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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
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Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 20, Issue 6 - Dec 2006
Volume 20, Issue 5 - Oct 2006
Volume 20, Issue 4 - Aug 2006
Volume 20, Issue 3 - Jun 2006
Volume 20, Issue 2 - Apr 2006
Volume 20, Issue 1 - Feb 2006
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Review of Offshore Industry and Engineering Development
Lee, Seung-Keon ; Choi, Han-Suk ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 1~8
This paper introduces a review and literature study of offshore engineering and constructions from 1920s to 2000s. The study was focused on the literature survey and the history of Brawn & Root and J. Ray McDermott in the Gulf of Mexico and other offshore areas. The fluctuations of oil and gas prices have been strongly influenced the development of offshore industry since its very beginning. Scientific projects on the space and under the earth had played very important roles in offshore development in 1950s and 1960s. Deepwater developmentshave been influenced by the computer assisted analysis and design in 1970s and 1980s. Innovative technology provided continuous developments of deepwater structures in 1990 and after.
Development of a Wave Absorbing System Using a Liquefied Sandbed
Kang, Yoon-Koo ; Takahashi, Shigeo ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 9~16
A new wave-absorbing system, called the liquefied sandbed wave barrier (LSWB) system, is currently under development at the Port and Airport Research Institute (PARI) of Japan. The wave damping effect by the LSWB system is substantial, as confirmed by small-scale experiments and FEM numerical calculations, i.e., the wave transmission coefficient of the system is less than 0.2. Here, the results of large-scale experiments arediscussed in view of practical application. Although the LSWB system provides high wave damping, nearly equal to theoretical values, difficulty exists in obtaining a homogeneously liquefied sandbed, due to the occurrence of liquefied sandbed compaction by cyclic wave loading, which in turn, reduces excess pare pressure and the wave damping effect. These two phenomena primarily occur when the sandbed is composed of fine sand with small permeability. Based on experimental results, we propose a design method that includes countermeasures against such problems, and a prototype LSWB system is constructed in a very large wave flume at PARI. Wave damping by the prototype LSWB system is confirmed to be quite stable and high, as predicted by theoretical calculations.
Deformation and Fracture Behavior of Wall Thinned Carbon Steel Pipes
Ahn, Seok-Hwan ; Nam, Ki-Woo ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 17~23
Monotonic four-point bending tests were conducted on straight pipe specimens, 102 mm in diameter with local wall thinning, in order to investigate the effects of the depth, shape, and location of wall thinning on the deformation and failure behavior of pipes. The local wall thinning simulated natural erosion/corrosion metal loss. The deformation and fracture behavior of the straight pipes with local wall thinning was compared with that of non wall-thinning pipes. The failure modes were classifiedas local buckling, ovalization, or crack initiation, depending on the depth, shape, and location of the local wall thinning. Three-dimensional elasto-plastic analyses were carried out using the finite element method. The deformation and failure behavior, simulated by finite element analyses, coincided with the experimental results.
Application of Neural Network to the Estimation of Curvature Deformation of Steel Plates in Line Heating
Jeon, Byung-Jae ; Kim, Hyun-Jun ; Yang, Park-Dal-Chi ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 24~30
Different methods exist for the estimation of thermaldeformation of plates in the line heating process. These are based on the assumption of residual strains in the heat-affected zone, known as the method of inherent strains, or simulated relations between heating conditions and residual deformations. The purpose of this paper is to develop a simulator of thermal deformation in the line heating, using the artificial neural network. Curvature deformations for the plate-forming are investigated, which can be used as a prime deformation parameter in the process. The curvature of plates are calculated using the approximation of plate surface by NURBS. Line heating experiments for 11 specimens of different thickness and heating conditions were performed. Two neural networks predicting the maximum temperature and curvature deformations at the heating line are studied. It was concluded that the thermal deformations predicted by the neural network can be used in a line heating simulator, which is considered an attractive and practical alternative to the existing methods.
