• Journal of Navigation and Port Research
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• v.38 no.1
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• pp.29-37
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• 2014

In this paper, the author consider control system design problem of the surface vessel where any types of floating units are included. To keep their motion/position, the Dynamic Positioning System(DPS) is equipped in. Even though sometimes the thrust systems are installed on them, in general the mooring winch system with the rope/wire is used. Therefore, in this paper we consider a single type mooring winch control problem to keep the vessel's position. For this, we introduce an easy and useful control approach which is based on LQ control theory. In this approach, we introduce the frequency dependent weighting matrices which give the system filters to shape frequency characteristics of the controlled system and guarantee the control performance. Based on this, we will show that the proposed approach works well.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.67-73
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• 2016

This study analyzed the state of the vessels which were using the berth for dangerous goods more than its carrying capacity in the major dangerous cargo handling port of Ulsan in Korea, The result of the analysis showed that a ship which has 3 times more than the maximum berthing capacity was moored at berth. Accordingly, a simulation model for 50,000 DWT berth was built and carried out the mooring safety analysis with 50,000 DWT, 70,000 DWT and 100,000 DWT vessels by mooring assessment program. The evaluation was carried out according to the standard environment presented in OCIMF standards. 50,000 DWT vessel was evaluated to meet the acceptable criteria but, 70,000 DWT and 100,000 DWT vessels exceeded the acceptable limit as per external conditions. Consequently, safe mooring guidelines were suggested and also proposed the building of common 'Mooring safety guideline' for port with assessment of different cases.

• Journal of Advanced Research in Ocean Engineering
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• v.4 no.3
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• pp.115-123
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• 2018

This study was carried using the new approach method to design appropriately the Loading Arm length and the alarm setting according to ship movements on Loading and Unloading marine Berth. The quasi-static mooring analysis was performed to estimate 110,000DWT ship's movements based on environmental conditions such as wind, current and wave. The mooring motion of the ship is very important to determine the loading arm scope, and in this case, the operation condition is performed on the ship without considering the damaged condition of the mooring line because the ship movement in case of damage is larger than intact, and all operations are stopped, the loading arm being released due to control system. From the result of mooring analysis, motion displacements, velocities and accelerations were simulated. They were used to simulate the maximum drifting speeds and distances. The maximum drifting speeds were checked to be satisfied within drifting speed limits. The total maximum drifting distances were simulated with alarm steps of the new approach method. Finally, the loading arm envelopes using the total maximum drifting distances were completed. Therefore, it was confirmed that the new approach method for loading arm envelopes and alarm settings was appropriate from the above results. In the future, it will be necessary to perform the further advanced dynamic mooring analysis instead of the quasi-static mooring analysis and to use the precise computer program analysis for various environments and ship movement conditions.

• Structural Engineering and Mechanics
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• v.61 no.6
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• pp.785-794
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• 2017

This paper is concerned with the comparative numerical and experimental study on the natural behavior and the motion responses of a 1/75 moored scale model of a 2.5 MW spar-type floating offshore wind turbine subject to 1-D regular wave. Heave, pitch and surge motions and the mooring tensions are investigated and compared by numerical and experimental methods. The upper part of wind turbine which is composed of three rotor blades, hub and nacelle is modeled as a lumped mass and three mooring lines are pre-tensioned by means of linear springs. The numerical simulations are carried out by a coupled FEM-cable dynamics code, while the experiments are performed in a wave tank equipped with the specially-designed vision and data acquisition system. Using the both methods, the natural behavior and the motion responses in RAOs are compared and parametrically investigated to the fairlead position, the spring constant and the location of mass center of platform. It is confirmed, from the comparison, that both methods show a good agreement for all the test cases. And, it is observed that the mooring tension is influenced by all three parameters but the platform motion is dominated by the location of mass center. In addition, from the sensitivity analysis of RAOs, the coupling characteristic of platform motions and the sensitivities to the mooring parameters are investigated.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.4
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• pp.300-310
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• 2014

