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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
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Numerical Simulation for Fluid Impact Loads by Flat Plate with Incident Angles
Lee, Byung-Hyuk ; Jung, Sung-Jun ; Ryu, Min-Cheol ; Kim, Yong-Su ; Park, Jong-Chun ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 1~9
DOI : 10.3744/SNAK.2008.45.1.1
The free-surface motions interacting with structures are investigated numerically using the Moving Particle Semi-implicit (MPS) method proposed by Koshizuka et al. (1996) for solving incompressible flow. In the method, Lagrangian moving particles are used instead of Eulerian approach using grid system. Therefore the terms of time derivatives in Navier-Stokes equation can be directly calculated without any numerical diffusion or instabilities due to the fully Lagrangian treatment of fluid particles and topological failure never occur. The MPS method is applied to the numerical study on the fluid impact loads for wet-drop tests in a LNG tank, and the results are compared with experimental ones.
Meshless Advection using Flow Directional Local Grid
Jung, Sung-Jun ; Lee, Byung-Hyuk ; Park, Jong-Chun ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 10~17
DOI : 10.3744/SNAK.2008.45.1.10
In this paper an accurate and stable gridless method that can be applied to multi-dimensional convection problems is developed on a flow directional local grid. A two dimensional pure convection problem is calculated and more accurate and stable solution is obtained compared with other schemes in grid method. The tested numerical schemes include 1st-order upwind scheme, 2nd-order Leith scheme, 3rd-order MUSCL, and QUICK scheme. It is seen that more accurate results are expected when the schemes combined with a MMT control limiter.
On the Influence of End Plates upon the Tip Vortex Cavitation Characteristics of a Fin Stabilizer
Seo, Dae-Won ; Kim, Joung-Hyun ; Lee, Seung-Hee ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 18~28
DOI : 10.3744/SNAK.2008.45.1.18
Fins are widely used for roll stabilization of passenger ferries and high performance naval ships, among others. In the present study, numerical simulations are performed to investigate the influence of end-plates upon the cavitation characteristics of a stabilizer fin for various angles of attack and speeds and the results are verified through a series of model experiments. It is found that a considerable retardation in tip vortex cavitation can be achieved with attachment of end-plates at the tip of the stabilizer fin. The results can be utilized for the design of stabilizer fins as well as the development of high performance control devices for ships.
Unsteady RANS Analysis of the Hydrodynamic Response for a Ship with Forward Speed in Regular Wave
Park, Il-Ryong ; Kim, Kwang-Soo ; Kim, Jin ; Van, Suak-Ho ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 29~41
DOI : 10.3744/SNAK.2008.45.1.29
The present paper provides a CFD analysis of diffraction problem for a ship with forward speed using an unsteady RANS simulation method, a WAVIS code. The WAVIS viscous solver adopting a finite volume method has second order accuracy in time and field discretizaions for the RANS equations. A two phase level-set method and a realizable
turbulence model are adopted to compute the free surface and to meet the turbulence closure, respectively. To validate the capability of the present numerical methods for the simulation of an unsteady progressive regular wave, computations are performed for three grid sets with refinement ratio of
. The main simulation is performed for a DTMB5512 model with a forward speed in a regular head sea condition. Validation of the present numerical method is carried out by comparing the present CFD results with available unsteady experimental data published in the 2005 Tokyo CFD Workshop: resistance, heave force, pitch moment, unsteady free surface elevations and velocity fields.
Measurement of Honeycomb Turbulence in a Cavitation Tunnel Using Particle Image Velocimetry Method
Ryu, Min-Cheol ; Oh, Jung-Geun ; Kim, Yoo-Chul ; Koh, Won-Gyu ; Lee, Youn-Mo ; Suh, Jung-Chun ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 42~53
DOI : 10.3744/SNAK.2008.45.1.42
The two dimensional PIV (particle image velocimetry) measurement technique is applied to water flow in a narrow cavitation tunnel. The nearly homogeneous and isotropic turbulent flows are generated by the honeycomb installed in the tunnel and visualized with a PIV technique. The velocities in the measurement plane at the tunnel centerline 184cm downward from the honeycomb were measured and calculated by an image correlation technique. The turbulent properties are evaluated and each term in the turbulent kinetic energy equation is calculated for the conditions with different internal pressures. Lowering the internal pressure gives an effect on the turbulent flow due to growing bubbles which are resolved in the water. The turbulent kinetic energy in the measurement plane is decayed much slower than those of other research results carried out with wind tunnels. With decreasing the tunnel internal pressures the turbulent intensities are increased about 1.5 times and the anisotropic tendency is also increased.
Variable Free Surface Panel Method for Potential Flow Analysis around a Ship
Choi, Hee-Jong ; Kim, Jin ; Van, Suak-Ho ; Park, Il-Ryong ; Kim, Kwang-Soo ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 54~62
DOI : 10.3744/SNAK.2008.45.1.54
A new solution method was developed to solve the free surface flow around a hull and named as `Variable Free Surface Panel Method`. In the method the non-linearity of the free surface boundary conditions was fully taken into account and the raised panel method was employed to effectively solve the problem. The transom stern flow was also considered and the panel on the hull was generated using the panel cutting method. Numerical calculations were performed for KCS(KRISO Container Ship) hull form and compared with the experimental data to confirm the validity of the method. The comparison with the conventional free surface panel method was also accomplished. It is confirmed that new method gives more reliable results than the conventional method.
