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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 14, Issue 12 - Dec 2004
Volume 14, Issue 11 - Nov 2004
Volume 14, Issue 10 - Oct 2004
Volume 14, Issue 8 - Aug 2004
Volume 14, Issue 7 - Jul 2004
Volume 14, Issue 6 - Jun 2004
Volume 14, Issue 5 - May 2004
Volume 14, Issue 4 - Apr 2004
Volume 14, Issue 9 - Mar 2004
Volume 14, Issue 3 - Mar 2004
Volume 14, Issue 2 - Feb 2004
Volume 14, Issue 1 - Jan 2004
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FVT Signal Processing for Structural Identification of Cable-stayed Bridge
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 923~929
DOI : 10.5050/KSNVN.2004.14.10.923
In this research, Forced Vibration Test(FVT) on a cable stayed bridge was conducted to examine the validity of the frequency domain pattern recognition method using signal anomaly index and artificial neuralnetwork. 7he considering structure, Samchunpo Bridge, located in Sachun-Shi, Kyungsangnam-Do, is a cable stayed bridge with the 436 meter span. The excitation force was induced by a sudden braking of a fully loaded truck. and vortical acceleration signals were acquired at 14 points. The initial 2-dimensional FE-model was developed from the design documents to prepare the training sets for the artificial neural network, and then the model calibration was performed with the field test data. As a result of the model calibration, we obtained the FFT spectrums from the model simulation, which was similar to those from the vibration test. These tests and the simulation data will be used for the structural identification using arbitrarily added masses to the bridge.
Noise Source Identification of a Car A/V System
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 930~938
DOI : 10.5050/KSNVN.2004.14.10.930
This paper presents the noise source identification of a car A/V system. There are two different kinds of noise sources noise generated by loading mechanism and rattle noise by externally forced vibration. A dynamometer has been made to produce stationary inertia to the loading mechanism of A/V system. Sound pressure spectra and sound intensity were measured by operating the dynamometer setup as various motor speeds, and the results were analyzed. A dominant rattle noise source about A/V system's components has been found by multi-dimensional spectral analysis. Residual spectrum method was applied for eliminating coherence between the vibration sources. In result, the dominant rattle noise source was identified by partial coherent output spectrum of individual vibration component.
A Design Study of Aerodynamic Noise Reduction In Centrifugal Compressor Part II . Low-noise Optimization Design
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 939~944
DOI : 10.5050/KSNVN.2004.14.10.939
The numerical methods including the performance analysis and the noise prediction of the centrifugal compressor impeller are coupled with the optimization design skill, which consists of response surface method, statistical approach, and genetic algorithm. The flow-field Inside of a centrifugal compressor is obtained numerically by solving Wavier-Stokes equations. and then the propagating noise is estimated from the distributed surface pressure by using Ffowcs Williams-Hawkings formulation. The quadratic response surface model with D-optimal 3-level factorial experimental design points is constructed to optimize the impeller geometry for the advanced centrifugal compressor. The statistical analysis shows that the quadratic model exhibits a reasonable fitting quality resulting in the impeller blade design with high performance and low far-field noise level. The influences of selected design variables, objective functions, and constraints on the impeller performance and the impeller noise are also examined as a result of the optimization process.
A Shock Damage Evaluation Study of Large Digital TV Display Modules
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 945~954
DOI : 10.5050/KSNVN.2004.14.10.945
Recently, specifications of flat display module is going to be higher definition, brightness and more wide viewing angle. On the other hand, physical thickness of those modules is forced to be slimmer and lighter. The flat display modules such as plasma or TFT-LCD employ thin crystallized panels that are normally weak to high level transient mechanical energy inputs. As a result, anti-shock performance is one of the most important design specifications of TFT-LCD modules. TFT-LCD module manufacturers and their customers like PC or TV makers perform a series of strict impact/drop test for the modules. However most of the large display module designs are generated based on engineer's own trial-error experiences. Those designs may result in disqualification from the drop/impact test during final product evaluation. A rigorous study on the impact failure of the displays is of course necessitated in order to avoid the problems. In this article, a systematic design evaluation is presented with combinations of FEM modeling and testing to support the optimal shock proof display design procedure.
Mode-decoupling Controller for Feedback Model Updating
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 955~961
DOI : 10.5050/KSNVN.2004.14.10.955
A novel concept of feedback loop design for modal test and model updating is proposed. This method uses the closed-loop natural frequency information for parameter modification to overcome the problems associated with the conventional method employing the modal sensitivity matrix. To obtain new modal information from closed-loop system, controllers should be effective in changing modal data while guaranteeing the stability of closed-loop system. But it is very hard to guarantee the stability of the closed-loop system with non-collocated sensor and actuator set. In this research, we proposed a controller called mode-decoupling controller that can change a target mode as much as the designer wants guaranteeing the stability of closed-loop system. This controller can be computed Just using measured open-loop modeshape matrix. A simulation based on time domain input/output data is performed to check the feasibility of proposed control method.
