• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.91-96
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• 2013

In this paper, vibration response of gravity-type caisson breakwater is analyzed to suggest the direction for structural health monitoring (SHM) on harbor caisson structure. To achieve the objective, the following approaches are implemented. Firstly, vibration analysis methods are selected to examine the dynamic characteristics of the lab-scale caisson in the frequency and the modal domain. Secondly, vibration tests on the lab-scale caisson breakwater which is installed in 2-D wave tank were performed under several water level conditions. Thirdly, vibration response of the lab-scale caisson were analyzed in the frequency and modal domain. Finally, the direction of SHM for gravity-type caisson breakwater was suggested.

• 한국해양공학회지
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• 제33권1호
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• pp.61-67
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• 2019

Recently, a perforated caisson breakwater with turning wave blocks was developed to improve the water affinity and public safety of a rubble mound armored by TTP. In this study, hydraulic model tests were performed to examine the hydraulic performance of a non-porous caisson and new caisson breakwater with perforated blocks for attacking waves in a small fishery harbor near Busan. The model test results showed that the new caisson was more effective in dissipating the wave energy under normal wave conditions and in reducing the wave overtopping rates under design wave conditions than the non-porous caisson. It was found that the horizontal wave forces acting on the perforated caisson were slightly larger than those on the non-porous caisson because of the impulsive forces on the caisson with the turning wave blocks.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 1996년도 정기학술강연회 발표논문 초록집
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• pp.176-183
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• 1996

In order to reduce wave reflection from a breakwater, a perforated wall caisson is often used. A conventional perforated wall caisson breakwater for which the water depth inside the wave chamber is the same as that on the rubble mound berm has less weight than a vertical solid caisson with the same width and moreover the weight is concentrated on the rear side of the caisson. (omitted)

• 한국해안해양공학회지
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• 제17권4호
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• pp.213-220
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• 2005

소파케이슨 방파제의 기대활동량 산정방법을 제안하였다. 소파케이슨의 활동량 산정을 위해 필요한 파력의 시계열은 기존에 개발된 소파케이슨의 정적 파력모델을 동적으로 확장하여 개발하였다. 충격파와 중복파의 구성은 지속시간 및 최대파력을 이용하여 구하였다. 수치해석에서는 제안방법에 의한 소파케이슨의 1파에 대한 활동량 및 50년간의 기대활동량을 직립케이슨에 적용하는 기존방법의 결과와 비교하였다. 비고결과 제안방법에 의한 소파케이슨의 활동량은 기존방법을 적용할 때보다 감소하는 것으로 나타났다.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.159-162
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• 2007

The numerical efforts are presented for investigation of irregular waves passing a slit cassion and a warock block breakwater. In the numerical model, the Reynolds equations are solved by a finite difference method and $k-\varepsilon$ model is employed for the turbulence analysis. To track the free surface displacement, the volume of fluid method(VOF) is employed. Numerical predictions of reflection and transmission coefficients are compared with those of the warock block breakwater with the slit caisson. Energy dissipation and seawater exchange rates of the slit caisson are better than those of the warock block breakwater.

• 산업기술연구
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• 제31권B호
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• pp.81-90
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• 2011

Centrifuge modeling and numerical analysis on works of breakwater construction were performed to investigate the behavior of caisson type of breakwater and foundation treated with the method of DCM (Deep Cement Mixing) under the condition of wave action in field. In centrifuge modeling, construction sequence of breakwater caisson such as preparation of ground, treatment of DCM, installation of rubble mound, placement of breakwater caisson and lateral loading on the breakwater due to wave action were reconstructed. Lateral movement of model breakwater and ground reaction in the vertical direction were monitored during test. Stress concentration ratio between the untreated ground and the treated ground with DCM was evaluated from measurement of vertical stresses on each ground. Numerical analysis with the software of PLAXIS was carried to compare with Results of centrifuge model test. It was found that stability of model breakwater was maintained during stage of construction and the compared results about stress concentration ratio were in relatively good agreements.

