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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 18, Issue 12 - Dec 2008
Volume 18, Issue 11 - Nov 2008
Volume 18, Issue 10 - Oct 2008
Volume 18, Issue 9 - Sep 2008
Volume 18, Issue 8 - Aug 2008
Volume 18, Issue 7 - Jul 2008
Volume 18, Issue 6 - Jun 2008
Volume 18, Issue 5 - May 2008
Volume 18, Issue 4 - Apr 2008
Volume 18, Issue 3 - Mar 2008
Volume 18, Issue 2 - Feb 2008
Volume 18, Issue 1 - Jan 2008
Selecting the target year
Non-linearity Characteristics Consideration of the Disc Spring Under Shock Using Numerical Analysis
Bang, Seung-Woo ; Lee, Hae-Jin ; Sim, Hyun-Jin ; Park, Sang-Gil ; Lee, Jung-Youn ; Oh, Jae-Eung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 153~159
DOI : 10.5050/KSNVN.2008.18.2.153
General coil spring has linearity. However, disc spring has non-linearity so that using this non-linearity disc spring can be designed to do shock-absorbing in cases we need because shock response also has non-linearity. By changing the shape and stacking number, it is satisfactory with response of displacement, velocity and acceleration. Conventionally, disc spring was used to control the vibration against huge load and limited space. However, it is limitedly used because of difficulty of the designing guidance. Therefore, disc spring is needed to study further in order to apply it widely. Response of disc spring is compared to response of coil spring by changing
ratio with computer simulation and the usage of disc spring is increased through analysis of effect of design factors. The purpose of this paper is that the shock response of disc spring is calculated through numerical simulation and effect of
and stiffness is analyzed to broad usage so that design factor of disc spring is presented.
Stability of Nonlinear Oscillations of a Thin Cantilever Beam Under Parametric Excitation
Bang, Dong-Jun ; Lee, Gye-Dong ; Jo, Han-Dong ; Jeong, Tae-Gun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 160~168
DOI : 10.5050/KSNVN.2008.18.2.160
This paper presents the study on the stability of nonlinear oscillations of a thin cantilever beam subject to harmonic base excitation in vertical direction. Two partial differential governing equations under combined parametric and external excitations were derived and converted into two-degree-of-freedom ordinary differential Mathieu equations by using the Galerkin method. We used the method of multiple scales in order to analyze one-to-one combination resonance. From these, we could obtain the eigenvalue problem and analyze the stability of the system. From the thin cantilever experiment using foamax, we could observe the nonlinear modes of bending, twisting, sway, and snap-through buckling. In addition to qualitative information, the experiment using aluminum gave also the quantitative information for the stability of combination resonance of a thin cantilever beam under parametric excitation.
Optimal Design of Magnetorheological Shock Absorbers for Passenger Vehicle via Finite Element Method
Sung, Kum-Gil ; Choi, Seung-Bok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 169~176
DOI : 10.5050/KSNVN.2008.18.2.169
This paper presents optimal design of controllable magnetorheological(MR) shock absorbers for passenger vehicle. In order to achieve this goal, two MR shock absorbers (one for front suspension; one for rear suspension) are designed using an optimization methodology based on design specifications for a commercial passenger vehicle. The optimization problem is to find optimal geometric dimensions of the magnetic circuits for the front and rear MR shock absorbers in order to improve the performance such as damping force as an objective function. The first order optimization method using commercial finite element method(FEM) software is adopted for the constrained optimization algorithm. After manufacturing the MR shock absorbers with optimally obtained design parameters, their field-dependent damping forces are experimentally evaluated and compared with those of conventional shock absorbers. In addition, vibration control performances of the full-vehicle installed with the proposed MR shock absorbers are evaluated under bump road condition and obstacle avoidance test.
Dynamic Stability of Elastically Restrained Cantilever Pipe Conveying Fluid with Crack
Son, In-Soo ; Yoon, Han-Ik ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 177~184
DOI : 10.5050/KSNVN.2008.18.2.177
The dynamic stability of elastically restrained cantilever pipe conveying fluid with crack is investigated in this paper. The pipe, which is fixed at one end, is assumed to rest on an intermediate spring support. Based on the Euler-Bernoulli beam theory, 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 a crack severity and position, mass ratio and the velocity of fluid flow on the stability of a cantilever pipe by the numerical method are studied. Also, the critical flow velocity for the flutter and divergence due to variation in the support location and the stiffness of the spring support is presented. The stability maps of the pipe system are obtained as a function of mass ratios and effect of crack.
Optimal Layout Design of Frequency- and Temperature-dependent Viscoelastic Materials for Maximum Loss Factor of Constrained-Layer Damping Beam
Lee, Doo-Ho ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 185~191
DOI : 10.5050/KSNVN.2008.18.2.185
Optimal damping layout of the constrained viscoelastic damping layer on beam is identified with temperatures by using a gradient-based numerical search algorithm. An optimal design problem is defined in order to determine the constrained damping layer configuration. A finite element formulation is introduced to model the constrained layer damping beam. The four-parameter fractional derivative model and the Arrhenius shift factor are used to describe dynamic characteristics of viscoelastic material with respect to frequency and temperature. Frequency-dependent complex-valued eigenvalue problems are solved by using a simple re-substitution algorithm in order to obtain the loss factor of each mode and responses of the structure. The results of the numerical example show that the proposed method can reduce frequency responses of beam at peaks only by reconfiguring the layout of constrained damping layer within a limited weight constraint.
