• Nuclear Engineering and Technology
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• v.44 no.3
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• pp.225-236
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• 2012

The Fukushima-Daiichi accident shook the world, as a well-known plant design, the General Electric BWR Mark I, was heavily damaged in the tsunami, which followed the Great Japanese Earthquake of 11 March 2011. Plant safety functions were lost and, as both AC and DC failed, manoeuvrability of the plants at the site virtually came to a full stop. The traditional system of Emergency Operating Procedures (EOPs) and Severe Accident Management Guidelines (SAMG) failed to protect core and containment, and severe core damage resulted, followed by devastating hydrogen explosions and, finally, considerable radioactive releases. The root cause may not only have been that the design against tsunamis was incorrect, but that the defence against accidents in most power plants is based on traditional assumptions, such as Large Break LOCA as the limiting event, whereas there is no engineered design against severe accidents in most plants. Accidents beyond the licensed design basis have hardly been considered in the various designs, and if they were included, they often were not classified for their safety role, as most system safety classifications considered only design basis accidents. It is, hence, time to again consider the Design Basis Accident, and ask ourselves whether the time has not come to consider engineered safety functions to mitigate core damage accidents. Associated is a proper classification of those systems that do the job. Also associated are safety criteria, which so far are only related to 'public health and safety'; in reality, nuclear accidents cause few casualties, but create immense economical and societal effects-for which there are no criteria to be met. Severe accidents create an environment far surpassing the imagination of those who developed EOPs and SAMG, most of which was developed after Three Mile Island - an accident where all was still in place, except the insight in the event was lost. It requires fundamental changes in our present safety approach and safety thinking and, hence, also in our EOPs and SAMG, in order to prevent future 'Fukushimas'.

• Journal of Ocean Engineering and Technology
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• v.33 no.6
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• pp.597-606
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• 2019

Due to climate change, coastal areas are being flooded with torrential rain, typhoons, and tsunamis. In addition, non-point source pollutants (NPSs) that accumulated on the ground, streets, and buildings during the dry season are washed off by rain and stormwater runoff, which adds to the damage associated with environmental pollution, e.g., pollution that makes its way into the ocean. Recently, low impact development (LID) has been considered as a means of controlling water circulation and NPSs. In the coastal area, permeable blocks have been constructed mainly to reduce the flood damage caused by waves. Some important design factors that must be considered to ensure long-term performance are the permeability coefficient, clogging, and the efficiency of the removal of total suspended solids (TSS), but currently there are no standardized design criteria or testing techniques that are used worldwide. Herein, we analyzed the permeability coefficient and the TSS removal efficiency tendency according to the permeability area ratio with an easily-detachable, permeable block filled with calcinated yellow soils as the filter media. Our lab-scale tests indicated that, when the permeability area ratio was 25%, the reduction of the permeability coefficient after clogged was 11%, which was a significant decrease compared to other cases. Permeability persistence increased when the permeability area ratio increased from 50% to 75%. The TSS removal efficiency decreased as the permeability area ratio increased. Our pilot-scale test indicated that the TSS removal efficiency was more than 80% higher in all cases. We also found that the permeability persistence was excellent as the permeability area ratio increased, and, in actual construction, it is effective to set 5.3% of the total area as permeable area in terms of permeability and economic feasibility.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1269-1276
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• 2016

Recently, natural disasters including earthquakes, tsunamis, floods, and snowstorms, in addition to disasters of human origin such as arson, and acts of terror, have caused numerous injuries and fatalities around the world. During such disasters, victims need to obtain information such as the exact location of the disaster and appropriate evacuation routes in order to relocate to safe areas. In this study, We propose the algorithm for Emergency Rescue Evacuation Support System(ERESS). In case a emergency disaster occurs, ERESS is possible to detect it quickly using through the movement of people. The mobile terminal analyzes behavior and location of indoor pedestrian. And it sends the result to the server. The server determines whether an emergency situation occurred or not based on the received transmission information. When an emergency situation occurs, the server will notify it to the mobile terminal. Then, indoor pedestrian conduct emergency evacuation using mobile terminal.

