• Earthquakes and Structures
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• v.10 no.5
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• pp.989-1012
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• 2016

The structural dynamic behavior and yield strength considering both ductility and strain rate effects are analyzed in this article. For the single-degree-of-freedom (SDOF) system, the relationship between the relative velocity and the strain rate response is deduced and the strain rate spectrum is presented. The ductility factor can be incorporated into the strain rate spectrum conveniently based on the constant-ductility velocity response spectrum. With the application of strain rate spectrum, it is convenient to consider the ductility and strain rate effects in engineering practice. The modal combination method, i.e., square root of the sum of the squares (SRSS) method, is employed to calculate the maximum strain rate of the elastoplastic multiple-degree-of-freedom (MDOF) system under uniform excitation. Considering the spatially varying ground motions, a new response spectrum method is developed by incorporating the ductility factor and strain rate into the conventional response spectrum method. In order to further analyze the effects of strain rate and ductility on structural dynamic behavior and yield strength, the cantilever beam (one-dimensional) and the triangular element (two-dimensional) are taken as numerical examples to calculate their seismic responses in time domain. Numerical results show that the permanent displacements with and without considering the strain rate effect are significantly different from each other. It is not only necessary in theory but also significant in engineering practice to take the ductility and strain rate effects into consideration.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1217-1222
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• 2004

This paper describes the development of tele-robotic interface for the hot-line maintenance robot system. One of main issues in designing human-robot interface for the hot-line maintenance robot system is to plan the control procedure for each part of the robotic system. Another issue is that the actual degree of freedom (DOF) in the hot-line maintenance robot system is much greater than that of available control devices such as joysticks and gloves in the remote-cabin. For this purpose, a virtual simulator, which includes the virtual hot-line maintenance robot system and the environment, is developed in the 3D environment using CAD data. It is assumed that the control operation is done in the remote cabin and the overall work process is observed using the main-camera with 2 DOFs. For the input device, two joysticks, one pedal, two data gloves, and a Head Mounted Display (HMD) with tracker sensor were used. The interface is developed for each control mode. Designed human-interface system is operated using high-level control commands which are intuitive and easy to understand without any special training.

• Structural Engineering and Mechanics
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• v.29 no.4
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• pp.433-453
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• 2008

The equation of motion of a one way (vertical) spanning strip wall, as an assembly of two rigid bodies, is presented. Only one degree of freedom is needed to completely describe the wall response as the bodies are assumed to be perfectly rectangular and are allowed to rock but not to slide horizontally. Furthermore, no arching action occurs since vertical motion of the upper body is not restrained. Consequently, the equation of motion is nonlinear, with non constant coefficients and a Coriolis acceleration term. Phenomena associated with overburden to self weight ratio, motion triggering, impulsive energy dissipation, amplitude dependency of damping and period of vibration, and scale effect are discussed, contributing to a more complete understanding of experimental observations and to an estimation of system parameters based on the wall characteristics, such as intermediate hinge height and energy damping, necessary to perform nonlinear time history analyses. A comparison to a simple standing, or parapet, wall is developed in order to better highlight the characteristics of this assembly.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1995.06a
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• pp.77-81
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• 1995

Video composition is to integrate multiple image materials into one scene. It considerably enhances the degree of freedom in producing various scenes. However, we need to adjust the viewing point sand the image planes of image planes of image materials for high quality video composition. In this paper, were propose an intelligent video composition technique concentrating on the composition of CG and real scene. We first model the camera system. The projection is assumed to be perspective and the camera motion is assumed to be 3D rotational and 3D translational. Then, we automatically extract camera parameters comprising the camera model from real scene by a dedicated algorithm. After that, CG scene is generated according to the camera parameters of the real scene. Finally the two are composed into one scene. Experimental results justify the validity of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.176.1-176
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• 2001

Conventional researches almost have been focused on the one dimensional inverted pendulum. Recently, Sprenger et al[2] have researched a two dimensional inverted pendulum Observing human's action to control an inverted pendulum, one can recognize that human uses a three dimensional metier including the up and down motion. In this paper, we propose a fuzzy logic controller(FLC) of a new three dimensional inverted pendulum system. We derive a dynamic equation of the mechanism including a 3-axis cartesian robot and a inverted pendulum. We propose a design method of a fuzzy controller of the yaw and pitch angles of a inverted pendulum. In the design, the redundant degree-of-freedom(DOF) of the robot ...

• Bulletin of the Society of Naval Architects of Korea
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• v.21 no.1
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• pp.13-20
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• 1984

As the first step to the dynamic stress analysis of structures, transient responses of a Timoshenko beam with variable section subject to impact load are analyzed. According to the various characteristics of impact load, time histories of the transient response of Timoshenko beam with general boundary conditions are obtained and compared with those of one degree of freedom system. Numerical solutions of the governing equations of motion are calculated by adopting the equivalent lumped-mass system and the finite difference method. It is found that the dynamic responses of Timshenko beam depend on the effect of concentration and location of impact load. As a result, increasing tendency of fluctuation in dynamic response, especially in bending moment, is found according to the increase of load concentration factor in time and space.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2171-2175
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• 2002

Helicopter dynamics are plenty of nonlinearity. A complete mathematical model including propeller dynamics and fortes generated by the propellers is very difficult to obtain. So the method used to design to design a controller is a parameter estimation. Design controller based on variable structure system. This paper deals with LQR control technique to control efficiently, its elevation angle and azimuth one. The purpose of the experiment is to design a controller allows to use a desired elevation angle and azimuth ones. The system model has a helicopter model with 2-degree-of freedom. The simulation results were verified usefulness of controller.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.11
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• pp.1272-1278
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• 2011

Mechanisms of the robot system should be developed according to the task. In this study, we propose improving adaptability of the robot mechanism with the modularized joint mechanism. Adaptability is the measure of the system ability to cope with change or uncertainty. Modular type joint has been widely used in development of various robots including reconfigurable robots. To build robotic systems more flexibly and quickly with low costs of manufacturing and maintenance, we have designed a modular type joint with one degree of freedom for general purpose. This module is designed to be compact, light-weight and self-controlled. In this design, we consider the kinematics and dynamics properties of the modular type joint.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.501-507
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• 2000

This paper presents a very simple procedure for determining the sensitivities of the eigenpairs of damped vibratory system with distinct eigenvalues. The eigenpairs derivatives can be obtained by solving algebraic equation with a symmetric coefficient matrix whose order is (n+1) ${\times}$ (n+1), where n is the number of degree of freedom the mothod is an improvement of recent work by I. W. Lee, D. O. Kim and G. H. Jung; the key idea is that the eigenvalue derivatives and the eigenvector derivatives are obtained at once via only one algebraic equation, instead of using two equations separately as like in Lee and Jung's method. Of course, the method preserves the advantages of Lee and Jung's method.

• Bulletin of the Korean Mathematical Society
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• v.36 no.1
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• pp.147-159
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• 1999

Tabanov investigated the global symmetric perturbation of the integrable billiard mapping in the ellipse [3]. He showed the nonintegrability of the Birkhoff billiard in the perturbed domain by proving that the principal separatrices splitting angle is not zero.In this paper, using the exact separatrix map of an one-degree-of freedom Hamiltoniam system with time periodic perturbation, we show the existence the stochastic layer including the uniformly hyperbolic invariant set which implies the nonintegrability near the separatrices of a Birkhoff's billiard in the domain bounded by $C^2$ convex simple curve constructed by the generic global perturbation of the ellipse.