• Title/Summary/Keyword: Rotating Time

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A Study on Dynamic Characteristics of Rotating Transmission Using PID Control (PID 제어기를 이용한 회전전동장치의 동특성에 관한 연구)

  • Kim Jae-Kyung;Kim Jong-Tye;Kim Taek-Hyun
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.14 no.5
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    • pp.41-48
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    • 2005
  • The Rotating transmission is made up of belts, mass disks and gears. This transmission is controlled electro-mechanically by the motor and operation program. The control strategy of the system can be to change belts' stiffness and the masses of mass disk and gear. This system can be modeled as a rigid body, and also finds broad application in such diverse fields as machine tools, the cruise control system In automobiles, and control in the attitude and gimbals of spacecraft. This Transmission proves the necessity and effect of a closed loop control. The study of the Rotating Transmission excited by its base motion is able not only to predict the rotational performance, but to obtain the fundamental data for vibration isolation. In this research, we compared the response characteristics of the two controllers by means of the experiments on PD controller and PID controller added on integral action. Furthermore, we studied the response abilities such as steady state error, overshoot, and ect. and the response velocities such as rising time, settling time, and ect. in the rotating transmission.

A Study on Dynamic Characteristics of Rotating Transmission Using PD Control (PD 제어기를 이용한 회전전동장치의 동특성에 관한 연구)

  • Kim J.K.;Kim J.T.;Kim T.H.;Oh T.Y.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.715-720
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    • 2005
  • The rotating transmission is made up of belts, mass disks and gears. This precise piece of equipment is controlled electro-mechanically by the mote. and operation program. The control strategy and the transmission can be changed by belts' stiffness and change of the mass and gear. This transmission can be modeled as a rigid body, and also finds broad application in such diverse fields as machine tools, the cruise control system in automobiles, and control in the attitude and gimbals of spacecraft. The study of the rotating transmission excited by its base motion is not only able to predict the rotational performance, but obtain the fundamental data for vibration isolation. In this thesis, we studied the response abilities such as steady overshoot, undershoot and ect. and the response velocities such as rising time, settling time, and ect. in the rotating transmission through PD control experiment.

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REAL-TIME DETECTION OF MOVING OBJECTS IN A ROTATING AND ZOOMING CAMERA

  • Li, Ying-Bo;Cho, Won-Ho;Hong, Ki-Sang
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2009.01a
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    • pp.71-75
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    • 2009
  • In this paper, we present a real-time method to detect moving objects in a rotating and zooming camera. It is useful for camera surveillance of fixed but rotating camera, camera on moving car, and so on. We first compensate the global motion, and then exploit the displaced frame difference (DFD) to find the block-wise boundary. For robust detection, we propose a kind of image to combine the detections from consecutive frames. We use the block-wise detection to achieve the real-time speed, except the pixel-wise DFD. In addition, a fast block-matching algorithm is proposed to obtain local motions and then global affine motion. In the experimental results, we demonstrate that our proposed algorithm can handle the real-time detection of common object, small object, multiple objects, the objects in low-contrast environment, and the object in zooming camera.

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Directional Wigner-Ville Distribution and Its Application for Rotating- Machinery Condition Monitoring

  • Kim, Dong-Wan;Ha, Jae-Hong;Shin, Hae-Gon;Lee, Yoon-Hee;Kim, Young-Baik
    • Proceedings of the Korean Nuclear Society Conference
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    • 1996.05a
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    • pp.587-593
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    • 1996
  • Vibration analysis is one of the most powerful tools available for the detection and isolation of incipient faults in mechanical systems. The methods of vibration analysis in use today and under continuous study are broad band vibration monitoring, time domain analysis, and frequency domain analysis. In recent years, great interest has been generated concerning the use of time-frequency representation and its application for a machinery diagnostics and condition monitoring system. The objective of the research described in this paper was to develop a new diagnostic tool for the rotating machinery. This paper introduces a new time-frequency representation, Directional Wigner-Ville Distribution, which analyses the time- frequency structure of the rotating machinery vibration.

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A Study on Site Application Techniques for Insulation Reliability of Rotating Machine (고압회전기 절연열화진단의 현장적용기술연구)

  • Kim, K.Y.;Jo, K.H.;Kim, T.S.;Han, S.O.;Lee, H.S.
    • Proceedings of the KIEE Conference
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    • 1991.07a
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    • pp.286-291
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    • 1991
  • Most of the failures of rotating machine are stator coil insulation failures. The insulation diagnostic testing for high voltage motors and generators are only megger test and P. I Test which is applied DC voltage until now. But it was impossible to judge insulation deterioration status of high voltage rotating machinery by above testing. In other words, even though the megger measurement values are fairly high, they used to be failed from time to time. Therefore in order to excute reliable and detailed diagnosis of insulation deterioration for rotating machinery, the tangent delta test, the alternating current test and the partial discharge test shall be applied to the insulation diagnostic testing on site.

