• Title/Summary/Keyword: Peak vibration value

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Investigation for the Characters of Human Perception Level according to Acceleration Value Parameters (가속도 크기 변수에 따른 수직진동에 대한 인지수준 고찰)

  • Lee, MinJung;Han, SangWhan
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.24 no.9
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    • pp.731-740
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    • 2014
  • Occupants induced floor vertical vibrations may cause other occupant's annoyance and lead to social loss. To help control such floor vibrations, several criteria have been developed mostly based on human perception tests and floor vibration tests. Floor vibration is evaluated by comparison with criteria and vibration parameters of subject floor, such as frequency, damping ratio, acceleration value, vibration duration time and occurrence frequency. Three acceleration value parameters are used in criteria; peak acceleration, rms acceleration and VDV, when a floor vibration serviceability is evaluated. Meanwhile rms acceleration and peak acceleration are adopted as vibration limit value in criteria and researches of human perception for vibration. Occupants induced floor vibration is transient rather than steady state. However, rms acceleration is not reliable parameter for evaluating transient vibration. The objective of this study is to investigate the characters of human perception level according to acceleration value parameters for vibration induced by heel impacts and walking activities.

Analysis on the Vibration Characteristics of High Speed Train according to Track Structure (궤도구조에 따른 고속철도차량의 진동특성 분석)

  • Hur, Hyun-Moo;Park, Joon-Hyuk;You, Won-Hee
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.6
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    • pp.593-599
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    • 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.

Soil vibration induced by railway traffic around a pile under the inclined bedrock condition

  • Ding, Xuanming;Qu, Liming;Yang, Jinchuan;Wang, Chenglong
    • Geomechanics and Engineering
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    • v.24 no.2
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    • pp.143-156
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    • 2021
  • Rail transit lines usually pass through many complicated topographies in mountain areas. The influence of inclined bedrock on the train-induced soil vibration response was investigated. Model tests were conducted to comparatively analyze the vibration attenuation under inclined bedrock and horizontal bedrock conditions. A three-dimension numerical model was built to make parameter analysis. The results show that under the horizontal bedrock condition, the peak velocity in different directions was almost the same, while it obviously changed under the inclined bedrock condition. Further, the peak velocity under inclined bedrock condition had a larger value. The peak velocity first increased and then decreased with depth, and the trend of the curve of vibration attenuation with depth presented as a quadratic parabola. The terrain conditions had a significant influence on the vibration responses, and the inclined soil surface mainly affected the shallow soil. The influence of the dip angle of bedrock on the peak velocity and vibration attenuation was related to the directions of the ground surface. As the soil thickness increased, the peak velocity decreased, and as it reached 173% of the embedded pile length, the influence of the inclined bedrock could be neglected.

Development of Frequency Weighting Shape for Evaluation of Discomfort due to Vertical Whole-body Shock Vibration (수직방향 전신 충격진동의 불편함 평가를 위한 주파수가중곡선 개발)

  • Ahn, Se-Jin;Jeong, Weui-Bong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.6 s.111
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    • pp.658-664
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    • 2006
  • Shock vibrations are usually experienced in vehicles excited by impulsive input, such as bumps. The frequency weighting functions of the current standards in ISO 2631 and BS 6841 are to help objectively predict the amount of discomfort of stationary vibration. This experimental study was designed to develop frequency weighting shape for shock vibration having various fundamental frequencies from 0.5 to 16Hz. The specks were produced from the response of single. degree-of-freedom model to a half-sine force input. Fifteen subjects used the magnitude estimation method to judge the discomfort of vertical shock vibration generated on the rigid seat mounted on the simulator. The magnitudes of the shocks, expressed in terms of both peak-to-peak value and un-weighted vibration dose values (VDVs) , were correlated with magnitude estimates of the discomfort. The frequency weighting shapes from the correlation were developed and investigated having nonlinearity due to the magnitude of the shock.

An Analysis on the Influence of Wheel Flange Wear on the Vibration of EMU (전동차 차륜답면 마모에 따른 차량 진동 특성 영향 분석)

  • Hur, Hyun-Moo;Park, Joon-Hyuk;You, Won-Hee;Park, Tae-Won;Yang, Chil-Sig
    • Journal of the Korean Society for Railway
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    • v.12 no.2
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    • pp.230-235
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    • 2009
  • We have conducted an experimental study to analyze characteristics of the wheel profile wear and an influence of the wheel flange wear on the vehicle's vibration characteristics. In experiment with EMU, wheel profile wear is severe at the beginning of the commercial operation. In this stage, the variations of the wheel dimension parameters and equivalent conicity is changed rapidly. Along with a mileage of the test vehicle, the wear of the wheel flange is increased and also the vibration level of the car-body is increased. The peak-peak mean value of the body vibration is estimated as good level, but the level is approached at the limit of the good level as mileage increases. Especially, the peak-peak maximum value of the body vibration shows the distinct increase of vibration level.

