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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
Performance Test of Noise Reducers Installed on Noise Barrier
Kang, Dae-Joon ; Lee, J.W. ; Gu, J.H. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1139~1144
DOI : 10.5050/KSNVN.2007.17.12.1139
The use of noise barrier is being increased to reduce the environmental noise in these days. Also, many noise reducers installed at the top of noise barrier are developed for improving the efficiency of noise reduction. So we evaluate the performance of the noise reducers and compare the results among the others. Results of field tests show that the insertion loss due to the noise reducers is up to 10.6 dB.
A Study on the Vibration Reduction of a Forklift with an Electric Motor
Park, Chul-Jun ; Im, Hyung-Bin ; Chung, Jin-Tai ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1145~1151
DOI : 10.5050/KSNVN.2007.17.12.1145
In this paper, vibration sources of an electric forklift are identified and the forklift vibrations are reduced by structural modification. For vibration identification, vibration signals are measured by an accelerometer when the forklift is moving. These signals are presented in a waterfall plot in order to find the dependency of frequency components on the forklift speed. It is found that main vibration source is tire pattern excitation. From some experiments and finite element analyses, it is also found that resonances occur because the natural frequencies of the forklift exist in usual driving speed range. To shift the natural frequencies outside the driving speed range, the connection parts between main body and loader are modified to increase stiffness. It is verified that considerable amount of vibration are reduced by the structural modification.
A Design of Integral Sliding Mode Suspension Controller to Reject the Disturbance Force Acting on the Suspension System in the Magnetically Levitated Train System
Lee, Jun-Ho ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1152~1160
DOI : 10.5050/KSNVN.2007.17.12.1152
In this paper we deal with a design of integral sliding mode controller to reject the disturbance force acting on the suspension system in the magnetically levitated system which is propelled by the linear induction motor. The control scheme comprises an integral controller which is designed for achieving zero steady-state error under step disturbances, and a sliding mode controller which is designed for enhancing robustness under plant uncertainties. A proper continuous design signal is introduced to overcome the chattering problem. The disturbance force produced by the linear motor is formularized by using a curve fitting of the experimental raw data. Computer simulations show the effectiveness of the designed integral sliding mode controller to reject the disturbance force.
Stability Analysis of Rotating Cantilever Pipe Conveying Fluid with Crack
Son, In-Soo ; Yoon, Han-Ik ; Kim, Dong-Jin ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1161~1169
DOI : 10.5050/KSNVN.2007.17.12.1161
In this paper, the dynamic stability of a rotating cantilever pipe conveying fluid with a crack is investigated by the numerical method. That is, the influence of the rotating angular velocity, mass ratio and crack severity on the critical flow velocity for flutter instability of system are studied. The equations of motion of rotating cantilever pipe are derived by using extended Hamilton's principle. The crack section of pipe is represented by a local flexibility matrix connecting two undamaged pipe segments. The crack is assumed to be in the first mode of fracture and always opened during the vibrations. Generally, the critical flow velocity for flutter is proportional to the rotating angular velocity of a pipe. Also, the critical flow velocity and stability maps of the rotating pipe system for the variation each parameter are obtained.
Performance Evaluation of a Suspension Seat Controller Using ECU-in-the-Loop Simulation
Baek, Woon-Kyung ; Lee, Ji-Woong ; Lee, Jong-Suk ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1170~1178
DOI : 10.5050/KSNVN.2007.17.12.1170
Repeated hardware tests and tuning, investing cost and time, are usually required to assure a satisfactory performance of the suspension seat. In this study, an EILS(ECU-in-the-loop) method was proposed to develop a controller for a semi-active suspension seat with a MR(magneto-rheological) damper. EILS system was developed using a real-time seat dynamics model communicating with ECU hardwares under a closed loop environment utilizing Matlab/Simulink and xPC
. A sky-hook based control algorithm with optimized damping coefficients was verified to reduce the energy consumption and to improve the vibration response performance.
Electromechanical Simulation of Cellulose Based Biomimetic Electro-Active Paper
Jang, Sang-Dong ; Kim, Jae-Hwan ; Kim, Heung-Soo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1179~1183
DOI : 10.5050/KSNVN.2007.17.12.1179
Electro-Active paper(EAPap) is a new smart material that has a potential to be used in biomimetic actuator and sensor. It is made by cellulose that is abundant material in nature. EAPap is fascinating with its biodegradability, lightweight, large displacement, high mechanical strength and low actuation voltage. Actuating mechanism of EAPap is known to be the combined effects of ion migration and piezoelectricity. However, the electromechanical actuation mechanisms are not yet to be established. This paper presents the modeling of the actuation behavior of water infused cellulose samples and their composite dielectric constants calculated by Maxwell-Wagner theory. Electro-mechanical forces were calculated using Maxwell stress tensor method. Bending deflection was evaluated from simple beam model and compared with experimental observation, and which result in good correlation with each other.
