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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
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Volume & Issues
Volume 21, Issue 6 - Dec 2007
Volume 21, Issue 5 - Oct 2007
Volume 21, Issue 4 - Aug 2007
Volume 21, Issue 3 - Jun 2007
Volume 21, Issue 2 - Apr 2007
Volume 21, Issue 1 - Feb 2007
Selecting the target year
A Study on the Numerical Calculation for Shallow Water Waves Considering the Wind Direction Characteristics of Typhoon
Lee, Kyung-Seon ; Kim, Jung-Tae ; Ryu, Cheong-Ro ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 1~6
While a typhoon is traveling, characteristics of its wind fields are continuously changing, producing severe changes in local water level and wave conditions, especially, when a typhoon comes into shallow water. However, there have not been many studies related to local typhoon effects, especially, considering real time changes of wind direction related to the coastal topography. In the study, the characteristics of the wind field by typhoon and topographical characteristics in shallow water are considered, as well as conditions of wave climate estimation. These are performed by the SWAN (Simulating waves nearshore) model, in order to estimate the growth of wave energy due to the wind field. It can be strongly suggested that the wave energy of theof an inner bay should be estimated when the direction of the bay entrance and the wind direction of the typhoon are identical. The result of the numerical calculations is in better agreement with the observed data than the result of the conventional estimation techniques.
A Simulation of Directional Irregular Waves at Chagui-Do Sea Area in Jeju Using the Boussinesq Wave Model
Ryu, Hwang-Jin ; Shin, Seung-Ho ; Hong, Key-Yong ; Hong, Seok-Won ; Kim, Do-Young ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 7~17
Based on the Boussinesq wave model, the wave distribution in the Chagui-Do sea area in Jeju was simulated by applying the directional irregular waves at an incident boundary. The time and spatial variations of monthly mean wave height and period were investigated, which aims to provide basic information on optimal sites for wave power generation. The grid size and time interval of the Boussinesq wave model were validated by examining wave distributions around a surface piercing wall, fixed at sea bottom with a constant slope. Except for the summer season, the significant wave height is dominated by wind waves and appears to be relatively high at the north sea of Chagui-Do, which is open to the ocean, while it is remarkably reduced at the rear sea of Chagui-Do because of its blocking effect on incident waves. In the summer, the significant wave height is higher at the south sea, and it is dominated by the swell waves, which is contributed by the strong south-west wind. The magnitude of significant wave height is the largest in the winter and the lowest in the spring. Annual average of the significant wave height is distinctively high at the west sea close to the Chagui-Do coast, due to a steep variation of water depth and corresponding wave focusing effect. The seasonal and spatial distribution of the wave period around Chagui-Do sea reveals very similar characteristics to the significant wave height. It is suggested that the west sea close to the Chagui-Do coast is the mast promising site for wave power generation.
Research on Wave Kinematics and Wave Loads in Breaking Wave
Lee, Soo-Lyong ; Kang, Byung-Yoon ; Lee, Byeong-Seong ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 18~24
When the wind blows strong, most waves are breaking at sea. Breaking waves occur by exceeding the limitation of wave steepness (wave height/wave length = 1/7). Because a wave of single angular frequency couldn't generate the breaking phenomena at a two-dimensional ocean engineering basin, the breaking wave can be generated by the superposition of waves with various angular frequencies based on dispersion relation. This study investigates the particle kinematics in the breaking wave and the magnitude of the breaking wave exciting force at the breaking point and breaking region. We compare the regular wave load in a regular wave, which has same specifications (wave height, period and length), with the breaking waveload. Also, the experimental results of wave exciting force and particle velocity are investigated, by comparison with the analytic results using the potential theory.
