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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
Journal Basic Information
Journal DOI :
The Korean Society for Noise and Vibration Engineering
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Volume & Issues
Volume 17, Issue 12 - Dec 2007
Volume 17, Issue 11 - Nov 2007
Volume 17, Issue 10 - Oct 2007
Volume 17, Issue 9 - Sep 2007
Volume 17, Issue 8 - Aug 2007
Volume 17, Issue 7 - Jul 2007
Volume 17, Issue 6 - Jun 2007
Volume 17, Issue 5 - May 2007
Volume 17, Issue 4 - Apr 2007
Volume 17, Issue 3 - Mar 2007
Volume 17, Issue 2 - Feb 2007
Volume 17, Issue 1 - Jan 2007
Selecting the target year
Prediction and Measurement of Sound Transmission Loss for Multi-layered Acoustical Materials
Park, So-Hee ; Park, Chul-Min ; Chae, Ki-Sang ; Kang, Yeon-June ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1013~1020
DOI : 10.5050/KSNVN.2007.17.11.1013
In this paper, the predictions and measurements of sound transmission loss(STL) are discussed for various types of acoustical materials and carpets. Random incidence sound transmission losses are measured by the sound intensity method. The in-house software HONUS2005 is used to predict TL and estimate the various physical properties such as the flow resistivity, the structure factor, the porosity, the Possion`s ratio, and etc. After this estimation, various multi-layered materials with a steel plate are measured and predicted. In particular, Carpets are assumed to be membranes to predict acoustical performance. To confirm this assumption, double and triple-layered cases are also observed including two different kinds of carpets.
Development of Noise Prediction Program in Construction Sites
Kim, Ha-Geun ; Joo, Si-Woong ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1021~1027
DOI : 10.5050/KSNVN.2007.17.11.1021
A construction noise is the main reason for people`s petition among the pollution. The purpose of this study is to develop the noise prediction program to see the level of the noise on the construction site more accurately. For this purpose, the database of the power level on the various equipments was made. The noise reduction by distance and the noise reduction by diffraction of barrier were mainly considered and calculated. The simple noise prediction program will provide the information about proper height and length of the potable barrier which satisfies noise criteria of the construction sites from a construction planning stage. To investigate the reliability of this program, the predicted data was compared with the measured data. An average of difference between measured data and predicted data is
and a coefficient of correlation is about
Measurement and Monitoring of Mechanical Loads of Wind Turbines Using Distributed Fiber Optic Sensor
Lee, Jong-Won ; Huh, Young-Cheol ; Nam, Yong-Yun ; Lee, Geun-Ho ; Kim, Yoo-Sung ; Lee, Yong-Bae ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1028~1036
DOI : 10.5050/KSNVN.2007.17.11.1028
A method for measurement and monitoring of mechanical loads in large slender structures such as wind turbine blade and tower is presented based on continuous strain data obtained from distributed fiber optic sensor. An experimental study was carried out on an aluminum cantilever beam. A static load test was performed and the calculated moment from the distributed fiber optic sensor agree well with the actual applied moment. A series of damages was inflicted on the beam, and vibration tests were carried out for each damage case. The estimated natural frequencies from the distributed fiber optic sensor for each damage case are found to compare well with those from a conventional accelerometer and a numerical analysis based on an energy method.
Analysis of Interior Noise of KTX in Tunnel with Concreted Track
Kim, Jae-Chul ; Lee, Chan-Woo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1037~1042
DOI : 10.5050/KSNVN.2007.17.11.1037
KTX trains show a high interior noise level in tunnel with concreted track at 300 km/h. Generally, the concreted track has higher sound emissions compared with ballasted track due to the reduced absorption and the major sources of interior noise for KTX are known as the aerodynamic noise and rolling noise. Therefore, It is necessary to find out noise source and noise components to affect interior noise in tunnel with concreted track. In this study, we measure the noise and vibration inside KTX in tunnel in order to find the cause of the interior noise of KTX. The analysis results show that the interior noise of KTX in tunnel with concreted track is increased sharply by a low frequency below 80 Hz. We know that the low frequency noise inside KTX in tunnel with concreted track is generated at the natural frequency of carbody by aerodynamic noise outside gangway and rolling noise. In order to reduce the noise level at 80 Hz, modification of mud-flap length between carbodys is suggested and the effect of noise reduction is examined in tunnel with concreted track.
