• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.486-489
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• 2006

This paper presents a newly proposed object-oriented finite element framework and its applications on dynamic analysis of plate girder bridge. The developed framework supports various types of finite elements, materials, constraints, loads, and solution methods. One major feature different from other object-oriented finite element programs is that static model and dynamic state can be easily read from or written to a file. In addition, the framework supports efficient DOF pattern handling for a node connecting elements with different DOF patterns, new multi-point constraint handling, and various scripting languages for easy use of the library. In order to show the applicability to dynamic analysis, dynamic moving load analysis on plate girder bridge is performed.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.64-69
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• 2002

In this study, the optimal dynamic isolation system for gas operated combat weapon has been investigated. For this purpose, firstly, the dynamic behavior of human induced by firing operations has been analyzed through a series of experimental works using the devised test setup. The characteristics of linear impulse has been compared under some conditions of support system. In order to design the optimal dynamic isolation system, parameter optimization process has been performed based on the simplified isolation system under constraints of moving displacement and transmitted force. Finally, the performance of the designed dynamic absorbing system has been evaluated by simulation.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.644-647
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• 1987

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.1
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• pp.1-13
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• 2001

In this paper, we propose a new dynamic bandwidth allocation and call admission control for VBR video sources with QoS constraints to support an efficient resource management and at the same Lime to satisfy the user's quality or service requirements. For the dynamic bandwidth allocation, first the next amount of traffic is predicted using a modified adaptive linear prediction method that considers abrupt scene change effects. And then, we dynamically allocate the necessary bandwidth to each connection based on the currently provided quality degree by the network with respect to the user's QoS requirements in terms of average delay and loss ratio. For the admission control, we determine the acceptance or rejection or a new connection based on the quality satisfaction degrees of the existing connections. Simulation results show that our proposed dynamic schemes are able to provide a stable service, which well meets the user's quality requirements.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.6
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• pp.737-742
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• 2011

Navigation problems include the task of determining the control input under various constraints for systems such as mobile robots subject to uncertain disturbance. Such tasks can be modeled as constrained stochastic control problems. In order to solve these control problems, one may try to utilize the dynamic programming(DP) methods which rely on the concept of optimal value function. However, in most real-world problems, this trial would give us many difficulties; for examples, the exact system model may not be known; the computation of the optimal control policy may be impossible; and/or a huge amount of computing resource may be in need. As a strategy to overcome the difficulties of DP, one can utilize ADP(approximate dynamic programming) methods, which find suboptimal control policies resorting to approximate value functions. In this paper, we apply recently proposed ADP methods to a class of navigation problems having complex constraints, and observe the resultant performance characteristics.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.3
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• pp.386-393
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• 2012

Portfolio selection methods based on stochastic receding horizon approach, which were recently reported in the field of financial engineering, can explicitly consider the dynamic characteristics of wealth evolution and various constraints in the process of performing optimal portfolio selection. In view of the theoretical value, versatility, and effectiveness that receding horizon approach has achieved in many engineering problems, dynamic portfolio selection methods based on stochastic receding horizon optimization technique have the possibility of becoming an important breakthrough. This paper observes through theoretical investigations that the SDP(semi-definite program)-based portfolio selection procedure can be simplified, and has obtained meaningful performance on returns from simulation studies applying the simplified version to Korean financial markets.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.125-133
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• 1993

Most studies on the vibration analysis of a beam-column with ends elastically restrained and various intermediate constraints have been based on the Euler beam theory, which is inadequate for beam-columns of low slenderness ratios. In this paper, analytical methods for vibration and dynamic sensitivity of a Timoshenko beam-column with ends elastically restrained and various intermediate constraints are presented. Firstly, an exact solution method is shown. Since the exact method requires considerable computational effort, a Rayleigh-Ritz analysis is also investigated. In the latter two kinds of trial functions are examined for comparisions : eigenfunctions of the base system(the system without intermediate constraints) and polynomials having properties corresponding to the eigenfunctions of the base system. The results of some numerical Investigations show that the Rayleigh-Ritz analysis using the characteristic polynomials is competitive with the exact solutions in accuracy, and that it is much more efficient in computations than using the eigenfunctions of the base system, especially in the dynamic sensitivity analysis. In addition, the prediction of the changes of natural frequencies due to the changes of design variables based on the first order sensitivity is in good agreements with that by the ordinary reanalysis as long as the changes of design variables are moderate.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.818-823
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• 2011

6-generalized coordinates of absolute translational displacements and angular displacements measured at Cartesian coordinates system fixed at the ground has been used to describe general dynamic behavior of a rigid body in mechanical systems. However, track coordinates system moving with the centerline of the track can be used to develop dynamic formulations for railway vehicle. It is easy to impose the constraints of track coordinates by the virtue of track coordinates system moving with track centerline. In this analysis, dynamic equations of railway vehicle by using track coordinates system is derived and the simulation results are presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.436-439
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• 2005

Dynamic contact of a cantilever beam with Sap at the end is discussed. The gap in a structure induces dynamic contact, and the contact problem is always accompanied by inequality constraints which mean that the solution of the structure with contact condition should satisfy variational inequality. Inequality, but, can be reduced to equality condition considering convex penalty function. In this paper, formulation of a beam with contact is derived using quasi convex penalty function. General coordinate solution which is needed to increase computational efficiency is applied. Nonlinear behavior of a beam with rigid and elastic contact condition was discussed.

• Journal of Information Processing Systems
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• v.14 no.2
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• pp.455-468
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• 2018

The concepts of graph theory are applied to model and analyze dynamics of computer networks, biochemical networks and, semantics of social networks. The analysis of dynamics of complex networks is important in order to determine the stability and performance of networked systems. The analysis of non-stationary and nonlinear complex networks requires the applications of ordinary differential equations (ODE). However, the process of resolving input excitation to the dynamic non-stationary networks is difficult without involving external functions. This paper proposes an analytical formulation for generating solutions of nonlinear network ODE systems with functional decomposition. Furthermore, the input excitations are analytically resolved in linearized dynamic networks. The stability condition of dynamic networks is determined. The proposed analytical framework is generalized in nature and does not require any domain or range constraints.