• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.2
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• pp.139-149
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• 2012

Flooding caused by torrential rains and landslide causes the deaths of people and property damage as well as traffic congestion and isolation. Driver enters the dangerous area when driver doesn't recognize disaster information on the road and the damage is spread over time. In this paper, we will develop a smart phone application to collect dangerous disaster area information and a system based on C/S to manage the data received from the smart phone application. This system can analyze dangerous disaster areas using the data received from the smart phone application and the spatial database analyzed dangerous disaster areas is displayed in the smart phone application using a map server. We think that the suggested system provides more efficient information to user.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1373-1382
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• 2014

This paper presents a hydraulic performance graph model in which the flow carrying capacity of a channel system was determined by accounting the interacting backwater effect among channel reaches and incoming lateral flow. The method utilizes hydraulic performance graphs (HPGs), and the method is applied to a natural channel Nakdong River to examine its applicability. This research shows that estimation results using HPG are close to records from the stage station and the results from a widely-accepted model, HEC-RAS. Assuming that a water level gage site is ungaged, water level estimations by HPGs compared with observation show that with a flood event, the HPGs underestimate in the water level ascension phase, but in the recession phase they overestimate results. The accuracy of estimation with HPGs was greatly improved by considering the time difference of flooding between the observation and estimation locations.

• Journal of Digital Convergence
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• v.10 no.9
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• pp.363-368
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• 2012

The Cluster-based routing protocol is consumed the energy consumption efficiently, but there are many isolated nodes while clustering, so these are impeding energy efficiency. Hop-by-hop based routing protocol is suitable large-scaled network or dynamic environment. However, with the periodic flooding signal and rapid energy loss of near sink nodes, the network life time become shorter. In this paper, We propose the hybrid routing protocol that combine the cluster based routing method for energy efficiency of nodes and hop-by-hop method for re-joining the isolated nodes and load balance of nodes in the near cluster using fibonacci sequence. Based on the analysis, it is proved that the hybrid routing protocol provided higher energy efficiency and less the isolated nodes than previous methods.

• Journal of the Korea Computer Graphics Society
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• v.24 no.3
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• pp.21-31
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• 2018

We introduces a system that enables fast and effective visualization of natural disaster data such as typhoons, tsunamis, floods, and flooding to help make informed decisions in disaster situations. Data containing disaster information consists of a few hundred megabytes to many tens and hundreds of gigabytes, which can not be handled by a PC. This system was implemented in the form of a client-server based service to generate and output results from high-performance servers. The server in a built-in, high-performance cluster handles client requests and sends the result of visualization to the client. Clients can receive the results in any form of images, videos, or 3D graphic model by specifying a desired time frame, effectively viewing the results with a user-friendly GUI.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.2
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• pp.137-153
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• 2013

In order to assess the effects of ecosystem and landscape in around spur dikes, this study had carried out monitoring on the changes of ecosystem and morphologic characteristics in around spur dikes that had been settled in bend of Youngcheon River. The study site was a short reach with length 190m, spur dikes were installed in March, 2008. Monitoring of the site had been started in May 2008 and had been completed September 2011. The results are as follow ; 1) Spur dikes that were installed for channel stabilization are performing effectively hydraulic functions at flooding time. 2) Spur dikes that were installed in water colliding front of river bend brought about sediment deposition between those and formed pools around front of those. Therefore, it was verified to create various physical characteristics in the aspect of channel topography and flow consequently. 3) The survey results that was carried out in October 2008 showed to emerge 25 species of plant, 9 species of fish and 17 species of benthic macroinvertebrates, but the survey results in October 2010 showed to emerge 74 species of plant, 12 species of fish and 19 species of benthic macroinvertebrates. In particular, plant species that emerged in 2011 increased about three times more than those in 2008.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.597-610
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• 1997

One-dimensional numerical models using finite difference methods for unsteady sediment transport on alluvial river channel are developed. The Preissmann implicit scheme and the Lax-Wendroff two-step explicit scheme with the Method of Characteristics for water motion and a forward time centered space explicit scheme for sediment motion are developed to simulate the sediment transport rate and the variation of channel bed level. The program correctness of each model is successfully verified using volume conservation tests. The sensitivity studies show that higher peak stage level, steeper channel slope and longer flooding duration produce more channel bed erosion. and median grain size, $D_{50}=0.4mm$ give maximum volume loss in this study. Finally, the numerical models are found to produce reasonable results from the various sensitivity tests which reveal that the numerical models have properly responded to the changes of each model parameter.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.149-153
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• 2009

