• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.231-234
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• 2008

This paper is concerned with the analysis of elasto-plastic stress waves by a time discontinuous variational integrator based on Hamiltonian in order to more accurate results in one dimensional dynamic problem. The proposed algorithm adopts both time-discontinuous variational integrator and space-continuous Hamiltonian so as to capture discontinuities of stress waves. This study enables to preserve total mechanical energy such as internal energy, kinetic energy and dissipative energy due to plastic deformation for long integration time. Finite element analysis of elasto-plastic stress waves is carried out in order to demonstrate the accuracy of the proposed algorithm.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.5 s.112
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• pp.114-122
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• 2005

Anyang city performed a design competition for the existing paper mill site and this design is the work that was submitted to that competition. The design instructions for the competition were about an organic site which had harmony of aboveground park and underground parking lot, establishment of park planning which is fit for the features of nearby areas, and security of proper parking space. This design criteria set the design concept to a new wave of Anyang by reflecting the design instructions of prize contest and features of the site and developed it as three waves. First, the eco wave, one of three waves, means that it compose the ecological healthy park and urban environment together with restoration and preservation of Suamcheon (stream), and futhermore the waves that the natural resource are maintained in a delicate ecological balance as the water resource of Anyang city are connected to the axis of mountain resource. Secondly, the emotion wave indicates that the wave toward culture and art emotional park that stimulates and fills up the emotion to makes impoverishing modems minds fertile. Thirdly, the health wave means the waves toward a park to keep the sound of minds and bodies of Anyang citizens, and healthy and sound life as well as the waves toward a park to contribute the healthy leap and development of Anyang. These three waves will enrich the park keeping the dynamic relationship mutually and will be a new culture and art code of Anyang city.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.22-28
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• 2005

We investigated the characteristics of the overflow/wave overtopping, induced by the storm surge and high waves in Masan bay and Busan Coast during Typhoon 'Maemi', which landed at the southeast coast of the Korean peninsula on September, of 2003, causing a severe inundation disaster. Characteristics of the water level, increase by the overflow / wave overtopping, were discussed in two patterns. One is the increase of water level in the region, located inside of a bay, like Masan fishing port, and the waves are relatively small. The other is in the open sea, in which the waves act directly, as on the seawall in Suyong bay. In the former region, the water level increase was affected by the storm surge, as well as the long period oscillation and waves. In Masan fishing port, about $80\%$ of the water level increase on the quay wall was caused by the storm surge. In the latter one, it was greatly affected by the wave run-up. In Suyong bay, about $90\%$ of the water level increase on the seawall was caused by the wave run-up.

• Structural Engineering and Mechanics
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• v.72 no.1
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• pp.83-97
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• 2019

In this research, the vulnerability of some reinforced concrete frames with different stories are studied based on the Park-Ang Damage Index. The damages of the frames are investigated under various earthquakes with nonlinear dynamic analysis in IDARC software. By examining the most important characteristics of earthquake parameters, the damage index and vulnerability of these frames are investigated in this software. The intensity of Erias, velocity spectral intensity (VSI) and peak ground velocity (PGV) had the highest correlation, and root mean square of displacement ($D_{rms}$) had the lowest correlation coefficient among the parameters. Then, the particle swarm optimization (PSO) algorithm was used, and the sinusoidal waves were equivalent to the used earthquakes according to the most influential parameters above. The damage index equivalent to these waves is estimated using nonlinear dynamics analysis. The comparison between the damages caused by earthquakes and equivalent sinusoidal waves is done too. The generations of sinusoidal waves equivalent to different earthquakes are generalized in some reinforced concrete frames. The equivalent sinusoidal wave method was exact enough because the greatest difference between the results of the main and artificial accelerator damage index was about 5 percent. Also sinusoidal waves were more consistent with the damage indices of the structures compared to the earthquake parameters.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.1
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• pp.43-51
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• 2020

In this study, numerical analysis was carried out on a complex pressure field of blast waves caused by the detonation of high explosives in various environments. The generated blast waves propagated in the air, upon the sudden release of high energy induced by the explosion. Reflected waves were created when the pressure waves encountered certain obstacles such as the ground or the walls of structures. The propagation of the blast waves and its interaction with the reflected waves were simulated. An adaptive mesh refinement was applied to improve the efficiency of distribution of computer resource, for the computational calculation of the blast wave propagation in a wide open space. In addition, the integration of the calculation domains for the explosive and air were considered when the maximum density of the explosive region was below critical value. The results were verified by comparison with the pressure time history from blast wave experiments performed under two topographical conditions.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.3
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• pp.227-234
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• 2012

