• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.980-985
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• 2008

This paper presents vehicle road test of a semi-active suspension system equipped with continuously controllable magnetorheological (MR) dampers. As a first step, front and rear MR dampers are designed and manufactured based on the optimized damping force levels and mechanical dimensions required for a commercial middle-sized passenger vehicle. After experimentally evaluating dynamic characteristics of the MR dampers, the test vehicle is prepared for road test by integrating current suppliers, real-time data acquisition system and numerous sensors such as accelerometer and gyroscope. Subsequently, the manufactured four MR dampers (two for front parts and two for rear parts) are incorporated with the test vehicle and a skyhook control algorithm is formulated and realized in the data acquisition system. In order to emphasize practical aspect of the proposed MR suspension system, road tests are undertaken on proving grounds: bump and paved roads. The control responses are evaluated in both time and frequency domains by activating the MR dampers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.246-250
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• 2000

A distinctive feature in vibration control of a large civil infrastructure is the existence of large disturbances, such as wind, earthquake, and sea wave forces. Those disturbances govern the behavior of the structure, however, they cannot be precisely measured, especially for the case of wind-induced vibration control. The sliding mode fuzzy control (SMFC), which is of interest in this study, may use not only the structural response measurement but also the wind force measurement. Hence, an adaptive disturbance estimation filter is introduced to generate a wind force vector at each time instance based on the measured structural response and the stochastic information of the wind force. The structure of the filter is constructed based on an auto-regressive with auxiliary input model. A numerical simulation is carried out on a benchmark problem of a wind-excited building. The results indicate that the overall performance of the proposed SMFC is as good as the other methods and that most of the performance indices improve as the adaptive disturbance estimation filter is introduced.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.3
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• pp.235-242
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• 2009

This paper presents vehicle road test of a semi-active suspension system equipped with continuously controllable magnetorheological(MR) dampers. As a first step, front and rear MR dampers are designed and manufactured based on the optimized damping force levels and mechanical dimensions required for a commercial middle-sized passenger vehicle. After experimentally evaluating dynamic characteristics of the MR dampers, the test vehicle is prepared for road test by integrating current suppliers, real-time data acquisition system and numerous sensors such as accelerometer and gyroscope. Subsequently, the manufactured four MR dampers(two for front parts and two for rear parts) are incorporated with the test vehicle and a skyhook control algorithm is formulated and realized in the data acquisition system. In order to emphasize practical aspect of the proposed MR suspension system, road tests are undertaken on proving grounds: bump and paved roads. The control responses are evaluated in both time and frequency domains by activating the MR dampers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.368-373
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• 2003

This paper presents a study of low frequencies volume velocity vibration control of a smart panel in order to reduce sound transmission. A distributed piezoelectric quadratically shaped polyvinylidene fluoride (PVDF) polymer film is used as a uniform force actuator and an array of 4$\times$4 accelerometer is used as a volume velocity sensor for the implementation of a single-input single-output con rot system. The theoretical and experimental study of sensor-actuator frequency response function sho vs that this sensor-actuator arrangement provides a required strictly positive real frequency response function below about 900Hz. Direct velocity feedback could therefore be implemented with a limited gain which gives reductions of about 15㏈ in vibration level and about 8 ㏈ in acoustic power level at the (1, 1) mode of the smart Panel. It has been also shown that the shaping error of PVDF actuator could limit he stability and performance of the control system.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.10
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• pp.1036-1043
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• 2014

In this paper, a new haptic device is proposed for the teleoperation, which can recognize the invisible environment of a mobile robot. With this new device, it is possible for the user to identify the location of an obstacle and to avoid it. The haptic device has been attached on the top of a joystick so that the user can remotely control the mobile robot to avoid the obstacles which are recognized by the ultrasonic sensors. Also, the invisible environment is recognized more accurately overlapping the data from the ultrasonic sensors. There are five vibration motors in the haptic device to indicate the direction of the obstacle. So the direction of the obstacle can be recognized by the vibration at the finger on each vibration motor. For various situations and surrounding environments, experiments are performed using fuzzy controller and overlapping ultrasonic sensors. The results demonstrate the effectiveness of the proposed haptic joystick.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.392-395
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• 2011

