• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.5
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• pp.407-413
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• 2013

This paper deals with the analysis of dynamic characteristics of mooring system of floating-type offshore wind turbine. A spar-type floating structure which consists of a nacelle, a tower and the platform excepting blades, is used to model the floating wind turbine and connect three catenary cables to substructure. The motion of floating structure is simulated when the mooring system is attached using irregular wave Pierson-Moskowitz model. The mooring system is analyzed by changing cable position of floating structure. The dynamic behavior characteristics of mooring system are investigated comparing with cable tension and 6-dof motion of floating structure. These characteristics are much useful to initial design of floating-type structure. From the simulation results, the optimized design parameter that is cable position of connect point of mooring cable can be obtained.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.4
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• pp.18-27
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• 2010

We had designed and constructed floating type photovoltaic energy generation system. In this paper, we present the result of investigations pertaining to the development of links between unit modules of the floating type photovoltaic energy generation system. The link system installed between the unit modules is made of pultruded FRP, tire, and polyethilene synthetic fiber rope. The link system is analized by the finite element method. The floating type photovoltaic energy generation system consisted of unit modules connected by link system is installed successfully at sea site. In addition, we present the modified design of the floating type photovoltaic energy generation system based on the proto type system.

• Current Photovoltaic Research
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• v.1 no.2
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• pp.122-125
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• 2013

The Floating Photovoltaic System was installed on the surface of water. There were some researches in this subject. But there was not many studies with experiment on a high waterproof Floating Photovoltaic modules. The aim of this study was to analyze the performance of the Floating Photovoltaic System. For this experiment, a high waterproof Floating Photovoltaic modules were designed and applied to the module capacity of 10 kW Tracking-Type structure. The experiment results indicated the performance of the daily production is 51.6 kW; the production capacity of Floating Photovoltaic System is expected to be 23% higher than that of the ground-mounted photovoltaic system.

• Structural Engineering and Mechanics
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• v.63 no.1
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• pp.37-46
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• 2017

This paper is concerned with the numerical study on the resonance response of a rigid spar-type floating platform in coupled heave and pitch motion. Spar-type floating platforms, widely used for supporting the offshore structures, offer an economic advantage but those exhibit the dynamically high sensitivity to external excitations due to their shape at the same time. Hence, the investigation of their dynamic responses, particularly at resonance, is prerequisite for the design of spar-type floating platforms which secure the dynamic stability. Spar-type floating platform in 2-D surface wave is assumed to be a rigid body having 2-DOFs, and its coupled dynamic equations are analytically derived using the geometric and kinematic relations. The motion-variance of the metacentric height and the moment of inertia of floating platform are taken into consideration, and the hydrodynamic interaction between the wave and platform motions is reflected into the hydrodynamic force and moment and the frequency-dependent added masses. The coupled nonlinear equations governing the heave and pitch motions are solved by the RK4 method, and the frequency responses are obtained by the digital Fourier transform. Through the numerical experiments to the wave frequency, the resonance responses and the coupling in resonance between heave and pitch motions are investigated in time and frequency domains.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.95-104
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• 2006

A floating-type wave power pump is a device which sends air into water by using wave power. The floating-type wave power pump has the new configuration composed of a curved surface reflection board, a slope, and phase plates. As a result of a water-tank experiment it turned out that the floating-type wave power pump with a curved surface reflection board and a slope raised power and efficiency in the wide wavelength waves. The result of a marine experiment was also preferable. The floating-type wave power pump sends air into the sea by using wave power, so it can be used for the improvement of marine environment. In addition, the floating body constituted of a curved surface reflection board, a slope, and phase plates, is effective as a device to utilize the energy of a wave. Therefore, it can be widely used for a wave power generation, pumping up deep seawater.

