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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
Study on Acoustic Resonance of Air-conditioner Fan BLDC Motor
Lee, Hong-Joo ; Kwon, Joong-Hak ; Lee, Chang-Min ; Hwang, Gun-Yong ; Hwang, Sang-Moon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 863~869
DOI : 10.5050/KSNVN.2009.19.9.863
Acoustic noises generated during motor operation in mechanical system are from electromagnetic, mechanical, aerodynamic and electrical sources. For identification of mechanical noise origins, misalignment, unbalance, fan shape, resonance, and vibration modes have been extensively considered to describe noise behavior. An experiment-based approach as well as a mathematical approach needs to be adopted for a realistic study into noise and vibration of the motor, because motor noise characteristics differ from type to type due to various noise sources. This paper analyzes noise characteristics of a brushless DC motor for air-conditioner fan, and proves that the test motor noise originates from acoustic modes of airspace in the motor. The motor noise sensitivity analysis by design of experiments reveals that the noise characteristics are closely related to switching frequency and frame thickness.
Structural Vibration Analysis of a Helicopter Search Light Considering Aerodynamic Buffet Load
Kim, Yo-Han ; Kim, Dong-Man ; Kim, Dong-Hyun ; Choi, Hui-Ju ; Park, Yong-Suk ; Kim, Jong-Gun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 870~875
DOI : 10.5050/KSNVN.2009.19.9.870
In this study, computational structural vibration analysis of helicopter search light exposing unsteady buffet load have been conducted using combined advanced numerical methods. Unsteady CFD method based on Navier-Stokes equations is used to predict viscous buffet load due to flow separation effects. Full three-dimensional finite element model is constructed in order to conduct static and structural dynamic analyses of the search light model for two different typical flight speeds. Also, the correct performance of the search light can be physically estimated to examine the actual lighting area considering the effects of structural deformations.
Sound Radiation Characteristics of Rectangular Plates with a Guided Edge Condition
Yoo, Ji-Woo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 876~883
DOI : 10.5050/KSNVN.2009.19.9.876
The radiation of sound from a rectangular plate with a guided edge condition is investigated. By taking this particular boundary condition into account, simple analytical forms of the average radiation efficiency and radiation power based on the modal approach can be found, where the cross-modal terms can average out for all possible point excitation locations. Design variables of the plate such as thickness, aspect ratio, and damping that are closely related to the sound radiation are mainly discussed. The radiation power of the guided plate is found to be governed by the piston mode as well as the critical frequency. While both the radiation efficiency and the radiation power seem to be influenced by thickness and a large aspect ratio, damping loss factor seems less important to the radiation power. It is also shown that no clear corner and edge mode regions may be found for the guided case, unlike the pinned.
Structural Damage Detection Using Swarm Intelligence and Model Updating Technique
Choi, Jong-Hun ; Koh, Bong-Hwan ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 884~891
DOI : 10.5050/KSNVN.2009.19.9.884
This study investigates some of swarm intelligence algorithms to tackle a traditional damage detection problem having stiffness degradation or damage in mechanical structures. Particle swarm(PSO) and ant colony optimization(ACO) methods have been exploited for localizing and estimating the location and extent damages in a structure. Both PSO and ACO are population-based, stochastic algorithms that have been developed from the underlying concept of swarm intelligence and search heuristic. A finite element (FE) model updating is implemented to minimize the difference in a set of natural frequencies between measured and baseline vibration data. Stiffness loss of certain elements is considered to simulate structural damages in the FE model. It is numerically shown that PSO and ACO algorithms successfully completed the optimization process of model updating in locating unknown damages in a truss structure.
A Study on Vibration Reduction of an Industrial Chop Saw in Operation
Kim, Doo-Hwan ; Im, Hyung-Bin ; Chung, Jin-Tai ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 892~898
DOI : 10.5050/KSNVN.2009.19.9.892
In this paper, a cause of a shock of an industrial chop saw is identified by experimental method and the shock is reduced by structural modifications. For the shock identification, vibration signals are measured by an accelerometer when the chop saw operates. Through some experiments, it is found that the shock is occurred by a slip between a spindle and a wheelwasher of the chop saw. To reduce the shock, One method is to lower the mass moment of inertia of the wheelwasher and the angular rotating acceleration of it. Another method is to broaden a contact area between the wheelwasher and the spindle. After designing and analyzing the wheelwasher and the spindle mechanically, a prototype of them is built. With the manufactured prototype, the performances and design requirements of them are experimentally verified by the response measurements.
