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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 43, Issue 6 - Dec 2006
Volume 43, Issue 5 - Oct 2006
Volume 43, Issue 4 - Aug 2006
Volume 43, Issue 3 - Jun 2006
Volume 43, Issue 2 - Apr 2006
Volume 43, Issue 1 - Feb 2006
Selecting the target year
A Review and Analysis on the Interim Guidelines for Alternative Assessment of the Weather Criterion by Drifting and Motion Test in Waves
Yoon, Hyeon-Kyu ; Kim, Sun-Young ; Kim, Jin-Ha ; Kim, Young-Shik ; Hong, Sa-Young ;
Journal of the Society of Naval Architects of Korea, volume 43, issue 5, 2006, Pages 529~537
DOI : 10.3744/SNAK.2006.43.5.529
International Maritime Organization (IMO) is planning to include the Alternative Assessment of the Weather Criterion in the new Intact Stability (IS) Code to be revised. In this study, the procedure of the model test in the Interim Guidelines was reviewed by carrying out the model test and analyzing the test results. For this purpose, RO/RO passenger ship whose ratios of breadth to draft and the height of weight to draft were above 3.5 and above 0.6 respectively was selected as a test ship. Drifting test and motion test in regular waves were performed to estimate the hydrodynamic heeling lever and roll-back angle. Motion tests in waves were carried out in the three wave steepness conditions to measure roll-back angle and examine the feasibility of so called, the Three-step method. Using the test data, satisfaction of the Weather Criterion was assessed for the test ship by using the alternative method and compared with the current method.
Numerical Simulation of a Viscous Flow Field Around a Deforming Foil Using the Hybrid Cartesian/Immersed Boundary Method
Shin, Sang-Mook ; Kim, Hyoung-Tae ;
Journal of the Society of Naval Architects of Korea, volume 43, issue 5, 2006, Pages 538~549
DOI : 10.3744/SNAK.2006.43.5.538
A code is developed to simulate a viscous flow field around a deformable body using the hybrid Cartesian/immersed boundary method. In this method, the immersed boundary(IB) nodes are defined near the body boundary then velocities at the IB nodes are reconstructed based on the interpolation along the normal direction to the body surface. A new method is suggested to define the IB nodes so that a closed fluid domain is guaranteed by a set of IB nodes and the method is applicable to a zero-thickness body such as a sail. To validate the developed code, the vorticity fields are compared with other recent calculations where a cylinder orbits and moves into its own wake. It is shown the code can handle a sharp trailing edge at Reynolds number of
under moderate requirements on girds. Finally the developed code is applied to simulate the vortex shedding behind a deforming foil with flapping tail like a fish. It is shown that the acceleration of fluids near the flapping tail contributes to the generation of the thrust for propulsion.
Hull Form Optimization by Modification Function of Bell-shaped Distribution
Choi, Hee-Jong ; Kim, Hee-Jung ; Chun, Ho-Hwan ; Jung, Kwang-Hyo ;
Journal of the Society of Naval Architects of Korea, volume 43, issue 5, 2006, Pages 550~559
DOI : 10.3744/SNAK.2006.43.5.550
A design procedure for a ship with minimum total resistance was developed using a numerical optimization method called SQP(Sequential Quadratic Programming) and a CFD technique based on the Rankine source panel method with the nonlinear free surface boundary conditions. During the whole optimization process the geometry of the hull shape was represented based on the NURBS(Non-uniform rational B-spline) technique and the modification of the hull shape was controlled using the Bell-shaped distribution function to keep the fairness of the hull shape before and after the hull modification. The numerical analysis was carried out using 4000TEU container ship in the towing tank facility installed in the Pusan national university to know the validity of the developed algorithm for this study. As the results of the numerical analysis it proved that the resistance of the optimized hull is conspicuously reduced in comparison with the original hull in a wave-making resistance point of view.
