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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
Journal Basic Information
Journal DOI :
Korean Society of Ocean Engineers
Editor in Chief :
Volume & Issues
Volume 11, Issue 4 - Nov 1997
Volume 11, Issue 3 - Aug 1997
Volume 11, Issue 2 - May 1997
Volume 11, Issue 1 - Feb 1997
Selecting the target year
A Fundamental Study on the Welding Deformation of Plate by Using F.E.M.
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 1~6
When structures are constructed by welding, heat conduction brings welding deformation. This is accompanied by complicated mechanical phenomenon such as material nonlinear and geometric nonlinear behavior. Hitherto, the research of welding deformation has been accomplished by an analytical method and experimental data in Korea. In this paper, the computer program by F.E.M.(finite element method) which could analyze the deformation of thin plate considering phenomena(both material and geometric nonlinear behavior) has been developed and verified. The production mechanism and characteristics in the welding deformation of plate are studied by the results.
Total Lagrangian Finite Element Analysis of Lateral Buckling for Thin Beam Structures
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 7~22
A finite element analysis is performed for lateral buckling problems on the basis of a geometrically nonlinear formulation for a beam with small elastic strain but with possibly large rotations. The total Lagrangian formulation for a general large deformation, which involves finite rotations, is chosen and the exponential map is used to treat finite rotations from the Eulerian point of view. For lateral buckling, the point of vanishing determinant of the resulting unsymmetric tangent stiffness is traced to examine its relationship to bifurcation points. It is found that the points of vanishing determinant is not corresponding to bifurcation points for large deformations in general, which suggests that the present unsymmetric tangent stiffness is not an exact first derivative of internal forces with respect to displacement. This is illustrated through several numerical examples and followed by appropriate discussion.
Effect of Water Environment on the Mechanical Properties of Unidirectional CFRP
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 23~30
The purpose of this paper is to investigate the water environmental effect on the mechanical properties of carbon fiber/epoxy composites. Moisture concentration absorbed in CFRP under various water environment was calculated and degradation of mechanical properties for each wet composite laminates is investigated by performing the flexual and tensile test. The results show that moisture absorption is accelerated in higher temperature environment and under the same temperature sea water environment prompts more absorption than fresh water. As increasing the water temperature and moisture concentration tensile and flexual strength decreased as much as 25%-40% compared with dry condition.
Effect of Sunshine Treatment on Strength in Al 6061/AFRP Hybrid Composite
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 31~39
This research is to evaluate the effect of sunshine treatment on the strength in the Al 6061/AFRP hybrid composite(APAL). APAL specimens were processed by autoclave curing system under the constant condition of curing temperature, time and aluminum surface pertreatment. Aramid patched aluminum alloy can be widely used for the repair of the damage part of the aircraft. The tensile strength of the sunshine treated APAL 2P and 6P composite is 14%, 22% smaller than that of the non-treated material. The interlaminar shear strength of the APAL specimens for the adhesive length of 5mm is 24% higher than that of the APAL for the adhesive length of 10mm. In the case of APAL DS 1P material, interlaminar shear strength of the specimen which was sunshine treated for 200 hours is 21% smaller than that of the non-treated material while interlaminar shear strength of the specimen which was immersed in a 70.deg. C fresh water for 1200 hours decreases by 75.7%.
High Temperature Creep Life Prediction of Friction Welded Joints by Initial Strain Method and the AE Evaluation
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 40~48
There are many research results as individual uni-axial tension creep test of heat-resisting materials. However, there are very few about the study on the high temperature creep test for the Initial Strain Method, and especially any study on it about the friction welded joints of SUH3 to SUH35. One of the important concerns is a reliable method of evaluating static creep properties. No reliable method seems available at present to evaluate or predict static creep properties. So, the reliable method to evaluate and predict them by the ISM and AE techniques was made.
