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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 50, Issue 6 - Dec 2013
Volume 50, Issue 5 - Oct 2013
Volume 50, Issue 4 - Aug 2013
Volume 50, Issue 3 - Jun 2013
Volume 50, Issue 2 - Apr 2013
Volume 50, Issue 1 - Feb 2013
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Natural Frequency Analysis of Cantilever Plates with Added Mass
Jang, Hyun-Gil ; Nho, In Sik ; Hong, Chang-Ho ; Lee, Chang-Sup ;
Journal of the Society of Naval Architects of Korea, volume 50, issue 1, 2013, Pages 1~7
DOI : 10.3744/SNAK.2013.50.1.1
The high-skewed and/or composite propellers of current interests to reduce the ship vibration and to increase the acoustic performance are likely to be exposed to the unexpected structural problems. One typical example is that the added mass effect on the propellers working in the non-uniform wake field reduces the natural frequency of the propeller leading to the resonance with the low-frequency excitation of the external forces. To avoid this resonance problem during the design stage, the technique of fluid-structure interaction has been developed, but the higher-order effect of the blade geometry deformation is not yet considered in evaluating the added mass effects. In this paper the fluid boundary-value problem is formulated by the potential-based panel method in the inviscid fluid region with the velocity inflow due to the body deformation, and the structural response of the solid body under the hydrodynamic loading is solved by applying the finite element method which implements the 20-node iso-parametric element model. The fluid-structure problem is solved iteratively. A basic fluid-sturcture interaction study is performed with the simple rectangular plates of thin thickness with various planform submerged in the water of infinite extent. The computations show good correlation with the experimental results of Linholm, et al. (1965).
Experimental Study of Excessive Yaw Motion of Turret Moored Floating Body
Cho, Seok-Kyu ; Sung, Hong-Gun ; Hong, Jang-Pyo ; Choi, Hang-Shoon ;
Journal of the Society of Naval Architects of Korea, volume 50, issue 1, 2013, Pages 8~13
DOI : 10.3744/SNAK.2013.50.1.8
Excessive yaw motion of a turret moored vessel was examined in this paper. The vessel was moored by an internal turret and catenary mooring lines. The experiments were conducted in regular waves. Turret moored vessel can oscillate from side to side or move to one particular direction, and eventually exhibit large yaw motion. The results showed that the excessive yaw occured for specific condition, ratio of wave lengths and vessel length. It was found that turret moored floating vessel was unstable for regular wave period from 14 to 18 sec and excessive yaw occurred to maximum 50 deg. The time series, trajectory, phase plot and qualitative analysis are performed. The analysis showed that the results of experiments agreed with the that of analytic method and the excessive yaw could be predicted by the stability analysis.
Development of a Factory Layout Design System using Leisure-Boat Building Process
Lee, Dong-Kun ; Jeong, Yong-Kuk ; Shin, Jong-Gye ;
Journal of the Society of Naval Architects of Korea, volume 50, issue 1, 2013, Pages 14~24
DOI : 10.3744/SNAK.2013.50.1.14
The marine leisure industry in Korea has been the focus of the power of economic growth and the creation of jobs in recent years. In this regard, many studies concerning marine leisure are on-going in various fields. In this paper, developed a layout system and algorithm can resolve the factory and facility layout problem. For a layout design of leisure-boat factories, the leisure-boat production process is analyzed in order to derive standard production space elements for the layout of the factory. Based on the results, a draft design of the factory layout is carried out based on the manpower planning data, as well as the characteristics and relationships of each process data. A layout design of this paper can be verified through a factory simulation solution and we suggest the verification method using a SBD(simulation based design) methodology. The layout system takes into account the user`s accessibility and extendibility, so it is web-oriented and uses RIA (rich Internet Application) technology. Furthermore, the system and layout algorithm of this paper are verified with samples data that show the efficient factory arrangement and practical application method.
A Study to Improve the Lift Performance of a Full Spade Rudder with the Coanda Effect
Seo, Dae-Won ; Lee, Seung-Hee ;
Journal of the Society of Naval Architects of Korea, volume 50, issue 1, 2013, Pages 25~32
DOI : 10.3744/SNAK.2013.50.1.25
The shape of a conventional full spade rudder has been modified to implement the Coanda effect and consequential changes in the flow characteristics are carefully examined to show the significant enhancement in the lift performance. A preliminary numerical study has been done to identify the optimum configuration of the modified rudder sections. For the purpose, chord wise locations of the jet slit and the radii of the trailing edge were varied in several ways and the changes in the lift characteristics have been observed at the various angles of attack, particularly focusing on the usefulness of the Coanda effect upon delaying the stall or increase in the circulation. Making the most use of the results so attained, full spade rudder of a VLCC has been reformed to realize the Coanda effect. A series of model experiments and numerical simulations are performed to confirm the effectiveness of the Coanda effect in improving the performance of the modified rudder. It is found that considerable enhancement in the lift performance of the rudder is plausible at any rudder angle if an optimum jet momentum is provided.
