• Title/Summary/Keyword: Vibration body

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Effects of whole-body vibration on human performance (전신진동이 인간성능에 미치는 영향)

  • 이남식;박세진;김철중
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1990.10a
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    • pp.91-98
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    • 1990
  • This paper reviews the previous researches related to the effects of whole-body vibration on human performance. The physiological effects of vibration were reviewed in the first part, and the effects of vibration on vision and manual control performance were discussed. the relationships between vibration and ride quality were also discussed. ISO-2631 was briefly reviewed, and cautions and limitations were discussed to avoid misinterpretations when we accomodate Korean population to this standard. Further researches were recommended to get better understanding of response characteristics of Korean to whole-body vibration.

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A study on Whole Body Vibration in Subway System (지하철 전동차에서의 전신진동 특성에 관한 연구)

  • Jeong, Sang Wook;Park, Sang Kyu
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.7 no.1
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    • pp.87-98
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    • 1997
  • In this study, subway train vibration has been measured to characterize the whole body vibration of Seoul subway lines for various human postures. Results show that the floor vibration level of the subway trains in the vertical direction is higher than that in other directions. At the standing human posture, vibration level of the head in the right-left direction are increased while that in the vertical direction is decreased. It is assumed that the different flexibility of the human body and the rolling motion of the subway trains are the main cause. At the sitting posture with back seat on, vibration level in the right and left direction at the human ischial tuberosities is lower than that in other directions. Results also show that there were little difference between back-seat on model and back-seat off model. Transmissibility analysis shows how the subway vibration affects the response of a human body.

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A Study on the Measurement of Whole-Body Vibration in Some Coal-fired Power Plant Workers

  • Heo, Seung-Moo;Lee, Yun Keun;Park, Hee Sok
    • Journal of the Ergonomics Society of Korea
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    • v.32 no.4
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    • pp.341-344
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    • 2013
  • Objective: This study measured and evaluated the characteristics of the whole body vibration experienced in some coal-fired power plant in Korea. Background: Few studies have been carried out in Korea about the effects of whole body vibration of power plants on humans. Method: The evaluation scheme suggested by the Law of Noise and Vibration Control was applied. Results: It was found that 28.9% of total measurement points were above the limit suggested by the law. Conclusion: Many workers are exposed to whole body vibration during their job completion, and more efforts should be applied to prevention and control of the plat vibration.

Analysis of mechanical properties of microtubules under combined effects of surface and body forces for free and embedded microtubules in viscoelastic medium

  • Farid, Khurram;Taj, Muhammad
    • Advances in concrete construction
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    • v.13 no.3
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    • pp.255-264
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    • 2022
  • Vibration is expected to occur in microtubules as tubular heterodimers. They oscillate like electric dipoles. Several research studies have estimated a frequency of vibration using the orthotropic model, a beam or rod like models and shell models, considering the surface forces. The effects of body forces on the dynamics of the microtubules were not yet taken into account. This study seeks to capture the body force effects on the vibration modes generated and on the corresponding frequency for microtubules. An orthotropic elastic shell model for the structural details of microtubules is used for the analysis. The tests are conducted out for microtubules, exposed to electro-magnetic and gravitational forces, the transverse vibration, radial mode vibration, and axial mode of vibration have accomplished. We therefore, evaluate and compare microtubules' frequencies with prior results of vibration frequency without the effects of body force.

Estimation of Vibration Level Inside an Engine Based on Rigid Body Theory and Measurement Technology (강체 운동 해석 및 실험을 통한 엔진 내부 진동 예측에 관한 연구)

  • Kim, Byung-Hyun;Park, Jong-Ho;Kim, Eui-Yeol;Lee, Sang-Kwon;Kim, Tae-Jeong;Heo, Jeong-Ki
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.11
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    • pp.1043-1050
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    • 2011
  • This paper presents practical results for the estimation of vibration level inside a powertrain based on the rigid body theory and measurement. The vibration level of inside powertrain has been used for the calculation of excitation force of an engine indirectly. However it was difficult to estimate or measure the vibration level inside of a powertrain when a powertrain works on the driving condition of a vehicle. To do this work, the rigid body theory is employed. At the first, the vibration on the surface of a powertrain is measured and its results are secondly used for the estimation the vibration level inside of powertrain together with rigid body theory. Also did research on how to decrease the error rate when the rigid body theory is applied. This method is successfully applied to the estimation of the vibration level on arbitrary point of powertrain on the driving condition at the road.

Experimental investigation on the apparent mass during exposure to whole-body vertical vibration for Korean-seated postures (한국인 앉은 자세에 대한 수직방향의 전신진동 피폭에 대한 겉보기 질량의 실험적 연구)

  • 김영태;정완섭;윤용산
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.241-245
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    • 2003
  • When considering the effects of whole-body vertical vibration, it is valuable to have an understanding of the mechanical characteristics (mechanical impedance and apparent mass) of the body. This paper addresses experimental results carried out to investigate the characteristics of apparent masses fer 41 Korean. The apparent masses of the seated human body in vertical direction were measured during different experimental conditions, such as vibration excitation level (0.5-2 ms$\^$-2/ r.m.s). frequency range (1-50Hz), and upper body posture (relaxed, normal and backrest-upright). We showed the average of all subjects and all conditions and compared the results with ISO5982/DIS (2000).

