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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 29, Issue 6 - Dec 2015
Volume 29, Issue 5 - Oct 2015
Volume 29, Issue 4 - Aug 2015
Volume 29, Issue 3 - Jun 2015
Volume 29, Issue 2 - Apr 2015
Volume 29, Issue 1 - Feb 2015
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Basic Design of Deep Subsea Manifold Frame Structure for Oil Production
Park, Se-Yung ; Choung, Joonmo ;
Journal of Ocean Engineering and Technology, volume 29, issue 3, 2015, Pages 207~216
DOI : 10.5574/KSOE.2015.29.3.207
Amanifold is one of the essential subsea oil and gas production components to simplify the subsea production layout. It collects the production fluid from a couple of wellheads, transfers it to onshore or offshore storage platforms, and even accommodates water and gas injection flowlines. This paper presents the basic design procedure for a manifold frame structure with novel structural verification using in-house unity check codes. Loads and load cases for the design of an SIL 3 class-manifold are established from a survey of relevant industrial codes. The basic design of the manifold frame is developed based on simple load considerations such as the self weights of the manifold frame and pipeline system. In-house software with Eurocode 3 embedded, called INHA-SOLVER, makes it possible to carry out code checks on the yield and buckling unities. This paper finally proves that the new design of the manifold frame structure is effective to resist a permanent and environment load, and the in-house code is also adaptively combined with the commercial finite element code Nastran.
Theoretical Prediction of Vertical Motion of Planing Monohull in Regular Head Waves - Improvement of Zarnick's Nonlinear Strip Method
Zhang, Yang ; Yum, Deuk-Joon ; Kim, Dong-Jin ;
Journal of Ocean Engineering and Technology, volume 29, issue 3, 2015, Pages 217~223
DOI : 10.5574/KSOE.2015.29.3.217
In order to predict the motions of a planing hull in waves, it is necessary to accurately estimate the force components acting on the hull such as the hydrodynamic force, buoyancy, and friction, as well as the wave exciting force. In particular, based on strip theory, hydrodynamic forces can be estimated by the summation of the forces acting on each cross-section of the hull. A non-linear strip method for planing hulls was mathematically developed by Zarnick, and his formula has been used to predict the vertical motions of prismatic planing hulls in regular waves. In this study, several improvements were added to Zarnick's formula to predict the vertical motions of warped planing hulls. Based on calm water model test results, the buoyancy force and moment correction coefficients were modified. Further improvements were made in the pile-up correction. Pile-up correction factors were changed according to variations of the deadrise angles using the results found in previous research. Using the same hull form, captive model tests were carried out in other recent research, and the results were compared with the present calculation results. The comparison showed reasonably good agreements between the model tests and present calculations.
Analysis of Resistance Performance for Various Trim Conditions on Container ship Using CFD
Seo, Dae-Won ; Park, Hyun-Suk ; Han, Ki-Min ;
Journal of Ocean Engineering and Technology, volume 29, issue 3, 2015, Pages 224~230
DOI : 10.5574/KSOE.2015.29.3.224
Vessels are traditionally optimized for a single condition, normally the contract speed at the design draft. The actual operating conditions quite often differ significantly. At other speed and draft combinations, adjusting the trim can often be used to reduce the hull resistance. Changing the trim is easily done by shifting ballast water. There are several ways to assess the effect of the trim on the hull resistance and fuel consumption, including in-service measurements, model tests, and CFD. In this paper, CFD is employed for the assessment of the resistance performance according to the trim conditions. The commercial CFD code of the STAR-CCM+ is utilized to evaluate the ship’s resistance performance on a 6,800 TEU container ship. To validate of the effectiveness of STAR-CCM+, the experimental result of the KCS hull form is compared with the result from STAR-CCM+. It is found that the total resistance of the 6,8000 TEU container ship was reduced by 2.6% in the case of a 1-m trim by head at 18knots.
Experimental Study of Effect of Mooring Line Failure on Behavior of Turret-moored FPSO Ship
Hong, Jang-Pyo ; Cho, Seok-Kyu ; Seo, Jang-Hoon ; Sung, Hong-Gun ; Lee, Dong Yeop ; Park, In Bo ; Won, Young Uk ; Choi, Sung Kwon ; Kim, Dae-woong ;
Journal of Ocean Engineering and Technology, volume 29, issue 3, 2015, Pages 231~240
DOI : 10.5574/KSOE.2015.29.3.231
FPSO model tests of mooring line failure were carried out in the ocean basin at KRISO. The characteristics of the motions and mooring lines were investigated. The FPSO ship was moored using an internal turret and catenary mooring. The test model was 1/60 scale. The mooring lines were designed to satisfy the characteristics of the original mooring lines using the truncation method. The experiments were conducted under various environments: a safe wave, current and wind condition; single broken mooring line condition; and transient mode condition. The moment of the break was determined based on experimental test results. The results showed that the FPSO behavior and mooring line tensions were acceptable under the failure condition.
