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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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International Journal of Ocean System Engineering
Journal Basic Information
Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 3, Issue 4 - Nov 2013
Volume 3, Issue 3 - Aug 2013
Volume 3, Issue 2 - May 2013
Volume 3, Issue 1 - Feb 2013
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Hydrodynamic Hull Form Design Using an Optimization Technique
Park, Dong-Woo ; Choi, Hee-Jong ;
International Journal of Ocean System Engineering, volume 3, issue 1, 2013, Pages 1~9
DOI : 10.5574/IJOSE.2013.3.1.001
A design procedure for a ship with minimum resistance had been developed using a numerical optimization method called SQP (Sequential Quadratic Programming) combined with computational fluid dynamics (CFD) technique. The frictional resistance coefficient was estimated by the ITTC 1957 model-ship correlation line formula and the wave-making resistance coefficient was evaluated by the potential-flow panel method with the nonlinear free surface boundary conditions. The geometry of the hull surface was represented and modified by B-spline surface modeling technique during the optimization process. The Series 60 (
=0.60) hull was selected as a parent hull to obtain an optimized hull that produces minimum resistance. The models of the parent and optimized hull forms were tested at calm water condition in order to demonstrate the validity of the proposed methodolgy.
Hardware-In-the-Loop Simulation for Development of Fin Stabilizer
Yoon, Hyeon Kyu ; Lee, Gyeong Joong ;
International Journal of Ocean System Engineering, volume 3, issue 1, 2013, Pages 10~15
DOI : 10.5574/IJOSE.2013.3.1.010
A ship cruising in the ocean oscillates continuously due to wave action. In order to reduce the ship's roll, we developed a fin stabilizer as an anti-rolling device for a 500-ton-class high-speed marine vessel. During the development phase, it was necessary to set up control gains for the motion and hydraulic systems and assess the effectiveness of the anti-rolling performance on the ground. For this reason, a Target Simulator, which simulated the ship's motion, was given operator inputs such as the engine telegraph and waterjet deflection angle, and generated roll using a one-degree-of-freedom motion base. Hardware-In-the-Loop Simulation (HILS) was performed using the Target Simulator in order to confirm the various logics of the developed fin stabilizer, select initial control gains, and estimate the anti-rolling performance. In conclusion, it was confirmed that HILS was very helpful to develop the fin stabilizer because it could reduce the number of sea trial tests that were needed and could find many malfunctions in the factory a priori.
Design of Fuzzy PD Depth Controller for an AUV
Loc, Mai Ba ; Choi, Hyeung-Sik ; Kim, Joon-Young ; Kim, Yong-Hwan ; Murakami, Ri-Ichi ;
International Journal of Ocean System Engineering, volume 3, issue 1, 2013, Pages 16~21
DOI : 10.5574/IJOSE.2013.3.1.016
This paper presents a design of fuzzy PD depth controller for the autonomous underwater vehicle entitled KAUV-1. The vehicle is shaped like a torpedo with light weight and small size and used for marine exploration and monitoring. The KAUV-1 has a unique ducted propeller located at aft end with yawing actuation acting as a rudder. For depth control, the KAUV-1 uses a mass shifter mechanism to change its center of gravity, consequently, can control pitch angle and depth of the vehicle. A design of classical PD depth controller for the KAUV-1 was presented and analyzed. However, it has inherent drawback of gains, which is their values are fixed. Meanwhile, in different operation modes, vehicle dynamics might have different effects on the behavior of the vehicle. In this reason, control gains need to be appropriately changed according to vehicle operating states for better performance. This paper presents a self-tuning gain for depth controller using the fuzzy logic method which is based on the classical PD controller. The self-tuning gains are outputs of fuzzy logic blocks. The performance of the self-tuning gain controller is simulated using Matlab/Simulink and is compared with that of the classical PD controller.
