• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.628-631
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• 2007

One of the structural measures for the peak flow reduction is infiltration facilities. There are many types in infiltration facilities - infiltration basin, trench, bed, porous pavement, percolated subdrain, dry well. In this study runoff reduction effect of infiltration trench is analyzed by WinSLAMM. Runoff reduction effect is investigated by each design rainfall and temporal pattern of rainfall particularly. The biggest reduction is shown in Yen and Chow's temporal pattern of design rainfall and the smallest reduction is shown in Huff's first quartile pattern. Runoff reduction rate is presented about 6 to 14 percentage, and the larger return period, the smaller runoff reduction rate.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.525-530
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• 1999

A modified SCS TR-20 model that may be applied to a watershed having rice paddies as a land use type, was formulated and applied to a gauaged watershed. The model was applied to the Balan watershed of 26$\textrm{km}^2$ in size for estimation strorm hydrographs . And the simulation results from the model were also compared with thoses from the SCS model. The results showed that paddy fields play an important role to reduce peak runoff. When fractions of paddies are left to fallow conditions or when rice crop is replaced by other, the peak runoff was found to increase up to 10 to 20 percentg . The reduction rates in peak runoff appear to become greater for heavier storms or higher antecedent moisture conditions.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.557-564
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• 2005

The objective of this study is to evaluate a criteria of intercepting capacity and a reduction goal of overflow pollution load in combined sewer system. In the current criteria of intercepting capacity in the domestic sewage facility standard, it is known that three times of peak sewage (Q) in dry period or runoff flow by 2mm/hr is not appropriate since the intercepted flow is estimated by runoff and show different result even in the same watershed. Though a reduction goal of overflow pollution load can be determined from 1) same level of storm-water runoff pollution load in separated storm sewer, 2) less than 5% sewage load in dry weather period, by the domestic sewage facility standard, the simulated results from storm-water model show large differences between two criteria. While it is predicted that sewage pollution load standard three time larger than separated storm sewer standard in high population density and urbanized area, it is shown that separate storm sewer standard larger than sewage pollution load standard in middle population density and developing area. Accordingly, it is proposed that more reasonable intercepting flow and reduction goal of overflows pollution load should be established to minimize discharging pollution load in combined sewer systems. For the purpose, a resonable standard has to be amended by pollution load balance considering the characteristics of a watershed for generation, collection, treatment, and discharging flow.

• Journal of Environmental Science International
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• v.4 no.1
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• pp.91-103
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• 1995

The reaction rate, equilibrium, and flow injection analysis methods were fundamentally evaluated for the determination of aqueous ammonia. The selected indophenol blue method was based on the formation of indophenol blue in which ammonium ion reacted with hypochlorite and phenol in alkaline solution. In the optimized reaction condition, the reaction followed 1st order reaction kinetics and the final product was stable. The absorbance measurements before and after the equilibrium were utilized for the reaction rate and equilibrium methods. The reaction rate methods, based on the relative analytical signals for the possibility of eliminating interferents, were shown to have good linear calibration curves but the detection limit and the calibration sensitivity were poorer than those in the equilibrium method. The detection limits were 32-49 pub and 24 pub for the reaction rate and equilibrium methods, respectively In the flow injection analysis, the absorbance was measured before the equilibrium reached and thus resulted in 30% reduction of calibration sensitivity. However, the detection limit was 11 ppb, indicating that the peak-to-peak noise for the blank was remarkably improved. Compared to the manual methods, the optimized experimental condition in a closed reaction system reduced the blank absorbance and the inclusion of ammonia from the atmosphere was prevented. In addition, highly reproducible mixing of sample and reagents and analytical data extracted from continuous recording showed excellent reproducibility.

• Journal of Wetlands Research
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• v.21 no.3
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• pp.191-198
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• 2019

High impervious surfaces increase the surface runoff during rainfall and reduces the underground infiltration thereby leading to water cycle distortion. The distortion of water cycle causes various urban environmental problems such as urban flooding, drought, water pollutant due to non-point pollution runoff, and water ecosystem damage. Climate change intensified seasonal biases in urban rainfall and affected urban microclimate, thereby increasing the intensity and frequency of urban floods and droughts. Low impact development(LID) technology has been applied to various purposes as a technique to reduce urban environmental problems caused by water by restoring the natural water cycle in the city. This study evaluated the contribution of hydrologic characteristics and water cycle recovery after LID application using long-term monitoring results of various LID technology applied in urban areas. Based on the results, the high retention and infiltration rate of the LID facility was found to contribute significantly to peak flow reduction and runoff delay during rainfall. The average runoff reduction effect was more than 60% at the LID facility. The surface area of the LID facility area ratio(SA/CA) was evaluated as an important factor affecting peak flow reduction and runoff delay effect.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.41-54
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• 1995

