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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society for Noise and Vibration Engineering
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Journal DOI :
The Korean Society for Noise and Vibration Engineering
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Volume & Issues
Volume 12, Issue 12 - Dec 2002
Volume 12, Issue 11 - Nov 2002
Volume 12, Issue 10 - Oct 2002
Volume 12, Issue 9 - Sep 2002
Volume 12, Issue 8 - Aug 2002
Volume 12, Issue 7 - Jul 2002
Volume 12, Issue 6 - Jun 2002
Volume 12, Issue 5 - May 2002
Volume 12, Issue 4 - Apr 2002
Volume 12, Issue 3 - Mar 2002
Volume 12, Issue 2 - Feb 2002
Volume 12, Issue 1 - Jan 2002
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Multi-modal Vibration Control of Intelligent Laminated Composite Plates Using System Identification and Optimal Control
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 1, 2002, Pages 5~11
DOI : 10.5050/KSNVN.2002.12.1.005
Active vibration control of intelligent laminated composite plates is performed experimental1y Laminated composite place is modeled by the system identification method. For the system identification process, the laminated composite place is excited by two piezoelectric actuators with PRBS signals. At the same time, the displacement of the laminated composite plate is measured by a gap sensor. From these excited PRBS signals and the measured displacement sequence, system parameters of the laminated composite plate are estimated using a recursive prediction error method. Model of the laminated composite plate with two piezoeletric actuators is assumed to be the form of ARMAX. From the estimated ARHMAX model, a state space equation of the observable canonical form is obtained. With this state space equation, a controller and an observer for active vibration control is designed using the optimal control method. Controller and observer are implemented on a digital system. Experiments on the vibration control are Performed with changing the outer layer fiber orientation of intelligent composite plates.
fictive Noise Control of Enclosed Sound Field Using LQR Controller
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 1, 2002, Pages 12~20
DOI : 10.5050/KSNVN.2002.12.1.012
To control the noise of an enclosed sound field, we built a state space model using the acoustic modal parameter description. Using the state space model, we can investigate the controllability and observability, and find an appropriate position of control speaker and microphone to control sound field of the enclosed space. We implemented LQR(linear quadratic regulator) controller and reduced order observer to reduce the first acoustic mode. Experiments showed satisfactory results of 4∼10 dB reduction of magnitude of the first acoustic mode, and support the feasibility of the proposed scheme to lightly damped acoustic field.
Stability Analysis of Transverse Vibration of a Spinning Disk with Speed Fluctuation
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 1, 2002, Pages 21~28
DOI : 10.5050/KSNVN.2002.12.1.021
This paper intends to investigate the effects of speed fluctuation caused by the cogging torque in permanent magnetic motors on the stability of the transverse vibration for a spinning disk. Based on the Kirchhoff\`s plate theory and the assumed mode methods, a set of discretized equations of motion were derived for an annular disk rotating with a harmonically varying speed. Then, a perturbation method using the multiple time scales was employed and stability boundaries were determined explicitly in terms of the magnitude and frequency of speed fluctuation, a nominal sped and the modal characteristics of the disk. It is found that parametric resonance occurs at several speed ranges and a single mode or a combination of two modes are involved to cause instability. It is also observed that unstable regions become broadened as the spinning speed increases or two modes are combined in parametric instability. As numerical simulations, stability analysis of a conventional CD-ROM drive was performed. Results of this work can e used as guidelines for motor design and operations with low vibration.
Development of a Dynamic Analysis Program for Tracked Vehicles
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 1, 2002, Pages 29~35
DOI : 10.5050/KSNVN.2002.12.1.029
A simulation program for vehicle dynamic analysis was developed. The Cartesisn coordinate system was used for translational motion and the Euler angle system was used for rotational motion. A three dimensional multi-wheeled vehicle model and equations of motion were derived. Also static equilibrium analysis was added for initial vehicle condition setting. The program user can describe the exact characteristics of suspension spring force and damping force in the user subroutine. A wheel-ground contact model which represents geometrical effect was developed. Two cases of simulation for 16 D.O.F. vehicle model were conducted to validate the developed program by comparing the simulation results with the experimental data.
A Study on the Chattering Phenomena of a Check Valve
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 1, 2002, Pages 36~41
DOI : 10.5050/KSNVN.2002.12.1.036
The cause and the elimination method for the chattering phenomena were investigated in a check valve attached to the exit of an auxiliary cooling water pump in a Korean nuclear powerplant. From the site experiment and the numerical calculation, the incident angle of the disk was so small that it was not able to produce the sufficient lifting force to overcome the gravitational component of the disk weight. Moreover, it turned out that the installation position was not symmetric for the secondary vortical flow generated inside the elbow so that the flow structure had strongly unstable flow characteristics. From this study, the tapping noise and the chattering phenomena were eliminated exactly by changing the incidence angle of the valve disk and the installation position of the calve body.