Heuristic Physical Theory of Diffraction for Impedance Polygon
Lee, Keunhwa ; Park, Sanghyun ; Kim, Kookhyun ; Seong, Woojae ;
International Journal of Ocean System Engineering, volume 3, issue 1, 2013, Pages 22~32
DOI : 10.5574/IJOSE.2013.3.1.022
A heuristic physical theory of diffraction (PTD) for an acoustic impedance wedge is proposed. This method is based on Ufimtsev's three-dimensional PTD, which is derived for an acoustic soft or hard wedge. We modify the original PTD according to the process of physical optics (or the Kirchhoff approximation) to obtain a 3D heuristic diffraction model for an impedance wedge. In principle, our result is equivalent to Luebbers' model presented in electromagnetism. Moreover, our approach provides a useful insight into the theoretical basis of the existing heuristic diffraction methods. The derived heuristic PTD is applied to an arbitrary impedance polygon, and a simple PTD formula is derived as a supplement to the physical optics formula.
Corrosion Characteristics of Reinforced Steel Bar Emedded in Multiple Mortar Specimen(W/C:0.5) Aged 5 Years in Seawater
Moon, Kyung-Man ; Takeo, Oki ; Won, Jong-Pil ; Park, Dong-Hyun ; Kim, Yun-Hae ;
International Journal of Ocean System Engineering, volume 3, issue 1, 2013, Pages 33~37
DOI : 10.5574/IJOSE.2013.3.1.033
Reinforced concrete structures have been increasingly widely used in numerous industrial fields. These structures are often exposed to severely corrosive environments such as seawater, contaminated water, acid rain, and the seashore. Thus, the corrosion problems that occur with the steel bars embedded in concrete are very important from the safety and economic points of view. In this study, the effects of the cover thickness on the corrosion properties of reinforced steel bars embedded in multiple mortar test specimens immersed in seawater for 5 years were investigated using electrochemical methods such as the corrosion potentials, polarization curves, cyclic voltammograms, galvanostat, and potentiostat. The corrosion potentials shifted in the noble direction, and the value of the AC impedance also exhibited a higher value with increasing cover thickness. Furthermore, the polarization resistance increased with increasing cover thickness, which means that the oxide film that is deposited on the surface of a steel bar surrounded by alkali environment exhibits better corrosion resistance because the water, chloride ions and dissolved oxygen have difficulty penerating to the surface of the steel bar with increasing cover thickness. Consequently, it is considered that the corrosion resistance of reinforced steel can be improved by increasing the cover thickness. However, the corrosion resistance values of a steel bar estimated by measuring the corrosion potential, impedance and polarization resistance were not in good agreement with its corrosion resistance obtained by polarization curves.
Development of Heating Table Fabrication Process for the High Speed Curing Composites
Kim, Yun-Hae ; Ha, Jin-Cheol ; Lee, Jin-Woo ; Park, Jun-Mu ; Han, Joong-Won ; Choi, Byung-Keun ; Moon, Kyung-Man ; Nisitani, Hironobu ;
International Journal of Ocean System Engineering, volume 3, issue 1, 2013, Pages 38~43
DOI : 10.5574/IJOSE.2013.3.1.038
Wind turbine generator is, recently, becoming bigger and bigger. So, in order to produce large amounts of electricity generation, we have to consider the length and thickness of the blade. We investigated the skills of processing for making the super thickness laminate through development fabrication process for high speed curing composite heating table.
Underwater Acoustic Positioning System Design for Shallow Water Depth Application
Kim, Kihun ; Jang, In-Sung ;
International Journal of Ocean System Engineering, volume 3, issue 1, 2013, Pages 44~48
DOI : 10.5574/IJOSE.2013.3.1.044
This paper describes the design and implementation of a practical underwater positioning system, which is applicable for shallow water depth conditions. In this paper, two strategies are used to enhance the navigation performance. First, a low-cost acoustic-ranging-based precise navigation solution for shallow water is designed. Then, the outlier rejection algorithm is introduced by designing a velocity gate. The acoustic-ranging-based navigation is implemented by modifying the long base line solution. To enhance the tracking precision, the outlier rejection algorithm is introduced. The performance of the developed approach is evaluated using experiments. The results demonstrate that precise shallow water depth navigation can be implemented using the suggested approaches.