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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 19, Issue 6 - Dec 2005
Volume 19, Issue 5 - Oct 2005
Volume 19, Issue 4 - Aug 2005
Volume 19, Issue 3 - Jun 2005
Volume 19, Issue 2 - Apr 2005
Volume 19, Issue 1 - Feb 2005
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Submerged Horizontal and Vertical Membrane Wave Barrier
Kee S.T. ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 1~11
In the present paper, the hydrodynamic properties of a Rahmen type flexible porous breakwater with dual fixed pontoon system interacting with obliquely or normally incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes hinged at the side edges of dual fixed pontoons, and a submerged horizontal membrane that both ends are hinged at the steel frames mounted pontoons. The dual vertical membranes are extended downward and hinged at bottom steal frame fixed into seabed. The wave blocking and dissipation mechanism and its effects of permeability, Rahmen type membrane and pontoon geometry, pretensions on membranes, relative dimensionless wave number, and incident wave headings are thoroughly examined.
Hindcasting of Storm Surge at Southeast Coast by Typhoon Maemi
KAWAI HIROYASU ; KIM DO-SAM ; KANG YOON-KOO ; TOMITA TAKASHI ; HIRAISHI TETSUYA ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 12~18
Typhoon Maemi landed on the southeast coast of Korea and caused a severe storm surge in Jinhae Bay and Masan Bay. The tide gage in Masan Port recorded the storm surge of a maximum of more than 2m and the area of more than 700m from the Seo Hang Wharf was flooded by the storm surge. They had not met such an extremely severe storm surge since the opening of the port. Then storm surge was hindcasted with a numerical model. The typhoon pressure was approximated by Myers' empirical model and super gradient wind around the typhoon eye wall was considered in the wind estimation. The land topography surrounding Jinhae Bay and Masan Bay is so complex that the computed wind field was modified with the 3D-MASCON model. The motion of seawater due to the atmospheric forces was simulated using a one-layer model based on non-linear long wave approximation. The Janssen's wave age dependent drag coefficient on the sea surface was calculated in the wave prediction model WAM cycle 4 and the coefficient was inputted to the storm surge model. The result shows that the storm surge hindcasted by the numerical model was in good agreement with the observed one.
Responses of Submerged Double Hull Pontoon/Membrane Breakwater
Kee S.T. ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 19~28
The present paper outlines the numerical investigation of the incident wave interactions with fully submerged and floating dual double hull pontoon/vertical porous membrane breakwaters. Two dimensional five fluid-domains hydro-elastic formulation was carried out in the context of linear wave body interaction theory to study the wave interaction with the double hull of pontoon-membranes. The submerged circular pontoon is consisted of double hulls, which is filled with water in the void space between the outer structure and inner solid buoyant structure. Hydrodynamic characteristics of the proposed system with dual floating double-hull-pontoons filled with water have been studied numerically for the various incident waves. This study is a beginning stage research for the dual double hull porous pontoons/vertical porous membranes breakwaters which is ideally designed in order to suppress significantly the transmitted and reflected waves simultaneously.
Shoaling and Breaking Characteristics of Fully Nonlinear Boussinesq Model
YOON JONG-TAE ; PARK SEUNG-MIN ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 29~33
The accuracy of predicting wave transformation in the nearshore is very important to wave hydrodynamics, sediment transport, and design of coastal structures. Numerical experiments are conducted to identify the shoaling and breaking characteristics of a fully nonlinear Boussinesq equation-based model. Simulated shoaling showed good agreement with the Shouto's formula, and the results of the breaking experiment agreed well with experimented data, over several beach profile.
Experimental Study of the Wave Overtopping/Reflection Rate on the Shapes of Rubble Mound Structures
SOHN BYUNG-KYU ; KIM HONG-JIN ; AN HEUI-CHUN ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 34~39
All of the design criterion are not only formulated by an internal study, concerning the design of maritime structures, but also by the guarantee that internal design technology is essential, at least according to theoretical and experimental studies. Furthermore, the basic data, which is necessary for the development of a more stable design of breakwater structures, should be ensured, according to current research and analysis of damage created by water waves. According to the necessity to solve the problems that occur in the design and construction of ocean structures, until now, it is recognized that the hydraulic experiments are important. This paper provides the design of structures to decrease the energy created by waves. Suggestions to make contributions to the development of ocean/fisheries technology are also discussed. It is better to use S-type coastal structures/breakwaters than to use uniform type breakwaters, concerning stability, reflection, and overtopping.
