• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.04a
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• pp.39-44
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• 1992

This paper proposes a method of h-type adaptive mesh generation for the finite element analysis of two dimensional elasticity problem. The error energy norm of a posteriori error estimation is difined based on the complementary energy of each element. Computer codes are developed and some examples are investigated. It is shown that the approach to the optimized mesh in this paper is effective and useful.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.623-628
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• 2002

A meshfree formulation for the calculation of energy band structure is presented. The conventional meshfree shape function is modified to handle the periodicity of Bravais lattice, and applied to the calculation of real-space electronic-band structure. Numerical examples include the Kronig-Penney model potential and the empirical pseudopotentials of diamond and zinc-blonde semiconductors. Results demonstrate that the meshfree method be a promising one as a real-space technique for the calculations of diverse physical band structures.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.231-238
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• 1997

Many methods have been proposed for achieving optimum performance of structures subjected to earthquake excitation. The conventional approach requires that structures passively resist earthquakes through a combination of strength, deformability, and energy absorption. Base isolation is a technique for mitigating the effects of earthquakes on structures through the introduction of flexibility and energy absorption capability. In this paper, a parametric study of effectiveness of isolation systems with various main structures' properties is carried out through the response spectrum analysis. It is shown that, most base isolators with its longer period and higher damping can significantly reduce the base shear force transmitted to the structures.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.04a
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• pp.1-5
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• 1990

The object of this study introducts simple formula being based on energy principle to investigate span truss's non-linear, and considers the relation of member's length, height rate and slenderness ratio to rise prymid truss's economic structure ability through each example. This paper considered space truss's geometric non-linear behavior and material non-linear behavior, so acquired under result through as saying energy principle.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.696-703
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• 2005

Recently, the collision problems between a bridge and a navigating ship are frequently issued at the stage of structure design. Even the many study results about vessel to vessel collision are presented, but the collision studies between vessel and bridge structure have been hardly presented. In this study, nonlinear dynamic analysis of vessel and fender system carry out using ABAQUS/Explicit commercial program with consideration of some parameters, such as bow structure we composed to shell element also ship's hull is modeling to beam element. Also, buoyancy effect is considered as spring element. The two types of fender systems was comparable with both collision analysis about steel materials fender system and rubber fender system On the purpose of study is analyzed the plasticity dissipated energy of vessel and fender system. We blow characteristic that kinetic energy is disappeared by plastic large deformation in case of collision. Also, We considered dissipated kinetic energy considering friction effect.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.143-150
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• 2005

In this study, to evaluate the collision behaviors of the navigating vessel and the dolphin protective system protecting the substructures of bridges, the numerical simulation was performed. The analysis model of vessel bow that the plastic deformations are concentrated was composed by shell elements, and the main body of vessel was modeled by beam elements to represent the mass distribution and the change of potential energy. The material model reflecting the confining condition was used for the modeling of the filling soil of dolphin system. The surrounding soil of the dolphin system was modeled as nonlinear springs. As results, it is verified that the dolphin system can adequately dissipate the kinematic energy of the collision vessel. The surrounding soil of the dolphin system is able to resist the collision force of the vessel. And the major energy dissipation mechanism of collision energy is the plastic deformation of the vessel bow and the dolphin system.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.471-474
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• 2009

현대 사회는 유비쿼터스와 함께 Intelligent Bridge와 녹색 뉴딜개념의 Energy Birdge 같은 신개념의 교량연구에 주력하고 있다. 따라서 교량 안전관리는 무선 센서노드로 데이터를 송신하고 있으나 센서 전력에 수명제한 베터리와 기후제한 태양열로 공급 문제가 있다. 이에 본 논문에서는 외력에 의해 bending vibration이 일어나면서 판 양면에 양 음의 전하가 띄어 전압, 전류가 발생하는 압전소자를 이용 하였다. 이 압전소자에 발생하는 정현파로 인한 축전 문제와 발전된 전력이 다른 압전소자에게 흘러 전력생산량의 감소 문제는 Bridge Diode를 사용한 R-C회로도를 구성하여 보완하였다. 이 설계를 통하여 차량 하중(외력)의 크기에 변수를 두어 전압발생 차이를 측정하고 일정시간 외력 통해 Capacitor 축전된 양을 검토하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.311-314
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• 2007

The experimental method of measuring dynamic properties of structures was presented. The method is based on the flexural wave propagation characteristics. Using the method, change in structural dynamic properties due to damage is measured. The crack has much more significant impact on the strain energy than the inertial effects. From this, the sensitivity of the dynamic stiffness on the crack location is estimated by calculating the strain energy. When the wave propagates, the strain and kinetic energies shows cyclic changed over space. The crack that occurred at locations where the wave energy is in the form of the potential energy affected most significantly the wave propagation characteristics. The effects of crack location on the wave propagation were used to determine the crack location.

• Structural Engineering and Mechanics
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• v.10 no.1
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• pp.37-51
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• 2000

Identification of damage location based on modal measurement is an important problem in structural health monitoring. The damage index method that attempts to evaluate the changes in modal strain energy distribution has been found to be effective under certain circumstances. In this paper two damage index methods using bending strain energy and shear strain energy have been evaluated for numerous cases at different locations and degrees of damage. The objective is to evaluate the feasibility of the damage index method to localize the damage on large span concrete bridge. Finite element models were used as the test structures. Finally this method was used to predict the damage location in an actual structure, using the results of a modal survey from a large concrete bridge.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.6
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• pp.406-413
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• 2015

The piezoelectric coupling in piezoelectric vibration energy harvesters with load resistance induces electrical damping as well as increase in the system stiffness. Starting from analytically deriving the explicit relations through governing equations in the frequency domain, this work identifies the characteristics of the electrically induced damping mechanism and shows that the electrically induced damping serves as a structural hysteretic damping on condition that a piezoelectric vibration energy harvester is excited at its short-circuit resonant frequency and its load resistor is optimally impedance- matched at the same time. Finally, it is analytically verified that the equivalence of a mechanical and an electrically induced damping ratio is required for the maximum power generation at a load resistor, which was claimed in some literature.