This paper describes the remote monitoring of breaking ocean waves generated by Typhoon Nabi, whose name means butterfly in Korean, using a marine X-band radar in the Yongho Man, Busan, Korea. The basic purpose of this study is to investigate the dynamic behavior and to estimate the periods of breaking waves across the surf zone from radar image sequences. In these experiments, the land-based radar system imaged the inshore zone of three miles from the coastline to a isobath of 30 meters. The wave period and the dominant wave direction for breaking ocean waves extracted directly from radar image sequences were 157.4 meters and 298 degrees, respectively. However, the result calculated quantitatively by the continuous wavelet transform (CWT) showed that the period of breaking waves was 154.3 meters. The average difference in breaking wave periods between the value extracted by using EBRL (electronic bearing and range line) of radar and the calculated value by CWT was 3.1 meters, showing that the CWT method is also accurate. These results suggest that a marine X-band radar system is a viable method of monitoring the breaking ocean waves.

• Journal of Korean Society on Water Environment
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• v.31 no.4
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• pp.367-376
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• 2015

The momentum and kinetic turbulent energy carried by the wind to a stratified lake lead to basin-scale motions, which provide a major driving force for vertical and horizontal mixing. A three-dimensional (3D) hydrodynamic model was applied to Lake Tahoe, located between California and Nevada, USA, to simulate the dominant basin-scale internal waves in the deep lake. The results demonstrated that the model well represents the temporal and vertical variations of water temperature that allows the internal waves to be energized correctly at the basin scale. Both the model and thermistor chain (TC) data identified the presence of Kelvin modes and Poincare mode internal waves. The lake was weakly stratified during the study period, and produced large amplitude (up to 60 m) of internal oscillations after several wind events and partial upwelling near the southwestern lake. The partial upwelling and followed coastal jets could be an important feature of basin-scale internal waves because they can cause re-suspension and horizontal transport of fine particles from nearshore to offshore. The internal wave dynamics can be also associated with the distributions of water quality variables such as dissolved oxygen and nutrients in the lake. Thus, the basin-scale internal waves and horizontal circulation processes need to be accurately modeled for the correct simulation of the dissolved and particulate contaminants, and biogeochemical processes in the lake.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.270-282
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• 2020

Analysis: of the propulsion performance considering ship motion in waves is an important factor for the efficient operation of a ship. The interaction between the propeller and the free surface due to the ship motion in waves has a significant influence on the propulsion performance. However, most recent studies regarding the hydrodynamic performance of ships in waves focus on the added resistance, and experimental and numerical data on the propulsion performance considering the ship motion in waves are very rare. In this study, a numerical investigation of the nominal wake in regular head waves is performed for a KVLCC2 model ship for the fully-loaded condition. Phase-averaged wake fields for one period are compared with experimental data measured using Stereo PIV, showing good agreement. The effect of the ship motion on the characteristics of the wake field and the axial velocity in the propeller plane are investigated while varying the wave length.

• Journal of Advanced Research in Ocean Engineering
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• v.2 no.1
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• pp.1-11
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• 2016

The objective of this paper is to present an analytical solution in deep water waves and verify the validity of the theory (Shin, 2015). Hence this is a follow-up to Shin (2015). Instead of a variational approach, another approach was considered for a more accurate assessment in this study. The products of two coefficients were not neglected in this study. The two wave profiles from the KFSBC and DFSBC were evaluated at N discrete points on the free-surface, and the combination coefficients were determined for when the two curves pass the discrete points. Thus, the solution satisfies the differential equation (DE), bottom boundary condition (BBC), and the kinematic free surface boundary condition (KFSBC) exactly. The error in the dynamic free surface boundary condition (DFSBC) is less than 0.003%. The wave theory was simplified based on the assumption tanh $D{\approx}1$ in this paper. Unlike the perturbation method, the results are possible for steep waves and can be calculated without iteration. The result is very simple compared to the 5th Stokes' theory. Stokes' breaking-wave criterion has been checked in this study.

• Structural Engineering and Mechanics
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• v.85 no.3
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• pp.305-314
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• 2023

The article is about the theoretical analysis of the transmission and reflection of elastic waves through the interface of perfectly connected materials. The solid continuum mediums considered are piezoelectric semiconductors and transversely isotropic in nature. The connection among the mediums is considered in such a way that it holds the continuity property of field variables at the interface. The concept of strain and stress introduced by non-local theory is also being involved to make the study more applicable It is found that, the incident wave results in the generation of four reflected and three transmitted waves including the thermal and elastic waves. The thermal waves generated in the medium are encountered by using the concept of three phase lag heat model along with fractional ordered time thermoelasticity. The results obtained are calculated graphically for a ZnO material with piezoelectric semiconductor properties for medium M₁ and CdSc material with transversely isotropic elastic properties for medium M₂. The influence of fractional order parameter, non-local parameter, and steady carrier density parameter on the amplitude ratios of reflected and refraction waves are studied graphically by MATLAB.