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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 19, Issue 12 - Dec 2009
Volume 19, Issue 11 - Nov 2009
Volume 19, Issue 10 - Oct 2009
Volume 19, Issue 9 - Sep 2009
Volume 19, Issue 8 - Aug 2009
Volume 19, Issue 7 - Jul 2009
Volume 19, Issue 6 - Jun 2009
Volume 19, Issue 5 - May 2009
Volume 19, Issue 4 - Apr 2009
Volume 19, Issue 3 - Mar 2009
Volume 19, Issue 2 - Feb 2009
Volume 19, Issue 1 - Jan 2009
Selecting the target year
Effect of the Number of Slots on the Acoustic Noise from BLDC Motors
Kwon, Joong-Hak ; Kim, Kwang-Suk ; Lee, Chang-Min ; Hwang, Sang-Moon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 759~763
DOI : 10.5050/KSNVN.2009.19.8.759
The goal of this study is to examine the effect of the number of slots on the noise from BLDC motors. To this end, the number of poles was fixed to 4 and the number of the slots was set to 6 or 24 before noise was measured. Motors having different numbers of slots showed clear differences in noise. Cogging torque, torque ripple and normal local force were interpreted, analyzed and compared to determine the reason for the differences. To determine the cause of the noise, cogging torque, torque ripple and normal local force were calculated, which are representative noise sources of BLDC motors, and FFT was performed to analyze their frequency components(harmonics). The results show that torque ripple and normal local force were the dominant factors in the noise difference between the 6-slot and 24-pole motors. As the number of the slots increased, the number of harmonics decreased and their amplitude of harmonic were reduced, which was attributed as the reason for the noise differences.
Fluid/Structure Coupled Analysis of 3D Turbine Blade Considering Stator-rotor Interaction
Kim, Yu-Sung ; Kim, Dong-Hyun ; Kim, Yo-Han ; Park, Oung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 764~772
DOI : 10.5050/KSNVN.2009.19.8.764
In this study, fluid/structure coupled analyses have been conducted for 3-D stator and rotor configuration. Advanced computational analysis system based on computational fluid dynamics(CFD) and computational structural dynamics(CSD) has been developed in order to investigate fluid/structure responses of general stator-rotor configurations. To solve the fluid/structure coupled problems, fluid domains are modeled using the structural grid system with dynamic moving and local deforming techniques. Reynolds-averaged Navier-Stokes equations with Spalart-Allmaras(S-A) and SST
turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3-D turbine blades for fluid-structure interaction(FSI) problems. Detailed fluid/structure analysis responses for stator-rotor interaction flow conditions are presented to show the physical performance and flow characteristics.
Estimation of Dynamic Load of the Utility in Building by TPA Method
Jeong, Min-Ki ; Lee, Seong-Soo ; Kim, Yong-Ku ; Ahn, Sang-Kyung ; Lee, Sang-Yeop ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 773~780
DOI : 10.5050/KSNVN.2009.19.8.773
The facility equipments generate dynamic force on building floor and the force can be measured with force transducer. However, this method depends on the measuring capacity or range of sensor, or mounts installation condition of equipments. Because of this restricting condition on force measuring system, this paper suggests a indirect method, the TPA(transfer path analysis) method, that produces a closely approximate dynamic force of equipments. This method calculates the dynamic force by using transfer response function. Firstly, the calculated dynamic force of impact load and continuous load was respectively compared with the sensor-measured value to examine the accuracy of TPA method. After that, the dynamic force and response induced by large facility equipments - a cooling tower, AHU and a large ventilator - were calculated by TPA method and the validity of these value were examined.
Dynamic Characteristics of ALA and Active Vibration Control Experiment
Lee, Han-Dong ; Kwak, Moon-K. ; Kim, Jeong-Hoon ; Song, Yoon-Chul ; Shim, Jae-Ho ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 781~787
DOI : 10.5050/KSNVN.2009.19.8.781
This research is concerned with the application of the active linear actuator to the active vibration control of structure. The active linear actuator will be mounted on the sub-frame so that it can cancel the excitation transferred from the engine. Accelerometer mounted on the sub-frame detects the vibration and its signal is fed into the DSP controller where the control algorithm is installed. The output of the DSP controller is connected to the driver which amplifies the DSP output. In general, the pulse width modulation power amplifier is used to drive the voice-coil type actuator. This study shows the dynamic characteristics of the active linear actuator and active vibration control experimental results.
