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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 22, Issue 12 - Dec 2012
Volume 22, Issue 11 - Nov 2012
Volume 22, Issue 10 - Oct 2012
Volume 22, Issue 9 - Sep 2012
Volume 22, Issue 8 - Aug 2012
Volume 22, Issue 7 - Jul 2012
Volume 22, Issue 6 - Jun 2012
Volume 22, Issue 5 - May 2012
Volume 22, Issue 4 - Apr 2012
Volume 22, Issue 3 - Mar 2012
Volume 22, Issue 2 - Feb 2012
Volume 22, Issue 1 - Jan 2012
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Investigating Natural Frequency Analysis and Measurement of Railway Vehicle to Avoid Resonance
Hong, Do-Kwan ; Jeong, Jae-Boo ; Jung, Seung-Wook ; Kim, Gyeong-Bae ; Ahn, Chan-Woo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 713~719
DOI : 10.5050/KSNVE.2012.22.8.713
This paper deals with the natural frequency analysis and two experiments to evaluate first twisting and bending natural frequency of railway vehicle. The KS R 9228 testing method is generally performed as pseudo FRF(frequency response function) which is widely used by two accelerometers. The exciting method is utilized using the load weight(1 ton release). The modal testing is used to verify KS R 9228 testing result and the natural frequency analysis result. The first twisting and bending natural frequency should be above 10 Hz by resonance which is mostly generated between bogie and vehicle frame exciting low frequency. The first twisting and bending natural frequency of railway vehicle are successfully verified between analysis and test.
Road Noise Prediction Based on Frequency Response Function of Tire Utilizing Cleat Excitation Method
Park, Jong-Ho ; Hwang, Sung-Wook ; Lee, Sang-Kwon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 720~728
DOI : 10.5050/KSNVE.2012.22.8.720
It is important for identification of noise and vibration problem of tire to consider influence of interaction between road and tire. A quantification of road noise is a challenging issue in vehicle NVH due to extremely complicated transfer paths of road noise as well as the difficulty in an experimental identification of input force from tire-road interaction. A noise caused by tire is divided into road noise(structure-borne noise) and pattern noise(air-borne noise). Pattern noise is caused by pattern shape of tire, which has larger than 500 Hz, but road noise is generated by the interactions between a tire and a vehicle body. In this paper, we define the quantitative analysis for road noise caused by interactions between tire and road parameters. For the identification of road noise, the chassis dynamometer that is equipped
square cleat in the semi-anechoic chamber is used, and the tire spindle forces are measured by load cell. The vibro-acoustic transfer function between ear position and wheel center was measured by the vibro-acoustic reciprocity method. In this study three tires with different type of mechanical are used for the experiment work.
LQG/LTR Control of Hydraulic Positioning System with Dead-zone
Kim, In-Soo ; Kim, Yeung-Shik ; Kim, Ki-Bum ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 729~735
DOI : 10.5050/KSNVE.2012.22.8.729
A LQG/LTR(linear quadratic Gaussian/loop transfer recovery) controller with an integrator is designed to control the electro-hydraulic positioning system. Without considering the nonlinearity in the dead-zone, computer simulations are performed and show good performances and tracking abilities with the feedback controller based on the linear system model. However, the performance of the closed loop hydraulic positioning system shows big steady-state error in real system because of the dead-zone. In this paper, the feedback controller with a nonlinear compensator is introduced to overcome the dead-zone phenomenon in hydraulic systems. The inverse dead-zone as a nonlinear compensator is used to cancel out the dead-zone phenomenon. Experimental tests are performed to verify the performance of the controller.
A Basic Experimental Study on the Squeak Noise Using the Pin-on-disk
Nam, Jae-Hyun ; Kang, Jae-Young ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 736~741
DOI : 10.5050/KSNVE.2012.22.8.736
Squeak noise is studied by using the pin-on-disk system with aluminum pin and steel disk. Noise induced by friction is measured with respect to the normal loads and sliding speeds. The negative slope of friction-velocity curve is seen when the squeak noise occurs. It is found that the normal load influences on the sound level of squeak noise. From the hammering test, the major frequency of the squeak noise is shown to correspond to one of system modes, which implies that squeak phenomenon arises from the unstable system modes. The result of FE analysis shows that the major squeak mode is the bending mode of the pin.
