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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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Identifications and Reduction Methods of Aerodynamic Noise Sources in High Speed Rotating Optical Disk Drive
Kim, Yong-Seok ; Lee, Duck-Joo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 6, 2007, Pages 477~483
DOI : 10.5050/KSNVN.2007.17.6.477
Major noise source in high speed rotating optical disk drives (CD and DVD-ROM) arises due to the high-speed airflow produced from the upper and lower surfaces on the rotating disk. The present paper deals with the experimental approach how to identify the noise source based on the fundamental principles of aeroacoustics and to propose a reduction method of the noise source. The CD-ROM device is composed of disk, window tray, motors at the bottom place and electronic circuit plate also located below the window plate. The window is cut in the tray to read the disk information using the optical device located below the tray and moving linearly from the center of the disk through the end of the disk. All components are possible noise generators. Experimental studies were carried out in the anechoic room with various design modifications, such as tray geometry, window size and hole location on tray, to identify the major aerodynamic noise source and significant reductions of the aerodynamic noise were obtained.
Drop/Impact Simulation and Experimental Verification of a Reciprocating Compressor Body
Kim, Tae-Jong ; Kim, Moon-Saeng ; Koo, Ja-Ham ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 6, 2007, Pages 484~490
DOI : 10.5050/KSNVN.2007.17.6.484
A reciprocating compressor used in domestic refrigerators can be subjected to many different forms of shock. These shocks are usually experienced during transporting the products from a manufacturer to customers. The hermetic structure of this kind of compressor makes it difficult to conduct drop tests for identifying the failure mechanism and their drop behaviors. The drop/impact simulation for a reciprocating compressor has been carried out with the explicit code LS-DYNA and its validation has been experimentally verified. Simulation results are in good agreement with those of drop test. The present method of drop/impact simulation provides an efficient and powerful solution to improve the design quality and reduce the design period.
Efficient Method to Estimate the Number of Exposed People to Industrial Noise Using the GIS and Three Dimensional Noise Mapping - Focusing on the Industrial Noise -
Ko, Joon-Hee ; Chun, Hyung-Joon ; Chang, Seo-Il ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 6, 2007, Pages 491~497
DOI : 10.5050/KSNVN.2007.17.6.491
Reasonably accurate estimation of the exposed population to the distinct levels of noise is essential to the efficient management of urban environmental noise. This study proposes a method of calculating the number of exposed people to industrial noise by using GIS tool and noise mapping. The exposed population of noise based on estimation of the number of people that lived in each building in urban area is compared with the one based on density of population. This study suggests the five step method that consists of gathering the fundamental data, extracting the property from the digital map, noise mapping based on the three dimensional topography, estimating population that lives in each building, merging the various results with GIS tool, and estimating exposed population to industrial noise through analyzing the noise map with GIS tools.
Fluidelastic Instability of Flexible Cylinders in Tube Bundle Subjected to Cross Air-flow
Sim, Woo-Gun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 6, 2007, Pages 498~506
DOI : 10.5050/KSNVN.2007.17.6.498
Using wind tunnel, experimental approaches were employed to investigate fluidelastic instability of tube bundles, subjected to uniform cross flow. There are several flow-induced vibration excitation mechanisms, such as fluidelastic instability, periodic wake shedding resonance, turbulence-induced excitation and acoustic resonance, which could cause excessive vibration in shell-and tube heat exchanges. Fluidelastic is the most important vibration excitation mechanism for heat exchanger tube bundles subjected to cross flow. The system comprised of cantilevered flexible cylinder(s) and rigid cylinders of normal square array, In order to see the characteristics of flow in tube bundles, particle image velocimetry was used. From a practical design point of view, Fluidelastic instability may be expressed simply in terms of dimensionless flow velocity and dimensionless mass-damping. The threshold flow velocity for dynamic instability of cylinder rows is evaluated and the data for design guideline is proposed for the tube bundles of normal square array.
An Investigation of Acoustic Signal Characteristics in Turning of Aluminum
Kim, Yong-Yun ; Lee, Chang-Hee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 6, 2007, Pages 507~514
DOI : 10.5050/KSNVN.2007.17.6.507
This paper reports on the research which investigates acoustic signals acquired in turning with rough and finish simultaneously. The material is aluminum thin pipe. Two acousto-ultrasonic sensors were set on the finish and the rough bite of the CNC machine. It was first evaluated that one source was affected by the other. It was found that two signals were little affected each other, and that the acoustic signal from the finish bite was more related to the surface defects. Signals from the finish bite only were then analyzed in order to observe several types of surface defects. Second the fundamental experiments were accomplished to study the effects of machine vibration and material state. The signal characteristics due to surface defects were studied from the collected acoustic signals. The analysis was based on real time data, root mean squared average and frequency spectrum by fast fourier transform. As a result, the acoustic signals were made effects by machine condition, material structure. The acoustic signal from the finish bite was closely correlated with surface quality. Two types surface micro defects were then evaluated by the signal characteristics.