Modal Characteristics and Vibration Control of Cylindrical Shell Structure : Experimental Results Comparison in the Air and Water
Sohn, Jung-Woo ; Kwon, Oh-Cheol ; Choi, Seung-Bok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 899~906
DOI : 10.5050/KSNVN.2009.19.9.899
In the present paper, dynamic characteristics and vibration control performance of a cylindrical shell structure are experimentally investigated and results are presented in the air and underwater conditions. End-capped cylindrical shell structure is manufactured and macro-fiber composite(MFC) actuators are attached on the inside-surface of the structure. Modal characteristics are studied in the air and under the water conditions and then equation of motion of the structure is derived from the test results. Structural vibration control performances of the proposed structure are evaluated via experiments with optimal control algorithm. Vibration control performances are presented both in the frequency and time domains.
Study on 3D Sound Source Visualization Using Frequency Domain Beamforming Method
Hwang, Eun-Sue ; Lee, Jae-Hyung ; Rhee, Wook ; Choi, Jong-Soo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 907~914
DOI : 10.5050/KSNVN.2009.19.9.907
An approach to 3D visualization of multiple sound sources has been developed with the application of a moving array technique. Frequency domain beamforming algorithm is used to generate a beam power map and the sound source is modeled as a point source. When a conventional delay and sum beamformer is used, it is considered that 2D distribution of sensors leads to have deficiency in spatial resolution along a measurement distance. The goal of moving an array in this study is to form 3D array aperture surrounding multiple sound sources so that the improved spatial resolution in a virtual space can be expected. Numerical simulation was made to examine source localization capabilities of various shapes of array. The 3D beam power maps of hemispherical and spherical distribution are found to have very sharp resolution. For experiments, several sound sources were placed in the middle of defined virtual space and arc-shaped line array was rotated around the sources. It is observed that spherical array shows the most accurate determination of multiple sources` positions.
Strain Sensor Application Using Cellulose Electro-Active Paper(EAPap)
Jang, Sang-Dong ; Kim, Joo-Hyung ; Kim, Jae-Hwan ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 915~921
DOI : 10.5050/KSNVN.2009.19.9.915
Cellulose based electro-active paper(EAPap) is considered as a new smart material which has a potential to be used for biomimetic actuators and sensors. Beside of the natural abundance, cellulose EAPap is fascinating with its biodegradability, lightweight, high mechanical strength and low actuation voltage. When the external stress is applied to EAPap, it can generate the electrical output due to its piezoelectric property. Using piezoelectric behavior of EAPap, we studied the feasibility of EAPap as mechanical strain sensor applications and compared to commercial strain sensor. By measuring the induced output voltage from the thin piezoelectric cellulose EAPap under static and dynamic force, we propose cellulose EAPap film as a potential strain sensor material.
Acoustic Characteristics Analysis of Cylindrical Array for the Directional and Omni-directional mode Using the Boundary Element Method
Lee, Jung-Min ; Seo, Hee-Seon ; Cho, Yo-Han ; Baek, Kwang-Ryul ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 922~927
DOI : 10.5050/KSNVN.2009.19.9.922
The transducers used in active sonar on surface ships are packed in a specific geometry in the array drum in order to meet the requirements such as the source level, directional beam pattern, etc. This paper describes the acoustic characteristics of the cylindrical array which is based on a 64 vertical staves arrangement, each stave composed 5 independent transducers. Firstly, the single transducer on the rigid baffle in the water is analyzed with the Finite Element Method. From the result of the FE analysis nodal velocities on the radiation surface is calculated and used with the boundary conditions of the transducers mounted on the array drum. Then the acoustic pressure is calculated in the field points using the Boundary Element Method and the other acoustic informations, the source level, beam pattern, near field and far-field distance, were acquired.
Characteristics of Impulsive Noise of Waterfront Construction Site and Its Effects on Fishes
Bae, Jong-Woo ; Park, Ji-Hyun ; Yoon, Jong-Rak ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 928~934
DOI : 10.5050/KSNVN.2009.19.9.928
Underwater impulsive sound such as underwater blasting noise, piling noise and stone breaking hammer affects marine animal hearing response and organs. This study describes the characteristics of various impulsive noise from waterfront construction site and their effect on fish. Time constant, peak pressure, energy and SEL(sound exposure level) of four different underwater impulsive sounds are quantified. Auditory and non-auditory tissue damage ranges are derived by comparing their quantities to the exposure criteria for fish. Damage ranges of auditory tissue and non-auditory tissue of underwater boring blast of 150 kg of charge, are about 100 m and 300 m, respectively. Other three impulsive sounds also gives damage effects but less than that of underwater boring blast.
