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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 16, Issue 12 - Dec 2006
Volume 16, Issue 11 - Nov 2006
Volume 16, Issue 10 - Oct 2006
Volume 16, Issue 9 - Sep 2006
Volume 16, Issue 8 - Aug 2006
Volume 16, Issue 7 - Jul 2006
Volume 16, Issue 6 - Jun 2006
Volume 16, Issue 5 - May 2006
Volume 16, Issue 4 - Apr 2006
Volume 16, Issue 3 - Mar 2006
Volume 16, Issue 2 - Feb 2006
Volume 16, Issue 1 - Jan 2006
Selecting the target year
Noise Reduction of PDP TV Cooling Fan System through Parameter Analysis
Kim, Kyu-Young ; Choi, Min-Goo ; Lee, Duck-Joo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 107~114
DOI : 10.5050/KSNVN.2006.16.2.107
The present experimental study deals with noise reduction and improvements in cooling performance in a plasma display panel (PDP) television (TV). The main ideas of the fan system noise reduction are maintenance of uniform inflow condition and reduction of the system loss,
The discrete noise is mainly related with the inflow condition therefore removing the structure which distorts inflow makes the discrete noise reduction. The broadband noise in PDP TV is related with the system losses which result from the presence of the fan downstream obstacle, PDP rear case. Through the modification of the distance and preventing the leakage flow between the fan and rear case, we can obtain the system loss and broadband noise reduction. Additionally we can reduce fan rotating speed because of increased flow rate which obtains from the reduction of system loss (resistance). Finally, 4.2 dB(A) noise reduction and
increase in flow rate are achieved. From these results, we show that the reduction of system loss is the most effective way of the fan system noise reduction.
A Feasibility Study on the Application of the Topology Optimization Method for Structural Damage Identification
Lee, Joong-Seok ; Kim, Jae-Eun ; Kim, Yoon-Young ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 115~123
DOI : 10.5050/KSNVN.2006.16.2.115
A feasibility of using the topology optimization method for structural damage identification is investigated for the first time. The frequency response functions (FRFs) are assumed to be constructed by the finite element models of damaged and undamaged structures. In addition to commonly used resonances, antiresonances are employed as the damage identifying modal parameters. For the topology optimization formulation, the modal parameters of the undamaged structure are made to approach those of the damaged structure by means of the constraint equations, while the objective function is an explicit penalty function requiring clear black-and-white images. The developed formulation is especially suitable for damage identification problems dealing with many modal parameters. Although relatively simple numerical problems were considered in this investigation, the possibility of using the topology optimization method for structural damage identification is suggested through this research.
Noise Test and Evaluation of a 750 kW Wind Turbine Generator
Kim, Seock-Hyun ; Kim, Tae-Hyung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 124~131
DOI : 10.5050/KSNVN.2006.16.2.124
This study introduces an environmental noise evaluation procedure for wind turbines(W/T) and the evaluation result of a 750 kW wind turbine(W/T) system. Test and evaluation are performed according to the international standard IEC 61400-11 on J48 W/T which is under operation in Daekwanryung W/T test site. With the meteorological data and W/T operational data, noise data are monitored and analysed. An integrated monitoring system is constructed in the test site and is utilized for the evaluation. From the measured noise data, acoustic power level, directivity and tonality of the W/T are estimated under the wind speeds required fly the International standard. The purpose of the study is to establish an W/T noise evaluating system satisfying the international standard and to obtain noise data for home made 750 kW W/T.
Dynamic Response Characteristics of Floating Structures According to Connection Types
Kim, Byoung-Wan ; Hong, Sa-Young ; Kyoung, Jo-Hyun ; Cho, Seok-Kyu ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 132~140
DOI : 10.5050/KSNVN.2006.16.2.132
This paper investigates the characteristics of dynamic responses of floating structures with connections under sea wave loads. Direct method using higher order boundary element method (HOBEM) and finite element method (FEM) is adopted for numerical analysis. A 500 m-long and 250-m width very large floating structure (VLFS) with four units are considered in numerical analysis. Hinge connection and spring connection with various strength are considered as connection types. Displacements and stresses of VLFS according to the connection types are compared considering wave period and heading angle reduction.