Fatigue Strength Characteristics of 1Cr-1Mo-0.25V Steel by Improved TiN Coated Processes
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 49~60
This paper deals with the effect of coating layer on the fatigue strength of TiN coated 1Cr-1Mo-0.25V steel prepared by using the arc ion plating (AIP) process, in which it was characterized by the presence of extractor grid (ion filter). The rotary bending fatigue tests were carried out under room air conditions, and the fatigue crack initiation and growth bwhavior were observed by using plastic replica method. As experimental results, it was found that the obvious improvement of fatigue life at lower stress region was confirmed in TiN coated specimen processed with ion filter. It was also exlained that the increase of fatigue life in the case of an improved AIP process with ion filter was attributed to the retardation of crack initiation of the substrate surface due to hard coating layer, more densly formed with the reduced size and density of droplets.
A Program Development of Life Prediction Simulation for Multi-Surface Cracks on the Finite Plate
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 61~75
The social demand urges us to use some equipments and structures in high temperature environment. By this occasion, the necessity of studying the fatigue crack growth is an important aspect of new materials. However, the present situation is rarely to accumulate the fatigue data. Especially, 1Cr-1Mo-0.25V steel and 304 stainless steel have been increased to be used under the severe condition of high temperature. And so, the fatigue estimation of those materials is important and appropriate. Fatigue tests have been carried out to examine the crack initiation, growth behaviour for the small fatigue crack of 1Cr-1Mo-0.25V steel and 304 stainless steel at room temperature and 538
. The remote measurement system which has many merits of checking and saving the image for detailed examination was applied to closely detect the crack length. Generally, the fatigue crack initiated in the form of multiple cracks and grew each other. And then it coalesced to become a major crack. The major crack governed the rest of the fatigue life. In the growing process, each peripheral cracks interact and grow for a certain period. After then, it coalesced and fractured. On the basis of the above experimental data for the small crack, a simulation program was developed to predict the residual life time and to estimate the integrity of machine elements and structures. At the same time, the simulation was extended to 1Cr-1Mo-0.25V steel. The simulation results have shown a good agreement to those of the experimental ones for both materials of 1Cr-1Mo-0.25V steel and 304 stainless steel with small cracks. The NASCRAC has applied to compare the fatigue life with the experimental results. And so, it can be said that the simulation program is valuable tools to the industrial fields.
Wave Exciting Forces on Multiple Floating Bodies of Semisubmersible Type in Multi-directional Irregular Waves
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 76~89
The hydrodynamic interaction characteristics between multiple floating bodies of semisubmersible type are examined to present the basic data for the design of huge offshore structures supported by a large number of the floating bodies in multi-directional irregular waves. The numerical approach is based on a combination of a three-dimensional source distribution method, the wave interaction theory and the spectral analysis method. The effects of wave directionality on the wave exciting forces acting on multiple floating bodies in multi-directional irregular waves also have been pointed out.
An Implicit Unstructured Finite Element Method for Diffraction of Water Waves by Two-Dimensional Floating Breakwaters
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 90~101
A hybrid element method is presented for two-dimensional diffraction problem of water waves. In this method, only a limited fluid domain close to irregular bodies is discretized into conventional finite elements, while the remaining infinite domain is treated as one element with analytical representations of high accuracy. A finite element grid is automatically generated by using Dealunay triangulation based on the Bowyer's algorithm and a linear system of equations is approximately solved with the ILU-CGS algorithm. To validate the present scheme, Computational results are compared with the existing experimental data and other numerical solutions.
A Numerical Analysis of an Unsteady Flow in a Cavity Using an Ekman Pumping Model
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 102~110
A two dimensional shallow-water flow around a cavity driven by a sinusoidally oscillating external flow was studied numerically with an Ekman pumping model. A container model of "T" shape was constructed in the numerical computation for comparison with the experimental observation. The material transport in the external region is in good agreement with the experimentally recorded particle trajectories. It turns out that two large coherent vortices situated in the exterior region of the cavity are responsible for clockwise and counterclockwise drift motions, in large scale, of particles. The Ekman pumping model suggested in this study was found to be satisfactory.isfactory.
Response of the Wave Spectrum to Turning Winds
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 111~121
The spectral energy balance model is composed and the nonlinear interaction is approximated by the discrete interaction parameterization as in WAM model. The numerical results of durational limited growth test agree very well with those of the exact model, EXACT-NL. The response of a wave spectrum to a change in wind direction is investigated numerically for a sequence of direction changes 30
. The high frequency components relax more repidly to the new wind direction than the low frequency components and the relaxation process also depends on the wave age. For wind direction changes less than 60
, the coupling by nonlinear interaction is so strong that the secondary peak in input source distribution is counteracted by the negative lobe of the nonlinear interaction. For wind direction changes grater than 60
, a second independent wind-sea spectrum is generated in the new wind direction, while the old spectrum gradually decays as swell.
