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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Advanced Research in Ocean Engineering
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Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 1, Issue 4 - Dec 2015
Volume 1, Issue 3 - Sep 2015
Volume 1, Issue 2 - Jun 2015
Volume 1, Issue 1 - Mar 2015
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A Study on Remaining Efficiency of Thermal Straightening after Block Lifting
Ha, Yunsok ; Yi, Myungsu ;
Journal of Advanced Research in Ocean Engineering, volume 1, issue 3, 2015, Pages 148~156
DOI : 10.5574/JAROE.2015.1.3.148
Deck plates of ships or offshore structures would make out-of-plane distortion for their thin thickness. These distortions are usually straightened by thermal straightening such as flame heating method. After thermal straightening, the blocks are lifted and moved by cranes to assemble it at dry-dock stage. After this lifting process, out-of-plane deformation again happens frequently. And then, they continuously cause quality and accuracy problems in the final dry-dock process. So, it takes more time for repair and correction working. According to preceding research, the lifting process by cranes would offset the effect on thermal straightening. The target of this study is to develop a methodology analyzing the remaining efficiency of thermal straightening after block lifting. The development was based on the assumption of yield state at straightening region. Therefore the remaining efficiency was obtained by different stiffness slope while lifting & relieving. The efficiency formula was designed using inherent strain, and we made a table of zero-efficiency by cooling speed and class rule's steels. As a result, if the stress orthogonal to straightened line is calculated during lifting analysis by FEA, the efficiency can be obtained linearly to the values in the table. Finally, even optimized carling position can be designed by considering the regional data from series project and welding region on deck.
An Analytical Solution for Regular Progressive Water Waves
Shin, JangRyong ;
Journal of Advanced Research in Ocean Engineering, volume 1, issue 3, 2015, Pages 157~167
DOI : 10.5574/JAROE.2015.1.3.157
In order to provide simple and accurate wave theory in design of offshore structure, an analytical approximation is introduced in this paper. The solution is limited to flat bottom having a constant water depth. Water is considered as inviscid, incompressible and irrotational. The solution satisfies the continuity equation, bottom boundary condition and non-linear kinematic free surface boundary condition exactly. Error for dynamic condition is quite small. The solution is suitable in description of breaking waves. The solution is presented with closed form and dispersion relation is also presented with closed form. In the last century, there have been two main approaches to the nonlinear problems. One of these is perturbation method. Stokes wave and Cnoidal wave are based on the method. The other is numerical method. Dean's stream function theory is based on the method. In this paper, power series method was considered. The power series method can be applied to certain nonlinear differential equations (initial value problems). The series coefficients are specified by a nonlinear recurrence inherited from the differential equation. Because the non-linear wave problem is a boundary value problem, the power series method cannot be applied to the problem in general. But finite number of coefficients is necessary to describe the wave profile, truncated power series is enough. Therefore the power series method can be applied to the problem. In this case, the series coefficients are specified by a set of equations instead of recurrence. By using the set of equations, the nonlinear wave problem has been solved in this paper.
An Experimental Investigation on Reduction of List Angle of a Semi-submersible Platform in Head Sea
Kim, Nam Woo ; Nam, Bo Woo ; Choi, Young Myung ; Hong, Sa Young ;
Journal of Advanced Research in Ocean Engineering, volume 1, issue 3, 2015, Pages 168~175
DOI : 10.5574/JAROE.2015.1.3.168
This study consists of an experimental investigation of the reduction of the second-order roll motion of a semi-submersible platform in head sea conditions by adding hull damping. The second-order heave drift force and roll drift moment are known to be the main triggers that induce the list angle (Hong et al., 2010). Hong et al. (2013) used numerical calculations to show the possibility of reducing the list angle by changing the pontoon shape and adding a damping device on the hull. One of their findings was that the reduction in the list angle due to the increase in pontoon surface damping was significant. A series of model tests were carried out with a 1:50 scaled model of semi-submersible at the KRISO wave basin. The experiments indicated that adding damping on the hull surface effectively suppressed the list angle.
Preliminary Design and Performance Analysis of Ducted Tidal Turbine
Jo, Chul-Hee ; Lee, Kang-Hee ; Kim, Do-Youb ; Goo, Chan-Hoe ;
Journal of Advanced Research in Ocean Engineering, volume 1, issue 3, 2015, Pages 176~185
DOI : 10.5574/JAROE.2015.1.3.176
Recently, focus has been placed on ocean energy resources because environmental concerns regarding the exploitation of hydrocarbons are increasing. Tidal current power, one of the ocean energy resources, has great potential worldwide due to its high energy density. The flow velocity is the most crucial factor for the power estimation of TCP(Tidal Current Power) system since the kinetic energy of the flow is proportional to the cube of the flow speed. So sufficient inflow speed to generate electricity from the tidal current power is necessary. A duct system can accelerate the flow velocity, which could expand the applicable area of TCP systems to relatively lower velocity sites. The shapes of the inlet and outlet could affect the flow rate inside the duct. To investigate the performance of the duct, various ducts were preliminary designed considering the entire system that is single-point moored TCP system and a series of simulations were carried out using ANSYS-CFX v13.0 CFD software. This study introduces a ducted turbine system that can be moored to a seabed. A performance estimation and comparison of results with conventional tidal converters were summarized in this paper.
A Study on Statistical Analysis of Local Ice Loads Measured during the Arctic Voyage of the IBRV ARAON
Kwon, Yong-Hyeon ; Choi, Kyungsik ; Lee, Tak-Kee ;
Journal of Advanced Research in Ocean Engineering, volume 1, issue 3, 2015, Pages 186~197
DOI : 10.5574/JAROE.2015.1.3.186
In summer 2010, field measurements of local ice loads were carried out in the Arctic Ocean using the Korean first icebreaking research vessel, ARAON. In some previous studies by the authors, several investigations for the data measured at 2010 including the relationship between the measuring points and ice loads, the possibility for observation of higher ice load and the relationship between the ship speed and ice loads were reported. During 10 days in August 2013, new field measurements were performed in similar waters of the Arctic Ocean using the same vessel, ARAON. The aim of this study is to investigate the statistical properties of 2013 measurements and compare results by two periods.