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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Society of Naval Architects of Korea
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Journal DOI :
The Society of Naval Architects of Korea
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Volume & Issues
Volume 51, Issue 6 - Dec 2014
Volume 51, Issue 5 - Oct 2014
Volume 51, Issue 4 - Aug 2014
Volume 51, Issue 3 - Jun 2014
Volume 51, Issue 2 - Apr 2014
Volume 51, Issue 1 - Feb 2014
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Simulation of Body Motion Caused by a Solitary Wave using the FDS-HCIB Method
Shin, Sangmook ; Kim, In Chul ; Kim, Yong Jig ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 4, 2014, Pages 265~273
DOI : 10.3744/SNAK.2014.51.4.265
Wave-body interaction is simulated using a developed code based on the flux-difference splitting scheme for immiscible and incompressible fluids and the hybrid Cartesian/immersed boundary method. A free surface is captured as a moving contact discontinuity within a fluid domain and an approximated Riemann solver is used to estimate the inviscid flux across the discontinuity. Immersed boundary nodes are identified inside an instantaneous fluid domain near a moving body, then dependent variables are reconstructed at those immersed boundary nodes based on interpolation along local normal lines to the boundary. Free surface flows around an oscillating cylinder are simulated and the computed wave elevations are compared with other reported results. The generation of a solitary wave by a moving wave-maker is simulated and the time histories of wave elevations at two different points are compared with other results. The developed code is applied to simulate body motion of an elastically mounted circular cylinder as a solitary wave passes the body. The force acting on an elastically mounted cylinder is compared with the force acting on a fixed cylinder. Grid independency of the computed body motion is established based on a comparison of results using three different-size grids.
Time Series Prediction of Dynamic Response of a Free-standing Riser using Quadratic Volterra Model
Kim, Yooil ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 4, 2014, Pages 274~282
DOI : 10.3744/SNAK.2014.51.4.274
Time series of the dynamic response of a slender marine structure was predicted using quadratic Volterra series. The wave-structure interaction system was identified using the NARX(Nonlinear Autoregressive with Exogenous Input) technique, and the network parameters were determined through the supervised training with the prepared datasets. The dataset used for the network training was obtained by carrying out the nonlinear finite element analysis on the freely standing riser under random ocean waves of white noise. The nonlinearities involved in the analysis were both large deformation of the structure under consideration and the quadratic term of relative velocity between the water particle and structure in Morison formula. The linear and quadratic frequency response functions of the given system were extracted using the multi-tone harmonic probing method and the time series of response of the structure was predicted using the quadratic Volterra series. In order to check the applicability of the method, the response of structure under the realistic ocean wave environment with given significant wave height and modal period was predicted and compared with the nonlinear time domain simulation results. It turned out that the predicted time series of the response of structure with quadratic Volterra series successfully captures the slowly varying response with reasonably good accuracy. It is expected that the method can be used in predicting the response of the slender offshore structure exposed to the Morison type load without relying on the computationally expensive time domain analysis, especially for the screening purpose.
Ultimate Strength Assessment of Ship Stiffened Panel under Arctic Conditions
Kim, YangSeop ; Park, DaeKyeom ; Kim, SangJin ; Lee, DongHun ; Kim, BongJu ; Ha, YeonChul ; Seo, JungKan ; Paik, JeomKee ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 4, 2014, Pages 283~290
DOI : 10.3744/SNAK.2014.51.4.283
Environmental changes, especially global climate change, are creating new routes to reduce a shipping service distance in Arctic area. The Arctic routes are shorter than 60% of existing ways Panama or Suez canal). For this reason, ship owners prefer to navigate in Arctic area and a transportation of goods though the Arctic area is increasing. But the low temperature in Arctic condition changes the material properties. Especially, the material will be brittle and strength will increase. And an ultimate strength analysis of ship stiffened panels is changed depending on temperatures. In present study, the ultimate strength analysis of stiffened panels in double hull oil tankers is performed under various low temperatures with the material properties obtained by tensile coupon test. The analytical method as named ALPS/ULSAP was used for analysis method and 6 kinds of temperature (20, 0, -20, -40, -60 and
) were considered to investigate the effect of Arctic conditions.
