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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 31, Issue 4 - Nov 1994
Volume 31, Issue 3 - Aug 1994
Volume 31, Issue 2 - May 1994
Volume 31, Issue 1 - Feb 1994
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A Study on the Adaptable Conceptual Design System Based on Super-Application Concept
Dong-Kon Lee ; Kyung-Ho Lee ; Soon-Sub Lee ; Kyu-Yeul Lee ; Soon-Hung Han ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 1~6
A computer system supporting conceptual design is required to have not only a design model for creative works but also flexibility to cope with changing environments. In this research, a new conceptual design system was developed by expanding functions of existing systems. The modules of the system were maintained to have independency so that each unit module could be executed alone. The adaptable conceptual design system based on the super-application concept which control each module in high level was developed using UNIX C Shell of SUN SPARC workstation.
A Study on the Interactive Preliminary Hull Form Design by Hull Form Transformation Technique
Soon-Sub Lee ; Kyu-Yeul Lee ; Won-Soo Kang ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 7~14
This paper describes the development of the interactive hullform transformation program. This program has many hull transformation functions such as main particular transformation, deadrise generation, section characteristic transformation, local transformation and CB, LCB variation, etc. MBASTRANS adopted the GUI(Graphical User Interface) using the OSF/Motif based on the X-Window system and used X-PLOT and GLBAX which are 2 and 3 dimensional graphic libraries, respectively. The interface module cans generate the information of the hullform for the SIKOB package and the hydrodynamic analysis.
A Basic Study on the Fairing Method of Ship Hull Surface
D.J. Kim ; T.K. Yoon ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 15~21
In the previous researches on mesh curve fairing method, a set of discrete data points in a mesh can be selected as variables. End tangent vectors can not be variables. This restriction makes some problems in preparing the end tangent vectors at the bow or stern parts, because their slopes are not infinites or zeros. In this paper end tangent vectors are included as variables and the more smooth results are obtained. Also two methods of constructing ship hull surface from mesh curves are examined. It is shown that the skinning method is better than non-uniform B-spline fitting method in representing the area near boundary. The generation of a ship surface is given as an example.
On the Development of Speed Trial Data Measurement and Processing System
Man-Cheol Han ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 22~28
A data acquisition and processing system. using an IBM PC, an AD converter, and a printer, has been developed to monitor rapidly and significantly varying signals. The sister takes live signals and computes and displays the trend of the moving averages of the signals in real time. The system has been applied to monitor the shaft horsepower and revolution and the speed of ships for their speed trial. The reliable interpretation of the measured data using moving average can eliminate unnecessary arguments between the owner and yard on the performance of the newly built ships. Other applications of the system-inspection of engine hunting, providing data for ship maneuvering analysis, vibration data analysis, extending to the ship performance monitoring system-are also demonstrated and discussed.
A Study on the Whirling Critical Speeds of Marine Propeller Shafts
Yong-Chul Kim ; Gun-Do Lee ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 29~37
In this paper the modelling procedure and analysis technique for the prediction of accurate critical speeds of marine propeller shafts are suggested. As a solution method the transfer matrix method is employed to calculate the critical speeds, which are correspond to natural frequencies of the shaft in lateral vibration, and whirling responses. Furthermore, in order to check the validity of the simple prediction formulae, such as Jasper's formula and Panagopulos's formula, numerical calculations were performed. From the numerical results it was found that the critical speed of the propeller shaft is sensitive to the position and the supporting conditions of journal bearings.
Study on the Control Algorithms for the Auto-Pilot System
Sang-Hyun Suh ; Yong-Gyu Song ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 38~44
Control Algorithms of the Auto-Pilot system have been studied for the navigational economics and crew's comfortability since 1960's, when Auto-Pilot system was installed on the trans-ocean ships. At the beginning the PD control algorithm was used with the weather adjust function introduced to reduce the response of the auto-pilot system to the high frequency wave excitation in rough sea. In this study, the optimal and adaptive control theories are applied for the auto-pilot control algorithm. And those two algorithms are compared through the pre-defined cost function to obtain the most effective control technique for the Auto-Pilot system. The parameterization of the ship meneuvering equation for the adaptive control algorithm design procedure was examined and the advantage of the adaptive control was found through the simulation result with the wrong initial parameter value.
