• Journal of Environmental Science International
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• v.27 no.1
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• pp.11-25
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• 2018

Both the propagation velocity and the direction of atmospheric waves are important factors for analyzing and forecasting meteo-tsunami. In this study, a total of 14 events of meteo-tsunami over 11 years (2006-2016) are selected through analyzing sea-level data observed from tidal stations along the west coast of the Korean peninsula. The propagation velocity and direction are calculated by tracing the atmospheric disturbance of each meteo-tsunami event predicted by the WRF model. Then, the Froude number is calculated using the propagation velocity of atmospheric waves and oceanic long waves from bathymetry data. To derive the critical condition for the occurrence of meteo-tsunami, supervised learning using a logistic regression algorithm is conducted. It is concluded that the threshold distance of meteo-tsunami occurrence, from a propagation direction, can be calculated by the amplitude of air-pressure tendency and the resonance factor, which are found using the Froude number. According to the critical condition, the distance increases logarithmically with the ratio of the amplitude of air-pressure tendency and the square of the resonance factor, and meteo-tsunami do not occur when the ratio is less than 5.11 hPa/10 min.

• Geophysics and Geophysical Exploration
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• v.13 no.3
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• pp.295-300
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• 2010

Recently, many tsunamis triggered by impulsive undersea ground motions occurred in subduction zones around the Pacific Ocean area including the East Sea surrounded by Korea, Japan and Russia. The wave height of a tsunami may be in the order of several meters, while the wavelength can be up to 1,000 km in the ocean, where the average water depth is about 4 km. A tsunami could cause a severe coastal flooding and property damage not only at neighboring countries but also at distant countries. A fundamental and economic way to mitigate unusual tsunami attacks is to construct tsunami hazard maps along coastal areas vulnerable to tsunami flooding. These maps should be developed based on the historical tsunami events and projected scenarios. The map could be used to make evacuation plans in the event of a real tsunami assault.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.853-864
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• 2016

Meteo-tsunamis are tsunamis that are typically caused by strong atmospheric instability (e.g., pressure jumps) in low pressure systems, but some meteo-tsunamis in winter can be caused by local atmospheric instability in high pressure systems (e.g., the Siberian High). In this study, we investigated a meteo-tsunami event related to a high pressure system that occurred during winter on the Yellow Sea in 2005. Sea level data from tidal stations were analyed with a high-pass filter, and we also performed synoptic weather analyses by using various synoptic weather data (e.g., surface weather charts) collected during the winter season(DJF) of 2005. A numerical weather model (WRF) was used to analyze the atmospheric instability on the day of the selected event (21 Dec. 2005). On the basis of the results, we suggest that the meteo-tsunami triggered by the high pressure system occurred because of dynamic atmospheric instability induced by the expansion and contraction of the Siberian High.

• Nuclear Engineering and Technology
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• v.50 no.8
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• pp.1234-1245
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• 2018

The risk of multi-unit nuclear power plants (NPPs) at a site has received considerable critical attention recently. However, current probabilistic safety assessment (PSA) procedures and computer code do not support multi-unit PSA because the traditional PSA structure is mostly used for the quantification of single-unit NPP risk. In this study, the main purpose is to develop a multi-unit Level 2 PSA method and apply it to full-power operating six-unit OPR1000. Multi-unit Level 2 PSA method consists of three steps: (1) development of single-unit Level 2 PSA; (2) extracting the mapping data from plant damage state to source term category; and (3) combining multi-unit Level 1 PSA results and mapping fractions. By applying developed multi-unit Level 2 PSA method into six-unit OPR1000, site containment failure probabilities in case of loss of ultimate heat sink, loss of off-site power, tsunami, and seismic event were quantified.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.2 s.21
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• pp.61-68
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• 2006

The earthquake parameters are known to be responsible for determination of the initial free surface profiles of tsunamis. This study investigates the effects of earthquake parameters to variation of initial free surface profiles of tsunamis triggered by an impulsive undersea earthquake. The target event is the 1983 Central East Sea Tsunami recorded as the most devastating tsunami in Korea during last several decades. Among the earthquake parameters, the strike angle may play a most significant role in determining the initial free surface.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.1
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• pp.109-116
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• 1994

