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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 47, Issue 6 - Dec 2010
Volume 47, Issue 5 - Oct 2010
Volume 47, Issue 4 - Aug 2010
Volume 47, Issue 3 - Jun 2010
Volume 47, Issue 2 - Apr 2010
Volume 47, Issue 1 - Feb 2010
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Numerical Analysis of Violent Sloshing Problems by CCUP Method
Yang, Kyung-Kyu ; Kim, Yong-Hwan ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 1~10
DOI : 10.3744/SNAK.2010.47.1.001
In the present paper, a numerical method based on the constraint interpolation profile (CIP) method is applied for simulating two-dimensional violent sloshing problems. The free surface boundary value problem is considered as a multiphase problem which includes water and air. A stationary Cartesian grid system is adopted, and an interface capturing method is used to trace the shape of free surface profile. The CIP combined unified procedure (CCUP) scheme is applied for flow solver, and the tangent of hyperbola for interface capturing (THINC) scheme is used for interface capturing. Numerical simulations have been carried out for partially-filled 2D tanks under forced sway and roll motions at various filling depths and frequencies. The computational results are compared with experiments and/or the other numerical results to validate the present numerical method.
Numerical Simulation of Free Surface Flows Using the Roe`s Flux-difference Splitting Scheme
Shin, Sang-Mook ; Kim, In-Chul ; Kim, Yong-Jig ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 11~19
DOI : 10.3744/SNAK.2010.47.1.011
A code is developed to simulate incompressible free surface flows using the Roe`s flux-difference splitting scheme. An interface of two fluids is considered as a moving contact discontinuity. The continuities of pressure and normal velocity across the interface are enforced by the conservation law in the integral sense. The fluxes are computed using the Roe`s flux-difference splitting scheme for two incompressible fluids. The interface can be identified based on the computed density distribution. However, no additional treatment is required along the interface during the whole computations. Complicated time evolution of the interface including topological change can be captured without any difficulties. The developed code is applied to simulate the Rayleigh-Taylor instability of two incompressible fluids in the density ratio of 7.2:1 and the broken dam problem of water-air. The present results are compared with other available results and good agreements are achieved for the both cases.
Analysis of the Unstable Propeller Wake Using POD Method
Paik, Bu-Geun ; Kim, Kyung-Youl ; Kim, Ki-Sup ; Lee, Jung-Yeop ; Lee, Sang-Joon ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 20~29
DOI : 10.3744/SNAK.2010.47.1.020
The complicated flow characteristics of upper propeller wake influenced by hull wake are investigated in detail in the present study. A two-frame PIV (particle image velocimetry) technique was employed to visualize the upper propeller wake region. As the upper hull wake affects strongly propeller inflow, upper propeller wake shows much unstable vortical behavior, especially in the tip vortices. Velocity field measurements were conducted in a cavitation tunnel with a simulated hull wake. Generally, the hull wake generated by the hull of a marine ship may cause different loading distributions on the propeller blade in both upper and lower propeller planes. The unstable upper propeller wake caused by the ship`s hull is expressed in terms of turbulent kinetic energy (TKE) and is identified by using the proper orthogonal decomposition (POD) method to characterize the coherent flow structure in it. Instabilities appeared in the eigen functions higher than the second one, giving unsteadiness to the downstream flow characteristics. The first eigen mode would be useful to find out the tip vortex positions immersed in the unstable downstream region.
Development of the Weight Reduction Pump for Waterjet Propulsionl
Ahn, Jong-Woo ; Kim, Gun-Do ; Kim, Ki-Sup ; Park, Young-Ha ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 30~37
DOI : 10.3744/SNAK.2010.47.1.030
In order to control the weight balance of the waterjet propulsion ship, the pump`s weight needed to be decreased. We reduced length of pump hub, overall length of pump and chord length of impeller and stator. To keep pump efficiency and cavitation performance similar to the
design pump, optimum design and experiment were conducted. This paper describes experimental method and numerical analysis for pump design. At the blade design stage, performance analysis of the pump is conducted using commercial CFD codes (
,CFX-10). Required performance and cavitation characteristics of the design pumps were measured and observed using the stand-alone test apparatus. The weight of the pump was successfully decreased through a series of pump design processes composed of blade design, performance analysis and model test.
