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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 14, Issue 12 - Dec 2004
Volume 14, Issue 11 - Nov 2004
Volume 14, Issue 10 - Oct 2004
Volume 14, Issue 8 - Aug 2004
Volume 14, Issue 7 - Jul 2004
Volume 14, Issue 6 - Jun 2004
Volume 14, Issue 5 - May 2004
Volume 14, Issue 4 - Apr 2004
Volume 14, Issue 9 - Mar 2004
Volume 14, Issue 3 - Mar 2004
Volume 14, Issue 2 - Feb 2004
Volume 14, Issue 1 - Jan 2004
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Vibration Analysis for a Coupled MEMS-Gyroscope Design
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 655~660
DOI : 10.5050/KSNVN.2004.14.8.655
Vibration analysis for a coupled MEMS gyroscope design is presented in this paper. Slight mistuning in fabricated MEMS gyroscopes often leads to significant difference of vibration characteristics between expected and real designs. This difference frequently results in a negative effect to the MEMS gyroscope performance. As long as the coupling between excited and sensed motions exists, such difference inevitably occurs. In this paper, dimensionless parameters that govern the vibration characteristics of coupled MEMS gyroscope are identified and the effects of the parameters on the vibration characteristics are investigated.
Noise and Vibration Characteristics of Concrete Floor Structures Using Resilient Materials Driven by Standard Heavy Impact Source
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 661~667
DOI : 10.5050/KSNVN.2004.14.8.661
The characteristics of noise and vibration by a heavy impact source was studied. The triggering method was used for increasing the reliability and stability to measure the level of sound pressure. sound intensity and vibration acceleration. A simple finite element model and a rigid body analysis method were suggested to calculate the natural frequencies of the multi-layer floor system. The results show that the resilient materials decrease the natural frequency of the reinforced concrete slab, make a resonance with dominant driving frequency in the low frequency region, and increase the vibration and noise level. A simple finite element model and rigid body models was suggested to calculate the natural frequencies of the floor systems.
Acoustic Source Power Control and Global Noise Reduction by Selection of Distribution and Impedance of Absorptive Materials in Acoustically Small Enclosures
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 668~674
DOI : 10.5050/KSNVN.2004.14.8.668
The possibility of global noise reduction by the sound power control through selection of distribution and impedance of absorptive materials is discussed. It is necessary to investigate the relation between the global sound energy in the field and the total sound power radiated by sources. In the previous work,
the authors presented a useful design method to change boundary condition that can be useful to reduce noise in acoustically small enclosures. Changing boundary condition Is related to not only enclosure’s geometrical shape but also acoustical treatment on walls for example, attaching of impedance patches (ex: absorptive material). In many practical situations, we often meet situation to change acoustical treatment on walls. The possibility of total acoustic potential energy(globa1 noise) reduction by acoustic source power control is examined in an acoustically small cavity Using acoustic energy balance equation, the relation between global noise control performance and absorptive material’s arrangement/impedance is deduced. Numerical simulation is performed to interpret its physical meaning in terms of absorbent’s distribution and impedance.
A Development of the Algorithm to Detect the Fault of the Induction Motor Using Motor Current Signature Analysis
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 675~683
DOI : 10.5050/KSNVN.2004.14.8.675
The motor current signature provides an important source of the information for the faults diagnosis of three-phase induction motor. The theoretical principles behind the generation of unique signal characteristics, which are indicative of failure mechanisms, are Presented. The fault detection techniques that can be used to diagnose mechanical Problems, stator and rotor winding failure mechanisms, and air-gap eccentricity are described. A theoretical analysis is presented which predicts the presence of unique signature patterns in the current that are only characteristics of the fault. The predictions are verified by experimental results from a special fault Producing test rig and on-site tests in a steel company. And this study have made new diagnostic algorithm for the operating induction motors with the test results. These developments are including the use of monitoring and analysis of electric current to diagnose mechanical and electrical problems and gave the precise test results automatically.
A Study on the Identifying Dynamic Characteristic Parameters of Rotor-bearing Systems Using Field Measurement Data of Unbalance Responses
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 684~694
DOI : 10.5050/KSNVN.2004.14.8.684
Presented in this dissertation is a new method of identifying the critical speed of rotor-bearing systems without actually reaching at the critical speed itself. Using the method, it is possible to calculate the critical speed by measuring a series of rotor responses at much lower rotating speeds away from and without reaching at the critical speed of the system. In the course of the procedures illustrated, not only the critical speed but also the damping ratio and the eccentricity of the system can be identified at the same time. Test rotor was tested on the Rotor Dynamics Test Facility at the Korea Institute of Machinery ＆ Materials. Korea, and the theory has been confirmed experimentally. The method can be adopted to monitor changes of the dynamic characteristics of critical rotating machinery before and after overhauls, repairs, exchanges of various parts, or to detect trends or direction of subtle changes in the dynamic characteristic parameters over a long periods of time.
