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 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
Numerical Analysis of Wave Field in OWC Chamber Using VOF Model
Liu, Zhen ; Hyun, Beom-Soo ; Jin, Ji-Yuan ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 1~6
Recently Oscillating Water Column (OWC) plants have been widely employed in wave energy conversion applications. It is necessary to investigate the chamber and optimize its shape parameters for maximizing air flow and energy conversion due to wave conditions. A 2D numerical wave tank based on a Fluent and VOF model is developed to generate the incident waves and is validated by theoretical solutions. The oscillating water column motion in the chamber predicted by the numerical method is compared with the available experimental data. Several geometric scales of the chamber are calculated to investigate the effect of the shape parameters on the oscillating water column motion and wave energy conversion.
A Far Field Solution of the Slowly Varying Drift Force on an Offshore Structure in Bichromatic Waves - Two Dimensional Problems
Lee, Sang-Moon ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 7~12
A far field solution of the slowly varying force on an offshore structure by gravity ocean waves was shown as a function of the reflection and transmission of the body disturbed waves. The solution was obtained from the conservation of the momentum flux, which simply describes various wave forces, while making it unnecessary to compute complicated integration over a control surface. The solution was based on the assumption that the frequency difference of the bichromatic incident waves is small and its second order term is negligible. The final solution is expressed in term of the reflection and transmission waves, i.e. their amplitudes and phase angles. Consequently, it shows that not only the amplitudes but also the phase differences make critical contributions to the slowly varying force. In a limiting case, the slowly varying force solution gives the one of the mean drift force, which is only dependent on the reflection wave amplitude. An approximation is also suggested in a case where only the mean drift force information is available.
A Review of the Expansion Behavior of Marine Pipelines
Choi, Han-Suk ; Lee, Seung-Keon ; Chun, Eun-Jee ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 13~19
A camprehensive review of the expansion behavior of marine pipelines due to thermal and pressure change is presented based on research work over the last 10 years. The review is organized into five main sections, namely free expansion with uniform temperature, free expansion with temperature gradient, expansion with end restraints, expansion of pipe-in-pipe system, and lateral deviation (snaking). Based on the accumulated knowledge of the interactions between the soil and pipeline behavior, a whole pipeline system can be modeled by an accurate finite element method (FEM). This methodology requires a comprehensive understanding and engineering verification of the expansion behavior of marine pipelines.
Numerical Simulation of Two-dimensional Floating Body Motion in Waves Using Particle Method
Jung, Sung-Jun ; Park, Jong-Chun ; Lee, Byung-Hyuk ; Ryu, Min-Cheol ; Kim, Yong-Soo ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 20~27
A moon-pool is a vertical well in a floating barge, drilling ship, or offshore support vessel. In this study, numerical simulation of two-dimensional moon-pool flaw coupled with a ship's motion in waves is carried out using a particle method, the so-called MPS method. The particle method, which is recognized as one of the gridless methods, was developed to investigate nonlinear free-surface motions interacting with structures. The method is more feasible and effective than convectional grid methods in order to solve a flaw field with complicated boundary shapes.
Coastline Evolution Analysis and Forecast due to the Construction of Groin at Heoya-River Mouth Area
Kim, Seong-Deuk ; Kang, Kyung-Ho ; Park, Hae-Sung ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 28~33
From the 1997 to January, 2004, a groin 156m long was constructed at the mouth of the Heoya river-mouth as a protection and barrier. To understand the changes to Jinha beach from the blockade of the river mouth, several aerial photographs, etc., were compared, which showed that the changes were significant. Comparing these results to the state of the area before construction of the groin, the blockade of the river was relaxed, but the formation of the tombolo, in the middle groin area was accelerated and the total Jinha beach erosion and especially the erosion of the southern part of Jinha beach was developed. But according to statements by residents and some current documents, the blockade of the Heoya-river mouth is still underway at the surrounding areas of the groin and chronic dredged sand has been used for littoral nourishment at the northern part of the middle groin and on Jinha beach. The result of numerical simulation based on the present state shows that if this sort of dredging is stopped, the sand accumulation will progress near the river mouth groin and the existing tombolo at the middle groin will progress to the north and severe erosion will occur at the southern coastline near the middle groin and the farthest southern part of Jinha beach, and Jinha beach itself will experience a gradual erosion. The main reason for these erosions should be the typhoons that are happening during the summer season. To provide protection from these kinds of undesirable erosions, a total of 23 numerical simulations have been done. It has been shown that submerged breakwaters at the front area of the beach will be efficient to protect from main beach erosion, but there should be alternative proposals for the influence of the river mouth blockade.
