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.

시내버스의 전신진동 평가

정재열 카톨릭대학산업의학센타 산업의학연구소 1999 韓國의 産業醫學 Vol.38 No.4

본 연구는 대중교통으로 이용되고 있는 시내버스에 승차한 승객들이 노출되는 전신진동 수준을 신형 버스와 구형버스의 각각 5곳의 위치에서 ISO 2631/1(ISO,1978)의 방법을 이용하여 측정하고 그 결과를 이용해 승객들이 유해한 건강영향 없이 노출될 수 있는 전신진동의 피로-감소숙달(Fatigue-Decreased Proficiency:FDP)경계 그리고 전신진동 유해성 평가에 이용되는 충격계수를 제시하고자 수행되었다. 진동수준의 측정에 이용되었던 버스는 모 회사에서 생산된 신형버스(540L)와 구형버스(RB520L)이었고 결과는 아래와 같다 1. 신형버스의 바닥에서 측정되었던 등가진동수준은 Xh 축의 경우 평균 86.5dB(FDP: 872분 86초),Yh 축의 경우 평균 85.1dB(FDP: 1076분 77초), Zh 축의 경우 평균 93.4dB(FDP:294분 91초) 이었다. 구형버스의 바닥에서 측정되었던 등가진동수준은 Xh 축의 경우 평균 85.0dB(FDP: 1092분 73초), Yh 축의 경우 평균 90.9dB(FDP: 440분 9초), Zh 축의 경우 평균 102.9dB(FDP: 49분 31초)잉ㅆ다. 신형버스와 구형버스 바닥의 등가진동수준을 비교해 볼 때 Xh 축에서는 2 위치에서, Yh과 Zh 축에서는 모든 위치에서 구형버스가 신형버스보다 높은 등가진동수준을 나타냈다. 신형버스와 구형버스 바닥의 진동이 단일 방향에서만 발생하고 하루 승객들의 버스 이용시간이 50분으로 고려할때 구형버스의 Zh 축만이 ISO 2631 FDP 기준에서 벗어난다. 신형버스와 구형버스 바닥의 등가진동수준을 비교해 볼 때 Xh 축에서는 2 위치에서, Yh과 Zh 축에서는 모든 위치에서 구형버스가 신형버스보다 높은 등가진동수준을 나타냈다. 신형버스와 구형버스 바닥의 진동이 단일 방향에서만 발생하고 하루 승객들의 버스 이용시간이 50분으로 고려할 때 구형버스의 Zh 축만이 ISO 2630 FDP 기준에서 벗어난다. 2. 신형버스의 좌석에서 측정되었던 등가진동수준은 Xh 축의 경우 평균 83.9dB(FDP: 1288분 66초), Yh 축의 경우 평균 84.1dB(FDP: FDP 1257분 7초), Zh 축의 경우 평균 91.6dB(FDP: 394분 55초)이었다. 구형 버스의 좌석에서 측정되었던 등가진동수준은 Xh 축의 경우 평균 89.0dB(FDP: 592분 48초),Yh 축의 경우 평균 90.7dB(FDP: 452분 20초), Zh 축의 경우 평균 106.0dB(FDP: 19분 78초)이었다. 신형버스와 구형버스 좌석의 진동이 단일 방향에서만 발생하고 하루 승객들의 버스 이용시간이 50분으로 고려할 때 구형버스의 Zh 축만이 ISO 2631 FDP 기준에서 벗어난다. 3. 신형버스의 바닥에서 측정되었던 충격계수는 Xh 축의 경우 평균 6.38이었다. 구형버스의 바닥에서 측정되었던 충격계수는 Xh 축의 경우 평균 5.50, Yh 축의 경우 평균 5.57, Zh 축의 경우 평균 6.41 이었다. Xh 축을 제외하면 위치와 방향에 따라 다소의 차이는 있었지만 전체적으로 구형버스의 바닥에서 더 높은 충격계수를 나타냈다. 4. 신형버스의 좌석에서 측정되었던 충격계수는 Xh 축의 경우 평균 5.06, Yh 축의 경우 평균 4.68, Zh 축의 경우 평균 5.59이었다. 구형버스의 좌석에서 측정되었던 충격계수는 Xh 축의 경우 평균 5.44, Yh 축의 경우 평균 4.83, Zh 축의 경우 평균 6.18이었다. 위치와 방향에 따라 다소의 차이는 있었지만 Xh, Yh, Zh 방향에서 전체적으로 구형버스의 좌석에서 더 높은 충격계수를 나타내어 바닥에서의 방향과 위치별 충격계수와 다른 양상을 나타냈다. 5. 신형버스에서 평균 벡터합은 바닥에서 1.01m/s2 (FDP: 90qns 63ch) rmflrh whktjrdptj 0.75m/s2(FDP: 147분 12초)이었다. 구형버스에서 평균 벡터합은 바닥에서 2.63m/s2(FDP: 4분 59초) 그리고 좌석에서 2.04m/s2(FDP: 18분 34초)이었다. This study was performed to measure the whole-body vibration level with respect to ISO 2631/1 method and it's fatigue-decreased proficiency boundary in 5 locations of new and old model city buses used for mass transportation and suggest the fatigue-decreased proficiency(FDP) boundary of whole-body vibration without deleterious health effects to the passengers and the crest factor used for the jazardous evaluation of whole-body vibration. City buses, new model bus(540L) and old model bus(RB 520L) used for the measurement of whole-body vibration were manufactured by one of the automobile manufacturing companies