• International Journal of Ocean System Engineering
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• 제1권3호
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• pp.155-164
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• 2011

The second-order motion characteristics of a semi-submersible are investigated in regular waves. A higher-order boundary element method in a frequency domain and a finite element method in a time-domain were applied to the numerical analysis of the nonlinear hydrodynamic force and motion characteristics of semi-submersibles in view point of potential flow. Various aspects of nonlinear effects on the heave and roll of a semi-submersible were numerically investigated and some selected cases were compared with the model test data.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2002년도 추계공동학술대회논문집
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• pp.133-138
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• 2002

우리나라가 세계 물류기지의 중심 곽으로 발전하기 위해서는 날의 급증하고 있는 물류량을 처리하기 위한 항만의 건설이 시급한 과제이다. 국토가 좁고 대도시에 인구가 집중하친 있으나 삼면이 바다로 둘러 쌓여 있는 우리나라의 경우에는 해양공간개발이 필요하다. 증가하는 물류량을 처리할 수 있는 항만의 건설을 위하여 본 연구에서는 초대형 부유체식 컨테이너 야드를 제안하고, 해상에 설치되는 초대형 부유체식 컨테이너야드가 파의 길이, 부유체 구조물의 강성, 해역의 수심, 입사하는 파의 방향 능에 따라서 어떠한 응답특성을 나타내는지 파악한다.

• Structural Engineering and Mechanics
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• 제74권3호
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• pp.381-394
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• 2020

The structural performance of cold-formed steel (CFS) built-up battened columns were numerically investigated in this paper. The built-up column sections were formed by connecting two-lipped channels back-to-back, with a regular spacing of battens plates, and have been investigated in the current study. Finite element models were validated with the test results reported by the authors in the companion paper. Using the validated models, the parametric study was extended, covering a wider range of overall slenderness to assess the accuracy of the current design rules in predicting the design strengths of the CFS built-up battened columns. The parameters viz., overall slenderness, different geometries, plate slenderness (b/t ratio) and yield stress were considered for this study. In total, a total of 228 finite element models were analyzed and the results obtained were compared with current design strength predicted by Effective Width Method of AISI Specifications (AISI S100:2016) and European specifications (EN1993-1-3:2006). The parametric study results indicated that the current design rules are limited in predicting the accuracy of the design strengths of CFS built-up battened columns. Therefore, a design equation was proposed for the AISI and EC3 specifications to predict the reliable design strength of the CFS Built-up battened columns and was also verified by the reliability analysis.

• 한국항해항만학회지
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• 제27권1호
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• pp.49-54
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• 2003

우리나라가 세계 물류기지의 중심 국으로 발전하기 위해서는 날로 급증하고 있는 물류량을 처리하기 위한 항만의 건성이 시급한 과제이다. 국토가 좁고 대도기에 인구가 급증하고 있으나 삼면이 바라도 둘러 쌓여 잇는 우리나라의 경우에는 해양공간개발이 필요하다. 증가하는 물류량은 처리할 수 있는 항만의 건설을 위하여 본 연구에서는 초대형 부유채식 컨테이너 야드를 제안하고 해상에 설치되는 초대형 부유채식 컨테이너 야드가 파의 길이 , 해역의 수심, 입사하는 파의 방향등에 따라서 어떠한 응답특성을 나타내는지 파악한다.

• Coupled systems mechanics
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• 제2권1호
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• pp.111-126
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• 2013

The structural design requirements of an offshore platform subjected to wave induced forces and moments in the jacket can play a major role in the design of the offshore structures. For an economic and reliable design; good estimation of wave loadings are essential. A nonlinear response analysis of a fixed offshore platform under structural and wave loading is presented, the structure is discretized using the finite element method, wave plus current kinematics (velocity and acceleration fields) are generated using 5th order Stokes wave theory, the wave force acting on the member is calculated using Morison's equation. Hydrodynamic loading on horizontal and vertical tubular members and the dynamic response of fixed offshore structure together with the distribution of displacement, axial force and bending moment along the leg are investigated for regular and extreme conditions, where the structure should keep production capability in conditions of the 1-yr return period wave and must be able to survive the 100-yr return period storm conditions. The result of the study shows that the nonlinear response investigation is quite crucial for safe design and operation of offshore platform.

