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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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Korean Society of Ocean Engineers
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Volume & Issues
Volume 27, Issue 6 - Dec 2013
Volume 27, Issue 5 - Oct 2013
Volume 27, Issue 4 - Aug 2013
Volume 27, Issue 3 - Jun 2013
Volume 27, Issue 2 - Apr 2013
Volume 27, Issue 1 - Feb 2013
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Three-Dimensional Grillage Analysis of Reaction Forces on Supports of Pre-Erection Block
Ryu, Cheolho ; Kim, Sungchan ; Kim, Dong Geun ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 1~8
DOI : 10.5574/KSOE.2013.27.4.001
Many PE (pre-erection) blocks are supported by wooden, concrete, or steel supports when they are stocked in the outdoor areas of a shipyard. Their positions and numbers are planned on the basis of the workers' experience. Recently, many shipyards have been making PE blocks with various shapes and weight distributions because of the variety of ships and building technologies. Therefore, it is now necessary to deal with blocks that they have no experience with. We propose a method to conveniently and quickly evaluate the structural safety of PE block supports, without the need for special knowledge and technology related to structural analysis. This method can reduce the large number of man hours (MH) normally needed for the analysis. The three-dimensional grillage analysis is performed for a simplified grillage model of a PE block. For efficiency, the grillage model of the PE block is automatically built from its three-dimensional CAD model, and its weight is also automatically distributed on the grillage model. The integrated system has been comprehensively implemented to perform the grillage analysis for the reaction forces on block supports. This paper describes how to make a grillage model of a PE block and estimate the weight distribution of the block on this grillage model. These steps are verified by comparing the supports reaction forces to those of the 3D finite element analysis for the PE blocks that are provided by a shipyard.
Tensile Properties of High Mn Austenitic Stainless Steel with Two Phases of Martensite and Austenite
Kim, Young-Hwa ; Kang, Chang-Yong ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 9~13
DOI : 10.5574/KSOE.2013.27.4.009
The tensile properties of high manganese austenitic stainless steel with the two phase structures of deformation-induced martensite and reversed austenite were studied. Reversed austenite with an ultra-fine grain size of less than
was obtained by reversion treatment. The two phases structures of deformation-induced martensite and reversed austenite were obtained by an annealing treatment in the range of
for various times in 70% cold- rolled high-manganese austenitic stainless steel. The volume fraction of the reversed austenite increased rapidly with increases in the annealing temperature and time. In the stainless steel with the two phases of austenite and martensite, the strength decreased rapidly, while the elongation increased slowly and then rapidly increased with an increase in the volume fraction of the reversed austenite. Therefore, the strength and elongation were strongly controlled by the volume fraction of reversed austenite. A good combination of high strength and elongation could be obtained by the mixed structure of reversed austenite and deformation-induced martensite.
Application of 3-D Numerical Method (LES-WASS-3D) to Estimation of Nearshore Current at Songdo Beach with Submerged Breakwaters
Hur, Dong-Soo ; Lee, Woo-Dong ; Kim, Myoung-Kyu ; Yoon, Jong-Sung ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 14~21
DOI : 10.5574/KSOE.2013.27.4.014
This study examined the field application of a 3-D numerical model (LES-WASS-3D) to the estimation of the nearshore current at Songdo beach, Busan. The wave and tide conditions observed at Songdo beach during Typhoon Ewiniar (July 10, 2006) were used in a numerical simulation. The numerical wave heights were in good agreement with the field data. The spatial distributions of the wave heights, mean water levels, and mean flows obtained from the numerical simulation are discussed in relation to the bottom topographical change near Songdo beach before and after Typhoon Ewiniar. The results revealed that LES-WASS-3D is a powerful tool for estimating the nearshore current in the field.
Study on Effective Arrangement of Mooring Lines of Floating-Type Combined Renewable Energy Platform
Choung, Joonmo ; Jeon, Gi-Young ; Kim, Yooil ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 22~32
DOI : 10.5574/KSOE.2013.27.4.022
This paper presents the conceptual design procedure for the taut-leg mooring lines of a floating-type combined renewable energy platform. The basic configuration of the platform is determined based on an understanding of floating offshore plants. The main dimensions and mass distribution are determined based on a hydrostatic calculation. To identify the motion history of the floating platform and the tension history of the mooring lines, a hydrodynamic analysis is executed using Ansys.Aqwa. This helps in the selection of the best configuration for the mooring system such as the number of mooring lines, wire types, anchored positions, etc. In addition, the fatigue life of the mooring lines can be predicted from the tension history using the rain-flow cycle counting method.
