• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.799-808
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• 1991

본 연구에서는 연속체 역학의 에너지 원리에서 출발하여, 동적 비선형 해석을 위한 유한요소 식들을 유도하고, 이를 이용하여 특이 경계조건을 갖는 고체의 대변위 동적 선형 현상과 비선형 현상에 관하여 연구하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.5
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• pp.481-486
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• 2012

We discuss the design, fabrication, and testing of a large-displacement electromagnetic actuator with the meander springs partially exposed to a magnetic field. We compared two prototypes: a prototype (F) of the conventional actuator with the meander springs fully exposed to a magnetic field and a prototype (P) of the proposed actuator with the meander springs partially exposed to a magnetic field. For a 5 Hz square input current varying from 10.40 mA, P showed an increase of $16.9{\pm}1.2%$ in the amplitude, which was greater than the increase in the case of F. Thus, we experimentally demonstrated the large-displacement actuation performance of the proposed actuator in a small volume and at low currents (below 40 mA). The proposed electromagnetic actuator can be used for low-power and large-displacement manipulation of optical switches and optical choppers.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.550-555
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• 2001

This paper presents a nonlinear modeling method for dynamic analysis of flexible structures undergoing overall motions that employs the mode approximation method. This method, different from the naive nonlinear method that approximates only Cartesian deformation variables, approximates not only deformation variables but also strain variables. Geometric constraint relations between the strain variables and the deformation variables are introduced and incorporated into the formulation. Two numerical examples are solved and the reliability and the accuracy of the proposed formulation are examined through the numerical study.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.1014-1019
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• 2003

A dynamic modeling method for beams undergoing overall rigid body motion is presented in this paper. Two special deformation variables are introduced to represent the stretching and the curvature and are approximated by the assumed mode method. Geometric constraint equations that relate the two special deformation variables and the cartesian deformation variables are incorporated into the modeling method. By using the special deformation variables, all natural as well as geometric boundary conditions can be satisfied. It is shown that the geometric nonlinear effects of stretching and curvature play important roles to accurately predict the dynamic response when overall rigid body motion is involved.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.683-684
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.667-668
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.205-206
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.464-465
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.371-372
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• 2010

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.4
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• pp.45-54
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• 2008

The purpose of this study was to investigate the performance of precast segmental PSC bridge columns with regard to P-delta effects. A model of precast segmental PSC bridge columns was tested under a constant axial load and a cyclically reversed horizontal load. A computer program, RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), was used for the analysis of reinforced concrete structures. In addition to the material nonlinear properties, an algorithm for the problem of large displacement that may result in additional deformation has been formulated using total Lagrangian formulation. This study documents the testing of precast segmental PSC bridge columns under cyclic loading, and presents conclusions based on the experimental and analytical findings.