Design Optimization of a Deep-sea Pressure Vessel by Reliability Analysis
JOUNG TAE-HWAN ; NHO IN-SIK ; LEE JAE-HWAN ; HAN SEUNG-HO ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 40~46
In order to consider the statistical properties of probability variables which are used in structural analysis, the conventional approach of using safety factors based on past experience, are usually used to estimate the safety of a structure. The real structures could only be analyzed with the error in estimation of loads, materials and dimensional characteristics. Errors should be considered systematically in the structural analysis. In this paper, we estimated the probability of failure of two pressure vessels, simultaneously, using computational analysis. One pressure vessel, theoretically, had no stiffener whereas the other had. This paper also discusses sensitivity values of random variables in the rounded parts of the pressure vessel which had ring-style stiffener in the center of the external area which had ring-style stiffener. Finally, we show that the reliability index, and the probability of failure, can be calculated to particular tolerance limits.
Free Spanning of Offshore Pipelines by DNV
CHOI HAN SUK ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 47~52
This paper introduces a procedure for free span and fatigue analysis of offshore pipelines per DNV-RP-F105, 2002. The new method includes the axial force and deflection load in pipelines. The screening criteria were established to calculate the allowable span lengths in the new design codes. The screening criteria allows a certain amount of vortex-induced vibration due to wave and current loading. However, the induced pipe stresses are very small and usually below the limit stresess of typical S-N curves. In contrast, the conventional criteria did not allow any vortex-induced vibration in the free span of pipelines. Thus, the screening criteria yields reduced allowable span lengths. A simplified procedure was established to calculate the fatigue damage due to long-term current distribution. The long-term current statistics was assumed with a 3-parameter Weibull distribution. The fatigue damage was estimated for the span lengths obtained from the screening criteria for various conditions. Sample calculations show the effect of axial force for various boundary conditions. Comparisons with conventional criteria are included.
The Effects of pH on the Corrosion Characteristics in Dissimilar Friction Welded Zone of IN713LC-SCM440
JO SANG-KEUN ; KONG YU-SIK ; KIM YOUNG-DAE ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 53~59
The effect of pH on the corrosion characteristics in the dissimilar friction welded zone of IN713LC-SCM440 in the loaded torsional stress was studied. The corrosion experiment was performed for 120 hours on the specimens with five steps of pH. The surface corrosion pattern of the SCM440 area showed global corrosion and narrow pitting, which was caused by galvanic corrosion between friction welded IN713LC and SCM440, but corrosion did not proceeded from the IN713LC area. The average relative electrode potential gradually tends to decrease with the elapse of the immersion time in the acidity area. The average corrosion current also gradually tend to decrease The corrosion rate showed a larger value when the average relative electrode potential was higher and the average relative current was lower. The corrosion rate showed a larger value when the average relative electrode potential was higher in the acidity area, and it showed large when the average relative electrode potential was lower in the alkalinity area.
The Effect of Fleet-Angle on Sway Motions of a Cargo: Compatibility and Bifurcation Conditions
SHIN JANG-RYONG ; GOH SUNG-HEE ; HONG KYUNG-TAE ; HONG KEUM-SHIK ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 60~66
This paper investigates the relationship between the fleet-angle of the hoisting rope and the swaying and pitching angles of a cargo in container cranes. It is found that for a given disturbance, when the fleet-angle is large, the sway Angle becomes smaller, but the pitching angle becomes larger. Therefore, for a quick suppression of a sway motion, it is desirable to have a large fleet-angle. The compatibility and bifurcation conditions, regarding instability, are characterized.
