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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 16, Issue 12 - Dec 2006
Volume 16, Issue 11 - Nov 2006
Volume 16, Issue 10 - Oct 2006
Volume 16, Issue 9 - Sep 2006
Volume 16, Issue 8 - Aug 2006
Volume 16, Issue 7 - Jul 2006
Volume 16, Issue 6 - Jun 2006
Volume 16, Issue 5 - May 2006
Volume 16, Issue 4 - Apr 2006
Volume 16, Issue 3 - Mar 2006
Volume 16, Issue 2 - Feb 2006
Volume 16, Issue 1 - Jan 2006
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Hysteresis Investigation of Magnetorheological Fluid Using Preisach Model
Han, Y.M. ; Lim, K.H. ; Choi, S.B. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 3~11
DOI : 10.5050/KSNVN.2006.16.1.003
This paper presents a new approach for hysteresis modeling of a magnetorheological (MR) fluid. The field-dependent hysteresis of MR fluid is investigated using the Preisach model. The commercial MR product (MRF-132LD, Lord Corporation) is employed. Its field-dependent shear stress is then obtained using a rheometer (MCR 300, Physica). In order to show the applicability of the Preisach model to the MR fluid, two significant properties; the minor loop property and the wiping-out. property are experimentally examined. Subsequently, the Preisach model for the MR fluid is identified using experimental first order descending (FOD) curves in discrete manner. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one. In addition, the hysteresis model proposed in this work is compared to Bingham model.
Characterization and Detection of a Free-falling State of a Mobile HDD Using the Electromechanical Analysis in a Rotating Spindle System
Park, Sang-Jin ; Jang, Gun-Hee ; Kim, Cheol-Soon ; Han, Jae-Hyuk ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 12~18
DOI : 10.5050/KSNVN.2006.16.1.012
This research investigates the electromechanical characteristics of a spindle motor in a free-falling mobile hard disk drive before unexpected shock. Electromechanical simulation includes a time-stepping finite element analysis of the magnetic field in a speed controlled brushless DC motor and dynamic analysis of the stationary and rotating part linked by the fluid dynamic bearing under the free-falling condition. Analysis results show that the dynamic characteristics of the rotating spindle system during free-falling state have an effect on the relative motion between the stationary and rotating part of HDD. It results from the variation of reaction force in the bearing area due to the gravity force exerted on the rotating part of HDD, and the free-falling condition can be detected by observing the signal of the spindle motor and disk-head interface without using an accelerometer.
Stability Assessment of an Adjacent Ground Storage Tank by Blast-induced Vibration
Jong, Yong-Hun ; Lee, Chung-In ; Choi, Yong-Kun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 19~26
DOI : 10.5050/KSNVN.2006.16.1.019
The test blasts were carried out by detonating some single blastholes at two upper sites of the underground storage cavern for the crude oil. One was performed at the entrance site of the construction tunnel and the other at the middle area of the underground storage cavern. Based on the blast-induced nitration measured by the test blasts, we suggested the propagation equations of blasting vibration that were capable of estimating the peak particle velocity. In addition, in order to assess the stability of the adjacent ground storage tank, we did the frequency analysis and the response spectrum analysis with the particle velocity-time history and the particle acceleration-time history that were measured by the test blast carried out on the entrance site of the construction tunnel. In result, it was predicted that the displacement on the highest part of the tank shell was less than the allowable displacement.
Fault Diagnosis for Rotating Machine Using Feature Extraction and Minimum Detection Error Algorithm
Chong, Ui-pil ; Cho, Sang-jin ; Lee, Jae-yeal ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 27~33
DOI : 10.5050/KSNVN.2006.16.1.027
Fault diagnosis and condition monitoring for rotating machines are important for efficiency and accident prevention. The process of fault diagnosis is to extract the feature of signals and to classify each state. Conventionally, fault diagnosis has been developed by combining signal processing techniques for spectral analysis and pattern recognition, however these methods are not able to diagnose correctly for certain rotating machines and some faulty phenomena. In this paper, we add a minimum detection error algorithm to the previous method to reduce detection error rate. Vibration signals of the induction motor are measured and divided into subband signals. Each subband signal is processed to obtain the RMS, standard deviation and the statistic data for constructing the feature extraction vectors. We make a study of the fault diagnosis system that the feature extraction vectors are applied to K-means clustering algorithm and minimum detection error algorithm.
