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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
Journal Basic Information
Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 16, Issue 6 - Dec 2002
Volume 16, Issue 5 - Oct 2002
Volume 16, Issue 4 - Aug 2002
Volume 16, Issue 3 - Jun 2002
Volume 16, Issue 2 - Apr 2002
Volume 16, Issue 1 - Feb 2002
Selecting the target year
Motion and Sloshing Analysis for New Concept of Offshore Storage Unit
Ha, Mun-Keun ; Kim, Mun-Sung ; Paik, Bu-Keun ; Park, Chung-Hum ;
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 1~7
Motion Control of an AUV Using a Neural-Net Based Adaptive Controller
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 8~15
This paper presents a neural net based nonlinear adaptive controller for an autonomous underwater vehicle (AUV). AUV's dynamics are highly nonlinear and their hydrodynamic coefficients vary with different operational conditions, so it is necessary for the high performance control system of an AUV to have the capacities of learning and adapting to the change of the AUV's dynamics. In this paper a linearly parameterized neural network is used to approximate the uncertainties of the AUV's dynamic, and the basis function vector of network is constructed according to th AUV's physical properties. A sliding mode control scheme is introduced to attenuate the effect of the neural network's reconstruction errors and the disturbances in AUV's dynamics. Using Lyapunov theory, the stability of the presented control system is guaranteed as well as the uniformly boundedness of tracking errors and neural network's weights estimation errors. Finally, numerical simulations for motion control of an AUV are performed to illustrate the effectiveness of the proposed techniques.
Diffusion Characteristic of Ocean Dumping Material in the Southeaster Coastal Waters of Korea
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 16~22
The diffusion characteristics of an ocean dumping material in the south-eastern East/Japan Sea related to regulate the physical characteristics with the observation and the hydraulic experiment are investigated. The main results are as follows; (1) Spying CTD observation result of the area of Jung in the East/Japan Sea, the ocean dumping area had influenced the Tsushima Warm Current of high temperature and salinity. Horizontal turbulent diffusivity is 1.913
by drogue tracking. (2) From the experiment of settling, the initial settling velocity of each material is 1.0~2.7 cm/sec according to the specific gravity and initial concentration. In the pycnocline, particles didn't settle under the pycnocline any more and accumulated. It is signified that calculation of the sedimentation rate of the ocean dumping material including of vertical diffusion must be regard the pynocline in the ocean area have well-developed pycnocline. (3) Vertical turbulent diffusivity were 2.219
/sec from the experiment of settling. And, the pycnocline influenced the vertical turbulent diffusivity.
The Numerical Simulation of Harbor Calmness by Finite Element Method
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 22~26
In this paper, a finite element method is applied to the numerical calculation of the harbor calmness. The mild stop equation as the basic equation is used. The key of this model is that the bottom friction and boundary absorption are imposed. A numerical result is presented and compared with the results obtained from the other numerical analysis. These results are in very well agreement. This method calculating the calmness can be broadly utilized making the new design of harbor and fishing port in the future.
A Comparative Study of Ice Scour-Seabed Interaction Models
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 27~35
The interaction of grounded ice ridges with underlying seabed is one of the major considerations in the design of Arctic pipeline system. Previously several ice scour models were developed by researchers to describe the ice scour-seabed interaction mechanism. In view of possible improvements, a comparative study of those ice scour models is performed and their limitation in modeling is discussed. Simple laboratory tests are carried out and then the shape pattern of deposited soil around the ice model is newly defined. Unlike the rectangular idealization of an ice block, in this modified ice scour model, trapezoidal cross sections are assumed to represent the typical shape of an ice ridge based on the field observation data. With the horizontal and vertical motion of ice model, the ice scour depth and soil reacting forces on seabed are calculated with varying the keel angle of an ice ridge.
