• 한국해양공학회지
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• 제35권1호
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• pp.13-23
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• 2021

Since the introduction of the mandatory energy efficiency design index (EEDI), several studies have been conducted on the maneuverability of waves owing to the decrease in engine power. However, most studies have used the mean wave force during a single cycle to evaluate maneuverability and investigated the turning performance. In this study, we calculated the external force in accordance with the angle of incidence of the wave width and wavelengths encountered by KVLCC2 (KRISO very large crude-oil carrier) operating at low speeds in regular waves using computational fluid dynamics (CFD). We compare the model test results with those published in other papers. Based on the external force calculated using CFD, an external force that varies according to the phase of the wave that meets the hull was derived, and based on the derived external force and MMG control simulation, a maneuvering simulation model was constructed. Using this method, a weather vaning simulation was performed in regular waves to evaluate the course-keeping ability of KVLCC2 in waves. The results confirmed that there was a difference in the operating trajectory according to the wavelength and phase of the waves encountered.

• 수산해양기술연구
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• 제28권1호
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• pp.21-26
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• 1992

Generally a navigator evaluated the maneuverability of his ship by the scale of turning circle which was described only by the largest rudder angle of the port and starboard sides. But to have the sufficient knowledge of his ship's maneuvering characteristics he should consider the data about the new course keeping test, the spiral test, and the turning circle tests in accordance with the rudder angles together. In this paper the author performed the above tests to study the maneuverability of the stern trawler M.S. Pusan 404 which is a training ship of the National Fisheries University of Pusan. The obtained results are summarized as follows: 1. When the rudder angles being 5。, 10。, 20。, 30。, 35。 the advances of the starboard side turning circles were 12.8, 8.2, 4.8, 2.9, 2.7 times as large as the length of the ship, and of the port side turning circles were 13.3, 8.7, 5.4, 3.5, 2.9, time as large as the large as it. Under the same conditions the tactical diameters were 15.1, 9.7, 5.2, 3.1, 2.8 times as large as the length of the ship, for starboard side, and 17.2, 12.4, 6.4, 3.7, 3.2 times as large as it for port side. 2. As the rudder angle being increased the ratio of the advance to the tactical diameter was nearly 1 and her obeying ability was better than that of the small angle. 3. The mean values of the rates of speed reduction during the steady turning motion were 0.96, 0.92, 0.82, 0.71, 0.65 in accordance with the rudder angles. 4. The relative formulas between the distance to the new course y and the altering course x were as follows: When rudder angles being 10。, 20。, 30。, y=52.2222+1.6133x, y=48.750+0.9383x, y=39.250+0.655x respectively. 5. There was little difference of the distance to the new course between rudder angle 20。and 30。, and so it is desirable for a navigator to a navigator to use the small rudder angles unless sudden emergencies. 6. Though her rudder angle being small her course stability was good according to the spiral tests.

• 대한조선학회논문집
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• 제47권4호
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• pp.496-507
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• 2010

It is well known that when a high-speed planing craft travels in following seas it experiences long-periodic motions due to low encounter frequency, and it often loses its course keeping stability. Therefore, it is necessary to study the sea-keeping performance and stability of it in the following seas. In this paper, the vertical motions of a planing craft were measured in following regular waves, and the test results were compared with the theoretical results. In the case of the same encounter frequency, non-dimensionalized motion amplitudes become larger as Froude number is higher, and non-dimensionalized motion amplitudes in head waves are larger than those in following waves. The mean values of the motions in following waves are similar to the running attitudes of a craft in calm water at the same Froude number.

• Geomechanics and Engineering
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• 제20권3호
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• pp.221-232
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• 2020

In many tropical regions, soil structures often fail under constant loads as a result of decreasing matric suction due to water infiltration. Most of the previous studies have been performed by infiltrating water in the soil specimen by keeping shear stress constant at 85-90% of peak shear strength in order to ensure specimen failure during water infiltration. However, not many studies are available to simulate the soil behavior when water is infiltrated at lower shear stress and how the deformations affect the soil behavior if the failure did not occur during water infiltration. This research aimed at understanding both the strength and deformation behavior of unsaturated soil during the course of water infiltration at 25%, 50% and 75% of maximum deviatoric stress and axial strain by keeping them constant. A unique stress-strain curve expresses the transient situation from unsaturated condition to failure state due to water infiltration is also drawn. The shearing-infiltration test results indicate that the water infiltration reduces matric suction and increase soil deformation. This research also indicates that unsaturated soil failure problems should not always be treated as shear strength problems but deformation should also be considered while addressing the problems related to unsaturated soils.

