• Journal of Korea Water Resources Association
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• v.31 no.6
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• pp.727-739
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• 1998

The main objectives o reservoir optimal operation can be described as follows : maximization of the benefits through optimal allocation of the limited water resources for various purpose; minimization of t도 costs by the flood damage in potential damaging regions and risk of dam failure, etc. through safe drainage of a bulky volume of excessive water by a proper reservoir operation. Reviewing the past research works related to reservoir operation, we can find that the study on the matter of the former has been extensively carried out in last decades rather than the matter of the latter. This study is focused on developing a methodology of optimal reservoir operation for flood control, and a case study is performed on the Chungju multipurpose reservoir in Korea. The final goal of the study is to establish a reservoir optimal operation system which can search optimal policy to compromise two conflicting objectives: downstream flood damage and dam safety-upstream flood damage. In order to reach the final goal of the study, the following items were studied : (1)validation of hydrological data using HYMOS: (2)establishment of a downstream flood routing model coupling a rainfall-runoff model and SOBEK system for 1-D hydrodynamic flood routing; (3)replication of a flood damage estimation model by a neural network; (4)development of an integrated reservoir optimization module for an optimal operation policy.

• Korean Journal of Agricultural Science
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• v.25 no.2
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• pp.260-270
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• 1998

The field tests were performed to suggest the rational method for stability evaluation of soft clay. The behavior of settlement-displacement obtained by field monitoring system was to compare and analyze the results of the observationed method, and to investigate the complex behavior of soft clay with filling height. The results of this study are summarized as follows. 1. The horizontal displacement was suddenly increased when physical properties of soft clay showed maximum values and the part of the turning point. The values of these properties were available to the fundamental data for stability evaluation. The shear deformation appeared that difference of the horizontal displacement was maximum values. 2. Although the stability of embankment by step filling showed the unstable part over the failure standard line, the embankment was confirmed stable. So the evaluation of the stability of embankment is reasonable to use the inclination of curve than failure standard line. 3. The horizontal displacement and relative settlement were increased as same ratio at improvement ground. Estimation of shear deformation using Terzaghi's modified bearing capacity should consider the relations of embankment load and undrained shear strength at nonimprovement ground, and minimum safety factor is recommended to use larger than 1.2. 4. Excess pore water pressure was increased with increasing of filling height and decreased with maintain the filling height. The embankment was unstable when filling height was exceed the evaluation standard line, and the behavior of excess pore water pressure and horizontal displacement could use as a standard of judgement of the filling velocity control because their behavior were agree with each other.

• Nuclear Engineering and Technology
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• v.27 no.3
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• pp.393-402
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• 1995

The structural analysis of the reactor coolant system mainly consist of too fields. The one is the static analysis considering the impact of pressure and temperature built up during normal operation. The other is the dynamic analysis to estimate the impact of postulated events such as the seismic loads or postulated branch line pipe breaks event. Since the most important goal of the RCS structural analysis is to prove the safety of the RCS during normal operation or postulated events, a widely proven theory having enough conservatism is adopted. The load occurring on the RCS during normal operation is considered as the basic design loading condition throughout whole plant life time. The most typical characteristic of the RCS during normal operation is the thermal expansion of the RCS caused by reactor coolant with high temperature and pressure. Therefore, the exact estimation on the thermal movement of the RCS is needed to get more clear understanding on the thermal movement behavior of the RCS. In this study, the general structural analysis concept and modeling method to evaluate the thermal movement of the RCS under the normal plant operation condition are presented. To discuss the validation of the suggested analysis, analysis results are compared with the measured data which ore referred from the standardized 1000 MWe PWR plant under construction.

