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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 26, Issue 4 - Aug 2016
Volume 26, Issue 3 - Jun 2016
Volume 26, Issue 2 - Apr 2016
Volume 26, Issue 1 - Jan 2016
Selecting the target year
Pattern Analysis of Noise Radiated from Household Refrigerator
Kong, Kyung-Soo ; Jeong, Weui-Bong ; Kim, Tae-Hoon ; Shin, Dae-Sik ; Ahn, Se-Jin ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 121~129
DOI : 10.5050/KSNVE.2016.26.2.121
The noise pattern of a household refrigerator is dependent on the characteristics of its operating cycle which is repeated with a specific pattern depending on various parameters, such as room temperature and performance of its mechanical parts. Analysis of noise pattern is essential prior to evaluation of sound quality of a refrigerator. In this study, 14 units of refrigerator were classified into 4 types according to noise pattern and sort of mechanical part, which helps to analyze characteristics of refrigerator noise. Sound quality metrics(loudness, sharpness, roughness, and fluctuation strength) were calculated to compare noise pattern of the 4 types of refrigerator. The results of this study can be useful to decide noise performance of refrigerator.
Floor Impact Noise Level for Concrete Slab Integrated with Floor Finishing Layers
Mun, Dae Ho ; Oh, Yang Ki ; Jeong, Gab Cheol ; Park, Hong Gun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 130~140
DOI : 10.5050/KSNVE.2016.26.2.130
Floating floor is most commonly used at apartment houses in Korea for thermal insulation and reducing impact noise. But it in proven that the floating floor is not effective for reducing the floor impact noise in low frequency range. In most cases, impact sound pressure level under 63 Hz frequency band were actually increased by the resonance of resilient material, lightweight concrete and the finishing mortar installed on it. In this paper, an integrated floor system consist of 70 mm light weight concrete and 40 mm finishing mortar successively installed on the concrete slab was suggested to avoid the resonance. Integrated floor system increases total flexural stiffness and mass per unit area. The natural frequencies of first and second vibration mode were increased and acceleration response and floor impact sound level was decreased in all measurement range.
Numerical Investigation of Cavitation Flow Around Hydrofoil and Its Flow Noise
Kim, Sanghyeon ; Cheong, Cheolung ; Park, Warn-Gyu ; Seol, Hanshin ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 141~147
DOI : 10.5050/KSNVE.2016.26.2.141
Underwater cavitation is one of the most important issues because it causes not only vibration and erosion of submerged bodies but also significant flow noise problems. In this paper, flow noise due to cavitation flows around the NACA66 MOD hydrofoil is numerically investigated. The cavitation flow simulation is conducted using the Reynolds-Averaged Navier-Stokes equations based on finite difference methods. To capture the cavitation phenomena accurately and effectively, the homogeneous mixture model with the Merkle's cavitation model is applied. The predicted results are compared with available experimental data in terms of pressure coefficients and volume fraction, which confirms the validity of numerical results. Based on flow field analysis results, hydro-acoustic noise field due to the cavitation flow is predicted using the Ffowcs-Williams and Hawkings equation derived from the Lighthill's acoustic analogy. The typical lift dipole propagation patterns are identified.
Improvement of an Ultrasonic Transducer for Measuring Both Flow Velocity and Pipe Thickness
Kim, Ju Wan ; Kim, Jin Oh ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 148~156
DOI : 10.5050/KSNVE.2016.26.2.148
The paper deals with improvement of a piezoelectric ultrasonic transducer for measuring both pipe thickness and flow velocity. The transducer structure is based on the conventional transducers for measuring flow velocity by obliquely transmitting ultrasonic waves to the flow direction. The transducer invented earlier for measuring flow velocity and pipe thickness had an advantage of including only one piezoelectric disc, but for the thickness measurement the ultrasonic wave had to be reflected twice in a wedge material to be transmitted vertically to a pipe, and thus the wave signal was too weak. The transducer has been improved to transmit waves for thickness measurement vertically to a pipe without any prior reflection by electrically connecting two piezoelectric discs, one for flow velocity and the other for pipe thickness measurement. By comparing the measured results of specimen thickness with the improved transducer and conventional transducers, the accuracies of the improved one have been evaluated in the pipe thickness measurements.