Shape Optimization of HDD Head Slider for Enhancing Reliabilities
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 695~701
DOI : 10.5050/KSNVN.2004.14.8.695
This study is to suggest a Probabilistic design determining configurations of slider air bearings with the dimensional manufacturing tolerances of the ABS. The probabilistic design problem is formulated to minimize the variation in flying height from a target value while satisfying the desired probabilities keeping the pitch and roll angles within a suitable range. The proposed approach first selves the deterministic optimization problem. Then, beginning with this solution, the RBDO is continued with the probabilistic constraints affected by the random variables with a fixed standard deviation in normal distribution. The RBDO results are directly compared with the values of the initial design and the results of the deterministic optimization, respectively. The reliability analyses are performed by the descriptive sampling (DS) to show the effectiveness and accuracy of the proposed approach. It is demonstrated that the Proposed RBDO approach can efficiently obtain an optimum solution satisfying all the desired probabilistic constraints.
Analysis of the Friction Induced Instability of Disc Brake Using Distributed Parameter Model
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 702~708
DOI : 10.5050/KSNVN.2004.14.8.702
This paper deals with friction-induced vibration of disc brake system under constant friction coefficient. A linear, lumped and distributed parameter model to represent the floating caliper disc brake system is proposed. The complex eigenvalues are used to investigate the dynamic stability and in order to verify simulations which are based on the theoretical model, the experimental modal test and the dynamometer test are performed. The comparison of experimental and theoretical results shows a good agreement and the analysis indicates that mode coupling due to friction force is responsible for disc brake squeal. And squeal type Instability is Investigated by using the parametric analysis. This indicates parameters which have influence on the propensity of brake squeal. This helped to validate the analysis model and establish confidence in the analysis results. Also they may be useful during system development or diagnostic analysis.
Optimization of Engine Excitation Forces for Vibration Control
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 709~717
DOI : 10.5050/KSNVN.2004.14.8.709
The diesel engine is often a serious excitation source in ships. Both the varying cylinder gas forces and the reciprocating and rotating mass forces associated with the crank and the connecting rod mechanism produce ample possibilities for excitation of the engine structure itself, the shafting, the surrounding substructures as well as the hull girder. This paper presents a guide for optimization of excitation forces produced by the marine propulsion 2-stroke diesel engine. The computational program for predicting the excitation forces is developed and applied to 2-stroke in-line engines. The object function is defined as the work done by every cylinder excitation force which is related to the mode shape of the diesel engine system, especially in the torsional vibration of the shafting. As a practical application of the presented method. the crank angle of 7 cylinder 2-stroke engine is optimized to reduce torsional vibration stresses on the shafting. Compared with the regular firing angle, about 60 ％ of the 4th order torsional vibratory stress on the propeller shaft can be reduced by optimizing the crank angle irregularly. The usefulness of the presented optimization method is confirmed by the measurements.
The Effects of the Boundary Shapes on the Structural-acoustic Coupled System
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 718~725
DOI : 10.5050/KSNVN.2004.14.8.718
If a wall separates the bounded and unbounded spaces, then the wall’s role in transporting the acoustic characteristics of the two spaces is not well defined. In this paper, we attempted to see how the acoustic characteristics of two spaces are really affected by the spatial characteristics of the wall. In order to understand coupling mechanism, we choose a finite space and a semi-infinite space separated by the flexible or rigid wall and an opening. A volume interaction can be occurred in structure boundary and a pressure Interaction can be happened in the opening boundary. For its simplicity, without loosing generality, we use rather simplified rectangle model instead of generally shaped model. The source impedance is presented to the various types of boundaries. The distributions of pressure and active intensity are also presented at the cavity- and structure-dominated modes. The resulting modification, shifts of modal frequencies and changing of standing wave patterns to satisfy both coupled boundary conditions and governing equations, are presented.
On-line Phase Tracking of Patch Type EFPI Sensor and Fuzzy Logic Vibration Control
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 726~733
DOI : 10.5050/KSNVN.2004.14.8.726
On-line phase tracking of an extrinsic Fabry-Perot interferometer (EFPI) and experimental vibration control of a composite beam with a sensing-patch are investigated. We propose a sensing-patch for the compensation of the interferometric non-linearity. In this paper. a sensing-patch that comprises an EFPI and a piezo ceramic(PZT) is fabricated and the characteristics of the sensing-patch are experimentally investigated. A simple and practical logic is applied for the real-time tracking of optical phase of an interferometer Experimental results show that the proposed sensing-patch does not have the non-linear behavior of conventional EFPI and hysteresis of piezoelectric material. Moreover, it has good strain resolution and wide dynamic sensing range. Finally, the vibration control with the developed sensing-patch has been performed using Fuzzy logic controller, and the possibility of sensing-patch as a sensoriactuator is considered.