• Journal of Korean Society of Forest Science
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• v.99 no.3
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• pp.259-266
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• 2010

Forest fire occurrence in Korea is highly related to human activities and its spatial distribution shows a strong spatial dependency with cluster pattern. In this study, we analyzed spatial distribution pattern of forest fire with point pattern analysis considering spatial dependency. Distributional pattern was derived from Ripley's K-function according to causes and distances. Spatially clustered intensity was found out using Kernel intensity estimation. As a result, forest fires in Korea show clustered pattern, although the degrees of clustering for each cause are different. Furthermore, spatial clustering pattern can be classified into two groups in terms of degrees of clustering and distance. The first group shows the national-wide cluster pattern related to the human activity near forests, such as human-induced accidental fire in mountain and field incineration. Another group shows localized cluster pattern which is clustered within a short distance. It is associated with the smoker fire, arson, accidental by children. The range of localized clustering was 30 km. Beyond of this range, the patterns of forest fire became random distribution gradually. Kernel intensity analysis showed that the latter group, which have localized cluster pattern, was occurred in near Seoul with high densed population.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.6
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• pp.50-59
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• 2015

This study aimed at suggesting Willingness To Pay (WTP) for introduction of the Traffic Accident emergency Call (TAC) system by using Contingent Valuation Method (CVM) which is a general valuation method. As the method, this study suggested a WTP estimation method of the TAC system with the double-bound dichotomous choice model. In previous studies, the data are processed differently according to the type of questions and analysis models used for the calculation of willingness to pay. Therefore, we re-organized the model by the cases using the truncated data sets, and showed the difference in WTPs. The dataset was developed by more than 500 questionnaire obtained from online and offline survey with the consideration of composition ratio by age group referring housing census in 2010 to mitigate regional bias of samples. At last, this study applied various statistical methods, survival analysis, multiple regression, and Tobit model for better interpretation of the questionnaires.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.2
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• pp.9-19
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• 2002

Steel piers and concrete-filled steel(CFS) piers, in spite of reasonable strength, high ductility, small section, and fast construction, have not been considered as one of alternatives to RC piers even in the highly populated urban area where aseismic safety, limited space and fast construction are indispensably required. This paper, the first of two companion papers for the seismic performance of steel and CFS piers, tests steel and CFS piers under quasi-static cyclic loading to estimate their ductility and strength. Additional details such as rebars and base ribs are added to increase the ductility of a concrete-filled steel pier with minimum additional cost. Also, simplified numerical analyses using nonlinear spring and shell elements are examined for the estimation of the ductility and strength of concrete-filled steel piers and a steel pier. The result shows that concrete-filled steel peirs have higher energy absorption, i.e., ductility and strength than those of steel pier and increasing bonding between in-filled concrete and lower diaphragm, and the improved details of stress concentrated region would be important for the ductility and strength of a pier. Numerical results show that simplified modeling with nonlinear springs and shells has potential to be effective modeling technique to estimate the seismic performance of a concrete-filled steel pier.

• Journal of the Korean Geotechnical Society
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• v.32 no.11
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• pp.83-96
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• 2016

The surface settlement of the back ground of a braced wall due to the ground excavation has the great influence on the safety of the surrounding area. But it is not easy to predict the settlement of the surrounding area due to proud excavation. Estimation of the settlement of the surface ground induced by the deformation of the braced wall is performed by FEM and empirical method (Peck, Clough etc). In this research, surface settlement of the back ground braced wall depending on the joint dips in rocks during excavating the composit ground was measured at the large scale model test (standard: $0.3m{\times}0.3m{\times}0.5m$). The scale of model test was 1/14.5 and the ground was excavated in ten steps. Earth pressure on the braced wall and ground surface settlement on the back ground of a braced wall were investigated. The surface settlement during the excavation depended on the joint dips in rocks on of the ratio of rock layer. Maximum earth pressure and maximum surface settlement were masured at the same excavation step. In accordance with the increase of the rock layer dips and rock layer ratio, the ground surface settlement increased. The maximum ground surface settlement was 17 times larger at 60 degree joint dips in rocks than that of the horizontal ground conditions. And the position of the maximum surface settlement by empirical method was calculated at the point, which was 17%~33% of excavation depth. In accordance with the increase of the rock layer dips and rock layer ratio, the ground maximum surface settlement increased. The ground surface settlement of composite ground is smaller than that of the empirical.

