• Smart Structures and Systems
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• v.15 no.6
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• pp.1583-1600
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• 2015

When natural disasters occur, including earthquakes, tsunamis, and debris flows, they are often accompanied by various types of damages such as the collapse of buildings, broken bridges and roads, and the destruction of natural scenery. Natural disaster detection and warning is an important issue which could help to reduce the incidence of serious damage to life and property as well as provide information for search and rescue afterwards. In this study, we propose a novel computer vision technique for debris flow detection which is feature-based that can be used to construct a debris flow event warning system. The landscape is composed of various elements, including trees, rocks, and buildings which are characterized by their features, shapes, positions, and colors. Unlike the traditional methods, our analysis relies on changes in the natural scenery which influence changes to the features. The "background module" and "monitoring module" procedures are designed and used to detect debris flows and construct an event warning system. The multi-criteria decision-making method used to construct an event warring system includes gradient information and the percentage of variation of the features. To prove the feasibility of the proposed method for detecting debris flows, some real cases of debris flows are analyzed. The natural environment is simulated and an event warning system is constructed to warn of debris flows. Debris flows are successfully detected using these two procedures, by analyzing the variation in the detected features and the matched feature. The feasibility of the event warning system is proven using the simulation method. Therefore, the feature based method is found to be useful for detecting debris flows and the event warning system is triggered when debris flows occur.

• Journal of the Korean earth science society
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• v.24 no.8
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• pp.704-710
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• 2003

A study for analysing the characteristics of the 'Tsunami Earthquake' and 'Tsunamigenic Earthquake' has been done in terms of stress drop and tectonic characteristics using previous studies on magnitude, moment, energy, and length of fault. The 'Tsunami Earthquake' seemed to occur mainly on the subduction environment with a very low stress drop of about 10 bars and a thrust dip angle comparing those of the 'Tsunamigenic Earthquake' or other earthquakes. Released energy to moment ratio of the 'Tsunami Earthquake' also seemed to be lower. Earthquakes which generated tsunami in the East Sea seemed to be 'Tsunamigenic Earthquake' with a stress drop of about 30${\sim}$50 bars, and an average energy to moment ratio. Hence, stress drop, energy to moment ratio, and thrust dip angle seem to be indicators of earthquakes that produce tsunamis.

• Journal of Ocean Engineering and Technology
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• v.21 no.6
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• pp.64-71
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• 2007

The hypothetical earthquake located on the fault zone along the western coast of Japan, where sufficient time has elapsed since the last earthquake or an earthquake has not occurred yet, is known to possess significant potential energy. The possibility of earthquake activities occurring here in the future is high. It is expected that the resulting tsunamis will cause great damage to the East Sea coast of Korea and affect parts of the southern coast as well. In this study, tsunami that may be caused by a virtual earthquake that is expected in the hypothetical earthquake, along the western coast of Japan, will be estimated using numerical simulation. From this, the effect of the tsunami originating from the hypothetical earthquake on the southeastern coast of Korea will be evaluated by examining the water level rise due to the maximum water level rise and changing time, for each point along the southeastern coast. It will be possible to use the virtual results obtained like this as important basic materials in future disaster prevention plans and designs, for determining the direction of coastal development, for arranging seashore and harbor structures and to carry out wave resistant design for the southeastern coast of Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.207-219
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• 1993

Tsunamis along the east coast of Korea accompanying the 1983 East Sea central region earthquake is hindcasted with numerical models for tsunami propagation and inundation. Both linear and nonlinear models were used to compute propagation and elevation of tsunami waves on the coastal area of Korea. For the mesh refinement, grid system was divided into two sub-regions in Korean coastal area with final 10m grid resolution at interior area where serious inundation was observed. Calculated tsunami height distribution showed a general agreement with coastal observation. With interior detailed mesh system at mid-east coast region, the inundatin at the port of Imwon were qualitatively well reproduced by inundation and runup model.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.5
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• pp.327-334
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• 2011

Simulation of the trans-oceanic or trans-basin propagation of a tsunami is a computer-intensive task. This study demonstrates an effective and detailed visualization technique to deal with the vast amount of surface-elevation and velocity-field output. This high-definition visualization technique is used to present simulations of the 1960 and 2010 Chilean earthquake tsunamis and the 1983 Central East (Japan) Sea earthquake tsunami. This tsunami-visualization method using high-definition graphic animation is an appropriate tool to show detailed tsunami-propagation behavior over an ocean or coastal sea, as exemplified by the Pacific Ocean and East (Japan) Sea tsunami events.