in Korea and the results were as follows: 1. Means of energy equivalent vibration level measured on the floor of new bus were 86.3dB(FDP: 873minutes and 86seconds) on Xh axis, 85.1dB(FDP: 107minutes and 77seconds) on Yh axis and 93.4dB(FDP: 294minutes and 91seconds) on zh axis. Means of energy equivalent vibration level measured on the floor of old bus were 85.0dB(FDP: 1092minutes and 73seconds) on Xh axis, 90.9dB(FDP: 440minutes and 09seconds) on Yh axis and 102.9dB(FDP: 49minutes and 31seconds) on Zh axis. Comparing the energy equivalent vibration level between new and old buses, old bus showed higher vibration level to the location 2 on Xh axis and all locations on Yh and Zh axes than new bus. Considering the vibration's direction in new and old buses is only one axis and daily using time of passenger to bus in 50 minutes, only one axis, Zh of old bus is out of ISO 2631's FDP criteria. 2. Means of energy equivalent vibration level measured on the seat of new bus were 83.9dB(FDP: 1288minutes and 66seconds) on Xh axis, 84.1dB(FDP: 1257minutes and 7seconds) on Yh axis and 91.6dB(FDP: 394minutes and 55seconds) on Zh axis. Means of energy equivalent vibration level measured on the seat of old bus were 89.0dB(FDP: 592minutes and 48seconds) on Xh axis, 90.7dB(FDP: 452minutes and 20seconds) on Yh axis and 106.0dB(FDP: 19minutes and 78seconds) on Zh axis. Comparing the energy equivalent vibration level between new and old buses, old bus showed higher vibration level to all locations on Xh, Yh and Zh axes than new bus. Considering the vibration's direction in new and old buses is only one axis and daily using time of passenger to bus is 50 minutes, only one axis, Zh of old bus is out of ISO 2631's FDP criteria. 3. Means of crest factor measured on the floor of new buses were 5.59 on Xh axis, 5.16 on Yh axis and 6.38 on Zh axis. Means of crest factor measured on the floor of old bus were 5.50 on Xh axis, 5,57 on Yh axis and 6.41 on Zh axis. Excluding Xh axis of new and old model buses, there are differences of crest factor on the directions and axes more or less but old bus showed higher crest factor than new bus. 4. Means of crest factor measured on the seat of net bus were 5.06 on Xh axis, 4.68 on Yh axis and 5.59 on Zh axis. Means of Crest factor measured on the seat of old bus were 5.44 on Xh axis, 4.83 on Yh axis and 6.18 on Zh axis. Old bus showed higher crest factor on the directions and axes than new bus. 5. Means of vector sum in new bus were 1.01㎨(FDP: 90minutes and 63seconds) on floor and 0.75㎨(FDP: 147minutes and 12seconds) on seat. Means of vector sum in old bus were 2.63㎨(FDP: 4minutes and 59seconds) on floor and 2.04㎨(FDP: 18minutes and 34seconds) on seat.

