• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.297-302
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• 2007

Vibrating test of vehicle component can be possible in lab-based simulators instead of field testing owing to the development of technology in control algorithm as well as computational process. Currently, Multi-Axial Simulation Table(MAST) is recommended as a vibrating equipment, which excites a target component for 3-directional translation and rotation motion simultaneously and hence, vibrational condition can be fully approximated to that of real road test. But, the vibration-free performance of target component is not guaranteed with MAST system, which is only simulator subjective to the operator. Rather, the reliability of multi-axial vibration test is dependent on the quality of input profile which should cover the required severity of vibrating condition on target component. In this paper, multi-axial vibration testing methodology of vehicle component is presented here, from data acquisition of vehicle accelerations to the obtaining the input profile of MAST using severe data at proving ground. To compare the severity of vibration condition, between real road test and proving ground one, energy principle of equivalent damage is proposed to calculate energy matrices of acceleration data and then, it is determined the optimal combination of special events on proving ground which is equivalent to real road test at the aspects of vibration fatigue using sequential searching optimal algorithm. To explain the vibration methodology clearly, seat and door component of vehicle are selected as a example.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.573-582
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• 1994

Blast vibration equations proposed previously are investigated. Special attention is given to the blast vibration equation which shows the best fitting to the geologic condition of Korea. The fittness of proposed blast vibration equation is analyzed and examined using many field data measured in Korea. The prediction of blast vibration equation using field data was performed by linear regression analysis. Moreover, after the prediction of each blast vibration equation, vibration velocity is recalculated on the basis of scaled distance at each equation. Reliability of regressioned blast vibration equation is observed by comparing predicted and measured velocity, which is divided into small-scale blasting of city and large-scale blasting of quarry. Based on this study, the best fitting equation to the Korean geologic condition is ROOT SCALING & CUBE ROOT SCALING proposed by USBM(United Nations Bureau of Mines). Also representative blast vibration equations depending on the different kinds of rock mass are proposed using measured and existing field data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.146-149
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• 2005

Thesedays, the reduction of hand-transmitted vibration of hand-held power tools is important issue for operators' welfare, In the study, frequency response function is measured and vibration total value is evaluated for solving the principle and effect of the BOSCH's vibration-proof handle. This handle functions as a dynamic damper and has the effect, 22% vibration total value reduction under idling condition using a system that consists of a PC with data acquisition system and LabVIEW program. The program in the system makes it possible to evaluate vibration total value according to ISO 5349. This handle offers a good example for figuring out the physical contradiction between the work efficiency and operators' health.

• Explosives and Blasting
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• v.29 no.2
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• pp.43-50
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• 2011

This study measured a vibration level at each distance of construction fields where blasts occur using Lion measuring instrument and used BlastmateIII to measure vibration velocity at the same distance. A total 130 blasts occurred with the weight of a total of 5,180 kg and the number of blast holes per blast was 5, 10 and 20. The weight of 4 kg was used for each hole. Vibrations caused by blast was measured at the distance with the same velocity and level. Measurements were carried 15~102 m away from the blast source. and 273 data on vibration velocity and level were obtained from eight measurements. It analysed data on vibration velocity measured based on existing correlation formulas and compared them to real measurements to analyse interrelationship.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.413-418
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• 2005

Vibration test using the MAST(Multi Axial Simulation Table) is more reliable test than conventional testing process focused on one directional vibration test. The former test could be possible with a advanced control algorithm and hardware supports so that most of the operation is automatically conducted by MAST system itself except the input information that is derived from the measured data. That means the reliability of the vibration test is highly depended on the input profile than any other cases before. In this paper, the optimal algorithm based on energy method is introduced so that the best combination of candidated input PSD data could be constructed. The optimal algorithm renders time information so that the vibration fatigue test is completely possible for any measured signals one wants. The real road test is conducted in short intervals containing some rough roads and the candidated input PSD is obtained from the extra road in proving ground. The testing is targeted for the electronically operated door and seat.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.901-904
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• 2007

The power flow analysis (PFA) can be effectively used to predict structural vibration in medium-to-high frequency ranges. In this paper, vibration experiments have been performed to observe the analytical characteristics of the power flow analysis of the vibration of various coupled plates. Those plates include two plates coupled with angles of $90^{\circ}$\;and\;30^{\circ}$, respectively. In the experiment, the loss factor and the input mobility at a source point on each coupled plate have been measured. The data for the loss factors have been used as the input data to predict the vibration of the coupled plates with PFA. The frequency response functions have been measured over the surface of the coupled plates. The comparison between the experimental results and the predicted PFA results for the frequency response functions has been performed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.3
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• pp.313-319
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• 2009

The blasting has a lot of economic efficiency and speediness but it can damage to a neighbor structure, a domestic animal and a cultured fish due to the blasting vibration, then the public grievance is increased. Therefore, we need to manage the blasting vibration efficiently. The prediction of the correct vibration velocity is not easy because there are lots of different kinds of the scale of blasting vibration and it has a number of a variable effect. So we figure the optimum line through the least-squares regression by using the vibration data measured in hard rock blasting and compared with the design vibration prediction equation. As a result, we confirm that the vibration estimated in this paper is bigger than the design vibration prediction equation in the same charge and distance. If there is a Gaussian normal distribution data on the left-right side of the least squares regression, then we can estimate the vibration prediction equation on reliability 50%(${\beta}=0$), 90%(${\beta}=1.28$), 95%(${\beta}=1.64$). 99.9%(${\beta}=3.09$). As a result, it appears to be suitable that the reliability is 99% at the transverse component, the reliability 95% is at the vertical component, the reliability 90% is at the longitudinal component and the reliability is 95% at the peak vector sum component.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.10
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• pp.932-939
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• 2012

Recently, data centers are being established because IT and telecommunication industries are growing. The data centers have to install emergency generators to prevent unexpected shutdown of the electrical power supply. When the data centers are located in the densely populated urban area, the operating noise of the emergency generators can be a cause of people's complaints. In this case, it is necessary to establish effective countermeasure by noise & vibration specialists. To achieve this, noise reduction measure using noise measurement data and 3D noise analysis method have been employed in this study.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.8 s.113
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• pp.806-813
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• 2006

An important factor of vibration test using MAST(multi axial simulation table) system is the reliance of input excitation source. Generally the generation of input excitation source is obtained by the measured data on special road in proving ground. The measured data on special road have more exciting energy than the data of real fields, therefore the time and expense for test can be reduced. But the magnitude of input excitation source must be defined by comparison with the excited energy on real field. The object of this paper makes the data base of domestic roads for the definition of input excitation source which is obtained by the measured data on special road in proving ground. These real field data on domestic roads are analyzed by the power spectral density and interrelationship index.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.183-193
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• 1999

In the previous study, a module-type vibration analysis system using modular approach is developed for the purpose of analyzing the torsional vibration of vehicle driveline. In the present paper, the system is utilized to investigate the torsional vibration of the driveline of a middle duty truck. The driveline with driving condition is modeled and the torsional vibration response is simulated. The resonance 45Hz is found at engine speed 900rpm and the resultant vibration is very high. It shows favorable agreements with reference data. The effects of parameter change on torsional vibration are also investigated, so it is clarified that clutch characteristics, axle shaft stiffness are very influential on reduction of vibratio. So the countermeasure is proposed for the clutch characteristics. The reduction of torsonal vibration by 8rad/sec is obtained.