• 한국항해학회지
• /
• 제18권4호
• /
• pp.11-21
• /
• 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.

• 한국시뮬레이션학회논문지
• /
• 제19권3호
• /
• pp.17-25
• /
• 2010

선박 조종 시뮬레이션을 구성하는 기동 모델은 대상 선박의 동역학적인 특성을 현실에 가깝게 구현해야 하며, 신속한 계산 및 결과 처리가 가능하여야 한다. 다중 선박을 대상으로 하는 실시간 조종 시뮬레이션에서는 계산 시간 단축을 위해 일반적으로 선회각이나 선회율, 또는 전진 속도에 대한 1차 미분방정식 모델을 사용하여 선박의 움직임을 구현하게 된다. 본 논문에서는 대상 선박의 선회 시험 정보가 주어져 있을 경우 이를 이용한 선박의 단순 기동 모델링 및 계수 추정법을 제안하였다. 전진속도가 일정한 모델과 전진 속도의 변화를 고려한 모델의 계수 추정법을 수학적으로 전개하였으며, 실선 선회 시험 자료를 이용하여 제안된 모델의 유용성을 검증하였다.

• 한국해양공학회지
• /
• 제37권4호
• /
• pp.129-136
• /
• 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.

• 대한조선학회논문집
• /
• 제47권6호
• /
• pp.776-781
• /
• 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.

• 한국항해항만학회지
• /
• 제29권3호
• /
• pp.189-194
• /
• 2005

선박이라는 거대한 물체를 항만 또는 조선소내의 안벽에 접안하거나 이로부터 이안시키는 작업은 도선사나 도크마스터의 고유한 업무로서 상당한 집중력과 고도의 위험성을 내포하고 있다. 이와 같은 접이안 작업 시에는 예선의 사용량이 많아지고, 본선이 저속으로 움직이므로 외력의 영향을 크게 받는다. 본 연구에서는 외력의 영향 특히 강풍 하에서 주로 예선을 이용하여 접이안 조종 작업을 수행할 수 있는 2차원 가상시스템은 구축하였다. 또한 조종위험도를 평가할 수 있는 객관적인 기준을 제안하고 이를 위해 시뮬레이션 실험은 수행하였다. 이 가상시스템을 이용하여 접이안 조종 작업을 수행한 결과 운항자가 주관적으로 체감한 위험의 정도를 수치화하여 표현한 주관적 평가와 조종운동과 관련된 주요 파라미터에 관련된 객관적인 지수와의 상관관계를 분석하여 조종위험도의 평가 기법에 대해 논의한다.

• Journal of Ship and Ocean Technology
• /
• 제11권1호
• /
• pp.11-24
• /
• 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.

• 대한조선학회논문집
• /
• 제46권2호
• /
• pp.114-126
• /
• 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.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2002년도 추계학술발표회
• /
• pp.111-124
• /
• 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
• /
• 제13권1호
• /
• pp.466-477
• /
• 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.

• 대한조선학회논문집
• /
• 제57권6호
• /
• pp.331-344
• /
• 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.