In this paper, a vibration energy harvesting circuit using the piezoelectric element has been designed. MPPT (maximum power point tracking control) control function has been implemented to deliver the maximum power to the load by using the electric power-voltage characteristic of the piezoelectric element. The designed MPPT circuit traces the maximum power point by sampling periodically the open circuit voltage of the full wave rectifier circuit and delivers the maximum available power to the load. The vibration energy harvesting circuit is designed with $0.18{\mu}m$ CMOS process. The maximum power efficiency is 91%, and the chip area except pads is $1,100{\mu}m{\times}730{\mu}m$.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.317-319
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• 1996

In this paper, an active vibration control system using a voice coil type linear oscillating actuator(LOA) is studied to suppress structural vibration. Being compared with a hydraulic actuator, a LOA has simplified structure and requires a few elements in the driving system, so it has lots of merits with respect to economics and maintenance. The general mathematical dynamic model to obtain the algorithm for the realization of vibration active control system is treated. Actually, the performance test of the control system using LOA is carried out on a steel test structure under sinusoidal and white noise excitation. From this test it is conformed that acceleration level of test structure is reduced near the resonance region. In the future research on the application to large structures will be studied.

• Computers and Concrete
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• v.32 no.4
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• pp.411-423
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• 2023

The rapid development of road transport has increased the number of bridges that require widening. A critical issue in the construction of bridge widening is the influence of vibrations of the old bridge on the casting of wet joint concrete between the old and new bridges owing to the running traffic. Typically, the bridge is closed to traffic during the pouring of wet joint concrete, which negatively affects the existing transportation network. In this study, a newly developed microscopic traffic load modeling approach and the vehicle-bridge interaction theory are incorporated to develop a refined numerical framework for the analysis of random traffic-bridge coupled dynamics. This framework was used to investigate traffic-induced vibrations at the wet joint of a widened bridge. Based on an experimental study on the vibration resistance of wet joint concrete, traffic control strategies were proposed to ensure the construction performance of cast-in-site wet joint concrete under random traffic without interruption. The results show that the vibration displacement and frequency of the old bridge, estimated by the proposed framework, were comparable with those obtained from field measurements. Based on the target peak particle velocity and vibration amplitude of the wet joint concrete, it was found that traffic control measures, such as limiting vehicle gross weight and limiting traffic volume by closing an additional traffic lane, could ensure the construction performance of the wet joint concrete.

• Smart Structures and Systems
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• v.33 no.6
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• pp.415-430
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• 2024

To control vertical and lateral compound vibration simultaneously using an integrated smart controller, passive tuned mass damper (TMD) and tuned liquid damper (TLD) are updated and combined to an adaptive-passive TMD-TLD (AP-TMD-TLD) system. As for the vertical AP-TMD part on top of the vertical spring, it can retune itself through varying the level of liquid in the tank to adjust its mass, while the lateral AP-TLD part at the bottom of the vertical spring can retune itself by changing the level of liquid. Further, for multimodal response control, the multiple AP-TMD-TLD (MAP-TMD-TLD) system is proposed as well. Each AP-TMD-TLD in the system can identify the structural vertical and lateral modal frequencies through the wavelet-transform (WT) based algorithm and retune its vertical and lateral natural frequencies both through adjusting the level of liquid in the AP-TMD and AP-TLD parts respectively. A cantilever cable-stayed landscape bridge which is sensitive to both human-induced and wind-induced vibrations is presented as a case study. For comparison, initial parameters of MAP-TMD-TLD are mistuned. Results show that the presented system can retune its vertical and lateral frequencies precisely, while the retuned system has a better bi-directional compound control effect than the mistuned system before the retuning operation and can improve the serviceability significantly.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.221-226
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• 1996

Structural vibrations of adjacent buildings, manufacturing factories and engines on the stationary diesel power plant were increased by the variation of phase angle between two engines sometimes. In this paper, top bracings and synchrophaser have been introduced in order to reduce these vibrations. As a result, all of structural vibrations were greatly improved by the phase adjustment of 6th order X-mode vibration with these.