Speed, Depth and Steering Control of Underwater Vehicles with Four Stem Thrusters - Simulation and Experimental Results
JUN BONG-HUAN ; LEE PAN-MOOK ; LI JI-HONG ; HONG SEOK-WON ; LEE JIHONG ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 67~73
This paper describes depth, heading and speed control of an underwater vehicle that has four stern thrusters of which forces are coupled in the diving and, steering motion, as well as the speed of the vehicle. The optimal linear quadratic controller is designed based on a linearized- state space model, developed by combining the dynamic equations of speed, steering and diving motion. The designed controller gives provides an optimal thrust distribution, minimizing the given performance index to control speed, depth and heading simultaneously. To validate the performance of the controller, a simulation and tank-test are carried out with DUSAUV (Dual Use Semi-Autonomous Underwater Vehicle), developed by KORDI as a test-bed for testing new underwater technologies. Optimal gains of the controller are tuned, using a computer simulation environment with a nonlinear 6-DOF numerical DUSAUV model, developed by PMM (Planner Motion Mechanism) test. To verify the performance of the presented controller in experiment, a tank-test with DUSAUV is carried out in the ocean engineering basin in KORDI. The experimental results are also compared with the simulation results to investigate the accordance of the numerical and the real mode
A Study on a 3-D Localization of a AUV Based on a Mother Ship
LIM JONG-HWAN ; KANG CHUL-UNC ; KIM SUNG-KYUN ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 74~81
A 3-D localization method of an autonomous underwater vehicle (AUV) has been developed, which can solve the limitations oj the conventional localization, such as LBL or SBL that reduces the flexibility and availability of the AUV. The system is composed of a mother ship (small unmanned marine prober) on the surface of the water and an unmanned underwater vehicle in the water. The mother ship is equipped with a digital compass and a GPS for position information, and an extended Kalman filter is used for position estimation. For the localization of the AUV, we used only non-inertial sensors, such as a digital compass, a pressure sensor, a clinometer, and ultrasonic sensors. From the orientation and velocity information, a priori position of the AUV is estimated by applying the dead reckoning method. Based on the extended Kalman filter algorithm, a posteriori position of the AUV is, then, updated by using the distance between the AUV and a mother ship on the surface of the water, together with the depth information from the pressure sensor.
Development of an Extended Kalman Filter Algorithm for the Localization of Underwater Mining Vehicles
WON MOON-CHEOL ; CHA HYUK-SANG ; HONG SUP ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 82~89
This study deals with the development of the extended Kalman filter(EKF) algorithm for the localization of underwater mining vehicles. Both simulation and experimental studies in a test bed are carried out. For the experiments, a scale dawn tracked vehicle is run in a soil bin containing cohesive soil of bentonite-water mixture. To develop the EKF algorithm, we use a kinematic model including the inner/outer track slips and the slip angle for the vehicle. The measurements include the inner and outer wheel speeds from encoders, the heading angle from a compass sensor and a fiber optic rate gyro, and x and y coordinate position values from a vision system. The vision sensor replaces the LBL(Long Base Line) sonar system used in the real underwater positioning situations. Artificial noise signals mimicking the real LBL noise signal are added to the vision sensor information. To know the mean slip values of the tracks in both straight and cornering maneuver, several trial running experiments are executed before applying the EKF algorithm. Experimental results show the effectiveness of the EKF algorithm in rejecting the sensor measurements noise. Also, the simulation and experimental results show close correlations.
A Research on the Approximate Formulae for the Speed Loss at Sea
KWON YOUNG-JOONG ; KIM DAI YOUNG ;
Journal of Ocean Engineering and Technology, volume 19, issue 2, 2005, Pages 90~93
An improved approximate formula is presented for Series 60 forms, modifying the approximate formula, developed by the Author in 1983. The weather formula is based on interpretations of detailed calculations of speed loss, due to wind(van Berlekom), motions(Maruo), and wave reflection resistance(Kwon). Comparison is made between the result of the approximate formula and the one of detailed calculation. The result of the formula is also compared with some published full-scale data for speed loss.