• Structural Engineering and Mechanics
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• 제85권5호
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• pp.645-654
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• 2023

Based on first-order shear deformation theory, a wave propagation model of graphene platelets reinforced metal foams (GPLRMFs) circular plates is built in this paper. The expressions of phase-/group- velocities and wave number are obtained by using Laplace integral transformation and Hankel integral transformation. The effects of GPLs pattern, foams distribution, GPLs weight fraction and foam coefficient on the phase and group velocity of GPLRMFs circular plates are discussed in detail. It can be inferred that GPLs distribution have great impacts on the wave propagation problems, and Porosity-I type distribution has the largest phase velocity and group velocity, followed by Porosity-III, and finally Porosity-II; With the increase of the GPLs weight fraction, the phase- and group- velocities for the GPLRMFs circular plate will be increased; With the increase of the foam coefficient, the phase- and group- velocities for the GPLRMFs circular plate will be decreased.

• 대한토목학회논문집
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• 제14권3호
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• pp.595-605
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• 1994

해운대(海雲臺) 해수욕장(海水浴場)의 단(短) 장기적(長期的)인 해빈변형기구(海濱變形機構)를 파악하기 위하여 기존자료(旣存資料)의 수집분석(收集分析), 현지조사(現地調査) 및 수치모형실험(數値模型實驗)을 실시하였다. 해안선(海岸線) 및 해빈기면(海濱祈面) 측정자료(測定資料)의 해석(解釋)을 통하여 태풍통과(颱風通過)에 의한 해빈(海濱)의 퇴적(堆積) 및 침식기구(浸蝕機構)를 모식적(模式的)으로 설명하였다. 이러한 단기적(短期的)인 해빈변형기구(海濱變形機構)는 입사파(入射波)의 파향(波向)과 쇄파대(碎波帶)에서 발생하는 해빈류(海濱流)와 밀접한 관계(關係)가 있는 것으로 나타났다. 그리고 해빈폭(海濱幅) 실측자료(實測資料)를 이용한 해안선변형모형(海岸線變形模型)의 검증(檢證)을 통하여 대표파(代表波)의 제원(諸元)과 검증(檢證)파라미터를 도출하였다. 해운대(海雲臺) 해안(海岸)은 주입사(主入射) 파향(波向)이 SE계(系)이므로 장기적(長期的)으로는 동쪽에서 서쪽으로의 연안표사(沿岸漂砂)가 탁월하게 존재한다. 따라서 동쪽해안에서는 표사(漂砂)의 공급원(供給源)이 없으므로 해안침식(海岸浸蝕)을 일으키게 되고, 서쪽해안에 퇴적(堆積)한 모래는 폭풍시(暴風時) 고파랑(高波浪)에 의하여 외해(外海)쪽으로 유실(流失)된다.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1992년도 정기학술강연회 발표논문 초록집
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• pp.77-82
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• 1992

쇄파역이 포함된 연안해역에 구조물등이 설치될 경우, 심해에서 발달하여 진행해온 파랑은 구조물 주변에서 반사 및 회절에 기인하여 지배적으로 변형하여 주변해역의 파랑장이 변화하게 되며, 특히 쇄파대에 위치한 구조물 주변에서는 복잡한 파랑변형 양상을 나타내게 된다.(중략)

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1992년도 정기학술강연회 발표논문 초록집
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• pp.84-89
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• 1992

파랑변형 예측모델로서는 타원형 편미분 방정식 형태인 완경사 방정식(Berkhoff, 1972)이 있으며 이는 파랑의 굴절, 회절, 반사등의 변형을 재현할 수 있으나 수치해석상 어려운점이 있으며 많은 기억용량과 계산시간이 소요되어 일반적이지 못한 단점이 있다.(중략)

• 한국항만학회지
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• 제13권1호
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• pp.155-166
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• 1999

The construction of the coastal structures and reclamation work causes the circulation reduced in the semi-closed inner water area and the unbalanced sediment budget of beach results in an alteration of beach topography. Among the various fluid motions in the nearshore zone water particle motion due to wave and wave-induced currents are the most responsible for sediment movement. Therefore it is needed to predict the effect of the environmental change because of development and so the prediction of wave transformation dose. The purpose of this study is to introduce the relation between waves wave-induced currents and sediment movement. In this study we will show numerical method using energy conservation equation involving reflection diffraction and reflection and the surfzone energy dissipation term due to wave breaking is included in the basic equation. For the wave-induced current the momentum equation was combined with radiation stresses lateral mixing and friction Various information is required in the prediction of wave-induced current depending on the prediction tool. We can predict changes in wave-induced current from the distribution of wave especially near the wave breaking zone. To evaluate these quantities we have to know the local condition of waves mean sea level and so on. The results from the wave field and wave-induced current field deformation models are used as input data of the sediment transport and bottom change model. Numerical model were established by a finite difference method then were applied to the development plan of the eastern Pusan coastal zone Yeonhwa-ri and Daebyun fishing port. We represented the result with 2-D graphics and made comparison between before and after development.