UH60 헬기 조종사의 피폭진동 측정 및 평가 결과

정완섭(Cheung, Wan-Sup),변주현(Byeon, Joo-Hyun) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.12

This Paper addresses what amount of whole-body vibration is exposed to Korean pilots of UH60 helicopters during their mission flight. To measure the expose4 whole-body vibration, the 12-axis whole-body vibration measurement system was used. It enables the direct measurement of whole-body vibration exposed from the body contact area consisting of the feet, hip and back. The measured 12-axis vibration signals were used to evaluate the vibration comfort level experienced by the pilots of UH60 helicopters. The evaluated vibration comfort level is found to be closeto 0.74-0.79m/s, which is equivalent to the semantic scale of 'fairly uncomfortable'. To assess the health effects of whole-body vibration exposed to Korean pilots of UH60 helicopters during their mission flight, the rms-based and VDV(vibration dose value)-based evaluation schemes, recommended by ISO 2631-1:1977, were exploited in this work. The evaluated results indicate that Korean pilots cannot avoid the fatigue-decreased proficiency limit after two-hour continuous flight. The whole-body vibration level exposed from the UH60 helicopters during continuous 10-hours mission flight is found to reach to the vibration exposure limit.

Sn-Ag-Cu-X 무연솔더로 솔더링 된 접합부의 진동파괴 거동

진상훈,강남현,조경목,이창우,홍원식,Jin, Sang-Hun,Kang, Nam-Hyun,Cho, Kyung-Mox,Lee, Chang-Woo,Hong, Won-Sik 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.2

Environmental and health concerns over the lead have led to investigation of the alternative Pb-free solders to replace commonly used Pb-Sn solders in microelectronic packaging application. The leading candidates for lead-free solder alloys are presently the near eutectic Sn-Ag-Cu alloys. Therefore, extensive studies on reliability related with the composition have been reported. However, the insufficient drop property of the near eutectic Sn-Ag-Cu alloys has demanded solder compositions of low Ag content. In addition, the solder interconnections in automobile applications like a smart box require significantly improved vibration resistance. Therefore, this study investigated the effect of alloying elements (Ag, Bi, In) on the vibration fatigue strength. The vibration fatigue was conducted in 10~1000Hz frequency and 20Grms. The interface of the as-soldered cross section close to the Cu pad indicated the intermetallic compound ($Cu_6Sn_5$) regardless of solder composition. The type and thickness of IMC was not significantly changed after the vibration test. It indicates that no thermal activities occurred significantly during vibration. Furthermore, as a function of alloying composition, the vibration crack path was investigated with a focus on the IMCs. Vibration crack was initiated from the fillet surface of the heel for QFP parts and from the plating layer of chip parts. Regardless of the solder composition, the crack during a vibration test was propagated as same as that during a thermal fatigue test.

무작위 진동에 노출된 항공기 탑재 장비의 주파수영역 피로수명 평가

정현수(Hyun Su Jung),김기승(Ki Seung Kim),김준수(Jun Su Kim),이성우(Seong Woo Lee) 한국항공우주학회 2017 韓國航空宇宙學會誌 Vol.45 No.8

항공기에 탑재된 레이더 장비는 무작위진동 환경에 장기간 노출되어, 설계 시 피로수명 예측이 중요한 요소로 고려된다. 피로수명을 예측하는 방법 중 주파수영역 피로해석 방법이 지속적으로 제안되고 있다. 본 논문은 많이 사용되는 4가지의 주파수영역 피로해석 방법을 선정하여, 시편 피로시험 결과와 비교하였다. Strain gage를 이용한 시편 피로시험을 통해 시간영역 피로해석과 주파수영역 피로해석 방법을 비교한 결과, Dirlik과 Benasciutti-Tovo방법이 주파수영역 피로해석법 중 시간영역 피로해석법과 잘 일치하였다. 시편 피로시험 결과를 토대로 Dirlik과 Benasciutti-Tovo방법과 유한요소모델을 이용하여 항공기 탑재 장비의 피로해석을 수행하였으며, 요구수명이 만족함을 확인하였다. Expecting fatigue life of mounted radar in aircraft is very important when designing, because the mounted radar in aircraft is exposed to long-term external random vibration. Among the methods of predicting the fatigue life, Fatigue analysis method in frequency domain has continuously been proposed in this field. In this paper, four fatigue analysis methods in frequency domain, which are widely used, have been selected and compared with the results for Specimen fatigue test. As a result, Dirlik and Benascicutti-Tovo methods have been matched better with fatigue analysis in time domain than the method in frequency method through the comparison between the fatigue analysis method in time domain and the method in frequency domain by conducting the specimen fatigue test with strain gage. Based on the results of the specimen fatigue test, We have conducted fatigue analysis of mounted radar in aircraft with Dirlik and Benasciutti-Tovo methods in the finite element model, and confirmed that the required life was satisfying.