• 한국해양공학회지
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• 제24권6호
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• pp.16-22
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• 2010

In this paper, the diffraction problems for fixed offshore structures are solved using a hybrid scheme. In this hybrid scheme, potential-based solutions and the Navier-Stokes-based finite volume method (FVM) with a volume-of-fluid (VOF) method are combined. We introduce a buffer zone for efficient wave-making and damping. In this buffer zone, the near field solution from FVM-VOF is gradually changed to Stokes' 2nd order wave solutions. Three different models, including the truncated cylinder, sphere, and wigleyIII model, are numerically investigated in regular waves with a wave steepness of 1/30. The efficiency and accuracy of the hybrid scheme are numerically validated from results using different domain sizes and buffer zones. The wave exciting forces from the FVM-VOF simulations are compared with experiments and potential-based solutions from the higher-order boundary element method (HOBEM). This comparison shows good agreement between the hybrid scheme and potential-based solutions.

• 한국기계가공학회지
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• 제20권11호
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• pp.100-107
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• 2021

The use of new and renewable energy is essential to solve the problem of increasing fossil fuel use due to industrial development. The paradigm of the automobile industry has changed due to the strengthening of environmental regulations in developed countries, and the development of eco-friendly cars is underway. Fuel cell electric vehicles (FCEVs), which use hydrogen as fuel, require strict standards for fuel-related components. In particular, check valves for FCEV control high-pressure hydrogen and thus, must be sufficiently strong for the challenging environment caused by high-pressure hydrogen. Therefore, this study used DEFORM 3D, a regular finite element analysis program, to check the moldability of check valves for FCEV, design the process, verify reliability through single streamline analysis, tensile tests, and ANSYS simulations, and identify suitable materials for the high-pressure hydrogen environment.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.1064-1081
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• 2014

This paper presents a numerical analysis of slamming and whipping using a fully coupled hydroelastic model. The coupled model uses a 3-D Rankine panel method, a 1-D or 3-D finite element method, and a 2-D Generalized Wagner Model (GWM), which are strongly coupled in time domain. First, the GWM is validated against results of a free drop test of wedges. Second, the fully coupled method is validated against model test results for a 10,000 twenty-foot equivalent unit (TEU) containership. Slamming pressures and whipping responses to regular waves are compared. A spatial distribution of local slamming forces is measured using 14 force sensors in the model test, and it is compared with the integration of the pressure distribution by the computation. Furthermore, the pressure is decomposed into the added mass, impact, and hydrostatic components, in the computational results. The validity and characteristics of the numerical model are discussed.

• 한국지진공학회논문집
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• 제13권3호
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• pp.21-28
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• 2009

지반-말뚝-구조의 상호작용을 정밀하게 해석하기 위해서는 토층, 말뚝 그리고 구조물의 적절한 묘사가 필요하다. 일반적으로 사용하는 유한요소해석의 경우에는 지반이나 구조물의 물성이 바뀌는 경계를 따라서 요소의 경계가 정해지게 된다. 그러나 실제로는 토층 단면과 말뚝의 형상이 매우 복잡하여 요소의 배열이 매우 어려운 작업이 될 수 있다. 이 어려움을 해결하기 위하여, 이 논문에서는 불연속선의 위치에 관계없이 규칙적인 요소를 사용하여 쉽게 적분을 가능하게 하는 다른 적분 방법을 채택하였다. 이 방법을 적용함으로 써 요소는 매우 빠르고 규칙적인 강성 매트릭스를 만든다. 구조물 응답에 대한 토층과 말뚝의 영향을 조사하였고, 예를 통하여 본 방법의 유효성을 보였다. 탄성 말뚝의 사용으로 20% 대의 가속도 감소 효과를 얻었고 지반 층의 모양에 따라 그 영향이 변하는 것을 확인하였다.

• 동력기계공학회지
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• 제15권1호
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• pp.64-71
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• 2011

The Tension Leg Platform(TLP) is restrained from oscillating vertically by tethers(or tendons), which are vertical anchor lines tensioned by the platform buoyancy larger than the platform weight. Thus a TLP is a compliant structure which allows lateral movements of surge, sway, and yaw but restrains heave, pitch, roll. In this paper, the motions of a TLP in current and waves were investigated. Hydrodynamic forces and wave exciting forces acting on the TLP were evaluated using the three dimensional source distribution method. The motion responses and tension variations of the TLP were analyzed in the case of including current or not including one in regular waves and effects of current on the TLP were investigated.