• 한국해양공학회지
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• 제15권4호
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• pp.20-27
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• 2001

Recently numerical approaches for wave loads acting on the vertical caisson of breakwater, and resulting wave reflection and transmission coefficients have been performed. Although the numerical studies by Sulisz's(1997) and Kim et al.(2000) are suggested representatively, theoretical formulation for nonlinear wave pressure is not developed yet. And experimental results of Sulisz(1997) revealed that nonlinear uplift pressure on the caisson may be produced largely on the case of caisson founded on the high rubble mound. From the results of this study, the nonlinear theory for the uplift wave pressure acting on the caisson by applying boundary integral method of Green theorem is formulated, and also the characteristics of nonlinear uplift pressure and run-up height on the caisson are evaluated numerically, according to the variations of hydraulic properties of the rubble mound.

• 한국해안·해양공학회논문집
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• 제21권3호
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• pp.209-215
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• 2009

케이슨식 방파제의 신뢰성해석 시 파고와 조위의 확률변동성을 고려하기 위한 하중면 이용방법을 제안하였다. 케이슨식 방파제 전면에 전달되는 수평파력과 양력을 전면조위와 파고의 일차함수로 추정하였으며 추정한 하중면을 일계신뢰도법을 이용한 신뢰성 해석에 적용하였다. 수치해석에서 하중면을 이용한 케이슨식 방파제의 활동 및 전도 파괴확률을 산정하였으며 몬테카를로 모사법의 결과와 비교하였다.

• Smart Structures and Systems
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• 제24권4호
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• pp.525-539
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• 2019

In this study, vibration characteristics of a gravity-based caisson-foundation breakwater system are investigated for ambient and geometric parameters such as various waves, sea levels, and foundation conditions. To achieve the objective, following approaches are implemented. Firstly, operational modal analysis methods are selected to identify vibration modes from output-only dynamic responses. Secondly, a finite element model of an existing caisson-foundation breakwater system is established by using a structural analysis program, ANSYS. Thirdly, forced vibration analyses are performed on the caisson-foundation system for two types of external forces such as controlled impacts and wave-induced dynamic pressures. For the ideal impact, the wave force is converted to a triangular impulse function. For the wave flow, the wave pressure acting on the system is obtained from wave field analysis. Fourthly, vibration modes of the caisson-foundation system are identified from the forced vibration responses by combined use of the operational modal analysis methods. Finally, vibration characteristics of the caisson-foundation system are investigated under various waves, sea levels, and foundations. Relative effects of foundation conditions on vibration characteristics are distinguished from that induced by waves and sea levels.

• 한국해안·해양공학회논문집
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• 제29권6호
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• pp.286-304
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• 2017

본 연구에서는 어항 등과 같은 소규모 항에서 적용 가능한 격자블록결속에 의한 신형식의 원형유공케이슨을 제안하고, 이러한 방파제의 수리특성을 수치적으로 검토하였다. 본 연구에서 적용한 수치해석 코드는 최근들어 다양한 분야에서 공학적 문제해결을 위해 그 사용예가 급증하고 있는 공중사용허가서(오픈소스 기반) 라이선스 기반의 OpenFOAM(Open Field Operation and Manipulation)에 조파모듈, 투과층 해석모듈, 및 반사파 제어기능 등을 추가한 OLAFOAM을 적용하였다. 본 연구는 먼저, 1) 규칙파 하 3차원슬리트케이슨 방파제에서 파의 파압변동에 대해 기존의 실험 결과와 비교 검토하고, 2) 불규칙파를 조파하여 목표한 파의 재현과 주파수스펙트럼을 비교 검토하여 OLAFOAM의 타당성을 검증하였다. 이로부터 슬리트케이슨과 유사한 원형유공케이슨이 설치된 일정수심의 3차원수치파동수조에 불규칙파를 조파하여 유수실 폭과 유의파고 및 유의주기의 변화에 따른 원형유공케이슨 방파제에서 월파량, 반사율, 파압분포 및 그들의 상호연관성을 면밀히 검토 분석하였다. 이로부터 파압분포는 불투과연직벽체에 대한 Goda 식의 결과보다 매우 작은 결과를 나타내었으며, 반사율은 기존의 슬리트케이슨에서 반사율의 변동범위 내에 존재하는 것을 알 수 있었다.