• International Journal of Railway
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• v.1 no.4
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• pp.149-156
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• 2008

During maintenance or construction works in or at the tracks of railways, high risks for passengers and railway staff, especially for the workers on the construction site exist. The high risks result out of the movement of rail vehicles, like trains or construction vehicles, which must be faced by using any available technical and operational technologies for securing them against the environment. Therefore, it is necessary to evaluate the level of protection continuously and to identify new and innovative methods and technologies for the protection of the gang (construction worker, machines and material). Especially on construction sites at line sections with two or more parallel tracks but also with single tracks, there are still a lot of incidents and accidents mostly with seriously injured persons or fatalities. These were mainly gang members that breach the railway-loading gage. By using proper warning or protection systems, the avoidance of such accidents must be achieved. The latest developments. in gang protection systems concern on the one hand fixed barriers in the middle between the construction site and the operated track and on the other hand construction vehicles equipped with automatic warning systems. The disadvantage of such protection methods is that the gang can be warned against an approaching train but a monitoring of the gang members cannot be performed. Only one part of a potential dangerous situation will be detected. If the gang members will overhear the acoustic warning signal of the security staff and the workers will not leave the danger zone in the track, the driver of the approaching train had no chance to react to the dangerous situation. An accident is often inevitable. While the detection of acoustic warning signals by the gang members working on a construction site is very difficult, the acoustical planning of an automatic warning system has to be designed for an acoustic short range level of one meter besides the construction vehicle. The decision about the use of today's technical warning system (fixed systems, automatic warning systems, etc.) must be geared to the technical feasibility and the level of safety which is needed. Criteria for decision guidance to block a track should be developed by danger estimation and economical variables. To realize the actual jurisdiction and to minimize the hazards of railway operations by the use of construction vehicles near the tracks further developments are needed. This means, that the warning systems have to be enhanced to systems for protection, which monitor the realization of the warning signal as a precondition for giving a movement authority to a train. This method can protect against accidents caused by predictable wrongdoing. The actual state of the art technique of using a collective warning combined with additional security staff is no longer acceptable. Therefore, the Institute of Transportation System of the German Aerospace Center in Braunschweig (Germany) will develop a gang warning and protection system based upon imaging methods, with optical sensors such as video in visible and invisible ranges, radar, laser, and other. The advantage of such a system based on the possibility to monitor both the gang itself and the railway-loading gauge either of the parallel track or of the same track still in use. By monitoring both situations, the system will be able to generate a warning message for the approaching train, that there are obstacles in the track, so that the train can be stopped to prevent an accident. And also the gang workers will be warned, while they breach their area.

• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.365-372
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• 2017

Squat exercise is one of the important free weight exercises that can safely and effectively expect the athletic performance by establishing the rationale. Therefore, it is necessary to study the side effects caused by incorrect exercise, scientific countermeasures and to develop a exercise estimation model. It is effective and accurate to use a variety of assistive devices to calibrate athletic posture. The issues of the structural analysis for designing a foot plate for squat exercise is to model the behavior by the dynamic behavior. It should be consider that the center of gravity of each segmented body is different when the maximum load is applied. It is applied to complete system design through simulation method with kinematic dynamic, ground reaction force and load analysis for the free weight exercise equipment, VR device, and safety foot plate. In this paper, the authors propose the design method for the vertical load distribution applied in the design of the foot plate used for the squat exercise mechanism, and based on these results, design make the more safe and reliable free weight exercise equipment system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.120-130
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• 2012

As long span and complex bridges are constructed often recently, safety estimation became a big issue. Various types of measuring instruments are installed in case of long span bridge. New wireless technologies for long span bridges such as sending information through a gateway at the field or sending it through cables by signal processing the sensing data are applied these days. However, The case of occurred accidents related to bridge in the world have been reported that serious accidents occur due to lack of real-time proactive, intelligent action based on recognition accidents. To solve this problem in this study, the idea of "communication among things", which is the basic method of RFID/USN technology, is applied to the bridge monitoring system. A sensor node module for USN based intelligent bridge system in which sensor are utilized on the bridge and communicates interactively to prevent accidents when it captures the alert signals and urgent events, sends RF wireless signal to the nearest traffic signal to block the traffic and prevent massive accidents, is designed and tested by performing TinyOS based middleware design and sensor test free Space trans-receiving distance.