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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 45, Issue 6 - Dec 2008
Volume 45, Issue 5 - Oct 2008
Volume 45, Issue 4 - Aug 2008
Volume 45, Issue 3 - Jun 2008
Volume 45, Issue 2 - Apr 2008
Volume 45, Issue 1 - Feb 2008
Selecting the target year
Influence of Jet Nozzle Arrangement on the Performance of a Coanda Foil
Seo, Dae-Won ; Kim, Joung-Hyun ; Kim, Hyo-Chul ; Lee, Seung-Hee ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 569~578
DOI : 10.3744/SNAK.2008.45.6.569
The Coanda effects demonstrate that a jet stream applied tangential to a curved surface can generate lift force by increasing the circulation. Many experimental and numerical studies have been performed on the Coanda effect and it is found to be useful in various fields of aerodynamics. The Coanda effect may have practical application to marine hydrodynamics since various control surfaces are being used to control behaviors of ships and offshore structures. In the present study, numerical computations are performed to find the applicability of the Coanda effect to the marine control surfaces. For the purpose, changes in flow characteristics around a flapped foil due to the Coanda effect have been simulated by RANS equations discretized with a cell-centered finite volume method (FVM). In the process, special attention has been given to the influence of jet nozzle arrangement on the lift characteristics of the Coanda foil. It is found that the shape as well as the location of the jet intake and jet exit affects the lift performance of the foil significantly.
A Study On the Position Control System of the Small ROV Using Sonar Sensors
Choi, Dong-Hyun ; Um, Geun-Nam ; Kim, Sang-Hyun ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 579~589
DOI : 10.3744/SNAK.2008.45.6.579
In the past few years, there are many studies and researches of the underwater vehicles which are carried out its mission using sonar sensors. MSCL(Marine System Control Lab.) at Inha University developed test-bed small ROV, ISRO. ISRO is an open-frame type and has 4 thrusters. ISRO can control 4 motions i.e surge, sway, yaw and heave with sonar sensors. ISRO is developed for inspection of ship hull, marine structure, plant of lake or river and so on. When ROV ISRO inspects something, it is necessary to control the position of ROV ISRO's for the movement and anti-collision with structures in the underwater. In this paper, we deal with the development of a small ROV and verification of the position control system via simulation and experiment using sonar sensors.
Hull Form Optimization using Parametric Modification Functions and Global Optimization
Kim, Hee-Jung ; Chun, Ho-Hwan ; An, Nam-Hyun ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 590~600
DOI : 10.3744/SNAK.2008.45.6.590
This paper concerns the development of a designer friendly hull form parameterization and its coupling with advanced global optimization algorithms. As optimization algorithms, we choose the Partial Swarm Optimization(PSO) recently introduced to solve global optimization problems. Most general-purpose optimization softwares used in industrial applications use gradient-based algorithms, mainly due to their convergence properties and computational efficiency when a relatively few number of variables are considered. However, local optimizers have difficulties with local minima and non-connected feasible regions. Because of the increase of computer power and of the development of efficient Global Optimization (GO) methods, in recent years nongradient-based algorithms have attracted much attention. Furthermore, GO methods provide several advantages over local approaches. In the paper, the derivative-based SQP and the GO approach PSO are compared with their relative performances in solving some typical ship design optimization problem focusing on their effectiveness and efficiency.
Surface Modeling of Forebody's Hull Form Using Form Parameters and Fair-Skinning
Kim, Hyun-Cheol ; HwangBo, Seung-Myun ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 601~610
DOI : 10.3744/SNAK.2008.45.6.601
This paper deals with a new geometrical surface modeling method of forebody's hull form which is fully defined by form parameters. The complex hull form in the forebody can be modeled by the combination of three parts: bare hull, bulbous bow and blending part which connects a bare hull and a bulbous bow. All these subdomain parts are characterized by each own form parameters and constructed with simple surface model. For this, we need only 2-dimensional hull form data and then the form parameters are calculated automatically from these data. Finally, the smooth hull form surfaces are generated by parametric design and fair-skinning. In the practical point of view, we show that this new method can be useful and efficient modeling tool by applying to the hull form surface modeling of Panamax container's forebody.