Effect of the Measuring Method of Reverberation Time Using Impulse Response Method on the Normalized Impact Sound Pressure Level
Lee, J.W. ; Kwon, Y.P. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 34~39
DOI : 10.5050/KSNVN.2006.16.1.034
For the evaluation of the normalized impact sound pressure level, the reverberation time of the receiving room should be measured. This paper deals with the effect of the time constant of FFT analyzer and the measuring points on reverberation time. It is found that the time constant should be in the range between 10 ms and 35 ms. While the effect of measuring points on the reverberation time is significant when the bandwidth is narrow it is negligible in the evaluation of the normalized impact sound pressure level.
Disturbance Analysis in an Optical Disk Drive Using Model Based Disturbance Observer and Waterfall Technique
Choi, Jin-Young ; Lee, Kwang-Hyun ; Jun, Hong-Gul ; Lee, Moon-Noh ; Yang, Hyun Seok ; Park, No-Cheol ; Park, Young-Pil ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 40~49
DOI : 10.5050/KSNVN.2006.16.1.040
A novel disturbance measurement method, model based disturbance observer (MBDO) for optical disk drives (ODDs), is proposed and the disturbance analysis using the proposed method is performed under various conditions. In ODDs, the quantitative and qualitative analysis for the generated disturbance during normal operation is very important to successful servo loop design. However, the disturbance measurement is difficult, and high precision measurement is necessary. Furthermore, the conventional disturbance measurement method using a LDV (laser Doppler vibrometer) has many difficulties in eccentricity direction due to the vertical movement of an optical disk. To solve this problem, the MBDO is proposed. First, the relationship between the servo loop for ODDs and the generated disturbance are briefly reviewed. Second, the principle of the MBDO is introduced, and the disturbance measurement results, which are measured by the MBDO and a LDV, are compared. In these experiments, test DVD-ROM disks are used to generate quantitative/qualitative disturbance. Then, the disturbance analysis under various conditions is performed using waterfall technique. This technique clearly shows the disturbance trend from the inner part of an optical disk to the outer part of it. Finally, the various disturbances measurement results are summarized and some remarks for it are commented.
Ramp Load/Unload Velocity Control of VCM Using BEMF in HDD
Jeong, Jun ; Kim, Tae-Soo ; Kang, Tae-Sik ; Jung, Kwang-Jo ; Lee, Chul-Woo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 50~56
DOI : 10.5050/KSNVN.2006.16.1.050
Since most of small form-factor drives have a load/unload mechanism and the flying height of the head is getting lower as the capacity of disk drives increases, the load/unload velocity becomes one of the important factors to ensure the reliability of the load/unload mechanism. To control the load/unload velocity accurately, velocity sensing is essential. In this paper, we introduce a very practical method that acquires the load/unload velocity from the back electromotive force (BEMF) of a voice coil motor (VCM) and propose a calibration method for measuring the BEMF from a given circuit. Moreover, the effect of calibration error and temperature variation on the measurement of BEMF is shown by simulation. Then, this present method is applied to the load/unload velocity controller and is verified from the experimental result.