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Vibration suppression of rotating blade with piezocomposite materials (Piezocomposite 재료를 사용한 회전하는 블레이드의 진동억제)

  • Choi Seung-Chan;Kim Ji-Hwan
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.10a
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    • pp.282-285
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    • 2004
  • The main purpose of this study is the vibration suppression of rotating composite blade containing distributed piezoelectric sensors and actuators. The blade is modeled by thin-walled, single cell composite beam including the warping function, centrifugal force, Coriolis acceleration and piezoelectric effect. Further, the numerical study is performed m ing finite element method. The vibration of composite rotor is suppressed by piezocomposite actuators and PVDF sensors that are embedded between composite layers. A velocity feedback control algorithm coupling the direct and converse piezoelectric effect is used to actively control the' dynamic response of an integrated structure through a closed control loop. Responses of the rotating blade are investigated. Newmark time integration method is used to calculate the time response of the model. In the numerical simulation, the effect of parameters such as rotating speed, fiber orientation of the blade and size of actuators are studied in detail.

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Dynamics of a Rotating Cantilever Beam Near Its Critical Angular Speed (임계각속도 주변에서의 회전 외팔보의 동역학)

  • Choe, Chang-Min;Yu, Hong-Hui
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.5 s.176
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    • pp.1231-1237
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    • 2000
  • Dynamics of a rotating cantilever beam near its critical angular speed is investigated in this paper. The external, force is idealized as a periodic function which has the same period as the rotati ng frequency of the beam. The equations of motion are derived and transformed into a dimensionless form. A prescribed spin-up motion is employed for the rotating motion. Numerical study shows that the steady state and the transient responses of the beam are affected by the spin-up time constant and there exists a time constant at which the maximum transient response becomes minimum.

Numerical analysis on two-dimensional vortex merger (이차원 와류 병합에 대한 수치적 연구)

  • Park, Sanghyun;Sheen, DongJin;Chang, Kyoungsik;Kwag, DongGi
    • Journal of Aerospace System Engineering
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    • v.10 no.1
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    • pp.1-7
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    • 2016
  • During flight of the aircraft, the vortex merging phenomenon appears under the certain condition between co-rotating vortices which were generated at the wing tip and lifting-surface. And then these merged vortices at both sides show counter-rotating pattern to affect on the downstream of the aircraft. In this paper, the numerical simulations are conducted assuming this phenomenon in two-dimensional co-rotating or counter-rotating vortices pairs. Two-dimensional incompressible Navier-Stokes equations were converted into Vorticity-Streamfunction form and the Galerkin spectral method was adopted. The third order Runge-Kutta method was used for time integration. The effects on the vortex merger and degree of vortex merger were investigated according to time, Reynolds number, and changes in the distance between two vortices.

Off-Line PD Diagnosis for Stator Winding of Rotating Machines Using a UWB Sensor

  • Lwin, Kyaw-Soe;Park, Noh-Joon;Kim, Hee-Dong;Ju, Young-Ho;Park, Dae-Hee
    • Journal of Electrical Engineering and Technology
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    • v.3 no.2
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    • pp.263-270
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    • 2008
  • We studied partial discharge detection by sensing electromagnetic waves emitted from the partial discharge source in an HV Rotating Machine using a UWB sensor. In this study, we design a new type of compact low frequency UWB sensor based on micro-strip technology. We also perform many experiments of offline and dismantled testing compared with the existing HFCT on stator winding of the HV generator. We mention the detailed design of a new compact UWB sensor along with the time domain PRPD pattern and frequency domain results of partial discharge in the stator winding of a 6.6kV rotating machine by offline testing performed in a laboratory.

Dynamic Characteristics of Rotating Composite Cantilever Beam with a Breathing Crack (Breathing Crack이 있는 회전하는 복합재료 보의 동적 특성에 관한 연구)

  • Kim, Sung-Soo;Kim, Ji-Hwan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.11a
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    • pp.527-533
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    • 2000
  • It is investigated that the characteristics of rotating cantilevered composite beam with a breathing crack. In the present study, the crack is modeled as a breathing crack which opens and closes with the motion of the unidirectional graphite-fiber reinforced polyimide beam. For the finite element analysis, the cracked element is modelled by the local flexibility matrix calculated on the basis of fracture mechanics using Castiligano theorem. Rotating beam is considered only transverse bending motion so that the element includes two degrees of freedom per node such as the transverse deflection and slope. The time history and frequency response function of the beam with a breathing crack are studied by Newmark direct time integration method and FFT(Fast Fourier Transform)simulation. Effects of various parameters such as the crack depths, crack locations, ply angles, volume fraction ratios, and rotating speeds of the beam are also studied. Numerical results indicate that it is more reliable to be modelled as a breathing crack than an open crack.

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