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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 22, Issue 6 - Dec 2008
Volume 22, Issue 5 - Oct 2008
Volume 22, Issue 4 - Aug 2008
Volume 22, Issue 3 - Jun 2008
Volume 22, Issue 2 - Apr 2008
Volume 22, Issue 1 - Feb 2008
Selecting the target year
Tikhonov's Solution of Unstable Axisymmetric Initial Value Problem of Wave Propagation: Deteriorated Noisy Measurement Data
Jang, Taek-Soo ; Han, So-Lyoung ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 1~7
The primary aim of the paper is to solve an unstable axisymmetric initial value problem of wave propagation when given initial data that is deteriorated by noise such as measurement error. To overcome the instability of the problem, Tikhonov's regularization, known as a non-iterative numerical regularization method, is introduced to solve the problem. The L-curvecriterion is introduced to find the optimal regularization parameter for the solution. It is confirmed that fairly stable solutions are realized and that they are accurate when compared to the exact solution.
Influence of Ultrasonic Waves on the Stacking Orientation in Carbon Fiber/Epoxy Composite Laminates
Park, Je-Woong ; Kim, Do-Jung ; Hsu, David K. ; Seo, Young-Hwan ; Im, Kwang-Hee ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 8~13
In this study, an investigation of shear wave ultrasonic technique was carried out to detect stacking orientation error for CF/Epoxy quasi-isotropy composite laminates. The ultrasonic shear wave is particularly sensitive to ply orientation and layup sequence in tire CF/Epoxy composite laminates. In the manufacturing of composite laminates, it is important that layup errors be detected in samples. In this work, an effect was mack to develop shear wave techniques that can be applied to composite laminates. During testing, the mast significant problem is that the couplant conditions do not remain the same because of its changing viscosity. The design and use of a shear ware transducer would greatly alleviate the couplant problem. A pyramid of aluminum, with isosceles triangle (two 45o angles) sides, was made to generate shear waves, using two longitudinal transducers based on an ultrasonic-polarized mechanism. A signal splitter was connected to the pulser jack on a pulser/receiver and to the longitudinal transducers. The longitudinal transducers were mounted with mineral oil, and the shear transducer was mounted with burnt honey on the bottom as a receiver. The shear wave was generated at a maximum and a minimum based on the ultrasonic-polarized mechanism. Results show it is feasible to measure layup error using shear wave transducers on a stacking of prepregs in composites.
Application to Speed Control of Brushless DC Motor Using Mixed
PID Controller with Genetic Algorithm
Duy, Vo Hoang ; Hung, Nguyen ; Jeong, Sang-Kwun ; Kim, Hak-Kyeong ; Kim, Sang-Bong ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 14~19
This paper proposes a mixed
optimal PID controller with a genetic algorithm based on the dynamic model of a brushless direct current (BLDC) motor and applies it to speed control. In the dynamic model of the BLDC motor with perturbation, the proposed controller guarantees arobust and optimal tracking performance to the desired speed of the BLDC motor. A genetic algorithm was used to obtain parameters for the PID controller that satisfy the mixed
constraint. To implement the proposed controller, a control system based on PIC18F4431 was developed. Numerical and experimental results are shown to prove that the performance of the proposed controller was better than that of the optimal PID controller.
An Analysis of the Variation in the Settling Properties of Cohesive Sediments before and after Closure of the Saemankeum Seadike
Yang, Su-Hyun ; Hwang, Kyu-Nam ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 20~26
The primary purpose of this study was to quantitatively examine whether there was a difference in the settling velocities of cohesive sediments in the Saemankeum artificial lake before and after the closure of the Saemankeum seadike. Through in situ sediment sampling and laboratory experiments, the settling velocities were estimated as a function of the suspension concentration and their physico-chemical properties, such as grain size distribution, the percentage of organic contents, mineralogical composition, etc. were also examined. In this study, their inter-relation with settling velocities were also analyzed qualitatively. The result of the settling tests for Saemankeum sediments showed that there was a big difference in the settling velocities before and after the closure of the Saemankeum seadike. Its settling velocities in a flocculated settling region became remarkably larger after the closure compared to those before the closure, while they were similar but relatively smaller in a hindered settling region. This was found to be mainly due to the difference in their grain size.