• 한국항해항만학회지
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• 제34권7호
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• pp.525-532
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• 2010

Mobile Harbor (MH) is a new transportation platform that can load and unload containers onto and from very large container ships at sea. It could navigate near harbors where several vessels run, or it could navigate through very narrow channels. In the conceptual design phase when the candidate design changes frequently according to the various performance requirements, it is very expensive and time-consuming to carry out model tests using a large model in a large towing tank and a free-running model test in a large maneuvering basin. In this paper, a new Planar Motion Mechanism(PMM) test in a Circulating Water Channel (CWC) was conducted in order to determine the hydrodynamic coefficients of the MH. To do this, PMM devices including three-component load cells and inertia tare device were designed and manufactured, and various tests of the MH such as static drift test, pure sway test, pure yaw test, and drift-and-yaw combined test were carried out. Using those coefficients, course-keeping stability was analyzed. In addition, the PMM tests results carried out for the same KCS (KRISO container ship) were compared with our results in order to confirm the test validity.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권3호
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• pp.466-477
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• 2015

In this study, a numerical prediction method on manoeuvrability of Wind Turbine Installation Vessel (WTIV) is presented. Planar Motion Mechanism (PMM) captive test for the bare hull of WTIV is carried out in the model basin and compared with the numerical results using RANS simulation based on Open-source Field Operation And Manipulation (OpenFOAM) calculation to validate the developed method. The manoeuvrability of WTIV with skeg and/or without skeg is investigated using the numerical approach along with the captive model test. In the numerical calculations, the dynamic stability index which indicates the course keeping ability is evaluated and compared for three different hull configurations i.e. bare hull and other two hulls with center skeg and twin skeg. This paper proves that the numerical approach using RANS simulation can be readily applied to estimate the manoeuvrability of WTIV at the initial design stage.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2017년도 추계학술대회
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• pp.19-21
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• 2017

Ship maneuvering performance is usually estimated in calm water conditions which provide valuable information about the ship maneuvering characteristics at the early design stage. However, the course-keeping ability and the maneuvering performance of a ship can be significantly affected by the presence of waves when ship maneuvers in real sea condition. Therefore, it is necessary to understand the maneuvering behavior of a ship in waves in the viewpoint of ship safety in the design stage. In this study, the force and yaw moment acting on a moving ship in regular waves with different wave length and wave direction will be performed in the square wave tank in Changwon National University. The results of this study can be used to help a person to design a ship hull with the best ship maneuverability in waves and disseminate knowledge on predicting ship maneuvering in regular waves in various wave directions.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 춘계학술대회 논문집
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• pp.117-122
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• 2000

In these days, the pollution of marine environment near island at Korean coastal zone caused by the trash, human waste and livestocks excreta become series problem. One of the most economic and efficient way to prevent this pollution problem is to set up island circulating incineration system. In this paper, the results of feasibility study on the application of turtle boat hull form to the incinearting vessel has been summarized especially for the resistance and course keeping point of view.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.216-217
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• 2005

This paper presents an integrated navagation control concept for underwater vehicles under high speed navigation circumstance. First of all, in order to control an underwater vehicle with respect to automatic navigation, an integrated navigation control method is suggested in view of synchronous control for course keeping, diving and depth control. An exact nonlinear model equation with six-degree-of-freedom is derived for control algorithm. To identify various hydrodynamic coefficients of the equation, an experimental approach is introduced and results are demonstrated for MANTA type model.

• 해양환경안전학회지
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• 제27권1호
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• pp.38-46
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• 2021

4차 산업혁명 시대를 맞이하면서 첨단기술이 산업 전반에 사용됨에 따라 자율운항선박기술에 대한 관심이 고조되고 있다. 이에 본 연구에서는 자율운항선박에 대한 기초 연구로써 모형 선박을 제작하고 드론에 사용되는 아두파일럿(Ardupilot)을 적용시켜 자율운항 제어 시스템을 구축하였다. 구축된 모형선을 활용하여 다양한 항해계획을 실행함으로써 자율운항 선박의 운항 자동제어 가능성을 확인하였다. 침로안정성 실험에서는 모형선이 정해진 침로를 똑바로 따라가지 못하고 지그재그(S자 형태)로 항행하면서 침로에서 최대 5.4 m(4.5 L) 이탈하였으며, 매개변수를 수정하여 이탈거리를 최대 1.8 m(1.5 L)까지 감소시켰다. 선회성능 실험에서는 선회권의 직경이 최대 약 9.3 m(7.8 L)로 나타났는데 매개변수를 수정하여도 큰 변화를 확인할 수 없었다. 하지만 WP 도착 전 감속하도록 실험한 결과 선회권의 직경이 최대 약 3.2 m(2.7 L)로 감소된 것을 확인할 수 있었다. 정지성능을 평가하기 위해 모든 실험의 마지막 정지 예정 위치와 실제 모형선이 정지한 위치를 상호 비교하였으며, 정지 예정 위치로부터 최소 0.4 m(0.3 L), 최대 6.2 m(5.2 L) 떨어진 지점에서 모형선이 정지하였음을 확인할 수 있었다. 추후 다양한 매개변수의 수정·보완을 통한 성능 향상이 이루어진다면 자동제어를 통한 자율운항선박의 자동접안을 위한 연구를 진행할 계획이다.