• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.1-5
• /
• 2007

A majority of piping vibration problems are induced by internal fluid pulsation; turbulent flow, vortex shedding at internal discontinuities, and pressure pulsation at equipment nozzles. The pulsation at the pressure sources resonates acoustically with the piping and the amplified pressure pulsation can generate shell mode vibration in the piping. Reheater attemperator piping supplies water from feedwater pump to reheater attemperator to control the boiler temperature. In normal operating condition, the high frequency shell mode vibration occurred in the piping with the high level of sound(105 ${\sim}$ 117 dB). The vibration sources are pressure pulsation in the pump nozzle and the frequencies are related to the blade passing frequencies. The objects of this paper are to analyze the cause of the high frequency vibration and to establish corrective actions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.1089-1094
• /
• 2003

A main vibration source in HDD is arisen from high rotating disk/spindle, and vibration suppression of the disk-spindle system becomes a critical issue and a major concern for high performance of the drive. In this paper, we study the feasibility of suppressing unwanted vibration of disk-spindle system of the HDD by external shock and excitation utilizing piezoelectric shunt damping methodology. By considering dynamic characteristics of the disk-spindle system through modal analysis, a target vibration mode is determined and then the piezoelectric material is carefully integrated to the modified drive. In order to maximize improvement of vibration characteristics of the proposed system, shunt circuit is optimally designed via tuning processes. Finally, the vibration characteristics of the high rotating disk-spindle system of the proposed drive is experimentally evaluated in frequency domain.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.840-845
• /
• 2004

Development of the linear motors is recently required to control a high-speed and high-resolution in the high-integrated and speed process industry. This paper presents vibration analyses as well as measurement standards of the newly developed linear motors through analyzing the vibration characteristics of the advanced products. Vibration experiments are conducted for identifying vibration level during operation. They are also included in the modal test to analyze dynamic characteristics. Analytic data using Finite Element Method (FEM) are compared with the results of the modal. The FEM and experiments make it possible to understand these characteristics. Further, through computer simulation for the behavior of moving part to be vibration source, the best acceleration pattern of moving part movement can be verified to achieve effective moving part positioning and reduce the vibration due to moving part movement.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.6
• /
• pp.593-599
• /
• 2012

To analyze the effect of the track structure on the running performance of the railway vehicle, we studied on the vibration and ride characteristics of the high speed train. As results, vibration and ride level of high speed train on the concrete bed track is more reduced than on the ballast bed track. Peak-peak value of carbody vibration on the concrete bed track at 300km/h is half of the peak-peak value of carbody vibration on the ballast bed track. Ride level on the concrete bed track at 300km/h is same level as that on the ballast bed track at 250km/h. Thus, Vibration and ride performance of the high speed train on the concrete bed track is greatly improved compared with that on the ballast bed track.

• Proceedings of the KIEE Conference
• /
• 2008.05a
• /
• pp.189-190
• /
• 2008

This study was investigated a possibility of fault of glass insulator due to vibration on high-speed railway. The proper vibration of 1-glass insulator have many frequency band and high amplitude showed in high frequency than low frequency. The proper vibration of strut tube insulator was lowest 170Hz, highest 1.5kHz. The field signal amplitude of viaduct and open route were biggest moment pantograph of high-speed rail. The surface vibration(V3) amplitude of strut tube insulator was biggest. From the FFT analysis of viaduct and open route, the strut tube insulator effect by vertical vibration was big, the frequency was 82.5Hz and 105Hz, respectively. However, in comparison with the proper vibration of strut tube insulator, the resonance was not observed. Although the amplitude of insulator is high, the possibility of fault is low because the glass insulator deterioration by the accumulation of vibration do not happen.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.1435-1440
• /
• 2008

High-speed train under development is a type of EMU(electric multiple units). Since power sources like motors and gears are distributed in the high-speed EMU, the high-speed EMU generates vibration and sound more than the articulated high-speed train. Vibration of vehicle, vibration between rails and wheels, hunting of bogie and snake motion reduce ride comfort. In this paper, to decrease the vibration of the articulated high-speed train, improvements were presented using an analytical model and a simulation model. The simulation model of the high-speed EMU was designed on the basis of the korean high-speed train and the design parameters for ride comfort were showed and the dynamic characteristics of the vehicle was understood. To consider the characteristics of the vehicle suspension, the analytical model was designed and the simulation model was verified with it.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2010.10a
• /
• pp.380-384
• /
• 2010

A disturbance flow at piping bands and discontinuous regions such as a valve, a header has a intense broadband internal pressure field and a sound field which are propagated through the piping system The fields becomes the source of a vibration of this piping system. Intense broadband disturbance flow at a discontinuous region such as elbows, valves or headers generates an acoustical pulsation. The pulsation becomes the source of structural vibration at the piping system. If it coincides with the natural frequency of the pipe system, excessive vibration results. High-level vibration due to the pressure pulsation affects the reliability of the plant piping system. This paper discusses the high vibration and the branch vent pipe's failure of condensate-water supply piping system due to the effect of acoustical pulsations by flow turbulence from the flow control valves of globe type in a power site.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1996.10a
• /
• pp.377-385
• /
• 1996

In the case of a precision equipment, it requires a vibration free environment to provide its proper function. Especially, lithography and inspection devices, which have sub-nanometer class high accuracy and resolution, have come to necessity for producing more improved giga class semiconductor wafers. This high technology equipments require very strict environmental vibration standard in proportion to the accuracy of the manufacturing, inspecting devices. The vibration criteria are usually obtained either by the real vibration exciting test on the equipment or by the analytical calculation. the former is accurate but requires a great deal of time and efforts while the latter lacks reliability. this paper proposes a new method to solve this problem at a time. the permissible vibration level to a precision equipment can be easily obtained by analyzing a process of Frequency Response Function. This paper also demonstrates its effectiveness by applying the proposed method to finding the vibration criteria of a Computer Hard Disk Drive by impact Test.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2005.04a
• /
• pp.375-382
• /
• 2005

In this paper, a practical control method of wind-induced vibration of high-rise buildings is presented in the form of resizing algorithm. In the structural design process for high-rise buildings, the lateral load resisting system for the building is more often determined by serviceability design criteria including wind-induced vibration level. Even though many drift method have been developed in various forms, no practical design method for wind induced vibration has been developed so far. Structural engineers rely upon heuristic or experience in designing wind induced vibration. The performance of the proposed method is evaluated by comparing wind-induced vibration levels estimated both from approximate techniques and wind tunnel test.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.11a
• /
• pp.82-83
• /
• 2008

In the cases of high speed railway bridge, dynamic behavior analysis is important because of high passing velocity and moving load at the regular intervals, and the damping ratio is a major element in dynamic behavior analysis. In this paper, damping ratios were estimated by two methods and vibration type sections, and relationship between estimated damping ratio and representative value of bridge vibration. At the results, estimated damping ratio using all time of vibration were more stable then using only free vibration section. And in the case of using extended Kalman filter, estimated damping ratio were trend of growth by growth of representative value of bridge vibration. At last, it was shown that study about reliabilities of estimated damping ratios were need.