This paper presents a mooring design procedure of a floating offshore wind turbine. The environment data of south offshore area of Jeju collected from Korea Hydrographic and Oceanographic Administration(KHOA) are used for hydrodynamic analyses as environmental conditions. We considered a semi-submersible type floating wind turbine based on Offshore Code Comparison Collaborative Continuation(OC4) DeepCWind platform and National Renewable Energy Laboratory(NREL) 5 MW class wind turbine. Catenary mooring with studless chain is chosen as the mooring system. Important design decisions such as how large the nomial sizes are, how long the mooring lines are, how far the anchor points are located, are demonstrated in detail. Considering ultimate limit state and fatigue limit state based on 100-year return period and 50-year design life, respectively, longterm predictions of breaking strength and fatigue are proposed.

• Journal of Korea Ship Safrty Technology Authority
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• s.23
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• pp.78-97
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• 2007

SPM, which is an abbreviation of Single Point Mooring, also called as SBM(Single Buoy Mooring), is a special buoy besides the quays of the harbor for mooring ships, and is normally a 3m wide cone or cylinder shaped steel drum fixed underwater so it won't move, and is used for mooring cargo-work at outer port by laid-up ships and large crude oil carrier. The work of VLCC SPM mainly is accomplished on the open sea. On the open sea as a result of meteorological condition and the ocean wave influence, When the weather condition is get bed, peremptorily moving to the safety place, because of the gale and the billow, almost happened frequently, the pilot is unable to go on board and the tug is also unable to be used Now because of the bad weather the VLCC SPM moving to the other safety place frequently happened in the ulsan port. the construction of new harbor, it constructed many break water around SPM. So that it is necessary to propose the new standard about how to maneuvering area actually. The standard for handling ranges of the SPM operations was tested and verified by a simulation.. So that it is necessary to propose the new standard about how to maneuvering area actually.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.3
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• pp.313-319
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• 2019

As vessels become larger and competition between ports intensifies, there has been an increase in the number of cases where vessels that exceed the available berths are berthed at the pier. Therefore, there has been an increase in the number of cases in which the bow or stern of a ship is projected and moored. The risk of overhanging berthing is that mooring safety can be compromised because it is not possible to connect the bow and stern mooring line to the ship properly. In addition, collision accidents may occur between moving vessels if the view of a vessel moving in the port is obstructed. Therefore, in this study, the simulation of mooring safety was performed according to the overhanging range in Piers No. 6 and 7 in Ulsan's main port to propose the overhanging limit and operational standards according to each ship. As a result of the assessment, 30,000 DWT bulkers are able to overhang up to 0.75B, and 50,000 DWT bulkers can overhang up to 0.50B. The results of this study are expected to be used as basic data for setting the allowable overhang limit, as well as clear usage criteria for safe unloading operations.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.5
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• pp.364-371
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• 2015

This study is aimed to develop the dynamic analysis technique for a floating aquaculture in a shallow water region under the harsh sea condition. In case of the installation region to transform from a coastal area to the offshore area, the influence of sea bed with sea waves on the mooring lines was announced to be significant by other authors. In this study, the numerical tool was developed to solve dynamic behavior of the floating barge coupled with mooring lines in a shallow zone of the sea considering the influence of sea bed on the floating system.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.162-174
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• 1996

Longline type aquaculture facilities in the open sea are based on the cable-buoy-weight mooring system. For their optimal design it is necessary to estimate tensions along the mooring lines including the attachment points of buoys and weights. However, the dynamic analysis is very complicated due to the nonlinear behaviors of the mooring lines and the effects of wave and current. In this paper, parametric studies for various buoy-weight cases are shown. Finite difference scheme is employed in obtaining eigenfrequencies in the frequency domain. Nonlinear hydrodynamic drag forces are equivalently linearized.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.512-517
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• 2008

The brake system is very important part of the machine working. If the machine can't be stopped, it would be serious accident. It is the same as the ship. The mooring winch brake hold the ship in harbor. But sometimes it appeared the excessive stress and brake lining would be broken. So it is necessary to change the shape of brake system with improve the braking power. This study carried out research on optimum design like as moved the position of link pin or modified the thickness of brake band and lining.