Design of Moving Magnet Type Optical Pickup Actuator with High Frequencies of the Flexible Modes
Song, Myeong-Gyu ; Kim, Yoon-Ki ; Park, Young-Pil ; Yoo, Jeong-Hoon ; Park, No-Cheol ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1043~1049
DOI : 10.5050/KSNVN.2007.17.11.1043
Data transfer rate and storage capacity are main criteria of the performance of the optical disk drive. The highest data transfer rate and the largest storage capacity is most desirable. To increase these performances, the actuator of the optical disk drive should have a high servo bandwidth to compensate the vibration of an optical disk. The servo bandwidth is limited by some flexible modes of the actuator, thus it is essential to increase the natural frequencies of the flexible modes. In this paper, we suggested a moving magnet type actuator having high frequencies of the flexible modes. Generally, the moving magnet type actuator has an advantage to increase the natural frequencies of the flexible modes because the moving magnet type actuator has simple structure and the Young`s modulus of magnet is high. However, large moving mass and inefficiency of EM(electromagnetic) circuit cut down driving sensitivities of the actuator. To improve driving sensitivities, we designed the model with the closed electromagnetic circuit for tracking direction. In addition, driving sensitivities and the natural frequencies of the flexible modes were improved by using DOE(design of experiments) for electromagnetic circuit and modifying the lens holder.
An Experimental Study on the Optimistic Recognition Level of Public Address System as a Soundscape Application Facility
Song, Min-Jeong ; Jang, Gil-Soo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1050~1055
DOI : 10.5050/KSNVN.2007.17.11.1050
P.A.(public address) system is considered as an useful active soundscape appliance which can gives a place identity and vitality by introducing conventional musics, environmental musics, bird singing sounds etc. In this study, the main aim is to know the optimistic distance from the speaker and sound pressure level range of introducing sound. So, the sound pressure level of P.A. system due to distances were measured and subjects` responses with level variations were checked. The main results are as follows. Level range from 64 dB to 71 dB is comfortable for subjects. And the optimal level of introducing sound is related with sound source characteristics. The results of this study could be used for street furniture location design and P.A. system output level.
The Analysis of Noise Contribution about Drum Washer under Dehydrating Condition Using Multi-dimensional Spectral Analysis
Kim, Ho-San ; Park, Sang-Gil ; Kang, Kwi-Hyun ; Lee, Jung-Yoon ; Oh, Jae-Eung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1056~1063
DOI : 10.5050/KSNVN.2007.17.11.1056
Recently, there has been a growing consumer interest in the amount of noise produced by household electrical appliances. The designer of the product must identify the source of the noise, in order to reduce the noise. In the case of a household electric appliance such as the washing machine, there is consumer`s complaint about the noise that is generated during the dehydrating condition. Because of several noise sources combined each other. It is difficult to identify the noise sources that contribute to the noise output. Multi-Dimensional Spectral Analysis (MDSA) is a method that can remove the correlation between different noise sources, and it expresses the key contributing factor as a unique output. This study utilized MDSA to analyze the contribution of each input in the noise output during the dehydrating condition.
A Study on the Noise Assessment of Specific Vehicles at Metropolitan Landfill Area Using Noise Map
Park, In-Sun ; Park, Sang-Kyu ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1064~1068
DOI : 10.5050/KSNVN.2007.17.11.1064
Around metropolitan landfill area, specific vehicles such as garbage carrying trucks make noise problems and residents near landfill area organized to protest. However, it is difficult to distinguish the effect of noise of specific vehicles (ex: garbage trucks). In this study, noise map and CRTN were used to assess the noise from specific vehicles. Noise levels, which were predicted by using measured parameters such as traffic flow, traffic speed, composition of traffic for 1 year, were compared with measured results of noise level.