주조 알루미늄합금 A356을 사용한 해상구조물의 진동피로수명평가

김지억(Jie-Eok KIM),양성철(Sung-Chul Yang),정화영(Hwa-Young Jung),조기대(Ki-Dae Cho),강기원(Ki-Weon Kang) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.4

함정구조물은 함내 엔진 및 프로펠러 추진력의 환경진동에 노출되어 있다. 일반적으로 함상구조물은 함상진동규격인 MIL-STD-167-1A에 따라 개발되고 있으며, 장기간 사용을 목적으로 하는 함상구조물의 진동에 대한 피로수명은 해석적 접근법과 진동실험을 통해 반드시 평가되야 한다. 본 논문에서는 함상구조재로 사용된 주조 알루미늄합금인 A356의 피로강도를 14 S-N 법으로 평가하고, 구조물의 작용응력은 함상진동규격에 준하는 주파수응답해석을 수행하였다. 최대등가응력의 주파수는 최대실험주파수에서 나타났으며, 함상장비의 진통피로수명은 누적손상법에 의해 평가되었다. The naval structure exposes to environmental vibration of shafted propeller propulsion and engine vibration. In generally, shipboard equipments are developed compliance to MIL-STD-167-1A. For this purpose, vibration fatigue life of shipboard equipment for long lives should be estimate an analytical approach and vibration test. In this paper, High cycle fatigue strength of cast aluminum alloy A356 using shipboard equipment was evaluated by 14 S-N method. The applied stress of structure analyzes an analytical approach (frequency response analysis with sinusoidal input and a fatigue evaluation) to simulate a MIL-STD-167-1A test. The frequency with the maximum equivalent stress is shown by Max. test frequency and the vibration fatigue life of shipboard equipment was estimated by Miner's rule.

주조 알루미늄합금 A356 을 사용한 해상구조물의 진동피로수명평가

조기대(Ki-Dae Cho),김지억(Jie-Eok KIM),양성철(Sung-Chul Yang),정화영(Hwa-Young Jung),강기원(Ki-Weon Kang) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.9

함정구조물은 함내 엔진 및 프로펠러 추진력의 환경진동에 노출되어 있다. 일반적으로 함상구조물은 함상진동규격인 MIL-STD-167-1A 에 따라 개발되고 있으며, 장기간 사용을 목적으로 하는 함상구조물의 진동에 대한 피로수명은 해석적 접근법과 진동실험을 통해 반드시 평가되야 한다. 본 논문에서는 함상구조재로 사용된 주조 알루미늄합금인 A356 의 피로강도를 14 S-N 법으로 평가하고, 구조물의 작용응력은 함상진동규격에 준하는 주파수응답해석을 통해 분석되었다. 최대등가응력의 주파수는 최대실험주파수에서 나타났으며, 함상장비의 진동피로수명은 누적손상법에 의해 평가되었다. The naval structure exposes to environmental vibration of shafted propeller propulsion and engine vibration. The shipboard equipments are developed compliance to MIL-STD-167-1A. For this purpose, vibration fatigue life of shipboard equipment for long lives should be estimate via an analytical approach and vibration test. In this paper, High cycle fatigue strength of cast aluminum alloy A356 using shipboard equipment was evaluated by 14 S-N method. The stress applied on the structure is evaluated by an analytical method(frequency response analysis with sinusoidal input and a fatigue evaluation) to simulate a MIL-STD-167-1A test. The frequency with the maximum equivalent stress is shown by Max. test frequency and the vibration fatigue life of shipboard equipment was estimated by Miner’s rule.

회전익 항공기 진동흡수용 판스프링 개선연구

구정모(Jeong-Mo Koo),이광은(Gwang-Eun Lee),서정미(Jeong-Mi Seo),원태훈(Tae-Hoon Won) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.9