Time-Domain Analysis on Motion Response of Adjacent Multiple-Bodies in Waves
Kim, Kyong-Hwan ; Kim, Yong-Hwan ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 63~72
DOI : 10.3744/SNAK.2008.45.1.63
This study considers the motion response of multiple adjacent floating bodies in waves. As a method of solution, a three-dimensional Rankine panel method is adopted in time domain. For the validation of the developed numerical method, the motions of two adjacent Series 60 hulls and ship-barge model are estimated. The computational results are compared with other numerical and experimental analyses, showing favorable agreement.
Measurement Method of Broadband Dynamic Characteristics of Viscoelastic Material for Compliant Coating
Seoudi, Basel M. ; Boiko, Andrey V. ; Chun, Ho-Hwan ; Lee, In-Won ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 73~80
DOI : 10.3744/SNAK.2008.45.1.73
An improved method to measure the dynamic viscoelastic properties of elastomers is proposed. The method is based on the analysis of forced oscillation of a cylindrical sample loaded with inertial mass. No special equipment or instrumentation other than the ordinary vibration measurement apparatus is required. Typical measurement of the viscoelastic properties of a silicone rubber
S2 were measured over the wide frequency range from 10 Hz to 3 kHz under the action of wide region of deformation from
to 5%. It was shown that modulus of elasticity and loss tangent fall on the single curves when the ratio of load mass to sample mass changed from 1 to 20.
The Application of Structural Stress Method for the Fatigue Strength Assessment of Longi-web Connections
Kim, Myung-Hyun ; Kim, Jeong-Hwan ; Kim, Seong-Min ; Kim, Kwang-Seok ; Kang, Joong-Kyoo ; Heo, Joo-Ho ; Kang, Sung-Won ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 81~86
DOI : 10.3744/SNAK.2008.45.1.81
Recently, a mesh-size insensitive structural stress definition that provides a stress state at weld toe with relatively larger mesh size compared to conventional approaches has been proposed. The structural stress definition is based on the elementary structural mechanics theory and provides an effective measure of a stress state in front of weld toe. In this study, as an experimental validation of structural stress method in obtaining the fatigue strength of weldments, a series of fatigue test has carried out for longi-web connections, which are representative of ship-like structures. Based on the result from this study, it is expected to develop a more precise fatigue strength evaluation technique and to reduce time and cost associated with the fatigue design of ship and offshore structures.
An Experimental Study for the Fatigue Strength Assessment of Longi-web Connections
Kang, Sung-Won ; Kim, Jeong-Hwan ; Kim, Kwang-Seok ; Kang, Joong-Kyoo ; Heo, Joo-Ho ; Kim, Myung-Hyun ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 87~92
DOI : 10.3744/SNAK.2008.45.1.87
In the load-carrying fillet weldments, which are common in ship structures, fatigue cracks can occur at the weld root, in addition to the weld toe. In particular, fatigue cracks originating from the weld root are difficult to detect and cause a significant reduction in the fatigue strength of a weldment. Therefore, it is important to note the fatigue failure mode of load-carrying fillet weldment. In this study, a series of fatigue test was carried out for the fatigue strength evaluation of longi-web connections that are typical kinds of the load-carrying fillet weldment.
Development of Thermal Distortion Analysis Method on Large Shell Structure Using Inherent Strain as Boundary Condition
Ha, Yun-Sok ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 93~100
DOI : 10.3744/SNAK.2008.45.1.93
There are two ways of conventional thermal distortion analysis. One is the thermal elasto-plastic analysis and the other is the equivalent forces method based on inherent strain. The former needs exorbitant analysis time, while the latter cannot obtain results of stress field and it needs much time consumption with loads modeling on curved plates. Such faults in two methods have made difficulties in thermal distortion analysis of a large structure like ship hull. In order to solve them, new kind of thermal distortion analysis method was developed. We devised that the inherent strains was used as direct input factors in forms of boundary conditions. It was embodied by using thermal expansion coefficient in commercial code. We used the pre-calculated inherent strain as thermal expansion coefficient, and endowed nodes with imaginary temperatures. This method was already adopted at hull block welding distortion analysis which was considered as impossible, and gave productive results such as reduction of work time in the dry dock.
Study on the Development of Removing System for Waterbed Sediment by the Difference of Water Head
Lee, Young-Gill ; Son, Choong-Yul ; Jeong, Uh-Cheul ; Yu, Jin-Won ; Jeong, Kwang-Leol ; Kim, Kang-Sin ; Kim, Bang-Leol ;
Journal of the Society of Naval Architects of Korea, volume 45, issue 1, 2008, Pages 101~107
DOI : 10.3744/SNAK.2008.45.1.101
According to the existing research result on the seabed organic sediment, pollutants from the land and the sea contaminate the coastal water and sediment on the seabed. To tackle this problem, we need to dredge organic sediment. In the present paper, the development of removing system of seabed sediment by the difference of water head is researched by experimental method. For the validation of the decompression system, computations for validation are carried out for sediment removing equipment. The performance of inhalation equipment is analysed by some model tests.