Structural Safety Assessments for Viewing Window of Semi-Submersible Catamaran
Hwang, Se Yun ; Kim, Hosung ; Lee, Kyeong Hoon ; Kim, Yooil ; Lee, Jang Hyun ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 4, 2014, Pages 291~299
DOI : 10.3744/SNAK.2014.51.4.291
In the design process of ship or its comprising components, the key to the successful design is how to guarantee the structural safety satisfying the international standard and regulation, which sometimes is not clear enough to cover the detail designs. This study deals with the design procedure for submersible viewing window installed in catamaran. As the window material, the Plexiglass, a type of reinforced plastic, is considered to satisfy the design requirements of international standard. Window thickness is calculated using geometric nonlinear finite element analysis, in order to take into account possible large deformation due to low stiffness of the Plexiglass, and the results are compared with those determined by the procedure specified in ISO12216. Finally, for the validation of proposed design, the pressure test had been carried out following the procedure specified in the standard, and structural safety was checked.
Design of Mooring Lines of a Floating Offshore Wind Turbine in South Offshore Area of Jeju
Choung, Joonmo ; Kim, Hyungjun ; Jeon, Gi-Young ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 4, 2014, Pages 300~310
DOI : 10.3744/SNAK.2014.51.4.300
This paper presents a mooring design procedure of a floating offshore wind turbine. The environment data of south offshore area of Jeju collected from Korea Hydrographic and Oceanographic Administration(KHOA) are used for hydrodynamic analyses as environmental conditions. We considered a semi-submersible type floating wind turbine based on Offshore Code Comparison Collaborative Continuation(OC4) DeepCWind platform and National Renewable Energy Laboratory(NREL) 5 MW class wind turbine. Catenary mooring with studless chain is chosen as the mooring system. Important design decisions such as how large the nomial sizes are, how long the mooring lines are, how far the anchor points are located, are demonstrated in detail. Considering ultimate limit state and fatigue limit state based on 100-year return period and 50-year design life, respectively, longterm predictions of breaking strength and fatigue are proposed.
Uncertainty Assessment of a Towed Underwater Stereoscopic PIV System
Seo, Jeonghwa ; Seol, Dong Myung ; Han, Bum Woo ; Yoo, Geuksang ; Lim, Tae Gu ; Park, Seong Taek ; Rhee, Shin Hyung ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 4, 2014, Pages 311~320
DOI : 10.3744/SNAK.2014.51.4.311
Test uncertainty of a towed underwater Stereoscopic Particle Image Velocimetry (SPIV) system was assessed in a towing tank. To estimate the systematic error and random error of mean velocity and turbulence properties measurement, velocity field of uniform flow was measured. Total uncertainty of the axial component of mean velocity was 1.45% of the uniform flow speed and total uncertainty of turbulence properties was 3.03%. Besides, variation of particle displacement was applied to identify the change of error distribution. In results for variation of particle displacement, the error rapidly increases with particle movement under one pixel. In addition, a nominal wake of a model ship was measured and compared with existing experimental data by five-hole Pitot tubes, Pitot-static tube, and hot wire anemometer. For mean velocity, small local vortex was identified with high spatial resolution of SPIV, but has serious disagreement in local maxima of turbulence properties due to limited sampling rate.
Statistical Reliability Analysis of Numerical Simulation for Prediction of Model-Ship Resistance
Lee, Sang Bong ; Lee, Youn Mo ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 4, 2014, Pages 321~327
DOI : 10.3744/SNAK.2014.51.4.321
A wide scope of numerical simulations was performed to predict model-ship resistances by using STAR-CCM+ and OpenFOAM. The numerical results were compared with experimental measurements in towing tank to analyze statistical reliability of the present simulations. Based on the normal distribution of resistance errors in 113 cases of container carriers, tankers and very large crude-oil carriers, the confidence intervals of numerical error were estimated as [-2.64%,+2.32%] and [-1.82%, +1.87%] with 95% confidence in STAR-CCM+ and OpenFOAM, respectively. The resistance errors of liquefied natural gas carriers with single- and twin-skeg were confident in the ranges of [-2.51%,+2.64%] and [-2.29%, +1.46%], respectively. The grid uncertainty of resistance coefficients for KCS was also quantitatively analyzed by using a grid verification procedure. The grid uncertainty of OpenFOAM (5.1%) was larger than 4.4% uncertainty of STAR-CCM+ although OpenFOAM provided statistically more confident results than those of STAR-CCM+. It means that a grid system verified under a specific condition does not automatically lead to statistical reliability in general cases.
