Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Ocean Engineering and Technology
Journal Basic Information
Journal DOI :
Korean Society of Ocean Engineers
Editor in Chief :
Volume & Issues
Volume 18, Issue 6 - Dec 2004
Volume 18, Issue 5 - Oct 2004
Volume 18, Issue 4 - Aug 2004
Volume 18, Issue 3 - Jun 2004
Volume 18, Issue 2 - Apr 2004
Volume 18, Issue 1 - Feb 2004
Selecting the target year
Large-Eddy Simulation of Turbulent Channel Flow Using a Viscous Numerical Wave Tank Simulation Technique
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 1~9
As the first step to investigate the nonlinear interactions between turbulence and marine structures inside a viscous NWT, a LES technique was applied to solve the turbulent channel flow for =150. The employed turbulence models included 4 types: the Smagorinsky model, the Dynamic SGS model, the Structure Function model, and the Generalized Normal Stress model. The simulated data in time-series for the LESs were averaged in both time and space, and statistical analyses were performed. The results of the LESs were compared with those of a DNS, developed in the present study and two spectral methods by Yoon et al.(2003) and Kim et a1.(1987). Based on this research, the accuracy of LESs has been found to be still related to the number of grids for fine grid size).
Numerical Simulation of Aerodynamic Sound by the Finite Difference Lattice Boltzmann Method
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 10~17
In this research, a numerical simulation for the acoustic sounds around a two-dimensional circular cylinder in a uniform flaw was developed, using the finite difference lattice Boltzmann model. We examine the boundary condition, which is determined by the distribution function concerning density, velocity, and internal energy at the boundary node. Pressure variation, due to the emission of the acoustic waves, is very small, but we can detect this periodic variation in the region far from the cylinder. Daple-like emission of acoustic waves is seen, and these waves travel with the speed of sound, and are synchronized with the frequency of the lift on the cylinder, due to the Karman vortex street. It is also apparent that the size of the sound pressure is proportional to the central distance to the circular cylinder. The lattice BGK model for compressible fluids is shown to be a powerful tool for the simulation of gas flaws.
A Study on the Extension of Mild Slope Equation
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 18~24
In this study, the Mild slope equation is extended to both rapidly varying topography and nonlinear waves, using the Hamiltonian principle. It is shown that this equation is equivalent to the modified mild-slope equation (Kirby and Misra, 1998) for small amplitude wave, and it is the same form with the nonlinear mild-slope equation (Isobe, 1994) for slowly varying bottom topography. Comparing its numerical solutions with the results of some hydraulic experiments, there is good agreement between them.
Disaster Characteristics Analysis at Busan Coastal Areas by Typhoon Maemi in 2003
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 25~32
We surveyed the coastal structure damage created by typhoon ‘Maemi’, which heavily struck the Korean peninsula on September 12, 2003. The survey revealed that high tides and strong winds induced by the typhoon were the main causes of the coastal damage, especially in the Busan areas. Though some experimental real-time coastal monitoring stations captured the typhoon movements at the critical time, more systematic and complete system should be implemented to save human lives and property from huge typhoon disasters.
An On-Line Adaptive Control of Underwater Vehicles Using Neural Network
Kim, Myung-Hyun ; Kang, Sung-Won ; Lee, Jae-Myung ;
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 33~38
All adaptive neural network controller has been developed for a model of an underwater vehicle. This controller combines a radial basis neural network and sliding mode control techniques. No prior off-line training phase is required, and this scheme exploits the advantages of both neural network control and sliding mode control. An on-line stable adaptive law is derived using Lyapunov theory. The number of neurons and the width of Gaussian function should be chosen carefully. Performance of the controller is demonstrated through computer simulation.
An Experimental Study on the System Identification and Anti-Rolling System Design for a Ship with Flaps
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 39~45
We have investigated the usefulness of an active stabilizing system to reduce ship rolling under disturbances, using varying reaction of the flaps. In the proposed anti-rolling system for a ship, the flaps, as the actuator, are installed on the stern, in order to reject the rolling motion induced by disturbances, such as waves. The action induced by the flaps, which is dependent upon the power of the disturbances, can keep the ship in balance. In this study, we define the system parameters under the given system structure, using spectral analysis and experimental studies. Based on this information, we design the controller to evaluate the usefulness of the proposed system.