A HDD Latch Design Using Electro-magnetic Force of VCM Actuators
Kim, Kyung-Ho ; Oh, Dong-Ho ; Shin, Bu-Hyun ; Lee, Seung-Yop ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 788~794
DOI : 10.5050/KSNVN.2009.19.8.788
Various types of latch designs for hard disk drives using load/unload mechanism have been introduced to protect undesired release motions of a voice coil motor(VCM) actuator from sudden disturbances. Recently, various inertia-type latches have been widely used because locking performance is better than that of other types of latch. However there has been a limit in the inertia type in order to guarantee perfect latch and unlatch operations because of changes in latch/unlatch conditions due to mechanical tolerance and temperature-dependent friction. In this paper, a reliable and robust magnetic latch mechanism is proposed through only simple modifications of coil and yoke shapes in order to overcome the mechanical limit of current inertia-type latches. This new magnetic latch does not have only a simple structure but it also ensures reliable operations and anti-shock performance. The operating mechanism of the proposed latch is theoretically analyzed and optimally designed using an electromagnetic simulation.
Design and Control of MR Fan Clutch for Automotive Application
Kim, Eun-Seok ; Sohn, Jung-Woo ; Choi, Seung-Bok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 795~801
DOI : 10.5050/KSNVN.2009.19.8.795
This paper presents an optimal design of a magnetorheological(MR) fan clutch based on finite element analysis and also presents torque control of engine cooling fan using a sliding mode control. The MR fan clutch is constrained in a specific volume and the optimization problem identifies the geometric dimension of the fan clutch that minimizes an objective function. The objective function for the optimization problem is determined based on the solution of the magnetic circuit of the initially designed clutch. Under consideration of spatial limitation, design parameters are optimally determined using finite element analysis. After describing the configuration of the MR fan clutch, the viscous torque and controllable torque are obtained on the basis of the Bingham model of MR fluid. Then, a sliding mode controller is designed to control the torque of the fan clutch according to engine room temperature and control performance is evaluated through computer simulation.
Experimental Study for Construction Equipment's Cabin Noise Control
Lee, Tae-Kyoung ; Joo, Won-Ho ; Bae, Jong-Gug ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 802~808
DOI : 10.5050/KSNVN.2009.19.8.802
In this paper, the experimental study on the identification of noise sources and noise transmission paths was carried out for the cabin noise control of construction equipment. In order to investigate noise and vibration characteristics of cabin structure, sound absorption, transmission, and radiation tests were performed using cabin assembly models. The noise/vibration source levels were obtained from the real cabins of wheel loader and excavator. Using transfer functions of cabins and real cabins' source data, cabin noise was decomposed into airborne and structureborne noise transmissions. Finally noise sources and major transmission paths were successfully identified for wheel loader and excavator's cabins.
Localization of Acoustic Sources on Wind Turbine by Using Beam-forming Techniques
Lee, Gwang-Se ; Shin, Su-Hyun ; Cheong, Cheol-Ung ; Jung, Sung-Soo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 809~815
DOI : 10.5050/KSNVN.2009.19.8.809
The previous work(Cheong et al., 2006) where the characteristics of acoustic emissions of wind turbines has been investigated according to the methods of power regulation, has showed that the acoustic power of wind turbine using the stall control for power regulation is more correlated with the wind speed than that using the pitch control. In this paper, basically extending this work, the noise generation characteristics of large modern upwind wind turbines are experimentally indentified according to the power regulation methods. To investigate the noise generation mechanisms, the distribution of noise sources in the rotor plane is measured by using the beam-forming measurement system(B&K 7768, 7752, WA0890) consisting of 48 microphones. The array results for the 660 kW wind turbine show that all noise is produced during the downward movement of the blades. This result show good agreement with the theoretical result using the empirical formula with the parameters: the convective amplification; trailing edge noise directivity; flow-speed dependence. This agreement implies that the trailing edge noise is dominant over the whole frequency range of the noise from the 660 kW wind turbine using the pitch control for power regulation.
Bearing Faults Localization of a Moving Vehicle by Using a Moving Frame Acoustic Holography
Jeon, Jong-Hoon ; Park, Choon-Su ; Kim, Yang-Hann ; Koh, Hyo-In ; You, Won-Hee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 816~827
DOI : 10.5050/KSNVN.2009.19.8.816
This paper deals with a bearing faults localization technique based on holographic approach by visualizing sound radiated from the faults. The main idea stems from the phenomenon that bearing faults in a moving vehicle generate impulsive sound. To visualize fault signal from the moving vehicle, we can use the moving frame acoustic holography [Kwon, H.-S. and Kim, Y.-H., 1998, "Moving Frame Technique for Planar Acoustic Holography," J. Acoust. Soc. Am. Vol. 103, No. 4, pp. 1734
1741]. However, it is not easy to localize faults only by applying the method. This is because the microphone array measures noise(for example, noise from other parts of the vehicle and the wind noise) as well as the fault signal while the vehicle passes by the array. To reduce the effect of noise, we propose two ideas which utilize the characteristics of fault signal. The first one is to average holograms for several frequencies to reduce the random noise. The second one is to apply the partial field decomposition algorithm [Nam, K.-U., Kim, Y.-H., 2004, "A Partial Field Decomposition Algorithm and Its Examples for Near-field Acoustic Holography," J. of Acoust. Soc. Am. Vol. 116, No. 1, pp. 172
185] to the moving source, which can separate the fault signal and noise. Basic theory of those methods is introduced and how they can be applied to localize bearing faults is demonstrated. Experimental results via a miniature vehicle showed how well the proposed method finds out the location of source in practice.