Study on High Accurate Schemes for Simulation of Free-surface Flow
Park, Jong-Chun ; Lee, Byoung-Hyuk ; Kim, Jeung-Hu ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 31~36
Numerical schemes for spacing and time are tested to accurately simulate the wave propagation. The tested numerical schemesinclude 2nd-order central differencing, l-order upwind scheme, 2nd-order Leith scheme, 3rd-order MUSCLE, QUICK and QUICKEST schemes in spacing and the Euler and 4th-order Runge-Kutta(R-K) schemes in time. It is seen that more accurate results are expected when the higher-order schemes, especially the schemes combined with a TVD control limiter, are used for solving the wave equation. The 3rd-order upwind scheme with limiter and the 4th-order R-K scheme in tim￡ are finally applied to the wave-making simulation in a digital wave tank.
An Experimental Study on Steering Performance of Tracked Vehicle on Deep-sea Cohesive Soft Soil by DOE using Orthogonal Arrays
Choi, Jong-Su ; Hong, Sup ; Kim, Hyung-Woo ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 37~42
This paper is concerned with experimental investigation of steering performance of a tracked vehicle on extremely soft soil. A tracked vehicle model with principal dimensions of 0.9 m(L)x0.75 m(B)x0.4 m(H) and weight of 167 kg was constructed with a pair of driving chain links, driven by two AC-servo motors. The tracks were configured with detachable grousers with variable span. A deep seabed was simulated by means of a bentonite-water mixture in a soil bin of 6.0 m(L)x3.7 m(B)x0.7 m(H). The turning radii of vehicle and driving torques of motors were measured with respect to experiment variables: steering ratio, driving speed, grouser chevron angle, grouser span, and grouser height. L8 orthogonal table is adopted for DOE (Design of experiment). The effects of experiment variables on steering performance are evaluated.
Experimental Study on the Stability of Dredged Soil Bed under Cyclic Wave Actions
Kang, Yoon-Koo ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 43~49
Detailed investigations were carried out on the stability of the dredged soil bed against wave actions, aimedat establishing the design method of artificial tidal flats using dredged soil. The soil was dredged at Nagoya port, Japan, and has a mean grain size of 0.013mm. Basic features of artificial dredged soil bed against wave actions were explained from a series of model experiments in a wave flume. The two types of section shapes were employed; one is a horizontal bed and the other is a sloped one. Changes of the bed profile, shear strength, grain size distribution and water content, according to the wave actions, were measured in detail. The cumulative effect of the wave actions, over about one week, was investigated. A dredged soil bed moves withthe wave actions with relatively small wave height. It should be especially. noted that the clay component is dissolved and flown out, away from the surface layer, and consequently the surface layer hardens, as if it is covered with sand. Wren the wave height is gradually increased, the bed is not liquefied and the shear strength of the dredged bed is increased by a wave-induced dissipation of pore pressures in the bed and a decrease of clay component by the wave-induced leakage.
Three-dimensional Mixing Behaviour Characteristics of Seomjin River Discharges
Kim, Jong-Kyu ; Kim, Myong-Won ; Kang, Tae-Soon ; Yoon, Eun-Chan ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 50~57
The effect of discharges from the Seomjin River on the dispersion of thermal effluent from the Hadong Power Plant, located along the south coast of Korea, was investigatedusing intensive field observation and three-dimensinal Princeton Ocean Model simulations. A POM and observed CTD data was used to predict the mixing behaviour of the Summer freshet, during the July 2005 intensive observing period. The dispersal of the river discharge anomaly, associated with the Seomjin River plume, was seen to be highly responsive to tidal currents and river flows during the spring tide.
