Measurement and Frequency Weighting Functions for Human Vibration

Dohyung Kee,Hee Sok Park 대한인간공학회 2013 大韓人間工學會誌 Vol.32 No.4

Objective: The aim of this study is to review and summarize human vibration measurement process, and necessity and methods of frequency weightings for human vibration. Background: Prolonged human exposure to hand-arm vibration and whole-body vibration can result in a range of adverse conditions and the development of occupational diseases such as vibration white finger. For preventing these adverse effects, it is important to correctly apply human vibration measurement process. Method: This manuscript was based on the review and summary of mechanical and human vibration relevant texts, academic papers, materials obtained through web surfing. Results: This manuscript summarizes human vibration measurement process described in ISO standards and relevant texts. The sensitivity of the human body to mechanical vibration is known to be dependent on both the frequency and direction of vibration. To take this into account, varying frequency weighting functions have been developed, and RMS frequency-weighted accelerations are used as the most important quantity to evaluate the effects of vibration on health. ISO provided nine frequency weighting functions in the form of curves and tables. Researches on frequency weightings are focused on development and validation of new frequency weightings to truly reflect the relationship between vibration exposure and its adverse effects. Application: This would be useful information for systematically applying human vibration measurement and analysis process, and for selecting appropriate frequency weighting functions.

수지진동에서의 진동강도, 손잡이온도, 소음 및 미는 힘의 복합효과에 따른 악력 및 지단피부온의 변화

Koh, Kyung-Sim,Griefahn, B.,Fritz, M.,Brode, P. 대한예방의학회 1994 Journal of Preventive Medicine and Public Health Vol.27 No.4

Recent studies reveal that grip forces during the hand-arm vibration are most significant for the genesis of vibration-induced white linger syndrome. Therefore, exerted grip forces and skin temperatures of fingers were regarded as dependent variables in experiments and the effects of grip temperature, noise, pushing force, vibration and the combined effect of vibration and pushing force were studied. The objectives of the present study were, first, to varify and compare the changes of grip force affected by grip temperature, noise, pushing force, vibration and the combined effect of vibration and pushing force and, second, to observe the reaction of finger skin temperature affected by above factors. Forty-six healthy male students ($25.07{\pm}2.85$) participated in five systematically permuted trials, which endured 4 minutes each other. Experiments were executed in a special chamber with an air temperature of 21C. In each experiments, the subjects were exposed to five experiment types: (1) grip force of 25N only, (2) pushing force of 50N, (3) acceleration of vibration $7.1m/sec^2(z-direction)$, (4) pink noise of 95 dB (A) and (5) combination of pushing force 50N and acceleration of vibration $7.1m/sec^2$. A repeated-measures analysis of variance (ANOVA) was performed on the grip force to test whether it was affected by noise, pushing force, vibration and pushing force. The present results show that vibration was significantly related to the increase of grip force, but the other factors, such as pushing force, noise and grip temperature had no signigicant influence on the increase of grip force, and that the reaction of finger skin temperature were significantly affected by the skin temperature at start of experiment and grip temperature, not grip force and other experimental conditions. Therefore, we suggest that the management for decreasing the grip force is meaningful to prevent the occurrence of Hand-arm vibration syndrome (HAVS).

교육매체 활용 : 교육용 복합 진동실험장치 개발

임경화 ( Kyung Hwa Rim ),박근윤 ( Geun Yun Park ),유호민 ( Ho Min Ryu ),최우철 ( Woo Cheol Choi ),문승준 ( Seong Jun Moon ),신혜정 ( Hye Jung Shin ) 한국실천공학교육학회 2010 실천공학교육논문지 Vol.2 No.2