• Journal of Ocean Engineering and Technology
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• v.26 no.2
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• pp.48-57
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• 2012

This paper deals with numerical analyses in the context of estimations of hydrodynamic motions and dynamic loads for a floating type offshore platform using some exclusive simulation code such as code for the simulation of a floating type of offshore crane based on multi-body dynamics, along with the commercial code AQWA. Verifications of numerical models are carried out by comparing the RAO results from the simulation code. In the verification analyses, hydrodynamic motions are examined in the frequency domain for the floating type offshore platform according to the mooring lines. Both the hydrodynamic motions and dynamic loads are estimated for floating type offshore platforms equipped with the catenary type and taut mooring lines. A review and comparison are carried out for the numerically estimated results. The structural safety of the connection parts in an offshore structure such as a floating type offshore platform is one of the most important design criteria in view of fatigue life. The dynamic loads in the connecting area between a floating type offshore platform and its mooring lines are estimated in detail according to variations in the mechanical properties of the mooring lines. The dynamic tension load on the mooring lines is also estimated.

• Journal of Ocean Engineering and Technology
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• v.12 no.2 s.28
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• pp.43-56
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• 1998

A barge-type structure has been recently watched since The Floating Structures Association of Japan proposed the new concept as the most suitable one of floating airports. In this paper, the method, which is based on a combination of a three-dimensional source distribution method and the wave interaction theory is applied to very large floating structure of barge-type. The calculated results show good agreement with the experimental and calculated ones by Yago and remarkable characteristics concerning the hydroelastic behavior of the very large floating structure on the effects of hydrodynamic interactions and choice of body modelling.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.1
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• pp.16-26
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• 2010

In this paper, we present the result of investigations pertaining to the development of the floating type photovoltaic energy generation system. Pultruded FRP has superior mechanical and physical properties compared with those of conventional structural materials. Since the FRP has an excellent corrosion-resistance and high specific strength and stiffness, the FRP material may be highly appreciated for the development of the floating type photovoltaic energy generation system. In the paper, we discussed the development concepts of the floating type photovoltaic energy generation system, briefly. The mechanical properties of the FRP structural member used in the development are investigated through the tensile and compression tests. Test results are used in the finite element analysis and the design of the system. In addition, bolted connections of the members are briefly discussed and the strengths of FRP bolted connections are estimated based on the results of experiments. The experimental results are compared with the finite element analysis results and discussed briefly. The floating type photovoltaic energy generation system is designed, fabricated, and installed successfully in site.

• Wind and Structures
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• v.24 no.4
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• pp.333-350
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• 2017

Differing from the fixed-type, the dynamic motion of floating-type offshore wind turbines is very sensitive to wind and wave excitations. Thus, the sensing and monitoring of its motion is important to evaluate the dynamic responses to the external excitation. In this context, a monitoring system for sensing and processing the wind-induced dynamic motion of spar-type floating offshore wind turbine is developed in this study. It is developed by integrating a 1/00 scale model of 2.5MW spar-type floating offshore wind turbine, water basin equipped with the wind generator, sensing and data acquisition systems, real-time CompactRIO controller and monitoring program. The scale model with the upper rotatable blades is installed within the basin by means of three mooring lines, and its translational and rotational motions are detected by 3-axis inclinometer and accelerometers and gyroscope. The detected motion signals are processed using a real-time controller CompactRIO to calculate the acceleration and tilting angle of nacelle and the attitude of floating platform. The developed monitoring system is demonstrated and validated by measuring and evaluating the time histories and trajectories of nacelle and platform motions for three different wind velocities and for eight different fairlead positions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.610-614
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• 1996

As the run out error and misalignment of ball screw connected directly to guide table largely affect the motion accuracy of guideway, floating coupling that releases the table from screw nut except feed and rotational direction is needed todecrease its influences. The purpose of this study is to propose a practical model floating coupling of ball serew for high precision feeding system. The straightness, dynanic characteristics and micro step response of hydrostatic guideway, mounted with three types of coupling fixed type, leaf spring type and hydrostatic type, are tested and compared. From the resuts of experiments, it is proved that a hydrostatic type floating coupling is superior to other couplings and is available to high precision feeding system with ball screw.