• Title/Summary/Keyword: 잔류 진동

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A Study on the Balancing of V/W-type Reciprocating Air Compressor (V/W형 왕복동 공기압측기의 평형에 관한 연구)

  • 김형진;김성춘;김정만;김의간
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.1
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    • pp.24-31
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    • 2004
  • Recently, as the marine compressor power is increased, vibration problems on the marine vessel with V/W type reciprocating compressor have been occurred. A research on the balancing of marine V/W type reciprocating compressor has hardly been reported though a number of researches on the balancing of rotating machinery have been conducted. As a V/W type compressor has high capacity with long stroke, compact size and high center of gravity, It is easy to have a vibration problem by a little bit unbalanced force and moment. In this study, calculation methods for balance weight of the V/W type reciprocating compressors, which have different piston weight and asymmetry structure, are formulated. And their reliability were verified by comparing calculated balance weight with the experimental results of the real marine V/W type reciprocating compressors.

Active Control of Reaction Forces for Flexible Structures (유연 구조물의 능동 반력 제어기 설계)

  • 김주형
    • Journal of KSNVE
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    • v.11 no.1
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    • pp.68-75
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    • 2001
  • A method for actively controlling dynamic reaction forces in flexible structures subject to persistent excitations is presented. Since reaction forces are not directly measured in flexible structures, reaction forces are estimated by using the Kalman filter. The estimated reaction force is used as an error signal in the adaptive feedforward disturbance cancellation controller. In order to compensate the static effect of the truncated modes in the reaction forces, the residual flexibility matrix is used with the Kalman filter. The paper presents the formulation of the reaction forces in conjunction with the Kalman filter estimator and the adaptive feedforward controller. The results show that the dynamic reaction forces at its supports in a flexible beam test rir are well suppressed.

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Modeling and Motion Control of the Piezoelectric Actuator for the Inchworm: Part 1. Hysteresis Modeling of the Piezoelectric Actuator (이송자벌레를 위한 압전소자의 모델링 및 운동제어: 1. PZT소자의 히스테리시스 모델링)

  • Kim, In-Soo;Kim, Gibum;Kim, Young-Shik
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.7 s.100
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    • pp.871-877
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    • 2005
  • This paper proposes a new modeling scheme to describe the hysteresis between input voltage and displacement of piezoelectric actuators in the inchworm. From the experimental analysis of Piezoelectric actuator behaviors. the hysteresis characteristics including residual displacement can be modeled by second order functions of a maximum Input voltage and preload. Various experiments are performed to demonstrate the effectiveness and validation of the proposed modeling scheme.

ISO/TC/108/SCl 1940-1(Mechanical vibration - Balance quality requirements of rigid rotors- Determination of permissible residual unbalance) (강성회전체의 평형특성 요구조건 - 허용 잔류불평형량의 결정 (ISO 1940-1))

  • 최상규;전오성
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.05a
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    • pp.889-898
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    • 2002
  • This part of ISO 1940 gives recommendations for determining unbalance and for specifying related quality requirements of rigid rotors; it specifies a) a representation of unbalance in one or two planes; b) methods for determining permissible residual unbalance; c) methods for allocating it to the correction planes; d) methods for identifying he residual unbalance state of a rotor by measurement; e) a summary of errors associated with the residual unbalance identification. This part of ISO 1940 is also intended to facilitate the relations between manufacturer and user of machines. Detailed consideration of errors associated with the determination of residual unbalance is covered in the 2nd part of ISO 1940 (ISO 1940-2 will deal with these errors).

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Mineralogical Characteristics and Formation Processes of Zonal Textures in Hydrothermal Epidote from the Bobae Sericite Deposit (보배 견문모 광상에서 산출하는 녹염석의 누대구조의 특징과 발달과정)

  • 추창오
    • Economic and Environmental Geology
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    • v.34 no.5
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    • pp.437-446
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    • 2001
  • Zoned epidotes formed by the propylitic alteration of the Bobae sericite deposit in western Pusan show complex compositional zoning patterns, such as multiple growth zoning, oscillatory zoning, patchy zoning and irregular zoning. The complex zoned epidote, in general, shows AI-rich cores and Fe-rich rims. Pistacite component (Ps) in the epidote ranges from 18.5 to 74.3 mot.%. Remnant textures in multiple growth zoning indicate that the earlier zone was partially resorbed prior to growth of later one. Multiple growth zoning and oscillatory zoning suggest that hydrothermal system underwent rapid changes and fluctuations in fluid chemistry, redox condition, or temperature.

