• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.1
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• pp.38-52
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• 2016

This paper describes the nonlinear dynamic motion behavior of a ship equipped with a portable dynamic positioning (DP) control system, under external forces. The waves, current, wind, and drifting forces were considered in the calculations. A self-tuning controller based on a neuro-fuzzy algorithm was used to control the rotation speed of the outboard thrusters for the optimal adjustment of the ship position and heading and for path tracking. Time-domain simulations for ship motion with six degrees of freedom with the DP system were performed using the fourth-order RungeeKutta method. The results showed that the path and heading deviations were within acceptable ranges for the control method used. The portable DP system is a practical alternative for ships lacking professional DP facilities.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.129-137
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• 2008

Hull-Mounted Sonar(HMS) has been the main equipment to detect and track underwater threats like torpedoes and enemy submarines. The HMS has short warming-up time and is employable independently with sea-state and weather condition. But these bad environmental condition and ship maneuvering make ship's roll and pitch. Ship's roll and pitch make unstability of sensor position, then cause degradation of the HMS performance. In this paper, we will show how the unstability influences the HMS performance, propose the 'Beam Stabilization Beamforming Technique' to overcome these phenomenon. And present the effectiveness of proposed technique by comparing with conventional beamforming result.

• Journal of Power System Engineering
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• v.8 no.4
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• pp.17-23
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• 2004

A delivery ship is used to handle the cargo with the crane to/from the ships. The ship is inclined in the direction of a cargo which is hung on a crane. In this case, a arc shaped rail should be in the equilibrium state to get good anti rolling performance. In this study, a device and control algorithm are developed to take accurate and quick equilibrium of the rail. The device is composed of a hinged immovable support and two screw jacks. And the control algorithm demands two controllers. One controller is designed such that the screw jack 1 and 2 follow the position reference signal generated by a tilt sensor. The other controller of two degree of freedom is designed to remove the synchronous error occurred between jack 1 and jack 2. The simulation results show that the desirable control performance is achieved.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1012-1013
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• 2006

Marine technology must advance to meet the needs of a wealthier and more demanding public while at the same time provide greater environmental protection. Pollution noise and vibration is the specific issue being discussed in this paper Noise is of course due to vibration from high speed engines driving generators, entilators, winch and other gear, while underwater noise pollution results from the propellers and the resistance produced by the hull of the ship moving through the water. Vibration is also a factor in potential damage to sensitive electronic gear and metal fatigue. The issue of noise pollution does not cease when a vessel enters her berth and the main engines shut down. There is still the matter of ventilation and other mechanical factors at work to maintain a comfortable, efficient environment. We measured the noise level and vibration displacement in the training ship A-Ra at underway and Berth. The authors analyzed the frequency of noise and maximum vibration displacement in the position.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.4
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• pp.363-368
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• 2005

This paper proposes an LOS(line-of-sight) guidance system of a ship for path following. From the viewpoint of a control configuration, guidance is a special type of compensation algorithm that is placed in front of the controller to accomplish navigational objects. A guidance system generates a reference trajectory for trajectory tracking or path control and decides the desired velocity, position and heading angle. A control system executes commands based on a reliable guidance law during navigation. An LOS vector from the vessel to a point on the path between two way-points in straight-line navigation or a point among turning circle in turning navigation is selected, and then a heading angle is calculated to converge the desired path based on the LOS vector. The LOS guidance law is defined for the straight-line and the turning circle, respectively. The effectiveness of the suggested LOS guidance system is assured through computer simulation.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.180-187
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• 2005

The purpose of this study is to investigate safety consciousness of seafares'. The subjects were 437 seafaes' who took a safety education course in Korea Institute of Maritime and Fisheries Technology. This questionnaire was focused on finding the basic data for prevention of industrial accidents, and getting the public opinions and proposals of seafares'. The results obtained by this study are as follows : The average score of safety consciousness for seafares' were 68.82. Current position level of education navigation area classification of ships, ship size, ship age showed significant difference in statistics(p<0.01). Based on these results, this research pointed out the need to review the training manual, development of educational programs, improvement of facilities to improve safety education of ship, etc.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.1 s.145
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• pp.128-133
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• 2006

This study is focused on the skill to prevent RIB (Rigid Inflatable Boat) from sinking. For better ability to prevent sinking, single hypalon tube is replaced by double TPU (Thermoplastic Polyurethane) tube that is excellent at frictional wear strength and oil-resisting qualities. High buoyant materials are arranged in empty spaces of ship so that ship's spare buoyancy is increased. And for restoration of stable position of ship, the self-righting system is installed. Aluminium alloy is used for increasing hull strength.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.2 s.140
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• pp.98-104
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• 2005

The mathematical models of hydrodynamic force and moment acting on a ship at low speed range should be established differently from the ones at nominal cruising speed range since a ship moves with large drift angle or rotates in a stationary position. We modified widely used Yoshimura's cross flow model in order to apply the system identification method to estimate parameters in the model. The apparatus and the procedure of free running model test were suggested so that the parameters in the model be estimated. The validity of our proposing modified model and test procedure was confirmed by comparison with the results of simulated model test.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.910-917
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• 2020

In fire suppression, continuous delivery of water or foam to the fire source is essential. The present study concerns fire suppression in a ship under sea condition, by introducing reinforcement learning technique to aiming of fire extinguishing nozzle, which works in a ship compartment with six degrees of freedom movement by irregular waves. The physical modeling of the water jet and compartment motion was provided using Unity 3D engine. In the reinforcement learning, the change of the nozzle angle during the scenario was set as the action, while the reward is proportional to the ratio of the water particle delivered to the fire source area. The optimal control of nozzle aiming for continuous delivery of water jet could be derived. Various algorithms of reinforcement learning were tested to select the optimal one, the proximal policy optimization.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.3
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• pp.446-454
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• 2008

Control devices for fire safety systems located in a engine room are to be arranged at a safe position which is easily accessible during a fire. To develop an interpretation for the safe position in engine rooms, calculation and experiments are carried out to determine a correlation between radiant heat and distance from fire in this paper. On the basis of results of this research, the control devices for a main engine are to be installed in the behind side of an obstruction to reduce radiant heat from the fire of the main engine. In case of other control devices, they are also to be provided in the same manner of control devices for the main engine or are to be placed with 5 meters far from fire hazards.