• Journal of the Korean Institute of Navigation
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• v.23 no.4
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• pp.43-61
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• 1999

To ensure ship's safety and preserve the marine environment from ship, IMO(International Maritime Organization) has been making much efforts. Nevertheless there are still many possibilities threatening ship's safety and the marine environment. Many vessels navigate at sea in lack of standard required by the International Convention relevant to ship's safety and the protection of marine environment. Even though the administration is responsible for perfect and continuous control for safety of ship, it cannot has jurisdiction over ships hoist its flag reasonably at all times. So the Port State has strengthened the Port State Control(PSC) activity as one step of eliminating sub-standard vessels. In the light of the fact that mentioned above, this study deals with PSC activity in Korea and port of Pusan. Total 582 ships, inspected in port of Pusan from 1st January 1998 to 30th September 1999, were analyzed in various aspect and extracted results as follows : \circled1 The inspection rate in Korea was much lower than the other states taking part in Tokyo MOU, \circled2 For flag state, the ships belong to flag of convenience(FOC) had much more deficiencies than non-convenience flag ships, \circled3 For ship type, 39 number of general dry cargo ship were detained at Pusan with serious deficiencies, \circled4 For deficiency item, the items such as life saving appliances, safety in general, navigation, load lines and fire-fighting appliances were occupied over 71.7% of total number of deficiencies, \circled5 In Asia-Pacific region, Korea was one of flags with detention percentages exceeding 3-year(1996~1998) rolling average detention percentage. Average detention rate of Korean vessels was 6.73% which was over 0.24% of average detention rate(6.49%) in Asia-Pacific region. These results may reflect to improve the performance of PSC inspection for foreign vessels and are useful for preparing PSC inspection for ocean-going ships registered in Korea.

• 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.

• International Journal of Internet, Broadcasting and Communication
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• v.8 no.1
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• pp.53-63
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• 2016

This paper applies WiMedia UWB network into a wireless ship area network (WSAN) so as to support high-quality multimedia services on board and reliable instrument control information as well, since the need for mixed high-quality video traffic and shipboard control data traffic is essential for a high-cost valued digital ship. Thus, in this paper, prioritized contention access (PCA) and distributed reservation protocol (DRP) based on WiMedia UWB (ECMA-368) MAC protocols are combined and proposed to such mixed traffic environment, by varying the portions of superframe according to traffic type. It is shown that the proposed WiMedia UWB MAC protocol can provide reliable mixed video and shipboard control data traffic as well.

• Journal of the Korean Institute of Navigation
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• v.5 no.2
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• pp.59-88
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• 1981

Many studies have been done in the field of fuzzy logic theory, but it's application is not so much, and particularly, there isn't any application to the ship's steering system, until now. This paper is to survey the effect of application of fuzzy logic control to the ship's steering system. The controller is made up of a set of Linguistic Control Rules which are conditional linguistic statements connecting the inputs and the output, and take the inputs derived from the errors, that is, deviation angle and it's angular velocity. These two variables together give information about the state of the steering system, and the Linguistic Control Rules are implemented on the digital computer. The characteristics of this system were investigated through the computer simulation and satisfactory results compared with that of the conventional PD controller were obtained.

• Journal of Navigation and Port Research
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• v.28 no.7
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• pp.609-617
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• 2004

The total tug capacity needed for berthing/unberthing operations of a ship may vary depending on the ship's type, size, loading conditions, and environmental circumstances. Traditionally, total tug capacity is determined based on the local guidelines of port authorities or on the rule of thumb. However, the social demands for the enhancement of ship safety at harbor and the economical demands for the cost-effectiveness of tug usage makes it necessary for port authorities to develop more reasonable and detailed guidelines on tug usage which takes various conditions into account. In this paper, the method to estimate the optimum tug capacity of VLCC is suggested by considering various ship conditions such as its size, loading conditions, and environmental circumstances including wind, wave, tidal currents, and geographical characteristics of a terminal. This method is applied to the VLCC terminal located in Gwang-Yang harbor of Korea and the results are compared with the local guidelines of the harbor, which shows that there may be a room for the amendment of local guidelines on tug usage.

• Journal of the Korean Society for Marine Environment & Energy
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• v.2 no.1
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• pp.90-101
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• 1999

This paper is concerned with the design of automatic ship maneuvering system including automatic path tracking controller and automatic berthing controller. The optimal control technique is employed to design the automatic path tracking controller, which is based on the linearized equations of ship motion. The numerical example shows that the automatic path tracking controller is capable of tracking the line between way points which are determined by pilot a priori. The decentralized control technique is employed to design the automatic berthing controller. In addition to the automatic path tracking controller, the fuzzy logic controller is used to control the forward speed. The numerical example shows that the automatic berthing controller can be successfully implemented.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.136-138
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• 2008

The output voltage of synchronous generator is regulated constantly by field current control in excitation system. Most of ship generator exciter system uses the thyristor phase controlled rectifier. However this rectifier is difficult to realize that the speed control system because its control period is slower than MOSFET and IGBT type converter. Therefore, this paper deals with PMG(Permanent Magnet Generator) type digital excitation system using MOSFET for ship synchronous generator. The organization of this excitation system is very simple. When the generator is under the short circuit accident, the output voltage becomes zero state and AVR can not operate. Thus generator requires the function for flowing output current through CBS. The performance of the proposed system is evaluated on a 10kVA experimental prototype circuit in place of real ship generator.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2449-2457
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• 1996

This paper presents a design method for autopilot control system in course change to the specified direction based on a robust digital servo controlmelthod incorporating the concept of the annihilator polynormial. The mathematicalmodel of ship turning motion is very complex in the view of practical control because it has time varying parameters, nonlinear and dead time terms. To apply the digital servo control method based on computer control, the model is linearized at an equilibrium point and discretized with appropriate sampling time. The control algorithm was evaluated on the basis of computer simulation for a model ship and the practical experiment was carried out with an image processing method for measurement of ship position in a water tank. The results of overall experiments show that the proposed control method will be one of good way to keep a track plotted in the map.

• Journal of the Korean Institute of Navigation
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• v.14 no.4
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• pp.17-30
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• 1990

Since L.A. Zadeh introduced the theory of fuzzy sets in 1965, E.H. Mamdani applied the theory to the steam engine control in 1974. Since then, scientists have shown a great deal of interests in its application to practical problems and the possibility of the application of the theory a more complicate system has been increasing greatly. In the fuzzy control, the qualitative knowledge and intuition that the operators of a system has acquired through their experience can be logically described by the Linguistic Control Rule(LCR). The algorithm of th control is made of the LCR, and th control of an object is performed by processing this algorithm implementing a computer. in this thesis, the fuzzy controller of the ship's steering system is devided into two systems, namely FC1 and FC2, according to their control function. FC1 is for the course keeping steering, wheress FC2 is for the altering of s ship's course. The characteristics of the control system were investigated through the digital computer simulation and the results were compared with those of the conventional steering system. It was found that the fuzzy control was more efficient than the conventional auto pilot system.

• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.53-57
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• 2003

The last goof if the study is to develop a law cost and a readily available Virtual Reality (VR) based Ship Handling Simulator using Personal Computer. This paper mainly describes procedures and methods to control the dynamic motions if the 3D ship object with maneuvering coefficients in a virtual navigation world The creation if virtual navigation world, the mathematical background q a ship control, and the construction of the system are also discussed.