• Journal of the Korean Institute of Navigation
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• v.18 no.4
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• pp.11-21
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• 1994

Final aim of this paper is a study on simulation of automatic steering of a ship in random seas. In order to achieve this aim, we need excitation due to random seas. The excitation may be estimated from energy spectrum of irregular waves and response functions of manoeuvring motion of a ship in regular waves. This paper deals with response functions of manoeuvring motion of a ship in regular waves. We discussed New Strip Method(NSM) of sway-yaw-roll coupled motions in regular waves. NSM is defined in space axes system and that has been used to predict seakeeping performance of a ship in waves. But ship manoeuvring is defined in body fixed axes system. So we cannot use NSM theory itself in predicting manoeuvring performance of a ship in waves. We introduced relationship between space axes system and body fixed axes system. And we developed modified NSM which was defined in body fixed axes system and was able to be used in manoeuvring motion of a ship in waves. We calculated sway and yaw response functions of manoeuvring motion of a bulk carrier in regular waves.

• Journal of the Korea Society for Simulation
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• v.19 no.3
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• pp.17-25
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• 2010

It is necessary for the ship dynamic models to realize ship dynamics and to achieve the real-time analysis in the manoeuvring simulation. Generally, simple dynamic models, such as 1st-order differential equation models of turning angle, turning rate, and forward speed, are used in the manoeuvring simulation for multiple ships. Ship dynamic modeling and parameter estimation methods based on its turning test results are proposed in this paper. Parameter estimation methods for the constant speed model and the speed-changing model are mathematically developed and verified by comparing with turning test results of a real ship.

• Journal of Ocean Engineering and Technology
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• v.37 no.4
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• pp.129-136
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• 2023

To evaluate manoeuvring performance of merchant ships, the mathematical modeling group (MMG) or computational fluid dynamics (CFD) simulations are used. However, it is difficult to use the MMG to evaluate the manoeuvring performance of fishing vessels, thus research using CFD simulations is necessary. Also, since the course-changing and turning ability is crucial in fishing operations, a rudder design suitable for fishing vessels is necessary. This study designs a rudder using National Advisory Committee for Aeronautics (NACA) airfoil sections and evaluates its manoeuvring performance. A CFD model is used to evaluate the manoeuvring performance of the fishing vessel, and turning and zig-zag tests are conducted. The effectiveness of using CFD simulations based on Reynolds averaged Navier-Stokes equations to assess the manoeuvring performance of fishing vessels was validated. No significant difference was found in the manoeuvring performance for hull forms and rudder designs for course-changing ability. However, the original hull form showed superior turning performance. Among five rudders with varying aspect ratios and shapes, the rudder with 5.5% aspect ratio had the best turning performance. Regarding the rudder design for fishing vessels, NACA airfoil was employed, and a rudder aspect ratio of 5.5% based on the immersed hull side area is recommended.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.6
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• pp.776-781
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• 2010

In the ship-handling simulator, it is important for a ship manoeuvring model to represent the dynamic characteristic of a ship and to be simple for reducing calculation time. Especially, even if principal dimensions of a ship are given in initial design stage, or manoeuvring test data are only given by model or real ship's trials, simulations are often needed to check the manoeuvrability of a ship. In this paper, a simple manoeuvring model based on turning test data of a ship is mathematically developed. And the simulation results are verified by comparing with turning test results of a real ship.

• Journal of Navigation and Port Research
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• v.29 no.3 s.99
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• pp.189-194
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• 2005

The berthing/deberthing manoeuvring operation is the peculiar work owned to the marine pilot and the dock master. So, in the port or the shipyard, the berthing/deberthing manoeuvring operation requires considerable concentration and bears dangerousness. In that situation, a tug utilization is getting increased and the external forces have an effect on the own ship because of moving with low advance speed. In this study, we constructed the 2-dimensional virtual ship manoeuvring simulator system with which we can carry out the berthing/deberthing manoeuvring operation by using tugs in the external forces such as strong wind. And then, we propose the objective indexes by which the degree of manoeuvring difficulty evaluated. Using the present system, we carry out manoeuvring simulation experiment in order to grasp correlation between the objective indexes proposed here and the def{ree of manoeuvring difficulty felt by operator. Lastly, we discuss the evaluation technique of manoeuvring difficulty.

