• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.55-60
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• 2004

In this study, the configuration and tension of a towing cable for side-scan sonar are predicted in an ambient flow and at an unsteady towing condition. The governing equation of three-dimensional dynamic analysis for a flexible cable is solved using a finite difference method. We successfully predict the configuration and tension of a side-scan sonar and designed the towing system. It is found in static analyses that the side-scan sonar must be towed to keep a its stable depth at a reasonable speed. The study also reveals in the transient analyses that the dominant component affecting the top tension is the tangential drag force for the larger towing speed than the critical speed, and the self weight of a towed instrument for the smaller towing speed than. It should be maneuvered for a towing vessel with good consideration for the impact effect in a cable due to tension peak when a towing speed is suddenly increase. The developed program can be applicable for three-dimensional dynamic analysis of a towing system for various marine survey instruments.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.203-209
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• 2003

In this study, the configuration and tension of a towing cable for side-scan sonar are predicted in an ambient flow and at an unsteady towing condition. The governing equation of three-dimensional dynamic analysis for a flexible cable is solved using a finite difference method. We successfully predict the configuration and tension of a side-scan sonar and designed the towing system. It is found in static analyses that the side-scan sonar must be towed to keep a its stable depth at a reasonable speed. The study also reveals in the transient analyses that the dominant component affecting the top tension is the tangential drag force for the larger towing speed than the critical speed, and the soft weight of a towed instrument for the smaller towing speed than. It should be maneuvered for a towing vessel with good consideration for the impact effect in a cable due to tension peak when a towing speed is suddenly increase. The developed program can be applicable for three-dimensional dynamic analysis of a towing system for various marine survey instruments.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1095-1104
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• 2022

The towing cable plays a role in dropping and salvaging the Towed Array Sonar System (TASS) into the water and transmitting the signal (information) detected by the sonar in the water to the probe or surface ship. The towing cable consists of a heavy cable and a lightweight cable in detail. The towing cable for sonar is characterized by high reliability and durability as the underwater environment deteriorates as the operating depth increases. Due to these restrictions, cases designed and manufactured in Korea are extremely rare. The core technology for towing cable design secured through this study is expected to be used in various ways in the defense industry and the private sector.

• Journal of Ocean Engineering and Technology
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• v.23 no.1
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• pp.74-80
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• 2009

In this study, the static and modal analyses to find the characteristic of eigenvalues for a towed cable were with a free boundary condition at the bottom end carried out with numerical study. The resulting numerical code with finite element method was used to study sample problems for a cable with towing speeds. After tracing the equilibrium state with a towing speed through the static analysis, modal analysis on the basis of static results was performed. The static top tension for a critical towing speed is nearly 50 percent of what it was for a free hanging pipe. From static analyses, it is found that towing speed has a noticeable effect on top tension of a towed pipe. At a high towing speed, differences between the first and second periods become larger. Compared to the fundamental period for a free hanging pipe, that for a towed pipe with a critical towing speed is approximately 1.4 times larger. This result is very important point in that the lock in condition and tension of the towed cable system with top excitation can be predicted. The corrected close form solution to solve natural periods for a towed cable was presented in this study. The code is validated by comparison of the results of theoretical and numerical studies. Two results were in very good agreement. This study can contribute to predicting the lock-in condition and tension for a towed cable or pipe with top excitation.

• Journal of computational fluids engineering
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• v.16 no.1
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• pp.7-13
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• 2011

The fluid-structure interaction of a towed body is simulated using a developed code, which is based on the flux-difference splitting scheme on the hybrid Cartesian/immersed boundary method. To improve the stability in the coupling between the fluid and structure domains, a scheme is used, in which the effects of structure deformation are treated implicitly. The developed code is validated for the fluid-structure interaction problem through comparisons with other results on the vortex-induced vibration of elastically mounted cylinders. To simulate behavior of a towed body, an asymmetric tension modelling for a towing cable is suggested. In the suggested model, the tension is proportional to the elongation of the cable, but the cable has no effect on the body motion whenever the distance between the endpoints of the cable is smaller than the original length of the cable. The fluid-structure interactions of a towed body are simulated on the basis of different parameters of the towing cables. It is observed that the suggested tension model predicts the snapping for a shorter towing cable, which is in accordance with the reported results.

• Journal of the Korean Society of Marine Environment & Safety
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• v.4 no.2
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• pp.63-68
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• 1998

This study is aimed to predict the configuration and tension of a towing cable of a side-scan sonar which plays an important role in developing ocean resources. The governing equations of 3-D static equilibrium equations for a flexible cable are derived and solved using a finite difference method. The forces considered in this paper are effective weights, drag forces due to currents and ship moving, and the tension at both ends of the towing cable. The governing equations are non-linear, so an iteration method is applied to solve the equation. A case study is carried out for several different conditions. The result will be useful for predicting the location of a side-scan sonar and to design the towing system.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.4
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• pp.353-358
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• 1999

Tabulated results by Pode are used for computing the cable shape and cable tension in static equilibrium. This paper describes a technique using the integral form by Pode to give a simplified calculation of the cable functions at any desired value because in most practical cased the points of interest on the cable are not the points of reference on which the tables are based. Solving the nondimentional tension, $\tau$, defined by Pode in closed form reduces the integral in cable functions to a single integral. The technique using the integral form enables us to calculate the cable functionsin at any critical angle and at any point in case of a towing cable or certain cable-buoy systems.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.2
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• pp.409-425
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• 2015

In this paper, we employ a dynamics modeling method for investigating a multi-body dynamics system of semi-submersible autonomous underwater vehicles consisting of a towing vehicle operated near the water surface, a tow cable, and a towfish. The towfish, which is towed by a marine cable for the purposes of exploration or mine hunting, is modeled with a Six-Degree-of-Freedom (6-DOF) equation of motion that reflects its hydrodynamics characteristics. The towing cable, which can experience large displacements and deformations, is modeled using an absolute nodal coordinate formulation. To reflect the hydrodynamic characteristics of the cable during motion, the hydrodynamic force due to added mass and the drag force are imposed. To verify the completeness of the modeling, a few simple numerical simulations were conducted, and the results confirm the physical plausibility of the model.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.2
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• pp.113-121
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• 2005

How to extimate the angle of attack of a vertical V-type cambered otter board was described. A three-dimensional semi-analytic treatment of a towing cable system was applied to the field experiments of a midwater trawl obtained by the Scanmar system. Also the equilibrium condition of the horizontal component and vertical component of forces and moment around the otter board was used. When the warp length was 300m long and the towing speed was between 2.61 and 3.86 knots, the estimated angle of attack of the otter board was ranged between $24.7^{\circ}$ and $26.2^{\circ}$, though the maximum lift force was at the angle of attack $22^{\circ}$.

• Journal of Ocean Engineering and Technology
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• v.34 no.5
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• pp.334-341
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• 2020

Most towfish systems do not have propulsive devices and cannot compensate for perturbation motion, which can affect the observation data. This paper discusses attitude control of a towfish with elevators on the left and right tail wings to improve the quality of the observational data. Specifically, we investigate the relationships between the towing point, the center of gravity, and the drag forces produced by the elevators to clarify whether the elevators can control the attitude of the towfish sufficiently for various positions of the towing point and center of gravity. The feasible positions of the towing point and center of gravity are defined by mechanical analyses, and simulations are conducted to verify that the elevators can provide attitude control in these positions. The simulation results show that at some positions, the elevators can control the attitude quickly and sufficiently even if disturbances exist.