Characteristics of Sound Reduction Index through Small Sized Lightweight Panel
Yang, Hong-Seok ; Jeong, Gab-Chul ; Kim, Myung-Jun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1184~1194
DOI : 10.5050/KSNVN.2007.17.12.1184
Recently, framed structure is increasingly being used as apartment structure due to the advantages during remodeling. Therefore, the use of lightweight panel as separating wall is increasing. To construct lightweight panel structures with sound insulation performance appropriate to the conditions of each field, measurement of sound reduction index(SRI) through panel structures should be performed. In this study, measurement of SRI through 46 kinds of panel structures was performed in the condition of various factors such as surface density, air space and absorber. The result showed that SRI of panel structures was generally higher by increasing of surface density. In the case of double panel with no absorber, SRI at below critical frequency was gradually increased according to rise of air space. Double panel with absorber make remarkable improvement in SRI at low frequency, but there is a little difference compared with SRI of double panel with no absorber over critical frequency.
Torque Measurement of Rotating Shaft Using Fiber Bragg Grating Sensors and Rotary Optical Coupler
Lee, Jong-Min ; Hwang, Yo-Ha ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1195~1200
DOI : 10.5050/KSNVN.2007.17.12.1195
Torque of a rotating shaft has been mostly measured by strain gages combined with either a slip ring or telemetry. However, these methods have severe inherent problems like low S/N ratio, high cost, limited number of channels and difficult installation. In this paper, a new method using FBG(fiber bragg grating) sensors and a rotary optical coupler for online non-contact torque monitoring is suggested. FBG sensor can measure both strain and temperature, and has much batter characteristics than those of a strain gage. A rotary optical coupler is a optical connecting device between a rotating shaft and stationary side without any physical contact. It has been devised for transmitting light between a rotating optical fiber and a stationary optical fiber. The proposed method uses this rotary optical coupler to connect FBG sensors on the rotating shaft to instruments at stationary side. And a reference FBG sensor is also applied to compensate the insertion loss change of the rotary optical coupler due to rotation. Three FBG sensors have been fabricated in a single optical fiber. Two FBG sensors are attached on the shaft surface to measure torque and one sensor is installed at the shaft center to compensate the insertion loss change. The torque of a rotating shaft has been successfully measured by the suggested method proving its superior performance potential.
Nondimensional Parametric Study of a Timoshenko Rotating Shaft Subject to Moving Mass and Compressive Axial Forces
Park, Yong-Suk ; Hong, Sung-Chul ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1201~1207
DOI : 10.5050/KSNVN.2007.17.12.1201
The Timoshenko beam theories are used to model the rotating shaft. The nondimensional equations of motion for the rotating shaft subjected to moving mass and compressive axial forces are derived by using Hamilton's principle. Influence of system parameters such as the speed ratio. the mass ratio and the Rayleigh coefficient is discussed on the response of the moving system. The effects of compressive axial forces are also included in the analysis. The results are presented and compared with the available solutions of a rotating shaft subject to a moving mass and a moving load.
FE Modeling for the Transient Response Analysis of a Flexible Rotor-bearing System with Mount System to Base Shock Excitation
Lee, An-Sung ; Kim, Byung-Ok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1208~1216
DOI : 10.5050/KSNVN.2007.17.12.1208
Turbomachinery such as turbines, pumps and compressors, which are installed in transportation systems, including aircrafts, ships, and space vehicles, etc., often perform crucial missions and are exposed to potential dangerous impact environments such as base-transferred shock forces. To protect turbomachinery from excessive shock forces, it may be needed to accurately analyze transient responses of their rotors, considering the dynamics of mount designs to be applied. In this study a generalized FE transient response analysis model, introducing relative displacements, is proposed to accurately predict transient responses of a flexible rotor-bearing system with mount systems to base-transferred shock forces. In the transient analyses the state-space Newmark method of a direct time integration scheme is utilized, which is based on the average velocity concept. Results show that for the identical mount systems considered, the proposed FE-based detailed flexible rotor model yields more reduced transient vibration responses to the same shocks than a conventional simple model, obtained by treating a rotor as concentrated lumped mass, equivalent spring and a damper or Jeffcott rotor model. Hence, in order to design a rotor-bearing system with a more compact light-weighted mount system, preparing against any potential excessive shock, the proposed FE transient response analysis model herein is recommended.
Experimental Evaluation of Buzz, Squeak and Rattle Noise of Vehicle Doors and Its Prevention
Shin, Su-Hyun ; Jung, Sung-Soo ; Cheong, Cheol-Ung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1217~1222
DOI : 10.5050/KSNVN.2007.17.12.1217
With recent advance in automotive noise control engineering reducing major sound sources in the vehicle, customers perceive Buzz, Squeak and Rattle (BSR) as one of important indicators of vehicle quality and durability. As the long-term goal, we expect to establish the integrated design cycle for the reduction of the BSR noise in the early stage of vehicle development. which consist of design, prediction and evaluation procedures. This is possible only with great bulk of experimental data for BSR noise. In this paper, BSR noise is experimentally identified for vehicle doors, which have been traditionally considered as one of main sources of BSR noise. Based on this result, we proposed systematic method for the prevention of BSR noise in the vehicle doors.