Use of Composite Tailoring Techniques for a Low Vibration Rotor
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 734~740
DOI : 10.5050/KSNVN.2004.14.8.734
In this work, the effect of composite couplings and mass distributions on hub loads of a hingeless rotor in forward flight is investigated. The hingeless composite rotor is idealized as a laminated thin-walled box-beam. The nonclassical effects such as transverse shear and torsion warping are considered In the structural formulation. The nonlinear differential equations of motion are obtained by applying Hamilton’s principle. The blade responses and hub loads are calculated using a finite element formulation both in space and time. The aerodynamic forces acting on the blade are calculated using the quasi-steady strip theory. The theory includes the effects of reversed flow and compressibility. The magnitude of elastic couplings obtained by MSC/NASTRAN is compared with the classical pitch-flap(
) coupling. It Is observed that the elastic couplings and mass distributions of the blade have a substantial effect on the behavior of
/rev hub loads. About 40％ hub loads is reduced by tailoring or redistributing the structural properties of the blade.e.
Buckling and Vibration Characteristics of the Capsule for Nuclear Fuel Irradiation Test
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 741~748
DOI : 10.5050/KSNVN.2004.14.8.741
The vibration and buckling characteristics of the capsule for fuel irradiation test are studied. The natural frequencies of the capsule in air and under water are obtained by modal testing and finite element (FE) analysis using ANSYS program, and accelerations with flow are measured to estimate the compatibility with the operation requirement of the HANARO reactor. The experimental fundamental frequencies of the capsule in the x and z direction are 8.5 Hz and 8.75 Hz in air, and 7.5 Hz and 7.75 Hz under water, respectively. The maximum amplitude of accelerations under the normal operating condition is measured as 11.0 m/s
that is within the allowable vibrational limit(18.99 m/s
) of the reactor structure. Also, the maximum displacement at 100％ flow is calculated as 0.13 mm which is not interference with other nearby structures. FE analysis results show that the natural frequencies are found to be similar to those of the modal testing when three supporting parts are considered as simply supported conditions. From the buckling analysis, when the loading tool is applied, the critical buckling load of the capsule is 233 N
Torsional Vibration Stress Analysis for Shafting in Reciprocating Machine by Transfer Stiffness Coefficient Method
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 749~756
DOI : 10.5050/KSNVN.2004.14.8.749
While designing shafting in reciprocating machines with internal combustion engines which derive generators, pumps, and vehicles, it is very important to calculate the additional stress of shafting by torsional vibration. In this paper, the transfer stiffness coefficient method which is based on the successive transfer of stiffness coefficient was applied to the calculation of the additional stress of shafting in reciprocating machine by torsional vibration. In order to confirm the effectiveness of the present method, a propulsion shafting with a diesel engine in a vessel was considered as the computational example of shafting in reciprocating machine. The results calculated by the present method were compared with those of the modal analysis method, the mechanical impedance method, and free vibration analysis.
Optimal Placement of Strain Gauge for Vibration Measurement : Formulation and Assessment
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 757~766
DOI : 10.5050/KSNVN.2004.14.8.757
This paper focuses on the formulation and validation of an automatic strategy to select the optimal location and direction of strain gauges for the measurement of the modal response. These locations and directions are important to render the strain measurements as robust as possible when a random mispositioning of the gauges and gauge failures are expected. The approach relies on the evaluation of the signal-to-noise ratios of the gauge measurements from strain data of finite element. The multi-step optimization strategy including genetic algorithm is used to find the strain gauge locations-directions that maximize the smallest modal strain signal-to-noise ratio in the absence of gauge failure or its expected value when gauge failure is possible. A flat Plate is used to prove the applicability of the proposed methodology and to demonstrate the effects of the essential parameters of the problem such as the mispositioning level, the probability of gauge failure, and the number of gauges.
An Experimental Study on a Magneto-Rheological Fluid Damper for Structural Control Subject to Base Excitation
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 8, 2004, Pages 767~773
DOI : 10.5050/KSNVN.2004.14.8.767
Semi-active control systems have attracted a great deal of attention in recent years, because they offer the adaptability of active devices without requiring large Power sources. One of the most Promising semi-active devices proposed for structural control is magneto-rheological fluid dampers (MR damper). In this paper, an MR damper having the capacity of about 1 ton was designed and fabricated. and series of tests were performed to grasp the fundamental Performance characteristics of it. It was also applied to a 6-story steel structure under random excitation and 3-different seismic excitations for the confirmation of its validity on structural vibration absorption. Through this study, the techniques and know-hows for MR damper production were acquired.