Review on Application of Wave Model for Calculation of Freeboard in Hydraulic Structure
Kim, Kyoung-Ho ; Lee, Ho-Jin ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 25~30
Most of dams and reservoirs were made from natural materials, such as soil, sand and gravel. This type of hydraulic structure has the danger of collapse by overflow during a flood. Freeboard is the vertical distance between the crest of the dam and the full supply level in the reservoir. It must be sufficient to prevent overtopping from over flow. Thus, freeboard determination involves engineering judgment, statistical analysis, and consideration of the damage that would result from the overtopping of a hydraulic structure. This study attempts to calculate the wave height in dam, which is needed for the determination of the freeboard of the dam. Chung-ju dam is selected as the study area. Using the empirical formulas, the wave heights in dam were calculated, and the results were compared with those by the SWAN model, which is a typical wave model. The difference between the calculated results from the empirical formulas and those by the SWAN model is considerably large. This is because empirical equations consider only fetch or fetch and wind velocity, while the SWAN model considers depth and topography data as well.
Wave-Induced Soil Response around Submarine Pipeline
Hur, Dong-Soo ; Kim, Chang-Hoon ; Kim, Do-Sam ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 31~39
Recently, the nonlinear dynamic responses among waves, submarine pipeline and seabed have become a target of analyses for marine geotechnical and coastal engineers. Specifically, the velocity field around the submarine pipeline and the wave-induced responses of soil, such as stress and strain inside seabed, have been recognized as dominant factors in discussing the stability of submarine pipeline. The aim of this paper is to investigate nonlinear dynamic responses of soil in seabed, around submarine pipeline, under wave loading. In order to examine wave-induced soil responses, first, the calculation is conducted in the whole domain, including wave field and the seabed, using the VOF-FDM method. Then, velocities and pressures, which are obtained on the boundary between the wave field and the seabed, are used as the boundary condition to compute the wave-induced stress and strain inside seabed, using the poro-elastic FEM model, which is based on the approximation of the Biot's equations. Based on the numerical results, the characteristics of wave-induced soil responses around submarine pipeline are investigated, in detail, inrelation to relative separate distance of the submarine pipeline from seabed. Also, the velocity field around the submarine pipeline is discussed.
An Experimental Study on Slamming Phenomenon by Forced Impact
Nahm, Jong-Ou ; Kang, Hyo-Dong ; Chung, Jang-Young ; Kwon, Sun-Hong ; Choi, Han-Suk ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 40~44
This paper presents the experimental results on slamming phenomenon. The air pressure cylinder was used to ensure repeatability of the impact. The results showed that the adopted experimental technique was excellent in terms of repeatability, compared to that of the free drop tests. The pressure time histories, magnitude of peak pressure and the behavior of jetspray were obtained. The flat specimen was tested for various incident angles. To estimate the incident speed of the specimen, a high-speed camera was used. The high-speed camera was also a useful tool in understanding the behavior.
An Analytic Solution of the Shape of an Inclined, Partially Filled Membrane Container
Choi, Yoon-Rak ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 45~50
For a long partially-filled membrane container on an incline, the analytic solution of the similarity shape is studied. The nonlinear equation is solved and its solution is expressed as elliptic integrals, which include an unknown at the point of inflection. The point of inflection is determined by using the boundary condition at the upper separating point. Some characteristic values of the universal shape are evaluated, as the functions of inclination angle and shapes are illustrated for some cases.
Effect of Local Wall Thinned Location due to Erosion-Corrosion on Fracture Behavior of Pipes
Ahn, Seok-Hwan ; Seok, Kum-Cheol ; Nam, Ki-Woo ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 51~58
This study on the effects of local wall-thinned location on the fracture behavior of pipes was carried out, and the results were compared with the analytical results. Local wall-thinning for the bending test was machined with various sizes on the outside of pipes, in order to simulate the metal loss, due to erosion/corrosion. In addition, we had carried out FE analysis for the pipes with local wall thinning on the inside, and its results were comparatively studied with that of the outside. Three-dimensional elasto-plastic analyses were able to accurately simulate fracture behaviors of inner or outer wall thinning. Fracture types, obtained from the experiments and analyses, could be classified into ovalization, local buckling and crack initiation, depending on the thinned length and thinned ratio. Based on the results, the fracture behaviors of pipes with the outer wall thinning can be applied to estimate the fracture behaviors of pipes with the inner wall thinning.