A mathematical model for wall-flow monolith ceramic diesel particulate filter was developed in order to describe the processes which take place in the filter during regeneration. The major output of the model comprises ceramic wall temperature and regeneration time(soot reduction). Various numerical tests were performed to demonstrate how the gas oxygen concentration, flow rate and the initial particulate trap loading affect the regeneration time and peak trap temperature. The model is shown to b in reasonable agreement with the published experimental results. This model can be applied to predict the thermal shock failure due to high temperature during combustion regeneration process.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.35 no.4
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• pp.126-133
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• 2017

This study analyzed hydrological changes of stormwater runoff of Seolleung Jeongneung zone according to the application of LID system based on landscape Architectural technology. The results are as follows. First, when flooding occurred in Gwanghwamun in July 27, 2011, the maximum instantaneous rainfall amount was 183 mm/hr recorded at 10:00 on 27th for 10 minutes, and it was confirmed that rainfall intensity more than three times as high as the maximum rainfall of 57.5 mm/hr. Second, it is possible to control peak flow rate in the case of 1,500mm of soil thickness, so that it is possible to improve the vulnerability of flood damage in Seolleung and Jeongneung zone when applying the LID system. Third, in the berm height scenario, peak flow rate control was not controled in all depth level models, but the first stormwater runoff was delayed by 4 hours and 10 minutes compared to the soil thickness scenario. It was interpreted as a relatively important indicator the soil thickness for the initial stromwater runoff reduction and the berm height for the peak runoff. Through this, the systematic adaptation of landscape-friendly ecological factors within the cultural property protection zone could theoretically confirm the effects of flood disaster prevention.

• Wind and Structures
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• v.21 no.2
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• pp.119-158
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• 2015

The characteristics of the coherence functions of X axial, Y axial, and RZ axial (i.e., body axis) wind forces on the Shanghai World Trade Centre - a 492 m super-tall building with section varying along height are studied via a synchronous multi-pressure measurement of the rigid model in wind tunnel simulating of the turbulent, and the corresponding mathematical expressions are proposed there from. The investigations show that the mathematical expressions of coherence functions in across-wind and torsional-wind directions can be constructed by superimposition of a modified exponential decay function and a peak function caused by turbulent flow and vortex shedding respectively, while that in along-wind direction need only be constructed by the former, similar to that of wind speed. Moreover, an inductive analysis method is proposed to summarize the fitted parameters of the wind force coherence functions of every two measurement levels of altitudes. The comparisons of the first three order generalized force spectra show that the proposed mathematical expressions accord with the experimental results well. Later, the influences of coherence functions on wind-induced dynamic responses are analyzed in detail based on the proposed mathematical expressions and the frequency-domain method of random vibration theory.

• Journal of Korea Water Resources Association
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• v.45 no.1
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• pp.65-73
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• 2012

Recently climate change and increase of surface runoff caused the urban flooding. Traditional way of dealing with urban flooding has been to increase the sewer capacity or construction of pumping stations, however, it is practically almost impossible because of time, money and traffic problems. Multipurpose DRMS (Decentralized Rainwater Management System) is a new paradigm proposed and recommended by NEMA (National Emergency Management Agency) for both flood control and water conservation. Suwon City has already enacted the ordinance on sound water cycle management by DRMS. In this study, a flood prone area in Suwon is selected and analysis of DRMS has been made using XP-SWMM for different scenarios of RT installation with same total rainwater tank volume and location. Installing one rainwater tank of 3,000$m^3$ can reduce the peak flow rate by 15.5%. Installing six rainwater tanks of 500$m^3$ volume in the area can reduce the peak flow rate by 28%. Three tanks which is concentrated in the middle region can reduce peak rate more than evenly distributed tanks. The method and results found from this study can be used for the design and performance prediction of DRMS at a flood prone area by supplementing the existing sewer system without increase of the sewer capacity.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.213-216
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• 2006

This paper was a study about noise reduction through flow stabilization in duct using experimental method and numerical analysis at the same time. To determine the fan's type three kinds of fans(axial fan, centrifugal fan, and axial fan with centrifugal type blades) was examined to investigate the suitability for in-line duct. As a result, under the equal number of rotation 2000 RPM, performance of an axial fan with centrifugal type blades was the most superior by 55dBA at 4.3CMM among other fans. After this, analyzed the results of the numerical analysis to find out the optimum design of pitch angle such as $0^{\circ}$, $10^{\circ}$, $15^{\circ}$ and $20^{\circ}$. The intensity of turbulence was low when pitch angle was $15^{\circ}$ and air volume became peak by 5.08 CMM. It was observed that axis component of velocity increased gradually when pitch angle increased from $0^{\circ}$ to $20^{\circ}$, and embodied noise reduction and improvement of air flow rate through flow stabilization.