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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
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Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 26, Issue 6 - Dec 2012
Volume 26, Issue 5 - Oct 2012
Volume 26, Issue 4 - Aug 2012
Volume 26, Issue 3 - Jun 2012
Volume 26, Issue 2 - Apr 2012
Volume 26, Issue 1 - Feb 2012
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A study on the Development of Energy-Saving Device "Crown Duct"
Lee, Kwi-Joo ; An, Jung-Sun ; Yang, Sun-Hee ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 1~4
DOI : 10.5574/KSOE.2012.26.5.001
A energy saving device "Crown duct" has been developed and its efficiency gain has been verified experimentally in the towing tank of SSPA. The preswirl stator is well known as one of energy saving devices, which recovering the rotational energy of propeller slipstream. Crown duct has two functions of recovers the rotational energy by three blades on top of duct and of flow concentration by semi-duct. The model tests showed 4.4% efficiency gain with Crown Duct at full load condition and 6.9% at ballast condition compared with the bare hull ones for the middle class tanker.
Evaluation of Microscopic Damage to TIG Welded Carbon Steel using Acoustic Emission and Ultrasonic Test
Lee, Joon-Hyun ; Lee, Jin-Kyung ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 5~10
DOI : 10.5574/KSOE.2012.26.5.005
In this study, carbon steel (A53) is used as the material for the pipes in a marine plant and ship industry. Welds are necessary to join the carbon steel, and the effect of this welding on the properties of the carbon steel has been studied by many researchers. In this study, the dynamic behavior of welded carbon steel was studied using an acoustic emission (AE) technique, which is a nondestructive test. There are numerous AE parameters that can be used to analyze the damage behavior of carbon steel by external loading. The AE parameters of energy, cumulative count, amplitude, and AE event were used, and each parameter was differentiated according to the degree of damage to the carbon steel. The energy showed a high level at the elastic range of the load curve, while the amplitude had the highest value at the hardening region. The cumulative count showed a growth tendency similar to the loading curve. In addition, an ultrasonic technique and hardness test were applied to evaluate the mechanical properties according to the base zone, HAZ region, and weld zone of the weld specimen. The velocity and attenuation ratio showed little change between zones, and an evaluation of the ultrasonic waves on each zone of the specimen was found to be a useful method to clarify the mechanical properties of the carbon steel.
Damage Detection Using Finite Element Model Updating
Min, Cheon-Hong ; Choi, Jong-Su ; Hong, Sup ; Kim, Hyung-Woo ; Yeu, Tae-Kyeong ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 11~17
DOI : 10.5574/KSOE.2012.26.5.011
In this study, a damage detection method that uses sensitivity-based finite (FE) element model updating with the natural frequency and zero frequency was proposed. The stiffness matrix for a structure was modified using the sensitivity-based FE model updating method. A sensitivity analysis was used to update the FE model, and the natural frequencies and zero frequencies were considered as target parameters to supplement the information on the vibration characteristics. The locations and values of the damages were estimated from the modified stiffness matrix. Several numerical examples were considered to verify the performance of the proposed method.
Behavior Characteristic of Shaping Formation according to Joint Type of Structures
Kim, Jin-Woo ; Eom, Jang-Sub ; Lee, Yong-Hee ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 18~24
DOI : 10.5574/KSOE.2012.26.5.018
This paper concerned with the behaviour of shaping formation and the erection for SCST structure by cable-tensioning for three kinds of structure models. The joint types of experimental models are ball type joints, bolt type joints with gusset plates, and bolt type joints. The feasibility of the proposed shaping method and the reliability of the established geometric model were confirmed with a nonlinear finite element analysis and an experimental investigation for full size scaled pyramid test model and three kinds of SCST structure models. The characteristic of the behaviour of each joint type is shown in the shaping test for practical design purposes. As a results, the behaviour characteristics of joints is very significant in shaping analysis of space structures. So the joint type should be considered in the design and analysis of the shape formation for space structures. Also, in the special field condition, it could be a fast and economical method for constructing the space structure.