Vibrational Characteristics of an End Beam of a Freight Cal- on the Taebaek Line
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 962~967
DOI : 10.5050/KSNVN.2004.14.10.962
A bogie is the device that connects a car body and wheel sets of a rail vehicle. It is the critical component that determine:; the running safety, The bogie consists of a frame, suspensions, brakes and wheel sets. Various analyses including a numerical simulation using a finite element method, a static load test, a fatigue test, ai)d r running test should be carried out to design the bogie. However cracks have been found at some end beams of the bogies mounted on the freight cars running with the high speed. The cracks of the end beam results in deterioration of the brake performance an the running safety, A new design has been suggested to solve this problem by ROTEM company and it's performance has been tested in this paper. Numerical simulations and dynamic tests are carried out to figure out the causes of cracks in the conventional bogie, and the vibrational characteristics of the improved bogie are compared with those of the conventional one.
The Development of an Automatic Noise Inspection System of a Rotating Engine Part Using OLE
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 968~974
DOI : 10.5050/KSNVN.2004.14.10.968
Automakers have been forcing their suppliers to guarantee qualities of parts. Then, the suppliers have met the fundamental quality requirements such as dimensions and functions, but they could not sufficiently satisfy the automakers' noise requirements yet because automatic noise inspection systems were little successfully adopted In mass-production lines. This study tried to develop a system for automatically checking noise radiated from a rotating engine part and filtering parts emitting noise higher than criteria: the upper limits of a overall noise level or a noise spectrum. A commercial noise measurement system was used for measuring noise, and then the noise data was transmitted to a governing program through OLE(object, linking and embedding) functions. The governing program, belonging to a total noise inspection system managed the noise measurement and analysis. This system was successfully adapted for distinguishing bad parts according to the noise criteria.
Acoustic Characteristics of a .Silencer by Using Array Resonators
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 975~982
DOI : 10.5050/KSNVN.2004.14.10.975
Helmholtz resonator is used to reduce noise of the narrow frequency band. It has high transmission loss at its resonance frequency. The silencer that combines many resonators could control broadband noise at low frequency. To convey this rather simple idea, serial and parallel arrangement of resonators have been tested to obtain high transmission loss characteristics in the band of which are selects. Theoretical and experimental results explain these characteristics in the absence of mean flow. The change of acoustic characteristics by the resonance frequencies and resonators arrangement are explained by using the equivalent Impedance analysis that is defined in this paper. It shows that the transmission loss has a maximum value when the separation distance between each resonator is λ/4 of its wavelength.
Vibration Analysis of Rotating Structures Employing Multi-reference Frames
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 983~989
DOI : 10.5050/KSNVN.2004.14.10.983
In this paper, a modeling method for the vibration analysis of rotating structures employing multi-reference frames is presented. The geometric stiffening effect that results from centrifugal inertia force is considered. In most previous studies single reference frame has been employed for the analysis. In the present study, a modeling method employing multi-reference frames is presented, and the effects of employing multi-reference frames on the analysis accuracy are investigated through solving numerical examples.
The Dynamic Characteristics of Bolt Jointed Plates Using the Finite Element Method
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 990~998
DOI : 10.5050/KSNVN.2004.14.10.990
There have been lots of efforts to analyze the dynamic characteristics of mechanical systems. However, it is difficult the know the dynamic characteristics of mechanical systems composed of many parts with joints. Specially, in case of a bolted Joint structure, no effective modeling method has been defined to acquire dynamic characteristics of the structure using the finite element (FE) analysis. In this research, a linear dynamic model is developed for bolted feints and large interfaces using con frusta method and linear spring elements, respectively. The developed modeling method for bolted joints is verified based on the experimental result.
Analysis on the Characteristics of the Ride Comfort for High Speed Trains on the High Speed Line/conventional Line
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 999~1006
DOI : 10.5050/KSNVN.2004.14.10.999
Recently, the ride comfort problem becomes increasingly important because of today's needs for train speedup. The railway has the track irregularities which cause vibrations, such as rail joints, turnout, level crossing, transition corves and super-elevation ramps, and variations in the track level(z-axis) and the gauge(y-axis). In Korea, the service run of the high speed train has been made since the 1st of April, 2004. The commercial high-speed trains must be run on the compound lines which are composed of high-speed line and conventional line. The high speed lines in both Kyoungbu line and Honam line have 57.5％ and 33.8％, respectively In this Paper, the ride comfort has been reviewed by the various experimental methods when the high-speed trains are operated on both Kyoungbu line and Honam line. The results show that the high-speed train has no problems from the viewpoint of the comfort ride during the operation on the high speed line and conventional line.
