• 제목/요약/키워드: Floating Architecture

검색결과 433건 처리시간 0.023초

Dynamic characteristics between waves and a floating cylindrical body connected to a tension-leg mooring cable placed in a simulated offshore environment

  • Song, Juhun;So, Soo-Hyun;Lim, Hee-Chang
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제8권4호
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    • pp.375-385
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    • 2016
  • Given the rapid progress made in understanding the dynamics of an offshore floating body in an ocean environment, the present study aimed to simulate ocean waves in a small-sized wave flume and to observe the motion of a cylindrical floating body placed in an offshore environment. To generate regular ocean waves in a wave flume, we combined a wave generator and a wave absorber. In addition, to precisely visualise the oscillation of the body, a set of light-emitting diode illuminators and a high-speed charge-coupled device camera were installed in the flume. This study also focuses on the spectral analysis of the movement of the floating body. The wave generator and absorbers worked well to simulate stable regular waves. In addition, the simulated waves agreed well with the plane waves predicted by shallow-water theory. As the period of the oncoming waves changed, the movement of the floating body was substantially different when tethered to a tension-leg mooring cable. In particular, when connected to the tension-leg mooring cable, the natural frequency of the floating body appeared suddenly at 0.391 Hz as the wave period increased.

Effect of Wave Load on the Member Force of Steel Structure of Floating Buildings

  • Lee, Young-Wook;Park, Tae-Jun
    • 국제강구조저널
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    • 제18권4호
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    • pp.1431-1439
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    • 2018
  • For floating buildings may fl oat on the water for a long time, they are constantly affected by various environmental loads such as wind and wave loads. In this study to find the wave effect on the floating building, five models are designed using steel moment resisting frame. It is assumed that the lower part of the floating building is a reinforced concrete pontoon, while the upper part is a three-story steel frame. To analyze floating buildings affected by wind and wave loads, hydro-dynamic and substructure analysis are performed. As input loads, this study set limits that the mean wind velocity is 35 m/s and the significant wave height is 0.5 m for the residential building. From the hydrodynamic analysis, the time-history acceleration of building is obtained and transformed into a base ground input for a substructure analysis of the superstructure of the building. Finally the mean of the maximum from 30 dynamic analysis of the floating buildings are used to be compared with the results of the same model on the ground. It was shown that the dynamic results with wind and wave loads are not always lesser than the static results which are calculated with static equivalent wind load for a building that is located on the ground.

Hydrodynamic analysis of a floating body with an open chamber using a 2D fully nonlinear numerical wave tank

  • Uzair, Ahmed Syed;Koo, Weon-Cheol
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제4권3호
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    • pp.281-290
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    • 2012
  • Hydrodynamic analysis of a surface-piercing body with an open chamber was performed with incident regular waves and forced-heaving body motions. The floating body was simulated in the time domain using a 2D fully nonlinear numerical wave tank (NWT) technique based on potential theory. This paper focuses on the hydrodynamic behavior of the free surfaces inside the chamber for various input conditions, including a two-input system: both incident wave profiles and forced body velocities were implemented in order to calculate the maximum surface elevations for the respective inputs and evaluate their interactions. An appropriate equivalent linear or quadratic viscous damping coefficient, which was selected from experimental data, was employed on the free surface boundary inside the chamber to account for the viscous energy loss on the system. Then a comprehensive parametric study was performed to investigate the nonlinear behavior of the wave-body interaction.

