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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 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
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Active Control of Vibration Isolation Table Using Air-spring
An, Chae-Hun ; Yim, Kwang-Hyeok ; Jin, Kyong-Bok ; Rim, Kyung-Hwa ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 565~571
DOI : 10.5050/KSNVN.2007.17.7.565
In the process of accurate manufacture and measurement, it is necessarily required to isolate external or internal vibration due to external disturbance and internal actuators. The higher vibration isolation system gets damping around resonance, the better it is generally. This paper analyzes the performance of an existing passive air-spring for vibration isolation table by using experiment and simulation. Optimal design for a passive air spring can be obtained by tuning the size of the orifice. Also design for an active isolation system is carried out by applying PID controller and considering non-linearity of pneumatic characteristics with help of look-up table. We have developed the active vibration isolation table with the better isolation performance.
An Estimation on Two Stroke Low Speed Diesel Engines' Shaft Fatigue Strength due to Torsional Vibrations in Time Domain
Lee, Don-Chool ; Kim, Sang-Hwan ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 572~578
DOI : 10.5050/KSNVN.2007.17.7.572
Two stroke low speed diesel engines are widely used for marine propulsion or as power plant prime mover. These engines have many merits which includes higher thermal efficiency, mobility and durability. Yet various annoying vibrations occur sometimes in ships or at the plant itself. Of these vibrations, torsional vibration is very important and dictates a careful investigation during the engme's initial design stage for safe operation. With the rule and limit on torsional vibration in place, shaft strength fatigue due to torsional vibration however demands further analysis which possibly can be incorporated in the classification societies' rule and limit. In addition, the shaft's torsional vibration stresses can be calculated equivalently from accumulated fatigue cycles number due to transient torsional vibration in time domain. In this paper, authors suggest a new estimation method combined with Palmgren-Miner equation. A 6S70MC-C (
) engine for ship propulsion was selected as a case study. Angular velocity was measured, instead of shaft's strain, for simplified measurement and it was converted to torsional vibration stress for accumulated fatigue cycle numbers in shafting life time. Likewise, the accumulated fatigue calculation was compared with shaft fatigue strength limit. This new method can be further realized and confirmed in ship with two stroke low speed diesel engine.
Analytical Method to Analyze the Effect of Tolerance on the Modal Characteristic of Multi-body Systems in Dynamic Equilibrium
Kim, Bum-Suk ; Yoo, Hong-Hee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 579~586
DOI : 10.5050/KSNVN.2007.17.7.579
Analytical method to analyze the effect of tolerance on the modal characteristic of multi-body systems in dynamic equilibrium position is suggested in this paper. Monte-Carlo method is conventionally employed to perform the tolerance analysis. However, Monte-Carlo method spends too much time for analysis and has a greater or less accuracy depending on sample condition. To resolve these problems, an analytical method is suggested in this paper. Sensitivity equations for damped natural frequencies and the transfer function are derived at the dynamic equilibrium position. By employing the sensitivity information of mass, damping and stiffness matrices, the sensitivities of damped natural frequencies and the transfer function can be calculated.
Vibration Suppression of Hull Structure Using MFC Actuators
Sohn, Jung-Woo ; Kim, Heung-Soo ; Choi, Seung-Bok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 587~595
DOI : 10.5050/KSNVN.2007.17.7.587
Performance evaluation of advanced piezoelectric composite actuator is conducted with its application of structural vibration control. Characteristics of MFC(macro fiber composite) actuator are investigated by comparing traditional piezoceramic patch actuator. Finite element modeling is used to obtain equations of motion and boundary effects of smart hull structure with MFC actuator. Dynamic characteristics of the smart hull structure are studied through modal analysis and experimental investigation. LQG control algorithm is employed to investigate active damping of hull structure. It is observed that vibration of hull structure is suppressed effectively by the MFC actuators.
