• Proceedings of the KSR Conference
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• 2011.10a
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• pp.75-80
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• 2011

In the area of wheel on rail vehicle, hunting stability which is generated by lateral motion is one of important characteristics for running safety. It might cause not only oscillation of vehicle but also derailment in an unstable area of the high speed. A Maglev vehicle is usually controlled the voltage to maintain the air gap between electromagnet and track. However, in Maglev system, an occurrence possibility of hunting motion could be high, because Maglev vehicle is not controlled directly lateral force between electromagnet and track in the curved guideway. In this paper, running safety is evaluated when Maglev vehicle run on guideway at high speed according to installment of damper between maglev vehicles and bogies, and to analyze the effect of it. Also, the parametric study is carried out for selecting effective lateral damper properties through the simulation. To accurately predict the running safety, 3d multibody dynamics models which are included air spring, guideway conditions and irregularities profile are used. With the results acquired, suggestions were made whether to adopt the damper and how to optimize the damping characteristics.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.1
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• pp.27-38
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• 2016

The purpose of this study is to investigate the influence of moving mass on the vibration characteristics and the dynamic response of the simply supported beam. The three types of the moving mass(moving load, unsprung mass, and sprung mass) are applied to the vehicle-bridge interaction analysis. The numerical analyses are then conducted to evaluate the effect of the mass, spring and damper properties of the moving mass on natural frequencies and dynamic responses of the simply supported beam. Particularly, in the case of the sprung mass, variations of the natural frequency of simply supported beam are explored depending on the position of the moving mass and the frequency ratio of the moving mass and the beam. Finally the parametric studies on the resonance phenomena are performed with changing mass, spring and damper parameters through the dynamic interaction analyses.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.54-63
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• 2022

This paper is a study on the friction damper, which is one of the seismic reinforcement devices for structures. This study developed a damper by replacing the internal friction material with ultra high molecular weight polyethylene (UHMWPE), a type of composite material. In addition, this study applied a multi-friction method in which the internal structure where frictional force is generated is laminated in several layers. To verify the performance of the developed multi-friction damper, this study performed a characteristic analysis test for the basic physical properties, wear characteristics, and disc springs of the material. As a result of the wear test, the mass reduction rate of UHMWPE was 0.003%, which showed the best performance among the friction materials based on composite materials. Regarding the disc spring, this study secured the design basic data from the finite element analysis and experimental test results. Moreover, to confirm the quality stability of the developed multi-friction damper, this study performed an seismic load test on the damping device and the friction force change according to the torque value. The quality performance test result showed a linear frictional force change according to the torque value adjustment. As a result of the seismic load test, the allowable error of the friction damper was less than 15%, which is the standard required by the design standards, so it satisfies the requirements for seismic reinforcement devices.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.6 s.99
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• pp.764-771
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• 2005

This study investigates the 3-axis transmissibility of the vehicle compact disk player's mainbase which is supported by dampers and springs. These dampers and springs as the important element ' determining the vibration performance of vehicle compact disk Player are used to minimize the vibration which is induced by driving the vehicle. In order to determine the analysis frequency band, we investigated the excitation frequency of road from the vehicle test. As the characteristics of damper and spring were changed, we carried out the vibration test and investigated the change of transmissibility, Also, we carried out the sensitivity analysis for transmissibility and we found out that the properties of damper were the dominant element in the vibration performance of vehicle compact disk player.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.139-142
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• 1996

This paper presents a method of controlling contact force for deburring tasks. The cope with the nonlinearities and time-varying properties of the robot and the environment, a neural network control theory is applied to design the contact force control system. We show that the contact force between the hand and the contacting surface can be controlled by adjusting the command velocity of a robot hand, which is accomplished by the modeling of a robot and the environment as Mass-Spring-Damper system. Simulation results are shown.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.3 s.55
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• pp.33-42
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• 2007

In this study, for research on an improvement of the seismic safety of an EDG system, a small scale EDG system was manufactured. For the isolation system, the Coil Spring-Viscous Damper systems were selected. For the shaking table test, 3 kinds of seismic motions were selected which had different frequency contents. In this study, the isolation effects were different and they depended on the input seismic motion. In the case of an NRC earthquake which had low fiequency contents, the isolation effects of the horizontal direction were 20%. But for the seismic motions which had high fiequency contents, the isolation effects were $50{\sim}70%$. In the case of the vertical direction, poor isolation effects were observed. It was because the design properties and the real properties of the isolation system were a little different.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.209-218
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• 2004

The purpose of this paper is to suggest a practical and simple method for the identification of the joint mechanical properties and to apply it to human knee joints. The passive moment at a joint was modeled by three mechanical parts, that is, a gravity term, a linear damper term and a nonlinear spring term. Passive pendulum tests were performed in 5 fat and 5 thin men. The data of pendulum test were used to identify the mechanical properties of joints through sequential quadratic programming (SQP) with random initial values. The identification was successful where the normalized root-mean-squared (RMS) errors between the simulated and experimental joint angle trajectories were less than 10％. The parameter values of mechanical properties obtained in this study agreed with literature. The inertia, gravity and the damping constant were greater at fat men, which indicates more resistance to body movement and more energy consumption fer fat men. The suggested method is noninvasive and requires simple setup and short measurement time. It is expected to be useful in the evaluation of joint pathologies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.3
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• pp.472-477
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• 2003

A piezo-actuator is an important component for an E-beam lithography system. But it is very difficult to model its characteristics due to nonlinearities such as hysteresis and creep, to the input voltage. In this paper, one-axis micro stage with a piezo-actuator is modeled including the nonlinear properties. Hysteresis and creep are modeled as the first order differential equation and a time-dependent logarithmic function, respectively. The dynamic motion of the stage is also modeled as a mass-spring-damper system and the parameters are determined by utilizing the system identification technique. The simulation tool for a micro stage is constructed using the commercial software and its simulation results are compared with the experimental data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1900-1906
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• 2000

In this study, the vibration screening effectiveness of barriers which can isolate structures from ground-transmitted vibration generated by harmonic forces is performed. For high frequencies, the vibration screening effectiveness of barriers is analyzed from field tests, and compared with the results from numerical analyses using a commercial program, ANSYS. Using these numerical analysis procedures, the effectiveness for vibration with various low frequencies is predicted. The frequency analysis tests of surface waves are performed in order to estimate the dynamic material properties of soil for 100 Hz, 150 Hz, 200 Hz, and 250 Hz. Three-dimensional solid elements are used in order to consider the diffraction of waves in all directions. Spring-damper combination elements are used in order to avoid the reflection of waves on the boundary. The results of numerical analysis agree with those of field tests. From the results of this numerical analyses, the reduction of vibration for low frequencies induced by the traffic loads can be predicted.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.9
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• pp.130-138
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• 1997

In this study, to improve the ride and handling characteristics of the vehicle whose hard points have been already fixed, a tuning method of load spring, damper and stabilizer bar is described. For the suspension system of vehicle, optimized design is necessary to satisfy the incompatible two dynamic characteristics which are the ride isolation property between unsprung mass and sprung mass to reduce the excitation from the road and the accurate correring response property to specific steering inputs. To accomplish above aims, we may approach by experimental method, but it requires to sacrifice much time and cost. This paper, therefore, provides a process of suspension development to improve the ride and handling properties by using computer simulation with saving time and cost, and as results, comparaes the dynamic characteristics of the tuned vehicle with the base vehicle not tuned.