• 정보저장시스템학회논문집
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• 제7권2호
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• pp.70-74
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• 2011

The mobile camera module is a device to be inserted in the digital device for camera feature. The mobile camera module is being shaken by vibrations such as handshake during the exposure time. The clarity is compromised by these vibrations, thus the vibration is considered as an external disturbance. Moreover the use of mobile camera module has been being expanded for automotive vibration should be considered. These external disturbances can cause image blurring, thus optical image stabilization should be applied for image compensation. The compensator is fulfilled mechanically by movable lens group or image sensor that adjusts the optical path to the camera movement. Open loop control is useful for well-defined systems like compliant mechanism. Notch filter and lead compensator are designed and applied to improve the stability and bandwidth. The final level of image compensating is confirmed by image processing with MATLAB and CODE V to verify the better performance.

• International Journal of Railway
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• 제6권3호
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• pp.95-106
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• 2013

Earthborne vibrations are induced by construction operation such as pile driving, roadbed compaction, and blasting and also by transit activities such as truck and trains. The earthborne vibration creates the stress waves traveling outward from the source and can structurally damage nearby buildings and structures in the forms of direct damage to structure and damage due to dynamic settlement. The wave propagation characteristics depends on impact or vibration energy, distance from the source, and soil characteristics. The aim of this paper is to provide a comprehensive review on the mechanistic of earthborne vibration and the current practice of vibration control and mitigation measures. The paper describes the state of knowledge in the areas of: (1) mechanics of earthborne vibration, (2) damage mechanism by earthborne vibration, (3) calculation, prediction of ground vibration, (4) the criteria of vibration limits, (5) vibration mitigation measures and their performance, and (6) the current practice of vibration control and mitigation measures.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.432-439
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• 2006

Long span, high-rise bridges are rapidly increasing nowadays. Because of high flexibility, such bridges are easily excited by winds, vehicles, and pedestrians. The vibration of bridge induces a vibration of lamp post and pillar. Wind loads can also excite lamp posts and traffic signal structures directly. Because of low damping, such vibrations of lamp post are frequently amplified and come to collapse or lamp failure. In addition, such vibration makes the maintenance cycle shorter and increases social cost. We conducted vibration tests and identified the dynamic characteristics of two types lamp posts, and proposed tuned mass dampers to control the vibrations. Established models of the lamp posts present the dynamic characteristics of the structures very well and they are used to design TMDs. In this study, we suggested a new-type TMD model that is small, simple, economic and effective to suppress the vibration of lamp posts. The efficiency of TMD was examined by numerically and is to be examined experimentally.

• Smart Structures and Systems
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• 제24권3호
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• pp.391-401
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• 2019

Control of vibrations against extraordinary excitations such as wind and earthquake is very important to the protection of life and financial concerns. One of the methods of structural control is to use Tuned Liquid Damper (TLD), however due to the nature of TLD only one sloshing frequency can be created when the water is sloshing. Among various ideas proposed to compensate this problem, by changing the angle of some rotatable baffles embedded inside a TLD, a frequency range is created such that these baffles are tuned manually at different frequencies. In this study, the effect of cross sectional shape of container with rotating baffles on seismic behavior of TLD is experimentally studied. For this purpose, rectangular and cylindrical containers are designed and used to suppress the vibrations of a Single Degree-Of-Freedom (SDOF) structure under harmonic and earthquake excitations considering three baffle angles. The results show that the rectangular-shaped damper reduces the structural response in all load cases more than the damper with a cylindrical shape, such that maximum differences of two dampers to reduce the structural displacement and structural acceleration are 5.5% and 3% respectively, when compared to the cases where no baffles are employed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.153-158
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• 2004

In this paper, we proposed a two-stage control of the container crane. The first stage control is time-optimal control for the purpose of fast trolley traveling. With suitable trolley velocity patterns, the sway which is generated during trolley moving is minimized. At the second stage control feedback control law is investigated for the quick suppression of residual vibration after the trolley motion. For more practical system, the container crane system is modeled as a partial differential equation (PDE) system with flexible cable. The dynamics of the cable is derived as a moving system with tension caused by payload using Hamilton's principle for the systems. A control law based upon the Lyapunov's method is derived. It is revealed that a time-varying control force and a suitable passive damping at the actuator can successfully suppress the transverse vibrations.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1993년도 추계학술대회논문집; 반도아카데미, 26 Nov. 1993
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• pp.157-161
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• 1993

Optical devices and electronic equipments used in the laboratory of the synchrotron light source building of the accelerator have stringent vibration limits. In order to control the vibration of the building structure and HVAC systems which are main vibration sources are evaluated using experimental modal analysis. Double anti-vibration system is used for the HVAC system and results show that the double anti-vibration system reduces the vibrations of the building to acceptable levels.

• 소음진동
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• 제8권6호
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• pp.1121-1129
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• 1998

This research is concerned with the multiple PPF and the modified LQG controller design for active vibration control of intelligent structures. The intelligent structure is defined as the structure equipped with smart actuators and sensors. Various control techniques aimed for the piezoceramic sensors and actuators have been proposed for the active vibration control of smart structures and some of them prove their effectiveness experimentally. In this paper, the multiple PPF controller and the modified LQG controller are developed and applied to the smart grid structure. The multiple PPF control and the modified LQG control can be classified as the classical and the modern control techniques. respectively. The experimental results show that both control techniques are effective in suppressing vibrations. Two control techniques are compared with respect to the design process. the ease of implementation and the effectiveness

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.54.2-54
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• 2001

In this paper two control strategies, command shaping control and optimal control, which aim to the reduction of the residual vibrations of the payload in a container crane system are investigated. Both control methods are open loop control. Due to unmodeled dynamics of the plant and disturbances like initial sway and wind, some residual sway always exists at the end of trolley movement. Command inputs are designed to achieve the control objectives including minimal residual vibration and robustness in the presence of unmodeled dynamics. Simulation results of various command inputs are compared in terms of arrival time, residual sway angle, robustness, and maximum sway distance during the traveling. Command shaping method provides a more competent tool than optimal control.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.151-154
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• 1997

An open loop vibrational control of underactuated mechanical systems with amplitude and frequency modulations is investigated. The underactuated systems considered in the paper are assumed to have free joints with no brake. The active joints are positioned first by a linearizing control, and then periodic oscillatory inputs are applied to them to move the remaining free joints to their desired states. A systematic way of obtaining averaged systems for the underactuated systems with oscillatory vibrations is developed. A complete solution to the open loop control strategy in terms of determining amplitudes and frequencies for general system is still under investigation. However, a specific control design for 2R manipulator which is obtained the averaging system is demonstrated.

• Smart Structures and Systems
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• 제13권3호
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• pp.435-451
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• 2014

In this paper, we investigate the vibration control of multimodal structures and present an efficient control law that requires less energy supply than active strategies. This strategy is called modal global semi-active control and is designed to work as effectively as the active control and consume less power which represents its major limitation. The proposed law is based on an energetic management of the optimal law such that the controller follows this latter only if there is sufficient energy which will be extracted directly from the system vibrations itself. The control algorithm is presented and validated for a cantilever beam structure subjected to external perturbations. Comparisons between the proposed law performances and those obtained by independent modal space control (IMSC) and semi-active control schemes are offered.