• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.577-583
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• 2012

Structures floating in the ocean experience various kinds of external loads, among which wave load is considered as determining factor in structural design. Its relative size compared with wavelength may be used to classify whether the structure is relatively small or large. Traditionally, the small structures are assumed to have little diffraction and the wave loads on large structure are usually calculated by only considering inertia force according to diffraction. In this paper, rectangular floating structures usually used in the ocean, river, and lake are used to find the relationship between hydrodynamic forces and its structural response.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.10
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• pp.1062-1067
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• 2015

Floating architecture is a type of building that is geographically located on a sea or a river. It floats under the influence of buoyancy, and does not have an engine for moving it. Korea is a peninsula surrounded by sea except on the north side, so floating architectures have been mainly focused on two points: solving the issue of small territory and providing various leisure & cultural spaces. Floating architectures are expected to save energy effectively, if they use sea water heat, which is known to be clean energy with infinite reserves. To use sea water heat as the heat source and/or heat sink, this study proposes a model in which a sea water heat exchanger is embedded in the concrete structure in the lower part of the floating architecture that is submerged under the sea. Based on the results of performance evaluations of the sea water heat exchanger using CFD (computational fluid dynamics) analysis and mock-up experiments under various conditions, it is found out that the temperature difference between the inlet and outlet of the heat exchanger is in the range of $3.06{\sim}9.57^{\circ}C$, and that the quantity of heat transfer measured is in the range of 3,812~7,180 W. The CFD evaluation results shows a difference of 5% with respect to the results of mock-up experiment.

• Korean Journal of Computational Design and Engineering
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• v.19 no.1
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• pp.1-11
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• 2014

In the initial design stage, the technology for estimating and managing the weight of a floating offshore structure, such as a FPSO (Floating, Production, Storage, and Off-loading unit) and an offshore wind turbine, has a close relationship with the basic performance and the price of the structure. In this study, using the genetic programming (GP), being used a lot in the approximate estimating model and etc., the weight estimation model of the floating offshore structure was studied. For this purpose, various data for estimating the weight of the floating offshore structure were collected through the literature survey, and then the genetic programming method for developing the weight estimation model was studied and implemented. Finally, to examine the applicability of the developed model, it was applied to examples of the weight estimation of a FPSO topsides and an offshore wind turbine. As a result, it was shown that the developed model can be applied the weight estimation process of the floating offshore structure at the early design stage.

• Korean Journal of Computational Design and Engineering
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• v.18 no.6
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• pp.439-450
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• 2013

In the case of a floating offshore structure such as FPSO(Floating, Production, Storage, and Offloading unit), many equipment should be installed in the limited space, as compared with an onshore structure. Recently, the requirement for an optimal layout method of the structure has been raised. Thus, a layout method of the floating offshore structure was proposed in this study. First, an optimization problem for layout design was mathematically formulated, and then an optimization algorithm was implemented based on the genetic algorithm in order to solve it. To evaluate the applicability of the proposed method, it was applied to examples ofFPSO topsides and an offshore wind turbine. As a result, it was shown that the proposed method can be applied to layout design of the floating offshore structure.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.219-221
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• 2014

The objective of this paper is to simulate the dynamic behavior of a floating structure model, using image processing and close-range photogrammetry, instead of the contact sensors. Previously, the movement of structure was presented through the exterior orientation estimation of a single camera by space resection. The inverse resection yields the 6 orientation parameters of the floating structure, with respect to the camera coordinate system. The single camera solution is of interest in applications characterized by restriction in term of costs, unfavorable observation conditions, or synchronization demands when using multiple cameras. This article discusses the theoretical determinations of camera exterior orientation based on Direct Linear Transformation and photogrammetric resection using least squares adjustment. The proposed method was used to monitor the motion of a floating model. The results of six degrees of freedom (6-DOF) by inverse resection show that the appropriate initial values by DLT can be effectually applied in least squares adjustment, to obtain the precision of exterior orientation parameters. Additionally, a comparison between the close-range photogrammetry and total station results was feasibly verified. Therefore, the proposed method can be considered as an efficient solution to simulating the movement of floating structure.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.1
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• pp.37-44
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• 2013

This study is about the connector of the floating platform in order to ensure safety due to various climate changes. The purpose of this study is to recommend the connector model of floating platform based on concrete structures after reviewing the literatures related in establishing floating structure in case of various climate changes in domestic coast. This study introduces the concept generation, existing model, detailed design and evaluation including current and future development of the technologies of marina floating platform connector based on concrete structures. The results from the research show that the analysed connector design (Rigid Pontoon Connector) provides a highly efficient and practical solution to facilitate connection of stable floating platform.

• Journal of Ocean Engineering and Technology
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• v.26 no.1
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• pp.70-77
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• 2012

In this study, a numerical analysis of offshore installation using a floating crane with heave compensator is carried out in time domain. The motion analysis of crane vessels is based on floating body dynamics using convolution integral and the crane wire is treated as simple spring. The lifted structure is assumed as a rigid body with 3 degree-of-freedom translational motion. The heave compensator is numerically modelled by the generalized spring-damper system. Firstly, forced motion simulations of crane wire system are carried out to figure out the basic principle of heave compensator. The transfer function of crane wire system is obtained and effective wave period of heave compensator are found. Then, coupled analysis of crane vessel, crane wire, and lifted structure are performed in regular and irregular sea conditions. Two different crane vessels and two lifted structures (suction pile and manifold) are considered in this study. Through a series of numerical calculations, the effective zone of heave compensator is investigated with respect to wave period and crane wire length.

• Korean Journal of Computational Design and Engineering
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• v.21 no.1
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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.

• Structural Engineering and Mechanics
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• v.83 no.1
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• pp.53-66
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• 2022

The main objective of the present research was investigating the effects of a floating wave barrier installed in front of an offshore jacket structure on the wave height, base shear, and overturning moment. A jacket model with the height of 4.55 m was fabricated and tested in the 402 m-long wave flume of NIMALA marine laboratory. The jacket was tested at the water depth of 4 m subjected to the random waves with a JONSWAP energy spectrum. Three input wave heights were chosen for the tests: 20 cm, 23 cm, and 28 cm. Two different cross sections with the same area were selected for the wave barrier: square and rhombus. Results showed that the average decrease in the jacket's base shear due to the presence of a floating wave barrier with square and rhombus cross section was 24.67% and 34.29%, respectively. The use of wave barriers with square and rhombus cross sections also resulted in 19.78% and 33.11% decrease in the jacket's overturning moment, respectively. Hence, it can be concluded that a floating wave barrier can significantly reduce the base shear and overturning moment in an offshore jacket structure; and a rhombus cross section is more effective than an equivalent square section.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.81-89
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• 2009

Performance tests on the 3-Dimensional Flow-Structure-Interactions-Measurement System(FSIMS) have been carried out. Experimental data obtained by the FSIMS on a floating cylinder have been used to generate a set of artificial images. Comparisons between the data obtained by the use of the artificial images and those original experimental data have been made. Another set of artificial images have also been generated based on theoretically modulated sinusoidal motions, and comparisons between the data obtained by the use of these artificial images and the theoretical ones have been carried out. It has been verified that the FSIMS has a measurement uncertainty of 0.04-0.06mm/frame for velocity vectors and 0.002-0.01mm for the cylinder's positions.