Active Structural Acoustical Control of a Smart Panel Using Direct Velocity Feedback
Stephen J, Elliott ; Paolo, Gardonio ; Young-Sup, Lee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 1007~1014
DOI : 10.5050/KSNVN.2004.14.10.1007
This paper presents a study of low frequencies volume velocity vibration control of a smart panel in order to reduce sound transmission. A distributed piezoelectric quadratically shaped polyvinylidene fluoride (PVDF) polymer film is used as a uniform force actuator and an array of
accelerometer is used as a volume velocity sensor for the implementation of a single-input single-output control system. The theoretical and experimental study of sensor-.actuator frequency response function shows that this sensor-actuator arrangement provides a required strictly positive real frequency response function below about 900 Hz. Direct velocity feedback could therefore be implemented with a limited gain which gives reductions of about 15 dB in vibration level and about 8 dB in acoustic power level at the (1,1) mode of the smart panel. It has been also shown that the shaping error of PVDF actuator could limit the stability and performance of the control system.
Road Traffic Noise Status and Prediction
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 1015~1020
DOI : 10.5050/KSNVN.2004.14.10.1015
The road traffic noise becomes aggravated due to the rapid increase of vehicles. It has a great effect on the dwelling environment. Therefore we investigate the characteristics and sources of the road traffic noise through grasping the status of the road traffic noise. This paper is concerned with the description of the various factors affecting the generation and propagation of outdoor traffic noise. It is particularly concerned with the mathematical interpretation of these processes and the resulting development of prediction techniques which are now broadly used for both the environment impact assessment of road traffic noise and the planning and design of roads and adjoining land use.
Friction Snubber Development Using Sponge Iron
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 1021~1028
DOI : 10.5050/KSNVN.2004.14.10.1021
Developed friction snubbers changes the shock or vibration into a heat energy by mechanical friction. Snubber is divided into friction snubbers and hydraulic snubbers according to the operation types. However, hydraulic snubber has a lot of problems caused by temperature, humidity, radioactivity, and viscosity of hydraulic fluid. In these respects, to solve these problems, not only do friction snubber supplement lacks of hydraulic snubber but has also simpler structure than hydraulic snubber. In this paper, friction snubber used sponge iron by friction material is experimentally compared with general friction snubber In this results, the experiment verifies friction function and produce the manufacture condition for the effective friction snubber development.
Micro-scale Vibration Phenomena in a Linear Motion Guide Having Rolling Elements
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 1029~1034
DOI : 10.5050/KSNVN.2004.14.10.1029
Linear motion ( LM) guides having rolling elements have been used to position precision machines accurately. For ultra-accurate Positioning control of Precision machines, the understanding of the dynamic behavior of the LM guide at the macro and/or micro scales is most critical, but the research on this subject is rare. The objective of the present research is to investigate the vibration phenomena of the LM guide where balls are used as the rolling elements. Several experiments show the nonlinear characteristics of the LM guide such as hysteresis behavior and force-dependent natural frequencies phenomena.
Vibration Reduction of Electric Hand Grinder
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 1035~1040
DOI : 10.5050/KSNVN.2004.14.10.1035
The vibration of an electric hand grinder originates from the motor, gear, bearing, and fan. Its excessive vibration can be harmful to workers. To reduce the vibration of an electric hand grinder. frequency analysis for the vibration signals of a running electric hand grinder and modal test for the each part were done. The results show that the vibration is due to the resonance of the case. To remove the resonance, the case structure was modified and the bearing cap was replaced on a basis of the results of the rotor dynamic analysis using SAMCEF. As a result, the vibration of the electric hand grinder was reduced greatly.
Eigenvalue Branches and Flutter Modes of a Discontinuous Cantilevered Pipe Conveying Fluid
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 1041~1047
DOI : 10.5050/KSNVN.2004.14.10.1041
This paper deals with the dynamic stability and vibration of a discontinuous cantilevered Pipe conveying fluid. The present model consists of two segments with different cross-sections. Governing equations of motion are derived by extended Hamilton's principle, and the numerical scheme using finite element method is applied to obtain the discretized equations. The critical flow velocities and stability maps of the pipe are obtained by changing ratios of second area moment of inertia and mass ratios. Finally, the vibrational modes associated with flutter are shown graphically.
Acoustic Control of Optional Space Using Optimum Location of Absorbing Material
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 10, 2004, Pages 1048~1054
DOI : 10.5050/KSNVN.2004.14.10.1048
The Passive acoustic control is used in various fields, such as structures, automobiles, aircraft and so on. It is used in variety of acoustic field with the absorbing material, as one of the methods which can control the acoustic in optional space. In that case of passive control using this absorption material, it would be important to maximize the control performance of material property, numbers, geometry shape and the attached location of boundary area of the absorbing material. But realistically these variables, specially material Property, have no broad choice. Therefore, the position of absorbing material is the most important variable. In this study, we use the optimization method to minimize acoustic energy of optional space in the interest frequency attaching some absorbing materials to the boundary area. For analysis and optimization, this study uses the FEA and the conjugate gradient method. This optimization process is very efficient and useful in the passive acoustic control.