Tsunamis generated by of the 1992 Flores Island Earthquake in Indonesia caused tremendous casualties and damages. This tsunami event was hindcasted via numerical tsunami models. Initial conditions were taken from fault parameters from Havard CMT (Centroid Moment Tensor) solution and additional subaqueous slump consideration at the Inner Hading Bay and Riang Krok, Leworahang coasts. The computed results showed general agreements with observations made by the International Tsunami Survey Group. Subsequently a runup model was developed to investigate catastrophic runup at southern shore of the Babi Island with fine grid resolution of 50 m. Computed results were recorded to construct rendered images for video animation. The computer-graphic aided video animation showed a remarkable reproduction of tsunami propagation and runup at southern coast of the Babi Island.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.36 no.2
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• pp.80-86
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• 2024

Large-scale earthquakes are occurring globally, especially in the South Asian crust, which is experiencing a state of tension in the aftermath of the 2011 East Japan Earthquake. Uncertainty and fear regarding the possibility of further seismic activity in the near future have been on the rise in the region. The National Disaster Management Research Institute has previously studied and analyzed the overflow characteristics of a tsunami and the rate of flood forecasting through tsunami numerical simulations of the East Sea of South Korea. However, there is currently a significant lack of research on the Southern Coast tsunamis compared to the East Coast. On the Southern Coast, the tidal difference is between 1~4 m, and the impact of the tides is hard to ignore. Therefore, it is necessary to analyze the impact of the tide propagation characteristics on the tsunami. Occurrence regions that may cradle tsunamis that affect the southern coast region are the Ryukyu Island and Nankai Trough, which are active seafloor fault zones. The Southern Coast has not experienced direct damage from tsunamis before, but since the possibility is always present, further research is required to prepare precautionary measures in the face of a potential event. Therefore, this study numerically simulated a hypothetical tsunami scenario that could impact the southern coast of South Korea. In addition, the tidal wave propagation characteristics that emerge at the shore due to tide and tsunami interactions will be analyzed. This study will be used to prepare for tsunamis that might occur on the southern coast through tsunami hazard and risk analysis.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.1
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• pp.18-24
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• 2010

In this study, a tsunami fragility methodology was determined for a probabilistic safety assessment(PSA) induced tsunami event in Nuclear Power Plant(NPP) site. For this purpose, a fragility evaluation method was presented using previous external PSA method. Failure mode and failure criteria about major safety related equipments and structures were determined. Finally, a tsunami fragility assessment was performed for offsite transformer in NPP site. For the fragility evaluation, structural failure like overturning and sliding and functional failure induced by inundation. Through this study, it can be concluded that a functional failure according to inundation height was governed total probability of failure of offsite transformer in NPP.

• Journal of Korea Water Resources Association
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• v.50 no.9
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• pp.647-652
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• 2017

Many islands are scattered around the southern area of the Korean Peninsula and they may be very vulnerable to unexpected tsunami attacks. During the East Japan Tsunami Event occurred on March 11, 2011, many islands located at the southern area were affected by tsunamis. In this study, maximum run-up heights of solitary waves on a circular island with asymmetrical crest lengths investigated by using a numerical model based on the shallow-water theory. The obtained results could be used by local authorities to establish a defense plan against unexpected tsunami invasion.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.1
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• pp.53-59
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• 2021

The purpose of this study is to develop a damper that protects against the dangers of tidal waves since there's no function to block the inflow of large amounts of water into the inside When natural disasters such as tidal waves occur. Therefore, it intended to derive the design data by simulating through flow analysis in order to predict the pressure that a damper configured to open and close manually or automatically receives. It examined the preceding researches first and conducted the flow analysis, to predict the force of the damper installed on the bottom of the building's outside to prevent the inflow of seawater into the inside when natural disaster occurring. As a result, it showed that, in the event of a tsunami, it moved about 170m and the time impacting the damper occurred within about eight seconds, and, at the moment, the damper door was pressured about 17bar. Also, it could identify that the load was approximately 900kN and the force by the fluid was applied to the damper door.