• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.3
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• pp.229-235
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• 2021

Globally, due to climate change and urbanization, problems with water cycle destruction in urban areas frequently occur. In order to solve this problem, LID technique is being actively conducted the application in urban and research. In this study, some areas of the new city located in Busan was constructed using a widely used SWMM model to verify the effectiveness of the LID technique. This is to present a plan to maximize the efficiency of urban water cycle of the stormwater management target figure and the LID scale calculation method. In addition, the efficiency of runoff reduction using stormwater storage basin was analyzed in urban development projects. By calculating the scale of customized LID for each sub basin, the amount of runoff and peak runoff after LID application was reduced by 86.8 % and 69.5 %, respectively. Depending on the application of the stormwater storage basin, the reduction effect of peak runoff from 0.5 m³/s to 4.9 m³/s and delay effect of 8 minutes to 10 minutes was shown.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.455-463
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• 2011

Conventional construction technologies have been continually applied without consideration of its impact to the environment. This resulted to various problems including the negative responses of local citizens that regarded some constructed facilities as aversive facilities causing environmental and hydraulic problems in the urban area, etc. To prevent these problems, therefore, alternative methods should be undertaken. A new approach termed "Low Impact Development (LID)" technology is currently adapted in developed countries around the world. This study aims to investigate the efficiency of the developed small constructed wetland (SCW) with horizontal subsurface flow as a LID technique applicable in urban areas. Two test-bed facilities were constructed and monitoring had been conducted between July 2010 and June 2011. Based on the findings, the removal efficiencies achieved for TSS, $COD_{Cr}$, TN, TP, Total Fe, Total Pb for the SCW-1 were 66, 53, 46, 55, 67 and 50%, respectively. On the other hand, the SCW-2 attained 82, 62, 51, 48, 74 and 42% efficiency for TSS, $COD_{Cr}$, TN, TP, Total Fe, Total Pb, respectively. The results indicated that the removal of particulate matter and heavy metals which are considered as main pollutants from stormwater runoff in urban areas was satisfactory in the system. Therefore, the test-beds proved to be appropriate for the treatment of pollutants in urban landuses such as road, parking lot, etc. The results of this study can contribute to the conservation of aquatic ecosystems and restoration of natural water cycle in the urban areas.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.789-795
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• 2010

Suspended Solid (SS) is one of the main pollutants and discharges with attached other pollutants such as heavy metal and toxic substance. It is very important to estimate and forecast the release characteristics of SS for water quality improvement. The current studies assumed that SS release rate is proportional to the rain intensity and suggested exponential washoff models. These models related to the shear force of flow. In this study, a new washoff model is suggested based on relation with SS release rate and mean flow rate of the basin surface which is closely related to the shear force. The proposed model is applied to the Goonja drainage district in Seoul, Korea. The new washoff model simulates the SS discharge more accurately in the various rainfall types. The model can be widely applied to the real problems such as the management of non-point source pollutant and the design of treatment facilities.

• Journal of Korea Water Resources Association
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• v.42 no.2
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• pp.105-115
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• 2009

The objectives of this study are to deduce a problem of existing subcatchment width equation in Storm Water Management Model(SWMM) and to analyze the suitability of a new adjusted subcatchment width equation on both ideally assumed watersheds and an actual urban watershed area. The problems of existing subcatchment equation are issued on the theoretical review of the equation and from the model application on different types of simplified assumed watershed. The adjusted equation, proposed in this study, that considers the pipe flows in addition to the surface flows on small subcatchment can improve the limitation of existing equation when applied on the assumed watersheds. Also, Gunja watershed with 96.3 ha is selected and collected rainfall-runoff events for the feasibility study of the proposed equation on actual urban watershed area. The results represent that the simulated flows from adjusted equation rather than the simulated flows from existing equation are well agreed with observed ones.

• Journal of Environmental Science International
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• v.26 no.4
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• pp.493-507
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• 2017

Since the late 20th century, the urbanization in Korea has been rapidly increasing, especially in major cities like Seoul, as a result of industrialization. One of the aspects of urbanization is coating the surfaces with impervious concrete or asphalt that water cannot penetrate. In addition, various urban, such as urban heat islands, which also have a great impact on the urban environment, occur within the cities. Therefore, the urban environment is gradually becoming hot and dry, and the need for more urban parks to compensate for these negative impacts is growing. Thus, several numerical studies have been conducted to assess these problems using coupled Numerical Weather Prediction (NWP) and Computational Fluid Dynamics (CFD). In this study, an experiment was conducted to determine the accuracy of the area of the input field using Weather Research and Forecasting (WRF) model, and applying the more accurate input field to a numerical simulation using ENVI-met, in order to investigate the effect of urban parks on the thermal comfort. The results showed that an input field with a larger area is more accurate than that with a smaller area, because the surrounding terrain and cities are considered in details in the experiment with the larger area. Subsequently, the more accurate input field was used in ENVI-met, and the results of this simulation showed that the presence of the urban park increased the thermal comfort and improved the humidity conditions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.2
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• pp.102-111
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• 1998