A Study on Vibration Control Performance of Macpherson Type Semi-Active Suspension System
Dutta, Saikat ; Han, Chulhee ; Lee, TaeHoon ; Choi, Seung-Bok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 157~164
DOI : 10.5050/KSNVE.2016.26.2.157
The paper studies a comparison analysis of semi-active control strategies for a Macpherson strut type suspension system consisting of MR(magneto-rheological) damper. As a first step, in order to formulate governing, a dynamic full model of a Macpherson strut is developed considering the kinematics. The nonlinear equation of motion of the strut is then linearized around the equilibrium point. A new adaptive moving sliding model controller is developed for fast response of the system. A newly proposed adaptive moving sliding mode control strategy is then compared with conventional sliding mode controller and skyhook controller. The comparison is made for two different types of road inputs; bump and random road profiles showing superior vibration control performance in time and frequency domains.
Design and Analysis of Above Knee Prosthetic Leg Using MR Damper
Park, Jinhyuk ; Kang, Je-Won ; Choi, Seung-Bok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 165~171
DOI : 10.5050/KSNVE.2016.26.2.165
A prosthetic knee for above-knee (AK) amputee is categorized into passive and active type. The passive prosthetic knee is generally made by elastic material. Although AK amputee can easily walk by using passive prosthetic leg, knee joint motions are not similar to ordinary persons. The active prosthetic leg can control the knee angle owing to the actuator and microprocessor. However, the active type is not cost-effective and the stability may be lost due to the malfunction of sensors. In order to resolve these disadvantages of passive and active type, a semi-active prosthetic knee which can control the knee angle is proposed in this work. The proposed semi-active one requires a less input energy but provides active type performance. In order to achieve this goal, in this work, a semi-active prosthetic knee using magneto-rheological (MR) damper for AK amputees is designed. The MR damper can support the weight of body by using less energy than actuator of active prosthetic. It can control knee angle by inducing the magnetic field at the time of stance phase. This salient characteristic is evaluated and presented in this work.
The Effect of the Number of Vibration Modes on the Application of the Location Template Matching(LTM) Method
Shin, Kihong ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 172~178
DOI : 10.5050/KSNVE.2016.26.2.172
The location template matching (LTM) method is a technique of identifying an impact location on a structure, and is often applied to structural health monitoring and large scale human-computer interface (HCI) systems. The LTM method utilizes a certain measure of similarity between two time signals. The correlation coefficient is most widely used for this purpose, and the group delay based method is recently proposed to improve the accuracy of finding the best matching pair of signals. In practice, one of key essential consideration for implementing the LTM method is to guarantee that a sufficient number of vibration modes must be contained in the measured signal, and yet the lower sampling rate is needed for a real-time implementation. In this paper, the properties of correlation coefficient and group delay with respect to the number of vibration modes are investigated. A few important results are obtained through extensive computer simulations and experiments. If the number of vibration modes contained in the measured signal is more than four it is sufficient for the correlation based LTM method, while the group delay based LTM method requires smaller number of vibration modes.
Dynamic Analysis of Cracked Timoshenko Beams Using the Transfer Matrix Method
Kim, Jung Ho ; Kwak, Jong Hoon ; Lee, Jung Woo ; Lee, Jung Youn ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 179~186
DOI : 10.5050/KSNVE.2016.26.2.179
This paper presents a numerical method that can evaluate the effect of crack for the in-plane bending vibration of Timoshenko beam. The method is a transfer matrix method that the element transfer matrix is deduced from the element dynamic stiffness matrix. An edge crack is expressed as a rotational spring, and then is formulated as an independent transfer matrix. To demonstrate the accuracy of this theory, the results computed from the present are compared with those obtained from the commercial finite element analysis program. Based on these comparison results, a parametric study is performed to analyze the effects for the size and locations of crack.
Study on Performances of the Lever Type Anti-resonance Vibration Isolator
Yun, Jong-Hwan ; Kim, Gi-Woo ; Lee, Hyeongill ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 187~194
DOI : 10.5050/KSNVE.2016.26.2.187
Parametric study on the lever type dynamic anti-resonance vibration isolator (DAVI) is executed to introduce the system in the path of vibration transmission for the vibratory response attenuation. The effects of inertia and location of the lever on the system performances are investigated using FEA. The effects of other parameters such as ratio of lever lengths, ratio of masses and the location of pivot are studied with analytical approach. According to the results, all the parameters except lever location affect the system response in their own ways. Consequently, the optimal lever type DAVI for translational or rotational system can be efficiently designed by selecting system parameters using the procedure introduced in this study.