• 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 Association of Geographic Information Studies
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• v.19 no.3
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• pp.43-60
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• 2016

Coastal cities need disaster planning that accounts for the complex causes of environmental disasters such as high tides or tsunamis generated by typhoons, and of river or lowland flooding caused by heavy rains, etc. The elements of the disaster map were initially defined using a Geographic Information System (GIS) to allow for efficient information management. Complex disaster information elements were thus established in this study to create a disaster map of coastal cities. The range of information required for coastal cities includes the type of disaster, evacuation methods, available sheltering facilities, and learning content. These informational elements are intended to build on spatial information based on data available from the Ministry of Public Safety and Security as well as local governments.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.3
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• pp.135-142
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• 2009

The initial free surface profile and energy of a tsunami are closely related to the wave heights of a tsunami in nearshore and can be determined by using the earthquake parameters. Along the Western coast of Japan, the possibility of a tsunami triggering by undersea earthquakes is very high. Many seismologists have attempted to predict the parameters of earthquakes that could occur in these regions, but it is difficult to accurately predict them. As such, several case studies have been conducted involving behaviors of an unexpected tsunami that occurred in this region. If a relationship between the earthquake parameters and the wave heights of a tsunami is found, it would be easier to examine the effects of the tsunami. In this study, several virtual tsunami events have been simulated, and the wave heights of the tsunami are computed by varying the earthquake parameters to examine the relationship between the earthquake parameters and the tsunami wave heights. Numerical simulations have been conducted in virtual topography.

• Journal of Korea Water Resources Association
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• v.36 no.6
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• pp.937-947
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• 2003

A shoreline, which has no the water depth, moves continuously as waves rise up and recede. Therefore, a special boundary treatment is required to track properly the movements of the shoreline in numerical modeling of the behavior of tsunamis or tides near a coastal zone. In this study, convective terms in nonlinear shallow-water equations are discretized explicitly by using a second-order upwind scheme to describe a moving shoreline more accurately. An oscillatory flow motion in a circular paraboloidal basin has been employed to validate the performance of the developed numerical model. Computed results of instantaneous free surface displacements are compared with those of analytical solutions and existing numerical solutions. The run-up heights in the vicinity of a circular island have also been calculated and obtained numerical results have been shown against available laboratory measurements. A good agreement has been observed.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.2
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• pp.81-90
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• 2017

Recent floodplain data are important for river master plan, storm and flood damage reduction comprehensive plan and pre-disaster impact assessment. Hazard map, base of floodplain data, is being emphasized as important method of non-structural flood prevention and consist of inundation trace map, inundation expected map and hazard information map. Inundation trace map describes distribution of area that damaged from typhoons, heavy rain and tsunamis and includes identified flood level, flood depth and flood time from flooding area. However due to lack of these data by local government, which are foundational and supposed to be well prepared nationwide, having hard time for making inundation trace map or hazard information map. To overcome this problem, time consumption and budget reduction is required through various research. From this study, DEM (Digital Elevation Model) from image material from UAVS (Unmanned Aerial Vehicle System) and numeric geographic map from National Geographic Information Institute are used for calculating flooding damaged area and compared with inundation trace map. As results, inundation trace map DEM based on image material from UAVS had better accuracy than that used DEM based on numeric geographic map. And making hazard map could be easier and more accurate by utilizing image material from UAVS than before.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.4
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• pp.145-152
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• 2008

The initial wave lengths of tsunamis can be several tens to hundreds kilometers. Thus, the importance of the frequency dispersive effects in proportion to variation of the wave length, and should be properly considered in numerical simulation of tsunami propagation for a better accuracy. Recently, a practical dispersion-correction scheme has been developed by adding dispersion-correction terms(Cho et al., 2007). The new model employing the numerical technique has been verified by comparing numerical results with available analytic solutions, however, the new model has not yet been applied on a real topography. In this study, the new model is applied on a real topography and its applicability is examined. To study the applicability of the new model, two historical tsunami events are simulated for Sokcho, Mukho and Pohang harbors, with the tide gage records. Numerical results, the arrival time and the maximum water level at the tidal stations, are compared with observed data at each harbor.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.599-609
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• 2017

Desalination plants have been recently constructed in many parts of the world due to water scarcity caused by population growth, industrialization and climate change. Most seawater desalination plants are designed with a submarine pipeline for intake and discharge. Submarine pipelines are installed directly on the bottom of the water body if the bottom is sandy and flat. Intake is located on a low-energy shoreline with minimal exposure to beach erosion, heavy storms, typhoons, tsunamis, or strong underwater currents. Typically, HDPE (High Density Polyethylene) pipes are used in such a configuration. Submarine pipelines cause many problems when they are not properly designed; HDPE pipelines can be floated or exposed to strong currents and wind or tidal action. This study examines the optimal design method for the trench depth of pipeline, analysis of on-bottom stability and dilution of the concentrate based on the desalination plant conducted at the Pacific coast of Peru, Chilca. As a result of this study, the submarine pipeline should be trenched at least below 1.8 m. The same direction of pipeline with the main wind is a key factor to achieve economic stability. The concentrate should be discharged as much as high position to yield high dilution rate.