진동학은 움직이는 기계 구조물의 설계에 기본이 되는 학문으로 진동 절연, 흡수 등에 관한 방법론과 현장에서 발생하는 다양한 진동문제에 대한 해석 수행 능력을 배우는 학문이다. 하지만 진동학은 기계공학에서 다른 역학과 목들에 비해 이해하기 어려운 교과목이기 때문에 진동학 이론의 물리적인 이해를 돕기 위해 진동학 관련 교육장 비 개발이 매우 필요한 상황이다. 이에 본 논문에서는 진동학의 이론적인 내용을 실험을 통하여 학생들이 보다 쉽게 진동학의 물리적인 의미를 깨달을 수 있도록 도와주는, 그리고 실험과정이 간단한 교육용 복합 진동실험장치를 개발하고 그 적용효과를 알아보고자 한다. 다자유도 진동, 보 진동, 현 진동 및 판 진동의 4가지 대표적인 진 동현상을 실험할 수 있는 복합 진동실험 장치를 개발하고 적용범위를 제시한다. 마지막으로 설문조사를 통하여 학 업성취 반응도평가 및 개선방안을 제안한다. As the basic knowledge during designing most moving mechanical structures, vibration engineering is a subject teaching the theory on vibration control and isolation, which also cultivating the ability of analyze variety of vibration problems. However, vibration engineering is more difficult to understand than other dynamics courses in mechanical field, so the development of educational equipments in order to help understanding physical theory of vibration is really necessary. So in this paper we could see the effect after doing simple experiment process using the educational vibration equipment with multiple function, students could easily understand physical theory of vibration. The educational vibration equipment with multiple function and its application range are introduced, which could performance four kinds of typical vibration phenomenon: vibration of multidegree of freedom system, vibration of beam, vibration of beam, and vibration of plate. Finally, assessments of response and improvement plan are proposed through a survey.

진동절연재로 보강된 기둥부재의 진동저감효과 및 구조적 거동분석

김진호,이나현,허진호,김희규 한국구조물진단유지관리공학회 2016 한국구조물진단유지관리공학회 논문집 Vol.20 No.4

For elevated railway station on which track is connected with superstructure of station, structural vibration level and structure-borne-noise level has exceeded the reference level due to structural characteristics which transmits vibration directly. Therefore, existing elevated railway station is in need of economical and effective vibration reduction method which enable train service without interruption. In this study, structural vibration non-transmissible system which is applied to vibroisolating material for column member is developed to reduce vibration. That system is cut covering material of the column section using water-jet method and is installed with vibroisolating material on cut section. To verify vibration reduction effect and structural performance for structural vibration non-transmissible system, impact hammer test and cyclic lateral load test are performed for 1/4 scale test specimens. It is observed that natural period which means vibration response characteristics is shifted , and damping ratio is increased about 15~30% which means that system is effective to reduce structural vibration through vibration test. Also load-displacement relation and stiffness change rate of the columns are examined, and it is shown that ductility and energy dissipation capacity is increased. From test results, it is found that vibration non-transmissible system which is applied to column member enable to maintains structural function. 궤도가 역사의 상부에 위치하여 열차운행으로 인하여 발생한 진동이 직접 전달되는 선하역사에서 구조물 진동과 이로 인한 구조물 기인 소음이 기준치보다 높은 것으로 나타남에 따라, 기존 선하역사에 대하여 열차 운행의 중단 없이 진동저감이 가능한 경제적, 효율적 방안이 요구된다. 이에 본 연구에서는 진동전달 경로상의 기둥에 워터젯 공법으로 기둥단면에서 피복재 부분을 파쇄한 후 진동전달 절연기능을 가지는 에폭시 소재의 방진재를 보강하여 진동을 저감시키기 위한 구조진동절연시스템을 개발하였다. 방진재의 보강체적을 변수로 한 진동절연시스템을 실제역사 기둥의 1/4축소모형에 적용하고, 충격가진 시험을 통한 진동저감 성능과 횡하중 반복가력시험을 통한 구조적 성능을 검증하고자 하였다. 충격가진 실험결과로부터 구조진동절연시스템을 적용할 경우 고유 진동주기가 하향되어 진동응답 특성이 변화되고 감쇠비는 약 15~ 30%까지 증가를 나타내어 진동저감 성능이 있음을 알 수 있었다. 또한 반복하중 가력에 의한 구조성능 실험에서 하중-변위 및 강성변화에 대한 고찰과 연성도 및 에너지 소산의 증가를 보인 결과로 부터 구조부재로의 기능을 유지함을 확인 할 수 있었다.