Model Test and Numerical Simulation of the Behaviour of Dock-Gate in Waves
Shin, Hyun-Kyoung ; Kim, Min-Sung ; Noh, Cheol-Min ; Yang, Seung-Ho ; Cho, Jin-Woog ; Kim, Joung-Wook ; Kim, Sam-Ryong ; Yang, Young-Chul ; Kim, Bong-Min ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 611~619
DOI : 10.3744/SNAK.2008.45.6.611
In most shipyards Floating Dock-gate System is adapted for dry docks. For the safe launching of ships in dry docks, smooth operation of dock-gate must be guaranteed. So it is very important to grasp its behavior in waves for securing the high productivity and the safety of workers. Its seakeeping ability was estimated numerically at the floating conditions and the free roll decay and the seakeeping model tests of dock-gate was carried out with bilge-keels of 3 different widths which have a scale of 1 to 20. More than 20% decrease of roll motion was observed in irregular beam seas by applying a bilge-keel system to the dock-gate that is long and narrow.
Visualization of Unstable Vortical Structure in a Propeller Wake Affected by Simulated Hull Wake
Kim, Kyung-Youl ; Paik, Bu-Geun ; Ahn, Jong-Woo ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 620~630
DOI : 10.3744/SNAK.2008.45.6.620
The characteristics of complicated propeller wake influenced by hull wake are investigated by using a two-frame PIV (Particle Image Velocimetry) technique. As the propeller is significantly affected by the hull wake in a real marine vessel, the measurements of propeller wake under the hull wake would be certainly necessary for more reliable validation and the prediction of numerical simulation with wake modeling. Velocity field measurements have been conducted in a medium-size cavitation tunnel with a hull wake. Generally, the hull wake generated by the boundary layer of ship's hull produces the different loading distribution on the propeller blade in both upper and lower propeller planes. The difference of the propeller wake behaviors caused by the hull wake is discussed in terms of axial velocity, vorticity and turbulence kinetic energy distribution in the present study.
Numerical Analysis of High-Reynolds-Number Flow around Axisymmetric Body
Choi, Jung-Kyu ; Kim, Hyoung-Tae ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 631~636
DOI : 10.3744/SNAK.2008.45.6.631
In this paper, numerical analysis based on the RANS equation and the Realizable
turbulence model is carried out for flows around an axisymmetric body at three Reynolds numbers(
) and the numerical results are compared with experiments data. Computed velocity distributions agree well with experiments as the Reynolds number increases. Pressure distributions agree well with the results of the potential flow except the tail region but differ from experiments for the parallel middle body as well as tail region. Pressure gradients show a good agreement with those of potential flow and experiment except the tail region. Friction coefficients show that the numerical results generally are lower than the experimental results estimated from the measured velocity. The difference of friction coefficients between the calculation and the experiment increases with growing of a boundary layer.
A Study on Development and Verification of Prediction Formula for Realization of Standard Process for Hull Block Coating Method
Kim, Dong-Kyun ; Lee, Dong-Hoon ; Kim, Ho-Kyeong ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 637~645
DOI : 10.3744/SNAK.2008.45.6.637
It is very hard to control the quality of coating work in shipbuilding process, because it is highly affected by several parameters such as space between object and nozzle tip, spray velocity, pressure, tip size, etc.. Even so a coating work in shipbuilding is done by workers' experience and skill as yet. It causes not only an excessive use of paints but also a decrease of productivity. In order to solve this problem, we developed a formula that predicts the film thickness and determined the proper coating pattern. Also we had done a series of experiments to verify the results of this study.
Optimal Block Transportation Scheduling Considering the Minimization of the Travel Distance without Overload of a Transporter
Yim, Sun-Bin ; Roh, Myung-Il ; Cha, Ju-Hwan ; Lee, Kyu-Yeul ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 646~655
DOI : 10.3744/SNAK.2008.45.6.646
A main issue about production management of shipyards is to efficiently manage the work in process and logistics. However, so far the management of a transporter for moving building blocks has not been efficiently performed. To solve the issues, optimal block transporting scheduling system is developed for minimizing of the travel distance without overload of a transporter. To implement the developed system, a hybrid optimization algorithm for an optimal block transportation scheduling is proposed by combining the genetic algorithm and the ant algorithm. Finally, to evaluate the applicability of the developed system, it is applied to a block transportation scheduling problem of shipyards. The result shows that the developed system can generate the optimal block transportation scheduling of a transporter which minimizes the travel distance without overload of the transporter.
The Normal Diving Simulation of the Underwater Vehicle Using the Standard Model Architecture for the Combined Simulation of Discrete Event System and Discrete Time System
Son, Myeong-Jo ; Lee, Hyun-Jin ; Ham, Seung-Ho ; Lee, Hyo-Kwang ; Kim, Tae-Wan ; Lee, Kyu-Yeul ; Han, Soon-Hung ; Nah, Young-In ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 656~668
DOI : 10.3744/SNAK.2008.45.6.656
When it comes to design and acquire underwater vehicles such as a submarine and a torpedo according to the process of SBA(Simulation Based Acquisition)/SBD(Simulation Based Design), it is necessary to predict the performance of interest precisely and to perform the test over and over again using the M&S(Modeling and Simulation) of the engineering and the engagement level. In this paper, we research the DEVS(Discrete Event System Specification) and DTSS(Discrete Time System Specification) formalism based standard model architecture for the underwater vehicle which can support both the heterogeneous level of the M&S(Engineering/Engagement) and the different system of the M&S(Discrete Event System and Discrete Time System). To validate this standard modeling architecture, we apply it to the submarine normal diving simulation.