파랑하중을 받는 초대형 부유식 구조물 상부구조체의 실용정적해석법 (Simplified Static Analysis of Superstructure on Very Large Floating Structures subjected to Wave Loads)

  • 송화철;박효선;서지현
    • 한국항해항만학회지
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    • 제27권5호
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    • pp.519-526
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    • 2003
  • 초대형 부유식 구조물의 초기 설계단계에서 부체구조물과 상부구조물을 분리하여 해석하는 것이 일반적이며, 부체의 탄성응답해석의 변형모드를 이용하여 상부구조물의 주각부에 강제수직변위를 입력하여 파랑하중에 의한 영향을 고려한다. 하지만 이와 같은 해석법의 경우 각 지점에 변위하중을 입력하는데 어려움이 있다. 본 논문에서는 파랑하중을 지점변위하중으로 직접 입력하지 않고 고정하중과 적재하중에 의한 강도설계 결과를 이용하여 파랑하중의 영향을 증폭계수의 형태로 도출하는 근사 실용정적해석법을 제안한다. 이 연구에서는 4경간 3층 구조물을 예제로 하여 파랑하중의 진폭과 주기, 보 경간을 매개변수로 한 증폭계수의 추이를 분석하였으며 보 모멘트의 증폭계수는 특정회귀방정식으로 나타내었다.

모바일 3차원 그래픽 연산을 위한 제곱근 및 역제곱근 연산기 구조 및 설계 (Design of Square Root and Inverse Square Root Arithmetic Units for Mobile 3D Graphic Processing)

  • 이찬호
    • 대한전자공학회논문지SD
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    • 제46권3호
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    • pp.20-25
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    • 2009
  • 본 논문에서는 모바일 환경 기반의 3차원 그래픽 연산을 위한 조명처리 엔진 및 쉐이더 프로세서에 사용 가능한 제곱근과 역제곱근 연산기의 구조를 제안한다. 제안하는 구조는 Taylor 전개식을 기반으로 하여 참조 테이블 및 보정 유닛으로 구성되어 있어 참조 테이블의 크기를 줄였다. 연산 결과는 IEEE-754 표준의 단정도 32 bit 부동소수점 형식과 모바일 환경을 위하여 이를 축소한 24 bit 부동소수점 형식에 대해 OpenGL 1.x ES 에서 요구하는 $10^{-5}$의 정확도를 거의 만족한다. 제안된 구조에 따라 설계된 제곱근 및 역제곱근 연산기는 Verilog-HDL을 사용하여 설계되었으며 파라미터 변경을 통하여 24 bit와 32 bit 연산이 가능하도록 합성이 가능하고 1사이클의 잠복기를 갖는다. 설계된 연산기들의 동작은 FPGA를 이용한 검증시스템을 통하여 검증하였다.

부유식 해양플랜트 다점 계류라인의 피로손상모델 비교 (Comparison of Fatigue Damage Models of Spread Mooring Line for Floating Type Offshore Plant)

  • 박준범;김국현;김경수;고대은
    • 한국해양공학회지
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    • 제27권5호
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    • pp.63-69
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    • 2013
  • The mooring lines of a floating type offshore plant are known to show wide banded and bimodal responses. These phenomena come from a combination of low and high frequency random load components, which are derived from the drift-restoring motion characteristic and wind- sea, respectively. In this study, fatigue models were applied to predict the fatigue damage of mooring lines under those loads, and the result were compared. For this purpose, seven different fatigue damage prediction models were reviewed, including mathematical formula. A FPSO (floating, production, storage, and offloading) with a $4{\times}4$ spread catenary mooring system was selected as a numerical model, which was already installed at an offshore area of West Africa. Four load cases with different combinations of wave and wind spectra were considered, and the fatigue damage to each mooring line was estimated. The rain flow fatigue damage for the time process of the mooring tension response was compared with the results estimated by all the fatigue damage prediction models. The results showed that both Benasciutti-Tovo and JB models could most accurately predict wide banded bimodal fatigue damage to a mooring system.