An Experimental Study on the Sound Insulation Performance of Korean Traditional Houses
Kim, Sun-Woo ; Lee, Tai-Gang ; Kim, Hyung-Ryul ; Kim, Hang ; Choi, Eun-Suk ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 141~148
DOI : 10.5050/KSNVN.2006.16.2.141
Korean traditional houses have been evolved and developed in many years, adopting the natural environment to control exterior conditions. These control method are various Passive system of using natural materials, considering micro climate, building lay out, and these system are much natural and ecological to make the comfortable indoor climate than active systems of the present houses. This study aims to analyzed the acoustical characteristics of Korean traditional houses varied with lay out and floor plan to reflect the way of control for environmental condition. The reverberation time and level difference between rooms of the main living room and other main floored room, master room and kitchen are measured in each houses. As a result, the reverberation time of Korean traditional rooms are below 0.6 second, and the sound insulation performance of Korean traditional door are mostly very low grade with D-15. The level difference between rooms are low grade not to meet minimum class except between main living room and master room away from main living building. These above results show that our traditional house are much more emphasized seeking visual privacy of rooms than aural privacy.
A Study on the Evaluation Factors for Diffuser Noise of HVAC
Park, Hyeon-Ku ; Kim, Hang ; Kim, Sun-Woo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 149~155
DOI : 10.5050/KSNVN.2006.16.2.149
There are various types of noise around us such as road traffic noise, aircraft noise and floor impact sound, equipment noise, etc. Researches on the noise criteria and the evaluation method for the diffuser noise of HVAC are insufficient. dB(A) and NC values represented in ASHRAE guide book are applied as a noise criteria for diffuser noise, which have some problems like that the values between dB(A) and NC have deviation even if the sound is same one. Therefore, the evaluation method should be considered and proposed based on the subjective responses. From these reasons, this study aimed to analyze the evaluation factors for the diffuser noise of HVAC reflected on the subjective responses by surveying vocabularies and grouping them with factor analysis.
Suggestion of Prediction Equation for Environmental Noise of Saemaeul Train
Cho, Jun-Ho ; Koh, Hyo-In ; Kim, Jae-Chul ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 156~162
DOI : 10.5050/KSNVN.2006.16.2.156
For the reduction and efficient management of railway noise, first of all prediction of railway noise is necessarily requisited. Many studies for prediction of railway nearby noise have been accomplished. But it is impossible to predict easily and exactly for the Korean Railway, because the acoustic powers for each rolling stock operated in Korea have not been built yet. So in this study, Prediction model equation for environmental noise for Korean rolling stock Saemaeul was suggested using SEL of engine and rolling noise component separately. Finally for the validation of prediction equation, the predicted result was compared to the measured.
Experimental Study on the Damping Estimation of the 5×5 Partial Fuel Assembly
Lee, Kang-Hee ; Yoon, Kyung-Ho ; Song, Kee-Nam ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 163~168
DOI : 10.5050/KSNVN.2006.16.2.163
The PWR Nuclear Fuel assembly consists of more than 250 fuel rods that are supported by leaf springs in the cells of more than 10 Spacer Grids (SG) along the rod length. Since it is not easy to conduct mechanical tests on a full-scale model basis, the small-scaled rod bundle
which is called partial fuel assembly is generally used for various performance tests during the development stage. As one of the small-scaled tests, a flow test should be carried out in order to verify the performance of the spacer grid to obtain the Flow-Induced Vibration (FIV) characteristics of the scaled fuel assembly over the specified flow range. A vibration test should be also performed to obtain the modal parameters of the assembly prior to the flow test. In this study, we want to develop the estimation procedure of the damping ratio for the scaled test assembly. For the damping factor of the partial fuel assembly and the grid cage at the first vibration mode, as one of the vibration tests, a so-called pluck testing has been performed in air as a preliminary test prior to in-flow damping measurement test. Logarithmic decrement method is used for calculation of the damping ratio. Estimated damping ratio of the partial fuel assembly is about
with reasonable error of
for the previous results. Nonlinear behavior of the partial fuel assembly might be stem mainly from the rod-grid support configuration.
Vibration Analysis and Critical Speeds of Rotating Polar Orthotropic Disks, Part I : Formulation and Solution Method
Koo, Kyo-Nam ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 169~175
DOI : 10.5050/KSNVN.2006.16.2.169
Rotating annular disks are widely used in data storage devices such as CDs, DVDs(digital versatile disks), and HDs(hard disks). Higher data transfer rate in data storage disks could not be achieved by polycarbonate disks in the present market. The problem can be solved by applying the fiber-reinforce composite materials to the disks. In this paper, an application of composite materials to rotating disks is proposed to increase the critical speed. Dynamic equation is formulated in order to calculate the natural frequency and critical speed for rotating composite disks by the Galerkin method. The orthogonal functions are used in series solution. A companion paper(Part II) presents and discusses the numerical results of vibration analysis and critical speed for rotating polar orthotropic disk using the formulation and solution method given in this paper (Part I).
