• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.749-753
• /
• 2007

The purpose of this study is to design of a linear feeder using a multi body dynamic program, and to analyze a dynamic motion of the feeder that can transport small mechanical parts uniformly. In order to establish the analysis model of the linear feeder, each parts of the feeder are divided into two types which the rigid and flexible body. For the dynamic simulation, RecurDyn, which is a commercial multi-body dynamic package, is used. We also consider the design parameters for optimal dynamic motion such as centroid, stiffness, and mass of the feeder system. In order to analyze the dynamic motion of a linear feeder, the displacements of the feeder are measured by several accelerometers when it is in an operating condition. After the signal data from the accelerometers are captured in the time domain, the dynamic motion in the space is visualized by using graphic computer software.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2022.05a
• /
• pp.587-588
• /
• 2022

In this paper, we propose a rigid body tracking method in 3D space using 2D passive marker images from multiple motion capture cameras. First, a calibration process using a chess board is performed to obtain the internal variables of individual cameras, and in the second calibration process, the triangular structure with three markers is moved so that all cameras can observe it, and then the accumulated data for each frame is calculated. Correction and update of relative position information between cameras. After that, the three-dimensional coordinates of the three markers were restored through the process of converting the coordinate system of each camera into the 3D world coordinate system, the distance between each marker was calculated, and the difference with the actual distance was compared. As a result, an error within an average of 2mm was measured.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.1
• /
• pp.163-181
• /
• 1998

In this study, the objective is determine the optimal design variable of engine mount system using the rubber mount of bush-type which is usually utilized in passive control to minimize vibrations of vehicle body or transmission from engine into body. The engine model adopted in this study is 4-cylinder, 4-stroke gasoline engine support- ed by 4-points. The system is modelled in 10 d.o.f.-rigid body motion of the engine & transmission in 6 d.o.f., elastic motion of vehicle body in 4 d.o.f.(1st torsional, 1st vertical and 1st & 2nd lateral bending vibration mode). To consider the elastic motion of vehicle body, find the eigenvalues and mode shapes of vehicle body by nodal testing and then determine the modal masses and stiffnesses of the body. The design variables of the engine mount system are locations, stiffness and damping coefficients of the rubber mounts(28 design variables). In case of considering the torque-roll axis for the engine, the design variables of the mount system are reduced to 22 design variables. The objective functions in optimal design process are considered by three cases, that is, 1) transmitted forces through engine mounts, 2) acceleration components of generalized coordinates for the vibration of vehicle body, 3) acceleration of specified location(where gear box) of body. three case are analyzed and compared with each other.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.6 no.4
• /
• pp.1024-1040
• /
• 2014

The theoretical background and a numerical solution procedure for a time domain hydroelastic code are presented in this paper. The code combines a VOF-based free surface flow solver with a flexible body motion solver where the body linear elastic deformation is described by a modal superposition of dry mode shapes expressed in a local floating frame of reference. These mode shapes can be obtained from any finite element code. The floating frame undergoes a pseudo rigid-body motion which allows for a large rigid body translation and rotation and fully preserves the coupling with the local structural deformation. The formulation relies on the ability of the flow solver to provide the total fluid action on the body including e.g. the viscous forces, hydrostatic and hydrodynamic forces, slamming forces and the fluid damping. A numerical simulation of a flexible barge is provided and compared to experiments to show that the VOF-based flow solver has this ability and the code has the potential to predict the global hydroelastic responses accurately.

• Earthquakes and Structures
• /
• v.16 no.1
• /
• pp.109-118
• /
• 2019

This study, analyses the seismic response for a rigid massless square foundation resting on a viscoelastic soil layer limited by rigid bedrock. The foundation is subjected either to externally applied forces or to obliquely incident seismic body or surface harmonic seismic waves P, SV and SH. A 3-D frequency domain BEM formulation in conjunction with the thin layer method (TLM) is adapted here for the solution of elastodynamic problems and used for obtained the seismic response. The mathematical approach is based on the method of integral equations in the frequency domain using the formalism of Green's functions (Kausel and Peck 1982) for layered soil, the impedance functions are calculated by the compatibility condition. In this study, The key step is the characterization of the soil-foundation interaction with the input motion matrix. For each frequency the impedance matrix connects the applied forces to the resulting displacement, and the input motion matrix connects the displacement vector of the foundation to amplitudes of the free field motion. This approach has been applied to analyze the effect of soil-structure interaction on the seismic response of the foundation resting on a viscoelastic soil layer limited by rigid bedrock.

• Journal of applied mathematics & informatics
• /
• v.14 no.1_2
• /
• pp.251-266
• /
• 2004

We consider a controlled nonlinear mechanical system described by the Lagrange equations. We determine the control forces $Q_1$ and the restrictions for the perturbations $Q_2$ acting on the mechanical system which allow to guarantee the asymptotic stability of the program motion of the system. We solve the problem of stabilization by the direct Lyapunov's method and the method of limiting functions and systems. In this case we can use the Lyapunov's functions having nonpositive derivatives. The following examples are considered: stabilization of program motions of mathematical pendulum with moving point of suspension and stabilization of program motions of rigid body with fixed point.

• Journal of KSNVE
• /
• v.7 no.2
• /
• pp.261-272
• /
• 1997

Recently washing machines are to be in lower vibration and lower sound because of better environment. Vibration problems in washing machines occur in both washing mode and spinning mode, but vibration in spinning mode becomes main problem because of its high rotating speed and continuity. Vibration while spinning is mainly due to rigid body motion of total washing system which includes suspending rods, washing bath, spinning bath, and gear sets. In this study, some researches were done in order to analyze the rigid body motion of washing system and flexible vibration of spinning bath. A basic mathematical model was established, and the effect of position of salt water and shape change of salt water case were considered. And the effect of lengths of suspending rods, attaching angles, vertical and horizontal position, stiffness of spring on the change of vibration were also considered. To identify the effect of salt water on vibration, some measurements were done. When salt water was positioned at upper part, the effect was most and this coincides with the tendency of simulation.

• 제어로봇시스템학회:학술대회논문집
• /
• 1994.10a
• /
• pp.213-217
• /
• 1994

The attitude stability of a satellite in spin-stabilized injection mode which contains a liquid pool is investigated. The satellite model for investigation is a two-body system consisting of a the main body, which is symmetric and rigid, representing the spacecraft, and a spherical pendulum, representing the liquid pool. Assuming that both spacecraft and pendulum are in states of steady spin about the symmetry axis of the spacecraft, the coupled nonlinear equations of motion for the system are simplified. In this paper, by using the multiple scales method, the possible resonance conditions in terms of the system parameters are determined and the corresponding near-resonant solutions are derived.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11a
• /
• pp.85-89
• /
• 2001

Hamiltonian modeling approach has been extensively adopted for rigid body dynamics whereas its usage for deforming flexible continuum dynamics has been limited. A set of Hamilton＇s equations for flexible body motion with finite deformation has been derived and applied for a nonlinear impact problem.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.1360-1365
• /
• 2007

A linear compressor used in a refrigerator has higher energy efficiency than other compressors. On the other hand, its vibration level has still been much severe. Changing the characteristics of connecting parts may reduce the vibration level of linear compressor. The piston, body and shell are assumed to be rigid. These rigid bodies are connected by coil springs and flexible loop pipe. This paper derived the mathematical model by combining the equation of motion of rigid parts and flexible parts. The variation of vibration level according to the change of connecting parts was investigated.