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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 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
Effect of Guide Vane on the Performance of Impulse Turbine for Wave Energy Conversion
HYUN BEOM-SOO ; MOON JAE-SEUNG ; HONG SEOK-WON ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 1~7
This paper deals with the performance analysis of the impulse turbine for a owe type wave energy conversion device. Numerical analysis was performed using the commercially-available software FLUENT. This parametric study includes variation of the setting angle of the guide vane. Since parametric study at various flow coefficients requires a tremendous amount of computing time, two-dimensional cascade flow approximation was employed to determine the optimum principal particulars in a rather simple manner. A Full three-dimensional calculation was also performed for several cases to confirm the validity of the two-dimensional approach. Results were compared to other experimental data, such as Setoguchi et al. (2001)'s extensive set of data, and found that the usefulness of 2-D analysis was well demonstrated. The advantages of each method were also evaluated.
Wave Energy Distribution at Jeju Sea and Investigation of Optimal Sites for Wave Power Generation
HONG KEY-YONG ; RYU HWANG-JIN ; SHIN SEUNG-HO ; HONG SEOK-WON ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 8~15
Wave power distribution is investigated to determine the optimal sites for wave power generation at Jeju sea which has the highest wave energy density in the Korean coastal waters. The spatial and seasonal variation of wave power per unit length is calculated in the Jeju sea area based on the monthly mean wave data from 1979 to 2002 which is produced by the SWAN wave model simulation in prior research. The selected favorable locations for wave power generation are compared in terms of magnitude of wave energy density and distribution characteristics of wave parameters. The results suggest that Chagui-Do is the most optimal site for wave power generation in the Jeju sea. The seasonal distribution of wave energy density reveals that the highest wave energy density occurs in the northwest sea in the winter and it is dominated by wind waves, while the second highest one happens at south sea in the summer and it is dominated by a swell sea. The annual average of wave energy density shows that it gradually increases from east to west of the Jeju sea. At Chagui-Do, the energy density of the sea swell sea is relatively uniform while the energy density of the wind waves is variable and strong in the winter.
An Experimental Study for the Wave Exciting Force of a Truss Spar
JO HYO-JAE ; GOO JA-SAM ; CHOI HAN-SUK ; PARK JU-YONG ; OH TAE-WON ; KIM BYUNG-WOO ; HA MUN-KEUN ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 16~21
This study presents the wave forces for spar platforms. The advantage of a spar platform is that it is easy to manufacture and has excellent to motion characteristics. It is important to precisely determine the wave force acting on spar platforms for their basic design of them. We measur the wave exciting force for both the classic spar and truss spar models, and accomplish the numerical calculation using diffraction theory. The results show that experimental values have good agreement with theoretical values. However it is difficult to accurately estimate the value considering the heave plate of truss spar due to the viscosity.
Evaluation Index of Sea Water Exchange Capability of a Port
LEE JUNG LYUL ; KIM IN HO ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 22~28
A mathematical model has been developed to evaluate the capability of sea water exchanges under tidal and diffusive environments and has been verified through comparison with numerical experiments. From the mathematical analysis, this study presents the rates of sea water exchanges due to the tidal inflow and diffusion process. The port characteristic length
is the most significant evaluation index.
Numerical Analysis of the Stress on Floating Breakwater under Various Wave Conditions
CHO WON CHUL ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 29~36
Floating breakwaters have been recently studied to reduce the transmission ratio of wave energy. The numerical study shows how wave pressure and stress act on the rectangular floating breakwater under various regular wave conditions. In order to evaluate hydrodynamic pressure on the floating breakwater, the infinite element is applied to the linear wave diffraction and radiation problems. SAP2000, a structural analysis program, is used to evaluate stress on the floating breakwater.
Web-Based Collaborative Design System for Concurrent Ship Design
LEE KYUNG-HO ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 37~43
Under the concept of the global economy, the enterprises are assigning design and production environments around the world in various areas. In shipbuilding companies, a serious problem of information exchange has emerged as companies use traditional hardware and very distinct softwares that is tailored to their field of expertise. To overcome the decreased productivity resulting from the interruption of information, the concepts of simultaneous engineering and concurrent design become very significant. In this article, the concept of collaborative design based on Internet environments is described. Specifically, the core technologies necessary to achieve collaborative design environments among shipbuilding companies, ship owners, ship classification societies, model basin, and consulting companies are adopted.