Flow Stress Properties of Electric Resistance Welded Small-Sized Subsea Pipeline Subjected to Temperature and Strain Rate Variations
Kim, Younghun ; Park, Sung-Ju ; Yoon, Sung-Won ; Choung, Joonmo ;
Journal of Ocean Engineering and Technology, volume 29, issue 3, 2015, Pages 241~248
DOI : 10.5574/KSOE.2015.29.3.241
A subsea pipeline for oil/gas transportation or gas injection is subjected to extreme variations in internal pressure and temperature, which can involve a strain rate effect on the pipeline material. This paper describes the flow stress characteristics of a pipeline material called API 5L X52N PSL2, using and experimental approach. High-speed tensile tests were carried out for two metal samples taken from the base and weld parts. The target temperature was 100℃, but two other temperature levels of –20℃and 0℃ were taken into account. Three strain rates were also considered for each temperature level: quasi static, 1/s, and 10/s. Flow stress data were proposed for each temperature level according to these strain rates. The dynamic hardening behaviors of the base and weld metals appeared to be nonlinear on the log-scale strain rate axis. A very high material constant value was required for the Cowper-Symonds constitutive equation to support the experimental results.
Development of Buoy-based Autonomous Surface Robot-kit
Kim, Hyun-Sik ;
Journal of Ocean Engineering and Technology, volume 29, issue 3, 2015, Pages 249~254
DOI : 10.5574/KSOE.2015.29.3.249
Buoys are widely used in marine areas because they can mark positions and simultaneously acquire and exchange underwater, surface, and airborne information. Recently, the need for controlling and optimizing a buoy's position and attitude has been raised to achieve successful communication in a heterogeneous collaborative network composed of an underwater robot, a surface robot, and an airborne robot. A buoy in the form of a marine robot would be ideal to address this issue, as it can serve as a moving node of the communication network. Therefore, a buoy-based autonomous surface robot-kit with the abilities of sonar-based avoidance, dynamic position control, and static attitude control was developed and is discussed in this paper. The test and evaluation results of this kit show the possibility of real-world applications and the need for additional studies.
Influence of Asymmetric Aerodynamic Loading on Multiple Unit Floating Offshore Wind Turbine
Bae, Yoon Hyeok ; Kim, Moo-Hyun ;
Journal of Ocean Engineering and Technology, volume 29, issue 3, 2015, Pages 255~262
DOI : 10.5574/KSOE.2015.29.3.255
The present study developed a numerical simulation tool for the coupled dynamic analysis of multiple turbines on a single floater (or Multiple Unit Floating Offshore Wind Turbine (MUFOWT)) in the time domain, considering the multiple-turbine aero-blade-tower dynamics and control, mooring dynamics, and platform motions. The numerical tool developed in this study was designed based on and extended from the single-turbine analysis tool FAST to make it suitable for multiple turbines. For the hydrodynamic loadings of floating platform and mooring-line dynamics, the CHARM3D program developed by the authors was incorporated. Thus, the coupled dynamic behavior of a floating base with multiple turbines and mooring lines can be simulated in the time domain. To investigate the effect of asymmetric aerodynamic loading on the global performance and mooring line tensions of the MUFOWT, one turbine failure case with a fully feathered blade pitch angle was simulated and checked. The aerodynamic interference between adjacent turbines, including the wake effect, was not considered in this study to more clearly demonstrate the influence of the asymmetric aerodynamic loading on the MUFOWT. The analysis shows that the unbalanced aerodynamic loading from one turbine in MUFOWT may induce appreciable changes in the performance of the floating platform and mooring system.
Two-Phase Approach to Optimal Weather Routing Using Real-Time Adaptive A* Algorithm and Geometric Programming
Park, Jinmo ; Kim, Nakwan ;
Journal of Ocean Engineering and Technology, volume 29, issue 3, 2015, Pages 263~269
DOI : 10.5574/KSOE.2015.29.3.263
This paper proposes a new approach for solving the weather routing problem by dividing it into two phases with the goal of fuel saving. The problem is to decide two optimal variables: the heading angle and speed of the ship under several constraints. In the first phase, the optimal route is obtained using the Real-Time Adaptive A* algorithm with a fixed ship speed. In other words, only the heading angle is decided. The second phase is the speed scheduling phase. In this phase, the original problem, which is a nonlinear optimization problem, is converted into a geometric programming problem. By solving this geometric programming problem, which is a convex optimization problem, we can obtain an optimal speed scheduling solution very efficiently. A simple case of numerical simulation is conducted in order to validate the proposed method, and the results show that the proposed method can save fuel compared to a constant engine output voyage and constant speed voyage.
Depth Controller Design for Submerged Body Moving near Free Surface Based on Adaptive Control
Park, Jong-Yong ; Kim, Nakwan ; Yoon, Hyeon Kyu ; Kim, Su Yong ; Cho, Hyeonjin ;
Journal of Ocean Engineering and Technology, volume 29, issue 3, 2015, Pages 270~282
DOI : 10.5574/KSOE.2015.29.3.270
A submerged body moving near the free surface needs to maintain its attitude and position to accomplish missions. It is necessary to validate the performance of a designed controller before a sea trial. The hydrodynamic coefficients of maneuvering are generally obtained by experiments or computational fluid dynamics, but these coefficients have uncertainty. Environmental loads such as the wave exciting force and suction force act on the submerged body when it moves near the free surface. Thus, a controller for the submerged body should be robust to parameter uncertainty and environmental loads. In this paper, the six-degree-of-freedom equations of motions for the submerged body are constructed. The suction force is calculated using the double Rankine body method. An adaptive control method based on an artificial neural network and proportional-integral-derivative control are used for the depth controller. Simulations are performed under various depth and speed conditions, and the results show the effectiveness of the designed controller.