휠체어 이용자의 안전성 향상을 위한 보도 평탄성 측정 방법 개발

김지호,오흥운 한국도로학회 2020 한국도로학회논문집 Vol.22 No.5

PURPOSES : In this study, the flatness of a sidewalk surface was evaluated by measuring the vibration acceleration experienced by wheelchair users passing the sidewalk using a walking measure. The objective of this study is to derive a linear equation for converting the vibration acceleration of a sidewalk surface measured using a walking measure into vibration acceleration of a wheelchair. METHODS : To this end, field measurements were obtained. Twenty sites with different sidewalk surface materials were selected to measure the vibration accelerations of the walking measure and wheelchair. A regression analysis was conducted with the measured root mean square value of the vibration acceleration, and a linear equation expressing the walking measure and wheelchair vibration acceleration was derived. RESULTS : The regression analysis was conducted by inputting the vibration acceleration of the wheelchair into the Y-axis and that of the walking measure into the X-axis. Thus, a linear equation between the walking measure and wheelchair acceleration could be derived. Further, linear equations could be derived and applied based on the situation using various standard walking measures and wheelchairs. These equations could be used to convert the vibration acceleration of the walking measure into that of the wheelchair. Substituting the converted vibration acceleration into the comfort level specified in ISO 2631-1 was expected to indicate the flatness of the sidewalk. CONCLUSIONS : This study confirmed that a linear equation for the two vibration accelerations could be derived by measuring the vibration accelerations of the walking measure and wheelchairs of 20 different sites. The vibration acceleration measured using the walking measure could be converted into that of the wheelchair using this linear equation. In addition, the flatness of the sidewalk could be evaluated by measuring the vibration acceleration of the walking measure using this linear equation.

Accuracy and noise analyses of 3D vibration measurements using laser Doppler vibrometer

Khalil, H.,Kim, D.,Nam, J.,Park, K. ELSEVIER 2016 MEASUREMENT -LONDON- Vol.94 No.-

The in-plane and out-of-plane vibration components are used for 3D vibration measurements. The latter can be calculated by using three laser scanning vibrometers (LSVs) or by moving a single LSV to three different locations. These vibration components are calculated from the vibration signals measured at each of the three locations and the angles between the local coordinates and the LSV locations. The accuracy of the in-plane and out-of-plane vibration components can be degraded depending on the measurement angle. In addition to accuracy, the noise contained in the LSV can be amplified depending on the measurement angle. Hence, it is necessary to implement an analysis methodology for the angles, which is conducted for 2D vibration measurements first before extended to 3D. Finally, experiments are performed for both 2D and 3D at small and appropriate angles, and the elicited results are compared to those elicited using a 3D accelerometer.

Two-dimensional tool tip vibration measurement method with mirror optical fiber bundles in milling machines

Binghui Jia 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5

Tool vibration has great potential harm to the stability and machining accuracy of machine tools. Since the tool tip is in direct contact with the workpiece, as the input and key link to obtain the frequency response function of the tool-spindle system, it is the most direct and important characterization of cutting vibration. In this paper, a method with mirror optical fiber bundles is presented for two-dimensional tool tip vibration measurement. It enables in situ, simultaneous laterally and longitudinally vibration displacement measurement directly without contact to the tool. To validation of the measurement system, a static calibration platform is built, the experiment results show: the laterally and longitudinally linear measurement range of the fiber bundles are 500 µm and 300 µm, respectively, with a measurement accuracy of 1 %. The dynamic characteristic of the measurement system is evaluated depending on tool tip vibration measurement in the machine start-stop process, as well.