Large amount of sludge have been generating in the process of water and wastewater treatment in urban area, and it has been making many environmental problems. Currently almost of sludge is landfilled, and since sludge is difficult to handle and dehydrate, the permeated water from the filled-in ground contaminate the surrounding soil and groundwater which may cause serious environmental and sociological problems. The organic component in sludge can be almost removed through the heat treatment process, and the final product is called artificial soil or artificial media according to the temperature control. To produce artificial media using sludge, chabazite and lime were used as an additive, and the mixture of sludge & additives was thermally treated in the firing kiln at about 800~1, 100。C for about fifteen minutes. The physical and chemical characteristics of the produced artificial media were analyzed, and it showed that it can be used as an artificial media for plant production or soil conditioner for farmland. The concentrations of the toxic heavy metals in the artificial media were lower than the soil quality standard for farmland. The characteristics of produced artificial media, using the mixture of sludge and additives through the heat treatment, is similar to the natural chabazite and soil. The analyzed result of the mineral composition of artificial media showed that it has a characteristics similar to natural stable soil, so the produced artificial media may be applied to farmland or water culture without causing adverse effect. Therefore this study showed that the above process can be a feasible alternative for sludge treatment.

• Advances in aircraft and spacecraft science
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• v.5 no.4
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• pp.499-513
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• 2018

One of the major problems in glass fiber reinforced epoxy (GFRE) composite pipes is the durability under water absorption. This condition is generally recognized to cause degradations in strength and mechanical properties. Therefore, there is a need for an intelligent system for detecting the absorption rate and computing the mass of water absorption (M%) as a function of absorption time (t). The present work represents a new non-destructive evaluation (NDE) technique for detecting the water absorption rate by evaluating the dielectric properties of glass fiber and epoxy resin composite pipes subjected to internal hydrostatic pressure at room temperature. The variation in the dielectric signatures is employed to design an electrical capacitance sensor (ECS) with high sensitivity to detect such defects. ECS consists of twelve electrodes mounted on the outer surface of the pipe. Radius-electrode ratio is defined as the ratio of inner and outer radius of pipe. A finite element (FE) simulation model is developed to measure the capacitance values and node potential distribution of ECS electrodes on the basis of water absorption rate in the pipe material as a function of absorption time. The arrangements for positioning12-electrode sensor parameters such as capacitance, capacitance change and change rate of capacitance are analyzed by ANSYS and MATLAB to plot the mass of water absorption curve against absorption time (t). An analytical model based on a Fickian diffusion model is conducted to predict the saturation level of water absorption ($M_S$) from the obtained mass of water absorption curve. The FE results are in excellent agreement with the analytical results and experimental results available in the literature, thus, validating the accuracy and reliability of the proposed expert system.

• International Journal of Concrete Structures and Materials
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• v.3 no.1
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• pp.15-23
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• 2009

Over about 30% of problems in construction is related to water-leaking, and the loss from this problem can incur as much as three times the cost of initial construction. Thus, water vapor pressure is known to be the primary cause of defective waterproofing. Accordingly, the theories on the relationship between water pressure and temperature as well as damp-proofing volume of concrete and the change in vapor pressure volume were reviewed and analyzed in this study by making test samples after spraying a dampness remover and applying waterproofing materials to the prepared test specimens. The result of measuring water vapor pressure with the surface temperature of the waterproofing (fluid-applied membrane) layer at the experimental temperature setting of about $10^{\circ}C$, which is the annual average temperature of Seoul, indicated that (1) the temperature of the fluid-applied membrane elevated to about $40^{\circ}C$, and the water vapor pressure generated from the fluid-applied membrane was about 0.03 N/mm 2 when the surface temperature of the waterproofing layer was raised to about $80^{\circ}C$. (2) when the temperature of the fluid-applied membrane of the waterproofing layer was raised from $30^{\circ}C$ to $35^{\circ}C$, water vapor pressure of about 0.01 N/mm 2 was generated, and (3) when a thermal source was applied to the fluid-applied membrane (waterproofing) layer, the temperature increased from $35^{\circ}C$ to $40^{\circ}C$, and approximately $0.005\;N/mm^2$ of water vapor pressure was generated.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.5 no.3
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• pp.58-65
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• 2002

This study synthesizes previous research accomplishments with analysis of problems and counterplan for the riparian forest zone management and ongoing research strategy is suggested. If a part of budgets for water use allotments is supported for forest watershed owner, this policy for the forest owner could encourage the forest management of watershed. Integrated riparian forest management guideline in city and county needs to be established for the implementation of government guidelines. Base on the guideline, working plans of city and county could be evaluated. Public Forest Tending Work for stream water quality and quantity conservation should be enlarged for forest watershed and forest area management in five big river watersheds. Forest watershed should be managed with a connected system for a pollutant reduction strategy in urban and industrial areas.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.12 no.1
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• pp.25-34
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• 1994

Water Information Systems requires efficient management, fast and highly advanced data processing. To respond these requirements promptly, it is essential to operate proper information systems. In the future, the system should be extended to comprehensive urban information systems. To implement these tasks, the user needs assessment were done using the study site data, Nonhyun-dong, Kangnam-ku, Seoul. Based on these analyses, the parcel-address based water information system was developed using the Arc Macro Language(AML) in Arc/Info, a vector-based GIS. The system was tested at the study site, then, the technological and institutional problems to be solved were discussed for the successful water information system.