Computation of Pressure Fields for a Hybrid Particle-Mesh Method
Lee, Seung-Jae ; Suh, Jung-Chun ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 4, 2014, Pages 328~333
DOI : 10.3744/SNAK.2014.51.3.328
A hybrid particle-mesh method based on the vorticity-velocity formulation for solving the incompressible Navier-Stokes equations is a combination of the Vortex-In-Cell(VIC) method for convection and the penalization method for diffusion. The key feature of the numerical methods is to determine velocity and vorticity fields around a solid body on a temporary grid, and then the time evolution of the flow is computed by tracing the convection of each vortex element using the Lagrangian approach. Assuming that the vorticity and velocity fields are to be computed in time domain analysis, pressure fields are estimated through a complete set of solutions at present time step. It is possible to obtain vorticity and velocity fields prior to any pressure calculation since the pressure term is eliminated in the vorticity-velocity formulation. Therefore, pressure field is explicitly treated by solving a suitable Poisson equation. In this paper, we propose a simple way to numerically implement the vorticity-velocity-pressure formulation including a penalty term. For validation of the proposed numerical scheme, we illustrate the early development of viscous flows around an impulsive started circular cylinder for Reynolds number of 9500.
Improvement in Resistance Performance of a Medium-Sized Passenger Ship with Variation of Bulbous Bow Shape
Yu, Jin-Won ; Lee, Young-Gill ; Lee, Seung-Hee ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 4, 2014, Pages 334~341
DOI : 10.3744/SNAK.2014.51.4.334
Due to the rise of international oil prices, with the continued increase of vessel operating costs, profitability has gradually deteriorated in the some case of South Korea ferry shipping. Therefore, it is necessary to improve the resistance performance of passenger ship. Goose neck bulb can be one of the methods to improve the resistance performance of passenger ship. Goose neck bulb has been applied to passenger ships operated in Europe and large cruise line. But there is no application example in the passenger ship to be operated on a regular basis in the sea near Korea. It is needed to provide reference data that can be applied efficiently goose neck bulb on the medium-sized passenger ships. This study, intended for the medium-sized passenger ship operated short international routes, presents the design of the hull form that goose neck bulb has been applied. And the resistance performance of the designed hull confirmed by numerical simulation. The numerical simulation is performed while changing the local shape of the goose neck depending on the bulb parameters. This study finds bulb parameters and their range that can affect the resistance performance. Thus, it is possible to provide a foundation to develop the optimal design technique and regression analysis on the resistance performance and goose neck bulb.
A Study on Classification Algorithm of Arbitrary Polygon Curved Hull Plates for the Curved Hull Plates Forming
Kim, Chan Suk ; Son, Seung Hyeok ; Shin, Jong Gye ; Noh, Jackyou ;
Journal of the Society of Naval Architects of Korea, volume 51, issue 4, 2014, Pages 342~348
DOI : 10.3744/SNAK.2014.51.4.342
In general, the forming process of the curved hull plates consists of sub tasks, such as roll bending, line heating, and triangle heating. In order to complement the automated curved hull forming system, it is necessary to develop an algorithm to classify the curved hull plates of a ship into standard shapes with respect to the techniques of forming task, such as the roll bending, the line heating, and the triangle heating. In the previous research, the classification algorithm of curved hull plates was studied only about rectangle shaped plates, and other limitations were notified. In this paper, the classification algorithm is extended to classify not only rectangle shaped plates but also arbitrary polygon hull plates. The discrete curvature can be computed by using arbitrary polygon mesh which is represented by half-edge data structure and discrete differential geometry. The algorithm tests to verify the developed algorithm with sample plates of a real ship data have been performed.