Study on Detection of Crack and Damage for Cantilever Beams Using Vibration Characteristics
Son, In-Soo ; Ahn, Sung-Jin ; Yoon, Han-Ik ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 935~942
DOI : 10.5050/KSNVN.2009.19.9.935
In this paper, the purpose is to investigate the natural frequency of a cracked Timoshenko cantilever beams by FEM(finite element method) and experiment. In addition, a method for detection of crack in a cantilever beams is presented based on natural frequency measurements. The governing differential equations of a Timoshenko beam are derived via Hamilton`s principle. The two coupled governing differential equations are reduced to one fourth order ordinary differential equation in terms of the flexural displacement. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. The detection method of a crack location in a beam based on the frequency measurements is extended here to Timoshenko beams, taking the effects of both the shear deformation and the rotational inertia into account. The differences between the actual and predicted crack positions and sizes are less than 6 % and 23 % respectively.
Measuring Structural Vibration from Video Signal Using Curve Fitting
Jeon, Hyeong-Seop ; Choi, Young-Chul ; Park, Jong-Won ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 943~949
DOI : 10.5050/KSNVN.2009.19.9.943
Many studies for measuring vibration using image signal are suggested. These methods can measure vibration of multi-points simultaneously. However, it has the disadvantage that is very sensitive to an environment. If the measured environment is not good, image signals can be measured including much background noise. So, it is difficult to obtain accurate vibration from the measured image signals. Another problem is that camera imaging has a resolution limit. Because the resolution of the camera image is relatively much lower than that of a data acquisition system, accurate measuring vibration cannot be performed. In this paper, we proposed the enhanced technique for measuring vibration using camera signal. The key word of this paper is a curve fitting. The curve fitting can exactly detect the measurement line of interested object. So, we can measure the vibration in noisy environment. Also, it can overcome the resolution limit.
Sloshing Reduction Characteristics to Baffle for Cylindrical Liquefied Fuel Tank subject to Dynamic Load
Koo, Jun-Hyo ; Cho, Jin-Rae ; Jeong, Weui-Bong ; Kim, Dang-Ju ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 950~959
DOI : 10.5050/KSNVN.2009.19.9.950
Liquid fluctuation called sloshing within liquid-storage tank gives rise to the significant effect on the dynamic stability of tank. This liquid sloshing can be effectively suppressed by installing baffles within the tank, and the suppression effect depends strongly on the design parameters of baffle like the baffle configuration. The present study is concerned with the parametric evaluation of the sloshing suppression effect for the CNG-storage tank, a next generation liquefied fuel for vehicles, to the major design parameters of baffle, such as the baffle configuration, the installation angle and height, the hole size of baffle. The coupled FEM-FVM analysis was employed to effectively reflect the interaction between the interior liquid flow and the tank elastic deformation.
Effect of Type and S/N Ratio of Combined Noise Sources on Sleep Disturbance
Lee, Pyoung-Jik ; Shim, Myoung-Hee ; Jeon, Jin-Yong ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 960~966
DOI : 10.5050/KSNVN.2009.19.9.960
The World Health Organization(WHO) has reported the sleep disturbance as one of the adverse effects of noise. And the effect of combined noise sources on human have been investigated because community noises are seldom heard and are concurrent. Therefore, the effects of combined noise source and its S/N ratio on sleep disturbance were investigated; as a single noise source, road traffic noise was selected, and construction and movie noise were combined with road traffic noise. Tests for sleep disturbance were conducted in bedrooms and the effect on each subjects` sleep was evaluated by questionnaire. The results showed that the rate of awakening increased slightly only when the SPL of construction noise was 10 dB higher than that of road traffic noise. It was also found that the sleep disturbance was affected by the type of combined noise sources and its S/N ratio.
The Transmissibility of the Compact Disc Player due to Temperature
Lee, Tae-Keun ; Kim, Byoung-Sam ; Chi, Chang-Heon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 9, 2009, Pages 967~972
DOI : 10.5050/KSNVN.2009.19.9.967
To investigate the vibration characteristics of compact disc player(CDP) due to excited vibration and disturbances, it is necessary to consider the transmissibility of the CDP. The disturbances as well as the temperature in the vehicle are the one of the important factors when CDP is designed. In this study, the effect on the temperature of the oil damper, which is applied to anti-vibration system of the CDP, was investigated. When the temperature was changed from
and the properties of the oil damper (hardness of rubber, viscosity of oil) were changed, the transmissibility was measured. When the damper rubber has the large hardness, the difference of the transmissibility and natural frequency due to temperature showed the remarkable change as compared with the those of damper viscosity.