• Journal of Ship and Ocean Technology
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• v.11 no.1
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• pp.11-24
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• 2007

Better prediction of a ship's manouevrabilty in initial design stage is becoming more, important as IMO manoeuvring criteria has been activated in the year of 2004. In the present study, in order to obtain more exact and reliable results for ship manoeuvrability in the initial design stage, numerical simulation is carried out by use of RANS equation based calculation of hydrodynamic forces exerted upon the ship hull. Other forces such as rudder force and propeller force are estimated by one of the empirical models recommended by MMG Group. Calculated hydrodynamic force coefficients are compared with those obtained by empirical models. Standard manoeuvring simulations such as turning circle and zig-zag are also carried out for a medium size Product Carrier and the results are compared with those of pure empirical models and manoeuvring sea trial. Generally good qualitative agreement is obtained in hydrodynamic forces due to steady oblique motion and steady turning motion between the results of CFD calculation and those of MMG model, which is based on empirical formulas. The results of standard manoeuvring simulation also show good agreement with sea trial results.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.2
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• pp.114-126
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• 2009

The authors adopt the Unmanned Undersea Vehicle(UUV), which has taken the shape of manta(Sohn et al. 2006). They call here it Manta-type Unmanned Undersea Test Vehicle(MUUTV). MUUTV is based on the same design concept as UUV called Manta Test Vehicle, which was originally built and operated by the Naval Undersea Warfare Center(Lisiewicz and French 2000, Sirmalis et al. 2001). In order to evaluate manoeuvring motion characteristics of MUUTV, numerical simulation technique has been utilized. Previous mathematical model on manoeuvring motion of MUUTV(Sohn et al. 2006) is basically adopted. Result of static experiment carried out in circulating water channel and a part of NSRDC standard model(Feldman 1979) on rotational mode are supplemented. Some of the hydrodynamic derivatives are obtained from model experiment in circulating water channel and the rest of them are estimated.

• Proceedings of KOSOMES biannual meeting
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• 2002.10a
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• pp.111-124
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• 2002

Ship manoeuvring simulator has been widely utilized for training mariners, for assessing safety, for developing harbour and port, and for designing ships. We discuss a ship manoeuvring simulator which has been newly developed by Korea Maritime University. The simulator consists of simulator bridge and control console. All the computers used in the simulator are connected with one another by UDP or TCP network system. All the instruments are connected with interface computer by signal line which is controlled by RS232 communication protocol, or by voltage controlled A/D board. Next the mathematical model of ship manoeuvring motion in harbour areas, and ship and terrain modeling technique are also briefly discussed. Finally using the simulator an experiment of distance cognition and a simulation example of berthing/deberthing manoeuvre are shown.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.466-477
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• 2021

There are three different well-known methods for predicting the manoeuvrability of ships: (1) free running model test, (2) direct manoeuvring simulation using CFD and (3) system-based manoeuvring simulation. In this paper, the manoeuvrability of the KVLCC2 was estimated using CFD with rigid body motion and body force propeller method. The free running manoeuvre at the different time steps were also simulated. The yaw checking ability and the turning ability of KVLCC2 were predicted using CFD and could have been confirmed that the IMO criteria was satisfied. When the results were compared with the model test and system-based method, the free running simulation showed better agreement to that of the model test. It could also be confirmed that the results vary depending on the time step. Overall, the CFD results using the body force propeller method estimated most accurately the test results.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.6
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• pp.331-344
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• 2020

Ship's hydrodynamic coefficients in manoeuvring equations are generally derived by captive model tests or numerical calculations. Empirical formulas have been also proposed in some previous researches, which were useful for practical predictions of hydrodynamic coefficients of a ship by using main dimensions only. In this study, ship's hydrodynamic coefficients based on empirical formulas were optimized by using its free running test data. Eight manoeuvring performance indices including steady turning radius, reach in zig-zag as well as well-known IMO criteria indices are selected in order to compare simulation results with free runs effectively. Sensitivities of hydrodynamic coefficients on manoeuvring performance indices are analyzed. And hydrodynamic coefficients are tuned within fixed bounds in order of sensitivity so that they are tuned as little as possible. Linear and nonlinear coefficients are successively tuned by using zig-zag and turning performance indices. Trajectories and velocity components by simulations with tuned hydrodynamic coefficients are in good agreements with free running tests. Tuned coefficients are also compared with coefficients by captive model tests or RANS calculations in other previous researches, and the magnitudes and signs of tunes are discussed.