Free Vibration Analysis of Stiffened Tapered Thick Plates with Concentrated Masses
Lee, Yong-Soo ; Kim, Il-Jung ; Oh, Soog-Kyoung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 828~837
DOI : 10.5050/KSNVN.2009.19.8.828
Recently, as high-rise buildings increase steeply, sub-structures of them are often supported on elastic foundation(in a case of pasternak foundation or winkler foundation). And there are many machines in sub-structures of buildings and slabs of sub-structures are affected by vibration which they make. This paper deals with vibration of plates on elastic foundation. Machines on plates are considered as concentrated mass. This paper has the object of investigating natural frequencies of tapered thick plate on pasternak foundation by means of finite element method and providing kinetic design data for mat of building structures. Free vibration analysis that tapered thick plate with Concentrated Masses in this paper. Finite element analysis of rectangular plate is done by use of rectangular finite element with 8-nodes. In order to analysis plate which is supported on pasternak foundation. The Winkler parameter is varied with 10,
and the shear foundation parameter is 5, 10. This paper is analyzed varying thickness by taper ratio. The taper ratio is applied as 0.0, 0.25, 0.5, 0.75, 1.0. And the Concentrated Mass is applied as P1, Pc, P2 respectively.
A Study on the Improvement of Vibration Analysis of Visual Alignment System Using CAE Method
Lee, Seung-Yoon ; Kim, Sung-Rae ; Jeong, Jay-I. ; Yim, Hong-Jae ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 838~842
DOI : 10.5050/KSNVN.2009.19.8.838
Vibrational analysis is presented for a visual alignment system of nano-imprint process in this study. For a nano-imprinting equipment, the visual alignment system is one of the essential parts in order to align the mold into the target panel. For the precision alignment, the vibration from inside and outside of the vision system should be avoided, and the elimination of the vibration should be considered in the design process of the visual alignment design. In this work, vibrational characteristics for the vision system frame is analyzed and topology optimization of a frame section area is carried out. With the results of the analysis, a new frame design are suggested. Design consideration for constructing a visual alignment system in view of optimal design is also discussed.
An Experimental Determination of a Swing Check Valve Closure Time in the Main Feed Water System of a Power Plant during Shut-down Process
Suh, Jin-Sung ; Kim, Won-Min ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 843~849
DOI : 10.5050/KSNVN.2009.19.8.843
The reliable operation of a swing check valve in the main feed water system of a power plant is most essential for successful shout-down process. A failure to close the valve at proper time often leads to the instability of the main feed water system, or even to an emergency stop of the power plant. In reality it is a very difficult task to monitor the behavior of a swing check valve. Furthermore it is impossible to see the motion of the valve. In this work two measurements were carried out simultaneously to determine the precise valve closure time. The dynamic pressure measurements were made at the inlet and outlet regions of the swing check valve. The transient vibration of the valve housing in the direction of water flow was also measured, which enabled the measurement of the transient vibration of the valve housing near valve closure. By comparing the results produced from these measurements the precise valve closure time could be determined. By carrying out order tracking technique using the dynamic pressure signals and pump rpm signal, the complicated dynamic problems inside the main feed water system can be more easily dealt with. This measurement scheme might be implemented in a power plant on a real-time basis without much difficulty. If this could be implemented, valuable information essential for shut-down operations can readily be passed on to the main control room. The feasibility of this implementation was demonstrated by this experimental work.
Design Parameter of a New Type Bi-directional Damper Using a Tuned Liquid Column Damper and a Tuned Sloshing Damper
Min, Kyung-Won ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 8, 2009, Pages 850~856
DOI : 10.5050/KSNVN.2009.19.8.850
A new type bi-directional damper using a tuned liquid column damper(TLCD) and a tuned sloshing damper(TSD) is introduced in this study. Two dampers are usually needed to reduce wind-induced responses of tall buildings since they are along and across wind ones. The proposed damper has the advantage of controlling both responses with one damper. One of objectives of this study is to derive analytical dynamics to investigate coupled effects due to TLCD and TSD. Another objective is to address the effect of coupled control force due to TLCD and TSD on the dynamic characteristic of the damper based on analytical dynamics. Shaking table test is undertaken to experimentally grasp dynamic characteristics of the damper under white noise excitation. Its dynamic characteristic is expressed by the transfer function from the shaking table acceleration to the control force generated from the damper. Finally, its design parameters are identified based on the coupled dynamics, which include the mass ratio of horizontal liquid column to total liquid for a TLCD, the participation factor of the fundamental liquid sloshing for a TSD and damping ratio for both cases.