• Journal of applied mathematics & informatics
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• 제29권1_2호
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• pp.145-159
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• 2011

The numerical solution to the linear and nonlinear and linear system of Fredholm and Volterra integral equations of the second kind are investigated. We have used crooked lines which includ the nodes specified by modified rationalized Haar functions. This method differs from using nominal Haar or Walsh wavelets. The accuracy of the solution is improved and the simplicity of the method of using nominal Haar functions is preserved. In this paper, the crooked lines with unknown coefficients under the specified conditions change the system of integral equations to a system of equations. By solving this system the unknowns are obtained and the crooked lines are determined. Finally, error analysis of the procedure are considered and this procedure is applied to the numerical examples, which illustrate the accuracy and simplicity of this method in comparison with the methods proposed by these authors.

• 한국정밀공학회지
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• 제9권4호
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• pp.118-125
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• 1992

Theoretical equations for hoop stress, longitudinal or meridian stress and Von Mises stress of an axismmetric conical pressure vessel and a frustum of conical pressure velle, both of which are pressuized by hydrostatic loading, are derived from equilibrium equations. The membrane stresses conputed by theoretical equations for a conical pressure vessel and a frustum of conical pressure vessel are compared with the values obtained from finite elelment method. Based on the fact that the computational values by theoretical equations are well agreed with the finite element results, derived equations are proved to be valid and it is possible for those equations to be conveniently used for structural analysis or design of frustum of conical pressure vessel which is a part of silo body.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.653-660
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• 2012

In this paper free vibration analysis of symmetric and cross-ply elastic laminated shells based on FSDT with two different boundary conditions(C-C, S-S) was performed through discretization of equations of motion and boundary condition. Model of laminated composite cylindrical shells subjected to a combination of magnetic and thermal fields is developed via Hamilton's variational principle. These coupled equations of motion are based on the electromagnetic equations (Faraday, Ampere, Ohm, and Lorenz equations) and thermal equations which are involved in constitutive equations. Variations of dynamic characteristics of composite shells with applied magnetic field, temperature gradient, and stacking sequence for each boundary conditions are investigated and pertinent conclusions are derived.

• 한국항공운항학회지
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• 제21권4호
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• pp.1-10
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• 2013

This paper addresses the derivation of 6-DOF equation of Tanker and Receiver's aircraft for aerial refueling. The new set of nonlinear equations are derived in terms of the relative translational and rotational motion of receiver aircraft respect to the tanker aircraft body frame. Further the wind effect terms due to the tanker's turbulence are included. The derivation of absolute dynamic equation for tanker aircraft written in the inertial frame is calculated from the relative dynamics equations of receiver. The derived relative and absolute equations are implemented the simulation in the same flight conditions to verify the relative motion and compare the trim results by using the MATLAB/SIMULINK program.

• 한국수학사학회지
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• 제24권1호
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• pp.31-44
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• 2011

라이만 다양체 위에서의 편미분 방정식의 연구는 미분기하학에서 중요한 연구 분야로 인식되어 왔다. 본 논문에서는 특히 최근에 미분기하학과 위상수학 분야에서 중요한 역할을 하고 있는 리이만 다양체 위에서의 포물형 방정식에 관한 역사적으로 주목받고 있는 중요한 연구 결과를 정리해 보고, 아울러 이 분야의 최근 연구 결과를 고찰한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.443-446
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• 2005

The shear strength equations of the joint with RC column and steel beam are used the proposed equations of ASCE, Kanno and AIJ but there are not applied variable joint details. Until now the variable experimental studies are practiced but the studies of predicted shear strength equation are not integrated and only the applicable equations to each case are proposed. The purpose of this study is statistical analysis for the proposed equations applied existing experiments. The proposed equations are ASCE, Kanno, M-Kanno, AIJ and M-AIJ. The 47 of shear failure experiments are used in this study The consequence is that the Kanno's equation is very analogized with the experimental result but ASCE equation underestimates about 42$\%$. AIJ and M-AIJ are not proper equations for estimating the shear strength of RCS joint.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.1165-1170
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• 2005

In order to perform the spatial buckling analysis of the curved beam element with nonsymmetric thin-walled cross section, exact static stiffness matrices are evaluated using equilibrium equations and force-deformation relations. Contrary to evaluation procedures of dynamic stiffness matrices, 14 displacement parameters are introduced when transforming the four order simultaneous differential equations to the first order differential equations and 2 displacement parameters among these displacements are integrated in advance. Thus non-homogeneous simultaneous differential equations are obtained with respect to the remaining 8 displacement parameters. For general solution of these equations, the method of undetermined parameters is applied and a generalized linear eigenvalue problem and a system of linear algebraic equations with complex matrices are solved with respect to 12 displacement parameters. Resultantly displacement functions are exactly derived and exact static stiffness matrices are determined using member force-displacement relations. The buckling loads are evaluated and compared with analytic solutions or results by ABAQUS's shell element.

• 한국해안해양공학회지
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• 제8권1호
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• pp.52-60
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• 1996

소류사 이동량 산정에 사용되는 여러 종류의 산정식들을 살펴보았다. 기존 산정식의 수식에 내포된 의미와 수식 전개과정 등을 종합적으로 검토하고 관측자료와의 비교로부터 각 산정식의 문제점을 파악하고자 하였다. 기존 산정식들의 종합적인 검토에 기초하여 개선방법을 제안하였으며, 보다 광범위하게 합리적으로 적용할 수 있는 여러 종류의 소류사량 산정식을 개발하였다. 각 형태의 산정식들을 Brownlie (1985)가 수집한 관측자료와 대비하여 산정식들에 도입된 경험 계수들을 조정하여 결정하였으며, 최종적으로 개선된 소류사량 산정식들을 관측자료와 대비하여 불일치률의 범위에 대하여 검토하였다.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.122-130
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• 2013

Rail geometries such as cant, grade and curvature can be easily represented by means of a track coordinate system. In this analysis, in order to derive a dynamic and constraint equation of a wheelset, the track coordinate system is used as an intermediate stage. Dynamic and constraint equations of railway vehicle bodies except the wheelset are written in the Cartesian coordinate system as a conventional method. Therefore, whole dynamic equations of a railway vehicle are derived by combining wheelset dynamic equations and dynamic equations of railway vehicle bodies. Constraint equations and constraint Jacobians are newly derived for the track coordinate system. A process for numerical analysis is suggested for the derived dynamic and constraint equations of a railway vehicle. The proposed dynamic analysis of a railway vehicle is validated by comparison against results obtained from VI-RAIL analysis.

• Structural Engineering and Mechanics
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• 제27권3호
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• pp.333-345
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• 2007

In this study, the nonlinear vibrations of stepped beams having different boundary conditions were investigated. The equations of motions were obtained using Hamilton's principle and made non dimensional. The stretching effect induced non-linear terms to the equations. Forcing and damping terms were also included in the equations. The dimensionless equations were solved for six different set of boundary conditions. A perturbation method was applied to the equations of motions. The first terms of the perturbation series lead to the linear problem. Natural frequencies for the linear problem were calculated exactly for different boundary conditions. Second order non-linear terms of the perturbation series behave as corrections to the linear problem. Amplitude and phase modulation equations were obtained. Non-linear free and forced vibrations were investigated in detail. The effects of the position and magnitude of the step, as well as effects of different boundary conditions on the vibrations, were determined.