• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.571-574
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• 2004

Clusters of galaxies are filled with X-ray emitted hot gas with the temperature of T ${\~}$2-10 keV. Recent X-ray observations have been revealing unexpectedly that many cluster cores have complicated, peculiar X-ray structures, which imply dynamical motion of the hot gas. Moreover, X-ray spectra indicate that radiative cooling of the cool gas is suppressed by unknown heating mechanisms (the 'cooling flow problem'). Here we propose a novel mechanism reproducing both the inhomogeneous structures and dynamics of the hot gas in the cluster cores, based on state-of-the-art hydrodynamic simulations. We showed that acoustic-gravity waves, which are naturally expected during the process of hierarchical structure formation of the universe, surge in the X-ray hot gas, causing a serous impact on the core. This reminds us of tsunamis on the ocean surging into an distant island. We found that the waves create fully-developed, stable turbulence, which reproduces the complicated structures in the core. Moreover, if the wave amplitude is large enough, they can suppress the cooling of the core. The turbulence could be detected in near-future space X-ray missions such as ASTRO-E2.

• 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 Ocean Engineering and Technology
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• v.28 no.1
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• pp.12-19
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• 2014

Tsunamis are ocean waves generated by movements of the Earth's crust. Several geophysical events can lead to this kind of catastrophe: earthquakes, landslides, volcanic eruptions, and other mechanisms such as underwater explosions. Most of the damage associated with tsunamis are related to their run-up onto the shoreline. Therefore, effectively predicting the run-up process is an important aspect of any seismic sea wave mitigation effort. In this paper, a numerical simulation of the behaviors of a floating body near a quaywall during a tsunami is conducted by using a particle method. First, a solitary wave traveling over shallow water with a slope is numerically simulated, and the results are compared with experiments and other numerical results. Then, the behaviors of floating bodies with different drafts are investigated numerically.

• Journal of the Korean Society of Hazard Mitigation
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• v.4 no.2 s.13
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• pp.71-76
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• 2004

To investigate the inundation of tsunamis in the vicinity of a circular island, a numerical model has been developed based on quadtree grids. The governing equations of the model are the nonlinear shallow-water equations. The governing equations are discretized explicitly by using a finite difference leap-frog scheme on adaptive hierarchical quadtree grids. The quadtree grids are generated around a circular island where refined with rectangular or circular domain. Obtained numerical results have been verified by comparing to available laboratory measurements of run-up heights. A good agreement has been achieved.

• Journal of Korea Water Resources Association
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• v.51 no.11
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• pp.941-950
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• 2018

Tsunamis that have occurred around the Pacific Ocean rim over the past decades have taken a heavy toll on lives of human beings and property. The Eastern Coast of the Korean Peninsula is not safe from sudden tsunami attacks and has sustained tsunami damage in the past. In this review, the past, present, and future of some aspects of tsunami research in Korea have been introduced extensively. Tsunamis in Korea, numerical model simulating tsunami behaviors and laboratory experiments will be discussed. In the compainion review, field surveys for domestics and overseas tsunami events, countermeasures against tsunami attacks, furture research topics and concluding remarks will be described.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5B
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• pp.551-555
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• 2006

In this study, new dispersion-correction terms are added to a leap-frog finite difference scheme for the linear shallow-water equations with the purpose of considering dispersion effects of the linear Boussinesq equations for propagation of tsunamis. The numerical model developed in this study is tested to the problem that the initial free surface displacement is a Gaussian hump over a constant water depth, and the predicted numerical results are compared with analytical solutions. The results of the present numerical model are accurate in comparison with those of existing models.

• Ocean and Polar Research
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• v.29 no.1
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• pp.9-31
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• 2007

Most seismic sea waves in the East Sea originate from earthquakes occurring near the Japanese west coast. While the waves propagate in the East Sea, they are deformed by refraction, diffraction and scattering. Though the Boussinesq equation is most applicable for such wave phenomena, it was not used in numerical modelling of seismic sea waves in the East Sea. To examine characteristics of seismic sea waves in the East Sea, numerical models based on the Boussinesq equation are established and used to simulate recent tsunamis. By considering Ursell parameter and Kajiura parameter, it is proved that Boussinesq equation is a proper equation for seismic sea waves in the East Sea. Two models based on the Boussinesq equation and linear wave equation are executed with the same initial conditions and grid size ($1min{\times}1min$), and the results are compared in various respects. The Boussinesq equation model produced better results than the linear model in respect to wave propagation and concentration of wave energy. It is also certified that the Boussinesq equation model can be used for operational purpose if it is optimized. Another Boussinesq equation model whose grid size is $40sec{\times}30sec$ is set up to simulate the 1983 and 1993 tsunamis. As the result of simulation, new propagation charts of 2 seismic sea waves focused on the Korean east coast are proposed. Even though the 1983 and 1993 tsunamis started at different areas, the propagation paths near the Korean east coast are similar and they can be distinguished into 4 paths. Among these, total energy and propagating time of the waves passing over North Korea Plateau(NKP) and South Korea Plateau(SKP) determine wave height at the Korean east coast. In case of the 1993 tsunami, the wave passing over NKP has more energy than the wave over SKP. In case of the 1983 tsunami, the huge energy of the wave passing over SKP brought about great maximum wave heights at Mukho and Imwon. The Boussinesq equation model established in this study is more useful for simulation of seismic sea waves near the Korean east coast than it is the Japanese coast. To improve understanding of seismic sea waves in shallow water, a coastal area model based on the Boussinesq equation is also required.

• Proceedings of the KSRS Conference
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• v.1
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• pp.43-46
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• 2006

The main tsunami wave triggered by the December 2004 Sumatra tsunami was detected in the ocean south of India by satellite altimeters on Jason, Topex/Poseidon and Envisat. All three altimeters also detected shorter-wavelength (10 to 100 km), slower-propagating surface waves, spreading from the site of the earthquake. The shorter waves give additional information about the tsunami event, and can be used to better define the generating region in this, and future tsunamis. The properties of the area of shorter tsunami-generated waves may also be important in designing a future satellite-based detection system.

• Coupled systems mechanics
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• v.5 no.2
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• pp.145-156
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• 2016

An efficient and general numerical strategy for fluid-structure interaction problems is presented where either the fluid or the structure part are represented by nonlinear models. This partitioned strategy is implemented under the form of code coupling that allows to (re)-use previous made developments in a more general multi-physics context. This strategy and its numerical implementation is verified on classical fluid-structure interaction benchmarks, and then applied to the impact of tsunamis waves on submerged structures.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2000.09a
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• pp.47-54
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• 2000

역사적으로 동해에서의 쓰나미는 자주 발생하지는 않았지만, 동해에서의 지진 진앙지가 유라시아와 북태평양 플레이트사이인 일본연안을 따라 위치하고 있어서 우리나라의 동해 연 안, 일본연안 및 러시아 연안에 큰 쓰나미에 의한 피해를 줄 수 있다. (중략)