Time-Domain Simulation of Nonlinear Free-Surface Flows around a Two-Dimensional Hydrofoil
Yong-J. Kim ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 45~56
A computationally efficient numerical method based on potential flow is developed for time-domain simulation of the nonlinear free-surface flows around a 2-dimensional hydrofoil. This numerical method, namely, spectral/boundary-element method, is a mixed one of the high-order spectral method and the boundary-element method in time-domain. The high-order spectral method is used to calculate the nonlinear evolution of free-surface, and the boundary-element method is used to calculate the effects of the hydrofoil and the shed vortex. As application examples, nonlinear free-surface flows around a 2-dimensional hydrofoil which starts from the rest and translates near the free-surface with or without harmonic oscillations are calculated. Nonlinear/unsteady results of free-surface waves and hydrodynamic farces are shown and discussed. Particularly, the results of steady-state which are obtained as a special case of the present unsteady solution are compared with others' calculated and experimental results, and good agreements are observed.
Monte-Carlo Simulations of Nonlinear Systems to Non-White Excitation
D.W. Kim ; S.H. Kwon ; D.D. Ha ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 57~64
The subject of this paper is the simulation of a nonlinear stochastic differential equation. The Monte-Carlo solution of stochastic problems is applied to solve it. The method has been applied to problems involving nonlinear rolling motion of ships in irregular waves. These results are compared with those obtained by the stochastic linearization method and the equivalent nonlinear equation method to demonstrate its usefulness.
Application of Optimal Control Techniques to SWATH Motion Control
Chan-Wook Park ; Bo-Hyeon Heo ; Chun-Tae Song ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 65~77
This paper presents a derailed application procedure of the linear quadratic(LQ) theory for a SWATH heave and pitch control. A time domain model of coupled, linear time-invariant second order differential equations is derived from the frequency response model with the frequency dependent added mass and damping approximated as constant values at the heave natural frequency. Wave exciting forces are modeled as a sum of sinusoids. A systematic selection procedure of state and control weighting matrices is presented to obtain good transient behavior and acceptable fin movement. The validity of this controller design process is throughly investigated by simulations both in time domain and frequency domain and singular value plots of transfer function matrices. The finally designed control system shows good overall performances revealing that the applicability of the present study is proved successful.
Analysis of Impact Forces Acting on a Flat Faced Body Entering Water
Chang-Gu Kang ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 78~85
Impact forces are acting on the fore part of a body entering water and those are function o the shape of the fore part and entrance angle. In this paper, impact forces are computed for the flat faced body with arbitrary entrance angle The geometric characteristics of the wetted surface of the body are complicated. The surface is divided into several smooth parts and each of them is represented by a bi-cubic B-spline. The free surface condition,
, is applied at the undisturbed free surface and he boundary value problem is analized by using Green's function.
Considerations of the Initial Crack Damage Effect on the Advanced Idealized Plate Unit
Jeom-K. Paik ; Heung-W. Suh ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 86~90
This paper attempts to incorporate the initial crack damage effect into the existing idealized plate unit. For this purpose, a new concept which indicates the equivalent, reduced material properties due to initial cracks at the structural unit level, not at he microscopic aspect, is suggested, and a simplified mechanical plate model for the initially cracked plate in axial tension is formulated as a function of initial crack length, based on the finite-element solutions obtained by crack propagation analysis.
An Efficient Dynamic Optimization Method for Large Structures with Frequency Constraints
B.H. Kim ; T.Y. Chung ; K.C. Kim ;
Journal of the Society of Naval Architects of Korea, volume 31, issue 2, 1994, Pages 91~98
An efficient optimization procedure combining the frequency approximation technique and the component-mode synthesis method is proposed for the structural dynamic optimization of the large structures subject to prescribed natural frequency constraints. Frequency constraints are approximated by using the first-order sensitivities with respect to both design parameters and their reciprocals. The component-mode synthesis method proposed by the authors in Ref. is used for the repetitive detail finite-element analysis and sensitivity analysis. The validity of the proposed optimization procedure is confirmed through the numerical implementation of some examples. The presented approximation technique requires much smaller number of repetitive analysis than that using the sensitivities with respect to design parameters only, and further improvement in the numerical efficiency is achieved by the adoption of the introduced component-mode synthesis.