A Study on Design and Implementation of Integrated Marine Data Networking and Communication System for Training-Research Ship
KIM JAE-DONG ; PARK SOO-HAN ; KIM HYUNG-JIN ; KOH SUNG-WI ; JEONG HAE-JONG ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 44~50
A small, highly-trained crew working on the ship's automation has contributed to the improvement of operations and the labor environment on board ship. However, at the same time, having a small crew adds more responsibility to the ship's officers to safely operate and manage the ship. With the use of information and computer technology, efforts are being made towards the development of a system that will concentrate important information from the various pieces of navigational equipment. The purpose of this study is to set up and implement an integrated marine data networking and communication system on the training-research ship. Information relating to navigation, engine and office automation are investigated and analyzed, and implementation methods associated with navigation, engine and management information system were designed and presented. In addition, the networking system of the navigational signal interface unit for the integrated communication system, and the data communication method between the ship and land are also discussed.
An Improved Finite Element Analysis Model of Offshore Cable-Supported Structures
KIM SUN-HOON ; SONG MYUNG-KWAN ; NOH HYUK-CHUN ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 51~57
In this study, the improved three-dimensional analysis model designed for a more accurate analysis of marine cable-supported structures, is presented. In this improved analysis model, the beam elements, of which the stability function is derived using Taylor's series expansions, are used to model space frame structures, and the truss elements. The equivalent elastic modulus of the truss elements is evaluated on the assumption that the deflection curve of a cable has a catenary function. By using the proposed three-dimensional analysis model, nonlinear static analysis is carried out for some cable-supported structures. The results are compared with previous studies and show good agreement with their findings.
A Study on Measuring the Coefficient of Earth Pressure at Rest II
SONG MU-HYO ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 58~69
In order to investigate the characteristics of the lateral earth pressure at rest, under hysteretic
conditions, seven types of multi-cyclic models have been studied, using dry sand. For this study, the new type of
apparatus was developed, and the horizontal pressure was accurately measured. The multi-cyclic models consist of primarily 3 cases: (i)
under the same loading / unloading condition, (ii) multi-cyclic loading / unloading
exceeding the maximum pre-vertical stress, and (iii) multi-cyclic loading / unloading
within the maximum pre-vertical stress. Results fromthe multi-cyclic model indicated that a single-cyclic model could be extended if the exponents for the unloading condition
and the reloading coefficients
were primarily dependent upon the type of model, number of cycles, and the relative density.
Static Strength of Internally Ring-Stiffened Tubular T-Joints
CHO HYUN-MAN ; RYU YEON-SUN ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 70~78
In order to increase the load carrying capacity of tubular structures, the joints of tubular members are usually reinforced with various reinforcement system. A stiffening method with internal ring stiffeners is effectively used for the steel tubular joint with a large diameter. In this study, the behavior of internally ring-stiffened tubular T-joints subjected to axial loading is assessed. For the parametric study, nonlinear finite element analyses are used to compute the static strength on non-stiffened and ring-stiffened T-joints. Based on the numerical results, an internal ring stiffener is found to be efficient in improving the static strength. The influence of geometric parameters has been determined, and the reinforcement effect are evaluated. Based on the FE results, regression analises are performed considering the practical size of ring stiffener. Finally strength estimation formulas for ring-stiffened tubular T-joints are proposed.