Dynamic Analysis of a Tilting Actuator for a Projection TV
Im, Hyung-Bin ; Park, Chul-Jun ; Chung, Jin-Tai ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 192~198
DOI : 10.5050/KSNVN.2008.18.2.192
A dynamic analysis of a tilting actuator for a projection TV is presented in this study. Severe vibration of a tilting actuator deteriorates the video quality of a projection TV. For this reason, a dynamic analysis of the tilting actuator system is essential to improve the video quality. The dynamic behaviors of the mirror reactive-type tilting actuator are examined in order to obtain design requirements of the lens transmissive-type tilting actuator. Based on these design requirements, a basic design is performed for the lens transmissive-type tilting actuator. With the basic design, the dynamic characteristics of the lens transmissive-type actuator are investigated by the finite element analysis After the prototype of the actuator is manufactured, the dynamic behaviors of the prototype are examined by experiments. As a result of this study, a new design for the hinge configuration of the actuator is suggested for better performance.
HRTF-field Reproduction for Robust Virtual Source Imaging
Choi, Joung-Woo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 199~207
DOI : 10.5050/KSNVN.2008.18.2.199
A hybrid technique that combines the advantages of binaural reproduction and sound field reproduction technique is proposed. The concept of HRTF-field, which is defined as the set of HRTFs corresponding to the various head dislocations, enables us to realize virtual source imaging over a wide area. Conventional binaural(
) reproduction system is redefined as a MIMO system composed of multiple control sources and multiple head locations, and HRTF variations corresponding to various head movement are quantified. Through the direct control of HRTF-field, reproduction error induced by head dislocation can be minimized in least-square-error sense, and consequential disturbances on the virtual source image can be reduced within a selected area. Simple lateralization examples are investigated, and the reproduction error of the proposed technique is compared to that of higher-order Ambisonics.
Structural Modification for the Performance Improvement of a Grain Sorting Machine
Kim, Sung-Hyun ; Lee, Kyu-Ho ; Im, Hyung-Bin ; Chung, Jin-Tai ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 208~214
DOI : 10.5050/KSNVN.2008.18.2.208
This paper presents a structural modification for the performance improvement of a grain sorting machine. The grain sorting machine is used to sort abnormal grains from normal grains such as rice or wheat. Vibration is one of main causes to deteriorate the sorting performance of the machine. Based on the finite element analysis and the experimental modal testing, the vibration characteristics were investigated for the sorting machine. Furthermore, in order to improve the sorting performance of the machine, the frame, chute and base plate of the sorting machine were modified by using the results of the vibration analysis.
In-plane Free Vibration Analysis of Parabolic Arches with Hollow Section
Lee, Tae-Eun ; Lee, Byoung-Koo ; Lee, Jae-Young ; Yoon, Hee-Min ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 215~223
DOI : 10.5050/KSNVN.2008.18.2.215
The differential equations governing free vibrations of the elastic arches with hollow section are derived in polar coordinates, in which the effect of rotatory inertia is included. Natural frequencies is computed numerically for parabolic arches with both clamped ends and both hinged ends. Comparisons of natural frequencies between this study and reference are made to validate theories and numerical methods developed herein. The lowest four natural frequency parameters are reported, with the rotatory inertia, as functions of three non-dimensional system parameters: the breadth ratio, the thickness ratio and the rise to span length ratio.
Active Vibration Control of Structure Using Active Tuned Mass Damper and Modified PPF Controller
Kim, Ki-Young ; Kwak, Moon-K. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 224~230
DOI : 10.5050/KSNVN.2008.18.2.224
This paper is concerned with the active vibration control of building structure by means of the active tuned mass damper and the modified positive position feedback controller. To this end, one-degree-of-freedom spring-mass-damper system equipped with ATMD is considered. The stability condition for the addressed system when applying the proposed PPF controller is derived by Routh-Hurwitz stability criterion. The stability condition shows that the modified PPF controller is absolutely stable if the controller gain is positive. so that the modified PPF controller can be used without difficulty. Theoretical study shows that the modified PPF controller can effectively suppress vibrations as the original PPF controller does in smart structure applications. To investigate the validity of the modified PPF controller, a simple experimental structure with an ATMD system driven by DC motor was built. The modified PPF control algorithm was implemented on Atmel 128 microcontroller. The experimental result shows that the modified PPF controller can also suppress vibrations for the real structure.