Control of Sound Pressure inside a Flow Excited Cavity by Regulation of Vorticity Shedding
Park, Jong-Beom ; Hwang, Cheol-Ho ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1223~1229
DOI : 10.5050/KSNVN.2007.17.12.1223
Flow traveling over a cavity opening forms a vortex due to unstable shear layer and induces an aerodynamic pressure excitation from the diffusion of the vortex convecting out of the trailing edge of the opening. The interaction between the excitation force and the cavity response sustains resonance in the resonator(cavity) and locked-in vortex shedding at the leading edge of the opening. The aerodynamic excitation force can be described from the diffusion of the vortex over the trailing edge and the level of its diffusivity is related to the strength of vorticity seeded at the leading edge. In this study, the control scheme of the internal pressure oscillation was proposed from regulating the vorticity at the leading edge by use of an oscillating spoiler. It was found that the relative motion between the spoiler and the air mass at the cavity opening influenced vorticity strength and the control was achieved by direct feedback of the cavity pressure fluctuation to the actuator.
The Standardization of Sound Quality Evaluation Method for the Vehicle Interior Noise
Park, Sang-Gil ; Lee, Hae-Jin ; Bae, Chul-Yong ; Lee, Bong-Hyun ; Oh, Jae-Eung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1230~1237
DOI : 10.5050/KSNVN.2007.17.12.1230
The vehicle noise is classified into interior and radiated exterior noise. And it influences on consumer's vehicle decision and traffic noise environment very much. In case of the vehicle exterior noise, it is related with traffic noise and in case of the interior noise, it is related with driver's and passenger's sensitivity quality. Because these influenced on drivers and traffic environment, so standards are restricted by the laws and regulated for the measurement. But, the existence standards measuring the only sound pressure level are limit to reflect consumer's sensitive aspects. Therefore in this study, the recent standards and laws were searched about domestic and abroad papers and the testing mode for the sound quality(SQ) evaluation was constructed about the vehicle interior noise. Finally, we aimed at the standard establishment to evaluate the vehicle interior SQ using statistics method.
Root Cause and Countermeasure on the Spike Vibration of a 550MW Class USC(ultra super critical) Steam Turbine
Yang, Seong-Heon ; Kim, Yong-Seok ; Nah, Un-Hak ; Park, Jong-Geun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1238~1245
DOI : 10.5050/KSNVN.2007.17.12.1238
A very abnormal vibration was occurred at the LP(low pressure) turbine continuously during the pre-operation for a 550MW class USC(ultra super critical) steam turbine. This vibration was initiated at the rotating speed of about 3,450 rpm and then the vibration amplitude was highly increased the number by
times with the increase of the rotating speed to the rated speed (3,600 rpm). In this paper, this abnormal vibration named spike vibration. This spike vibration was caused by the rubbing between the rotating bucket tip seal and the lower half of spill strip. Also, this paper presents the mechanism of the spike vibration and the proper method to eliminate this abnormal vibration problem. This result would be good practice to find the solution of similar high vibration in the USC steam turbines for power plant as well as industrial rotating machineries.
Plate Spring Design of a Micro Actuator Using Topology-parameter Optimization
Lee, Jong-Jin ; Lee, Ho-Cheol ; Yoo, Jeong-Hoon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1246~1253
DOI : 10.5050/KSNVN.2007.17.12.1246
The recent issue of optical pickup actuators is to apply optical storage devices to mobile devices such as a cellular phone and PDA. It requires actuators to become smaller than conventional types. As the size becomes smaller, the magnetic force is reduced and the assembly of optical pickup actuators becomes more difficult. In addition, its dynamic characteristics are changed. In this paper, methods to improve magnetic forces and dynamic characteristics are suggested and the optimal result of the plate spring design is obtained. A diamond shape magnet and the fine pattern coil (FPC) are used to improve magnetic forces and damping elements are attached to decrease the peak magnitude of the mode instead of using structural damping, mostly for the purpose of improving the accuracy of the finite element simulation. To get more stable dynamic characteristics than conventional ones, a plate spring is applied to the optical pickup actuator and it is optimized with topology and parameter optimization to obtain the concept and the detail design, respectively.
The Source Identification of Noise Using Characteristics of Transmission and the Reduction of Interior Noise for Changing the Input Factor
Lee, You-Yub ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 12, 2007, Pages 1254~1261
DOI : 10.5050/KSNVN.2007.17.12.1254
The structure has several types of noise and booming noise of a vehicle is usually caused by the vibration of the vehicle's body transmitted from the engine through the mounting system. Vector synthesis analysis is performed to predict the booming noise when the characteristic of the engine mounting system is changed., i.e., when magnitudes and phases of vibratory forces after the mounts are altered. To use this method effectively, the concept of Multi-dimensional-analysis and Experimental Design are introduced to identify the contributions of each vibration sources and transmission paths to interior noise. It was used 3inputs/1output system and found the magnitudes and phases of the forces for minimizing the noise. Finally, the synthesized interior booming noise level is predicted by the vector synthesis diagram. It is shown that the vector synthesis method can be used to obtain the optimum design characteristic of the mounting system to control the interior booming noise of a vehicle.