A Study on Critical Reynolds Numbers of Two-Dimensional Closed Cavity by CFD
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 122~129
Flow characteristics of two-dimensional closed square cavities near unsteady critical Reynolds numbers were studied numerically at five Reynolds numbers : 8
were investigated. A convection conservative difference scheme based upon SOLA to maintain the nearly 2nd-order spatial accuracy was adopted on irregular grid formation. Irregular grid number is 80
80 and its minimum size is about 1/400 of the cavity height(H) and its maximum is about 1/53 H. The result shows that the critical Reynolds number indicating the emergence of flow unsteadiness exists near Re=8.5
and their flow patterns reveal periodic fluctuation during transient and fully-developed stages.
Experimental and Computational Investigation of the Flow around a Circular Cylinder
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 130~140
Flow-Guider Applied to Controlling Current in a Bay
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 141~151
This paper deals with a numerical study of flow-guider applied to controlling current in a bay. Two dimensional numerical model for tidal currents based on the depth averaged equation is developed and standard k-.epsilon. model is adopted to determine the turbulence diffusion. Equations are described in a generalized coordinate system to be implemented by non-staggered grid system and discretized by using finite volume method. Unsteady flow is simulated by fully implicit scheme. Hybrid scheme and central differencing are used to compute the convective terms and source terms, respectively. The tidal current in a rectangular bay is simulated and it gives satisfactory results. The realistic and distinct models of a large structure placed in bay are also exemplified with or without flow-guiders. The simulation results show that the flow-guider gives the residual tidal current in the bay by the different flux with respect to the direction of tidal current.
Analysis of Pressure Fluctuations in Oil Hydraulic Pipe Network
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 152~158
An analyzing method for pressure fluctuations in oil hydraulic pipe network was developed in this study. The object pipe network has multi-branch configuration, and the pipelines of it are composed of steel tubes, flexible hoses. Also, accumulators, orifices and lumped oil volume components are attached on it. Transfer matrix method, in other words impedance method, was used for the analysis. The reliability and usefulness of the analyzing method were confirmed by investigation computed results and experimental results got in this study.
A Study on Unsteady Temperature Distribution Analysis of Moss Type LNG Carrier by Insulation System
Kim, Jin-Goo ; Kim, Yong-Mo ; Kim, Chun-Sik ;
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 159~168
Depth Control of an Autonomous Underwater Vehicle with System Uncertainties Based on Discrete Variable Structure System
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 169~179
This paper presents a discrete-time sliding mode control of an autonomous underwater vehicle with parameter uncertainties and long sample interval based on discrete variable structure system. Although conventional sliding mode montrol techniques are robust to system uncertainties, in the case of the system with long sample interval, the sliding control system reveals chattering phenomenon and even makes the system unstable. This paper considers the AUV which acquires position informations from a surface ship through an acoustic telemetry system with a certain discrete interval. The control system is designed on the basis of a Lyapunov function and a sufficient condition of the switching gain to make the system stable is give. Each component of the switching gain can be determined separately one another. The controller is robust to the uncertainties, and reaching condition of the control system is satisfied for any initial condition. This control law is a generalized form of the discrete sliding mode control and reduce the chattering problem considerably. Motion control of the AUV in the vertical plane shows the effectiveness of the proposed technique.
Design and implementation of the MAC protocol for underwater vehicle network
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 180~188
This paper proposes a new efficient MAC(Media Access Control) protocol to establish the ultrasonic communication network for underwater vehicles, which ensures a certain level of maximum throughput regardless of the propagation delay of ultrasonic and allows fast data transmission through the multiple ultrasonic communication channel. A MAC protocol for underwater communication network that allows 'peer-to-peer' communication between a surface ship and multiple underwater systems is designed, and the proposed control protocol is implemented for its verification.
