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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
Journal Basic Information
Journal DOI :
The Society of Naval Architects of Korea
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Volume & Issues
Volume 40, Issue 6 - Dec 2003
Volume 40, Issue 5 - Oct 2003
Volume 40, Issue 4 - Aug 2003
Volume 40, Issue 3 - Jun 2003
Volume 40, Issue 2 - Apr 2003
Volume 40, Issue 1 - Feb 2003
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A Study on the Effects of the Period Control Device of Anti-Rolling Tanks
Journal of the Society of Naval Architects of Korea, volume 40, issue 1, 2003, Pages 1~7
DOI : 10.3744/SNAK.2003.40.1.001
The effect of the passive anti-rolling tanks(ART) decreases when the roll period of the vessel does not match the designed oscillating period of the fluid in the tank. In order to improve the effect of the passive ART, the damping plates are installed in the lower duct of the ART to adjust the oscillating period of the fluid. The effects of the damping plates on the oscillating period of the fluid and the changes of the stabilizing moments are examined through the series of bench tests. Acryl model tank larger than 1m breadth is made to minimize the viscous effect of the tank and the stabilizing moments of the tank are measured for various roll angles. Using the obtained tank damping coefficient, RAO(Response Amplitude Operator) value in the resonance range is computed and the stabilizing effect of a ART has been estimated.
A Study on the Design Parameters of Controller for Dynamic Positioning System
Journal of the Society of Naval Architects of Korea, volume 40, issue 1, 2003, Pages 8~19
DOI : 10.3744/SNAK.2003.40.1.008
Special purpose vessels such as drillship and ocean research vessels install the DPS(Dynamic Positioning System) to maintain the position and heading for long-time operation. This paper deals with the design parameters for the control theory and filter algorithms of DP system. for the environmental loadings wind forces, current forces and wave forces were considered. In order to estimate the low frequency motions without first-order wave motion, the Kalman filter was used and it was assumed that the first-order wave forces correspond to system noises and first-order wave motions are measurement noises. In this simulation, the length of research vessel is 65 meters and it has four thrusters to maintain the position. The ability of keeping position and heading was confirmed. For the calculation of thruster input the LQR and LOI control theory were adopted and the effects of gain were investigated.
Nonlinear Motion Analysis of FPSO with Turret Mooring System
Journal of the Society of Naval Architects of Korea, volume 40, issue 1, 2003, Pages 20~27
DOI : 10.3744/SNAK.2003.40.1.020
The FPSO is moored by mooring lines to keep the position of it. The nonlinear motion analysis of the moored FPSO must be carried out in the initial design stage because sea environments affect motion of it. In this paper, the mathematical model is based on the slow motion maneuvering equations in the horizontal plane considering wave, current and wind forces. The direct integration method is employed to estimate wave loads. The current forces are calculated by using mathematical model of MMG. The turret mooring forces are quasi-statically evaluated by using the catenary equation. The coefficients of a model for wind forces are calculated from Isherwood's experimental data and the variation of wind speed is estimated by wind spectrum according to the guidelines of API-RP2A. The nonlinear motions of FPSO are simulated under external forces due to wave, current, wind including mooring forces in time domain.
Fatigue Strength of Fillet Weldment under Out-of-plane Bending Load
Journal of the Society of Naval Architects of Korea, volume 40, issue 1, 2003, Pages 28~35
DOI : 10.3744/SNAK.2003.40.1.028
Fatigue tests of transverse fillet weldment were performed under out-of-plane bending loads. Significant increase of the fatigue strength was observed under out-of-plane bending loads, compared to the one under in-plane loads (axial loads). Applicability of the crack propagation analysis using LEFM for the surface crack of fillet weldment were investigated as well, in parallel with the fatigue tests. For the rational assessment of the fatigue strength of welded ship structures where combined stresses of the in-plane axial stress and the out-of-plane bending stress are induced simultaneously due to complexity of applied load and structural geometry, further investigation is recommended for the effect of the out-of-plane bending stress on the fatigue strength of weldment.
