• International Journal of Control, Automation, and Systems
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• v.6 no.6
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• pp.928-938
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• 2008

This study presents an approach for approximation an unknown function from a numerical data set based on the synthesis of a neuro-fuzzy model. An adaptive input data space parting method, which is used for building hyperbox-shaped clusters in the input data space, is proposed. Each data cluster is implemented here as a fuzzy set using a membership function MF with a hyperbox core that is constructed from a min vertex and a max vertex. The focus of interest in proposed approach is to increase degree of fit between characteristics of the given numerical data set and the established fuzzy sets used to approximate it. A new cutting procedure, named NCP, is proposed. The NCP is an adaptive cutting procedure using a pure function $\Psi$ and a penalty function $\tau$ for direction the input data space parting process. New algorithms named CSHL, HLM1 and HLM2 are presented. The first new algorithm, CSHL, built based on the cutting procedure NCP, is used to create hyperbox-shaped data clusters. The second and the third algorithm are used to establish adaptive neuro- fuzzy inference systems. A series of numerical experiments are performed to assess the efficiency of the proposed approach.

• Structural Engineering and Mechanics
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• v.73 no.1
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• pp.65-73
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• 2020

The present work describes a new time marching procedure for structural dynamics analyses. In this novel technique, time integration parameters are automatically evaluated according to the properties of the model. Such parameters are locally defined, allowing the user to input a numerical dissipation property for each element, which defines the amount of numerical dissipation to be introduced. Since the integration parameters are locally defined as a function of the structural element itself, the time marching technique adapts according to the model, providing enhanced accuracy. The new methodology is based on displacement-velocity relations and no computation of accelerations is required. Furthermore, the method is second order accurate, it has guaranteed stability, it is truly self-starting and it allows highly controllable algorithm dissipation in the higher modes. Numerical results are presented and compared to those provided by the Newmark and the Bathe methods, illustrating the good performance of the new time marching procedure.

• Structural Engineering and Mechanics
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• v.68 no.6
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• pp.713-720
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• 2018

In this paper a new numerical method to determine the elastic curve of the simply supported beams of variable cross-section is demonstrated. In general case it needs to solve linear or small nonlinear second order differential equations with prescribed boundary conditions. For numerical solution the initial values of the slope and the deflection of the end cross-section of the beam is necessary. For obtaining the initial values a lively procedure is developed: it is a special application of the shooting method because boundary value problems can be transformed into initial value problems. As a result of these transformations the initial values of the differential equations are obtained with high accuracy. Procedure is applied for calculating of elastic curve of a simply supported beam of variable cross-section. Results of these numerical procedures, analytical solution of the linearized version and finite element method are compared. It is proved that the suggested procedure yields technically accurate results.

• Computers and Concrete
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• v.3 no.1
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• pp.17-28
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• 2006

Replacement of actual stress distribution in a reinforced concrete (RC) flexural member with a simpler geometrical shape, which maintains magnitude and location of the resultant compressive force, is an acceptable conceptual trick. This concept was originally perfected for normal strength concrete. In recent years, high strength concrete (HSC) has been introduced and widely used in modern construction. The stress block parameters require updating to account for special features of HSC in the design of flexural members. In future, more varieties of concrete may be developed and a corresponding design procedure of RC flexural members will be required. The usual practice is to conduct large number of experiments on various sizes of specimen and then evolve an empirical relation. This paper presents a numerical procedure through which the stress block parameters can be numerically derived for a given strain ratio variation. The material model for concrete is presented and computational procedure is described. This procedure is illustrated with several variations of strain ratio. The advantages of numerical procedure are that it costs less and it can be used with new material models for any new variety of concrete.

• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.202-206
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• 2005

A new numerical scheme for two-phase flows, the Hybrid VOF method has been developed for improved free surface capturing. The present new method is a volume capturing based VOF method coupled with a reinitialization procedure of a Level-set method. For validation, the proposed method is applied to two test cases: spherical bubble rising and dam breaking. The calculated results by using the Hybrid VOF method with the two previously applied VOF formulations are compared with available numerical and experimental data. It is found that the new method provides more accurate results than the two previous ones.

• Journal of Mechanical Science and Technology
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• v.14 no.3
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• pp.331-337
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• 2000

A numerical procedure for contact analysis and calculating subsurface stress was developed. The procedure takes the advantage of signal processing technique in frequency domain to achieve shorter computing time. Boussinesq's equation was adopted as a response function in contact analysis. The validity of this procedure was proved by comparing the numerical results with the exact solutions. The fastness of this procedure was also compared with other algorithm.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.2 s.140
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• pp.88-97
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• 2005

A new numerical scheme solving two-phase flow, the Hybrid VOF method for improved free surface capturing has been developed by combining a volume capturing VOF method with the Level-Set reinitialization procedure. For validation, the proposed method is applied to 3-D bubble rising problem, dam breaking and the free surface flow around a commercial container ship. The calculated results by using the Hybrid VOF method with the two previously applied VOF formulations are compared with available numerical and experimental data. It is found that the new method provides more reasonable results than the two previous ones.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.2
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• pp.228-239
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• 1992

The purpose of the present research is to develop an efficient numerical method for the calculation of potential flow and predict the wave-making resistance for the application to ship design of tuna purse seiner. The paper deals with the numerical calculation of potential flow around the series 60 with forward velocity by the new slender ship theory. This new slender ship theory is based on the asymptotic expression of the Kelvin-source, distributed over the small matrix at each transverse section so as to satisfy the approximate hull boundary condition due to the assumption of slender body. Some numerical results for series 60, C sub(b) =0.6, hull are presented in this paper. The wave pattern and wave resistance are computed at two Froude numbers, 0.267 and 0.304. These results are better than those of Michell's thin ship theory in comparison with measured results. However, it costs much time to compute not only wave resistance but also wave pattern over some range of Froude numbers. More improvements are strongly desired in the numerical procedure.

• Journal of KSNVE
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• v.9 no.5
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• pp.966-974
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• 1999

This paper introduces modeling and its modal analysis procedure for exact and closed form solution of in-plane vibrations of general Timoshenko frame structures using exact dynamic element method(EDEM). The derivation procedure of the exact system dynamic matrices for Timoshenko beam frames is described. A new modal analysis procedure is also proposed since the conventional modal analysis schemes are not adequate for the proposed, exact system dynamic matrix. The proposed method provides exact modal parameters as well as all kinds of closed form solutions for general frame structures. Two numerical examples are presented for validating and illustrating the proposed method. The numerical study proves that the proposed method is useful for dynamic analysis of frame structures.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.76-83
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• 2001

In this study, a new method coupling of Element-Free Galerkin(EFG) method and Infinite Elements(IE) method is presented for extending application of the EFG method to engineering problems in unbounded domain. EFG method and IE method are briefly reviewed, and then the coupling procedure of the two methods is proposed. Numerical Algorithm by way of EFG-lE coupling technique is also developed. Numerical results illustrate the performance of the proposed technique. The accuracy of numerical solutions by the developed algorithm is guaranteed in comparing those of the other methods.