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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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International Journal of Ocean System Engineering
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Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 1, Issue 4 - Dec 2011
Volume 1, Issue 3 - Sep 2011
Volume 1, Issue 2 - Jun 2011
Volume 1, Issue 1 - Mar 2011
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An experimental study on the hydro-elastic analysis of a circular cylindrical shell
Min, Cheon-Hong ; Park, Han-Il ; Teng, Bin ; Kim, Byung-Mo ;
International Journal of Ocean System Engineering, volume 1, issue 1, 2011, Pages 1~8
DOI : 10.5574/IJOSE.2011.1.1.001
Ocean structures and vehicles are exposed to severe ocean environment conditions such as waves, winds and currents. When such ocean structures and vehicles are designed, an accurate structure analysis is required to keep the system safely. Hydro-elastic analysis is one of key issues to design such structures and vehicles. In many previous investigations, numerical analyses for hydro-elastic problem have been used. In this study, an experimental analysis is carried out and the circular cylindrical shell is considered. Dynamical characteristics for a circular cylindrical shell are identified by experimental vibration analysis in air and water. The natural frequencies and mode shapes are compared in air and water to obtain hydro-elastic effects. Some interesting results are found in the variation of natural frequencies and damping ratios of the circular cylindrical shell for different water contact depths.
A computational analysis of the scarf angle on a composites repair
Kim, Yun-Hae ; Jo, Young-Dae ; Murakami, Ri-Ichi ;
International Journal of Ocean System Engineering, volume 1, issue 1, 2011, Pages 9~15
DOI : 10.5574/IJOSE.2011.1.1.009
This study examined the relationship between the scarf angle and stress distribution, and estimated the strength recovery via a finite element analysis. The following conclusions were drawn from this study. Resin will fracture due to a tensile load with a high scarf angle, which is similar to the patch repair method. An applied stress can be loaded to a repaired laminate if the scarf angle is
. The Von-Mises stress increases with decreasing scarf angle, with the exception of a scarf angle of
, where the scarf angle can indicate the rates of shear and normal stresses. Strength recovery can be better if the scarf angle is decreased to a lower angle. However, scarf machining requires more time, a high skill level and considerable expense. Therefore, a scarf angle of
is the most effective for a repair. These results may provide a guide for engineers wishing to formulate a standard for repair. The scarf angle needs to be carefully managed for a more efficient composite repair.
Controller design for an autonomous underwater vehicle using nonlinear observers
Negahdaripour, Shahriar ; Cho, So-Hyung ; Kim, Joon-Young ;
International Journal of Ocean System Engineering, volume 1, issue 1, 2011, Pages 16~27
DOI : 10.5574/IJOSE.2011.1.1.016
The depth and heading control of an autonomous underwater vehicle (AUV) are considered to follow the predetermined depth and heading angle. The proposed control algorithm was based on a sliding mode control, using estimated hydrodynamic coefficients. The hydrodynamic coefficients were estimated employing conventional nonlinear observer techniques, such as sliding mode observer and extended Kalman filter. Using the estimated coefficients, a sliding mode controller was constructed for a combined diving and steering maneuver. The simulated results of the proposed control system were compared with those of a control system that employed true coefficients. This paper demonstrated the proposed control system, and discusses the mechanisms that make the system stable and accurately follow the desired depth and heading angle in the presence of parameter uncertainty.
The deformation of a free surface due to the impact of a water droplet
Kwon, Sun-Hong ; Park, Chang-Woo ; Lee, Seung-Hun ; Shin, Jae-Young ; Choi, Young-Myung ; Chung, Jang-Young ; Isshiki, Hiroshi ;
International Journal of Ocean System Engineering, volume 1, issue 1, 2011, Pages 28~31
DOI : 10.5574/IJOSE.2011.1.1.028
An attempt was made to compute the free surface deformation due to the impact of a water droplet. The Cauchy Poisson, i.e. the initial value problem, was solved with the kinematic and dynamic free surface boundary conditions linearized. The zero order Hankel transformation and Laplace transform were applied to the related equations. The initial condition for the free surface profile was derived from a captured video image. The effect of the surface tension was not significant with the water mass used in this investigation. The computed and observed free surface deformations were compared.