Fluid-Structure Interaction Analysis on the Deformation of Simplified Yacht Sails
Bak, Sera ; Yoo, Jaehoon ; Song, Chang Yong ;
Journal of the Society of Naval Architects of Korea, volume 50, issue 1, 2013, Pages 33~40
DOI : 10.3744/SNAK.2013.50.1.33
Since most of yacht sails are made of thin fabric, they form cambered sail shape that can efficiently generate lift power by aerodynamic interaction and by external force delivered from supporting structures such as mast and boom. When the incident flow and external force alter in terms of volume or condition, the shape of sail also change. This deformation in shape has impact on the peripheral flow and aerodynamic interaction of the sail, and thus it is related to the deformation of the sail in shape again. Therefore, the precise optimization of aerodynamic performance of sail requires fluid-structure interaction (FSI) analysis. In this study, the simplified sail without camber was under experiment for one-way FSI that uses the result of flow analysis to the structural analysis as load condition in an attempt to fluid-structure interaction phenomenon. To confirm the validity of the analytical methods and the reliability of numerical computation, the difference in deformation by the number of finite element was compared. This study reproduced the boundary conditions that sail could have by rigs such as mast and boom and looked into the deformation of sail. Sail has non-linear deformation such as wrinkles because it is made of a thin fabric material. Thus non-linear structural analysis was conducted and the results were compared with those of analysis on elastic material.
Notch Strain Analysis of Cruciform Welded Joint using Nonlinear Kinematic Hardening Model
Kim, Yooil ; Kim, Kyung-Su ;
Journal of the Society of Naval Architects of Korea, volume 50, issue 1, 2013, Pages 41~48
DOI : 10.3744/SNAK.2013.50.1.41
Several fatigue damages have recently been reported which cannot be resolved in the context of the existing fatigue design procedure, and they are suspected to be the cracks induced by the low cycle fatigue mechanism. To tackle the problem, a series of material tests together with fatigue tests have been carried out, and elasto-plastic notch strain analysis using nonlinear kinematic hardening model has been performed. The cyclic stress-strain curves are obtained and the nonlinear kinematic hardening model was calibrated based on the obtained material data. Also, the fatigue test with non-load-carrying cruciform fillet welded joint has been performed in low cycle fatigue regime. Then, the notch strain analyses have been carried out to find the precise elasto-plastic behavior of the material at the notch root of the cruciform joint. The variation of the material property from the base metal via HAZ up to the weld metal was taken into account using spatial variation of the material property. Then the detail elasto-plastic behavior of the welded joint subjected to the repeated cyclic loading has been investigated further through the comparison with the prediction with Neuber`s rule. The calibration of the nonlinear kinematic hardening model and nonlinear notch strain analyses have been performed using the commercial FE program ABAQUS.
Comparative Study on Added Resistance for Different Hull Forms by using Weakly-Nonlinear Seakeeping Formulations
Seo, Min-Guk ; Kim, Kyong-Hwan ; Park, Dong-Min ; Kim, Yonghwan ;
Journal of the Society of Naval Architects of Korea, volume 50, issue 1, 2013, Pages 49~58
DOI : 10.3744/SNAK.2013.50.1.49
Recently, the design of commercial ships with less green-house gas is one of great interests in naval architecture fields. Ship designers are asked to find optimum hull forms with minimum resistance in ocean waves. The accurate computation of added resistance, therefore, is getting more important for the prediction of power increase in random ocean waves. This study focuses on the numerical computation of added resistance on ships with Ax-bow shapes which are designed to reduce added resistance. To this end, the time-domain Rankine panel methods based on weakly-nonlinear and weak-scatterer approaches are applied, which can reflect the influence of above-still-water bow shape. As computational models, KCS and KVLCC2 hull forms are considered. Each ship is combined with the three types of Ax-bow shape, and computational results are compared each other.
Development of Automated Algorithm for Compartment Arrangement of Oil Tanker
Song, Ha-Cheol ; Na, Seung-Su ; Jo, Du-Yeon ; Shim, Cheon-Sik ; Lee, Gang-Hyeon ; Jeong, Sol ; Heo, Joo-Ho ; Jeong, Tae-Seok ; Lee, Chul-Ho ; Jo, Young-Chun ; Kim, Dong-Chun ;
Journal of the Society of Naval Architects of Korea, volume 50, issue 1, 2013, Pages 59~68
DOI : 10.3744/SNAK.2013.50.1.59
Nowadays, optimum structural design techniques based on CSR have been developed and applied to the preliminary design stage focused on minimum weight and minimum construction cost of ship structure. Optimum structural design algorithm developed before could minimize weight and cost on fixed compartment arrangement. However, to develop more efficient design technique, a designer needs to combine optimized compartment arrangement with optimized ship structural design because compartment arrangement has a large effect on structural design according to the change of still water bending moment as a consequence of compartment arrangement change. In this study, automated algorithm for compartment arrangement of an oil tanker is developed to apply preliminary structural design. The usefulness of developed algorithm is verified with Aframax oil tanker constructed by STX shipbuilding Co.Ltd..