• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.12 no.1
• /
• pp.57-64
• /
• 2002

Three kinds of viscoelastic damper model, which has a non-linear spring as an element is studied analytically and numerically The behavior of the damper model shows non-linear hysteresis curves which is qualitatively similar to those of real viscoelastic materials. The motion is governed by a non-linear constitutive equation and an additional equation of motion. Harmonic balance method is applied to get analytical solutions of the system. The frequency-response curves sallow that multiple solutions co-exist and that the jump phenomena can occur. In addition, it is shown that separate solution branch exists and that it can merge with the primary response curve. Saddle-node bifurcation sets explain the occurrences of such non-linear Phenomena.

• Journal of Auto-vehicle Safety Association
• /
• v.5 no.1
• /
• pp.25-30
• /
• 2013

The main purpose of this research is to predict dynamic behavior of door locking system for side impact safety and the design process to avoid door opening is introduced. The equations of motion that represent the system are obtained from the energy equation. From them, the motion of door handle is predicted by using Runge-Kutta $4^{th}$ order method and the simulation result is compared with the real crash data. Also, the design guide to define the properties of door locking system from the standpoint of avoiding door opening phenomenon is introduced.

• Journal of Advanced Marine Engineering and Technology
• /
• v.34 no.7
• /
• pp.997-1008
• /
• 2010

The mooring line tension and motion response of a floating fish reef system were analyzed using a Morison equation type numerical model. The reef structure was constructed with pipe and suspended up from the bottom with a single, high tension mooring. Input forcing parameters into the model consisted of both regular and random waves, with and without currents. Heave, surge and pitch dynamic calculations were made, along with the tension response in the mooring lines. Results were analyzed in both the time and frequency domains and where appropriate, linear transfer functions were calculated. In addition, damped and natural periods of the system were determined to examine a resonating situation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.304-309
• /
• 2003

A new modal analysis method for rotor systems with periodically time-varying parameters is proposed. The essence of method is to introduce modulated coordinates to derive the equivalent time-invariant equation. This paper presents a modal analysis method using modulated coordinates fur general rotors, of which rotating and stationary parts both possess asymmetric properties. The equation of motion with time-varying parameters is transformed to an infinite order matrix equation with the time-invariant parameters. A theory of modal analysis for the system is presented with the infinite order equation and a couple of reduced order equations. A numerical example with simple asymmetric rotor is provided to demonstrate the effectiveness of the proposed method

• International Journal of Precision Engineering and Manufacturing
• /
• v.3 no.4
• /
• pp.54-63
• /
• 2002

In recent years, mechanical systems such as high speed vehicles and railway trains moving on elastic beam structures have become a very important issue to consider. In this paper, a general approach, which can predict the dynamic behavior of a constrained mechanical system moving on a flexible beam structure, is proposed. Various supporting conditions for the foundation support are considered for the elastic beam structure. The elastic structure is assumed to be a non-uniform and linear Bernoulli-Euler beam with a proportional damping effect. Combined differential-algebraic equation of motion is derived using the multi-body dynamics theory and the finite element method. The proposed equations of motion can be solved numerically using the generalized coordinate partitioning method and predictor-corrector algorithm, which is an implicit multi-step integration method.

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.745-747
• /
• 2001

This paper deals with the dynamic characteristics of flat core LOA. The LOA system was represented by the voltage equation of coil and the mechanical equation of motion. Also, driving system was simply composed voltage source inverter and generates square-wave. It is measured that dynamic characteristic vary as square-wave.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.399-402
• /
• 1999

This study is about seismic performance of the EDF(Electricite De France) system, that is among various base isolator. We get solutions of equation of motion of this system for displacement, velocity, acceleration and compared with solutions using finite element program. And, through shaking table tests we will prove seismic performance

• International Journal of Precision Engineering and Manufacturing
• /
• v.2 no.4
• /
• pp.30-39
• /
• 2001

This paper investigates vibrational motion of a flexible beam fixed on a moving cart and carrying a moving mass. The equations of motion of the beam-mass-cart system are analysed through the unconstrained modal analysis. The exact normal mode solution used in modal analysis correspond to the eigenfrequencies for each position of the moving mass and to the ratios of the weight of the beam-mass-car system. Time solutions of normal modes are also transformed properly according to the position of the moving mass. Numerical simulations are carried out to obtain open-loop responses of the system in tracking pre-designed paths of the moving mass. The simulation results show that the model predicts the dynamic behavior of the beam-mass-cart system well. Experiments are carried out to show the validity of the proposed analytical method.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2002.10a
• /
• pp.142-148
• /
• 2002

Autonomous underwater vehicles (AUVs) are unmanned underwater vessels to investigate sea environments, oceanography and deep-sea resources autonomously. Docking systems are required to increase the capability of the AUVs to recharge the batteries and to transmit data in real time for specific underwater works, such as repeated jobs at sea bed. This paper presents a visual servo control system for an AUV to dock into an underwater station with a camera mounted at the nose center of the AUV. To make the visual servo control system, this paper derives an optical flow model of a camera, where the projected motions of the image plane are described with the rotational and translational velocities of the AUV. This paper combines the optical flow equation of the camera with the AUVs equation of motion, and derives a state equation for the visual servoing AUV. This paper proposes a discrete-time MIMO controller minimizing a cost function. The control inputs of the AUV are automatically generated with the projected target position on the CCD plane of the camera and with the AUVs motion. To demonstrate the effectiveness of the modeling and the control law of the visual servoing AUV, simulations on docking the AUV to a target station are performed with the 6-dof nonlinear equations of REMUS AUV and a CCD camera.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.2
• /
• pp.174-180
• /
• 2004

Failure of tube bundles due to excessive flow-induced vibrations continues to affect the performance of nuclear power plant Early experimental studies concentrated on rigid structures and later investigators dealt with elastic structures because of their importance in many engineering fields. On the other hand, much less numerical work has been carried out, because of the numerical complexity associated with the problem. Conventional approaches usually decoupled the flow solution from the structural problem. The present numerical study proposes the methodology in analyzing the fluidelastic instability occurring in tube bundles by coupling the Computational fluid Dynamics (C%) with the tube equation of motions. The motion of the structures is modeled by a spring-damper-mass system that allows transnational motion in two directions (a two-degree-of-freedom system). The fluid motion and the cylinder response are solved in an iterative way, so that the interaction between the fluid and the structure can be accounted for property. The aim of the present work is to predict the fluidelstic instability of tube bundles and the associated phenomena, such as the response of the cylinder, the unsteady lift and drag on the cylinder, the vortex shedding frequency.