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Active Optimal Control Techniques for Suppressing Dynamic Load in Vibration (진동에서 생기는 동적 하중을 줄이기 위한 능동 최적 제어)

  • 김주형;김상섭
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.10
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    • pp.749-757
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    • 2002
  • Excessive vibration in flexible structures is a problem encountered in many different fields, causing fatigue of structural components. Passive techniques, though sometimes limited in their capabilities, have been used in the past to attenuate vibrations. Recently active techniques have been developed to enhance vibration control performance beyond that provided by their passive counterparts. Most often, the focus of active control methods has been to suppress structure displacements. In cases where vibration results in structure failures, displacement suppression may not be the best choice of control approaches (it can, in fact, increase dynamic loads which would be even more harmful to supports) . This paper presents two optimal control methods for attenuating steady state vibrations in flexible structures. One method minimizes shaft displacements while another minimizes dynamic reaction forces. The two methods are applied to a model of a typical flexible structure system and their results are compared. It is found that displacement minimization can increase loads, while load minimization decreases loads.

Development of Finite Element Model for Dynamic Characteristics of MEMS Piezo Actuator in Consideration of Semiconductor Process (반도체 공정을 고려한 유한요소해석에 의한 MEMS 압전 작동기의 동특성 해석)

  • Kim, Dong Woohn;Song, Jonghyeong;An, Seungdo;Woo, Kisuk
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.04a
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    • pp.454-459
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    • 2013
  • For the purpose of rapid development and superior design quality assurance, sophisticated finite element model for SOM(Spatial Optical Modulator) piezo actuator of MOEMS device has been developed and evaluated for the accuracy of dynamics and residual stress analysis. Parametric finite element model is constructed using ANSYS APDL language to increase the design and analysis performance. Geometric dimensions, mechanical material properties for each thin film layer are input parameters of FE model and residual stresses in all thin film layers are simulated by thermal expansion method with psedu process temperature. $6^{th}$ mask design samples are manufactured and $1^{st}$ natural frequency and 10V PZT driving displacement are measured with LDV. The results of experiment are compared with those of the simulation and validate the good agreement in $1^{st}$ natural frequency within 5% error. But large error over 30% occurred in 10V PZT driving displacement because of insufficient PZT constant $d_{31}$ measurement technology.

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Vibration Control of Buildings Connected by a Sky-Bridge (SKY-BRIDGE로 연결된 건물의 진동제어)

  • 류진국;김진구
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.17 no.2
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    • pp.203-213
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    • 2004
  • This study investigates the seismic responses of two structures connected by a sky-bridge equipped with viscoelastic dampers (VED) at the bridge-building connections. The applicability of the method is verified first by observing RMS (root-mean-squared) responses of two-degrees-of-freedom systems subjected to white noise ground excitation. Then model structures with various number of stories are analyzed using earthquake ground motions to observe the effect of the varying size of VED on the reduction of dynamic responses. According to the analysis results, there exists a proper size of VED which minimizes the structural responses. It is also observed that the effectiveness of VED increases as the difference of natural frequencies between the two connected structures increases.

Straight-line Path Error Reduction for the End of a Flexible Beam Deploying from a Rotating Rigid Hub (회전하는 강체허브에서 전개하는 보 끝단의 직선궤적오차 저감)

  • Kim, Byeongjin;Kim, Hyungrae;Chung, Jintai
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.11
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    • pp.898-906
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    • 2014
  • This paper presents a reduction method for a straight-line path error of a flexible beam deploying from a rotating rigid hub. Previous studies discussed about only vibration phenomena of flexible beams deploying from rotating hubs; however, this study investigates a vibration reduction of a rotating beam with variable length. The equation of motion and associated boundary conditions are derived for a flexible beam deploying from a rotating rigid hub, and then they are transformed to a variational equation. By applying the Galerkin method, the discretized equations are obtained from the variational equation. Based on the discretized equations, the dynamic responses of a rotating/deploying beam are analyzed when the beam end has a straight line motion. A reduction method for the trajectory error is proposed, using the average length of a rotating/deploying beam. It is shown that the proposed method is able to reduce the residual vibration of a rotating/deploying beam.

Dynamic Load Suppression in Active Vibration Control of Rotating Machinery (회전 물체의 동적 하중에 대한 능동 진동 제어)

  • 김주형;김상섭
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11b
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    • pp.1126-1131
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    • 2001
  • Excessive vibration in rotating machinery is a problem encountered in many different fields, causing such difficulties as fatigue of machinery components and failure of supporting bearings. Passive techniques, though sometimes limited in their capabilities, have been used in the past to attenuated vibrations. Recently active techniques have been developed to provide vibration control perform beyond that provided by their passive counters. Most often, the focus of active control methods has been to suppress rotating machinery displacements. In cases where vibration results in bearing failures, displacement suppression may not be the best choice of control approaches (it can, in fact, increase dynamic bearing loads which would be even more harmful to bearings). This paper presents two optimal control methods for attenuating steady state vibrations in rotating machinery. One method minimizes shaft displacements while the other minimizes dynamic bearing reaction forces. The two methods are applied to a model of a typical rotating machinery system and their results are compared. It is found that displacement minimization can increase bearing loads, while bearing load minimization, on the other hand, decreases bearing loads.

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