A Study of Crack Propagation and Fatigue Life Prediction on Welded Joints of Ship Structure(I)
Kim, Kyung-Su ; Ito, Hisashi ; Seo, Yong-Seok ; Jang, Beam-Sean ; Kim, Beam-Il ; Kwan, Young-Bin ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 669~678
DOI : 10.3744/SNAK.2008.45.6.669
The fatigue life of ship structure under cyclic loading condition is made up of initiation and propagation stages. In this study, crack growth test is carried out on large scale structure test specimens and fracture mechanical analysis is performed. The fatigue lives measured from fatigue tests are compared with DNV, Matsuoka and BS 5400 S-N curve. And to predict the crack initiation life, S-N curve, corresponding to crack length 20mm at welded joint, is developed based on hot spot stress range. Also crack propagation life is calculated using crack growth equation. Consequently, computed crack propagation life is compared with experiment results.
A Study of Crack Propagation and Fatigue Life Prediction on Welded Joints of Ship Structure (II)
Kim, Kyung-Su ; Shim, Chun-Sik ; Kwon, Young-Bin ; Ko, Hee-Seung ; Ki, Hyeok-Geun ; Viswanathan, K.K. ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 679~687
DOI : 10.3744/SNAK.2008.45.6.679
The fatigue life of ship structure under cyclic loading condition is made up of crack initiation and propagation stages. For a welding member in ship structure, the fatigue crack propagation life is more important than the fatigue crack initiation life. To calculate precisely the fatigue crack propagation life at the critical welding location, the knowledge of the residual stress sensitivity on the fatigue strength is necessary. In this study, thermo elastic-plastic analysis was conducted in order to examine the effect of residual stress on the fatigue crack propagation life. Also the fatigue crack propagation lives considering residual stress were calculated using fatigue crack growth code, AFGROW, on the basis of fracture mechanics. AFGROW is widely used for fatigue crack growth predictions under constant and variable amplitude loading. The reliability of AFGROW on the fatigue of ship structure was confirmed by the comparison of the estimated results with the fatigue propagation test results.
Reduction of the Vibration Transmissibility for the Sea-Water Conveying Pipe in a Ship According to its Mount Shape
Han, Hyung-Suk ; Jeong, Weui-Bong ; Cha, Young-Ju ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 688~694
DOI : 10.3744/SNAK.2008.45.6.688
The reduction of the structure-borne noise is very important in order to reduce the noise of a ship. The noise at the high frequency range usually comes from the fluid flowing. The noise from the sea-water conveying pipe is one of the main source on these high frequency range. Therefore, the transmissibility variations are evaluated according to the shape of the rubber mount. The evaluations are performed with the frequency response function numerically and experimentally.
Near-field Sonar Cross Section Analysis of Underwater Target Using Spherical Projection Method
Kim, Kook-Hyun ; Cho, Dae-Seung ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 695~702
DOI : 10.3744/SNAK.2008.45.6.695
In this paper, a new numerical method is proposed to analyze near-field sonar cross section of acoustically large-sized underwater targets such as submarines. A near-field problem is converted to a far-field problem using a spherical projection method with respect to the objective target. Then, sonar cross section is calculated with a physical optics well established in far-field acoustic wave scattering problems. The analysis results of a square flat plate compared with those obtained by other method show the accuracy of the proposed method. Moreover, it is noted that the sonar cross section is varied with respect to the targeting point as well as the range. Finally, numerical analysis results of real-like underwater target such as a submarine pressure hull are discussed.
Simulation of Plate Deformation due to Triangle Heating Using Inherent Strain Method
Jang, Chang-Doo ; Ko, Dae-Eun ; Ha, Yun-Sok ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 703~709
DOI : 10.3744/SNAK.2008.45.6.703
In the shipyard, line heating and triangle heating are two major processes for forming curved plates in various shapes. While there have been many studies on line heating, triangle heating has been rarely studied due to its complicated heating process with irregular multi-heating paths and highly concentrated heat input. As the triangle heating process is one of the most labor-consuming jobs in shipyards, it is essential to study the automation as well as improvement of triangle heating process in order to increase hull forming productivity. In this study, a pioneering attempt to simulate triangle heating was made. A circular disk-spring model was proposed for elasto-plastic analysis procedure of triangle heating and the inherent strain method was also used to analyze the deformation of plates. Simulation results were compared with those of experiments and showed good agreement. It is shown that the present approach including analysis model used in this study is effective to simulate the triangle heating for plate forming process in shipbuilding.