Numerical Analysis on the Affection of Lumped Attachments to the Vibration Power Flow in Cross-stiffened Plate
Journal of the Society of Naval Architects of Korea, volume 40, issue 1, 2003, Pages 36~46
DOI : 10.3744/SNAK.2003.40.1.036
To investigate the affection of lumped mass and spring on the vibration power flow of cross-stiffened plate experiencing bending vibration, structural intensity analysis is done using the modal analysis based on assumed mode method. The numerical analysis is carried out varying the mass and spring constant and their attached positions. The results show that both the spring and the mass may cause to large variation of not only vibratory displacement but also vibratory power flow patterns in case of little change of natural frequencies, and the attachments near to excitation location can effectively reduce the magnitude of maximum structural intensity.
Research on the production system of FRP ship based on the cooperative work
Journal of the Society of Naval Architects of Korea, volume 40, issue 1, 2003, Pages 47~54
DOI : 10.3744/SNAK.2003.40.1.047
The majority of small/medium sized shipbuilders in Korea is poor in capital and then, should be restructured as an efficient production system with low investment. Due to considering this situation, the cooperative work system is proposed, in this study, as more effective production system for small/medium sized shipbuilder The cooperative work system Is the production system that many small/medium sized shipbuilders in a group jointly share the common facilities except minimum equipments and have managerial cooperation such as joint purchase of raw materials. The efficiency of cooperative work system is proved from economic and technical point of view with the case study of FRP shipbuilders of Sapjin industrial complex located at Mokpo area.
Development of FRP Waste Recycling Technology by Property Invesitigation and Polymer Cement Mortar Manufacturing
Kim, Yong-Seop ;
Journal of the Society of Naval Architects of Korea, volume 40, issue 1, 2003, Pages 55~62
DOI : 10.3744/SNAK.2003.40.1.055
This study has investigated physical and chemical properties of FRP waste, has manufactured polymer cement mortar using a crushed waste with sand and has evaluated its capability to develop the economical waste recycling technology. The study has investigated tension strength, hardness test and impact test as physical properties and also thermogravimetric characteristics and analyzed infrared spectroscope as chemical properties. Then the study has manufactured polymer cement mortar and has analyzed how the FRP waste fine aggregate replacement ratio has an effect on compression strength. Noticing admixture can complement strength drop occurred by the FRP waste fine aggregate replacement, the study examined an optimum rate of admixture addition and its reaction through electron microscope photos.
A Note on the Hull Form Variational Methods
Journal of the Society of Naval Architects of Korea, volume 40, issue 1, 2003, Pages 63~68
DOI : 10.3744/SNAK.2003.40.1.063
Systematic geometrical variation method of hull forms, such as "1 -Cp", "Swinging" and "Lackenby" are widely used in the early stage of a new design from those of a similar parent ship, which shows a better performance through the model test and/or sea trials. This method is simple and easy to modify original hull forms without changing the main characteristics. The shape of the prismatic curie can be easily varied by these methods, however, the frame line shape in the body plan can′t be generated easily, when the section shapes are complicated or have discontinuities or the mismatch of the body plan and the stem and stern profiles. To overcome this drawback of the hull form variations, a simple and useful method has been proposed in the present study.
A Study on Optimization of Neuro-fuzzy System Parameter using Taguchi Method
Journal of the Society of Naval Architects of Korea, volume 40, issue 1, 2003, Pages 69~73
DOI : 10.3744/SNAK.2003.40.1.069
Neuro-Fuzzy System is to combine merits of fuzzy inference system and neural networks. The neuro-fuzzy system applies a information about given input-output data to fuzzy theories and deals these fuzzy values with neural networks, e.g. first, redefines normalized input-output data as membership functions and then executes thses fuzzy information with backpropagation neural networks. This paper describes an innovative application of the Taguchi method for the determination of these parameters to meet the training speed and accuracy requirements. Results drawn from this research show that the Taguchi method provides an effective means to enhance the performance of the neuro-fuzzy system in terms of the speed for learning and the accuracy for recall.