finally, the turbulence generation approach presented in this paper is used to carry out a numerical simulation on the wind environment in an urban residential area in Lisbon. The computational results are compared with the wind tunnel experimental data, showing that the numerical results in the LES have a good agreement with the experimental results, and the simulated flow field with the inlet fluctuations can generate a reasonable turbulent wind field. It also shows that strong wind velocities and turbulent kinetic energy occur at the passageways, which may affect the comfort of people in the residential neighborhood, and the small wind velocities and vortexes appear at the leeward corners of buildings, which may affect the spreading of the pollutants.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.488-494
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• 2023

In this paper, scenario-based urban flood prediction for the entire Jinju city was performed, and a simulation domain was constructed using G2D as a 2-dimensional urban flood analysis model. The domain configuration is DEM, and the land cover map is used to set the roughness coefficient for each grid. The input data of the model are water level, water depth and flow rate. In the simulation of the built G2D model, virtual rainfall (3 mm/10 min rainfall given to all grids for 5 hours) and virtual flow were applied. And, a GPU acceleration technique was applied to determine whether to run the flood analysis model in the target area. As a result of the simulation, it was confirmed that the high-resolution flood analysis time was significantly shortened and the flood depth for visual flood judgment could be created for each simulation time.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.6
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• pp.40-49
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• 2017

The purpose of the research is to analyze the recent cases of green space planning and planting design in Beijing, one of the cities having the worst particulate matters (PM) pollution. This study comprehensively reviewed Chinese academic literature addressing green space planning to reduce PM pollution. In addition, we conducted field observations and interviews with public officials from Beijing Municipal Bureau of Landscape Design in charge of planning and management of green spaces in Beijing. After the extensive review of literature we derived tree planting principles to mitigate the impact of PM from urban road system, residential area, and industrial district. Using the principles we evaluated the three recent cases of planting design to mitigate PM: Beijing Fuxing Road, Fu Run Residential Area and Beijing Beiqi Multipurpose Vehicle Factory. We conclude that green space planning and trees planting are not effective in mitigating negative impact of PM pollution because of inadequate selection of trees and inconsiderate planting composition. We proposed to replace the tree species with the ones capable of reducing the spread of PM, and reorganize planting compositions that consider the directions and characteristics of urban wind flow. This study suggests desirable types of tree species and planting compositions for road, residential and industrial districts, and we expect that it provides helpful guidelines for making planting design and species selection to mitigate the impact of PM in urban landscape.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.328-331
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• 2005

Cheonggyecheon, covered and Paved with concretes for about more than 50 years, is a losing stream crossing over the downtown of Seoul, Korea. Due to several environmental and economic Problems about the Cheonggyecheon area, the Cheonggyecheon restoration construction has started in 2003. In restoration of Cheonggyecheon, hydraulic barriers are to be installed so as to reduce stream depletion rates for maintaining the stream flow with supplying a certain amount of water. This study evaluates the groundwater-stream interaction by analyzing stream depletion rates of Cheonggyecheon. Results show that significant stream depletion occurs at the up-midstream where the Seoul subway lines are concentrated. Simulation results demonstrate that both horizontal and vertical hydraulic barriers impeding groundwater flow into subway lines are more efficient than a horizontal barrier only for stream depletion rate reduction.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.22-30
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• 2007

Nihonbashi River takes more time to discharge water pollution because it runs low-lying areas and is easy to affect tidal flow from downstream. After rainfall, the water environment of the river has become worse. Even though the river is located in the important metropolitan area in Tokyo, it dose not have any connection with people's lives. We took Nihonbashi River as an example to consider methods for river restoration of improving water quality and river environment in densely inhabited urban areas. Especially, the major issue of river restoration is how smoothly and quickly discharges water pollution which flows into with river flow. The conclusion of this project is the effectiveness of improvement of water environment to construct of rock gates in Nihonbashi River and Kanda River to control inflows from upstream and tidal flows from downstream.

• International Journal of High-Rise Buildings
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• v.11 no.4
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• pp.321-329
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• 2022

High-rise buildings constructed adjacent to low-rise structures experience frequent damage caused by the associated strong wind. This study aimed to implement a standard evaluation of the wind environment and airflow characteristics around high-rise apartment blocks using wind tunnel tests (WTT) and computational fluid dynamics (CFD) simulations. The correlation coefficient between the CFD and wind tunnel results ranged between 0.6-0.8. Correlations below 0.8 were due to differences in the wake flow area range generated behind the target building according to wind direction angle and the effect of the surrounding buildings. In addition, a difference was observed between the average velocity ratio of the wake flow wind measured by the WTT and by the CFD analysis. The wind velocity values of the CFD analysis were therefore compensated, and, consequently, the correlations for most wind angles increased.