Static and dynamic mooring analysis - Stability of floating production storage and offloading (FPSO) risers for extreme environmental conditions

  • Rho, Yu-Ho;Kim, Kookhyun;Jo, Chul-Hee;Kim, Do-Youb
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제5권2호
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    • pp.179-187
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    • 2013
  • Floating production storage and offloading (FPSO) facilities are used at most of the offshore oil fields worldwide. FPSO usage is expected to grow as oil fields move to deeper water, thus requiring the reliability and stability of mooring wires and risers in extreme environmental conditions. Except for the case of predictable attack angles of external loadings, FPSO facilities with turret single point mooring (SPM) systems are in general use. There are two types of turret systems: permanent systems and disconnectable turret mooring systems. Extreme environment criteria for permanent moorings are usually based on a 100-year return period event. It is common to use two or three environments including the 100-year wave with associated wind and current, and the 100-year wind with associated waves and current. When fitted with a disconnectable turret mooring system, FPSOs can be used in areas where it is desirable to remove the production unit from the field temporarily to prevent exposure to extreme events such as cyclones or large icebergs. Static and dynamic mooring analyses were performed to evaluate the stability of a spider buoy after disconnection from a turret during cyclone environmental conditions.

Flapping Foil을 적용한 위치유지시스템 개발을 위한 운동시험 (Feasibility Study for Development of New Stationkeeping System)

  • 유영재;심우림;;김동주;신현경
    • 한국해양공학회지
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    • 제33권2호
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    • pp.189-195
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    • 2019
  • In this study, experiments with a floater using flapping foils were performed to develop a new station keeping system that can maintain its position in waves without mooring lines. The foils applied to this system generate thrust using wave energy. In this experiment, the motion of the floater was analyzed in three different wave periods. Sixteen foils were attached to the cylindrical floater. The thrust of each foil was controlled by changing its azimuth angle, and three cases were compared. Based on the previous data, we made more precise measurements and found an optimal model for stationkeeping under each wave condition. We verified the potential of this new stationkeeping system using flapping foils, and conclusions were drawn from the results.

연성된 과대 경사 각도를 고려한 부유식 구조물의 비선형 유체정역학 힘과 자세 (Computation of Nonlinear Hydrostatic Force and Position of a Floating Structure Considering the Coupled Large Inclined Angles)

  • 차주환;구남국;박광필
    • 한국CDE학회논문집
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    • 제21권1호
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    • pp.90-98
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    • 2016
  • When ships and offshore plants are flooded or the floating crane is equipped with a heavy object, these floating structures are excessively inclined. In this case, immersion, heel, and trim affecting the hydrostatic restoration performance are very large and are coupled each other. In this paper, in order to calculate a static equilibrium position of floating structures with excessive inclination, the nonlinear governing equations were constructed by sequential linearization. In the governing equation, the immersion, heel, and trim are fully coupled, and the equations are represented using a plane area, a primary moment, and a moment of inertia of the water plane area. Therefore, it is possible to calculate the additional factor related the water plane area for estimating stability. Position and orientation of the floating structure are obtained by iterative calculation. The calculated results are compared with the previous studies in the aspect to the performance and the accuracy.

중량물의 동적 거동에 미치는 크레인 붐(boom)의 탄성 영향 분석 (Analysis of an Elastic Boom Effect on the Dynamic Response of a Cargo)

  • 박광필;차주환;이규열
    • 대한조선학회논문집
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    • 제47권3호
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    • pp.421-429
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    • 2010
  • In this paper, in order to analyze the dynamic response of a floating crane when it lifts a heavy cargo, the boom of the floating crane is considered as an elastic beam. The boom is divided into elements based on finite element formulation and the floating frame of reference formulation and nodal coordinates are employed to model the boom as a flexible body. As an extension of the previous study, in order to consider spatial motion in waves, the coupled equations of motions of the 6 degree of freedom (DOF) floating crane and 6 DOF cargo are developed based on the flexible multibody system dynamics. The 3 dimensional deformation of the elastic boom is considered with 18 DOF. The dynamic simulation of the floating crane and the cargo is performed under regular wave conditions with various cargo weights. Finally, the effects of the elastic boom on lifting cargo are discussed by comparing the simulation results between the elastic boom and a rigid boom.