Development of a Modified NDIF Method for Extracting Highly Accurate Eigenvalues of Arbitrarily Shaped Acoustic Cavities
Kang, S.W. ; Yon, J.I. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 742~747
DOI : 10.5050/KSNVE.2012.22.8.742
A modified NDIF method using a sub-domain approach is introduced to extract highly accurate eigenvalues of two-dimensional, arbitrarily shaped acoustic cavities. The NDIF method, which was developed by the authors for the eigen-mode analysis of arbitrarily shaped acoustic cavities, has the feature that it yields highly accurate eigenvalues compared with other analytical methods or numerical methods(FEM and BEM). However, the NDIF method has the weak point that it can be applicable for only convex cavities. It was revealed that the solution of the NDIF method is very inaccurate or is not suitable for concave cavities. To overcome the weak point, the paper proposes the sub-domain method of dividing a concave domain into several convex domains. Finally, the validity of the proposed method is verified in two case studies, which indicate that eigenvalues obtained by the proposed method are more accurate compared to the exact method, the NDIF method, or FEM(ANSYS).
A Dry Friction Model to Realize Stick for Simulation of the System with Friction and Accuracy Verification of the Friction Model
Choi, Chan-Kyu ; Yoo, Hong-Hee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 748~755
DOI : 10.5050/KSNVE.2012.22.8.748
Friction causes self-excited vibration, stick-slip vibration and any other friction-induced phenomena. That kinds of vibrations cause chatter and squeal. In order to predict such vibrations accurately, employing an accurate friction model is very important because a dynamic behavior of a system with friction is dominantly governed by a friction model. A Coulomb friction model is the most widely known model. Coulomb friction model is useful model to obtain analytical solutions of the system with friction and the model gives relatively good simulation result. However, defining a friction force at a stick state in simulation is hard because of the characteristic itself and a Coulomb friction model is discontinuous function between a static and a dynamic friction coefficient. Therefore, applying the Coulomb friction model to a simulation is not appropriate. In order to resolve these problems, an approximated Coulomb friction model was developed using simple and continuous function. However, an approximated Coulomb friction model cannot realize stick. Therefore, an approximated Coulomb friction model cannot describe friction phenomena accurately. In order to analyze a friction phenomenon accurately, a friction model for a simulation was proposed in this paper. A proposed friction model realizes stick and gives reasonably good results compared to results obtained by the simulation employing an approximated Coulomb friction model. Accuracy of a proposed friction model was verified by comparing experimental results.
Low-frequency Noise Reduction in an Enclosure by using a Helmholtz Resonator Array
Park, Soon-Hong ; Seo, Sang-Hyun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 756~762
DOI : 10.5050/KSNVE.2012.22.8.756
A method of the low-frequency noise reduction in an enclosure by using an array of Helmholtz resonator is presented. An integral form of equation, which represents the acoustical coupling between the internal sound field and the resonator array, is formulated so that the boundary element method can be applied to solve the coupling problem. It is shown that the resonator array on the surface of the enclosure can be regarded as impedance patches on the boundary element. Experiments on a simple enclosure acoustically coupled with an array of resonators are conducted to verify the method. The predicted noise reduction by the boundary element method shows good agreement with the measured one. The effects of the resistance of resonators as well as the number of resonators on the noise reduction are demonstrated. As a practical example, the presented method is applied to the payload fairing of a space launcher with resonator arrays. It is demonstrated that the resistance of resonators affects significantly the required number of resonators to achieve a desired noise reduction.
Free Vibrations of Fluid-filled Cylindrical Shells on Partial Elastic Foundations
Jung, Kang ; Kim, Young-Wann ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 763~770
DOI : 10.5050/KSNVE.2012.22.8.763
The free vibration characteristics of fluid-filled cylindrical shells on partial elastic foundations are investigated by an analytical method. The cylindrical shell is fully or partially surrounded by the elastic foundations, these are represented by the Winkler or Pasternak model. The motion of shell is represented by the first order shear deformation theory to account for rotary inertia and transverse shear strains. The steady flow of fluid is described by the classical potential flow theory. The fluid-structure interaction is considered in the analysis. The effect of internal fluid can be considered by imposing a relation between the fluid pressure and the radial displacement of the structure at the interface. To validate the present method, the numerical example is presented and compared with the available existing results.
Identification of the Shear Velocities of Near Surface Soils Using Torsional Guided Waves
Park, Kyung-Jo ; Oh, Hyung-Soo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 771~776
DOI : 10.5050/KSNVE.2012.22.8.771
A technique is presented that uses a circular waveguide for the measurement of the bulk shear(S-wave) velocities of unconsolidated, saturated media, with particular application to near surface soils. The technique requires the measurement of the attenuation characteristics of the fumdamental T(0,1) mode that propagates along an embedded pipe, from which the acoustic properties of the surrounding medium are inferred. From the dispersion curve analysis, the feasibility of using T(0,1) mode which is non-dispersive and have constant attenuation over all frequency range is discussed. The principles behind the technique are discussed and the results of an experimental laboratory validation are presented. The experimental data are best fitted for the different depths of wetted sand and the shear velocities as a function of depths are formulated using power law curves.