On the Docking Analysis of Global Ship Structure Using Simplified Grillage Model
Kim, Sung-Chan ; Ryu, Cheol-Ho ; Lee, Jang-Hyun ; Lee, Kyung-Seok ; Baek, Ki-Dae ; Sohn, Sang-Yong ; Choi, Joong-Hyo ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 710~718
DOI : 10.3744/SNAK.2008.45.6.710
This paper presents a simple and fast approach to plan the arrangement of supports and to do a ship docking analysis. The unpredicted structural damages often happen from a docking works as the size of ships are getting larger and larger. In docking a ship, excessive reaction forces from supports are primary causes of the structural damage. The grillage analysis method is employed to simply calculate only the reaction forces at supports. The grillage modeling strategies are proposed to improve the accuracy. In this paper, the results obtained by the proposed approach are compared with those of the current whole-ship FEA for typical types of ships. Comparison shows that the results from the present grillage approaches are reasonably in a good agreement with the 3-D full F.E one. Finally, an integrated program developed for the ship docking analysis is described.
A Study on Noise and Vibration Reduction Measurements of a Floating Floor Structure by means of a Ship Cabin Mock-up
Kim, Hyun-Sil ; Kim, Jae-Seung ; Kang, Hyun-Ju ; Kim, Bong-Ki ; Kim, Sang-Ryul ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 719~725
DOI : 10.3744/SNAK.2008.45.6.719
In this paper, noise and vibration reduction for floating-floored ship cabin is studied. A mock-up is built by using 6 mm steel plate, and two identical cabins are made for simulation of ship cabins. When a speaker is used as a sound and vibration sources, it is shown that floating floor is more effective in isolating sound than bare deck by 2-5 dB. It is also shown that structure-borne noise of the bare deck is greater than that of floating-floored deck by 3-10 dB. For tapping machine excitation, it is found that the effect of floating floor in airborne noise and structure-borne noise reduction reaches up to 40-50 dB for high frequency ranges.
Wet Drop Impact Response Analysis of CCS in Membrane Type LNG Carriers -I : Development of Numerical Simulation Analysis Technique through Validation-
Lee, Sang-Gab ; Hwang, Jeong-Oh ; Kim, Wha-Soo ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 726~734
DOI : 10.3744/SNAK.2008.45.6.726
While the structural safety assessment of Cargo Containment System(CCS) in membrane type LNG carriers has to be carried out in consideration of sloshing impact pressure, it is very difficult to figure out its dynamic response behaviors due to its very complex structural arrangements/materials and complicated phenomena of sloshing impact loading. For the development of its original technique, it is necessary to understand the characteristics of dynamic response behavior of CCS structure under sloshing impact pressure. In this study, for the exact understanding of dynamic response behavior of CCS structure in membrane Mark III type LNG carriers under sloshing impact pressure, its wet drop impact response analyses were carried out by using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code, and were also validated through a series of wet drop experiments for the enhancement of more accurate shock response analysis technique. It might be thought that the structural response behaviors of impact response analysis, such as impact pressure impulses and resulted strain time histories, generally showed very good agreement with experimental ones with very appropriate use of FSI analysis technique of LS-DYNA code, finite element modeling and material properties of CCS structure, finite element modeling and equation of state(EOS) of fluid domain.
Wet Drop Impact Response Analysis of CCS in Membrane Type LNG Carriers -II : Consideration of Effects on Impact Response Behaviors-
Lee, Sang-Gab ; Hwang, Jeong-Oh ; Kim, Wha-Soo ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 6, 2008, Pages 735~749
DOI : 10.3744/SNAK.2008.45.6.735
For the development of the original technique of structural safety assessment of Cargo Containment System(CCS) in membrane type LNG carriers, it is necessary to understand the characteristics of dynamic response behavior of CCS structure under sloshing impact pressure. In the previous study, the wet drop impact response analyses of CCS structure in membrane Mark III type LNG carriers were carried out by using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code, and were also validated through a series of wet drop experiments for the enhancement of more accurate shock response analysis technique. In this study, the characteristics of structural shock response behaviors of CCS structure were sufficiently figured out by careful examinations of the effects of specimen weight, drop height, incident angle, corrugation and stiffness of inner hull on its shock response behaviors. The shock response analysis of upward shooting fluid to inner hull was performed, and the reason of faster strain response than shock pressure one was also figured out.