Nonlinear Motion Analysis of FPSO and Shuttle Tanker in a Tandem Configuration
Lim, Choon-Gyu ; Lee, Ho-Young ; Shin, Hyung-Young ;
Journal of the Society of Naval Architects of Korea, volume 43, issue 5, 2006, Pages 560~567
DOI : 10.3744/SNAK.2006.43.5.560
FPSO and shuttle tanker are connected to each other by a mooring hawser and a loading hose through which cargo oil is off-loaded. Even in mild sea-state. environmental loads can cause unstable large drift motions between two vessels in tandem off-loading operations, which may result in collision incidents. Accordingly. the analysis on the relative motion between two vessels due to the environmental loads should be investigated in initial design stage. In this study, the low speed maneuvering equation is employed to simulate nonlinear motions of FPSO and shuttle tanker. Low frequency wave drift forces including hydrodynamic interactions between two vessels are evaluated by near field approaches. Current loads are determined by mathematical model of MMG and wind loads are calculated by employing the wind spectrum according to the guidelines of API-RP2A. Mooring forces produced by turret mooring lines and a flexible hawser are modeled quasi-statically by catenary equations. The effect of environmental loads that affect nonlinear motion is investigated through variation in their magnitudes and the nonlinear motions between FPSO and shuttle tanker are simulated under wave, current and wind in time domain.
Numerical Calculation and Validation for Rudder Cavitation of a Large Container Ship
Kim, Gun-Do ; Moon, Il-Sung ; Kim, Kyoung-Youl ; Van, Suk-Ho ; Lee, Chang-Sup ;
Journal of the Society of Naval Architects of Korea, volume 43, issue 5, 2006, Pages 568~577
DOI : 10.3744/SNAK.2006.43.5.568
With the increase of ship size and speed, the loading on the propeller is increasing, which in turn increases the rotational speed in the propeller slipstream. The rudder placed in the propeller slip stream is therefore subject to severe cavitation with the increased angle of attack due to the increased rotational induction speed of the propeller. In the present paper the surface panel method, which has been proved useful in predicting the sheet cavitation on the propeller blade, is applied to solve the cavity boundary value problem on the rudder. The problem is then solved numerically by discretizing the rudder and cavity surface elements of the quadrilateral panels with constant strengths of sources and dipoles. The strengths of the singularities are determined satisfying the boundary conditions on the rudder and cavity surfaces. The extent of the cavity, which is unknown a priori, is determined by iterative procedure. Series of numerical experiments are performed increasing the degree of complexity of the rudder geometry and oncoming flows from the simple hydrofoil case to the real rudder in the circumferentially averaged propeller slipstream. Numerical results are presented with experimental results.
An Experimental Research on Gap Cavitation Erosion of Semi-spade Rudder
Kim, Sung-Pyo ; Park, Jae-Jun ; Kim, Yong-Soo ; Jang, Young-Hun ; Choi, Young-Bok ; Paik, Bu-Geun ;
Journal of the Society of Naval Architects of Korea, volume 43, issue 5, 2006, Pages 578~585
DOI : 10.3744/SNAK.2006.43.5.578
Cavitation related erosion damages on semi-spade rudder generally occur at around leading edge of lower-face and behind gap of lower pintle. To get the idea of gap entrance profile for the latter case, a series of tests with large models has been carried out at MOERI. In the tests, the flow pattern around lower pintle have been investigated and visualized by high speed camera. Additionally, cavitation inception tests and pressure measurements have also been conducted for better comparison. As a result a new model (F rudder) has been developed. The new model turned out to have stable pressure distribution along the surface and so the cavitation inception speeds within
of rudder angle were delayed approx. 4 knots in average.
Application of the Internal Degree of Freedom to 3D FDLB Model and Simulations of Aero-Acoustic
Kang, Ho-Keun ; Ahn, Soo-Whan ; Kim, Jeong-Whan ;
Journal of the Society of Naval Architects of Korea, volume 43, issue 5, 2006, Pages 586~596
DOI : 10.3744/SNAK.2006.43.5.586
A 3-dimensional FDLB model with additional internal degree of freedom is applied for diatomic gases such as air, in which an additional distribution function is introduced. Direct simulations of aero-acoustic by using the applied model and scheme are presented. Speed of sound is correctly recovered. As typical examples, the Aeolian tone emitted by a circular column is successfully simulated even very low Mach number flow. Acoustic pressure fluctuations with the same frequency of the Karman vortex street compared with the pressure fluctuation around a circular column is captured. Full three-dimensional acoustic wave past a compact block like pentagon, furthermore, is also emitted in y direction as dipole like sound.