Effects of Wave Dissipation with Circular Cylinders
Lee, Seong-Dae ; Kim, Seong-Deuk ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 27~33
One of the central problems in astudy of the coastal surface wave environment is predicting the transformation of waves as they propagate toward the shore. The transformation is mainly due to the existence of obstacles, such as breakwaters and vertical cylinders. In general, the types of wave transformation can be classified as follows: wave diffraction, reflection, transmission, scattering, radiation, et al. This research dealtwith wave transmission and dissipation problems for two dimensional irregular waves and vertical circular cylinders. Using the unsteady mild slope equation, a numerical model was developed to calculate the reflection and transmission of regular waves from a multiple-row circular breakwater and vertical cylinders. In addition, hydraulic model experiments were conducted with different values for the properties between tire piles and the opening ratio (distances) between the rows of the breakwater. It was found that the transmission coefficients decreased with a decrease in the opening ratio and an increase in the rows of vertical cylinders. A comparison between the results of hydraulic and numerical experiments showed reasonable agreement.
Inundation Simulation Using LES-WASS-3D in the Coastal Zone
Hur, Dong-Soo ; Lee, Woo-Dong ; Yeom, Gyeong-Seon ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 34~39
The aim of this study is to investigate the inundation characteristics over coastal area due to the variation of sea level and plane arrangement of manholes using the 3D numerical model that is able to simulate directly interaction of WAve Structure Sandy beach(LES-WASS-3D). At first, The adopted model was validated through the comparison with an existing experimental data and showed fairly nice agreement. And then, the inundation characteristics over coastal area are discussed in relation to the variation of sea level and plane arrangement of manholes.
An Experimental Study on the Water Tightness of Fly Ash Antiwashout Underwater Concrete
Kwon, Jung-Hyun ; Kim, Bong-Ik ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 40~45
This paper describes the effects of fly ash replacement on the water tightness of antiwashout underwater concrete, which replaced the cement with fly ash from 0% to 30%. The experimental work was performed to find out the depth of permeation of concrete specimens cast in air and cured in 23
tap water using an open center pressure type of water permeation tester. The results showed that the permeation depth values of antiwashout underwater concrete were deeper than normal concrete, but that an admixture using fly ash during antiwashout underwater concrete casting in air made it more watertight than normal concrete according to the water permeation testing. SEM observations of the specimens of fly ash antiwashout underwater concrete showed that it wasmore packed with structures because of the pozzolan reaction of the fly ash and cement.
Characteristic Evaluation Based on the Heat Treatment Conditions of Super Duplex Stainless Steel with 0.2% N as an Additive - Part 1: Mechanical Properties and Microstructure
Ahn, Seok-Hwan ; Kang, Heung-Joo ; Nam, Ki-Woo ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 46~50
Super duplex stainless steel has along life in severe environments because of its strength and corrosion resistance. If 0.2
0.3% Nitrogen in aninterstitial solid solution is added, the austenite structure is reinforced. This improves the solid solution hardening and the anticorrosionability. In this study, the mechanical properties and structures of the super duplex stainless steel with the 0.2% N additive were investigated to determine the effect of various volume fractions on the austenite phase. The various volume fractions and distributions of the austenite structure in the applied test specimens were obtained by changing the heat treatment temperature and cycle. The characteristics by amounts of the
phase obtained from the precipitation heat treatment were alsoinvestigated. From the results, when the austenite volume fraction increases, the tensile strength decreases and elongation increases. And the
phase was rapidly increased by increasing the heat treatment time. When the volume fraction of the
phase increased, tensile strength increased.