• Journal of Integrative Natural Science
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• v.14 no.4
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• pp.162-175
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• 2021

Recently, due to global warming, the average temperature of the earth has risen, and the glaciers in the Antarctic and Arctic melt, leading to a rise in sea level, which is accompanied by powerful natural disasters such as strong typhoons and tsunamis around the world. Accordingly, a precipitation in summer in Korea also increased, and changes in the form of precipitation were showed with the increase. Compared to the past, the frequency of localized heavy rain is increasing, and the damage from flooding and flooding is increasing day by day. In this study, based on the precipitation data measured in hours from May to September from 2016 to 2021 according to the change in the precipitation form, according to the nature of the torrential rain investigated the change in the summer precipitation form. In addition, the trend of localized heavy rain from 2016 to 2021 was confirmed by classifying them into two types: localized heavy rains caused by cyclones and weather front, and by typhoons and large-scale cyclones. Through this, the change in precipitation due to the climate crisis should not be viewed as a single phenomenon, it should be reflected and discussed on our life focused on scientific and technological development, and it should be used as a stepping stone for realizing a humanistic.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.4
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• pp.160-167
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• 2021

Seabed deformation due to the fault failure have both a spatial variation and temporal history. When the faulting process initiates at a certain point beneath seabed, the failure spreads out to neighboring points, resulting in temporal changes of deformation. In particular, such a process induces tsunami waves from the vertical motion of seabed. The uprising speed of seabed affects the formation of initial surface profile, eventually altering the arrival time and runup of tsunamis at the coast. In this work, we developed a numerical model that can simulate the generation and propagation of tsunami waves by considering the horizontal and vertical changes of seabed in an active and dynamic manner. For the verification of the model, it was applied to the 2011 Tohoku-oki earthquake in Japan and the results confirmed that the accuracy was improved compared to the existing passive and static model.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.11
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• pp.1471-1476
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• 2021

Flood damage can cause floods or tsunamis, which can result in enormous loss of life and property. In this regard, damage can be reduced by making a quick evacuation decision through flood prediction, and many studies are underway in this field to predict floods using time series data. In this paper, we propose a CNN-based time series prediction model. A CNN-based water level prediction model was implemented using the river level and precipitation, and the performance was confirmed by comparing it with the LSTM and GRU models, which are often used for time series prediction. In addition, by checking the performance difference according to the size of the input data, it was possible to find the points to be supplemented, and it was confirmed that better performance than LSTM and GRU could be obtained. Through this, it is thought that it can be utilized as an initial study for flood prediction.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.26 no.1
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• pp.17-33
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• 2023

Disasters in coastal regions are a constant source of damage due to their uncertainty and complexity, leading to the proposal of green infrastructure as a nature-based solution that incorporates the concept of resilience to address the limitations of traditional grey infrastructure. This study analyzed trends in research related to coastal disasters and green infrastructure by conducting a co-occurrence keyword analysis of 2,183 articles collected from the Web of Science (WoS). The analysis resulted in the classification of the literature into four clusters. Cluster 1 is related to coastal disasters and tsunamis, as well as predictive simulation techniques, and includes keywords such as surge, wave, tide, and modeling. Cluster 2 focuses on the social system damage caused by coastal disasters and theoretical concepts, with keywords such as population, community, and green infrastructure elements like habitat, wetland, salt marsh, coral reef, and mangrove. Cluster 3 deals with coastal disaster-related sea level rise and international issues, and includes keywords such as sea level rise (or change), floodplain, and DEM. Finally, cluster 4 covers coastal erosion and vulnerability, and GIS, with the theme of 'coastal vulnerability and spatial technique'. Keywords related to green infrastructure in cluster 2 have been continuously appearing since 2016, but their focus has been on the function and effect of each element. Based on this analysis, implications for planning and management processes using green infrastructure in response to coastal disasters have been derived. This study can serve as a valuable resource for future research and policy in responding to and managing various disasters in coastal regions.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.6
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• pp.363-368
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• 2017

The tsunami flood the coastal cities and damage the land structures. The study on wave pressure and force on land structures is one of the important factors in designing the stability of inland structures. In this study, two - dimensional wave flume tests on the horizontal wave force and pressure of tsunamis on a simplified box-type structure was conducted. Vertical distribution and wave power of horizontal wave pressure over time were measured by pressure sensors and force transducer. Also, those were measured from the different wave breaking types. The vertical distribution of horizontal wave pressure was uniform at the moment when the horizontal wave force to the structure was maximum under the breaking wave condition. A surf similarity parameter was employed in order to figure out the relationship between the maximum horizontal wave force on the structure as a function of various incident wave conditions. As a result, the non - dimensionalized horizontal wave force tends to decrease exponentially as the surf similarity parameter increases.