대구경 반사경 광학측정용 타워의 진동에 의한 광학측정오차 분석

강필성,김옥관,안희경,양호순 한국광학회 2017 한국광학회지 Vol.28 No.6

In the present research, the optical measurement error induced by vibration of the optical measurement tower for large mirrors at KRISS(Korea Research Institute of Standards and Science) is investigated. The vibrations of the tower structure, the interferometer, and the nulllens are measured while the surface errors of the 600-mm-diameter on-axis aspheric mirror are measuring, under various environmentalconditions. The increase of surface error induced by alignment error with respect to vibration is analyzed. As a result, the interferometerand the null lens, which are located on the top of the tower, are highly sensitive to vibration. Additionally, the surface error of the mirroris strongly increased when the vibration directions of the interferometer and the null lens are different. To reduce the alignment error andthe surface error induced by vibration, the tower structure should be improved, to be insensitive to low-frequency vibration. Alternatively,optical measuring under stable conditions by vibration monitoring can improve the reliability of the surface error measurement.

A Study on the Reduction of Uncertainty in the Measurement of Power Tool Vibration

Seok-Hyun Choi,Han-Kee Jang,Tae-Won Park 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.2

To increase accurateness and reliability of the evaluation of power tool vibration transmitted to an operator, it is necessary to measure the grip and feed forces during the measurement of hand-transmitted vibration. In the study a system was invented to measure the vibration and the grip and/or feed force, which consists ofa measurement handle and a PC with a data acquisition system and the corresponding software. Strain gages and an accelerometer were mounted on the handle surface for the simultaneous measurement of the forces and the vibration. The program in the system makes it possible to monitor the grip and feed force during the tool operation so that the operator keeps the applying forces within the pre-determined range. Investigating the vibration total values, frequency-weighted root-mean-square accelerations at the handle, obtained in repetition for each power tool with control of the grip and feed force showed more consistency than those measured without force control. By using the system the experimenter can reduce uncertainty in measurement of hand-held power tool vibration.

A fast high-resolution vibration measurement method based on vision technology for structures

Son, Ki-Sung,Jeon, Hyeong-Seop,Chae, Gyung-Sun,Park, Jae-Seok,Kim, Se-Oh Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.1

Various types of sensors are used at industrial sites to measure vibration. With the increase in the diversity of vibration measurement methods, vibration monitoring methods using camera equipment have recently been introduced. However, owing to the physical limitations of the hardware, the measurement resolution is lower than that of conventional sensors, and real-time processing is difficult because of extensive image processing. As a result, most such methods in practice only monitor status trends. To address these disadvantages, a high-resolution vibration measurement method using image analysis of the edge region of the structure has been reported. While this method exhibits higher resolution than the existing vibration measurement technique using a camera, it requires significant amount of computation. In this study, a method is proposed for rapidly processing considerable amount of image data acquired from vision equipment, and measuring the vibration of structures with high resolution. The method is then verified through experiments. It was shown that the proposed method can fast measure vibrations of structures remotely.

선박 시운전용 모바일 기기 기반 진동 측정 시스템 개발

엄성민,나웅재,선경호,박정희,조혜영,남대호,오환엽,신윤호 한국비파괴검사학회 2023 한국비파괴검사학회지 Vol.43 No.2

Measuring vibrations on a ship is difficult under environments such as high-altitude areas, confined spaces, and remote locations from the target equipment or structure. Therefore, a more convenient, simple, and reliable measurement system has been requested by field engineers and ship trial teams. To this end, a mobile device based vibration measurement system for ships is proposed in this paper to alleviate this problem and provide a better measurement environment. This includes a vibration extraction algorithm and a signal processing technique that employs a movie clip for the target system. Among the various image processing techniques, a phase-based template matching method is selected and applied, which is advantageous for vibration measurement, and a measurement procedure using mobile device is suggested by recording the movie clip to perform post-signal processing. The proposed system is developed using an android operating-system-based software and its effectiveness is verified using actual vibration measurements. 선박 시운전 시 가속도계를 활용한 진동 측정은 고소 구역 및 협소한 공간의 측정이나, 대상 장비 혹은 구조물이 상대적으로 멀리 위치한 조건에서 시간 소요가 많이 되거나 위험한 작업이 될 수 있다. 따라서 보다 간편하고 신뢰할 수 있는 측정 시스템에 대한 현장 관리자 또는 시운전 팀의 요구는 선박이 대형화됨에 따라 지속적으로 증가하고 있다. 본 연구에서는 이러한 문제점을 완화하고 보다 나은 측정 환경을 제공하기 위해 모바일 기기 기반으로 대상 장비에 대해 촬영된 동영상을 통한 진동 추출 알고리즘 및 신호 처리 방법론에 대해 제안하고자 한다. 다양한 영상 처리 기술 중 진동 측정에 유리한 위상 기반 템플릿 매칭 방법을 선택하여 적용하고 이를 모바일 기기에서 측정-처리-전시할 수 있는 전용 앱을 개발하는 과정을 소개하고자 한다. 제안된 측정 시스템은 안드로이드 운영체제 기반의 모바일 기기를 활용하여 구현하였으며, 실제 진동 측정 및 고찰을 통해 그 신뢰성을 검증하였다.