Numerical Assessment for Coastal Water Purification Utilizing a Tidal Jet System
Park, Jong-Chun ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 58~63
When the costal zone surrounded by a breakwater has a narrow vertical opening, currents in the vicinity of a narrow entrance can result in a jet flow, coinciding with the tide. Such a Tidal-Jet Generator(TJG) can change the water mass distribution and transport processes in the domain of influence of the jet. Also, it can decrease the residual time of them. In the present study, the water purification utilizing tidal jets in the coastal zone over constant bathymetry are estimated numerically, using a finite-difference numerical scheme, named the NS-MAC-TIDE method, which isbased on the fully 3D Navier-stokes(NS) equations. The shear velocity near the inlet of the TJG are predicted from the flow field simulation, and are assessed qualitatively with the development of scouring or sediment that is caused by the change of diffusion or sweeping flowup from the seabed of sediment particles. Finally, through solving a transport equation of concentration, the residual time related on mass transport processes and the flushing mechanism for water purification are investigated.
Numerical Analysis on Wave Energy Absorption of OWC-type Wave Power Generation
Kyoung, Jo-Hyun ; Hong, Sa-Young ; Hong, Do-Chun ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 64~69
A numerical analysis is made to investigate the wave absorption efficiency of a OWC-type wave power generator. Energy absorption by an OWC(Oscillating Water Column) air-chamber is computed in regular waves, taking account of the oscillating surface-pressure, due to pressure drop, across the duct of the air chamber. The problem is formulated in the scope of potential theory and solved by the Localized Finite Element Method(LFEM), based on the classical variational principle. The efficiency of energy absorption is investigated by. changing wave conditions, sea-bottom slope and pressure drop coefficient.
Effects of the Multi-directional Irregular Waves on the Motion Responses and Tension Variations of ISSC-TLP
Lee, Chang-Ho ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 70~75
A numerical procedure is described for estimating the effects of the multi-directional irregular waves on the motion responses and tension variations of the ISSC-TLP. The numerical approach is based on a three-dimensional source distribution method and a spectral analysis technique of directional waves. The spectral description for the linear system of ISSC-TLP in the frequency domain is sufficient to completely define the motion responses and tension variations. This is because both the wave inputs and responses are stationary Gaussian random processes, of which the statistical properties in the amplitude domain are well known. The numerical results for the linear motion responses and tension variations in regular waves are compared with the experimental and numerical ones, which are obtained in the literature. The results of comparison confirmed the validity of the proposed approach.
Large Eddy Simulation of Turbulent Flow around a Ship Model Using Message Passing Interface
Choi, Hee-Jong ; Yoon, Hyun-Sik ; Chun, Ho-Hwan ; Kang, Dae-Hwan ; Park, Jong-Chun ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 76~82
The large-eddy simulation(LES) technique, based an a message passing interface method(MPI), was applied to investigate the turbulent flaw phenomena around a ship. The Smagorinski model was used in the present LES simulation to simulate the turbulent flaw around a ship. The SPMD(sidsngle program multiple data) technique was used for parallelization of the program using MPI. All computations were performed an a 24-node PC cluster parallel machine, composed of 2.6 GHz CPU, which had been installed in the Advanced Ship Engineering Research Center(ASERC). Numerical simulations were performed for the Wigley hull, and the Series 60 hull(CB=0.6) using 1/4-, 1/2-, 1- and 2-million grid systems and the computational results had been compared to the experimental ones.
Hydroelastic Behavior for a Very Lagre Floating Structure of Poontoon-Type in Multi-Directional Irregular Waves
Kim, Chel-Hyun ; Jo, Hyo-Jae ; Lee, Seung-Chul ; Goo, Ja-Sam ;
Journal of Ocean Engineering and Technology, volume 20, issue 4, 2006, Pages 83~90
Recently, as the technology of utilization for the ocean space is being advanced, floating structures are asked for being mare and mare huge-scale. A very large floating structure(VLFS) is considered as a flexible structure, because of a quite large length-to-breadth ratio and its geometrical flexibility. The main object of this study is to develop an accurate and convenient method on the hydroelastic response analysis of very large offshore structures on the real sea states. The numerical approach for the hydorelastic responses is based on the combination of the three dimensional source distribution methods, the dynamic response analysis method and the spectral analysis method. A model is considered as many rigid bodies connected elastic beam elements. The calculated results shaw good agreement with the experimental and calculated ones by Ohta.