• Title/Summary/Keyword: vibrational control

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A Study on The Identification of Characteristics For The 2 Dimensional Continuous Vibration System By Mass Sensitivity Analysis (질량감도 해석에 의한 2차원 연속계의 진동특성에 관한 연구)

  • Lee, Jung-Yoon;Park, Ho;Oh, Jae-Eung
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.2
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    • pp.339-348
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    • 1990
  • Techniques which are able to predict and control dynamic characteristics, not affecting the vibrational characteristics on the modification of structural design, are being studied. As one of these techniques, experimental modal analysis is widely applied by many researchers. In this study, modal analysis is performed using transfer matrix method by a macro computer. The developed program would estimate the structural modal parameters precisely, and the validity of this program is certified by comparing with the experimental results of .GAMMA A. structure. Estimated modal parameters(natural frequency, vibrational mode, equivalent mass, etc.) are in accord with the experimental results. Also, the optimal location of the additive mass is determined by the evaluation of the vibrational mode and the equivalent mass. The relation between the additive mass and the equivalent mass is specified, and we come to know that the ratio of equivalent mass to additive mass alter linearly within the range of 20%.

A Study on the Vibrational Environment Test of KSLV-1 Demonstration Satellite (한국형 위성 발사체 성능 검증위성의 진동환경에 관한 연구)

  • Seo, Hyun-Suk;Kim, Hong-Bae;Woo, Sung-Hyun;Chae, Jang-Soo;Oh, Tae-Sik
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.966-970
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    • 2005
  • On the basis of the development of KSLV-1, KoDSat was designed and manufactured to demonstrate the performance of KSLV-1. KoDSat is exposed to a severe vibrational environment at launch. The structural reliability of KoDSat has to be verified using vibrational test. The structural compatibility and verification of components between analysis and test can be proved using environmental vibration test. In this paper, we review the structural characteristic of thruster control unit for a space launch vehicle and design TCU housing using mathematical model. In order to verify the structural compatibility and reliability, half-sine shock, random and sing sweep vibration test was performed. Especially, sing sweep vibration test result is compared with analysis result and mathematical model is verified.

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Wind vibration control of stay cables using an evolutionary algorithm

  • Chen, Tim;Huang, Yu-Ching;Xu, Zhao-Wang;Chen, J.C.Y.
    • Wind and Structures
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    • v.32 no.1
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    • pp.71-80
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    • 2021
  • In steel cable bridges, the use of magnetorheological (MR) dampers between butt cables is constantly increasing to dampen vibrations caused by rain and wind. The biggest problem in the actual applications of those devices is to launch a kind of appropriate algorithm that can effectively and efficiently suppress the perturbation of the tie through basic calculations and optimal solutions. This article discusses the optimal evolutionary design based on a linear and quadratic regulator (hereafter LQR) to lessen the perturbation of the bridges with cables. The control numerical algorithms are expected to effectively and efficiently decrease the possible risks of the structural response in amplification owing to the feedback force in the direction of the MR attenuator. In addition, these numerical algorithms approximate those optimal linear quadratic regulator control forces through the corresponding damping and stiffness, which significantly lessens the work of calculating the significant and optimal control forces. Therefore, it has been shown that it plays an important and significant role in the practical application design of semiactive MR control power systems. In the present proposed novel evolutionary parallel distributed compensator scheme, the vibrational control problem with a simulated demonstration is used to evaluate the numerical algorithmic performance and effectiveness. The results show that these semiactive MR control numerical algorithms which are present proposed in the present paper has better performance than the optimal and the passive control, which is almost reaching the levels of linear quadratic regulator controls with minimal feedback requirements.

VIBRATIONAL SPECTROSCOPY IN INDUSTRIAL CHEMICAL QUALITY CONTROL

  • Siesler, H.W.
    • Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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    • 2001.06a
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    • pp.1081-1081
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    • 2001
  • The constant need for quality improvement and production rationalization in the chemical and related industries has led to the increasing replacement of conservative control procedures by more specific and environmentally compatible analytical techniques. In this respect, vibrational spectroscopy has developed over the last yews - in combination with new instrumental accessories and statistical evaluation procedures - to one of the most important analytical tools for industrial chemical quality control and process monitoring in a wide field of applications. In the present communication this potential is demonstrated in order to further support the implementation of mid-infrared (MIR), near-infrared (NIR) and Raman spectroscopy Primarily as industrial on-line tools. To this end the data of selected feasibility studies will be discussed in terms of the individual strengths of the different techniques for the respective application.

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Active Vibration Control of a Composite Beam Using Piezoelectric Films (압전필름을 이용한 복합재료 외팔보의 능동진동제어)

  • Kim, S.H.;Choi, S.B.;Cheong, C.C.
    • Journal of the Korean Society for Precision Engineering
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    • v.11 no.1
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    • pp.54-62
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    • 1994
  • This paper presents active control methodologies to suppress structural deflections of a composite beam using a distributed piezoelectric-film actuator and sensor. Three types of different controllers are employed to achieve vibration suppression. The controllers are established depending upon the information on the velocity components of the structrue and on the deflection magnitudes as well. They are constant-amplitude controller(CAC), constant-gain mcontroller(CGC), and constant-amplitude-gain controller(CAGC). For the minimization of the residual vibration (chattering in a settled phase), which is the practical shortcoming of the conventional CAC dur to time delay phenomenon of the hardware system, a new control algoritym CAGCis designed by selecting switching constants in an optimal manner with respect to the initial tip deflection and the applied voltage. The experimental investigations of the transient and forced vibration control for the first vibrational mode are undertaken in order to compare the suppression efficiency of each control algorithm. Moreover, simultaneous controllability of various vibrational modes through the proposed scheme is also experimentally verified by pressenting both the transfer function and the phase.