Comparison of EG/AD/S and EG/AD model ice properties
Kim, Jung-Hyun ; Choi, Kyung-Sik ;
International Journal of Ocean System Engineering, volume 1, issue 1, 2011, Pages 32~36
DOI : 10.5574/IJOSE.2011.1.1.32
EG/AD/S type model ice was originally selected as the primary model ice material for the MOERI ice tank in Korea. The existence of a sugar component in the EG/AD/S mixture may cause a serious maintenance problem. In order to understand the influence of sugar in the original model ice, a series of tests with EG/AD/S and EG/AD model ices were performed, and their material properties compared. Because the target strength of model ice in the full-scale MOERI ice tank is expensive and difficult to control, tests were performed under cold room conditions using a miniature ice tank. This paper describes the material properties of EG/AD/S and EG/AD model ices, such as flexural strength, compressive strength and elastic modulus. In order to obtain the desired strength and stiffness levels for the model ice, a warm-up process was introduced.
Numerical prediction for the performance of a floating-type breakwater by using a two-dimensional particle method
Lee, Byung-Hyuk ; Hwang, Sung-Chul ; Nam, Jung-Woo ; Park, Jong-Chun ;
International Journal of Ocean System Engineering, volume 1, issue 1, 2011, Pages 37~45
DOI : 10.5574/IJOSE.2011.1.1.037
The nonlinear free-surface motions interacting with a floating body were investigated using the Moving Particle Semi-implicit (MPS) method proposed by Koshizuka and Oka  for incompressible flow. In the numerical method, more realistic Lagrangian moving particles were used for solving the flow field instead of the Eulerian approach with a grid system. Therefore, the convection terms and time derivatives in the Navier-Stokes equation can be calculated more directly, without any numerical diffusion, instabilities, or topological failure. The MPS method was applied to a numerical simulation of predicting the efficiency of floating-type breakwater interacting with waves.
A study on the simulation of water cooling process for the prediction of plate deformation due to line heating
Nomoto, Toshiharu ; Jang, Chang-Doo ; Ha, Yun-Sok ; Lee, Hae-Woo ; Ko, Dae-Eun ;
International Journal of Ocean System Engineering, volume 1, issue 1, 2011, Pages 46~51
DOI : 10.5574/IJOSE.2011.1.1.46
In a line heating process for hull forming, the phase of the steel transforms from austenite to martensite, bainite, ferrite, or pearlite depending on the actual speed of cooling following line heating. In order to simulate the water cooling process widely used in shipyards, a heat transfer analysis on the effects of impinging water jet, film boiling, and radiation was performed. From the above simulation it was possible to obtain the actual speed of cooling and volume percentage of each phase in the inherent strain region of a line heated steel plate. Based on the material properties calculated from the volume percentage of each phase, it should be possible to predict the plate deformations due to line heating with better precision. Compared to the line heating experimental results, the simulated water cooling process method was verified to improve the predictability of the plate deformation due to line heating.
Maritime radar display unit based on PC for safe ship navigation
Bae, Jin-Ho ; Lee, Chong-Hyun ; Hwang, Chang-Ku ;
International Journal of Ocean System Engineering, volume 1, issue 1, 2011, Pages 52~59
DOI : 10.5574/IJOSE.2011.1.1.052
A prototype radar display unit was implemented using inexpensive off-the-shelf components, including a nonlinear estimation algorithm for the target tracking in a clutter environment. Two custom designed boards; an analog signal processing board and a DSP board, can be plugged into an expansion slot of a personal computer (PC) to form a maritime radar display unit. Our system provided all the functionality specified in the International Maritime Organization (IMO) resolution A422(XI). The analog signal processing board was used for A/D conversion as well as rain and sea clutter suppression. The main functions of the DSP board were scan conversion and video overlay operations. A host PC was used to run the tracking algorithm of targets in clutter, using the discrete-time Bayes optimal (nonlinear, and non-Gaussian) estimation method, and the graphic user interface (GUI) software for Automatic Radar Plotting Aid (ARPA). The proposed tracking method recursively found the entire probability density function of the target position and velocity by converting into linear convolution operations.