Implementation of Active Sound Enrichment Control for Improving Engine Sound Quality Inside the Cabin of a Passenger Car
Lee, Young-Sup ; Kim, Jeakwan ; Ryu, Seokhoon ; Kim, Seonghyeon ; Park, Dong Chul ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 195~202
DOI : 10.5050/KSNVE.2016.26.2.195
In this study, a concept of active sound enrichment (ASE) control system was implemented and demonstrated for improving engine sound quality inside the cabin of a passenger car during acceleration. Unlike the active noise control cancels the noise for disturbance rejection, the ASE adds additional sound to the noise for tracking control. This approach requires a new algorithm to provide additional artificial sound to the original engine sound using active control strategy to achieve a target sound profile, which is predefined to satisfy required interior sound quality. The ASE algorithm was implemented in a digital controller dSPACE DS1401 and real-time control experiment was accomplished in an actual car. The ASE control results show that the actively enriched sound of each engine order against RPM tracks the target profiles precisely and quickly and improves the discontinuity, the level ratios and the sound pressure level of each engine order. Thus it is anticipated the ASE system can be applied for the improvement of the engine sound quality inside the cabin during acceleration.
Numerical Analysis of Added Mass Coefficient for Outer Tubes of Tube Bundle in a Circular Cylindrical Shell
Yang, Keum-Hee ; Ryu, Ki-Wahn ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 203~209
DOI : 10.5050/KSNVE.2016.26.2.203
According to the wear detection history for the steam generator tubes in the nuclear power plant, the outer tubes inside the steam generator have more problems on the flow-induced vibration than inner tubes. Many researchers and engineers have used a specified added mass coefficient for a given tube array during the design stage of the steam generator even though the coefficient is not constant for entire tube in cylindrical shell. The aim of this study is to find out the distribution of added mass coefficients for each tube along the radial location. When numbers of tubes inside a cylindrical shell are increased, values of added mass coefficients are also increased. Added mass coefficients at outer tubes are less than those of inner tubes and they are decreased with increasing the gap between the outermost tube and the cylindrical shell. It also turns out when the gap between the outermost tube and the cylindrical shell approaches infinite value, the added mass coefficient converges to an asymptotic value of given tube array in a free fluid field.
Ride Comfort Analysis of Passenger Vehicle Featuring ER Damper with Different Tire Pressure
Sung, Kum-Gil ; Choi, Seung-Bok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 210~216
DOI : 10.5050/KSNVE.2016.26.2.210
In this work, performance analysis to improve ride comfort of an ER (electrorheological) fluid damper for a mid-sized passenger vehicle in terms of tire pressure is presented. An ER damper by considering specification for a mid-sized commercial passenger vehicle is proposed and mechanically designed. After manufacturing and assembling the proposed ER damper with design parameters, their performance such as field-dependent damping forces are experimentally measured. A quarter-vehicle ER ECS (Electronic Control Suspension) system consisting of the ER damper, sprung mass, spring, sky-hook controller and tire is constructed to analysis the ride comfort performances. Vertical tire stiffness with different tire pressure is experimentally measured and investigated. In addition, ride comfort analysis such as vertical acceleration root mean square (RMS) of sprung mass is investigated under bump road using quarter-vehicle test equipment.
Analysis of Vibration for the Pre-twisted Beam Considering the Effect of Rotary Inertia Using the Transfer Matrix Mathod
Lee, Jung Youn ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 26, issue 2, 2016, Pages 217~224
DOI : 10.5050/KSNVE.2016.26.2.217
In this study, a transfer matrix method (TMM) for a twisted uniform beam considering the effect of rotary inertia is developed, and the differential equation and the displacements and forces are derived from Hamilton's principle. The particular transfer matrix is derived by applying the distributed mass and transcendental function while using a local coordinate system. In addition, the results obtained from this method are independent for a number of subdivided elements, and this method can determine the exact solutions for the free vibration characteristics of a twisted uniform Rayleigh beam. To validate the accuracy of the proposed TMM, the computed results are compared with those reported in the existing literature, and the comparison results indicate notably good agreement. In addition, the method is used to investigate the effects of rotary inertia for a twisted beam.