Improved Vibration Vector Intensity Field for FEM and Experimental Vibrating Plate Using Streamlines Visualization
Fawazi, Noor ; Jeong, Jae-Eun ; Oh, Jae-Eung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 777~783
DOI : 10.5050/KSNVE.2012.22.8.777
Vibration intensity has been used to identify the location of a vibration source in a vibrating system. By using vectors representation, the source of the power flow and the vibration energy transmission paths can be revealed. However, due to the large surface area of a plate-like structure, clear transmission paths cannot be achieved using the vectors representation. Experimentally, for a large surface object, the number of measured points will also be increased. This requires a lot of time for measurement. In this study, streamlines representation is used to clearly indicate the power flow transmission paths at all surface plate for FEM and experiment. To clearly improve the vibration intensity transmission paths, streamlines representation from experimental works and FEM computations are compared. Improved transmission paths visualization for both FEM and experiment are shown in comparison to conventional vectors representation. These streamlines visualization is useful to clearly identify vibration source and detail energy transmission paths especially for large surface plate-like structures. Not only that, this visualization does not need many measured point either for experiment or FEM analysis.
Hub Parametric Investigation of Main Rotor Stability of Bearingless Helicopter
Yun, Chul-Yong ; Kee, Young-Jung ; Kim, Tae-Joo ; Kim, Deog-Kwan ; Kim, Seung-Ho ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 784~790
DOI : 10.5050/KSNVE.2012.22.8.784
This paper describes a stability and dynamic characteristics of bearingless helicopter main rotor in hover. Baseline rotor configuration is defined and modal analysis for the configuration is taken to verify the dynamic characteristics. The kinematic pitch-lag couplings through ways of pitch link installation are analyzed to know effects on loads, frequencies and stability. The effects of pitch link attachments in spanwise direction and chordwise direction as well as pitch link inclination on thrust, power, flpa-lag-pitch mode frequencies and inplane damping are examined. Pitch link at trailing edge location in chordwise direction has influence on aeroelastic stability of the rotor. Also, the pitch link with negative inclination angle makes inplane damping increase.
Vibration Analysis of Composite Cylindrical Shells Subjected to Electromagnetic and Thermal Fields
Park, Sang-Yun ; Kim, Sung-Kyun ; Choi, Jong-Woon ; Song, Oh-Seop ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 791~799
DOI : 10.5050/KSNVE.2012.22.8.791
In this paper free vibration analysis of symmetric and cross-ply elastic laminated shells based on FSDT was performed through discretization of equations of motion and boundary condition. Structural model of laminated composite cylindrical shells subjected to a combination of magnetic and thermal fields is developed via Hamilton's variational principle. These coupled equations of motion are based on the electromagnetic equations(Faraday, Ampere, Ohm, and Lorenz equations) and thermal equations which are involved in constitutive equations. Variations of dynamic characteristics of composite shells with applied magnetic field, temperature gradient, and stacking sequence are investigated and pertinent conclusions are derived.
An Analysis of Radiation Efficiency of the Simply Supported Rectangular Plate in Water with Consideration of Low Order Cross Modes
Kim, Hyun-Sil ; Kim, Jae-Seung ; Kim, Bong-Ki ; Kim, Sang-Ryul ; Lee, Seong-Hyun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 22, issue 8, 2012, Pages 800~807
DOI : 10.5050/KSNVE.2012.22.8.800
In this paper, radiation efficiency of the plate surround by an infinite rigid baffle is studied. The plate is simply supported and one side is in contact with air, while other side with water. The pressure and normal velocity over the plate surface are assumed as modal summations, from which a set of linear equations is obtained for fluid-structure coupled problem. It is shown that neglect of the cross modes results in overestimation of the radiation efficiency specifically for mid-frequency ranges. Based on the fact that the responses are mainly determined from the first few cross modes in addition to the diagonal terms, a new algorithm is proposed, where banded matrix is iteratively solved in computing radiation efficiency. In numerical examples, it is found that radiation efficiency obtained from banded matrix is in excellent agreement with the one from the full matrix, while computing time is significantly reduced. It is also found that as frequency grows larger, radiation efficiency considering only diagonal terms is a good approximation.