Comparison of Mechanical Characteristics of Fiber-Reinforced Lightweight Soils
Kim, Yun-Tae ; Han, Woo-Jong ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 51~58
The objective of this study was to investigate the mechanical characteristics of fiber-reinforced lightweight soil using waste fishing net or monofilament for recycling both dredged soils and bottom ash. Reinforced lightweight soil consists of dredged soil, cement, air foam, and bottom ash. Waste fishing net or monoiament was added the mixture in order to increase the shear strength of the lightweight soil. Test specimens were fabricated with various mixing conditions, including waste fishing net content and monofilament content. Several series of unconfined compression tests and direct shear tests were carried out. From the experimental results, it was found that the unconfined compressive strength, as well as the stress-strain behavior of reinforced lightweight soil was strongly influenced by mixing conditions. In this study, the maximum increase in shear strength was obtained with either a 0.5% content of monofilament or 0.25% waste fishing net. The unconfined compressive strength of reinforced lightweight soil with monofilament was greater than that of reinforced lightweight soil with waste fishing net.
Properties of Liquid Phase Sintered SiC Materials Containing
Lee, Sang-Pill ; Lee, Moon-Hee ; Lee, Jin-Kyung ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 59~64
The mechanical properties of liquid phase sintered (LPS) SiC materials, with the addition of oxide powder, were investigated, in conjunction with a detailed analysis of their microstructures. LPS-SiC materials were fabricated at a temperature of 1820
under an argon atmosphere, using three different starting sizes of SiC particles. The sintering additive for the fabrication of the LPS-SiC materials was an
mixture with a constant composition ratio (
: 1.5). The particle sizes of the commercial SiC powderswere 30 nm, 0.3
m, and 3.0
m. The flexural strength of the LPS-SiC materials was also examined at elevated temperatures. A decrease in the starting size of the SiC particles led to an increase in the flexural strength of the LPS-SiC materials, accompanying a highly dense morphology with the creation of a secondary phase. Such a secondary phase was identified as
. The flexural strength of the LPS-SiC materials greatly decreased with an increase in the test temperature, due to the creation of a large amount of pores.
In-Plane Collision Analysis of Perforated Steel Plates
Kang, Dong-Baek ; Lee, Ju-Won ; Na, Won-Bae ; Kim, Jeong-Tae ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 65~71
In many cases, open-type plate breakwaters use plates with multiple holes; the holes serve as energy dissipaters and weight reducers. Because of the multi-holes configuration, stress concentration should be considered during the design process. Among several design loading conditions, the loads from a possible collision with a man-made vessel or other unexpected events many damage a multi-perforated steel plate. In that case, the structural behavior of a multi-perforated steel plate is quite significant, and is not well understood. This study presents a collision analysis for a multi-perforated steel plate. First, four different perforation topologies (three with circles and one with squares) were selected to investigate the effect of different hole shapes on the structural response. Second, the wave force at a specific site was calculated and loaded onto a steel plate as a static load. The static stresses were used for reference values. Third, two rigid body impacters (cubical & cylindrical) were applied to the steel plates to investigate the transient stress responses. In addition, two different impacting angles (
) were selected to investigate the angle effect. From the collision analysis, the significance of the transient stresses was emphasized.
Review of Deepwater Petroleum Exploration & Production
Choi, Han-Suk ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 72~77
General aspects of deepwater petroleum exploration and production were identified and related technical challenges were addressed. Historical perspectives, insight, processes, and engineering applications are reviewed to enhance the design capability of the domestic offshore industry. The technical challenges and unique aspects of deepwater exploration and production were identified. The assessment of deepwater exploration, drilling, and production systems is a key stage for performing the front end engineering design (FEED). The global trends in deepwater development, including the feasibility for Korea, were reviewed.
A Study on Development of a Marine Docking System for Repair of a Small Coast-Boat
Park, Chung-Hwan ; Jang, Dong-Won ; Yang, Hyang-Kweon ; Jin, Jong-Ryung ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 78~83
In recent years, small boats used for marine leisure have been steadily increasing because of the increase in national income and the desire for marine leisure. But the repair of such small boats in dry dock has pointed out many faults in small FRP-shipbuilding in terms if workspace and manpower. Lifting a boat from the water to land is done with a crane or by hand using a sling around the bottom of the boat. But dry dock work is limited by the scale of the boat, which corresponds to the crane capacity, with carelessness making it possible to capsize a boat and endanger life. The purpose of this study was the development of a marine docking system that would improve economical efficiency and safety, for which we carried out concept design, model tests, structural analysis, etc.