회전익 항공기는 블레이드 회전을 이용하여 양력을 발생시키기 때문에 진동의 영향에서 자유롭지 못하다. 이러한 진동을 줄이기 위하여, 승객실과 조종석 등에 진동흡수장치가 적용된다. 그 중 진동흡수용 판스프링은 조종석 하부에 장착되며, 조종사가 느끼는 진동을 줄여주는 역할을 한다. 본 연구에서는 회전익 항공기에서 발생한 판스프링 결함에 대한 원인을 분석하고 개선안을 제시하였다. 결함 원인 분석을 위하여, 구조해석과 파단면 분석을 진행하였으며, 결함원인은 피로수명 특성 저하로 나타났다. 기존 재질을 대체할 개선 재질 2가지의 적용사례 및 타당성을 분석하여 최종 개선안을 선정하였다. 최종 개선안은 GFRP(Glass Fiber Reinforced Plastics, 유리섬유 복합재)이며, 개선안 검증을 위한 시험을 수행하였다. 판스프링 구조물에 작용하는 공진을 모사하는 가진 시험기를 이용하여 피로시험을 진행하였다. 시험방법은 S-N 피로시험으로 진행되며, 평균 피로 수명 곡선(Mean Fatigue Curve)을 생성하여 수명을 비교하였다. 판스프링 내부 고체윤활제 재질 개선을 통하여 피로강도와 수명이 기존대비 1.5배 이상 증가함을 입증하였다. A rotorcraft is not free from the effects of vibration because it generates lift using the blade rotation which is a source of vibration. To reduce the vibrations in a rotorcraft, a vibration-absorbing device is used in the passenger compartment and cockpit. Among the various vibration-absorbing devices, the vibration-absorbing plate spring is widely used and installed in the lower part of the cockpit to reduce the vibration felt by the pilot. This study analyzed the causes of plate spring defects in rotorcraft and presented suggestions for improvement. To analyze the causes of the defects, structural and fracture surface analyses were performed, and the cause of the defect was found to be the deterioration of fatigue life characteristics of the spring material. The final improvement plan was obtained by analyzing various application cases and the feasibility of using two improved materials to replace the existing materials. The final improvement proposal is the use of GFRP (Glass Fiber Reinforced Plastics), and a test was performed to verify this proposal. A fatigue test was conducted using an excitation tester that simulates the resonance acting on the plate spring structure. This test method is an S-N fatigue test, and the lifespan was estimated and compared with that of the other materials by creating a Mean Fatigue Curve. It has been proven from this study that the fatigue strength and lifespan are increased by more than 1.5 times compared to the existing ones by the improvement of the solid lubricant material inside the plate spring.

The Impact Vibration-based Fatigue Damage Assessment of Steel and Steel Fiber Reinforced Concrete Composite Girder

Chen Xu,Saiji Fukada,Hiroshi Masuya 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.4

The steel-concrete composite girder has been usually applied in the civil structures. The current fatigue damage assessment on the composite girder, especially the negative bending region, mainly bases on the crack observation and deflection measurement. It is not stable sometimes, thus the impact vibration-based fatigue damage assessment was considered instead. A 3.3m steel-steel fiber reinforced concrete (SFRC) composite girder was designed and tested. The fatigue load, the impact load, and the static load were applied in the test. It showed that the local fatigue damage reflected by the tensile SFRC cracks may not be easily evaluated through observing the global mechanical change. However, the vibration modal parameters such as the vibration frequency, vibration mode, damping ratio might be useful for this. In particular, the vibration mode variation, which can be expressed by the Modal Assurance Criterion (MAC) value, may reflect the local fatigue damage on the composite girder.

전신진동운동(whole body vibration)이 근피로가 유도된 슬관절 고유수용성 위치감각기능에 미치는 영향

김성대(Kim, Sung-Dae),김만성(Kim, Man-Sung),김종오(Kim, Jong-Oh),이희혁(Lee, Hee-Huk),정일규(Jeong, Il-Gyu) 한국사회체육학회 2016 한국사회체육학회지 Vol.0 No.63

This study was designed to investigate the effect of whole body vibration(WBV) on the proprioceptive body position sense decline of knee joint induced by muscle fatigue. As the cross-over study, ten young college male students were assigned to WBV treatment group and control(complete rest) group with a week interval. Muscle fatigue was induced by knee flexion and extention exercise at 180˚/sec using isokinetic exercise machine(Biodex, USA). Muscle fatigue was determined at the time point when the torque conducted by each subject decreased to the 40% of one’s pre-determined maximal toque. The determination of proprioceptive body position sense was conducted twice(active, passive) at 55 of knee joint and the values of absolute error were measured before and after 10min-WBV or complete rest for each subject’s fatigued leg. The result was followed as this. 1) Muscle fatigue induced by isokinetic exercise reduced the proprioceptive position sense of knee joint(p<.05) 2) Whole body vibration exercise contributed to the recovery from the declination of proprioceptive position sense induced by muscle fatigue(p<.05) 3) Whole body vibration exercise contributed to the recovery from the declined maximal knee extension toque induced by muscle fatigue(p<.05)