• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.251-258
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• 1993

The main purpose of this paper is to present both the natural frequencies and the buckling loads of beam-columns on Winkler-type foundations. The ordinary differential equations governing the free vibrations and the buckling loads of beam-columns on Winkler-type foundation are derived as nondimensional forms. The Runge-Kutta method and Determinant Search method are used to perform the integration of the differential equations and to determine the eigenvalues(natural frequencies and buckling loads), respectively. Hinged-hinged and damped-clamped end constraints are applied in numerical examples. The relation between frequency parameter and elastic foundation parameter is presented in figure. The effects of axial loads on the natural frequencies of beam-columns on elastic foundations are investigated and the relation between buckling load parameter and elastic foundation parameter is also analyzed. The relation between foundation rested ratio and frequency parameter, buckling load parameter are investigated. The beam-columns on non-homogeneous elastic foundation are analyzed and typical mode shapes are also presented.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.257-262
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• 2008

Design and analysis of road subgrade system, which is exposed to repetitive loading condition, uses resilient modulus. The behavior of railway subgrade system will not be quite different from that of road system. Following this phenomenological feature of the subgrade system, this paper introduces the implementation of the resilient modulus based constitutive model on a commercial finite element software. The implementation of the resilient modulus models such as K-${\theta}$ and Uzan on a FE program has been conducted previously. These model assumes that the material state reaches to the nonlinear elastic condition and with further application of repetitive loads, the response of material is completed in elastic condition. According to the recent test results performed on cohesive subgrade soils, however, permanent deformation occurs with repetitive loads. With aids of previously suggested models the permanent deformation cannot be modeled. To overcome such limitation a plastic potential derived from the test results and simple failure criterion based constitutive model is developed. The comparison between the analysis and test results shows a good correlation.

• Journal of KSNVE
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• v.8 no.6
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• pp.1172-1180
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• 1998

Elastic wave scattering from an acoustically rigid or soft object is studied and compared with the acoustic wave scattering. The behavior of phases as well as magnitudes of partial waves and their total summation of scattered wave are numerically analyzed and discussed. The effect of mode conversion, which occurs between longitudinal and transversal waves in elastic wave scattering. on the magnitudes and phases of scattered waves is identified.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.1
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• pp.69-79
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• 2001

A volume integral equation method(VIEM) is applied for the effective analysis of elastic wave scattering problems in unbounded solids containing general anisotropic inclusions. It should be noted that this newly developed numerical method does not require the Green's function for anisotropic inclusions to solve this class of problems since only the Green's function for the unbounded isotropic matrix is Involved In their formulation for the analysis. nis new method can also be applied to general two-dimensional elastodynamic problems with arbitrary shapes and number of anisotropic inclusions. Through the analysis of plane elastodynamic problems in unbounded isotropic matrix with an orthotropic inclusion, it is established that this new method is very accurate and effective for solving plane elastic problems in unbounded solids containing general anisotropic inclusions.

• Proceedings of the Acoustical Society of Korea Conference
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• 1985.10a
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• pp.16-18
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• 1985

탄성 원통형 Shell에서의 산란 이온을 수치해석을 이용하여 전산 프로그램화하였다. 이 프로그램을 통하여 탄성 원통형 Shell의 주파수, 재질, 두께에 따른 산란형태 변화를 고찰하였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1996.05a
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• pp.24-29
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• 1996

본 연구에서는 베어링 하우징의 탄성 변형을 고려한 커넥팅 로드 베어링의 탄성 유체 윤활 해석을 통해 축 중심의 궤적, 최소 유막 두께 변화, 최대 유막 압력 변화를 예측하였다. 베어링 하우징의 탄성 변형을 고려한 해석 결과 강체 해석 결과보다 축의 편심율과 최소 유막 두께는 크게, 최대 유막 압력은 낮게 예측되었다. 또 축의 회전 속도가 증가할수록, 실린더 압력이 증가할수록 최소 유막 두께는 감소하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.224-227
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• 2011

케이블구조의 기하학적 비선형해석을 위한 탄성포물선 케이블요소를 제시한다. 탄성현수선 케이블요소에 대한 적합조건과 접선강도행렬을 토대로 장력이 충분히 도입되어 자중에 의한 처짐 형상이 포물선에 가깝다는 가정 하에서 무응력길이를 포함하는 탄성포물선 케이블요소의 비선형 힘-변형관계식과 접선강도 행렬을 구한다. 또한 현(chord)방향으로 두 케이블요소의 등가 공칭장력식을 정의한다. 탄성포물선 케이블 요소의 수치적인 정확성을 확인하기 위하여, 경사진 케이블을 탄성현수선과 탄성포물선 케이블요소로 각각 모델링하여 매개변수 해석을 수행하고 비교, 분석한 결과를 제시한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.2
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• pp.133-140
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• 2005

A Plate on the elastic half-space may be generally be analyzed by the finite element method. However, there ate some difficulties to obtain the flexibility matrix of the foundation based on the Boussinesq's theory. In this study, an efficient numerical procedure which uses the analysis results of the vertical displacements due to the uniformly distributed loading in a circular area is presented. Some numerical examples represent better results than those of numerical integration technique or subsection method especially in the case of irregular mesh pattern.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6A
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• pp.617-624
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• 2009

This study deals with the free vibrations of the elastica shaped arch with linear taper. The shape of elastica is obtained from the Bernoulli-Euler beam theory. Differential equations governing free vibrations of such arch are derived and numerically solved to determine natural frequencies, in which three kinds of taper type and two kinds of end constraint, respectively, are considered. For validating the theories presented herein, the frequency parameters obtained in this study are compared to those of SAP 2000. As results of the numerical analyses, effects of end constraint, taper type, slenderness ratio and section ratio on the lowest four non-dimensional frequency parameters are extensively investigated.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.1 s.41
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• pp.9-16
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• 2005

The purpose of this paper is to present a design procedure of a friction damper for controlling elastic and inelastic responses of building structures under earthquake excitation. The equivalent damping and period increased by the friction damper are estimated using ATC-40 and ATC-55 procedures which provide equivalent linear system for bilinear one, and then a design formula to achieve target performance response level by the friction damper is presented. It is identified that there exists error between the responses obtained by this formula and by performing nonlinear analysis and the features of the error vary according to the hardening ratio, yield strength ratio, and structural period. Equations for compensating the error are proposed based on the least square method, and the results from numerical analysis indicate that the error is significantly reduced. The proposed formula can be used without much error for designing a friction damper for retrofitting a structure showing elastic or inelastic behavior.