International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
Korean Society of Ocean Engineers
- Annual
- /
- 1229-1668(pISSN)
Domain
- Construction/Transportation > Maritime Safety/Transportation Technology
- Construction/Transportation > Water Engineering System
Volume 3 Issue 1
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A new alternative for large deepwater field development is described. This "Oil Box" (aka "Box Spar") is a multifunction vessel capable of floating drilling, production, storage and offloading (FDPSO). It is distinguished from other Floating Production, Storage and Offloading (FPSO) vessels by its unique hull form and oil storage system. It's main advantages are flexibility derived from the floatover deck option, use of proven top tensioned riser technology, and motion characteristics which make it operable in a wide range of environmental conditions.
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The singularity system to represent two circular cylinders poised under different ambient flow fields is considered in the present research. The singularity system, being composed of a series of singularities, has to be truncated for numerical calculations. A rational criterion to determine how many terms of this series should be retained to maintain the prescribed accuracy is provided through analysis of the converging property of the series. A particular emphasis is put to how to deal with the discrete vortex model of a boundary layer, this possibility being the basis for the development of a tool to simulate vortex shedding from a structure composed of two circular cylinders. The principle to obtain the present singularity system can be applied to more-than-cylinders structure. Only th series become much more complex with increase of the number of cylinders.
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The improved Green integral equation for the calculation of time-harmonic potentials in the radiation diffraction problem about a freely floating body in the presence of moderate or weak current is presented. The forward-speed Green function presented by Brard is used. The correct free surface boundary conditions on the physical free surface are employed as well as an appropriate boundary conditions on the non-physical inner free surface. The default in the existing Green integral equation as well as in the source integral equation is discussed in detail.
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A numerical investigation was made to examine characteristics of rectangular pontoon type floating breakwaters in oblique waves. Sway and heave wave exciting forces, roll moment acting on the floating breakwater and three motion reponses decrease as the incident wave angle increases for the most of the wave ranges. There exists a minimum wave transmission coefficient which is a function of wave frequency. In short wave range wave transmission coefficient increases as the incident wave angle increases. In long wave range, however, wave transmission coefficient decreases as the wave incident angle increases.
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This paper proposes a long-term prediction of offshore structures in ocean waves. All short-term statistics is generated by the simulation for all the combinations of significant wave heights and spectral peak periods. The simulation has been tested first on linear system, whose analytic solution is known, to verify if the simulation works accurately. Then the scheme was applied to the nonlinear system. This paper demonstrated that the proposed scheme could be an efficient tool in estimating the response of offshore structures.
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The present study dealt with the relationships among the interfacial shear strength, the thickness of interfacial reaction layer and the impact value of
$Nb/MoSi_2$ laminate composites. In addition, the tensile test was conducted to evaluate the fracture strain of$Nb/MoSi_2$ laminate composites. To change the thickness of the reaction layer,$Nb/MoSi_2$ laminate composites alternating sintered MoSi2 layers and Nb foils were fabricated as the parameter of hot press temperature. It has been found that the growth of the reaction layer increases the interfacial shear strength and decreases the impact value by localizing a plastic deformation of Nb foil. There also exist appropriate shear strength and the thickness of the reaction layer, which are capable of maximizing the fracture energy of$Nb/MoSi_2$ . -
The term "deep holes" is used to describe the machining of holes with a relatively large length to diameter ratio. The main feature of BTA deep hole drilling is the stabilization of cutting force necessary for the self guidance of the drill head. An additional feature is the cutting tool edges that are unsymmetrically placed on the drill head. There is an increasing necessity to predict the hole geometry and other dynamic stability behavior of deep hole drilling guidance. In this study, the effects of BTA deep hole drilling conditions on the hole profile machined piece are analyzed using domain analysis technique. The profile of deep hole drilled work piece is related to cutting speed, feed rate, chip flow, tool wear, and so on. This study deals with the experimental results obtained during the BTA drilling on SM45C, SM55C carbon steels and SCM440 steels under various cutting conditions, and these results are compared with analytical evaluations.aluations.
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Improvement was made on the free span analysis of the offshore pipelines. The effect of axial force (both tension and compressive force) can be explicitly applied to the current design code. The closed form solutions of beam-column equation were derived for the typical boundary conditions. The solutions can be used to find the natural frequencies of the span using the energy balance concept. The results can be applied to the current design code and will result more realistic calculation of free span lengths of offshore pipelines.
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The trends of recent passenger ships are becoming speedy and luxury style to enhance comfortableness in cabin. In order to meet these trend, ship designer has to improve the sound quality as well as to reduce the sound pressure level in cabins. In this paper, the trend of noise and sound quality of real high-speed coastal passenger ships are measured and analyzed, while running on their regular courses. The sound quality parameters such as loudness, roughness, fluctuation strength, and sharpness are evaluated by Zwicker loudness calculation. In addition, we try to find sensitive critical frequency band for the improving sound quality by using signal editing. Finally, the expected effective design methods are proposed to designer for the improving sound quality of passenger ships.