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Structure Design Optimization of Small Class Forklift for Idle Vibration Reduction (소형 지게차의 Idle 진동 저감을 위한 차체 구조 최적 설계)

  • Lee, Wontae;Kim, Younghyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.660-664
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    • 2014
  • A diesel forklift truck under 3-ton class has disadvantages in the vibration transmission path. Because the weight ratio of body structure to powertrain which is source of excitation force is lower th an a mid-class forklift. In addition, the torsional and bending vibration mode frequencies of body structure are within the engine excitation frequency range, then high idle vibration generated by resonance. In this paper vehicle body structure design and optimization technique considering idle vibration reduction are presented. Design sensitivity analysis is applied to search the sensitive of design parameters in body structure. The design parameters such as thickness and pillar cross section were optimized to increase the torsional and bending vibration mode frequencies.

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Effects of Consecutive whole Body Vibration Exercise using Heel Raise Posture on Neuromuscular Response during Single-leg Stance (뒤꿈치 들기 자세를 이용한 전신진동 운동이 외발서기 시 근신경 반응에 미치는 영향)

  • Kim, Dae Dong;Lee, Myeounggon;Youm, Changhong
    • Korean Journal of Applied Biomechanics
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    • v.31 no.2
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    • pp.104-112
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    • 2021
  • Objective: This study aimed to analyze the effects of consecutive whole body vibration through heel raise posture on the center of pressure and electromyography of anterior tibial muscle, lateral gastrocnemius and soleus muscles during single-leg stance. Method: The subjects of this study included 30 healthy males in their 20's, with the following inclusion criteria: no history of orthopaedic medical history, no participation in regular exercises, no history of whole body vibration exercise, and right leg being the dominant leg. The experimental procedure involved pretreatment measurement of eye open single-leg stance, application of whole body vibration for 30 seconds, post-treatment measurement (3 measurements in total). Static and dynamic movements have been measured over 2 separate experiments, with 72 hours gap between the experiments. Static movement involved maintaining single-leg heel raise posture for 30 seconds while applying whole body vibration, and dynamic movement involved heel raise (15 repetitions over 30 seconds) while applying whole body vibration. The strength of applied whole body vibration was 35 Hz frequency and 2~4 mm amplitude. Results: As the single-leg posture after static heel raise posture, mediolateral velocity of the center of pressure at post 2 and post 3 were significantly reduced compared to the pre-treatment measurement. In addition, the percentage for reference voluntary contraction in anterior tibial muscle and soleus and median frequency at anterior tibial muscle and lateral gastrocnemius muscle at post 3 were significantly decreased compared to the pre-treatment value. As the single-leg posture after dynamic heel raise posture, the mediolateral 95% edge frequency of the center of pressure and median frequency at anterior tibial muscle, lateral gastrocnemius muscle, and soleus muscle at post 3 were significantly reduced compared to the pre-treatment value. Conclusion: Acute whole body vibration via static and dynamic heel raise posture have positive effect on mediolateral posture control during single-leg stance.

Measurements of Whole-body Vibration Exposed from UH60-Helicopter and Their Analysis Results (UH60 헬기 조종사의 피폭진동 측정 및 평가 결과)

  • Cheung, Wan-Sup;Byeon, Joo-Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.132-137
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    • 2005
  • This paper addresses what amount of whole-body vibration is exposed to pilots of UH60 helicopters during flight. To measure the whole-body exposed from the feet and seat, the 12-axis vibration measurement system was used. It enables simultaneous measurement of vibration exposure from the body contact area of the feet, hip and back. The measured 12-axis vibration signals are exploited to the comfort level of UH60 helicopters during flight. It is shown that the evaluated ride value is close to $0.74{\sim}0.79m/s^2$ and that it is equivalent to the semantic scale of 'fairly uncomfortable'. To assess the health effects of whole-body vibration exposed to pilots of UH60 helicopters during their flight, the rms-based and VDV(vibration dose value)-based evaluation results of measured four-axis vibration signals are shown in this work. The fatigue-decreased proficiency limit, whose level is half of the exposure limit, is expected to come after the two-hour flight. The exposure limit is shown to reach after the 10-hour flight.

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The Nonlinear Simulation on the Selection of Suitable Suspension Considering Human Vibration (인체 진동을 고려한 최적 현가장치의 선정에 관한 비선형 모의실험)

  • 김진기;홍동표;최만용
    • Journal of KSNVE
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    • v.10 no.2
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    • pp.247-253
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    • 2000
  • The evaluation of the ride quality had been performed by the subjective method before ISO2631(International Organization for Stadard 2631) and BS6841(British Standard 6841) was precented, but many research programs have been performed by the objective method after that. On this study, the ride quality was evaluated related with the objective method which considered the vibration which the human body feels on the driver's seat while driving on the road. In particular, we made the shock absorber nonlinear model and also selected the suitable shock absorber in the part of the vibration which the human body feels into the simulation. The shock absorber of suspension was dealt with 3 cases respectively with the front wheel and rear wheel. The vibration of the car driving on the road can be transferred to the wheel, the suspension, the vehicle body, the seat and the human body. The signal which was gained from the seat(hip) and the floor(foot) of the human body was changed to the vibration signal which the human body felt through using the frequency weighting function. And then the performance of the shock absorber was calculated through the statistic processing.

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