수리온 인체진동 영향성 평가

정세운,곽동일,김세희,황유상 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.4

헬리콥터의 진동은 조종사와 승객의 안락함을 결정하는 주요인이며, 점차 높아지는 안락함에 대한 요구 수준에 대응하기 위한 진동저감 관련 연구가 꾸준히 진행되고 있다. 인체진동은 진동에 노출된 조종사와 승객에 대한 안락함과 건강에 미치는 영향을 평가하기 위해 활용되고 있다. 또한, 진동에 노출된 인체에 대한 평가는 인체진동을 향상시키기 위한 연구에 활용하고 있다. 국내 최초로 개발된 수리온 헬리콥터에서도 다양한 진동저감장치가 적용되어 있으며, 국제표준 ISO 2631-1(Mechanical vibration and shock-Evaluation of human exposure to whole body vibration)을 적용하여 수리온에 대한 인체진동 평가를 수행하였다. 본 논문에서는 수리온 진동에 노출된 인체에 대한 평가 방법과 결과를 제시한다. The major factor for pilot and passenger comfortable in cockpit and cabin is vibration of the helicopter, and the research for helicopter vibration reduction is in progress corresponding to the demand for increased comfort level. The human vibration has been used to evaluate comfort and health for pilot and passenger who are exposed to vibration. Also, the evaluation of human exposure to vibration has been used to improve comfort and health with regards of human vibration. For Surion that is first korean-developed helicopter and has appropriate vibration-reduction devices, the evaluation of human vibration was conducted according to ISO 2631-1(Mechanical vibration and shock-Evaluation of human exposure to whole body vibration). This paper presents the evaluation method and results of human exposure to Surion vibration.

저소음 프로펠러 개발을 위한 프로펠러 진동특성 추정에 대한 연구

공연권 한국방위산업학회 2023 韓國防衛産業學會誌 Vol.30 No.2

선박 프로펠러의 진동은 날개의 손상 및 소음을 유발할 수 있으며 저소음 프로펠러를 설계하기 위해서는 프로펠러의 진동특성을 정확도 높게 추정하여 설계에 반영하여야 한다. 본 연구에서는 프로펠러의 진동특성을 정확도 높게 추정하기 위해 날개들과 허브가 전부 포함되고 날개의 요소 수가 기존 연구에 비해 약 2.2배 증가된 프로펠러 유한요소모델을 제작하였다. 기존 연구의 방법인 날개 유한요소모델에 대한 고유진동해석, 허브 상・하면이 고정 또는 고정되지 않은 프로펠러 유한요소모델에 대한 고유진동해석을 수행하였다. 고유진동해석을 통해 프로펠러의 진동특성인 고유진동수 및 모드형상을 추정하였으며추정 결과를 분석하여 프로펠러 허브가 날개 진동에 미치는 영향을 확인하였다. 또한 Impact test(충격가진시험)를 수행하였고 결과를 진동특성 추정 결과와 비교하여 진동특성 추정의 정확도를 분석하였다. 그 결과, 프로펠러에는 고유진동수와 날개모드형상이 서로 유사한 모드들이 존재했는데, 이러한 현상은 날개 진동이 허브를 통해 다른 날개의 진동에 영향을 미치는연성효과 때문에 발생하였다. 또한 프로펠러 허브는 연성효과와 허브 진동에 의해 날개 진동에 영향을 미치며 허브 상・하면이 고정되면 허브 진동은 날개 진동에 영향을 미치지 않았다. 이로부터 프로펠러의 진동특성을 정확도 높게 추정하기 위해서는 프로펠러 날개만이 아닌 프로펠러 전체에 대한 진동해석을 수행해야 함을 도출하였다. Vibration of ship propellers can cause damage to blades and propeller noise, in order to design low-noise propellers the vibration characteristics of propellers must be estimated to a high degree of accuracy and reflected in the design. In this study, in order to estimate the propeller vibration characteristics with high degree of accuracy, a propeller finite element model was created that included the hub and all blades of the propeller and increased the number of finite elements of the blades by about 2.2 times compared to previous studies. The free vibration analysis of the blade finite element model which was a method of previous studies, and the free vibration analysis of the propeller finite element model with fixed or unfixed upper and lower surfaces of the hub were performed. Natural frequencies and mode shapes, which are vibration characteristics of the propeller, were estimated through free vibration analysis, and the effect of the propeller hub on blade vibration was confirmed by analyzing the estimation results. In addition, an impact test was performed, and the accuracy of the estimation of the vibration characteristics was analyzed by comparing the test results with the estimation results of the vibration characteristics. As a result, the propeller have modes with similar natural frequencies and blade mode shapes, this phenomenon occurs because of the coupling effects in which the vibration of a blade affects the vibration of another blade through a hub. The propeller hub affects the blade vibration by the coupling effects and the hub vibration and when the upper and lower surfaces of the hub are fixed, the hub vibration does not affect the blade vibration. In order to estimate the vibration characteristics of the propeller with high degree of accuracy, it was derived that vibration analysis should be performed for the propeller, not just the propeller blade.

