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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 17, Issue 6 - Dec 2003
Volume 17, Issue 5 - Oct 2003
Volume 17, Issue 4 - Aug 2003
Volume 17, Issue 3 - Jun 2003
Volume 17, Issue 2 - Apr 2003
Volume 17, Issue 1 - Feb 2003
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Energy Dissipation and Transfer among Wave Components during Directional Breaking Processes
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 1~6
Wave energy dissipation and energy transfer between wave components, during the directional wave breakings, are investigated. Directional incipient and plunging breakers were generated by focusing the multi-frequency and multi-directional wave components at a designed location, based on a constant wave amplitude and a constant wave steepness frequency spectrum. The time series of surface wave elevation was measured at 9 different locations around the wave focusing point, using a wave gauge array. In order to examine the variation of the directional spreading function, the horizontal velocity of fluid motion was also measured. By comparing energy spectrums, before and after the breaking, the characteristics of energy dissipation and energy transfer, caused by wave breaking, are investigated. Their dependencies on directionality, as well as frequency, are analyzed. The breakings significantly dissipate wave energy, through energy transfer, in the upper region of the peak-frequency band, while enhancing wave energy in the low-frequency band.
Numerical Simulation of a Near shore Tsunami Using a Digital Wave Tank Simulation Technique
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 7~15
A Digital Wave Tank simulation technique, based on a finite-difference method and a modified marker-and-cell (MAC) algorithm, is applied in order to investigate the characteristics of nonlinear Tsunami propagations and their interactions with a 2D sloping beach, Ohkushiri Island, and to predict maximum wove run-up around the island. The Navier-Stokes (NS) and continuity equation are governed in the computational domain, and the boundary values are updated at each time step, by a finite-difference time-marching scheme in the frame of the rectangular coordinate system. The fully nonlinear, kinematic, free-surface condition is satisfied by the modified marker-density function technique. The near shore Tsunami is assumed to be a solitary wave, and is generated from the numerical wave-maker in the developed Digital Wave Tank. The simulation results are compared with the experiments and other numerical methods, based on the shallow-water wave theory.
A Study of the Economic Design of Rubble Mould Breakwaters Using ADS(Automated Design Synthesis) Optimization Program
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 16~22
In this paper, the method of determining the economically-optimal design section of rubble mound breakwater, using ADS program, was studied to supplement the deterministic approach. First of all, the design waves are computed, according to the return periods, using the Weibull distribution from the data of waves at the location of the breakwater. In order to take an optimal section, according to the return periods, the ADS program was used. The restriction conditions and objective functions are decided from the references of the specifications and standard manuals for Coastal and Harbor Construction Work. Results from this study support the ADS program as an appropriate method for determining the economically-optimal section of rubble mound breakwater, comparing the construction costs and the initial and damage repair costs for its life time.
Optimal Design of Rubble Mound Breakwater Used by Partial Safety Factor Method
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 23~31
As there are so many uncertainties associated with using the determinism analysis method in the design of rubble mound breakwater, it is impossible for a designed construction to provide ultimate stability. First of all, due to the uncertainty of Load and Resistance, a safety level concerning the destruction mode of construction must be given. Then, the optimization design should be processed. After all, we can say that it is a more reasonable design method than the design used by the stability rate. In this study, an established design process is accomplished using Hudson's equation and an economic analysis with the breakwater's section is also conducted. Hudson's equation is compared to Van der Meer's equation. These results are utilized to drop a damage rate, increase the stability of construction, and determine the optimization section of the breakwater.
Computation of Non-Linear Wave Height Distribution in the Seogwipo Harbor Using Finite Element Method
Kim, Nam-Hyeong ; Hur, Young-Teck ; Young, Yin-Lu ;
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 32~37
In this paper, finite element method is applied for the numerical analysis of wave height distribution. The mild-slope equation is used as the basic equation. The key of this model is to impose the effect of nonlinear waves. Numerical results are presented and agreed well with the results from experimental measurements and other numerical analysis. The present method to determine wave height distribution can be broadly utilized for the analysis of new harbor and port designs in the future.