Optimization of Lock-in Thermography Technique using Phase Image Processing
Cho, Yong-Jin ; Han, Song-I ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 25~30
DOI : 10.5574/KSOE.2012.26.5.025
This study examined the use of LIT (lock-in infrared thermography) to detect defects in the welded parts of ships and offshore structures. A quantitative analysis was used with the filtering and texture measurement of image processing techniques to find the optimized experimental condition. We verified the reliability of our methods by applying image processing techniques in order to normalize the evaluations of comparative images that showed a phase difference. In addition, it was found that a low to mid-range intensity of light exposure on the surface showed good results, whereas high exposure did not provide significant results. A lock-in frequency of around 0.1 Hz was satisfactory regardless of the intensity of the light source. In addition, making the integration time of the thermography camera inversely proportional to the intensity of the exposed light source during the experiment provided good results.
Analysis of Loading Rate Capacity of Plate Anchor in Sand
Ryu, Dong-Man ; Seo, Young-Kyo ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 31~39
DOI : 10.5574/KSOE.2012.26.5.031
Anchors are primarily designed and constructed to resist outwardly directed loads imposed on the foundation of a structure. These outwardly directed loads are transmitted to the soil at a greater depth by the anchors. Buried anchors have been used for thousands of years to stabilize structures. Nowadays, various types of earth anchors are used for the uplift resistance of transmission towers, utility poles, submerged pipelines, and tunnels. Anchors are also used for the tieback resistance of earth-retaining structures, waterfront structures, at bends in pressure pipelines, and when it is necessary to control thermal stress. In this research we analyzed the uplift behavior of plate anchors in sand using a laboratory experiment to estimate the uplift behavior of plate anchors under various conditions. To achieve the research purpose, the uplift resistance and displacement characteristics of plate anchors caused by the embedment ratio, plate diameter, and loading rate were studied, compared, and analyzed in various cases.
Thrust Caused by Oscillating Two-Dimensional Hydrofoil Moving in Propagating Unsteady Flow Field
Choi, Yoon-Rak ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 40~46
DOI : 10.5574/KSOE.2012.26.5.040
This paper considers a two-dimensional hydrofoil that is fully submerged and oscillating with forward speed. The flow field is assumed to be a propagating vertical velocity field. Using the perturbation theory, the problem is linearized, and the leading-order lift force is surveyed. The thrust force is analytically derived as the second-order horizontal force. As an example, the lift and thrust for a flapping flat plate in heaving and pitching modes are analyzed. The parameters affecting the thrust are listed. The thrust is expressed in terms of the quadratic transfer functions in relation to the disturbances. The quadratic transfer functions are studied parametrically to assess the most favorable thrust.
Flow Analysis around Multi-Legged Underwater Robot "Crabster" to Evaluate Current Loads
Park, Yeon-Seok ; Kim, Wu-Joan ; Jun, Bong-Huan ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 47~54
DOI : 10.5574/KSOE.2012.26.5.047
In this study, numerical simulations were performed to evaluate the current loads acting on the multi-legged underwater robot "Crabster" with a variety of incident angles using the ANSYS-CFX package. The Reynolds-averaged Navier-Stokes equations were solved to simulate the fluid flow around Crabster to calculate the forces and moments induced by incoming currents with various angles. First, to assess the posture stability of the body, the forces and moments were calculated with various incident angles when the current acted in the vertical and horizontal directions. Next, two forms of legs (box and foil types) were evaluated to determine the hydrodynamic force variation. Finally, the current forces and moments acting on the Crabster body with the legs attached were estimated.
Application of Rigid Lid Boundary Condition for Three Dimensional Flow Analysis beneath Floating Structure
Hong, Nam-Seeg ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 55~62
DOI : 10.5574/KSOE.2012.26.5.055
In this paper, the rigid lid boundary condition is applied to simulate the influence of floating structures such as ships or pontoons, and the pressure term in both the momentum equations and continuity equation are modified. The pressure of a floating structure under the free surface is dependent on the draft of the structure, generally called a ship. If the free surface is covered by a floating structure, the free surface cannot move freely. The water level should be fixed, using a rigid lid boundary condition. This boundary condition is implemented by reducing the storage area of the grid cell with a factor between zero and one. The numerical model developed by Hong (2009) is verified through a comparison with experimental results, and the influence of the reduction factor is investigated using the verified numerical model.
