• 한국해양공학회지
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• 제33권5호
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• pp.462-469
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• 2019

In this study, a motion control problem for the vessels towed by tugboats or towing ships on the sea is considered. The towed vessels, such as barge ships, are used for several purposes. Generally, these vessels have no power propulsion system and are towed using ropes and towing vessel (tugboats). The basic mathematical model of the towed vessel in which three active rudders are attached was introduced from a previous study. Owing to the dependency of the motions of the towed vessel to the towing ship, a method is suggested to cope with the undesirable disturbance and improve the tracking performance. For the simulation study, a model of the towed vessel with a towing ship is made, and necessary physical parameters are identified from the experiment. For the defined and linearized model, a control system is designed, and the control performance is also evaluated. A simulation study is conducted and the effectiveness of the proposed control strategy is verified.

• 해양환경안전학회지
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• 제19권6호
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• pp.637-642
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• 2013

본 연구는 피예인선의 거동을 결정짓는 예인선의 힘과 작용지점의 해석에 대해 언급하고 있다. 예인대상선박의 간략화된 동역학방정식을 바탕으로 선형화기법을 적용하여 목적으로 하는 피예인선의 자세와 위치를 달성하기 위한 예인력과 예인력이 가해져야 하는 지점을 도출하였다. 이를 위해 LQR제어기법을 적용하였으며, 수치적인 시뮬레이션을 수행하였다. 리카치방정식을 이용하여 피예인선의 자세제어를 위한 제어기 이득과 자세제어에 필요한 무게중심에서의 힘을 도출하였고, 도출한 힘과 예인지점의 역학적인 관계는 의사역행렬을 이용하여 구하였다. 이러한 해석기법을 바탕으로 피예인선을 초기위치로부터 목표위치로 예인할 때 예인지점 및 예인방식에 따른 예인력을 구할 수 있었다. 최종적으로 선박을 예인하기 위한 예인력은 예인지점과 방향에 밀접하게 연관되어 있는 것을 확인할 수 있었고 이러한 연구결과는 사고선박의 구난작업 시 예인선의 배치에도 적용이 가능할 것이다.

• 한국항해학회지
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• 제23권4호
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• pp.21-28
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• 1999

In some cases a towing vessel and her tow, a fishing boat, and a vessel at anchor have a priority against a general power-driven vessel underway in the application of collision rule. This article aims at suggesting a practical guide for the construction of the meaning of a vessel engaging in fishing, a vessel engaged in towing operation such as severely restricts the towing vessel and her tow in their ability to deviate from their course and a vessel at anchor, which are permitted to have the above priority. The construction of the application of the collision rule on the above vessels is supported by the decisions of MAIA and the judgment of civil courts.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.12-23
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• 2021

In the conventional experiment to assess the towing operations, the towing stability of the towed vessel has been evaluated under the condition without lateral motion of the tug-boat. However, the tug-boats may have a lateral force to change the direction of the towed vessel. In this study, experiments have been conducted considering unsteady conditions in the towing system. First, a towing test system in a Circular Water Channel (CWC) using the conventional experimental method is built. Second, the towing characteristics of the towed vessel are investigated using the conventional method, and they are compared with other research results and stability discriminant criteria. Third, the lateral motion of the tug-boat was modeled as a sinusoidal motion using a forced oscillation device changing frequency and amplitude. Finally, the discussion is given in terms of both towing- and course-stability of the towed vessel according to the lateral motion of the tug-boat.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.943-956
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• 2020

In this study, the motion control problem of the vessel towed by a towing ship (tugboat) is considered. The non-powered towed ship is dragged by the towing ship. Even though the towed ship is equipped with propulsion systems, they cannot be used at low or constant speeds due to safety issues. In narrow canals, rivers, and busy harbor areas especially, where extreme tension is required during towing operation, the course stability of the towed vessel depends on the towing ship. Therefore, the authors propose a new control strategy in which the rudder system of the towed vessel is activated to provide its maneuverability. Based on the leader-follower system configuration, a nonlinear mathematical model is derived and a back-stepping control is designed. By simulation and experiment results with a comparison study, the usefulness and effectiveness of the proposed strategy are validated.

• 수산해양기술연구
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• 제56권3호
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• pp.238-245
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• 2020

In this study, a motion control problem for the vessel towed by towing ship on the sea is considered. The towed vessel does not have self-control capabilities such that its course stability totally depends on the towing ship. Especially, in the narrow canal, river and congested harbor area, extreme tension is required during the towing operation. The authors, therefore, propose a new control system design method in which the rudder is activated to provide its maneuverability. Based on the leader following system configuration, a nonlinear mathematical model is derived and a backstepping control is designed. By experiment results with nonlinear control framework, the usefulness and effectiveness of the proposed strategy are presented.