• 한국해안해양공학회지
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• 제7권2호
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• pp.141-147
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• 1995

파랑변형을 계산하는 여러가지 수치모형이 제안되어 있다. 그 중에서도 선유량과 수면변위로 나타내는 시간의존 완경사방정식을 이용한 수치모형이 반사파가 존재하는 파랑장에서는 지금까지 널리 사용되고 있다. 이 경우 경사지게 입사하는 파에 대하여 파랑장의 외해경계 뿐만 아니라 측방경계 중, 하나는 입사경계로 처리되어야 한다. 본 연구에서는 측방입사경계 처리 방법으로서, Maruyama와 Kajima(1985), Copeland(1985), 그리고 Ohnaka와 Watanabe(1987)의 방법을 고려한 후, 파고비, 파향 그리고 위상의 계산결과치로 각 방법들의 특성을 비교 분석하였다. 그 결과 Ohnaka와 Watanabe(1987)의 방법이 일반적인 해저경사를 가진 파랑장에서 가장 적절한 측방입사경계 처리 방법인 것을 알 수 있었다.

• Structural Engineering and Mechanics
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• 제66권4호
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• pp.495-504
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• 2018

The current study is dedicated to study the thermal effects of wave propagation in beams, reinforced by carbon nanotubes (CNT). Beams, made up of carbon nanotube reinforced composite (CNTRC) are the future materials in various high tech industries. Herein a Winkler elastic foundation is assumed in order to make the model more realistic. Mostly, CNTs are pervaded in cross section of beam, in various models. So, it is tried to use four of the most profitable reconstructions. The homogenization of elastic and thermal properties such as density, Yong's module, Poisson's ratio and shear module of CNTRC beam, had been done by the demotic rule of mixture to homogenize, which gives appropriate traits in such settlements. To make this investigation, a perfect one, various shear deformation theories had been utilized to show the applicability of this theories, in contrast to their theoretical face. The reigning equation had been derived by extended Hamilton principle and the culminant equation solved analytically by scattering relations for propagation of wave in solid bodies. Results had been verified by preceding studies. It is anticipated that current results can be applicable in future studies.

• 한국해안해양공학회지
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• 제5권4호
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• pp.350-356
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• 1993

본 연구에서는 천수역 비선형 방정식인 Boussinesq 방정식을 방파제에 의한 산란문제에 적용하였다. 방파제에 의한 파랑변형을 수치계산하기 위하여 경계치문제는 유한요소법을 사용하였고 시간에 따른 진행은 Runge-Kutta 방법을 사용하였다. 수치모델로 2차원 수로에 입사파의 진행방향과 수직으로 방파제가 놓여있는 경우를 생각하였으며 방파제의 길이와 두께변화에 따른 파랑변형에 미치는 영향을 살펴보았다. 또한 후류 경계면이 막혀있는 경우와 열려있는 경우를 고려하였으며 선형결과와 비선형결과의 차이를 살펴보았다.

• 대한기계학회논문집B
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• 제29권8호
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• pp.921-926
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• 2005

In the idealized model problem of the interaction between a planar travelling shock and a symmetric vortex, the physics of shock distortion and quadrupole sound generation are well known to many researchers. However, the authors have distinguished the weak waves reflected and transmitted by the complicated photograph images obtained from a shock tube experiment. In this paper, we introduces a parametric study based on Navier-Stokes simulation and Rankin vortex model to see the difference of shock deformation shapes. Four combination of the strength of shock and vortex are respectively selected from a parameter plane of shock and vortex strength extended to the strong vortex region. The result shows clearly discernable wave morphology for the main parameters, which is not yet explicitly mentioned by other researchers.

• International Journal of Advanced Culture Technology
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• 제8권2호
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• pp.159-164
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• 2020

The response analysis of frame structure with open section beams considering warping conditions and short duration load have been performed. When a beam of frame structure is subjected under torsional moment, the cross section will deform a warping as well as twist. For some thin-walled sections warping will be large, and accompanying warping restraint will induce axial and shear stresses and reduce the twist of beam which stiffens the beam in torsion. Because of impact or blast loads, the wave propagation effects become increasingly important as load duration decreases. This paper presents that a warping restraint in finite element model effects the behavior of beam deformation, dynamic mode shape and response analysis. The computer modelling of frame is discussed in linear beam element model and linear thin shell element model, also presents a correlation between computer predicted and actual experimental results for static deflection, natural frequencies and mode shapes of frame. A method to estimate the number of normal modes that are important is discussed.