A Study on the Anti-rolling Effect of Stem Sub-body in the Stepped-Hull Planing Boat
Kang, Byung-Yoon ; Park, Chung-Hwan ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 84~89
It is hard to find experimental data for a model test of small high-speed planning boats. It is difficult to verify the performance seen in a model test for a high-speed boat because the ship-model scale-ratio is very small and the flow velocity of the circulating water channel and the X-carriage speed of the towing tank are restricted. Therefore most hull-form designs for high-speed small boats depend on the sea-trial test result for similar boats or evaluation through numerical calculations. This study investigated the anti-rolling effect of the stern sub-body in a 50-knot doss planning boat. To carry out this work, new model test procedures were set up in the actual sea. Using this method, the anti-rolling effect of the stern sub-body was investigated. A stern sub-body attached to a planning boat was proved to be effective in reducing the roll and pitch angle.
A Development of Anti-sway System for Real Application: Measurement and Control of Crane Motions Using Camera
Kawai, Hideki ; Kim, Young-Bok ; Choe, Yong-Woon ; Yang, Joo-Ho ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 90~96
In general, the swing motions of a crane are controlled and suppressed by controlling the trolley motion. In many of our previous studies, we suggested a new type of anti-sway control system for a crane. In this proposed control system, a small auxiliary mass (moving-mass) is installed on the spreader and moving this auxiliary mass controls tire swing motion. The actuator reaction against the auxiliary mass applies inertial control forces to the container in order to reduce the swing motion in the desired manner. However, measuring systems based on a laser sensor or other means are not veryuseful in real-worldapplications. So, in this paper, animage sensor is used to measure the motions of the spreader and the measured data are fed back to the controller in real time. The applied image processing technique is a kind of robust template matching method called Vector Code Correlation (VCC), which was devised to consider real environmental conditions. The H
based control technique is applied to suppress the swing motion of the crane. Experimental results showed that the proposed measurement and control system based on an image sensor is useful and robust to disturbances.
Estimation of the Hydrodynamic Coefficients for the Deep-sea UUV "HEMIRE"
Baek, Hyuk ; Kim, Ki-Hun ; Jun, Bong-Huan ; Lee, Pan-Mook ; Lim, Yong-Kon ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 97~105
This paper represents the experimental identification of a finite-dimensional dynamical plant model for the HEMIRE Remotely Operated Vehicle. The experiments were conducted during sea trials in the East Sea in October 2006 and peer testing by the South Sea Research Institute in January 2007. A least-squares method was employed to identify decoupled single degree-of-freedom plant dynamical models for the X, Y, Z and heading degree-of-freedom from experimental data. The performance of the identified plant dynamical model was evaluated by directly comparing simulations of the identified plant model to the experimentally observed motion data from the actual vehicle.
Underwater Navigation of an Autonomous Underwater Vehicle Using Range Measurements from a Fixed Reference Station
Lee, Pan-Mook ; Jun, Bong-Huan ; Lim, Yong-Kon ;
Journal of Ocean Engineering and Technology, volume 22, issue 4, 2008, Pages 106~113
This paper presents an underwater navigation system based on range measurements from a known reference station fixed on the sea bottom or floated at surface with a buoy, for which the system is extended to 3-dimensional coordinates. We formulated a state equation in polar coordinates and constituted an extended Kalman filter for discrete-time implementation of the navigation algorithm. The autonomous underwater vehicle, lSiMl, cruising with a constant speed can estimate its trajectory using just range measurements and additional depth, heading and pitch sensors. Simulation studies were performed to evaluate the underwater navigation of the maneuvering AUV with range measurements. We modulated the sample rate of range measurements to evaluate the effect of the update rate, and changed the initial position error of the AUV to check the robustness to estimation errors. Simulation results illustrates that the extended navigation system provides convergence of the state estimates. The navigation system was conditionally stable when it had initial position errors.