• 수산해양기술연구
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• 제54권4호
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• pp.343-352
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• 2018

In this study, a motion control problem for the vessels towed by tugboats or towing ships on the sea is considered. The towed vessel looks like the barge ship, which is used for many purposes. In these vessels, basically, the power propulsion system is not installed but just towed by a towing vessel such as tugboats with ropes and wires. It means that the motions of towed vessel are basically dependent on the tracking route of towing boat. Therefore, in some cases, undesirable and unpredictable motions may be made by environmental factors such as wave, wind attack and so on. As a result, a collision accident with others may occur during maneuvering situation. Based on these facts, the authors try to encourage the steering performance of the towed vessel by using controllable rudders without any propulsion system. In this study, especially, a controllable vessel with three rudders is considered, and a mathematical model is induced for the future study. The model is described as surge, sway motion and inertia moment by following the general representation method for the surface ship.

• 한국수산과학회지
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• 제41권2호
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• pp.140-149
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• 2008

This study evaluated the efficiency of an oil fence and spreading devices for one vessel in a towing tank. A series of model experiments and numerical calculations were conducted using an existing oil fence for two vessels and a new method for one vessel. Models of the oil fence and spreading devices were constructed on $1/20^{th}$ scale from waterproofed nylon fabric and canvas. The tensions acting on the model of the oil fences and the horizontal distance between the spreading devices were calculated numerically while the oil fences were being towed. The results were extremely close to the results of the model experiments. The ratio of the opening width to the total length of the oil fence, which shows the efficiency of the oil fence for one vessel, was 49.7% in 0.4 m/sec. Therefore, the proposed oil fence system should be very useful for oil containment at sea. As the opening width of the oil fence is not proportional to the length of the towing rope, it may be reasonable to maintain the towing rope at approximately 100 m. Furthermore, a reasonable towing speed, when operating the oil fence for one vessel equipped with spreading devices, was within 0.4 m/sec.

• 한국항해항만학회지
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• 제38권5호
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• pp.463-470
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• 2014

본 논문에서는 선박의 예인에 필요한 예인력의 계산과 이를 검증하기 위한 실험 결과에 대해 언급하고 있다. 먼저 예인력의 계산에 있어서는 선박의 마찰저항, 풍압저항, 조파저항을 고려하였다. 아울러 프로펠러가 고착된 상태를 가정하여 프로펠러 저항을 계산하였다. 이와 더불어 예인 시 사용되는 예인삭에 걸리는 부가저항을 노드분석법을 적용하여 계산하였고, 선체 저항과 예인삭에서의 부가저항을 합하여 최종적인 예인저항을 도출하였다. 계산된 결과값의 유효성을 검증하기 위하여 목포해양대학교 실습선 새유달호를 활용하여 해상에서 예인실험을 수행하였고 이론적인 계산 결과와 실험 결과에 대한 비교를 행하였다. 소요 예인력의 이론적인 계산에서 주요한 요소는 예인속력임을 알 수 있었고, 예인속력의 증가에 따라 프로펠러 고착 저항이 저항의 주요한 부분을 차지하는 것을 확인하였다. 실제 실험을 통해서는 선박의 요잉에 의한 저항 증가분을 고려하는 것이 필요하다는 것을 알 수 있었다.

• 수산해양기술연구
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• 제46권4호
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• pp.476-486
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• 2010

Fishing efficiency of a trawl vessel can be enhanced by increasing the swept area per unit time, which can be attained either by increasing the mouth size of the net, or by increasing the towing speed. To improve fishing and fuel efficiency of trawl vessels targeting fishes of greater mobility, in which the towing speed is more critical in determining fishing efficiency, we conducted a series of model tests to evaluate the performance of the newly-designed nozzle propeller before installing it in a trawl vessel to verify its towing speed and fuel efficiency in the sea. By conducting further model tests in the experimental basin, we redesigned the propeller of stern trawler to improve the resistance and propulsion performance. Through actual fishing operations, we evaluated the improvement in fuel and fishing efficiency by installing the new nozzle propeller. The trawling speed increased by 0.6kts at the same engine power (RPM), while the engine margin increased by more than 20%. The increased towing speed by installing the redesigned propeller is expected to enhance fishing performance through increasing the number of hauling- and casting operations per unit times, while shortening the towing duration. Analysis of the Catch-Per-Unit-Effort (CPUE) data indicated that the mean CPUE of trawl fishery increased from 3.04kg/m in year 2007 to 6.15kg/m in year 2008, confirming enhanced fishing efficiency by adopting the redesigned propeller.