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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
Journal Basic Information
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
Selecting the target year
Study on Design Optimization of Degasser Baffles using CFD
Sur, Jong-Mu ; Im, Hyonam ; Lee, In-Su ; Lee, Heesung ; Choi, Jaewoong ;
Journal of Ocean Engineering and Technology, volume 29, issue 5, 2015, Pages 331~341
DOI : 10.5574/KSOE.2015.29.5.331
A degasser is a separation unit used in drilling to separate gas from the drilling mud. The degasser used in offshore drilling was developed at an early stage of drilling. Since its development, the design of the degasser’s internal structure has been optimized, with many limitations due to the restrictions of experimental and computational performance measurement methods. Despite the recent development of CFD technology for multiphase flow analysis, CFD has only been used in a limited way for degasser internal flow analysis and design optimization. In this study, a design optimization procedure for a degasser’s internal structure design was proposed, and CFD analyses of three types of internal structural designs were performed to evaluate the separation performance. The CFD result for each design type was used for the design optimization and, as the result, an optimized design is proposed.
Seismic Reliability Analysis of Offshore Wind Turbine Support Structure
Lee, Gee-Nam ; Kim, Dong-Hyawn ;
Journal of Ocean Engineering and Technology, volume 29, issue 5, 2015, Pages 342~350
DOI : 10.5574/KSOE.2015.29.5.342
A seismic reliability analysis of the jacket-type support structure for an offshore wind turbine was performed. When defining the limit state function using the dynamic response of the support structure, numerous dynamic calculations should be performedin an approach like the FORM (first-order reliability method). This causes a substantial increase in the analysis cost. Therefore, in this paper, a new reliability analysis approach using the static response is used. The dynamic effect of the response is considered by introducing a new parameter called the peak response factor (PRF). The probability distribution of the PRF could be estimated using the peak value of the dynamic response. The probability distribution of the PRF was obtained for a set of ground motions. A numerical example is considered to compare the proposed approach with the conventional static-response-based approach.
Study on Damage Detection Method using Meta Model
Min, Cheon-Hong ; Cho, Su-Gil ; Oh, Jae-Won ; Kim, Hyung-Woo ; Hong, Sup ; Nam, Bo-Woo ;
Journal of Ocean Engineering and Technology, volume 29, issue 5, 2015, Pages 351~358
DOI : 10.5574/KSOE.2015.29.5.351
This paper presents an effective damage detection method using a meta model. A meta model is an approximation model that uses the relations between the design and response variables. It eliminates the need for repetitive analyses of computationally expensive models during the optimization process. In this study, a response surface model was employed as the meta model. The surface model was estimated using the correlation of the stiffness and natural frequencies of the structures. The locations and values of the damages were identified using a meta model-based damage detection method. Two numerical examples (a cantilever beam and jacket structure) were considered to verify the performance of the proposed method. As a result, the damages to the structures were accurately detected.
Reliability Analysis of Gravity-based Offshore Wind Turbine Foundation Considering Ocean Environmental Loads and Soil Uncertainty
Lee, Sang Geun ; Kim, Dong Hyawn ;
Journal of Ocean Engineering and Technology, volume 29, issue 5, 2015, Pages 359~365
DOI : 10.5574/KSOE.2015.29.5.359
A reliability analysis of the gravity-based foundation of anoffshore wind turbine was performed by considering the uncertainties of the design variables, including environmental loads. The limit state functions of the gravity-based foundation were defined using the response limits of the support structures suggested in the DNV standard. The wind load couldbe obtained using the GH_bladed software, and the wave load was calculated using the Morison equation. Then, the extreme distributions of the wind and wave loads were estimated by applying the peak over threshold (POT) method to the wind and wave load data. The probability distribution characteristics of the soil properties were defined with reference to a southwest coast geotechnical survey report. The reliability index was evaluated for each failure mode using a first-order reliability method.
Optimal Design of Blade Shape for 200-kW-Class Horizontal Axis Tidal Current Turbines
Seo, JiHye ; Yi, Jin-Hak ; Park, Jin-Soon ; Lee, Kwang-Soo ;
Journal of Ocean Engineering and Technology, volume 29, issue 5, 2015, Pages 366~372
DOI : 10.5574/KSOE.2015.29.5.366
Ocean energy is one of the most promising renewable energy resources. In particular, South Korea is one of the countries where it is economically and technically feasible to develop tidal current power plants to use tidal current energy. In this study, based on the design code for HARP_Opt (Horizontal axis rotor performance optimizer) developed by NREL (National Renewable Energy Laboratory) in the United States, and applying the BEMT (Blade element momentum theory) and GA (Genetic algorithm), the optimal shape design and performance evaluation of the horizontal axis rotor for a 200-kW-class tidal current turbine were performed using different numbers of blades (two or three) and a pitch control method (variable pitch or fixed pitch). As a result, the VSFP (Variable Speed Fixed Pitch) turbine with three blades showed the best performance. However, the performances of four different cases did not show significant differences. Hence, it is necessary when selecting the final design to consider the structural integrity related to the fatigue, along with the economic feasibility of manufacturing the blades.