A Study on Response Analysis of 6-DOF Pneumatic Vibration Isolation Table Loaded by Transient Movements of Carriage on It
Sun, Jong-Oh ; Shin, Yun-Ho ; Kim, Kwang-Joon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 6, 2007, Pages 515~523
DOI : 10.5050/KSNVN.2007.17.6.515
As environmental vibration requirements on precision equipments get more stringent, use of pneumatic vibration isolators becomes more crucial and, hence, their dynamic performance needs to be further improved. Dynamic behavior of those pneumatic vibration Isolation tables is very important to both manufacturer and customer as performance specifications. Together with conventional transmissibility, transient response characteristics are another critical performance index especially when movements of components, e.g., x-y tables, of the precision equipments are very dynamic. In this paper, analysis on transient response of a pneumatic vibration isolation table loaded by a mass moving on it is presented. This is a conventional dynamics problem on a rigid body with 6 degree of freedom and a mass with another degree of freedom. How to obtain transient responses of the isolation table is described when the movements of the mass are prescribed relative to the table.
Friction Model to Realize Self-excited Vibration of Multi-body Systems
Roh, Hyun-Young ; Yoo, Hong-Hee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 6, 2007, Pages 524~530
DOI : 10.5050/KSNVN.2007.17.6.524
This paper presents a friction model to realize self-excited vibration of multi-body systems. The friction coefficient is modeled with a spline function in most commercial codes. Even if such a function resolves the problem of discontinuity in friction force, it cannot realize self-excited vibration phenomena. Furthermore, as the relative velocity approaches zero, the friction coefficient approaches zero with the conventional model. So, slip occurs when small force is applied to the system. To avoid these problems a new friction model is proposed in this study. With the new friction model, the self-excited vibration can be realized since the friction coefficient changes with the relative velocity. Furthermore, the slip phenomena could be reduced significantly with the proposed model.
Free Vibration Analysis of Clamped Plates with Arbitrary Shapes Using Series Functions
Kang, Sang-Wook ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 6, 2007, Pages 531~538
DOI : 10.5050/KSNVN.2007.17.6.531
A new method for free nitration analysis using series functions is proposed to obtain the eigenvalues of arbitrarily shaped, polygonal plates with clamped edges. Since a general solution used in the method satisfies the equation of motion for the transverse vibration of a plate, the method offers very accurate eigenvalues, compared to FEM or BEM results. In addition, the method can minimize the amount of numerical calculation because it has the advantage of not needing to divide the plate of interest. Two case studies show that the proposed method is valid and accurate when the eigenvalues by the proposed method are compared to those by FEM (NASTRAN) or another analytical method.
Disk Vibration and Eccentricity Compensation of Near Field Recording Systems Based on the Internal Model Principle
Jeong, Jun ; Kim, Joong-Gon ; Park, No-Cheol ; Yang, Hyun-Seok ; Park, Young-Pil ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 6, 2007, Pages 539~546
DOI : 10.5050/KSNVN.2007.17.6.539
Information storage devices using disks have a disk vibration at the frequency which is equivalent to the disk rotational speed. They also have a track vibration due to the disk eccentricity at the same frequency. In near field recording systems, the former affects the air-gap servo and the latter affects the tracking servo. In this paper, we introduce a novel control algorithm based on the internal model principle to both servos. A controller block designed by the principle is connected to the base lead-lag type compensator in parallel in order to cancel the repeatable run-out due to the disk vibration or eccentricity. Simulation and practical application of the algorithm on a near field recording system show good servo performance.
Study to Propose the Suitable Reproducing Sound Level of SAFRS
Jeon, Ji-Hyeon ; Shin, Yong-Gyu ; Kook, Chan ; Jang, Gil-Soo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 6, 2007, Pages 547~552
DOI : 10.5050/KSNVN.2007.17.6.547
SAFRS(spontaneous acoustic field reproduction system) is a system to sense changes of surroundings and produce sounds which can go well with environment elements sensed by the system in to the space. The sounds were judged by individual evaluation and, the classification of the preferred sounds according to the mood of the space was suggested in the former study. Effectiveness of SAFRS with field application was validated by prior studies which dealt with researching acoustic environment, evaluating images of sounds, and rating environment with existence and nonexistence of sound resources such as fountains and the system after applied in D university. In this study, for more effective field application of SAFRS, research for the acoustic environment around sound resources and subjective evaluation of the preference of the sounds from the resources were made and it was considered that the results of the experiments should be primary information to propose proper sound level to be offered by the system. The results of the study are as follows; 1) It was considered that the ambience of the center road was dependent upon produced sounds by the system and water sounds of the fountain and that of walk way was mostly dependent upon produced sounds. 2) The results of the subjective evaluation showed that the distance from sound resources was suggestive; the more distant from produced sounds the less full and clear the sounds, the less distant from the sounds of water the more delight and idyllic ambience, and the less distant from the forest the more idyllic ambient and diversity. 3) The results upwards were telling that an average value of six elements for the evaluation was even at the place set back 10.2m from center road and walk way. And harmony of all sounds of the place should be considered to propose suitable sound level of SAFRS.
Optimal Design of Tuned Mass Damper Considering the Friction between the Moving Mass and the Rail
Lee, Sang-Hyun ; Woo, Sung-Sik ; Cho, Seung-Ho ; Chung, Lan ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 6, 2007, Pages 553~559
DOI : 10.5050/KSNVN.2007.17.6.553
In this study, based on the results from the sinusoidal base excitation analyses of a single degree of freedom system with a tuned mass damper (TMD), it is verified that optimal friction force can improve the performance of a TMD like a linear viscous damper which has been usually used in general TMD. The magnitude of the optimal friction increases with increasing mass ratio of the TMD and decreases with increasing structural damping. Particularly, it is observed that the optimized friction force gives better control performance than the optimized viscous damping of the TMD. However, because the performance of the TMD considerably deteriorates when the friction force increases over the optimal value, it is required to keep the friction force from exceeding the optimal value.