• Journal of the Institute of Convergence Signal Processing
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• v.20 no.4
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• pp.186-192
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• 2019

In general, many marine organisms are attached to the bottom of a ship in operation or a ship in construction. Due to this phenomenon, the roughness of the ship surface increases, resulting in loss of ship speed, resulting in economic losses and environmental pollution. This study acquires / utilizes camera images attached to ship's bottom and underwater drones to check the condition of bottom. The acquired image will determine the roughness according to marine life by the administrator's visual confirmation. Therefore, by applying a filter algorithm to correct the image to the original image can help in the correct determination of whether or not attached to marine life. Various correction filters are required for the underwater image correction algorithm, and the lighting suitable for the dark underwater environment has a great influence on the judgment. The results of the research test according to the calibration algorithm and the roughness of each algorithm are considered to be applicable to many fields.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.1
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• pp.38-48
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• 2020

In order to inspect the existing or newly constructed ship's hull, a professional diver directly inspects the ship's bottom of the water. However, since it is a work done by people, there are many dangers such as human casualties and crashes. To solve this problem, it is necessary to develop underwater drones for ship inspection for visual inspection. The technology applied to underwater drones, the use and manufacturing process of each component, and the method of manufacture such as firmware development were described, and the difference was compared by measuring the drone's own driving ability and driving ability using crawler under water, and the location tracking device test confirmed the error from the actual location. It is estimated that the use of underwater drones produced through this research will prevent human casualties and achieve economic effects and stability.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.3
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• pp.133-141
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• 2020

In this paper, the communication method of data information accepted by underwater drones and the implementation method to console display of data information were described, and the function of integrated monitoring system interface and the design and implementation of sonar interface were explained. The operation and posture of underwater drones can be controlled using a controller connected to the console, and the distance information between underwater drones and obstacles is obtained from sonar so that they can be visually displayed on the console screen along with camera images. The integrated monitoring navigation console is implemented to suit improvements, making it convenient and easy for workers to use. In addition, by upgrading integrated monitoring and control software functions, the company added user-specific project management functions and the output of reports for hull inspection to make them different and competitive from other underwater drones.

• Journal of Ocean Engineering and Technology
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• v.30 no.5
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• pp.374-380
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• 2016

The large drift and angle of attack motion of an ROV (Remotely operated vehicle) cannot be modeled using the typical hydrodynamic coefficients of conventional straight running AUVs and specific slender bodies. In this paper, the ROV hull is divided into several simple-shaped components to model the hydrodynamic force and moment. The hydrodynamic force and moment acting on each component are modeled as the components of added mass force and drag using the known values for simple shapes such as a cylinder and flat plate. Since an ROV is operated under the water, the only environmental force considered is the current effect. The target ROV dealt with in this paper has six thrusters, and it is assumed that its maneuvering motion is determined using a thrust allocation algorithm. Tracking simulations are carried out on the ship’s surface near the stern, bow, and midship sections based on the modeling of the hydrodynamic force and current effect.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.2
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• pp.92-100
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• 2020

Currently, the demand for underwater or underwater photography is growing very fast. Its coverage of underwater shooting for broadcasting, leisure and sports, and military and operational use is also growing rapidly. Among them, we specifically select the best camera to be used in underwater drones to photograph and inspect marine life attached to the ship's hull. To compare three cameras performance, they are compared and evaluated using objective and subjective criteria in special circumstances such as underwater shooting. This study checks whether performance criteria, such as resolution of a camera, meet objective and subjective standards in the unusual situation of underwater shooting. And it shows that in addition to the filter that calibrates the image, proper camera selection is important for providing good picture quality. Even after this study, research using more diverse cameras could provide an appropriate standard for comparison of underwater camera quality.

• Journal of Navigation and Port Research
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• v.30 no.6 s.112
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• pp.439-446
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• 2006

In ship structures many of the structural plates have cutouts, for example, at inner bottom structure, girder, upper deck hatch, floor and dia-frame etc. In the case where a plate has a cutout it experiences reduced buckling and ultimate strength and at the same time the in-plane stress under compressive load produced by hull girder bending will be redistributed In general, actual ship structure adopted reinforcement of stiffener around the cutout in order to preventing from buckling so it need to examine a buckling and ultimate strength behaviour considering a cutout because In many ship yards used class rule for calculating buckling strength but it is difficult to evaluate perforate stiffened plate with random size. In the present paper, we investigated several kinds of perforated stiffened model from actual ship and then was performed finite element series analysis varying the cutout ratio, web height, thickness and type of cross-section using commercial FEA program(ANSYS) under compressive load.

• Journal of Navigation and Port Research
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• v.31 no.5 s.121
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• pp.435-445
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• 2007

Ship structures are thin-walled structures and lots of cutouts, for example, of inner bottom structure, girder, upper deck hatch, floor and dia-frame etc. In the case where a plate has cutout it experiences reduced buckling and ultimate strength and at the same time the in-plane stress under compressive load produced by hull girder bending will be redistributed. In the present paper, we investigated several kinds of perforated stiffened model from actual ship structure and series of elasto-plastic large deflection analyses were performed to investigate into the influence of perforation on the buckling and ultimate strength of the perforated stiffened plate varying the cutout ratio, web height, thickness and type of cross-section by commercial FEA program(ANSYS). Closed-form formulas for predicting the ultimate strength of the perforated stiffened plate are empirically derived by curve fitting based on the Finite Element Analysis results. These formulas are used to evaluate the ultimate strength, which showed good correlation with FEM results. These results will be useful for evaluating the ultimate strength of the perforated stiffened plate in the preliminary design.

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.141-146
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• 2005

Ship have cutout inner bottom and girder and floor etc. Ship's structure is used much, and structure strength must be situated, but establish new concept when high stress interacts sometimes fatally the area. There is no big problem usually by aim of weight reduction, a person and change of freight, piping etc. Because cutout's existence grow up in this place, and, elastic buckling strength by load causes large effect in ultimate strength. Therefore, stiffened perforated plate considering buckling strength and ultimate strength is one of important design criteria which must examine when decide structural concept at initial design. Therefore, and, reasonable buckling strength about perforated stiffened plate need to ultimate strength limited design . Calculated ultimate strength varied several web height and cutout's dimension, and thickness in this investigated data. Used program(ANSYS) applied F.E.A code based on finite element method.