• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.9-17
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• 2019

Interest in renewable energy is rapidly growing around the world. One of the most popular renewable energy sources is solar power, and photovoltaic (PV) systems are the most representative route for generating solar energy. However, with the growing adoption of solar power systems, the demand for land on which to install these systems has increased, which has caused environmental degradation. Recently, floating PV systems have been designed to utilize idle water surface areas of dams, rivers, and oceans. Because floating PV systems will be exposed to harsh environmental stresses, the safety of such systems should be secured before installation. In this study, the structural robustness of a floating PV system was analyzed by conducting numerical simulation to investigate whether the system can withstand harsh environmental stresses, such as wind and wave loads. Additionally, conventional wind and wave load predictions based on the design method and the simulation results were compared. The comparison revealed that the design method overestimated wind and wave loads. The total drag of the PV system was significantly overestimated by the conventional design criteria, which would increase the cost of the mooring system. The simulation offers additional advantages in terms of identifying the robustness of the floating PV system because it considers real-world environmental factors.

• Journal of the Korean Geotechnical Society
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• v.30 no.10
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• pp.33-44
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• 2014

The preliminary design of suction pile as the supporting system for concrete floating structures was performed for the pilot project of the southwest coast area in Korea. Prior to starting design work, site conditions of the area including ground and hydraulic conditions, and a 100-year return period external force were throughly evaluated. The suction pile for mooring of the offshore floating structures has to satisfy the lateral resistance against external force as well as the penetration ability according to the soil conditions such as soil types, shear strengths, effective stresses, and seepage forces. In the design, the required penetration depths, which were stable for lateral resistance, were evaluated with the diameters of cylindrical suction pile as the final installing ones. And the design suction pressures at each penetrating depths, at which sand boiling did not occur, were assessed through the comparison of penetration and penetrationresistance forces. As a result, it was impossible for suction piles with the diameter range of 3.0~5.0 m to penetrate into required penetration depths. On the other hand, suction piles with the diameter range of 6.0 m and 7.0 m satisfied both the horizontal stability and the penetration ability by design suction pressures at the required penetration depths of 8.5 m and 8.0 m, respectively.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.57-62
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• 2006

Busan New Port, under construction aiming for the hub of Northeast Asia and Partly in operation, had damaged up to 48 billion Won due to Typhoon 'maemi' in 2003. The present criteria of domestic harbor design only describes about the critical wave height with respect to the size of vessel for harbor tranquility. The berth operation ratio which represents the annual available berthing days is depending on the efficiency of cargo handling work and this depends on the motion of the moored vessel due to the wave action and the characteristics of cargo gears. The motion of moored vessel might be related not only to the wave height but also to wave period. Furthermore, the berth operation ratio relies on external forces such as currents and winds, including the characteristics of mooring system and the specification of the moored vessel. In this study we only deal with berth operation ratio in normal sea state, considering wave and current by measured data and numerical calculation. Especially we tried to evaluate the berth operation ratio for each berth adopting the variation of dredging and reclamation plan and the change of wave environment during the process of the new port construction. For better understanding and analysis of wave transformation process, we applied the steady state spectral wave model and extended mild-slope wave model to the related site. This study summarizes comparisons of harbor responses predicted by two numerical predictions obtained at Busan New port site. Field and numerical model analysis was conducted for the original port plan and the final corrected plan.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.821-828
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• 2011

This paper developed the algorithm for improving the performance the auto pilot in the autonomous vehicle system consisting of the Track keeping control, the Automatic steering, and the Automatic mooring control. The automatic steering is the control device that could save the voyage distance and cost of fuel by reducing the unnecessary burden of driving due to the continuous artificial navigation, and avoiding the route deviation. During the step of the ship autonomic navigation control, since the wind power or the tidal force could make the ship deviate from the fixed course, the automatic steering calculates the difference between actual sailing line and the set course to keep the ship sailing in the vicinity of intended course. first, we could get the transfer function for the modeling of ship according to the Nomoto model. Considering the maneuverability, we propose it as linear model with only 4 degree of freedoms to present the heading angle response to the input of rudder angle. In this paper, the model of ship is derived from the simplified Nomoto model. Since the proposed model considers the maximum angle and rudder rate of the ship auto pilot and also designs the Fuzzy controller based on existing PID controller, the performance of the steering machine is well improved.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.485-490
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• 2007

The purpose in having a control rod on a buoy system is to control the motion of it. The system may be composed entirely of a single circular cylinder and a long mooring anchor cable. A control rod has one function to perform in meeting its purpose, and that is to develop a control force in consequence of its orientation and movement relative to the water. The forces and moments generated as a result of the effects of mutual interference. then determine the stability characteristics of the body. In this paper, the study of control-rod-attached buoy's 2-dimensional section was accomplished. model tests and numerical simulations had been carried out with different diameters of control rods. and varying the Reynolds number $Re=5,000{\sim}25,000$ based on the cylinder diameter(D=50mm) to predict the performance of the body and the 2 frame particle tracking method Iud been used to obtain the velocity distribution in the flow field. 50mm circular cylinder Iud been used during the whole experiments and measured results had been compared with each other.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.801-804
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• 2003