Optimum Design of Sandwich Panel Using Hybrid Metaheuristics Approach
Kim, Yun-Young ; Cho, Min-Cheol ; Park, Je-Woong ; Gotoh, Koji ; Toyosada, Masahiro ;
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 38~46
Aim of this article is to propose Micro-Genetic Simulated Annealing (
) as a hybrid metaheuristics approach to find the global optimum of nonlinear optimisation problems. This approach combines the features of modern metaheuristics such as micro-genetic algorithm (
) and simulated annealing (SA) with the general robustness of parallel exploration and asymptotic convergence, respectively. Therefore,
approach can help in avoiding the premature convergence and can search for better global solution, because of its wide spread applicability, global perspective and inherent parallelism. For the superior performance of the
, the five well-know benchmark test functions that were tested and compared with the two global optimisation approaches: scatter search (SS) and hybrid scatter genetic tabu (HSGT) approach. A practical application to structural sandwich panel is also examined by optimism the weight function. From the simulation results, it has been concluded that the proposed
approach is an effective optimisation tool for soloing continuous nonlinear global optimisation problems in suitable computational time frame.
A Study on the Dynamic Behavior of a Simply Supported Beam with Moving Masses and Cracks
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 47~52
To determine the effect of transverse open crack on the dynamic behavior of simply-supported Euler-Bernoulli beam with the moving masses, an iterative modal analysis approach is developed. The influence of depth and position of the crack in the beam, on the dynamic behavior of the simply supported beam system, have been studied by numerical method. The cracked section is represented by a local flexibility matrix, connecting two undamaged beam segments that is, the crack is modeled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces across the crack section, and is derived by applying a fundamental fracture mechanics theory. As the depth of the crack is increased, the mid-span deflection of the simply-supported beam, with the moving mass, is increased. The crack is positioned in the middle point of the pipe, and the mid-span defection of the simply-supported pipe represents maximum deflection.
Optimum Design of Trusses Using Genetic Algorithms
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 53~57
Optimum design of most structural system requires that design variables are regarded as discrete quantities. This paper presents the use of Genetic Algorithm for determining the optimum design for truss with discrete variables. Genetic Algorithm are know as heuristic search algorithms, and are effective global search methods for discrete optimization. In this paper, Elitism and the method of conferring penalty parameters in the design variables, in order to achieve improved fitness in the reproduction process, is used in the Genetic Algorithm. A 10-Bar plane truss and a 25-Bar space truss are used for discrete optimization. These structures are designed for stress and displacement constraints, but buckling is not considered. In particular, we obtain continuous solution using Genetic Algorithms for a 10-bar truss, compared with other results. The effectiveness of Genetic Algorithms for global optimization is demonstrated through two truss examples.
Modal Characteristics of Steel Plate-Girder Under Various Temperatures
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 58~64
The performance of vibration-based damage detection methods is dependent upon the accuracy of modal parameters measured from structures of interest. Vibration monitoring, performed on a structure under uncertain temperature conditions, results in the uncertainty in model parameters of the structure. In this study, an experiment on the effect of various temperatures on modal characteristics of steel plate-girders is presented. First, the model plate-girder used for the experiment is described. Second, natural frequencies measured from the structure, using two different excitation sources, are described. Third, natural frequencies measured from the structure, under various temperatures, are described. Finally, the relationship between measurement temperature and natural frequency is analyzed.
A Study on the Analysis for Welding Residual Stress of Preflex Beam
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 65~71
Since the preflex beam is fabricated through welding, the pre-compressive stresses that should occur over the concrete pier are diminished by the welding residual stresses. Therefore welding residual stresses must be relieved during the fabrication. Therefore, the analysis and examination of the accurate welding residual stress distribution characteristics are necessary. In this study, accurate distribution of welding residual stress of the preflex beam is analyzed by the finite element method, using 2 dimensional and 3 dimensional elements. Further, the thermo-mechanical behavior of the preflex beam is also studied. After the finite element analysis, real distribution of welding residual stress is measured using the sectioning method, and then is compared with the simulation results. The distribution of welding residual stress by finite analysis agreed well with the experimental results.