The immediate effects of local vibration on ankle plantar flexor muscle activation and peak torque in healthy adults

  • Cho, Minjo;Yoon, Doyoo;Yoo, Jaehyun;Yi, Donghyun;Kang, Daewon;Yim, Jongeun
    • Physical Therapy Rehabilitation Science
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    • v.9 no.2
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    • pp.113-119
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    • 2020
  • Objective: The vibration device is one of the most commonly used warm-up devices not only for healthy athletes but also for healthy individuals. Therefore, this study aimed to investigate the immediate effects of local vibration on ankle plantar flexor muscle activation and peak torque in healthy adults. Design: One-group pretest-posttest design. Methods: This was a single-group study comprising a total of 36 (16 males and 20 females) participants. The average age of the 36 participants was 22.3 years. All the participants' concentric and eccentric peak torques of the gastrocnemius lateralis muscle were measured using an isokinetic device. Simultaneously, the participants' muscle activity was measured by surface electromyography. After the pre-experimental data were collected, the participants comfortably sat on the prepared chair with their hips and knees flexed to 90°. While in sitting position, local vibration was applied for 10 minutes using a 1:1 ratio intermittent pulsing mode device based on a previous study. Then, the post-experimental data were collected immediately after the local vibration by performing a similar process performed during the pre-experimental data collection. Results: The results showed a significant difference in muscle activity and eccentric peak torque (p<0.05). On the contrary, concentric peak torque values showed an insignificant difference with pre- and post-value. Conclusions: The results of this study demonstrated that local vibration can be possibly considered as one of the effective ways to increase ankle plantar flexor muscle activity and muscle performance, specifically the eccentric peak torque, in healthy adults.

STUDY OF SUBJECTIVE COMFORT ON SHOCK-TYPE VERTICAL WHOLE-BODY VIBRATION (쇽타입 수직방향 전신진동에 대한 주관적 안락감에 관한 연구)

  • Ahn, Se-Jin;Griffin, M.J.;Jeong, Weui-Bong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.1260-1264
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    • 2006
  • Shock-type vibrations are usually experienced in vehicles excited by impulsive forces. Fifteen subjects used magnitude estimation to judge the discomfort of vertical shock-type vibration generated on a rigid seat. The shocks had different frequencies and magnitudes and were produced from the response of a 1 degree-of-freedom model to a half-sine force input. The magnitudes of the shocks, expressed in terms of both peak-to-peak value and un-weighted vibration dose values, VDVs, were correlated with magnitude estimates of the discomfort. In this study, equivalent comfort contour of shock-type vibration were obtained. From the contour, it was investigated that shock-type vibration at frequency below 0.8 Hz and between 4.0 Hz and 10.0 Hz is highly sensitive to the discomfort than at other frequencies.

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A safety evaluation on the loading and vibration test for transport freight car of cold rolled coil sheet (냉연코일강판 수송용 화차의 안전성 평가를 위한 차체하중시험과 진동시험)

  • 김원경;정종덕;윤성철;홍용기
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1499-1502
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    • 2003
  • This paper describes the result of carbody and vibration test for freight car. The purpose of the test is to evaluate an safety which carbody structure shall be considered fully sufficient rigidity so as to load a freight car under maximum load and operating condition on line track. The test carbody is constructed by RS korea co., LTD. in accordance with KNR specfication. The test cases of the carbody is tested the vertical load and compressive load to verify the strength and stillness. The vibration test is tested for analysis and evaluation of vibration, to allow for the fact that mechanical vibration in railway vehicles have specific characteristics.

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An Acquisition and Analysis Equipment of Dynamic/Static Data on a Rotating Vibration (회전체 진동 데이터의 AC/DC 성분 데이터 획득 및 분석 장치)

  • Lee, Jung Suk;Ryu, Deung Ryeol;Lee, Cheol
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.5 no.4
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    • pp.127-137
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    • 2009
  • This paper is proposed that in-output Digital module is acquired a vibration signal of a rotating machinery by Data Acquisition System. The module is designed to get ride of nose through low pass filter on the vibration signal from sensors and set the gain value for being able to sampling AC to DC, and also the sampled data by sampler and the conversed data by DIP/FPGA is supplied to the analyzer for analysis at a software tool. The DIP(Digital Signal Processor) of the Digital input/output Board makes Average voltage, Peak to Peak voltage, RMS(Root Mean Square) and Gap voltage, also FFT(Fast Fourier Transform) for rotating vibration diagnosis.

Impulsive sound localization using crest factor of the time-domain beamformer output (빔형성기 출력의 파고율을 이용한 충격음의 방향 추정)

  • Seo, Dae-Hoon;Choi, Jung-Woo;Kim, Yang-Hann
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.713-717
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    • 2014
  • This paper presents a beamforming technique for locating impulsive sound source. The conventional frequency-domain beamformer is advantageous for localizing noise sources for a certain frequency band of concern, but the existence of many frequency components in the wide-band spectrum of impulsive noise makes the beamforming image less clear. In contrast to a frequency-domain beamformer, it has been reported that a time-domain beamformer can be better suited for transient signals. Although both frequency- and time-domain beamformers produce the same result for the beamforming power, which is defined as the RMS value of its output, we can use alternative directional estimators such as the peak value and crest factor to enhance the performance of a time-domain beamformer. In this study, the performance of three different directional estimators, the peak, crest factor and RMS output values, are investigated and compared with the incoherent interfering noise embedded in multiple microphone signals. The proposed formula is verified via experiments in an anechoic chamber using a uniformly spaced linear array. The results show that the peak estimation of beamformer output determines the location with better spatial resolution and a lower side lobe level than crest factor and RMS estimation in noise free condition, but it is possible to accurately estimate the direction of the impulsive sound source using crest factor estimation in noisy environment with stationary interfering noise.

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