• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.3
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• pp.58-68
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• 1988

Most of the Korean watersheds are mountaineous and consist of various soil types and land uses And seldom watersheds are found to have long term hydrologic records. The SNUA, a hydrologic watershed model was developed to meet the unique characteristics of Korean watershed and simulate the storm hydrographs from a small mountaineous watershed. Also the applicability of the model was tested by comparing the simulated storm hydrographs and the observed from Dochuk watershed, Gwangjugun, Kyunggido The conclusions obtained in this study could be summarized as follows ; 1. The model includes the simulation of interception, evaporation and infiltration for land surface hydrologic cycle on the single storm basis and the flow routing features for both overland and channel systems. 2. Net rainfall is estimated from the continuous computation of water balance at the surface of interception storage accounting for the rainfall intensities and the evaporation losses at each time step. 3. Excess rainfall is calculated by the abstraction of infiltration loss estimated by the Green and Ainpt Model from the net rainfall. 4. A momentum equation in the form of kinematic wave representation is solved by the finite differential method to obtain the runoff rate at the exit of the watershed. 5. The developed SNUA Model is a type of distributed and event model that considers the spatial distribution of the watershed parameters and simulates the hydrograph on a single storm basis. 6. The results of verification test show that the simulated peak flows agree with the observed in the occurence time but have relative enors in the range of 5.4-40.6% in various flow rates and also show that the simulated total runoff have 6.9-32% of relative errors against the observed. 7. To improve the applicability of the model, it was thought that more studies like the application test to the other watersheds of various types or the addition of the other hydrologk components describing subsurface storages are needed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1312-1318
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• 2006

One of the common services of telematics is the car navigation that finds the shortest path from source to target. Until now, some routing algorithms of the car navigation do not consider the real-time traffic information and use the static shortest path algorithm. In this paper, we prosed the method to predict the traffic flow in the future. This prediction combines two methods. The former is an accumulated speed pattern, which means the analysis results for all past speeds of each road by classfying the same day and the same time inteval. The latter is the Kalman filter. We predicted the traffic flows of each segment by combining the two methods. By experiment, we showed our algorithm gave better precise predicition than only using accumulated speed pattern that is used commonly. The result can be applied to the car navigation to support a dynamic shortest path. In addition, it can give users the travel information to avoid the traffic congestion areas.

• Water for future
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• v.15 no.3
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• pp.37-47
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• 1982

In the past, the design flow of the urban storm drainage systems has been used largely on a basis of empirical and experience, and the rational formula one of empirical method has been widely used for our country, as well as world wide. But the empirical method has insufficient factor because minimal consideration is given to the relationship of the parameters in the equation to the processes being considered, and considerable use of experience and judgment in setting values to the coefficients in the equation is made. The postcomputer era of hydrology has brought an acceleration development of mathematical methods, thus mathematical models are methods which will greatly increase our understanding in hydrology. On this study, a simple mathematical model of urban presented by British Road Research Laboratory is tested on urban watersheds in Ju An Ju Gong Apartment. The basin is located in Kan Seog Dong, Inchon. The model produces a runoff hydrograph by applying rain all to only the directly connected impervious area of the basin. To apply this model the basin is divided into contributing areas or subbasins. With this information the time area for contributing is derived. The rainfall hyetograph to design storm for the basin flow has been obtained by determination of total rainfall and the temporal distribution of that rainfall determined on the basis of Huff's method form historical rainfall data of the basin. The inflows from several subbaisns are successively routed down the network of reaches from the upstream end to the outlet. A simple storage routing technique is used which involves the use of the Manning equation to compute the stage discharge curve for the cross-section in question. To apply the model to a basin, the pattern of impervious areas must be known in detail, as well as the slopes and sizes of all surface and subsurface drains.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1489-1493
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• 2009

The disaster with many casualties every year by floods, and the economic loss will occur in Korea. The establishment and the recovery measures are necessary. In this research, we analyzed the effect for reducing flood by making washland in flood season, where is used as the wetland in non-flood season in Hwapocheon basin of Nakdong River, Korea. We prepared draingage of inner basin for flood in the past because the water elevation of Hwapocheon is lower than the water elevation of the Nakdong River. On the other hand, now a days, drainage capacity of the expansion and change of the height of the embankment have limitations, because of the increase in torrential rains. In this study, HEC-RAS is used for the unsteady flow routing for the effectiveness analysis of flood level mitigation in flood season. This analysis was performed according to the scenarios of washland construction location and its scale.