Optimal Welding Condition for the Inclined and Skewed Fillet Joints ill the Curved Block of a Ship (I)
PARK JU-YONG ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 79~83
The curved blocks which compose the bow and stem of a ship contain many skewed joints that are inclined horizontally and vertically. Most of these joints have a large fitness error and are continuously changing their form and are not easily accessible. The welding position and parameter values should be appropriately set in correspondence to the shape and the inclination of the joints. The welding parameters such as current, voltage, travel speed, and melting rate, are related to each other and their values must be in a specific limited range for the sound welding. These correlations and the ranges are dependent up on the kind and size of wire, shielding gas, joint shape and fitness. To determine these relationships, extensive welding experiments were performed. The experimental data were processed using several information processing technologies. The regression method was used to determine the relationship between current voltage, and deposition rate. When a joint is inclined, the weld bead should be confined to a the limited size, inorder to avoid undercut as well as overlap due to flowing down of molten metal by gravity. The dependency of the limited weld size which is defined as the critical deposited area on various factors such as the horizontally and vertically inclined angle of the joint, skewed angle of the joint, up or down welding direction and weaving was investigated through a number of welding experiments. On the basis of this result, an ANN system was developed to estimate the critical deposited area. The ANN system consists of a 4 layer structure and uses an error back propagation learning algorithm. The estimated values of the ANN were validated using experimental values.
Behavior of Fatigue Crack Initiation and Growth in SM45C Steel under Biaxial Loading
KIM SANG-TAE ; PARK SUN-HONG ; KWUN SOOK-IN ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 84~90
Fatigue tests were conducted on SM45C steel using hour-glass shaped smooth tubular specimen under biaxial loading in order to investigate the crack formation and growth at room temperature. Three types of loading systems, were employed fully-reserved cyclic torsion without a superimposed static tension or compression fully-reserved cyclic torsion with a superimposed static tension and fully-reserved cyclic torsion with a superimposed static compression. The test results showed that a superimposed static tensile mean stress reduced fatigue life however a superimposed static compressive mean stress increased fatigue life. Experimental results indicated that cracks were initiated on planes of maximum shear strain whether or not the mean stresses were superimposed. A biaxial mean stress had an effect on the direction that the cracks nucleated and propagated at stage 1 (mode II).
Effect of Shot-peening on Fatigue Crack Growth
SHIM DONG-SUK ; LEE SEUNG-HO ; LEE MYUNG-HO ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 91~95
In this study, to investigate the effects of shot peening on crack growth behavior, crack growth tests are conducted on spring steels and shot peened cracks. The probabilistic crack growth equation, which can represemt the sigmoidal crack growth behavior as recently reported by Kim and Shim, is used to evaluate the experimental results. The results show that fatigue cracks grows slower in the shot peened specimen than in the unpeened and, due to the compressive residual stress occurring on the specimen surface. In the case of the shot peened specimen, the initial stress intensity factor range and the fracture toughness is higher than the non-peened specimen because the compressive residual stress affects crack growth and fracture of the specimen.
A Study on Characteristics of Inconel 625 for Petroleum Application by FCAW Process ; Effect of Shield Gases Change Influence on a Mechanical Properties
PARK KEYUNG-DONG ; JIN YOUNG-BEOM ; PARK HYOUNG-DONG ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 96~100
Inconel 625 is useful in a variety of industrial applications because of the resistance to attack in various corrosive media at temperatures from
, in combination with good low and high temperature mechanical strength. Rencently this material has also been widely used in offshore processing piping in order to extend the maintenance term and improve the quality of anti-corrosion. In general, high quality weldings for this material are readily produced by commonly used processes. How, not all processes are applicable to this material group of Ni-alloys. Metallurgical or the unavailability of matching, position or suitable welding processes produce a lower quality. Nowadays, the flux cored wire is developed and applied for increased productivity in several welding positions, including the vertical position. In this study, the weldability and weldment characteristics(mechanical properties) of inconel 625 are considered in FCAW(Flux Core Arc Welding) associated with the several shielding gases
in view of welding productivity.
Design Criteria of a Future Container Crane for Megaships
LEE SUK-JAE ; HONG KEUM-Shik ;
Journal of Ocean Engineering and Technology, volume 18, issue 6, 2004, Pages 101~107
In this paper, the design criteria of future container crane for megaships are investigated. The current loading/unloading capacity of a typical container crane, roughly 30 moves/hr, is too law to meet the requirements of future super containerships, which are expected over 15,000 TEU. After examining the transition of containerships through the years and studying the research trend in developed countries, the specifications of the container crane that can Meet a 15,000 TEU containership are proposed. The structure, trolley and hoist mechanism, outreach, backreach, capacity, speeds, durability, and stability of the future container crane are described.