The relevant factors of work-related fatigue for occupational vibration-exposed employees

YongDuk Ahn,Jeongbae Rhie,Min-Gi Kim 대한직업환경의학회 2022 대한직업환경의학회지 Vol.34 No.-

Background: To date, little is known about the effects of factors linked to work-related fatigue on vibration-exposed workers. Thus, the purpose of this study was (1) to assess the effects of vibration exposure time per week and work-related fatigue on workers and (2) to identify factors associated with work-related fatigue caused by long-term exposure to occupational vibration. Methods: This study used data collected from the 5th Korean Working Conditions Survey. A total of 34,820 non-vibration-exposed and 10,776 vibration-exposed employees were selected from the data. The χ2 and multiple logistic regression were used to determine the effect of vibration exposure time per week and the effects of factors of work-related fatigue on workers. Results: The prevalence of work-related fatigue in vibration-exposed workers (30.5%) was higher than that of non-exposed workers (15.9%). The prevalence of work-related fatigue was higher for female and workers with depression, anxiety, and shift work, and those with authority to control their work pace had statistically significantly higher odds than those who did not. The employees who had the authority to control their order of work (odds ratio [OR]: 0.88; 95% confidence interval [CI]: 0.81–0.95) and method of work (OR: 0.90; 95% CI: 0.82–0.98) had statistically significantly lower odds than those who did not. The OR of workrelated fatigue symptoms was highest among employees whose vibration exposure time per week were 30.0%–40.0% (OR: 2.36; 95% CI: 1.96–2.83). Lower OR was observed as vibration exposure time per week decreased. Conclusions: The results of the present study suggest an association between occupational vibration and work-related fatigue and longer vibration exposure time per week, causing an increased prevalence of work-related fatigue symptoms. Measures to protect workers exposed to occupational vibration from work-related fatigue must be taken.

