• Proceedings of the IEEK Conference
• /
• 2002.07b
• /
• pp.1216-1219
• /
• 2002

It is understood so far that the center of mass does not make any linear movement from the rotatory movement of a rigid body in the closed system. However, it has been found that the center of mass of the system could make a closed linear movement due to production of an instantaneous center of mass by the Coriolis force in the rotatory movement of a rigid body in the closed system. The nature of the closed linear movement in the non-inertial system and that of the open movement in the inertial system are different from each other. That is, the closed movement is described like the time integration of frictional forces, which is different from the open movement usually considered and described like the time integration of external forces. It is shown in this paper that the Coriolis forces, called a fictitious force in the classical mechanics, is similar to the frictional force so that it causes to move the center of mass of a closed system. In this paper, following an explanation of the closed linear movement of a non-inertial system and the open movement of an inertial system, the source of the closed linear movement phenomenon of a rotatory rigid body is presented.

• Structural Engineering and Mechanics
• /
• v.58 no.6
• /
• pp.1127-1143
• /
• 2016

The pounding phenomenon in adjacent structures happens in severing earthquakes that can cause great damages. Connecting neighboring structures with active and semi-active control devices is an effective method to avoid mutual colliding between neighboring buildings. One of the most important issues in control systems is applying online control force. There will be a time delay if the prose of producing control force does not perform on time. This paper proposed a time-delay compensation method in coupled structures control, with semi-active Magnetorheological (MR) damper. This method based on Newmark's integration is adopted to mitigate the time-delay effect. In this study, Lyapunov's direct approach is employed to compute demanded voltage for MR dampers. Using Lyapunov's direct algorithm guarantees the system stability to design a controller based on feedback. Because of the strong nonlinearity of MR dampers, the equation of motion of coupled structures becomes an involved equation, and it is impossible to solve it with the common time step methods. In present paper modified Newmark-Beta integration based on the instantaneous optimal control algorithm, used to solve the involved equation. In this method, the response of a coupled system estimated base on optimal control force. Two MDOF structures with different degrees of freedom are finally considered as a numeric example. The numerical results show, the Newmark compensation is an efficient method to decrease the negative effect of time delay in coupled systems; furthermore, instantaneous optimal control algorithm can estimate the response of structures suitable.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.4
• /
• pp.365-373
• /
• 2011

This paper presents the dynamic response and the vibration characteristics for a rail-track supported by discrete springs and dampers. Recently, automatic conveyer system, rail-track, rack-master system demand the soundproof facilities and vibration suppression measures in order to satisfy the strict environmental standards. The equations of motions of the dynamic characteristics for a vibration suppression rail-track under a traveling mass were derived by Galerkin's mode summation method considering gravity, centrifugal force, Coriolis force, inertia force of the moving mass, transverse inertia of the rail-track. Also, numerical results were calculated by Runge-Kutta integration method. In order to investigate vibration characteristics and dynamic responses, modal testing and measurement of the responses of the rail-track were performed. Through the experiment and numerical simulations, numerical results have a good agreement with experimental ones.

• Smart Structures and Systems
• /
• v.14 no.6
• /
• pp.1269-1289
• /
• 2014

With the sub-stepping technique, the numerical analysis in real-time dynamic hybrid testing is split into the response analysis and signal generation tasks. Two target computers that operate in real-time may be assigned to implement these two tasks, respectively, for fully extending the simulation scale of the numerical substructure. In this case, the integration time-step of solving the dynamic response of the numerical substructure can be dozens of times bigger than the sampling time-step of the controller. The time delay between the real and desired feedback forces becomes more striking, which challenges the well-developed delay compensation methods in real-time dynamic hybrid testing. This paper focuses on displacement prediction and force correction for delay compensation in the real-time dynamic hybrid testing with a large integration time-step. A new displacement prediction scheme is proposed based on recently-developed explicit integration algorithms and compared with several commonly-used prediction procedures. The evaluation of its prediction accuracy is carried out theoretically, numerically and experimentally. Results indicate that the accuracy and effectiveness of the proposed prediction method are of significance.

