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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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International Journal of Naval Architecture and Ocean Engineering
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The Society of Naval Architects of Korea
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Volume & Issues
Volume 1, Issue 2 - Dec 2009
Volume 1, Issue 1 - Sep 2009
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Numerical modeling of seawater flow through the flooding system of dry ocks
Najafi-Jilani, A. ; Naghavi, A. ;
International Journal of Naval Architecture and Ocean Engineering, volume 1, issue 2, 2009, Pages 57~63
DOI : 10.3744/JNAOE.2009.1.2.057
Numerical simulations have been carried out on the flooding system of a dry located at the south coasts of Iran. The main goals of seawater flow haracteristics in the intake channels conditions of the flooding system are imposed in the modeling. The upstream boundary condition is the tidal fluctuations of sea water level. At the downstream, the gradually rising water surface elevation in the dry described in a transient boundary condition. The numerical results are compared with available laboratory a good agreement is obtained. The seawater discharge through the flooding system and the required time to filling up the dry dock is determined at the worst case. The water current velocity and pressure on the rigid boundaries are discussed.
Unsteady flow around a two-imensional section of a vertical axis turbine for tidal stream energy conversion
Jung, Hyun-ju ; Lee, Ju-Hyun ; Rhee, Shin-Hyung ; Song, Mu-Seok ; Hyun, Beom-Soo ;
International Journal of Naval Architecture and Ocean Engineering, volume 1, issue 2, 2009, Pages 64~69
DOI : 10.3744/JNAOE.2009.1.2.064
The two-dimensional unsteady flow around a vertical axis turbine for tidal stream energy conversion was investigated using a computational fluid dynamics tool solving the Reynolds-Averaged Navier-Stokes equations. The geometry of the turbine blade section was NACA653-018 aiifoil. The computational analysis was done at several different angles of attack and the results were compared with the corresponding experimental data for validation and calibration. Simulations were then carried out for the two-dimensional cross section of a vertical axis turbine. The simulation results demonstrated the usefulness of the method for the typical unsteady flows around vertical axis turbines. The optimum turbine efficiency was achieved for carefully selected combinations of the number of blades and tip speed ratios.
Research on a simulation-based ship production support system for middle-sized shipbuilding companies
Song, Young-Joo ; Wo, Jong-Hun ; Shin, Jong-Gye ;
International Journal of Naval Architecture and Ocean Engineering, volume 1, issue 2, 2009, Pages 70~77
DOI : 10.3744/JNAOE.2009.1.2.070
Today, many middle-sized shipbuilding companies in Korea are experiencing strong competition from shipbuilding companies in other nations. This competition is particularly affecting small- and middle-sized shipyards, rather than the major shipyards that have their own support systems and development capabilities. The acquisition of techniques that would enable maximization of production efficiency and minimization of the gap between planning and execution would increase the competitiveness of small- and middle-sized Korean shipyards. In this paper, research on a simulation-based support system for ship production management, which can be applied to the shipbuilding processes of middle-sized shipbuilding companies, is presented. The simulation research includes layout optimization, load balancing, work stage operation planning, block logistics, and integrated material management. Each item is integrated into a network system with a value chain that includes all shipbuilding processes.
Development of software for computing forming information using a component based approach
Ko, Kwang-Hee ; Park, Jung-Seo ; Kim, Jung ; Kim, Young-Bum ; Shin, Jong-Gye ;
International Journal of Naval Architecture and Ocean Engineering, volume 1, issue 2, 2009, Pages 78~88
DOI : 10.3744/JNAOE.2009.1.2.078
In shipbuilding industry, the manufacturing technology has advanced at an unprecedented pace for the last decade. As a result, many automatic systems for cutting, welding, etc. have been developed and employed in the manufacturing process and accordingly the productivity has been increased drastically. Despite such improvement in the manufacturing technology, however, development of an automatic system for fabricating a curved hull plate remains at the beginning stage since hardware and software for the automation of the curved hull fabrication process should be developed differently depending on the dimensions of plates, forming methods and manufacturing processes of each shipyard. To deal with this problem, it is necessary to create a "plug-in" framework, which can adopt various kinds of hardware and software to construct a full automatic fabrication system. In this paper, a framework for automatic fabrication of curved hull plates is proposed, which consists of four components and related software. In particular the software module for computing fabrication information is developed by using the ooCBD development methodology, which can interface with other hardware and software with minimum effort. Examples of the proposed framework applied to medium and large shipyards are presented.
OpenFOAM : Open source CFD in research and industry
Jasak, Hrvoje ;
International Journal of Naval Architecture and Ocean Engineering, volume 1, issue 2, 2009, Pages 89~94
DOI : 10.3744/JNAOE.2009.1.2.089
The current focus of development in industrial Computational Fluid Dynamics (CFD) is integration of CFD into Computer-Aided product development, geometrical optimisation, robust design and similar. On the other hand, in CFD research aims to extend the boundaries of practical engineering use in "non-traditional" areas. Requirements of computational flexibility and code integration are contradictory: a change of coding paradigm, with object orientation, library components, equation mimicking is proposed as a way forward. This paper describes OpenFOAM, a C++ object oriented library for Computational Continuum Mechanics (CCM) developed by the author. Efficient and flexible implementation of complex physical models is achieved by mimicking the form of partial differential equation in software, with code functionality provided in library form. Open Source deployment and development model allows the user to achieve desired versatility in physical modeling without the sacrifice of complex geometry support and execution efficiency.
Thermal distortion analysis method for TMCP steel structures using shell element
Ha, Yun-sok ; Rajesh, S.R. ;
International Journal of Naval Architecture and Ocean Engineering, volume 1, issue 2, 2009, Pages 95~100
DOI : 10.3744/JNAOE.2009.1.2.095
As ships become larger, thicker and higher tensile steel plate are used in shipyard. Though special chemical compositions are required for high-tensile steels, recently they are made by the TMCP (Thermo-Mechanical control process) methodology. The increased Yield / Tensile strength of TMCP steels compared to the normalized steel of same composition are induced by suppressing the formation of Ferrite and Pearlite in favor of strong and tough Bainite while being transformed from Austenite. But this Bainite phase could be vanished by another additional thermal cycle like welding and heating. As thermal deformations are deeply related by yield stress of material, the study for prediction of plate deformation by heating should niflect the principle of TMCP steels. The present study is related to the development of an algorithm which could calculate inherent strain. In this algorithm, not only the mechanical principles of thermal deformations, but also the initial portion of Bainite is considered when calculating inherent strain. Distortion analysis results by these values showed good agreements with experimental results for normalized steels and TMCP steels during welding and heating. This algorithm has also been used to create an inherent strain database of steels in Class rule.
Cross flow response of a cylindrical structure under local shear flow
Kim, Yoo-Chul ; Rheem, Chang-Kyu ;
International Journal of Naval Architecture and Ocean Engineering, volume 1, issue 2, 2009, Pages 101~107
DOI : 10.3744/JNAOE.2009.1.2.101
The VIV (Vortex-Induced Vibration) analysis of a flexible cylindrical structure under locally strong shear flow is presented. The model is made of Teflon and has 9.5m length, 0.0127m diameter, and 0.001m wall thickness. 11 2-dimensional accelerometers are installed along the model. The experiment has been conducted at the ocean engineering basin in the University of Tokyo in which uniform current can be generated. The model is installed at about 30 degree of slope and submerged by almost overall length. Local shear flow is made by superposing uniform current and accelerated flow generated by an impeller. The results of frequency and modal analysis are presented.