Mechanical Properties of ITO / Glass Thin Film by Indentation Method
Yoon, Han-Ki ; Kim, Do-Hyoung ; Shin, Do-Hoon ; Murakami, Ri-Ichi ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 59~63
The thin film of indium tin oxide (ITO) was prepared using the inclination opposite target type DC magnetron sputtering equipment onto the glass substrate at room temperature, using oxidized ITO with In2O3 and SnO2in a weight ratio of 9:1. The elastic modulus and hardness of the ITO thin films, prepared at different deposition conditions, were determined through anano-indentation experiment. The work pressure was varied from
. The results show that the variation of work pressure during film deposition could vary significantly, according to the elastic modulus and hardness of the ITO thin films. It also can be seen that a minimum value exists in the film resistivity for the ITO thin films, prepared according to the variation of work pressure. However, the ITO film produced at room temperature had a microstructure in which a X ray diffraction peak is not clear, regardless of the work pressure.
A Study on the Thermal and Mechanical Characteristic of Hybrid Welded Ship Structure A-grade Steel
Oh, Chong-In ; Kim, Young-Pyo ; Park, Ho-Kyung ; Bang, Han-Sur ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 64~68
Recently, there has been considerable research in the field of application of Laser-Arc hybrid welding for superstructures, such as ship-structures, transport vehicles etc. However, the study on heat distribution and welding residual stress of hybrid weld by numerical simulation leaves much to be desired. Therefore, in this study, an optimized welding condition and numerical simulation for hybrid welding, using previous numerical analysis to calculate the heat source for hybrid welding, has been analyzed. For this purpose, fundamental welding phenomena of the hybrid process, using Laser and, is investigated. In order to calculate temperature and residual stress distribution in hybrid welds, a finite element heat source model is developed on the basis of experimental results and characteristics of temperature. Residual stress distribution in hybrid welds are understood from the result of simulation, and compared with the experimental values.
Multibody Dynamic Analysis of a Tracked Vehicle on Soft Cohesive Soil
Kim, Hyung-Woo ; Hong, Sup ; Choi, Jong-Su ; Yeu, Tae-Kyeong ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 69~74
This paper is concerned about the dynamic analysis of an underwater test miner, which operates on cohesive soil. The test miner consists of tracked vehicles and a pick-up device. The motion of the pick-up device, relative to the vehicle chassis, is controlled by two pairs of hydraulic cylinders. The test miner is modeled by means of commercial software. A terramechanics model of cohesive soft soil is implemented with the software and applied to a dynamic analysis of the test miner model. The dynamic responses of the test miner are studied with respect to four different types of terrain conditions.
An Experimental Study on Relationship of Tractive Force to Slip for Tracked Vehicle on Deep-sea Soft Sediment
Yeu, Tae-Kyeong ; Park, Soung-Jea ; Choi, Jong-Su ; Hong, Sup ; Kim, Hyung-Woo ; Won, Moon-Cheol ;
Journal of Ocean Engineering and Technology, volume 21, issue 1, 2007, Pages 75~80
Measuring the ground speed and the rotation speeds of tracks is an easy and realistic method to detect the track slips. It is very advantageous if the slips can be measured and applied to real time control of the vehicle. With a proper speed, the tractive force of a tracked vehicle may be calculated from the vehicle dynamics. For the control of tracked vehicle, the relationship between the slip and the tractive force is necessary. In this paper, a series of drawbar-pull tests, in which slips of two tracks are measured under the variational draw-bar weight, is executed to directly obtain the slip-tractive force relationship. For the purpose of the test, a tractive vehicle model was manufactured, and an artificial soil was simulated by using a bentonite-water mixture.