Physics-based distributed rainfall-runoff models are now commonly used in a variety of hydrologic applications such as to estimate flooding, water pollutant transport, sedimentation yield and so on. Moreover, it is not surprising that GIS has become an integral part of hydrologic research since this technology offers abundant information about spatial heterogeneity for both model parameters and input data that control hydrological processes. This study presents the development of a distributed rainfall-runoff prediction system for the Guem river basin ($9,835km^2$) using an Object-oriented Hydrological Modeling System (OHyMoS). We developed three types of element modules: Slope Runoff Module (SRM), Channel Routing Module (CRM), and Dam Reservoir Module (DRM) and then incorporated them systemically into a catchment modeling system under the OHyMoS. The study basin delineated by the 250m DEM (resampled from SRTM90) was divided into 14 midsize catchments and 80 sub-catchments where correspond to the WAMIS digital map. Each sub-catchment was represented by rectangular slope and channel components; water flows among these components were simulated by both SRM and CRM. In addition, outflows of two multi-purpose dams: Yongdam and Daechung dams were calculated by DRM reflecting decision makers' opinions. Therefore, the Guem river basin rainfall-runoff modeling system can provide not only each sub-catchment outflow but also dam inand outflow at one hour (or less) time step such that users can obtain comprehensive hydrological information readily for the effective and efficient flood control during a flood season.

• Journal of Nutrition and Health
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• v.33 no.3
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• pp.324-331
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• 2000

A deteriorating North Korean economy, coupled with a devastating natural disaster such as flooding and drought in recent years, brought about a severe food shortage and malnutrition problem which caused a migration of its population including young children to neighboring countries. We conducted a nutritional survey on a total of 436 children, aged 4-19 years old, who migrated to the China side of the border from July to September, 1999. The study subjects were interviewed by Korean-Chinese interviewers who were trained for anthropometric measurements and dietary surveys. Heights, weights, and chest circumference of the subjects were 70-90% of the South Korean reference values for the corresponding age and sex. Dietary intakes of the subjects were found to be extremely poor-the average number of food, mostly of plant origin, consumed in a day was 2.8, and the proportion of the subject who reported to take all three meals in a day while residing in North Korea was as low as 36.2%. Ninety five percent of the subjects had at least one clinical symptom related to malnutrition, 68.6% had 2-4 symptoms, and 15.1% had 5 or more symptoms. The results of this study provided an objective data for the first time on the severity of the food crisis and malnutrition problem that afflicted North Korean older children and adolescents as well as children aged 7 or under as previously reported elsewhere. the wasted and stunted children and youths prevailing in North Korea could exert a negative influence on the country's health and economy. More researches are needed in the future to investigate on the impact of malnutrition in North Korean children on the country's social, economic, and cultural state as well as on the health and nutrition situation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1297-1304
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• 2011

SIP(Session Initiation Protocol) has some security vulnerability because it works on the Internet. Therefore, the proxy server can be affected by the flooding attack such as DoS and service interruption. However, traditional schemes to corresponding Denial of Service attacks have some limitation. These schemes have high complexity and cannot protect to the variety of Denial of Service attack. In this paper, we newly define the normal user who makes a normal session observed by verifier module. Our method provides continuous service to the normal users in the various situations of Denial of Service attack as constructing a whitelist using normal user information. Various types of attack/normal traffic are modeled by using OPNET simulator to verify our scheme. The simulation results show that our proposed scheme can prevent DoS attack and achieve a low false rate and fast searching time.

• Journal of Korean Society on Water Environment
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• v.20 no.1
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• pp.86-92
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• 2004

Lab-scale experiments have been carried out to investigate ammonia stripping with a modified spray tower for removing ammonia nitrogen from swine wastewater. The operating conditions such as initial pH, temperature, air flow, hole size of distributor determining the diameter of water drops, and influent solids concentration were closely examined focusing on removal efficiency of ammonia. As a result of the experiment, in order to achieve high rate of ammonia removal by the air stripping system, the air flow rate must be supplied at high rate with sufficiently high initial pH, temperature. The optimum operating condition to meet the residual ammonia concentration of 300 mg/L was the initial pH of 11.0 at $35^{\circ}C$ with the air flow rate of 20 L/min. It also showed that the smaller hole size is, the higher removal rate of ammonia is expected. However, when used a small sized distributor (2 mm), the flooding problem at the upper column occurred due to clogging of the hole. With regard to the influent solids concentration, it was showed that the lower concentration of solids, the higher removal rate of ammonia. The removal of particulate materials in influent led to improve the removal efficiency of ammonia, rather than to control the operating condition including initial pH, temperature, and air flow. The empirical correlation between KLa and operating parameters would be driven as, $K_{La}=(0.0003T-0.0047){\cdot}G^{0.3926}{\cdot}L^{-0.5169}{\cdot}C^{-0. 1849}$. The calculated $K_{La}$ from proposed formula can be used effectively to estimate the optimum reaction time and to calculate the volume of modified spray tower system.