Numerical Study on Liquid Sloshing in the Three-dimensional Rectangular Tank with Various Baffle Heights
Lee, Chang-Yeol ; Yoon, Hyun-Sik ; Jung, Jae-Hwan ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 38~46
DOI : 10.3744/SNAK.2010.47.1.038
This study aims at investigating the effect of the baffle height on the liquid sloshing in the three-dimensional (3D) rectangular tank. In order to simulate the 3D incompressible viscous two-phase flow in the 3D tank with partially filled liquid, the present study has adopted the volume of fluid (VOF) method based on the finite-volume method which has been well verified by comparing with the results of the relevant previous researches. The ratio of the baffle height (
) to filling level (h) has been changed in the range of
to observe the effect on the impact loads on the side wall and free surface behavior. Generally, as baffle height increases, the impact pressure on the wall decreases and the deformation of free surface becomes weaker. However it seemed that a critical ratio of the baffle height existed to reveal the lowest impact pressure on the wall. Consequently, $h_B/h
Analysis of Dynamic Response of a Floating Crane and a Cargo with Elastic Booms Based on Flexible Multibody System Dynamics
Park, Kwang-Phil ; Cha, Ju-Hwan ; Lee, Kyu-Yeul ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 47~57
DOI : 10.3744/SNAK.2010.47.1.047
This study analyzes the dynamic response of a floating crane with a cargo considering an elastic boom to evaluate(or for evaluation of) its flexibility effect on their dynamic response. Flexible multibody system dynamics is applied in order to establish a dynamic equation of motion of the multibody system, which consists of flexible and rigid bodies. In addition, a floating reference frame and nodal coordinates are used to model the boom as a flexible body. The study also simulates the coupled surge, pitch, and heave motions of the floating crane carrying the cargo with three degrees of freedom by numerically solving the equation. Finally, the simulation results of the elastic and rigid booms are comparatively analyzed and the effects of the flexible boom are discussed.
Parallelized Topology Design Optimization of the Frame of Human Powered Vessel
Kim, Hyun-Suk ; Lee, Ki-Myung ; Kim, Min-Geun ; Cho, Seon-Ho ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 58~66
DOI : 10.3744/SNAK.2010.47.1.058
Topology design optimization is a method to determine the optimal distribution of material that yields the minimal compliance of structures, satisfying the constraint of allowable material volume. The method is easy to implement and widely used so that it becomes a powerful design tool in various disciplines. In this paper, a large-scale topology design optimization method is developed using the efficient adjoint sensitivity and optimality criteria methods. Parallel computing technique is required for the efficient topology optimization as well as the precise analysis of large-scale problems. Parallelized finite element analysis consists of the domain decomposition and the boundary communication. The preconditioned conjugate gradient method is employed for the analysis of decomposed sub-domains. The developed parallel computing method in topology optimization is utilized to determine the optimal structural layout of human powered vessel.
Experimental Investigations on the Fatigue Strength of the Submarine Pressure Hull
Kim, Uln-Yeon ; Kim, Kuk-Bin ; Jeon, Jae-Hwang ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 67~75
DOI : 10.3744/SNAK.2010.47.1.067
Submarine and deep sea diving structures are generally designed based on their ultimate strength. Fatigue strength at welded joint must be also taken into account because working stress is increased due to the increasing of diving depth and using high yield steel. The pressure hulls of submarine are subjected to fluctuating compressive loading. But in addition to the calculated stresses, high residual tensile stresses at welded part have to be considered. The state of stress level of pressure hull is tensile at surface and compressive at deep diving depth. This paper presents the results of an experimental investigation on the crack initiation and growth at the weld toe of T welded joints of HY-100 steel plate under constant amplitude loading. It is also investigated the phenomenon of the fatigue failure and test methods. Fatigue tests have been using real scaled local structural models of full penetration T-welded joint, which is a part of the cylindrical shell structures reinforced by ring stiffeners. Several load ratios under constant amplitude loading are considered in the tests. Crack initiation and growth characteristics are examined based on the beach marks of the cracked section of the test specimens. A design stress-life curve including the design formula is suggested according to tested data.
