• 대한조선학회논문집
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• 제42권2호
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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.

• 대한조선학회논문집
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• 제59권5호
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• pp.288-295
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• 2022

In this study, the force and moment acting on a Joubert BB2 submarine model at depths near the free surface were measured through a captive model test with the scale ratio of 1/15. Based on the experiment, the pitch moment and heave force due to the "Tail suction effect", including the change in surge force with depth near the free surface, were quantitatively analyzed. The change of force and moment according to the relative position of the sail and the free surface was reviewed with the free surface waves generated for each depths. As a result, the angle of attack of the hull to counteract the pitch moment induced by the tail suction effect was derived. The effect of the hydrostatic moment component according to the angle of attack on the equilibrium of pitch moment was also taken into account. The control plane performance tests for the X-type rudder and sail plane were conducted in snorkel and surface depth conditions to figure out the control plane angles for the neutral level flight of the submarine at near free surface. The results of this study are expected to be used as a reference data for the neutral level flight of the submarine at near free surface operation in the free running model test as well as numerical studies.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.585-598
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• 2021

The course-keeping stability of a high speed planing boat should be considered at the design stage for its safe operations. The shape of waterjet intake plane is one of important design parameters of a waterjet propelled planing boat. That has significant influences on the stern flow patterns and pressure distributions. In this study, the effects of the waterjet intake shapes of planing boats on the course-keeping stabilities are investigated. Two kinds of designed planing boats have the same dimensions, but there are differences in waterjet intake plane shapes. Captive and free-running model tests, Computational Fluid Dynamics (CFD) analyses are carried out in order to estimate their hydrodynamic performances including course-keeping stabilities. The results show that the flat and wide waterjet intake plane of the initially designed boat makes the course-keeping stability worse. The waterjet intake shape is redesigned to improve the course-keeping stability. The improved performances are confirmed by free-running model tests and full-scale trials.

• 대한조선학회논문집
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• 제46권3호
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• pp.259-267
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• 2009

Recently, ship maneuverability has been very important issue due to accidents of frequent occurrence at sea. IMO standards for ship maneuverability were applied from January 1, 2004. In this study, maneuverability model tests were considered through a 2m-class KVLCC1 in the Ocean Engineering Wide Tank at University of Ulsan(UOU). Circular Motion Test(CMT) was performed to obtain the maneuvering coefficients by using X-Y Carriage. The trajectories simulated using the coefficients are compared with those of PMM test and free running test.

• 한국기계기술학회지
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• 제13권4호
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• pp.109-115
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• 2011

The ice tank is important facility to check the performance of the ship and offshore in ice condition before the construction. MOERI(Maritime & Ocean Engineering Research Institute) constructed ice model basin on the end of 2010. The ice technology to know the phenomena of ice near the ship and to estimate power of the ship in model scale is the main characteristic of the ice model basin. To achieve this goal in one ice sheet, making of test plan and feasibility check of test possibility have to review in the beginning stage of the every test. This paper describes the number of maximum resistance and self propulsion test in a sheet of level ice and proposes the methodology to optimize pack ice, rubble ice, brash ice and ice ridge test in MOERI ice tank. The feasibility of free running test to know maneuvering performance in ice field and some specific idea to measuring ice thickness and ice ridge shape was proposed.

• 대한조선학회논문집
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• 제59권5호
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• pp.262-270
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• 2022

The emergence of new concept ships, such as autonomous ships, has drawn much attention on the manoeuvrability of ships because of the safe navigation and operation of ships. Although the manoeuvrability of KRISO Container Ship(KCS) has been frequently reported, there have been few documents of representative manoeuvre cases conducted in various methods by one institute. This paper presents the manoeuvrability of the ship in 1/42.0 model scale by 3 methods: free running model tests, horizontal planar motion mechanism tests, and computational fluid dynamics analysis. KRISO reports KCS manoeuvre data: 35° turning circle tests and 20/20(10/10) zigzag manoeuvring tests. In addition, a simple formula for integrating and comparing manoeuvre indices, Manoeuvrability Comparing Simple Index(MCSI), is proposed.

• 대한조선학회논문집
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• 제59권4호
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• pp.251-251
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• 2022

• 대한조선학회논문집
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• 제50권6호
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• pp.429-435
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• 2013

Recently, to improve the safety and maneuverability at fairway around harbor the POD system has been equipped on a ship. And the interest about maneuvering characteristics of a cruise ship has been increasing. In this paper the mathematical model of maneuvering motion of a cruise ship with twin POD system in general speed and slow speed are presented. And the maneuvering coefficients of mathematical model are obtained from the captive model tests using CPMC(Computerized Planar Motion Carriage). Computer simulation using mathematical model in general speed and slow speed are carried out and compared with the results of free running model test with the same model ship. The differences between the mathematical models are compared and discussed. In this paper the mathematical models, the results of captive model test and simulation results are presented.

• 한국항해항만학회지
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• 제40권6호
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• pp.353-360
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• 2016

IMO는 선박의 조종성능과 복원성능에 관한 국제적 기준 마련에 노력해 왔다. 이러한 움직임은 해상에서의 선박 안전 향상에 기여하였으며, 선박 연구자가 수행하는 학술적 연구의 방향에도 영향을 미쳤다. 기존의 수행된 선박 조종성능과 조종성능 연구는 각각 그 분야에서 독립적으로 수행되어 왔다. 두 분야의 상호 관계에 관한 연구는 미비한 실정이다. 이에 본 논문에서는 선박의 조종성능과 복원성능의 상호 관계를 정량적으로 규명하고자 기초적인 실험 연구를 수행하였다. 각 두 항목을 나타내는 지표로 복원성능은 GM 변화를 사용 하였고, 선박의 조종성능은 선회성능을 선택하여 이 두 지표의 상호관계에 관해 정량적인 분석을 시도하였다. 이를 위하여 자유 항주 모형선을 이용한 선회 실험을 실시하고, GM변화에 따른 선회 반경 및 선회 중 발생하는 최대 횡경사 각도의 변화를 분석 하였다. 실험 결과 GM에 따른 선회 반경 감소 및 초기 횡경사 증가의 경향이 서로 다르게 나타났다. 이를 이용하여, GM 감소에 따른 선회반경 및 초기 횡경사 변화 예측을 위한 개략적인 경향 추정식을 제안 하였다. 선박은 운항 중 예상하지 못한 원인으로 갑작스럽게 GM이 감소 할 수 있다. 본 논문에서 얻은 실험 결과는 GM감소량에 따른 선박의 선회반경 및 조타에 의한 횡경사 각도 변화 크기를 개략적으로 추정하기 위한 기초 자료로 활용 될 수 있을 것으로 기대된다.

• 대한조선학회논문집
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• 제42권2호
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• pp.105-112
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• 2005

IMO standards for ship manoeuvrability were applied from January 1, 2004. Though model test or sea trial in full load condition is needed, it is not always possible to get such data for every ships. Therefore it is required to study the effect of loading conditions on ship manoeuvrability. Approximate formulae to estimate the hydrodynamic forces acting on a ship and the 2nd overshoot angle of $10^{\circ}$/$10^{\circ}$ zig-zag test in certain loading condition are proposed in this study These were derived from the results of model test and sea trial data. Captive model tests for 7 ships with 15 different loading conditions and sea trial data including free running test of 6 cases were used. Compared with experiment data and prediction formulae already proposed by others, the approximate formulae in this study show good agreement with model test results.