Modeling for the Natural Vibration Analysis of a Rotating Thin Ring
Kim, Chang-Boo ; Kim, Sehee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 57~65
DOI : 10.5050/KSNVN.2006.16.1.057
In this paper, we present the principle of virtual work, from which the exact non-linear equations of motion of a rotating ring can be derived, by using the theory of finite deformation. For a thin ring of which the effect of variation in curvature across the cross-section is neglected, the radial displacement and the extensional stress are determined from the principle of virtual work at the steady state where the ring is rotating with a constant angular velocity. And also we formulate systematically the governing equations concerned to the in-plane vibrations and the out-of-plane vibrations at the disturbed state by using the principle of virtual work which is expressed with the disturbed displacements about the steady state. The formulated governing equations are classified by four models along the cases of considering or neglecting all or partly the secondary effects of flexural shear, rotary inertia, circumferential extension, and twist inertia. The natural vibrations of thin rings are analyzed, and its results are compared and discussed.
Analysis of the Acoustic Evaluation Factors Depending on the in Performance Types Multi-purpose Halls
Park, Hyeon-Ku ; Kim, Hang ; Kim, Sun-Woo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 66~74
DOI : 10.5050/KSNVN.2006.16.1.066
This study aimed to evaluate the room acoustical performances of multi-purpose halls, surveying the architectural features and analysing the acoustical characteristics by measurements. In addition, adjectives appropriate for the evaluation of the room acoustical performance in multi-purpose halls were determined through the method of questionnaire survey and subjective evaluation through psycho-acoustic experiment. The results from the experiment were analysed by the correlation analysis and the factor analysis, consequently useful adjectives for the evaluation of acoustical performances in multi-purpose halls were determined depending on the types of performance.
Experimental Study on the Electrostatic Discharge in the HDD Spindle System Using Fluid Dynamic Bearings
Kang, Min-Gu ; Jang, Gun-Hee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 75~80
DOI : 10.5050/KSNVN.2006.16.1.075
This paper introduces the mechanism of the ESD(electrostatic discharge) in the HDD spindle system using FDBs(fluid dynamic bearings). When a HDD(hard disk drive) spindle system is rotating, triboelectric charging occurs in the FDBs through the friction between the lubricant and the rotating shaft or between the lubricant and stationary sleeve. And this electrostatic charge is accumulated in the rotating parts of the HDD spindle system because they are insulated from the ground by the lubricant. This research shows experimentally that the behavior of electric charge and discharge in the FDB spindle system is the same as that of a capacitor. It also measures the electrostatic voltage difference between the rotating and stationary parts in the FDB spindle system due to the change of humidity, supporting load and motor speed. This research shows that the control of ESD is required in the HDD spindle system using FDBs, because the electrostatic charge accumulated in the FDB spindle system may cause the breakdown damage of the GMR head and data loss consequently.
Development of Directional Digital Hearing Aid Performance Testing System
Jang, Soon-Suck ; Kwon, You-Jung ; Lee, Je-Hyeong ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 81~88
DOI : 10.5050/KSNVN.2006.16.1.081
The most recent trend on digital hearing aid is to increase the ratio of signal to noise by directivity or to develop noise reduction algorithm inside DSP IC chip. This paper designed, fabricated and tested a digital hearing aid directivity testing device in which a micro-mouse-like the stepping motor with a speaker rotates around an examinant. Both ears of the examinant were fixed with ITE hearing aids in order to respond to receiving sound. The experimental results were compared with those of a boundary element method program for verification. The diameter of the directivity testing device was 2 m and the micro-mouse was precisely controlled by PICBASIC micro processor.
Variation in the Vibration Characteristics of a Piezoelectric Transducer due to Pre-pressure
Kim, Dae-Seung ; Kim, Jin-Oh ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 1, 2006, Pages 89~100
DOI : 10.5050/KSNVN.2006.16.1.089
This paper presents an analytical approach to describe the variation in the vibration characteristics such as the natural frequency of a piezoelectric transducer under static pre-pressure. The transducer considered in this paper is a bolt-clamped Langevin-type transducer, which consists of a couple of piezoelectric discs, a couple of metal blocks for added mass effect, and a bolt to tighten them. A new analysis model for the transducer has been developed by taking into account the contact area between the piezoelectric ceramic disc and the metal block. The variation of the resonance frequency due to the pre-pressure has been calculated and compared with measured results reported earlier