An oil spill tracking buoy using GPS
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 189~196
An oil tracking system that monitors the spilt oil trajectory by using GPS was developed. The system consists of a tracking buoy deployed on the oil spilt area and an onshore(or onboard) monitoring station. The tracking buoy is equipped with GPS, signal converter, handy radio and battery while the monitoring station includes a station radio, signal converter, antennas and PC. The hull shape of buoy is designed to effectively simulate the spilt oil movement at sea surface. Radio sets for HAM are used as a data transmitter and a data receiving station, and signal converter is also for amateur use. A field experiment was conducted and it was shown that the integrated system is relable and robust. The developed oil tracking system reveals reatively good performance at reasonable cost. In favorable environment the system may communicate in the distance more than 50km.
An Identification Method of Secondary Resistance for Quick Torque Control in Induction Motors
Jeong, Seok-Kwon ;
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 197~204
A study on the conceptual design of oceanographic buoy systems
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 205~212
The major subject of this paper is the conceptual design of a cable-buoy system based on mechanics of floating bodies and mooring lines. The goal is to present a systematic relevant analysis procedure for the conceptual design of oceanographic buoy systems. The dynamics of a free floating body with an anchoring line is studied and a model is proposed through the primary engineering.
A study on a design for a centrifugal pump impeller shape
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 213~220
In this study, a design for a shape of centrifugal pump impeller has been performed using a p.c. under a Windows environment. Interaction between a user and a computer has been easily established using the Visual Basic. In determining an outer diameter of an impeller, steps are divided into two, a basic computational step and a refinment step. In this way user can enter his/her experience at the refinment step and hence can expect to lessen the nonlinear nature inherent to the design. In determining a shape of a side view of an impeller, the Bezier cubic curve has been used, and it can be seen that the Bezier cubic curves are well suited in the shape design under a Windows environment. By simply manipulating the four control points, one can generate various cubic curves among which one is selected. Also, a simple method, which can determine the curved position of an impeller vane, has been developed. These data can be used for final CAD drawings.
A study on the hull form development of the G/T 340ton class high speed fishery patrol ship
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 221~226
This study was carried out for the hull form development of G/T 340ton class high speed fishery patrol ship by Chosun University at the Circulating Water Channel cooperatively with Korea Maritime Service. Same size of 15knots class fishery patrol ship was selected as a parent form (Model number : CU-015), and modified fore and after body to be suitable for the operation at 20 knots. To minimize the breaking wave in the vicinity of fore body at high speed zone, high bulb nose and slender fore body hull form was chosen as an initial condition. Meanwhile, to ensure the engine room space keeping high resistance-propulsion performance, U-type stern hull form was developed.
An optimum design of a ship based on numeric and knowledge processing
Kim, Soo-Young ;
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 227~238
A study on the nesting S/W development of piece with PC-CADRA
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 239~248
The nesting of parts cut on raw steel plate has been a subject of interest to the shipbuilding industry for many years. "Nesting" is defined operation of layout of the parts on the raw material with minimizing the waste rate. Therefore, it is very important to optimize the cutting area. Since the existing nesting programs are prepared for expensive workstations and the expert, it is needed to develop nesting program for personal computer to improve the technology of small/middle sized shipyards and their productivity. This study involves development and application of appropriate optimization technique to solve the problem of plate nesting. And the appropriate D/B for storing nesting data developed, the function of D/B is introduced in this paper.his paper.
A Study for Rationalization of Lifting Lug Design of Ship Block
Journal of Ocean Engineering and Technology, volume 11, issue 4, 1997, Pages 249~261
A basic study on the lifting lug design has performed through the rational and systematic process. In order to evaluate the proper design-load distribution around lug eye investigation of contact force between lifting lug and shackle pin is performed using non-linear parametric analysis idealized by gap element models. Gap element modeling and nonlinear analysis procedures are illustrated and discussed based on MSC/NASTRAN. Some analysis and design guides are suggested through the consideration of several important effects such as stress distribution pattern, circumferential contact force distribution along the lug eye face, loading share rate between lug main plate and doubler, effect of loading direction, relation between applied force and deflection and size effect of shackle pin radius. Additionally optimum design studies are performed and general trends according to the variation of design parameters are suggested.