Natural Frequencies of Beams with Step Change in Cross-Section
Kim, Yong-Cheul ; Nam, Alexander-V. ;
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 46~51
Natural frequencies of the transverse vibration of beams with step change in cross-section are obtained by using the asymptotic closed form solution. This closed form solution is found by using WKB method under the assumption of slowly varying properties, such as mass, cross-section, tension etc., along the beam length. However, this solution is found to be still very accurate even in the case of large variation in cross-section and tension. Therefore, this result can be easily applied to many engineering problems.
A Study on the Numerical Analysis of Welding Heat Distribution of Preflex Beam
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 52~57
Preflex beam is a method of construction designed to hold the pre-compressive stresses over the concrete pier by the preflexion load. During the fabrication of the girder, welding causes residual stresses. The welding residual stresses must be relieved in order to generate the accurate compressive pre-stresses. In this study, to determine the thermal distribution characteristics on the girder by welding, both three-dimensional finite element analysis and two-dimensional finite element analysis, in a quasi-steady state, is carried out. After comparing each result between the three-dimensional analysis and the two-dimensional analysis, finite element analysis is carried out against the actual girder, and the welding thermal distribution characteristic over the preflex beam is analyzed. It is possible to provide the input data for the analysis of the welding residual stresses.
Evaluation on Creep Properties of Reduced Activation Ferritic Steel(RAFs) for Nuclear Fusion Reactor
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 58~63
Reduced Activation Ferritic/Martensitic Steels (RAFs) are leading candidntes for structural materials of a D-T fusion reactor. One of the RAFs, JLF-l (9Cr-2W-V, Ta) has been developed and has shown to have good resistance against high-fluency neutrino irradiation and good phase stability. Recently, in order to clarify the strengthening mechanisms at high temperatures, a new scheme to improve high temperature mechanical properties is desired. Therefore, the test technique development of high temperature creep behaviors for this material is very important. In this paper, the creep properties and creep life prediction, using the Larson-Miler parameter method for JLF-l to be used for fusion reactor materials or other high temperature components, are presented at the elevated temperatures of 50
. It was confirmed, experimentally and quantitatively, that a creep life predictive equation, at such various high temperatures, is well derived mr the LMP method.
Probability Distribution Characteristics for Elevated Temperature Mechanical Properties of Stainless Steels
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 64~69
The characteristics of the probability distribution for mechanical properties, e.g. tensile strength, reduction of area, and elongation, for STS304 stainless steel in elevated temperature are investigated. Tensile test is performed by constant crosshead speed controls with 1mm/min. The probability distribution function of measured mechanical properties seems to follow
3-parameter Weibull, and shows a slight dependence on the temperature. When the temperature is raised, the shape parameter a is increased, but both the scale parameter
and location parameter v are decreased.
Effects of Nb, V on the Mechanical Properties of Continuous Casting Rolls Overlaidhang
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 70~76
In the steel marking industry, most companies have adapted the continuous casting process, due to its economical benefit. Casting rolls are utilized for frictional drive and the transport of solidifying slap. Dimensional tolerances, mechanical stability, and surface condition of the casting rolls can affect both the surface and the internal quality of the product being cast. To overcome these problems, the industry now is focused on accelerating the rate of technological improvements. This study has been undertaken for the development of casting rolls overlaid materials (SAW FCW wire), with the addition of Vanadium and Molybdenum to the martensitic stainless steel, in order to increase tensile strength and hardness at elevated temperatures.
A Study on the Irregular Nesting Problem Using Genetic Algorithm and No Fit Polygon Methodology
Journal of Ocean Engineering and Technology, volume 18, issue 2, 2004, Pages 77~82
The purpose of this study is to develop a nesting algorithm, using a genetic algorithm to optimize nesting order, and modified No Fit Polygon(NFP) methodology to place parts with the order generated from the previous genetic algorithm. Various genetic algorithm techniques, which have thus far been applied to the Travelling Salesman Problem, were tested. The partially mapped crossover method, the inversion method for mutation, the elitist strategy, and the linear scaling method of fitness value were selected to optimize the nesting order. A modified NFP methodology, with improved searching capability for non-convex polygon, was applied repeatedly to the placement of parts according to the order generated from previous genetic algorithm. Modified NFP, combined with the genetic algorithms that have been proven in TSP, were applied to the nesting problem. For two example cases, the combined nesting algorithm, proposed in this study, shows better results than that from previous studies.