Development of PEID for Acquiring Maintenance Information during Product Lifecycle of Marine Vessels
Jeon, Jeong-Ik ; Lee, Jang-Hyun ; Son, Gum-Jun ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 63~72
DOI : 10.5574/KSOE.2012.26.5.063
The product lifecycle of a marine vessel can be classified into the design-production, operation-maintenance, and disposal phases. During the operation and maintenance phase, status data should be gathered from the major machinery and instruments installed on the marine vessel in order to perform efficient maintenance work. Although a PLM (product lifecycle management) system can manage the product information during the design and assembly stage, a PLM based on asset management technology is more appropriate for product information management during the operation stage. Product embedded information devices (PEIDs) are suggested for gathering real-time maintenance information during the operation and maintenance lifecycle. A PEID allows PLM to provide the capability of offering active information exchange between the lifecycle management system and equipment. This study designed a PEID to effectively obtain information and interact with a PLM system. It consists of sensors, wireless communication, and a micro-processor, which allow it to accumulate status data on the PLM system. The embedded information device and PLM enable the seamless information flow, tracking, and updating of MRO (maintenance repair and overhaul) information for a product throughout the middle of the product lifecycle.
Marco and Microscopic Observations of Fatigue Crack Growth Behavior in API 2W Gr. 50 Steel Joints
Sohn, Hye-Jeong ; Kim, Seon-Jin ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 73~80
DOI : 10.5574/KSOE.2012.26.5.073
It is well known that a considerable amount of scatter is shown in experimental results relating to fatigue crack growth even under identical and constant amplitude cyclic loading conditions. Moreover, flux cored arc welding (FCAW) is a common method used to join thick plates such as the structural members of large scale offshore structures and very large container ships. The objective of this study was to investigate the macro- and microscopic observations of the fatigue crack growth (FCG) behavior of the FCAWed API 2W Gr. 50 steel joints typically applied for offshore structures. In order to clearly understand the randomness of the fatigue crack growth behavior in the materials of three different zones, the weld metal (WM), heat affected zone (HAZ), and base metal (BM), experimental fatigue crack growth tests for each of five specimens were performed on ASTM standard compact tension (CT) specimens under constant amplitude cyclic loading. Special focus was placed on the fatigued fracture surfaces. As a result, a different behavior was observed at the macro-level, depending on the type of material property: BM, HAZ, or WM. The variability in the fatigue crack growth rate for WM was higher than that of BM and HAZ.
Hardware in Loop Simulation on Autopilot Controller with MEMS AHRS for High Speed Unmanned Underwater Vehicle
Hwang, Arom ; Yoon, Seon-Il ; Song, Jee-Hun ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 81~86
DOI : 10.5574/KSOE.2012.26.5.081
Unmanned underwater vehicles have many applications in scientific, military, and commercial areas because of their autonomy. In many cases, an underwater vehicle adopts a control algorithm based on a tactical inertial sensor for precise control. However, a control algorithm that uses a tactical inertial sensor is unsuitable for some underwater vehicle missions such as torpedo decoys. This paper proposes a control algorithm for an unmanned underwater vehicle that does not require precise control. The control algorithm proposed for an unmanned underwater vehicle adopts a low cost MEMS inertial sensor, and simulations using the specifications of the MEMS inertial sensor under development are performed to verify the control algorithm under a real environment. The results of these simulations are presented.
Development of Design Formulas for Pipe Loops Used in Ships Considering the Structural Characteristics of Curved Portions
Park, Chi-Mo ; Bae, Byoung-Il ;
Journal of Ocean Engineering and Technology, volume 26, issue 5, 2012, Pages 87~93
DOI : 10.5574/KSOE.2012.26.5.087
Many longitudinally-arranged pipes in ships are equipped with loops as a measure to reduce stresses caused by displacement loads conveyed from the hull girder bending and/or thermal loads of carried fluid of non-ambient temperature. But as the loops have some negative effects such as causing extra manufacturing cost and occupying extra space, the number and the dimensions of the loops need to be minimized. In the meanwhile, a design formula for pipe loops has been developed by modeling them as a spring element of which stresses and axial stiffness are calculated based on the beam theory. But as the beam theory turns out to be inappropriate to deal with the complex structural behavior in the curved corner portion of the loop, this paper aims at improving the previously developed design formula by adopting correction factors which can allow for the gap between the results of beam theory and a more accurate analysis. This paper adopts a finite element analysis with two-dimensional shell elements with some validation work for it. The paper ends with a sample application of the proposed formulas showing their accuracy and efficiency.