The Study on Risk and Redundancy Assessment Methodology of Ship Machinery System
Moon, Kyung-Tae ; Yang, Young-Soon ; Youn, Yeo-Pyo ; Ryu, Won-Sun ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 76~87
DOI : 10.3744/SNAK.2010.47.1.076
According to the new rules and regulations (New SOLAS), major safety critical systems are to be designed to be redundant, which is called `Redundancy Design`. This paper was to quantitatively analyze the degree of influence of the redundancy design applied to major safety critical systems using IMO`s FSA(formal Safety Assessment) method. For the purpose of this study, the diesel engine system, which is actually one of major safety critical systems, was dealt with FMEA, FTA and ETA technique. In addition, whether the redundancy was met or not was verified and the degree of safety, or redundancy, was represented in terms of reliability. In conclusion, the safety of propulsion systems is possibly assessed systematically by estimating the risk level in terms of frequency and fatality.
Design of Hybrid Magnet Wheels using 3D Finite Element Analysis for Wall-climbing Robot
Han, Seung-Chul ; Lee, Jae-Yong ; Kim, Jin-Ho ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 88~92
DOI : 10.3744/SNAK.2010.47.1.088
We propose a new design of the hybrid-magnet wheel to make it possible for a mobile robot to be attached to the vertical plane and be in motion. In the new suggested design, a permanent magnet is utilized to enhance the adhesive force, while an electromagnet is adopted to reduce the magnetic field and the adhesive force for detaching easily. To analysis the performance of the robot, 3 dimensional finite element analysis is executed using commercial electromagnetic analysis program, Maxwell. The results show that the adhesive force is reduced effectively by the electromagnet in the new designed robot system.
Ship Tests of PLC and Analysis of Its Signal Characteristics
Cho, Seong-Rak ; Paik, Bu-Geun ; Yi, Ji-Eun ; Lee, Dong-Kon ; Bae, Byung-Dueg ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 93~98
DOI : 10.3744/SNAK.2010.47.1.093
In this paper, PLC which can be installed easily and is stable to transfer datum, is tested for approving its application in a real ship. Internet access service, CCTV monitoring, light control and huge sensor communications are needed for enhancing the convenience and safety of passengers and crew in ships. In order to apply PLC in ships, we surveyed some noises interrupting PLC in ships and investigated the PLC characteristics. The Hannara, a training ship of Korea Maritime University, was used for the test. We measured and analyzed blocking noises using by NI`s SCXI-1001. When noises of specific frequency band occurred near the PLC frequency band, PLC transfer capacity was low for mass datum. We developed and verified some methods to apply PLC in a ship under lots of noises.
A Study on Optimized Rudder Design by Comparison and Analysis of Design Process of Rudder Device.
Kim, Sang-Hyun ; Kim, Hyun-Jun ; Jun, Hee-Chul ; Yoon, Seung-Bae ;
Journal of the Society of Naval Architects of Korea, volume 47, issue 1, 2010, Pages 99~111
DOI : 10.3744/SNAK.2010.47.1.099
Recently, a very large vessel`s maneuvering performance, rudder performance and rudder design`s importance is considered to be an important subject. There have been few studies on the design process of rudder device before. The aim of this paper is to investigate a design process of rudder device and to propose a generalized design process of rudder device. Firstly, we investigated the rudder device design process of Korean major shipyards. And the differences of a torque calculation method, rudder section design, maneuvering performance examination method, etc were analyzed theoretically. Secondly, the design process of rudder device was divided into concept design, initial design and detail design. In concept design, a rudder area was estimated and its validity was examined. In initial design, rudder profile and design method has been selected through rudder form determination process. And principal dimension and steering gear capacity were determined. Maneuvering performance was also examined by simulation tool. In detail design, design criteria considered in rudder initial design has been investigated thoroughly. Also a rudder torque, rudder cavitation performance and rudder structure analysis were estimated. And maneuvering performance was also examined by model test. Finally, based on the results of investigation, the design process of rudder device was generalized and proposed.