A Numerical Prediction for Water Quality at the Developing Region of Deep Sea Water in the East Sea Using Ecological Model
Lee, In-Cheol ; Yoon, Seok-Jin ; Kim, Hyeon-Ju ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 34~41
As a basic study for developing a forecasting/estimating system that predicts water quality changes when Deep Sea Water (DSW) drains to the ocean after using it, this study was carried out as follows: 1) numerical simulation of the present state at DSW developing region in the East sea using SWEM, 2) numerical prediction of water quality changes by effluent DSW, 3) analysis of influence degree 'With defined DEI (DSW effect index) at F station. On the whole, when DSW drained to the ocean, Chl-a, COD and water-temperature were decreased and DIN, DIP and DO were increased by effluent DSW, and Salinity was steady. According to analysis of influence degree, the influence degree of DIN was the highest and it was high in order of Chl-a, COD, Water-temperature, DO, DIP and Salinity. The influence degree classified by DSW effluent position was predicted that suiface outflow was lower than bottom outflow. Ad When DSW discharge increased 10 times, the influence degree increased about
A Study of Cold Room Experiments for Strength Properties of Frozen Soil
Seo, Young-Kyo ; Kang, Hyo-Sub ; Kim, Eun-Sub ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 42~49
Recently many countries have become interested in the development of cold or arctic regions. The construction of engineered structures in those regions demands an understanding of the deformation characteristics of frozen soil. However, an understanding of frozen soil behavior poses difficult problems owing to the complex interaction between the soil particles and the ice matrix. In this research, a series of laboratory tests was performed to investigate the variations in the unconfined compression strength and split tensile strength of weathered granite soil and mixed soil (standard sand and kaolinite) in 15 degrees below zero environments. In the frozen soil tests, specimens were prepared with various water and clay contents, and then the interrelationships between four factors (water content, clay content, unconfined compression strength, split tensile strength) were analyzed. The test results were summarized as follows; as the water content was increased, the unconfined compressive and split tensile strengths also increased in frozen soil. However as the clay content was increased, the unconfined compressive and split tensile strengths were lowered. In the case of frozen soil that contained little clay content, the strength decreased rapidly in mixed soil (standard sand and kaolinite) when the frozen specimen was broken. On the other hand, in the cases of mixed soil that contained a high clay content and weathered granite soil, the strength decreased relatively slowly.
Effect of Weld Improvement on the Corroded Fatigue Life of Welded Structures
Im, Sung-Woo ; Chang, In-Hwa ; Kim, Sang-Shik ; Song, Ha-Cheol ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 50~57
The effect of weld improvement on the corroded fatigue life of welded structures was investigated. Toe grinding, TIG dressing and weld profiling were used as the geometric improvement methods. Fatigue tests under the corroded condition in artificial seawater were carried out to investigate the corrosion fatigue behavior of API 2W Gr.50T steel plate produced by POSCO. The test results in weld improved conditions were compared with those in as-welded condition. The test results were also compared with the design curves in UK DEn Class F. Corroded fatigue life of weld improved specimens was longer than that of as-welded specimen. Especially, the corroded fatigue life exceeded the mean SN curve in air of UK DEn Class F.
A Study on the Fatigue Life of Large-Scale Tubular K-joints
Im, Sung-Woo ; Chang, In-Hwa ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 58~64
Large-scale tests of welded tubular K-joint sunder balanced in-plane bending braces were carried out to observe the fatigue behavior of the API 2W Gr.60 steel plate produced by POSCO. Toe grinding and weld profiling were used to improve the fatigue life of a tubular K-joint. The effects of the steel grade and chord wall thickness on the fatigue life were also investigated. The present results were compared with the UK DEn design curve.
A Study of a Wideband Acoustic Transducer for Underwater Communication Using 1-3 Type Piezoelectric Transducer
Lee, Kyung-Woo ; So, Hyoung-Jong ; Lim, Sil-Mook ; Kim, Won-Ho ; Cho, Wun-Hyun ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 65~71
Recently, many researches in relation to data transmission with faster speed and greater volume, many researches have been carried out on sonar systems for underwater communication. According to these researches, an acoustic transducer for underwater communication requires wide bandwidth properties. In domestic researches for underwater communication sonar, an operating frequency in the range of
is used. In this paper, we propose anon-resonance type acoustic transducer for underwater communication. The TVR (transmitting voltage response) characteristics increased linearly as the frequency increased, and the RVS (receiving voltage sensitivity) characteristics were constant as the frequency increased. Traditional techniques for wide bandwidth transducershave a limit and a transmission loss difference at lower and higher frequency operating ranges. In this paper, the new transducer proposed decreased the transmission loss under some conditions. It was optimized with the FE analysis tool (ATILA) and evaluated using the TVR and the RVS characteristics in the range of
. The value of TVR was 138 dB at 20 kHz and 148 dB at 40 kHz, and the differences was 12 dB. The value of RVS was
and nearly constant. From theseresults, it is certain that the developed transducers can be used for an underwater communication network in the 1.3 km range with both a 20 kHz bandwidth and 30 kHz center frequency.