Estimation of Distributed and Joint-excited Input Power for Power Flow Analysis
Kim, Dong-Jin ; Hong, Suk-Yoon ;
Journal of the Society of Naval Architects of Korea, volume 43, issue 5, 2006, Pages 597~603
DOI : 10.3744/SNAK.2006.43.5.597
The estimations of distributed and joint-excited input power for Power Flow Analysis are accomplished in this paper. Using Fourier transform, the displacements of infinite structures are derived, and the input power of distributed excitation can be estimated. The obtained results compare the real input power with the estimation of input power. When the exciting force acts on the joint of coupled structures, it is estimating the power that is transferred to each structure. Appling this input power, the results of energy density and intensity of Power Flow Analysis can be compared with the classical solutions.
Ultimate Strength Assessment of Bollard and Its Foundation Considering Production Costs
Oh, Chang-Min ; Choung, Joon-Mo ; Cho, Sang-Rai ;
Journal of the Society of Naval Architects of Korea, volume 43, issue 5, 2006, Pages 604~610
DOI : 10.3744/SNAK.2006.43.5.604
Common structural rules of JBP(Joint Bulker Project) and JTP(Joint Tanker Project), which will come into effect in 2006, invoke the necessity of the ultimate limit state(ULS) design for ship structures. Even though the many applications of ULS analysis have been performed for ship structures, there have few studies carried out for deck machineries and their supporting structures. Recently four major Korean shipbuilders(DSME, HHI, HHIC, SHI) jointly developed and proposed a new design standards for mooring fittings and also proposed the SWL (Safety Working Load) obtained based on the first yield criterion. In this study, various ultimate strength analyses were performed for bollards and their foundation structures whose yield strengths were quantified by the research consortium. Prior to performing the ultimate strength analyses, the numerical calculation method was substantiated with the test results provided in the joint work report. Based upon the results of this study, it can be concluded that the reinforcements to increase the yield strength are not always resulted in the enhancement of the ultimate strength. Furthermore, the additional production costs for the reinforcements can not be rewarded by the ultimate strength. Therefore, another alternative arrangements should be developed in the view point of ultimate strength.
3D Digital Mockup Application of Cryogenic Butterfly Valve, LNG Carrier
Lee, Dong-Hun ; Kim, Duck-Eun ; Kim, Soo-Young ; Park, Gy-Young ;
Journal of the Society of Naval Architects of Korea, volume 43, issue 5, 2006, Pages 611~618
DOI : 10.3744/SNAK.2006.43.5.611
Recently, cryogenic butterfly valves for LNG carriers are actively developed by ship equipment companies. The dual core structure unlike usual butterfly valve has both translation and gyration motions of the disk of the valve assembly. Especially, the ship equipment companies can not have overcome 2D design method; in addition, even though 2 years of development has passed, the drawing cannot be secured. In this research, for the cryogenic butterfly valves and the product design, 3D design method was introduced and DMU(Digital Mockup) was applied to complement the problems in 2D design and investigate application possibility of 3D design method.
Network-based Simulation System Framework for the Safety Assessment of Ship and Visualization Method
Lee, Kyung-Ho ; Kim, Hwa-Seop ; Oh, June ; Park, Jong-Hoon ;
Journal of the Society of Naval Architects of Korea, volume 43, issue 5, 2006, Pages 619~629
DOI : 10.3744/SNAK.2006.43.5.619
The safety assessment of the structure related to people has become the most important part in the process of the design. Especially, in the case of a ship, as regulations about the safety of passengers and the pollution in the ocean are strictly reinforcing, the safety assessment has become the most important part in the process of the design. In this paper, we suggested network-based simulation system framework using HLA (High Level Architecture) among many kind of simulations to assess the safety of the ship. In addition, the visualization method which is composed of graphic user interface for ship modeling and the visualization of ship motion is presented.