Dynamic Analysis of a Linear Feeder for Uniform Transformation of Grains
Lee, Kyu-Ho ; Kim, Syung-Hyun ; Chung, Jin-Tai ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1069~1076
DOI : 10.5050/KSNVN.2007.17.11.1069
The purpose of this study is to improve the performance of a linear feeder that can transport grains uniformly. In order to analyze the dynamic behaviors of a linear feeder, the displacements of the feeder are measured by several accelerometers when it is in an operating condition. After the signal data from the accelerometers are captured in the time domain, the feeder motion in the space is visualized by using graphic computer software. In addition, a dynamic model of the feeder is established for a multi-body dynamics simulation. For the dynamic simulation, RecurDyn, which is a commercial multi-body dynamic package, is used. From the experimental and the computational approaches, an optimal dynamic motion is obtained for uniform transportation of grains. Furthermore, we also consider the determination of design parameters for optimal dynamic motion such as centroid, stiffness, and damping coefficient of the feeder system.
An Analytical Study on the Magnetic Levitation System Using a Halbach Magnet Array
Moon, Seok-Jun ; Yun, Dong-Won ; Cho, Hung-Je ; Park, Sung-Whan ; Kim, Byung-Hyun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1077~1085
DOI : 10.5050/KSNVN.2007.17.11.1077
Typically, three types of levitation technologies are applied to magnetic levitation systems: electromagnetic suspension, electrodynamic suspension, and hybrid electromagnetic suspension. A Halbach array is a special arrangement of permanent magnets which augments the magnetic field on one side of the device while cancelling the field to near zero on the other side. The application of this Halbach array magnet to the electrodynamic suspension has been recently studied in order to increase the levitation capability. This paper is focused on an analytical method of the magnetic levitation system using Halbach array magnet. The suitability of the proposed method is verified with comparing to the finite element method. In addition, dynamic stability of the magnetic levitation system is discussed. From this study, it is confirmed that the proposed method provides a reasonable solution with less computation time compared to the finite element method and the magnetic levitation system using Halbach array magnet is stable dynamically.
Free Vibration Analysis of Rectangular Plate with Multiple Circular Cutouts by Independent Coordinate Coupling Method
Kwak, Moon K. ; Song, Myung-Ho ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1086~1092
DOI : 10.5050/KSNVN.2007.17.11.1086
This paper is concerned with the vibration analysis of a rectangular plate with multiple circular holes. On the contrary to the case of rectangular plate with multiple rectangular holes, it is very difficult to perform qualitative analysis on natural vibration characteristics because of geometrical inconsistency. In this paper, we applied the Independent Coordinate Coupling Method(ICCM) to the addressed problem, which was developed to compute natural vibration characteristics of the rectangular plate with a circular hole and proven to be computationally effective. The ICCM is based on Rayleigh-Ritz method but utilizes independent coordinates for each hole domain. By matching the deflection conditions for each hole imposed on the expressions, we can easily derive the reduced mass and stiffness matrices. The resulting equation is then used for the calculation of the eigenvalue problem. The numerical results show the efficacy of the Independent Coordinate Coupling Method.
A Study on the Dynamic Characteristics of Door Module for Vehicle
Bae, Chul-Yong ; Kim, Chan-Jung ; Kwon, Seong-Jin ; Lee, Bong-Hyun ; Jang, Woon-Sung ; Lee, Joon-Woo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1093~1101
DOI : 10.5050/KSNVN.2007.17.11.1093
This study presents the design improvement process for door module. Its objective evades the resonance generated at module plate due to the operation of window regulator motor. For this study, the design improvement process is composed of experimental methods having three steps. First step is modal analysis at door assembly status for acquisition of dynamic characteristics which are modal frequency and damping. Second step is a vibration experiment to get the test mode considered an efficiency of window regulator motor. Last step is a vibration measurement by the form of
array on module plate. A vibration measurement of
array form can be got to three analysis results which are a transfer path of vibration using cross correlation function, a vibration map using OA level and a contribution by frequency band using coherent output power spectrum on module plate. These results are applied to SDM(structural dynamic modification) for design improvement to get around the resonance on module plate by the excitation of window regulator motor.