카메라 영상을 이용한 진동변위 측정

손기성(Ki-Sung Son),전형섭(Hyeong-Seop Jeon),박진호(Jin-Ho Park),박종원(Jong Won Park) 한국소음진동공학회 2013 한국소음진동공학회 논문집 Vol.23 No.9

Vibration measurements using image processing have been studied by many researchers as it can remotely measure vibration displacements at multiple points simultaneously. It is difficult, however, to obtain accurate displacement from the measured image signals because the resolution of image data is dependent on camera performance and normally lower than that of vibration transducer directly measured. This paper suggests the enhanced technique for vibration displacement measurement by applying the expected value of edge probability distribution to the varying pixel points in the image. The method can both increase the resolution limit of camera image and decrease the measurement errors. The working performance of the proposed technique is verified applying to the vibration measurement of a rotating machine.

경남 창원시 진해 지역의 발파진동 예측에 관한 연구

이충원(Lee, Chung-Won) 한국방재학회 2017 한국방재학회논문집 Vol.17 No.4

국가기반시설의 확충을 위한 발파 등 각종 건설공사에 기인한 진동 문제는 민원에 의해 그 중요성이 점증하고 있는 실정이다. 진동은 대표적인 환경피해 요인으로, 건설방재적 관점에서도 대단히 큰 의미를 갖는다. 본 연구에서는 경남 창원시 진해 지역에서 실규모 시험발파를 수행하여 심발발파 종류에 따른 파쇄암의 입경을 분석하고, 이에 대한 진동 계측 결과를 통해 신뢰수준 95%의 자승근식을 발파진동 추정식으로 제안하였다. 실규모 시험발파 결과와 비교시, 거리에 따른 발파진동 추정치는 미 광무국 식이 실규모 시험발파 결과보다 보수적인 것으로 확인되었다. 따라서, 현장 여건을 고려한 최적의 발파설계를 위해서는 실규모 시험발파를 통한 진동의 계측 및 이에 근거한 발파진동 추정식을 도출할 필요가 있다. 그러나, 터널 굴착 등의 실제 발파시에는 진동을 함께 계측함으로써 주변의 보안물건에 피해가 발생하지 않도록 유념하여야 할 것이다. Vibration problems due to a number of construction works including blasting for infrastructure development are getting important because of a civil appeal. Vibration is representative factor of environmental damage, hence, this has great meaning to prevent potential disasters. In this study, through the real-scale test blasting performed at Jinhae area, Changwon, Gyeongnam, the diameter of blasted rock was analyzed with blasting method, and square root equation(SRE) with 95% confidence level was proposed for prediction of blasting-induced vibration. From the comparison between tendencies of blasting-induced vibration with distance, it was confirmed that the predicted blasting-induced vibration by USBM(U.S. Department of Interior, Bureau of Mines) equation was more conservative than that by proposed equation based on the real-scale test blasting. Therefore, measuring vibration and determining equation for prediction of blasting-induced vibration through the real-scale test blasting are needed for optimal blast design considering field condition. However, in the case of real blasting including tunnel excavation, measuring vibration is required for damage prevention to surrounding facilities.

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>