Applications of Side Scan Sonar for Shipbuilding and Offshore Project
O, Hyeong-Sun ; Kim, Tae-Hyung ; Kwon, Soon-Do ; Kim, Sung-Rag ; Shin, Sung-Il ; Kim, Sang-Jun ; Kim, Seong-Yeop ; Woo, Jong-Sik ;
Journal of Ocean Engineering and Technology, volume 29, issue 5, 2015, Pages 373~379
DOI : 10.5574/KSOE.2015.29.5.373
Side Scan Sonar (SSS) is capable of acquiring real-time data for seabed scouring, bathymetry, mine countermeasurement, etc. In a shipyard, an SSS package is utilized to measure the water depth and find debris in the sea because a sufficient water depth and non-interruption have to be ensured before implementing an underwater installation such as a large thruster. This paper presents the application and operation method of an SSS for the construction of an offshore project.
Redundant Architectural Design of Hydraulic Control System for Reliability Improvement of Underwater Construction Robot
Lee, Jung-Woo ; Park, Jeong-Woo ; Suh, Jin-Ho ; Choi, Young-Ho ;
Journal of Ocean Engineering and Technology, volume 29, issue 5, 2015, Pages 380~385
DOI : 10.5574/KSOE.2015.29.5.380
In the development of an underwater construction robot, the reliability of the operating system is the most important issue because of its huge maintenance cost, especially in a deep sea application. In this paper, we propose a new redundant architectural design for the hydraulic control system of an underwater construction robot. The proposed architecture consists of dual independent modular redundancy management systems linked with a commercial profibus network. A cold standby redundancy management system consisting of a preprocessing switch circuit is applied to the signal network, and a hot standby redundancy management system is adapted to utilize two main controllers.
A Study on Dynamic Modeling for Underwater Tracked Vehicle
Choi, Dong-Ho ; Lee, Young-Jin ; Hong, Sung-Min ; Vu, Mai The ; Choi, Hyeung-Sik ; Kim, Joon-Young ;
Journal of Ocean Engineering and Technology, volume 29, issue 5, 2015, Pages 386~391
DOI : 10.5574/KSOE.2015.29.5.386
The mobility of tracked vehicles is mainly influenced by the interaction between the tracks and soil. When the track of a tracked vehicle rotates, there will be a slip effect between the track and the soil, which creates a track shear force and the vehicle’s driving force. In this paper, the modeling of a working tool such as a trenching cutter and a tracked vehicle that is the lower frame of a track-based operating robot was performed. In addition, a numerical simulation was executed to verify the performance of the design objectives and the motion characteristics of the combined system.
Localization of AUV Using Visual Shape Information of Underwater Structures
Jung, Jongdae ; Choi, Suyoung ; Choi, Hyun-Taek ; Myung, Hyun ;
Journal of Ocean Engineering and Technology, volume 29, issue 5, 2015, Pages 392~397
DOI : 10.5574/KSOE.2015.29.5.392
An autonomous underwater vehicle (AUV) can perform flexible operations even in complex underwater environments because of its autonomy. Localization is one of the key components of this autonomous navigation. Because the inertial navigation system of an AUV suffers from drift, observing fixed objects in an inertial reference system can enhance the localization performance. In this paper, we propose a method of AUV localization using visual measurements of underwater structures. A camera measurement model that emulates the camera’s observations of underwater structures is designed in a particle filtering framework. Then, the particle weight is updated based on the extracted visual information of the underwater structures. The proposed method is validated based on the results of experiments performed in a structured basin environment.
Estimation of Friction-torque to Improve Accuracy of Estimated Contact-force for a Walking Robot
Lee, Jonghwa ; Kang, Hangoo ; Lee, Jihong ; Jun, Bong-Huan ;
Journal of Ocean Engineering and Technology, volume 29, issue 5, 2015, Pages 398~403
DOI : 10.5574/KSOE.2015.29.5.398
This paper introduces a method to estimate the contact-force of the leg of a walking robot and proposes a solution to a shortcoming of the previous study. This shortcoming was the deteriorating performance when estimating the contact-force whenever the rotation of each joint was reversed. It occurred because the friction-torque of each joint was not considered. In order to solve this problem, a friction-torque model for a robot leg was developed based on repetitive experimentation and used to improve the contact-force estimation performance. We verified the performance of the proposed method experimentally.