Fault Tolerant Control of Homopolar Magnetic Bearings Using Flux Isolation
Na, Uhn-Joo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1102~1111
DOI : 10.5050/KSNVN.2007.17.11.1102
The theory for a fault-tolerant control of homopolar magnetic bearings is developed. New coil winding law is utilized such that control fluxes are isolated for an 8-pole homopolar magnetic bearing. Decoupling chokes are not required for the fault tolerant magnetic bearing since C-core fluxes are isolated. If some of the coils or power amplifiers suddenly fail, the remaining coil currents change via a distribution matrix such that the same magnetic forces are maintained before and after failure. Lagrange multiplier optimization with equality constraints is utilized to calculate the optimal distribution matrix that maximizes the load capacity of the failed bearing. Some numerical examples of distribution matrices are provided to illustrate the theory. Simulations show that very much the same dynamic responses (orbits or displacements) are maintained throughout failure events while currents and fluxes change significantly.
Thiele Small Parameters Estimation for Pseudo Loudspeaker within 10 mm Grade Circular-type Microspeaker
Park, Seok-Tae ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1112~1118
DOI : 10.5050/KSNVN.2007.17.11.1112
It was discussed to identify Thiele Small Parameters for Pseudo loudspeaker within 10mm grade microspeaker attached to closed-box using known dynamic mass of moving parts. Also, enhanced circuit model for vented-box micro speaker system was used to more accurately simulate electrical impedance curves for real vented-box microspeaker system and compared to test results. Consequently, it showed that micro speaker could be modeled by pseudo loudspeaker TS parameters similar to general loudspeaker. Vented-box microspeaker model with pseudo loudspeaker TS parameters was well suited to describe real microspeaker. Also, it was proposed to estimate volume of rear closed-box of microspeaker without design specifications.
Effects of Crack on Stability of Cantilever Pipe Conveying Fluid
Son, In-Soo ; Yoon, Han-Ik ; Kim, Dong-Jin ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1119~1126
DOI : 10.5050/KSNVN.2007.17.11.1119
In this paper, the dynamic stability of a cracked cantilever pipe conveying fluid with tip mass is investigated. The pipe is modelled by the Euler-Bernoulli beam theory in which rotatory inertia and shear deformation effects are ignored. The equation of motion is derived by the energy expressions using extended Hamilton`s Principle. The crack section is represented by a local flexibility matrix connecting two undamaged pipe segments. The influence of the crack severity, the position of crack, the mass ratio, and a tip mass on the stability of a cantilever pipe conveying fluid are studied by the numerical method. Besides, the critical flow velocity and the stability maps of the pipe system as a function of mass ratios(
) for the changing each parameter are obtained.
Correlation between the Linear Impulse and Ball Spin Rate
Roh, Woo-Jin ; Lee, Chong-Won ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 11, 2007, Pages 1127~1132
DOI : 10.5050/KSNVN.2007.17.11.1127
Golf ball spin rate after impact with club is created by the contact force, which is greatly influenced by ball and club mass, material, impact speed, and club loft angle. Previous studies showed that the contact force is determined as the resultant force of the reaction forces normal and tangential to the club face at the contact point. The normal force causes the compression and restitution of the ball, and the tangential force creates the spin. Especially, the tangential force takes either positive or negative values as the ball rolls and slides along the club face during impact. Although the positive and negative tangential forces are known to create and reduce the back spin rate, respectively, the mechanism of ball spin creation has not yet been discussed in detail. It is shown in this work that the linear impulse of the tangential force is directly related to generation of back spin rate of golf ball. The linear impulse can be calculated from the tangential force, which depends upon many factors such as ball and club mass, material, impact speed, and club loft angle. In this research, the influence of the contact force between golf club and ball is investigated to analyze the mechanism of impact. For this purpose, the contact force and the contact time at impact between golf club head and ball are computed using FEM.