Fast Convolution Method Using Real-time Masking Effects in Sound Reverberator
Shin, Min-Cheol ; Wang, Se-Myung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 231~237
DOI : 10.5050/KSNVN.2008.18.2.231
With the advent of sound field simulator, many sound fields have been reproduced by obtaining the impulse responses of specific acoustic spaces like famous concert hall, opera house. This sound field reproduction has been done by the linear convolution operation between the sound input signal and the impulse response of certain acoustic space. However, the conventional finite impulse response based linear convolution operation always makes real-time implementation of sound field generator impossible due to the large amount of computational burden. This paper introduces the fast convolution method using perceptual redundancy in the processed signals, input audio signal and room impulse response. Temporal and spectral real-time masking blocks are implemented in the proposed convolution structure. It reduces the computational burden of convolution methods for real-time implementation of a sound field generator. The conventional convolutions are compared with the proposed one in views of computational burden and sound quality. In the proposed method, a considerable reduction in the computational burden was realized with acceptable changes in sound quality.
A Case Study on the Vibration by Fluid Induced Instability at Large Steam Turbine-generator
Han, Seung-Woo ; Roh, Cheol-Woo ; Yoo, Mu-Sang ; Kim, In-Chul ; Joo, In-Gouk ; Kim, Myong-Shik ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 238~246
DOI : 10.5050/KSNVN.2008.18.2.238
This case study refers to turbine-generator with retrofitted turbine rotor. Vibration problem occurring after the retrofit was mainly due to high vibration from exciter side. However, repeated test run and operation during scheduled maintenance caused high vibration from generator bearing, and post-overhaul test run before turbine vibration correction caused oil whip on the bearing. This case study shows how to analyze vibration condition of high turbine generator vibration detected during the post-overhaul test run and vibration condition of offline and online data to reflect it on establishing maintenance schedule and overhaul correction procedure. Vibration data could be acquired during steady load operation or even with varying speed and load. Each data is important for machinery condition evaluation. This case study shows that the vibration data during extreme condition is the key factor in analysis, which helps to find the machinery problem.
Evaluation of the Dynamic Stiffness and Heavy-weight Floor Impact Sound Reduction by Composition of Resilient Materials
Kim, Kyoung-Woo ; Jeong, Gab-Cheol ; Sohn, Jang-Yeul ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 247~254
DOI : 10.5050/KSNVN.2008.18.2.247
Resilient materials are generally used for the floating floors to reduce the floor impact sound. Dynamic stiffness of resilient material, which has the most to do with the floor impact sound reduction. The resilient materials available in Korea include EPS(styrofoam), recycled urethane types, EVA(ethylene vinylacetate) foam rubber, foam PE(polyethylene). glass fiber & rock wool, recycled tire, foam polypropylene. compressed polyester, and other synthetic materials. In this study, we tested dynamic stiffness of resilient material and floor impact sound reduction characteristic to a lot of kinds of resilient materials. It was found that dynamic stiffness of multi-layered damping material could be estimated if know value of each layer that compose whole structure. And the test showed that the amount of the heavy-weight impact sound reduction appeared by being influenced from this dynamic stiffness of resilient material. The dynamic stiffness looked like between other resilient materials, a similar to the amount of the heavy-weight impact sound reduction was shown.
Performance Evaluation of Decentralized Control Algorithm of a Full-scale 5-story Structure Installed with Semi-active MR Damper Excited by Seismic Load
Youn, Kyung-Jo ; Park, Eun-Churn ; Lee, Heon-Jae ; Moon, Seok-Jun ; Min, Kyung-Won ; Jung, Hyung-Jo ; Lee, Sang-Hyun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 255~262
DOI : 10.5050/KSNVN.2008.18.2.255
In this study, seismic response control performance of decentralized response-dependent MR damper which generates the control force using only the response of damper-installed floor, was experimentally investigated through the tests of a full-scale structure installed with large MR dampers. The performance of the decentralized control algorithm was compared to those of the centralized ones such as Lyapunov, modulated homogeneous friction, and clipped-optimal control. Hybrid mass damper were controlled to induce seismic response of the full-scale structure under El Centro earthquake. Experimental results indicated that the proposed decentralized MR damper provided superior or equivalent performance to centralized one in spite of using damper-installed floor response for calculating input voltage to MR damper.
Evaluation for the Capability of the Sound Insulation and Experimental Analysis for the Improvement of the Sound Insertion Loss of the Air Conditioner-cabinet Considering the Thickness and Aperture of the Partition
Han, Hyung-Suk ; Jung, Woo-Seoung ; Mo, Jin-Yong ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 2, 2008, Pages 263~271
DOI : 10.5050/KSNVN.2008.18.2.263
Compressor radiated noise is one of the dominant noise for the outdoor unit of the air conditioner. Therefore, air conditioner makers are trying to reduce it continuously. Even though noise absorption and isolation technology are one of the important parts for reducing the noise from the compressor, it is usually treated to the substitute technology when the noise from the compressor is very difficult to reduce by the compressor noise control only. In this paper, we focus on the property of the sound insulation for the cabinet and measure it applying the theory of the sound transmission loss and insertion loss of the simple enclosure. The insertion loss is evaluated by the experiments according to the thickness and the aperture of the partition in the cabinet.