The Study of Infrared Thermography of a Mild Steel for Nondestructive Evaluation
Han, Jeong-Seb ; Park, Jin-Hwan ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 72~77
The application of infrared thermography for detecting defects under the surface of a material was studied. Defects in a specimen were made by back-drilled circular holes. To get alarge temperature difference at the surface, a halogen lamp was used for surface heating. We confirmed that the defect location had a good relationship with the maximum temperature difference. The sizes of the defects could be calculated by means of the FWHM. The value of the FWHM of a temperature difference decreased with time. Therefore in an extremely short time after the heating, the true defect size could be measured.
An Interactive Design System for Construction of Superyacht Profiles based on Freeform Curve Functionality
Nam, Jong-Ho ; Kim, Dong-Ham ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 78~84
As a preliminary step to build a complete superyacht hull design program, the development of superyacht profile design system is introduced. The two-dimensional hull profile is decomposed into four local zones depending upon the functionality and connecting continuity of the profile. Characteristics of each zone are investigated and used to generate the model describing the geometric shape of zone using freeform curves. A set of design parameters is derived from the established geometric model. Generation and modification of a model are is by manipulating the chosen parameters. Four zones designed are integrated to form a final profile. An interactive design system performing all the modeling and modification processes is implemented using the graphic user interface system based an Microsoft Foundation Class and OpenCASCADE, a open graphic library. The shapes of the profiles generated by the developed design system are verified with those of built superyachts. The developed design system will be used for the construction of three-dimensional superyacht hull modeling system.
An Experimental Study on the Ultimate Longitudinal Strength of Ship Structures Damaged due to Side Collision
Lee, Tak-Kee ; Rim, Chae-Hwan ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 85~90
Ships in bad weather conditions are likely to be subjected to accidental loads, such as high bending moment, collision, and grounding. Once she has damage to her hull, her ultimate strength will be reduced. This paper discusses an investigation of the effect of collision damage on the ultimate strength of a ship structure by performing a series of collapse tests. For the experiment, five box-girder models with stiffeners were prepared with a cross section of
and a length of 900mm. Of the five, one had no damage and four had an ellipse shaped damage area that represented the shape of the bulbous bow of a colliding ship. The amount of damage size was different between models. Among the damaged models, the damage in three of them was made by cutting the plate and stiffener, and in one by pressing to represent collision damage. Experiments were carried out under a pure bending load and the applied load and displacements were recorded. The ultimate strength was reduced as the damage size increased, as expected. The one with the largest amount of damage had damage to 30% of the depth, and its ultimate strength was reduced by 19% compared to the undamaged one. The pressed one has higher ultimate strength than those that were cut. This might be due to the fact that the plate around the pressed damage area contributes to the ultimate strength, whereas the cut one has no plate to contribute.
Consideration of the Structural Strength of High Speed Aluminum Planning Boat Plate Member
Ham, Juh-Hyeok ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 91~98
In order to establish a design guide for the bottom plate structure of a 4.3 ton aluminum planning boat, the feasibilities of bottom plate scantling of the ship are investigated based on the results of structural strength analysis and a simple equation and evaluation system are developed for initial structural design purposes. This study consists of 5 steps: First, the background, necessity, and purpose of this study are explained briefly, Second, the principal dimensions of this ship, the position of the considered bottom plate members and material characteristics are introduced. Third, the equivalent design pressure concept is introduced and evaluated based on experience and experimental data. Fourth, the strength of bottom plate members are examined using elasto-plastic nonlinear structural analysis, and response levels and several boundary conditions are reviewed based on the analysis results. Finally, in order to suggest design guides in respect to the ship's structural design, a simple design equation and evaluation system for bottom plate members are suggested for boats in the 4.3 ton aluminumboat range through the introduction of safety factorsbased on the ultimate design pressure concept.
Effect of Static Load Level of Ultrasonic Nanocrystal Surface Modification Technology on Fatigue Characteristics of SKD61
Suh, Chang-Min ; Kim, Sung-Hwan ;
Journal of Ocean Engineering and Technology, volume 22, issue 2, 2008, Pages 99~105
Ultrasonic nanocrystal surface modification (UNSM) is a method to induce severe plastic deformation to a material surface, so that the structure of the material surface becomes a nanocrystal structure from the surface to a certain depth. It improves the mechanical properties, namely hardness, compressive residual stress, and fatigue characteristics. Specimens of SKD61 were tested to verify the effects of the variation of UNSM static load level on fatigue characteristics. The results were as follows: the grain size of SKD61 treated with UNSM became very fine from the material surface to a
depth. The surface hardness of SKD61 was increased up to 37% after UNSM. And fatigue strength at
cycles was increased by 8.3, 11.2, and 17.9% respectively, when the static load levels of UNSM were 4, 6, 8 kgf.