Ultimate Strength Analysis of Ring-stiffened Cylinders Using Commercial Softwares(II)
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 36~40
Despite the frequent use of ring-stiffened cylinders as a submarine pressure hull or members of various types of offshore structure, their ultimate strength analysis methods have not been well established because of their complex structural characteristics. This paper has established the method how to use commercial softwares based on the finite element method to implement the ultimate strength analysis of ring-stiffened cylinders covering both types of initial imperfection, i.e. initial deformation and initial stress by combining two separately offered functions of common commercial finite element softwares, linear elastic buckling analysis and nonlinear stress analysis. Developed method was applied to one of the world-widely used commercial softwares. ABAQUS for the analysis of ring stiffened cylinders. This paper ends with some useful information about the imperfection sensitivity of ultimate strength ring stiffened cylinders.
Behaviour Characteristic of Grid Dome Shaped Space Structures by Post-tensioning
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 41~45
This paper is concerned with the erection and ultimate load test of dome shaped space structures by post-tensioning. It is a fast and economical method for constructing such a dome by post-tensioning of the cable in bottom chords. This structure consists of uniform pyramids in a flat layouts on the ground, and then the structure is shaped and erected into its final curved space structure. Ultimate load test was performed for dome shaped space structures. The feasibility of the proposed erection method and the reliability of the established geometric model were confirmed with numerical analysis and experimental investigation on a small scale steel model. As a results we can find the most reasonable modeling technique for the prediction of shape formation in practices and we can know the characteristic of the behaviour in ultimate load test for practical design purposes.
A Study on the Effect of Stress Concentration Factor Determined by 3D-ESPI System on the Fatigue Life
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 46~51
Fatigue life estimation by the theoretical stress concentration factors are, in general, considerably different from test results. And in calculating stress concentration factor, it is very difficult to consider actual geometry and material property which are the notch shapes, imperfections or defects of materials such as porosities inclusions and casting defects, etc. Therefore, the paper deals with the experimental method to find out the more exact stress concentration factors by measuring the strain distributions on each specimen by 3D-ESPI(Electronic Speckle Pattern Interferometry) System. Then the fatigue lives are compared between theoretical calculations using stress concentration factors determined by 3D-ESPI system and fatigue test results.
Upheaval Buckling of Offshore Pipelines due to the Transportation of High Pressure and High Temperature Liquid
Hyun-Mo Son ; Si-Young Kim ; Han-Suk Choi ;
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 52~57
Study on HAT Current Generation Rotor
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 58~63
In this research, a design guideline of current generating HAT rotor and acceptable field rotor in offshore environment is proposed. To design HAT rotor model, wind mill rotor design principles and turbine theories were applied based on a field HAT rotor experimental data. To verify the compatibility of the rotor design method and to analyze the properties of design factors, 3 rotor models were designed and experimented in a circular water channel. Three rotor models were designed according to different blade numbers and blade shapes. By changing flow velocity, rotor rpm, the rotor power and efficiency were measured and the properties of rotor were estimated. The results can be effectively applied to the design of current generation rotor.
Development of Digital Carriage for Continuous/Intermittent Welding
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 64~70
This paper shows the results of the development of a small size of digital type continuous and intermittent welding auto-carriage based on microprocessor (Intel 80196KC) for welding process with long welding line. The developed welding auto-carriage loads welding torch and tracks welding line. It is an automaton largely used for welding process with a lot of long welding lines such as shipbuilding and structure. Most traditional auto-carriages have been developed based on analog circuit for open loop control. So this analog circuit welding auto-carriage cannon control welding speed. Specially welding auto-carriage for intermittent welding condition is so complicated and has the low precision of control performance in welding distance and non-welding distance. The auto-carriage developed in this paper has the following characteristics: It has not only functions of traditional carriage but also functions such as pseudo-welding process of big iron structures, intermittent welding in order to limit heat for welding thin plates, crater treatment of the final step of welding, acceleration at the initial step of welding and deceleration in the final step of welding. The main control board of auto-carriage, power supply system and DC motor drive wee developed and manufactured. The welding speed and the welding distance of the developed auto-carriage are controlled accurately by feedback control using photo-sensor. Hardware and software robust against the heat and noise produced on the welding process are developed.
Onshore Deck Mating for Deepwater Nautilus by Super Lift
GAB-REA CHO ;
Journal of Ocean Engineering and Technology, volume 16, issue 1, 2002, Pages 71~75