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Identification and suppression of vibrational energy in stiffened plates with cutouts based on visualization techniques

  • Li, Kai;Li, Sheng;Zhao, De-You
    • Structural Engineering and Mechanics
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    • v.43 no.3
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    • pp.395-410
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    • 2012
  • The visualizing energy flow and control in vibrating stiffened plates with a cutout are studied using finite element method. The vibration intensity, vibration energy and strain energy distribution of stiffened plates with cutout at different excitation frequencies are calculated respectively and visualized for the various cases. The cases of different size and boundaries conditions of cutouts are also investigated. It is found that the cutout or opening completely changes the paths and distributions of the energy flow in stiffened plate. The magnitude of energy flow is significantly larger at the edges near the cutout boundary. The position of maximum strain energy distribution is not corresponding to the position of maximum vibrational energy. Furthermore, the energy-based control using constrained damping layer (CDL) for vibration suppression is also analyzed. According to the energy distribution maps, the CDL patches are applied to the locations that have higher energy distribution at the targeted mode of vibration. The energy-based CDL treatments have produced significant attenuation of the vibration energy and strain energy. The present energy visualization technique and energy-based CDL treatments can be extended to the vibration control of vehicles structures.

Real-time Feedback Vibration Control of Structures Using Wireless Acceleration Sensor System - System Design and Basic Performance Evaluation - (무선 가속도센서 시스템을 이용한 건축물의 실시간 피드백 진동제어 - 시스템 구축 및 기초성능 평가 -)

  • Jeon, Joon Ryong;Park, Ki Tae;Lee, Chin Ok;Heo, Gwang Hee;Lee, Woo Sang
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.2
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    • pp.21-32
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    • 2013
  • This is a preliminary study for the real-time feedback vibration control of building structures. The study developed a wireless acceleration sensor system based on authentic technology capacities, to integrate with the Prototype AMD system and ultimately construct the feedback vibration control system. These systems were used to evaluate the basic performance levels of the control systems within model building structures. For this purpose, the study first developed a wireless acceleration sensor unit that integrates an MEMS sensor device and bluetooth communication module. Also, the study developed an operating program that enables control output based on real-time acceleration response measurement and control law. Furthermore, the Prototype AMD and motor driver system were constructed to be maneuvered by the AC servo-motor. Eventually, all these compositions were used to evaluate the real-time feedback vibration control system of a 2-story model building, and qualitatively measure the extent of vibrational reduction of the target structure within the laboratory validation tests. As a result of the tests, there was a definite vibrational reduction effect within the laboratory validation tests. As a result of the tests, there was a definite vibrational reduction effect within 1st and 2nd resonance frequency as well as the random frequency of the model building structure. Ultimately, this study confirmed the potential of its wireless acceleration sensor system and AMD system as an effective tool that can be applied to the active vibration control of other structures.

Vibrational Analysis of Slab Tracks Considering Wheel-Rail Interaction (차륜-레인 상호작용을 고려한 슬래브 궤도의 진동해석)

  • 이희현
    • Computational Structural Engineering
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    • v.7 no.2
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    • pp.77-87
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    • 1994
  • Vibrational analysis of slab tracks for HSR(High Speed Rail) is performed in order to find dynamic characteristics and to control noise and vibration for the tracks. Wheel-rail interactive force is included in the analysis by modelling the vehicle and track as an unsprung mass and elastically-supported-double-beam respectively, and both are assumed to be connected by the Hertzian spring. From this study, it has been found that vibration in the track and the force transmitted to the infrastructure could be reduced by controlling elasticity, mass and stiffness of the track supporting system appropriately.

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Surface Cleaning of Polyethylene Terephthalate Film with Non-equilibrium Atmospheric Discharge Plasma

  • Sung, Youl-Moon
    • Transactions on Electrical and Electronic Materials
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    • v.9 no.2
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    • pp.79-83
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    • 2008
  • The dampness by treating the surface with polyethylene terephthalate (PET) film was measured to grasp the plasma parameters and was observed the surface condition with an atomic force microscope (AFM) to find the causes of the dampness. Also, the vibrational and rotational temperatures in the plasma were calculated after identifying the radicals within the plasma by analyzing the emission spectral with an emission spectrum. The hydrophilic properties were enhanced, by treating the surface of the PET film with non-equilibrium atmospheric discharge plasma. When the rotational temperature was 0.22 to 0.31 eV within the plasma, surface modification control could be easily carried out to surface treatment of PET film on non-equilibrium atmospheric pressure plasma.

Comparison of Centralized and Decentralized Control for Vibration Suppression of a Beam (보의 진동억제를 위한 중앙화 및 비중앙화 제어의 비교 연구)

  • Lee, Young-Sup
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.494-497
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    • 2005
  • Direct velocity feedback (DVFB) control with a collocated distributed actuator and point sensor pair is known that it offers a good stability with high performance when the control strategy is applied at the suppression of structural vibration. Also decentralized control method introduced to offer to reduce implementaion effort and malfunction due to failure in sensors and actuators of control system has become an important position in DVFB. In this paper, the decentralized control is compared with centralized control in terms of vibrational velocity reduction in a clamped-clamped beam.

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