• International Journal of Aeronautical and Space Sciences
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• v.2 no.1
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• pp.78-92
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• 2001

In this paper, several dynamic systems are modeled using the time domain finite element method. Galerkins' Weak Principle is used to model the general second-order mechanical system, and is applied to a simple pendulum dynamics. Problems caused by approximating the final momentum are also investigated. Extending the research, some dynamic analysis methods are suggested for the hybrid coordinate systems that have both slew and flexible modes. The proposed methods are based on both Extended Hamilton's Principle and Galerkin's Weak Principle. The matrix wave equation is propagated in space domain, satisfying the geometric/natural boundary conditions. As a result, the flexible motion can be obtained compatible with the applied control input. Numerical example is shown to demonstrate the effectiveness of the proposed modeling methods for the hybrid coordinate systems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.643-647
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• 1996

The dynamic behavior of hydrostatic table is represented as the theoretical model, 1-dof, 2-dof rigid body spring-damper system, and finite element model. By the experimental and theoretical methods, the validity of these models and some other dynamic behaviors, such as the effects of unbalanced load and three dimensional motion, are investigated. To make easier to consider the dynamic behavior of hydrostatic table in design process, the stiffness and damping coefficients are calculated using the simple approximation method delived from the mass flow continuity condition, and compared with experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.108-113
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• 1999

For cylindrical shells, the closed-form solutions are confined to the specific boundary and/or loading conditions. Though the finite element method is certainly a powerful solution approach for the structural dynamics problems, it has been well known to provide the solution reliable only in the low frequency region due to the inherent high sensitivities of structual and numerical modeling errors. Instead, the spectral element method has been proved to provide accurate dynamic characteristics of a structure even at the ultrasonic frequency region. Since the wave characteristic of a cylindrical shell becomes identical to that fo a flat plate as the frequency increases, an equivalent plate model (EPM) representing the high-frequency dynamic characteristics of the cylindrical shell is introduced herein. The EPM-based spectral element analysis solutions are compared with the known analytical solutions for the cylindrical shells to confirm the validity of the present modeling approach.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.495-505
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• 2008

This paper describes modeling Voltage Sourced Inverter (VSI) type Flexible AC Transmission System (FACTS) controllers and control methods for power system dynamic stability studies. The considered FACTS controllers are the Static Compensator (STATCOM), the Static Synchronous Series Compensator (SSSC), and the Unified Power Flow Controller (UPFC). In this paper, these FACTS controllers are derived in the current injection model, and it is applied to the linear and nonlinear analysis algorithm for power system dynamics studies. The parameters of the FACTS controllers are set to damp the inter-area oscillations, and the supplementary damping controllers and its control schemes are proposed to increase damping abilities of the FACTS controllers. For these works, the linear analysis for each FACTS controller with or without damping controller is executed, and the dynamic characteristics of each FACTS controller are analyzed. The results are verified by the nonlinear analysis using the time-domain simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.2
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• pp.158-166
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• 2002

A mathematical model and dynamic characteristics ova continuously variable damper for semi-active suspen- sion systems are investigated. After analyzing the geometry of a typical continuously variable damper, mathematical models fur individual components including piston, orifices, spring, and valves are first derived and then the flow equations for extension and compression strokes are investigated. To verify the developed mathematical model, the dynamic response of the model are simulated using MATLAB/SIMULINK and are compared with experimental results. The proposed model can be used not only for mechanical components design but also for control system design.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.183-190
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• 1999

In this paper, a dynamic modeling approach is introduced to identify the dynamic characteristics of the structural/mechanical joints within an one-dimensional structure. A structural joint is represented by the four-pole parameters and the four-pole parameters are determined from the measured frequency response functions by using the spectral element method. As the illustrative examples, a cantilevered beam a clamped-clamped beam, both consist of two beams connected by a bolted joint, are investigated to evaluate the present modeling approach. It is found that the dynamic responses predicted by using the identified for-pole parameters for the bolted joint are well agreed with the measured dynamic responses measured

• The Pure and Applied Mathematics
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• v.29 no.2
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• pp.141-160
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• 2022

From the past until now, political and economic relations among countries have been one of the most important issues among analysts and numerous studies have tried to analyze these relations from different theoretical perspectives. The dynamic system of games has introduced a new modeling method in the game theory. In this study, we use behavioral models (level- k) along with the dynamic system in games to model rational agent behavior. As an application, we study Russia- Norway economic and political relations (1970-2019). The dynamic system in games along with behavioral games theory can be used to predict the players behavior in the future.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.853-854
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.156-159
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• 2008

Proper orthogonal decomposition is a statistical pattern analysis technique for finding the dominant components, called the proper orthogonal modes, in ensembles of spatially distributed data. We present recent ideas based on proper orthogonal decomposition (POD) and detailed experiments that yield new perspectives into the microscale structures. The linearized modeling technique based on POD is very useful to show the principal characteristics of the complex dynamic responses.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.842-846
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• 1996

Leaf springs are widely used as a major suspension component in many commercial vehicles, such as buses, trucks, etc. They have a complex dynamic behavior due to the geometric nonlinear and the contact mechanism between the leaves. The interface conditions between the leaves play a significant role in the global behavior of the comfort and ride of the vehicle system. The paper concentrates on modeling leaf springs and contact frictions between the leaves using a nonlinear finite element approach. A nonlinear load-displacement hysteresis curve for the leaf spring is simulated and its results are compared with test results.