Study on Development of Surge-Tide-Wave Coupling Numerical Model for Storm Surge Prediction
Park, Jong-Kil ; Kim, Myung-Kyu ; Kim, Dong-Cheol ; Yoon, Jong-Sung ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 33~44
DOI : 10.5574/KSOE.2013.27.4.033
IIn this study, a wave-surge-tide coupling numerical model was developed to consider nonlinear interaction. Then, this model was applied and calculations were made for a storm surge on the southeast coast. The southeast coast was damaged by typhoon "Maemi" in 2003. In this study, we used a nearshore wind wave model called SWAN (Simulating WAves Nearshore). In addition, the Meyer model was used for the typhoon model, along with an ocean circulation model called POM (Princeton Ocean Model). The wave-surge-tide coupling numerical model could calculate exact parameters when each model was changed to consider the nonlinear interaction.
Strength Characteristics of FRP Composite Materials for Ship Structure
Choi, Han-Kyu ; Nam, Ki-Woo ; Ahn, Seok-Hwan ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 45~54
DOI : 10.5574/KSOE.2013.27.4.045
In this study, various types of composite materials and adhesives that are actually used in the shipbuilding field for small ships, leisure boats, and fishing boats were applied in the hand lay-up method and vacuum infusion method to manufacture specimens. Then the tensile strength, tensile modulus, flexural strength, and flexural modulus values of these specimens were obtained. In addition, the barcol hardness and fiber content were obtained from the specimens. The results showed that the strengths of the specimens manufactured using the vacuum infusion method were higher than those manufactured using the hand lay-up method. Moreover, the barcol hardness and fiber content were also higher in those manufactured using the vacuum infusion method. The specimens manufactured using the vacuum infusion method were thinner despite their large fiber content.
Wave Run-up Characteristics of Ocean Wave, Current, and Kelvin Wave Interaction in the Canal
Hur, Dong-Soo ; Lee, Woo-Dong ; Jung, Kwang Hyo ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 55~61
DOI : 10.5574/KSOE.2013.27.4.055
The numerical simulation using LES-WASS-3D is developed to investigate the wave run-up on the revetment along the canal. Interaction of ocean wave, current, and Kelvin wave is investigated on 40 conditions varying the number of ship, cruising direction, and relative cruising location of ships, when a 650TEU container cruises in the canal. The mean wave run-up heights on the revetment are compared for every simulated conditions. The largest height of wave run-up is generated at the C-pair condition and the wave run-up generated at the canal entrance is larger than that at the inside canal. When Kelvin waves is interacted with the current, the mean wave run-up height is increased approximate 10% compared with no current condition.
Study on Wave Run-Up Phenomenon over Vertical Cylinder
Lee, Sang Beom ; Han, Seung Yoon ; Choi, Young Myoung ; Kwon, Sun Hong ; Jung, Dong Woo ; Park, Jun Soo ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 62~67
DOI : 10.5574/KSOE.2013.27.4.062
In this paper, the wave run.up on a vertical cylinder is presented. Various cross sections of a cylinder were simulated using the panel method for various wave periods. Two.dimensional model tests were performed in a wave flume. The simulation results are compared with the test results. The simulation is based on the linear diffraction theory.
Investigation of Characteristics of Waves Generated in Two-Dimensional Wave Channel
Ahn, Jae-Youl ; Choi, Jung-Kyu ; Kim, Hyoung-Tae ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 68~75
DOI : 10.5574/KSOE.2013.27.4.068
This paper investigates the characteristics of waves generated by a flap-type wave maker in a two-dimensional wave channel. Measurements are carried out for various water depths, wave heights, periods, and lengths capacitance-type wave height gages. The experimental results are shown to satisfy the dispersion relation of the linear wave theory. For waves with a small height and long period, the wave profiles agree well with those of the linear wave theory. However, as the wave height and period become higher and shorter, respectively, it is shown that the wave profiles measured in the present experiments are different from the linear wave profiles, and the measured wave heights are smaller than the target wave heights, which may be due to the non-linearity of the waves. As the wave progresses toward the channel end, the wave height gradually decreases. This reduction in the wave height along the wave channel is explained by the wave energy dissipation due to the friction of the side walls of the channel. The performance of the wave absorber in the channel is found to be acceptable from the results of the wave reflection tests.