• Journal of Mechanical Science and Technology
• /
• v.19 no.spc1
• /
• pp.429-436
• /
• 2005

This paper presents a precise and stable time integration method for dynamic analysis of vibration or multibody systems. A total system is divided into several subsystems and their responses are calculated separately, while the coupling effect is treated equivalently as constant force during time steps. By using iterative procedure to improve equivalent coupling forces, a precise and stable solution is obtained. Some examples such as a seismic response and multibody analyses were carried out to demonstrate its usefulness.

• Journal of Information Technology and Architecture
• /
• v.9 no.1
• /
• pp.111-120
• /
• 2012

Many Countries are recently focued on building capability based military and operating for the defense budget efficiency and operational effectiveness. The EA not only defines enterprise scope but also identifies relation among them, manage change and complexity. Accordingly, this research aims to build architecture framework which can achieve alignment, integration and interoperability by developing it with output. Through this, architecture framework can be changed into force development and operation. And it can be used for construction of effective force and operation for NCO by applying mathematical model and method of force priority development based on developed capabilities-based architecture framework.

• Journal of the Korean Society for Precision Engineering
• /
• v.14 no.3
• /
• pp.57-65
• /
• 1997

In this study, a cutting force in the Ball-end milling process is calculated using Z-map. Z-map can describe any type of cutting area resulting from the previous cutting geometry and cutting condition. Cutting edge of a ball-end mill is divided into infinitesimal cutting edge elements and the position of the ele- ment is projected to the cutter plane normal to the Z axis. Also the cutting area in the cutter plane is obtained by using the Z-map. Comparing this projected position with cutting area, it can be determined whether it engages in the cutting. The cutting force can be calculated by numerical integration of cutting force acting on the engaged cutting edge elements. A series of experiments such as contouring and upward/downward ramp cutting was performed to verify the calculated cutting force.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.251-255
• /
• 2003

This paper presents the design, fabrication, and calibration of a piezoelectric polymer-based sensorized microgripper. Electro discharge machining technology is employed to fabricate super-elastic alloy based micro gripper. It is tested to present improvement of mechanical performance. For integration of force sensor on the micro gripper, the sensor design based on the piezoelectric polymer PVDF film and fabrication process are presented. The calibration and performance test of force sensor integrated micro gripper are experimentally carried out. The force sensor integrated micro gripper is applied to perform fine alignment tasks of micro opto-electrical components. It successfully supplies force feedback to the operator through the haptic device and plays a main role in preventing damage of assembly parts by adjusting the teaching command.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.10
• /
• pp.1772-1777
• /
• 2003

This paper presents the design, fabrication, and calibration of a piezoelectric polymer-based sensorized microgripper. Electro discharge machining technology is employed to fabricate super-elastic alloy based micro gripper. It is tested to present improvement of mechanical performance. For integration of force sensor on the micro gripper, the sensor design based on the piezoelectric polymer PVDF film and fabrication process are presented. The calibration and performance test of force sensor integrated micro gripper are experimentally carried out. The force sensor integrated micro gripper is applied to perform fme alignment tasks of micro opto-electrical components. It successfully supplies force feedback to the operator through the haptic device and plays a main role in preventing damage of assembly parts by adjusting the teaching command.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.04a
• /
• pp.125-129
• /
• 1996

In this study, a method is proposed for the cutting force prediction of Ball-end milling process using Z-map is proposed. Any types of cutting area generated from previous cutting process can be expressed in z-map data. Cutting edge of a ball-end mill is divided into a set of finite cutting edges and the position of this edge is projected to the cross-section plane normal to the Z-axis. Comparing this projected position with Z-map data of cutting area and determining whether it is in the cutting region, total cutting force can be calculated by means of numerical integration. A series of experiments such as side cutting and upward/downard cutting was performet to verify the simulated cutting force.