A Numerical Study on the Generation of Aeroacoustic Sound from Sirocco Fans
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 1, 2002, Pages 42~47
DOI : 10.5050/KSNVN.2002.12.1.042
Sirocco fans are widely used in HVAC and air conditioning systems, and the noise generated by these machines causes one of the most serious problems. In general, the sirocco fan noise is often dominated by tones at BPF(blade passage frequency) and broadband noise. However, only a few researches have been carried out on predicting the aeroacoustic noise because of the difficulty in obtaining detailed information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a sirocco fan. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated by the unsteady Bernoulli equation. Lowson\`s method is used to predict the acoustic source. Reasonable results are obtained not only fur the tonal noise but also far the amplitudes of the broadband noise. Acoustic pressure is proportional to (Ω)2.3, which is the similar value with the measured data.
A Study on the Characteristics of the Impulse Wave Discharged from the Exit of a Pipe
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 1, 2002, Pages 48~56
DOI : 10.5050/KSNVN.2002.12.1.048
A computational work of the impulse wave which is discharged from the open end of a pipe is compared to the Lighthill\`s aeroacoustics theory. The second-order total variation diminishing(TVD) scheme is employed to solve the axisymmetric, compressible, unsteady Euler equations. The relationship between the initial compressure wave form and the resulting impulse wave is characterized in terms of the peak pressure. The overpressure, pressure gradient and wavelength of the initial compression wave are changed to investigate the influence of the initial compressure wave form on the peak pressure of impulse wave. The results obtained show that for the initial compression wave of a large wavelength and small pressure gradient the peak pressure of the impulse wave depends upon the wavelength and pressure gradient of compression wave, but for the initial compression wave of a short wavelength and large pressure gradient the peak pressure of the impulse wave is almost constant regardless of the wavelength and pressure gradient of compression wave. The peak pressure of the impulse wave is increased with an increase in the overpressure of the initial compression wave. The results from the numerical ana1ysis are well compared to the results from the aeroacoutics theory with a food agreement.
Bifurcation Analysis of a Non-linear Hysteretic Oscillating System
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 1, 2002, Pages 57~64
DOI : 10.5050/KSNVN.2002.12.1.057
Three kinds of viscoelastic damper model, which has a non-linear spring as an element is studied analytically and numerically The behavior of the damper model shows non-linear hysteresis curves which is qualitatively similar to those of real viscoelastic materials. The motion is governed by a non-linear constitutive equation and an additional equation of motion. Harmonic balance method is applied to get analytical solutions of the system. The frequency-response curves sallow that multiple solutions co-exist and that the jump phenomena can occur. In addition, it is shown that separate solution branch exists and that it can merge with the primary response curve. Saddle-node bifurcation sets explain the occurrences of such non-linear Phenomena.
A Study on the Vibrational Reduction Evaluation and the Relative Displacement in the External Vibration of Precision Measuring System
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 1, 2002, Pages 65~72
DOI : 10.5050/KSNVN.2002.12.1.065
Generally, there are laser operating equipments( aligner, stepper) and electronic microscope( SEM, TEM) as a high precision manufacturing and inspection equipment in semiconductor production companies, precision examination and measuring laboratories. Mostly, these equipments are characterized by projection and target part. The relative displacements between projection and target part are dominant roles in vibrational problem in these precision equipments. These relative displacements are determined by the position of incoming vibration and the difference of vibration response in projection and target part. In this study, the allowable vibrational limits are suggested and the vibrational reduction plans are proposed by measurement and analysis of vibration phenomenon in the Clean Room in PDP(plasma display panel) production building. The vibration performance is
4-pole Lorentz Force Type Self-bearing Motor with a New Winding Configuration
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 1, 2002, Pages 73~81
DOI : 10.5050/KSNVN.2002.12.1.073
This paper introduces a four-Pole Lorentz force type self-bearing motor in which a new winding configuration is proposed to enable the sing1e winding to function both as a synchronous PM motor and as a magnetic bearing. The Lorentz force type has some good points such as the linearity of control force, freedom from flux saturation, and high efficiency, unlike conventional self-bearing motors using a reluctance force. And also, compared with the previously proposed eight-pole type, this four-pole self-bearing motor is more profitable for high rotational speed. In this paper, mathematical expressions of torque and radial force in the proposed self-bearing motor are derived to show that they can be separately controlled regardless of rotational speed and time. For verification of the theory, a prototype is made, where a ring-shape outer rotor is actively controlled in two radial directions while the other motions are passively stable supposing the radial stability. Through some experiments. it is shown that the proposed scheme can provide high capability and feasibility for a small high-speed self-bearing motor.
Free Vibrations of Horizontally Curved Beams with Transient Curve
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 1, 2002, Pages 82~88
DOI : 10.5050/KSNVN.2002.12.1.082
This paper deals with the free vibrations of horizontally curved beams with transition curve. Based on the dynamic equilibrium equations of a curved beam element subjected to the stress resultants and inertia forces, the governing differential equations are derived for the out-of-plane vibration of curved beam wish variable curvature. This equations are applied to the beam having transition curve in which the third parabolic curve is chosen in this study. The differential equations are solved by the numerical procedures for calculating the natural frequencies. As the numerical results, the various parametric studies effecting on natural frequencies are investigated and its results are presented in tables and figures. Also the laboratory scaled experiments were conducted for verifying the theories developed herein.