Effects of Geometric Configuration on the Vibro-acoustic Characteristics of Radial Vibration of an Annular Disc
Lee, Hyeong-Ill ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 596~604
DOI : 10.5050/KSNVN.2007.17.7.596
This article investigates the effects of geometric configuration on the vibro-acoustic characteristics of in-plane vibration of a thick annular disc. Disc thickness and outer radius for a given inner radius are selected as independent variables having reasonable ranges. Variations in structural eigensolutions for radial modes are investigated using pre-developed analytical method. Based on these data, far-field sound pressure distributions due to the modal vibrations for a given geometry are also calculated using an analytical solution. Modal sound powers and radiation efficiencies are calculated from the far-field sound pressure distributions and vibratory velocity distributions on the radial surfaces. Based on the results explained above, the geometric configuration that minimizes modal sound radiations in a given frequency range is determined. Finally sound power and radiation efficiency spectra for a unit harmonic force from the selected geometric configuration are obtained from structural and acoustic modal data using the modal expansion technique. Multi-modal sound radiations of the optimized disc that are obtained using proposed analytical methods are confirmed with numerical results. Using the procedure introduced in this article, sound radiation due to in-plane modes within a specific frequency range can be minimized by the disc geometry modifications in a comprehensive and convenient manner.
Stability Analysis of Cracked Cantilever Beam with Tip Mass and Follower Force
Son, In-Soo ; Yoon, Han-Ik ; Ahn, Tae-Su ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 605~610
DOI : 10.5050/KSNVN.2007.17.7.605
In this paper a dynamic behavior(natural frequency) of a cracked cantilever beam subjected to follower force is presented. In addition, an analysis of the flutter and buckling instability of a cracked cantilever beam subjected to a follower compressive load is presented. Based on the Euler-Bernoulli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The vibration analysis on such cracked beam is conducted to identify the critical follower force for flutter instability based on the variation of the first two resonant frequencies of the beam. Besides, the effect of the crack's intensity and location on the flutter follower force is studied. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations.
Emotional Evaluation According to the Changes of Visual and Auditory Landscape Elements in Residential Areas
Shin, Yong-Gyu ; Jeon, Ji-Hyeon ; Jang, Gil-Soo ; Kim, Sun-Woo ; Kook, Chan ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 611~616
DOI : 10.5050/KSNVN.2007.17.7.611
This study aims to clarify differences among the responses of users depending on variations in audio-visual landscape elements used to create amenities in residential areas. For the purpose, a laboratory experiment was performed to evaluate the emotions of subjects. As a result of subjective evaluation, it was found that the emotions of subjects were more significantly promoted in providing both sounds and images at the same time, than in providing images alone. In addition, as a result of comparing the variables of relativistic energy alpha waves have by measuring their brain waves, it was seen that alpha waves increased when providing harmonious sound sources with images, except for specific sound sources. Thus, it is considered that provision of sound sources capable of promoting human emotions can contribute greatly to improving the value of space for the sake of comfortable housing environment.
Control Performance of Hybrid Mount Using Electromagnetic Actuator and PZT Actuator
Paeng, Yong-Seok ; Yook, Ji-Yong ; Moon, Seok-Jun ; Choi, Seung-Bok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 617~623
DOI : 10.5050/KSNVN.2007.17.7.617
This paper presents an active vibration control of a dynamic system using hybrid mount which consists of elastic rubber-piezostack actuator and elastic rubber-electromagnetic actuator, respectively. After identifying stiffness, damping properties of the elastic rubber, PZT actuator and electromagnetic element, a mathematical model of the hybrid mount is established. The mount model is then incorporated into the dynamic system and the governing equation of motion is obtained in a state space. A sliding mode controller is designed in order to actively attenuate the vibration of the system. Control responses such as acceleration and transmitted force of the dynamic system are experimentally evaluated and presented in time and frequency domains.
Transient Power Flow Analysis of Beam and Plate
Hwang, Dae-Woong ; Seo, Seong-Hoon ; Kwon, Hyun-Wung ; Hong, Suk-Yoon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 624~631
DOI : 10.5050/KSNVN.2007.17.7.624
PFA (power flow analysis) has been recognized as a useful method in vibration analysis of medium-to-high frequency ranges. Until now, PFA method has been developed for steady-state vibration problems. In this paper, PFA method has been expanded to transient problem. New energy governing equations are derived considering time dependent terms in beam and plate. Analytic solutions of those equations are found in simple beam and plate, and are verified by comparing with modal solutions.