Analysis of Stresses Induced in a Polymer Coating Layer due to Temperature Change
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 72~76
This paper deals with the stress singularity developed in a polymer layer that is coated to a concrete surface, due to temperature change. The boundary element method is employed to investigate the behavior of interface stresses. The polymeric layer is assumed to be a linear viscoelastic material, and is thermorheologically simple. The order of the singularity is obtained, numerically, for a given viscoelastic model. Numerical results exhibit the relaxation of interface stresses, and large gradients are observed in the vicinity of the free surface. Results show that the stress singularity factor is relaxed with time, while the order of the singularity increases with time for the viscoelastic model.
Measurement of Water Absorption in Anticorrosive Organic Coatings Using Quartz Crystal Microbalance (QCM)
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 77~82
The absorption of water into an anti-corrosive organic coating, such as alkyd and urethane resin coating, was investigated, using a quartz crystal microbalance (QCM). Anticorrosive properties of the coatings were also measured, by means of electrochemical impedance spectroscopy (EIS). The overall absorption of water in the coating is determined by the chemical nature of resin, and decreases with increasing thickness. The enhancement of anti-corrosive performance, through increase of coating thickness, was more remarkable in the case of the coating that hadlower equilibrium water absorption. The absorption kinetics curves were Fickian in nature. The EIS analysis confirmed that the resin, having lower equilibrium water absorption, shows higher anti-corrosive performan.
Underwater Hybrid Navigation Algorithm Based on an Inertial Sensor and a Doppler Velocity Log Using an Indirect Feedback Kalman Filter
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 83~90
This paper presents an underwater hybrid navigation system for a semi-autonomous underwater vehicle (SAUV). The navigation system consists of an inertial measurement unit (IMU), and a Doppler velocity log (DVL), accompanied by a magnetic compass. The errors of inertial measurement units increase with time, due to the bias errors of gyros and accelerometers. A navigational system model is derived, to include the scale effect and bias errors of the DVL, of which the state equation composed of the navigation states and sensor parameters is 20. The conventional extended Kalman filter was used to propagate the error covariance, update the measurement errors, and correct the state equation when the measurements are available. Simulation was performed with the 6-d.o,f equations of motion of SAUV, using a lawn-mowing survey mode. The hybrid underwater navigation system shows good tracking performance, by updating the error covariance and correcting the system's states with the measurement errors from a DVL, a magnetic compass, and a depth sensor. The error of the estimated position still slowly drifts in the horizontal plane, about 3.5m for 500 seconds, which could be eliminated with the help of additional USBL information.
A Study on the Relation between Hull Geometric Characteristics and Performance in the Yacht Design
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 91~95
Yacht design is significantly affected by the hull geometrical characteristics. Therefore, it is necessary to closely examine the relation between hull and performance, before considering characteristics of sea condition. In this study, Genetic Programming is used to derive a formula the relationship between hull geometric characteristics and performance. Using the formula, a new guideline is proposed to determine performance of a yacht.
The Northern Sea Route and Operation of Icebreaking Cargo Ships
Journal of Ocean Engineering and Technology, volume 17, issue 6, 2003, Pages 96~100
For moving cargo between the North Pacific region and Northern European ports, the Northern Sea Route, along Russia's coastline, is 35-60％ shorter than the traditionally used routes through the Suez or Panama Canals. in addition to its shorter distance, there exist extensive ports und shipping infrastructure, and the potential for developing new markets in Russia and other northern countries including Korea and Japan. These incentives attracted considerable attention from the international shipping and shipbuilding industries and have formed a cooperative international research program, called as the International Northern Sea Route Programme (INSROP) This paper is a general compilation of the historical usage, recent trade developments, the physical environment, and the practical considerations that may shape future operational mode of shipping in the NSR based on results from INSROP reports. This study focuses mainly on an operation of commercial icebreaking cargo vessels that may be utilized along the NSR.