• Journal of the Korea Convergence Society
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• v.8 no.8
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• pp.51-57
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• 2017

A wireless sensor network is composed of many resource constrained sensor nodes. These networks are attacked by malicious attacks like DDoS and routing attacks. In this paper, we propose the intrusion detection and prevention system using convergence of software-defined networking and security technology in wireless sensor networks. Our proposed scheme detects various intrusions in a central server by accumulating log messages of OpenFlow switch through SDN controller and prevents the intrusions by configuring OpenFlow switch. In order to validate our proposed scheme, we show it can detect and prevent some malicious attacks in wireless sensor networks.

• Journal of Korea Water Resources Association
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• v.35 no.4 s.129
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• pp.411-423
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• 2002

Accurate and real time forecasting of runoff has a high priority in the drainage basins prone to short, high intensity rainfall events causing flash floods. To take into account the resolution of hydrological variables within a drainage basin, use of distributed system models is preferred. The Landsat Thematic Mapper(TM) observations enable detailed information on distribution of land cover and other related factors within a drainage basin and permit the use of distributed system models. This paper describes monitoring technique of rainfall excess by SCS curve number method. The time series maps of rainfall excess were generated for all the storm events to show the spatiotemporal distribution of rainfall excess within study basin. A combination of the time series maps of rainfall excess with a flow routing technique would simulate the flow hydrograph at the drainage basin outlet.

• Water for future
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• v.27 no.4
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• pp.95-104
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• 1994

The sinuosity model has been developed to simulate to developed to simulate the floodwave in meandering channels by solving the extended Saint-Venant equation with the Preissmann scheme. The suggested model is compared with three conventional floodplain routing methods in terms of governing equations, mass conservation error and floodwave analysis. The sinuosity model produces the mass conservation error of 1.5-1.8%, however the separate channel model produces 9.1% and 27.4% for sinuosity of 1.5 and 2.0, respectively. The model has been used to simulate flow in an idealized meandering river with a floodplain. The attenuation ratio and the travel time ratio are found to increase as the floodplain roughness and width increase and as the sinuosity factor decreases. The model is expected to contribute the floodwave analysis in sinuous channel with compound corss sections.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.161-171
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• 1993

The basin instantaneous unit hydrograph was derived by considering the network geometry and hillslope. The network geometry is quantified in a function, termed the width function, that reflects the distribution of runoff with flow distance from the outlet. The model using the derivation of the basin IUH consists of two components: the routing component of the initial distribution through the network by means of a simplified diffusion approximation and the hillslope component by means of a exponential distribution that is the probability density function of the travel time in the hillslope. The application of this method was tested on four observed flood data of Bocheong stream and Wi stream. The results show that the proposed method can be used for the analysis of the basin IUH.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.2
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• pp.167-173
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• 2004

Fouling of heat exchangers is generated by water-borne deposits, commonly known as foulants including particulate matter from the air, migrated corrosion produces; silt, clays, and sand suspended in water; organic contaminants; and boron based deposits in plants. The fouling is known to interfere with normal flow characteristics and reduce thermal efficiencies of heat exchangers. This paper describes the fouling analysis technique developed in this study which can analyze the thermal performance for heat exchangers and estimate the future fouling variations. To develop the fouling analysis technique fur heat exchangers, fouling factor was introduced based on the ASME O&M codes and TEMA standards. For the purpose or verifying the fouling analysis technique, the routing analyses were performed for four heat exchangers in several nuclear power plants; two residual heat removal heat exchangers of the residual heat removal system and two component cooling water heat exchangers of the component cooling water system.

• Journal of the Korean Society of Marine Environment & Safety
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• v.11 no.2 s.23
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• pp.9-17
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• 2005

In the present maritime traffic conditions of Gwangyang harbor, there exists many hazardous factors which may lead to huge accidents including marine oil pollution. To mitigate the danger to vessels in Gwangyang harbor and to secure the safety of maritime environment, we established one way traffic between No.3 Route and No.4 Route, Designed of deep water line on No.3 route, Extended one-way route for Myo-Do Passage etc.