Dynamic Characteristics of High-speed Railway Steel Bridges
Lee, Jung-Whee ; Kim, Sung-Il ; Kwark, Jong-Won ; Lee, Pil-Goo ; Yoon, Tae-Yang ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 632~637
DOI : 10.5050/KSNVN.2007.17.7.632
The dynamic behavior of two steel bridges crossed by the Korean High Speed Train(KHST) has been investigated experimentally and the results are compared with the specification requirement of BRDM and other typical PSC Box bridge's responses. The investigated bridges are a 2-girder steel bridge of 1@40m span length(E-Won Bridge), 2@50m span length (Ji-Tan Bridge), and a PSC Box girder bridge of 2@40m span length (Yeon-Jae Bridge). A set of experimental tests were performed during operation of KHST, and a number of accelerometers, LVDTs and ring-type displacement transducers were utilized for measurement of three kinds of dynamic responses (acceleration, deflection, and end-rotation angle). Measured responses show that the vertical deflections and end-rotation angles of the three bridges are all satisfying the spec. requirement with large margin, but it was also found acceleration responses which are very close or exceed the limit value. Most of the excessive acceleration responses were found when the passing velocity of the KHST is close to the critical velocity (
) which causes resonance. No noticeable differences of dynamic responses due to the different materials(steel or concrete) could be found within these experimental results.
Median HRIR Customization via Principal Components Analysis
Hwang, Sung-Mok ; Park, Young-Jin ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 638~648
DOI : 10.5050/KSNVN.2007.17.7.638
A principal components analysis of the entire median HRIRs in the CIPIC HRTF database reveals that the individual HRIRs can be adequately reconstructed by a linear combination of several orthonormal basis functions. The basis functions represent the inter-individual and inter-elevation variations in median HRIRs. There exist elevation-dependent tendencies in the weights of basis functions, and the basis functions can be ordered according to the magnitude of standard deviation of the weights at each elevation. We propose a HRIR customization method via tuning of the weights of 3 dominant basis functions corresponding to the 3 largest standard deviations at each elevation. Subjective listening test results show that both front-back reversal and vertical perception can be improved with the customized HRIRs.
Experimental Investigation on the Energy Dissipation of Friction-type Reinforcing Members Installed in a Transmission Tower for Wind Response Reduction
Park, Ji-Hun ; Moon, Byoung-Wook ; Lee, Sung-Kyung ; Min, Kyung-Won ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 649~661
DOI : 10.5050/KSNVN.2007.17.7.649
Friction-type reinforcing members(FRM) to enhance the resistance to wind loads of a transmission tower through both stiffness strengthening and damping increase are energy dissipation devices that utilize bending deflection of a tower leg. In this paper, the hysteretic behavior of the transmission tower structure with FRMs was experimentally investigated through cyclic loading tests on a half scale substructure model. Firstly, the variation of friction forces and durability of the FRM depending on the type of friction-inducing materials used in the FRM were examined by performing the cyclic loading tests on the FRM. Secondly, cyclic loading tests of a half-scale two-dimensional substructure model of a transmission tower with FRMs were conducted. Test results show that the FRM, of which desired maximum friction force is easily regulated by adjusting the amplitude of the torque applied to the bolts, have stable hysteretic behaviors and it is found that there exists the optimum torque depending on a design load by investigating the amount of energy dissipation of the FRMs according to the increase of torque.
Active Control of Structures Using Lattice Probabilistic Neural Network
Kim, Dong-Hyawn ; Chang, Seong-Kyu ; Kwon, Soon-Duck ; Kim, Doo-Kie ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 7, 2007, Pages 662~667
DOI : 10.5050/KSNVN.2007.17.7.662
A new neuro-control scheme for active control of structures is proposed. It utilizes lattice pattern of state vector as training data of probabilistic neural network(PNN). Therefore. it is the so-called lattice probabilistic neural network(LPNN). PNN makes control forces by using all the training patterns. Therefore, it takes much time to obtain a control force in application. This inevitably may delay the control action. However. control force of LPNN is calculated by using only the adjacent information of LPNN input. So, the response of LPNN is greatly faster than PNN. The proposed control algorithm is applied for three story building under California and El Centro earthquakes. Also, control results of the LPNN are compared with those of the conventional PNN. The structural responses have been suppressed effectively by the proposed algorithm.