전신진동운동이 건강한 성인의 가자미근 신경-근 활성화에 미치는 영향

최동성 한국생활환경학회 2019 한국생활환경학회지 Vol.26 No.5

The purpose of this study was to investigate the effects of vibration frequency during whole-body vibration exercise on the soleus H-reflex in healthy adults. Fourteen Healthy adults was participated in this study. They performed whole-body vibration exercises in 4 vibration intensity conditions (No vibration, 10Hz 4 mm, 20Hz 4 mm and 27Hz 4 mm). The soleus H-reflex of right side was measured during the whole-body vibration exercise. The amplitude of H-reflex and M-wave, H/Mmax ratio were compared with one-way repeated measures of ANOVA (p<0.05) among four different vibration frequency. There were the significant differences in the amplitude of H-reflex according to vibration frequency (F=15.802, p<0.001). H-reflex was significantly reduced at 10Hz (p<0.01), 20Hz (p<0.001) and the 27Hz (p<0.01) than at No vibration. There were the significant differences in H/Mmax ratio according to vibration frequency (F=14.910, p<0.001). H/Mmax ratio was significantly reduced at 10Hz (p<0.05), 20Hz (p<0.01) and the 27Hz (p<0.01) than at No vibration. This study suggest that it might be not effective to apply an the vibration frequency of 10Hz or more during whole-body vibration exercise for proceeding of neuro-muscular activity in healthy adults.

진동작업 종사 근로자의 진동노출 실태에 관한 연구

김갑배(Kab Bae Kim),정은교(Eun-Kyo Chung) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.4

In Korea, researches on the exposure assessment of the hand-transmitted vibration started from the mid-90, however, they were performed in the limited industries such as auto-assembly plants and the evaluation of the vibration was mostly conducted by ISO 5349(1986). Therefore, it was necessary to assess hand-transmitted vibration levels of workplace such as ship building/repairing industry or mining industry where occupational injuries are largely occurred and to evaluate the vibration levels using revised ISO 5349(2001). The SVAN 949 Four Channels Sound & Vibration Analyser was used for the measurement. The workers using a chain saw were exposed to 1.7 ~ 2.8 ㎨ of daily vibration level. Workers using a rock drill in a coal mining were exposed to the highest vibration acceleration among workers and the levels were 7.1 ~ 10.8 ㎨. Vibration levels of grinders were different according to the types of grinders. The hand-transmitted vibration of 3 types of grinders were measured and the levels were 3.3 ~ 11.1 ㎨. Workers using a impact wrench were exposed to 1.5 ~ 1.6 ㎨ of vibration. Out of 20 kinds of machines, only 4 tools provided the information of vibration acceleration on the instructions. In addition, the current condition of workplaces to control vibration was not much different from the past because there are no vibration exposure limit.

Attention decrease of drivers exposed to vibration from military vehicles when driving in terrain conditions

Park, D.J.,Choi, M.G.,Song, J.T.,Ahn, S.J.,Jeong, W.B. Elsevier 2019 International journal of industrial ergonomics Vol.72 No.-

<P><B>Abstract</B></P> <P>In this study, we analyzed the phenomenon of reduced attention for 11 subjects using a 6-degree-of-freedom synthetic vibration platform to simulate the vibration from terrain driving. Military vehicles are mainly used in terrain conditions, and drivers are exposed to whole-body vibrations for long periods of time. Drivers not only have trouble with comfort and health, they also suffer decreased attention. This decrease has a negative effect on driving. The vibration signal of a military vehicle on terrain is simulated using a synthetic vibration platform. Eleven subjects experienced these synthesized field-terrain vibrations while on the vibration platform performing a variety of perceptual and cognitive attention tests. The attention tests were divided into perceptual and cognitive, and the decrease in attention caused by vibration exposure and the exposure time was analyzed. From the results, automatic perceptual attention was not affected by vibration exposure. When the complexity of cognitive processing was increased during the attention test, the effects of vibration exposure became significant. The decrease in certain attention mechanisms was found when drivers were exposed to whole-body vibrations. Thus, it is expected that drivers are adversely affected when performing missions. We analyze the correlation between vibration exposure and attention decrease in this study, and the ability of the military vehicle driver to perform his mission can be predicted.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Decrease in attention was tested among military-vehicle drivers exposed to whole-body vibrations in terrain conditions. </LI> <LI> The vibration signal of a military vehicle on terrain was simulated using a synthetic vibration platform. </LI> <LI> Eleven subjects experienced these terrain vibrations operating the synthetic vibration platform and performed attention tests. </LI> <LI> A decrease of attention was found when drivers were exposed to whole-body vibrations. </LI> </UL> </P>