Model Test for Heave Motion Reduction of a Circular Cylinder by a Damping Plate
Koh, Hyeok-Jun ; Kim, Jeong-Rok ; Cho, Il-Hyoung ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 76~82
DOI : 10.5574/KSOE.2013.27.4.076
Motion reduction of an offshore structure at resonant frequency is essential for avoiding critical damage to the topside and mooring system. A damping plate has a distinct advantage in reducing the motion of a floating structure by increasing the added mass and the damping coefficient. In this study, the heave motion responses of a circular cylinder with an impermeable and a permeable damping plate attached at the bottom of the cylinder were investigated thru a model test. The viscous damping coefficients for various combinations of porosity were obtained from a free-decay test by determining the ratio between any pair of successive amplitudes. Maximum energy dissipation occurred at a porous plate with a porosity P = 0.1008. Experimental results for regular and irregular waves were compared with an analytical solution by Cho (2011). The measured heave RAO and spectrum reasonably followed the trends of the predicted values. A significant motion reduction at resonant frequency was pronounced and the heaving-motion energy calculated by the integration of the area under the heave motion spectrum was reduced by more than 75% by the damping plate. However, additional energy dissipation by eddies of strong vorticity and flow separation inside a porous damping plate was not found in the present experiments.
Dynamic Response Analysis of Top-tensioned Riser Under Sheared Current Load
Kim, Kookhyun ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 83~89
DOI : 10.5574/KSOE.2013.27.4.083
A numerical scheme based on a mode superposition method is presented for the dynamic response analysis of a top-tensioned riser (TTR) under sheared current loads. The natural frequencies and mode shapes of the TTR have been calculated analytically for a beam with a slowly varying tension and pinned-pinned boundary conditions at the top and bottom ends. The lift coefficients and corresponding amplitudes used to estimate the vortex-induced modal force and damping for each mode were predicted via iterative calculations based on the input and output power balancing concept. Here, the power-in regions were controlled by the normal distribution function, for which the center was coincident with the lock -in location by local vortex-shedding, and the range was defined by the constant standard deviation for the reduced velocity by the local current speed. Finally, dynamic responses such as root-mean-squared displacement and stress were calculated using the mode superposition technique. In order to verify the presented scheme, a numerical calculation was performed for a TTR under an arbitrary linearly sheared current and linearly varying tension. A comparison with the results of the existing software showed that the presented scheme could give reliable and feasible solutions. Case studies were performed to investigate the effects of various current loads and tensions.
2-Dimensional Moving Particle Simulation for Prediction of Oil Boom Performance in Waves
Nam, Jung-Woo ; Park, Ji-In ; Hwang, Sung-Chul ; Park, Jong-Chun ; Jeong, Se-Min ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 90~97
DOI : 10.5574/KSOE.2013.27.4.090
Oil booms are one of the most widely used types of equipment for the protection of coastal areas against oil spills. In some situations, however, there are several types of oil leaks from the oil boom. Important factors regarding these phenomena include the surrounding ocean environment, such as waves, the density and viscosity of oil, the length of the oil boom skirt, etc. To estimate the performance of the oil boom, it is necessary to predict the behavior of the spilled oil and oil boom. In the present study, the prediction of oil boom performance in waves was carried out using the Pusan-National-University-modified Moving Particle Semi-implicit (PNU-MPS) method, which is an improved version of the original MPS proposed by Koshizuka and Oka (1996). The governing equations, which consist of continuity and Navier-Stokes equations, are solved by Lagrangian moving particles, and all terms expressed by differential operators in the governing equations are replaced by the particle interaction models based on a kernel function. The simulation results were validated through a comparison with the results of Violeau et al. (2007)..
Seismic Fragility for 5MW Offshore Wind Turbine using Pushover Analysis
Lee, Sang-Geun ; Kim, Dong-Hyawn ; Yoon, Gil-Lim ;
Journal of Ocean Engineering and Technology, volume 27, issue 4, 2013, Pages 98~106
DOI : 10.5574/KSOE.2013.27.4.098
Seismic fragility curves for an offshore wind-turbine structure were obtained. The dynamic response of an offshore wind turbine was analyzed by considering the nonlinear behavior of layered soil and the added mass effect due to seawater. A pile-soil interaction effect was considered by using nonlinear p-y, t-z curves. In the analysis, the amplification effect of ground acceleration through layered soil was considered by applying ground motion to each of the soil layers. The vertical variation in ground motion was found by one-dimensional free-field analysis of ground soils. Fragility curves were determined by damage levels in terms of tower stress and nacelle displacements that were found from static pushover analysis of the wind-turbine structure.