The autopilot system of vessel is proposed to take service safety sorority, to elevate service efficiency, to decrease labor and to improve working environment. Ultimate purpose of it is to minimize the number of crew by guaranteeing economical efficiency of shipping service. Recently, the research is being achieving to compensate various nonlinear parameters of vessel and apply it is course keeping control, track keeping control, roll-rudder stabilization, dynamic ship positioning and automatic mooring control etc. using optimizing control technique. Relation between rudder angle controlled by steering machine of vessel and ship-heading angle, and load condition of ship are nonlinear, which affect various parameters of shipping service. The speed and direction of waves, velocity and quantity of wind, which also cause the non-linearity of it. Therefore the autopilot system of ship requires the robust control algorithm can overcome various non-linearity. On this paper, we design the autopilot system of ship, which overcome nonlinear parameters and disturbance of it using Fuzzy Algorithm, evaluate the proposed algorithm and its excellence through simulation

• Proceedings of KOSOMES biannual meeting
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• 2007.05a
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• pp.169-174
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• 2007

The purpose in having a control rod an a buoy system is to control the motion of it. The system may be composed entirely af a single circular cylinder finder and a lang mooring anchor cable. A control rod has one function to perform in meeting its purpose, and that is to develop a control force in consequence of its orientation and movement relative to the water. The forces and moments generated as a result of the effects of mutual interference, then determine the stability characteristics of the body. In this paper, the study of control-rod-attached buoy's 2-dimensional section was accomplished. model tests and numerical simulations had been carried out with different diameters of control rods. and varying the Reynolds number $Re=5,000{\sim}25,000$ based an the cylinder diameter(D=50mm) to. predict the performance af the body and the 2 frame particle tracking method had been used to obtain the velocity distribution in the flaw field 50mm circular cylinder had been used during the whale experiments and measured results had been compared with each other.

• Ocean Systems Engineering
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• v.13 no.4
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• pp.349-365
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• 2023

Targeting a floating wave and offshore wind hybrid power generation system (FWWHybrid) designed in the Republic of Korea, this study examines the impact of the interaction, with multiple wave energy converters (WECs) placed on the platform, on platform motion. To investigate how the motion of WECs affects the behavior of the FWWHybrid platform, it was numerically compared with a scenario involving a 'single-body' system, where multiple WECs are constrained to the platform. In the case of FWWHybrid, because the platform and multiple WECs move in response to waves simultaneously as a 'multi-body' system, hydrodynamic interactions between these entities come into play. Additionally, the power take-off (PTO) mechanism between the platform and individual WECs is introduced for power production. First, the hydrostatic/dynamic coefficients required for numerical analysis were calculated in the frequency domain and then used in the time domain analysis. These simulations are performed using the extended HARP/CHARM3D code developed from previous studies. By conducting regular wave simulations, the response amplitude operator (RAO) for the platform of both single-body and multi-body scenarios was derived and subsequently compared. Next, to ascertain the difference in response in the real sea environment, this study also includes an analysis of irregular waves. As the floating body maintains its position through connection to a catenary mooring line, the impact of the slowly varying wave drift load cannot be disregarded. To assess the influence of the 2^nd-order wave exciting load, irregular wave simulations were conducted, dividing them into cases where it was not considered and cases where it was included. The analysis of multi-degree-of-freedom behavior confirmed that the action of multiple WECs had a substantial impact on the platform's response.

• Journal of Navigation and Port Research
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• v.29 no.7
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• pp.641-646
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• 2005

In cargo-working, it unavoidably happens that the quay crane slip along the rail and the container move from side to side. Especially, they involve a lot of risk in bad weather. The rail clamp is a mooring device to prevent that the quay crane slips along the rail due to bad weather or the wind blast while the quay crane do the cargo-working And it will play a greater role in port container terminal integration and automation To design the wedge type rail clamp, it is very important to determine the wedge angle. In this study, we expect that the design wind speed of the quay crane will change over 16m/s. Assuming that the design wind speed is 40m/s, we determined the proper wedge angle of the wedge type rail clamp for the 50ton class quay crane.

• Journal of Ocean Engineering and Technology
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• v.17 no.2
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• pp.72-76
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• 2003

This paper presents the design concept and operation results of float-off for FSO (340,000 DWT Class, ELF AMENAM KPONO Project) built on the ground, without dry dock facilities. It was the first attempt to build FSO, completely, on the ground and launch it using DBU (Double Barge Unit, which was connected by rigid frame structure.) The major characteristics of FSO, which are similar to general VLCC type hull, including topside structure, weigh 51,000 metric ton. In order to have sufficient stability during the deck immersion of DBU, while passing through a minimum water plane area zone, proper trim control was completed with LMC (Load Master Computer). The major features of the monitoring system include calculation for transverse bending moment, shear force, local strength check of each connector, based on component stress, and deformation check during the load-out and float-off. Another major concern during the operation was to avoid damages at the bottom and sides of FSO, due to motion & movement after free-floating; therefore, adequate clearances between DBU and FSO were to be provided, and guide posts were installed to prevent side damage of the DBU casings. This paper also presents various measures that indecate the connector bending moment, damage stability analysis, and mooring of DBU during float off.