Modeling and Verification for Stability Analysis of Axially Oscillating Cantilever Beams
Kim, Sung-Do ; Yoo, Hong-Hee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 176~182
DOI : 10.5050/KSNVN.2006.16.2.176
Modeling and verification for stability analysis of axially oscillating cantilever beams are investigated in this paper Equations of motion for the axially oscillating beams are derived and transformed into dimensionless forms. The equations include harmonically oscillating parameters which are related to the motion-induced stiffness variation. stability diagram is obtained by using the multiple scale perturbation method. To verify the accuracy of the modeling method, several points in the plane of the stability diagram are presented and solved. The present modeling method proves to be as accurate as a nonlinear finite element modeling method.
Development of Combined Permanent Magnet Type Microspeakers Used for Mobile Phones
Hwang, Sang-Moon ; Lee, Hong-Joo ; Kwon, Joong-Hak ; Hwang, Gun-Yong ; Yang, Yong-Chang ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 183~189
DOI : 10.5050/KSNVN.2006.16.2.183
In mobile phones of multimedia era, microspeakers of high qualify sound are essential parts to generate human voice in speaker phone and MP3 song player. In this paper, two types of microspeakers, outer permanent magnet (PM) and combined PM type, are analyzed using electromagnetic, mechanical and their coupling analysis. For performance comparison, voice coil diameter is chosen as a design parameter to change excitation position and magnet volume for both types. For combined PM type, sound pressure level (SPL) is improved due to increased PM volume compared to outer PM type. Also, with the decreased voice coil diameter for combined PM type, the 1st resonant mode of the diaphragm is more efficiently excited due to concentrative excitation, resulting in lower and broader frequency range. Therefore, it can be said that the combined PM type microspeakers are more advantageous for high performance microspeaker which are essential for multimedia era.
Investigation on Shapes and Acoustic Characteristics of Air Bubbles Generated by an Underwater Nozzle
Kim, Jong-Chul ; Oh, Joon-Seok ; Cho, Dae-Seung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 190~197
DOI : 10.5050/KSNVN.2006.16.2.190
It is well known that the acoustic characteristics of the sea are significantly affected by bubbles which have their own inherent characteristics at the undersea. In this study, the shape and acoustic characteristics of air bubbles generated by an underwater nozzle are calculated numerically, and are measured with a high speed camera and a hydrophone at various air flow rates in the experimental apparatus. As a result of analysis, the shape calculated numerically well matched with measured values at low flow rates, but in case of relatively higher flow rates. the use of correction coefficient is needed for more accurate estimation of the bubble shape. And also the rising velocity of a single bubble is constant regardless of both the bubble size and the flow rate. and the acoustic signal generated when the bubble is produced by an underwater nozzle has the same characteristic of natural frequency of the bubble pulsation, and is agreed with Minnaert`s equation if the correction coefficient is considered in accordance with the flow rate.
Out-of-plane Vibration for an Axially Moving Membrane
Shin, Chang-Ho ; Chung, Jin-Tai ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 198~206
DOI : 10.5050/KSNVN.2006.16.2.198
The dynamic responses of both the in-plane and out-of-plane vibrations are investigated for an axially moving membrane. The equations of motion are derived for the moving membrane with no-slip boundary conditions by using the extended Hamilton principle. Based on the Galerkin method, the discretized equations of motion are derived. The generalized-time integration method is applied to compute the dynamic responses for the in-plane and out-of-plane motions. From the computed results, the responses are compared between the in-plane and out-of-plane vibrations. Furthermore. the effects of velocity and acceleration on the dynamic behaviours for displacements and stresses are presented.
Experimental Study on Stability of Robust Saturation Controller
Lim, Chae-Wook ; Moon, Seok-Jun ; Park, Youngjin ; Park, Yun-Sik ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 2, 2006, Pages 207~213
DOI : 10.5050/KSNVN.2006.16.2.207
In our previous research, we proposed a robust saturation controller which involves both control input saturation and structured real parameter uncertainties. This controller can analytically prescribed the upper and lower bounds of parameter uncertainties, and guarantee the closed-loop robust stability of the system in the presence of actuator`s saturation. And the availability and the effectiveness of the proposed robust saturation controller were verified through numerical simulations. In this paper, we verify the robust stability of this controller through experimental tests. Expecially, we show unstable cases of other controllers in comparison with this controller. Experimental tests are carried out in the laboratory using a two-story test structure with a hydraulic-type active mass damper.