• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.489-494
• /
• 2002

This paper presents hydraulic model which can capture the hysteric damping force behavior of ER damper. A flow mode rue ER damper is manufactured, and its field-dependent damping forces are measured. Newly proposed hydraulic model which derived from physical hydro-mechanical parameters of ER damper are conventional Bingham model are investigated to represent the field-dependent damping force characteristics of ER damper. After principal parameters of two models are estimated from the measured damping forces data, the force vs velocity hysteresis cycles are then reconstructed. The results show that the proposed hydraulic model can capture the hysteresis behavior of ER damper accurately.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.12 no.9
• /
• pp.731-737
• /
• 2002

Nonlinear vibration of the CRT shadow mask with impact damping wires is analyzed in consideration of the mask tension distribution and the effect of wire impact damping. A reduced order FEM model of the shadow mask is obtained from dynamic condensation of the mass and stiffness matrices, and damping wire is modeled using the lumped parameter method to effectively describe its contact interactions with the shadow mask. The nonlinear contact-impact model is composed of spring and damper elements, of which parameters are determined from the Hertzian contact theory and the restitution coefficient, respectively. The analysis model of the shadow mask with damping wires is experimentally verified through impact tests of shadow masks performed in a vacuum chamber.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.11 s.116
• /
• pp.1140-1148
• /
• 2006

In this paper, transmission loss of smart panel was investigated using piezoelectric shunt damping. Admittance of piezoelectric system was introduced to represent electro-mechanical coupling of smart panel and to predict the performance of shunt damping. Finite element method was used to obtain numerical admittance. In order to illuminate the effect of noise reduction in the shunt system, transmission loss of the smart panel was investigated. Two models were considered to show the relation between admittance and transmission loss of smart panel. It was observed that admittance of piezoelectric system could be used as a design index of smart panel.

• Proceedings of the KSME Conference
• /
• 2000.11a
• /
• pp.576-583
• /
• 2000

A robust position control using a sliding mode controller is adopted for the stable dynamic walking of the biped. For the biped robot that is modeled with 14 degrees of freedom rigid bodies using the method of the multibody dynamics, the joint angles for simulation are obtained by the velocity transformation matrix using the given Cartesian foot and trunk trajectories. Hertz force model and Hysteresis damping element which is used in explanation of the energy dissipation during contact with ground are used for modeling of the ground reactions during the simulation. By the obtained that forces which contains highly confused noise elements and the system modeling uncertainties of various kinds such as unmodeled dynamics and parameter inaccuracies, the biped system will be unstable. For that problems, we are adopting a nonlinear robust control using a sliding mode controller. Under the assumption that the esimation error on the unknown parameters is bounded by a given function, that controller provides a successful way to preserve stability and achieve good performance, despite the presence of strong modeling imprecisions or uncertainties.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.13 no.12
• /
• pp.903-910
• /
• 2003

A two-degree-of-freedom model is suggested to describe basic dynamical behaviors of the interaction between the pad and the disc of a disc brake system. Although a pad (and a disc) has many modes of vibration in practice, only one mode of each component Is considered. In this paper, a linear analysis is performed by means of the stability analysis to show various conditions for the system to become unstable, and is based on the assumption that the existence of limit cycle (this corresponds to an unstable equilibrium point inside the limit cycle) represents the squeal state of the disc brake system. The results of the stability analysis show that the damping of the disc is as much Important as that of the pad, whereas the damping of the pad only is considered In most practical situations.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.5
• /
• pp.137-146
• /
• 2001

A robust controller with the sliding mode is proposed for stable dynamic walking of the biped robot in this paper. For the robot system to be controlled, which is modeled as 14 DOF rigid bodies by the method of multi-body dynamics, the joint angle trajectories are determined by the velocity transformation matrix. Also Hertz force model and Hysteresis damping element are utilized for the ground reaction and impact forces during the contact with the ground. The biped robot system becomes unstable since those forces contain highly confused noise components and some discontinuity, and modeling uncertainties such as parameter inaccuracies. The sliding mode control is applied to solve above problems. Under the assumption of the bounded estimation errors on the unknown parameters, the proposed controller provides a successful way to achieve the stability and good performance in spite of the presence of modeling imprecisions of uncertainties.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1994.04a
• /
• pp.59-64
• /
• 1994

본 논문에서는 다중 유리창의 STL값을 예측하는 방법에 대해 연구하였다. 유리창의 크기는 무한하다고 가정하였으며 음향 4단자방법을 이용하였으나 기존의 모델과는 달리 음파의 입사는 오나전한 확산음장이 아닌 각도에 따른 변화가 있다고 가정하였으며 또한 지지부의 댐핑도 고려하였다. 본 연구에서 제시된 방법을 사용하여 이중 및 삼중창의 여러가지 경우에 대해 계측치와 비교하였다. 본 방법은 유리가 아닌 강판, 석고보다 등 일반적인 탄성체와 흡음재가 배열된 경우에도 적용이 가능하나 여러 계측치와의 비교를 통해 문제점 및 응용성에 대해서 언급하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1992.04a
• /
• pp.227-231
• /
• 1992

본 연구에서는 ER(electro-rheological) 유체을 이용한 가변댐퍼(variable damper)를 제안했다. 전기장(electric field) 부하시 Bingham특성을 갖는 ER유체는 전기장에따라 항복전단응력이 변하기 때문에이를 이용하여 댐핑력을 제어할 수 있다. 피스톤의 상하압력차가 전기장의 함수이기 때문에 기존의 비능동 혹은 능동형 댐퍼에서 필요로하는 복잡한 밸브시스템이 필요없으며, 따라서 구조면에서 매우 간단하게 설계될 수 있고, 반응시간 또한 매우 빠르다. 간단한 현가정치 모델을 설정 하여제안된 ER 댐퍼의 효율성과 우수성을 주파수 및 시간 영역에서 해석하였다.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.1
• /
• pp.189-197
• /
• 2001

This paper presents hysteresis models of damping forces of a magneto-rheological (MR) damper which is applicable to a middle-sized passenger vehicle. After manufacturing a cylindrical type of the MR damper, its field-dependant damping force and hysteresis behavior are experimentally evaluated. Three different models ; Bingham model, Bouc-Wen model and Polynomial model are provided to predict the hysteretic damping force. The damping force characteristics predicted from three different models are compared with the measured results under various excitation conditions.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.10
• /
• pp.1034-1042
• /
• 2009

In this paper, the magic formula model was applied for a friction damper in a drum-type washing machine. To describe characteristics of the hysteretic damping force, Physical tests were first carried out to get experimental results using an MTS machine. Then, parameters for the magic formula model were determined from the experimental curves. The ADAMS and MATLAB programs were used for the multibody modeling of the damper and process for parameter identification. The model of drum-type washing machine was applied for a dynamic model of friction damper, in which the accuracy of the proposed damper model was verified.