• 정보저장시스템학회:학술대회논문집
• /
• 정보저장시스템학회 2005년도 추계학술대회 논문집
• /
• pp.210-214
• /
• 2005

The purpose of this paper is to study the effects of the flexibility of HDD base plates on spindle vibration via theoretical predictions and experimental measurements. The flexibility of the base plate can significantly affect HDD spindle vibration. This is the most prominent feature in 2.5 inch HDD. Nevertheless, theoretical analysis of the spindle vibration often neglects the flexibility of the non-rotating part including spindle, base plate, and top cover. Our theoretical model developed in University of Washington can include the flexibilities of spindle and base plate. As a result, our theoretical prediction generally agrees well with our experimental measurements in vibration analysis. Moreover, Because of its small form factor, industrial practice is to use flanged disks instead of regular disks in vibration testing of prototypes. Our experimental measurements indicate that flanged disks and regular disks have very different behavior when the frequency is above 1 KHz.

• 정보저장시스템학회논문집
• /
• 제2권2호
• /
• pp.111-116
• /
• 2006

The purpose of this paper is to study the effects of the flexibility of HDD base plates on spindle vibration via theoretical predictions and experimental measurements. The flexibility of the base plate can significantly affect HDD spindle vibration. This is the most prominent feature in 2.5 inch HDD. Nevertheless, theoretical analysis of the spindle vibration often neglects the flexibility of the non-rotating part including spindle, base plate, and top cover. Our theoretical model developed in University of Washington can include the flexibilities of spindle and base plate. As a result, our theoretical prediction generally agrees well with our experimental measurements in vibration analysis. Moreover, because of its small form factor, industrial practice is to use flanged disks instead of regular disks in vibration testing of prototypes. Our experimental measurements indicate that flanged disks and regular disks have very different behavior when the frequency is above 1 KHz.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
• /
• 제3권1호
• /
• pp.75-80
• /
• 1999

An investigation of noise and vibration caused by the reclamation of the foreshore around J village resulted in noise measurements of 56-84 dB at the first point, 62-81 dB at the second point, and 68-78 dB at the third point. These measurements were higher than the standard level of environmental noise that is 55 dB at noon and 45 dB at night. The vibration measurements were 61-83 dB at the first point, 63-88 dB at the second point, and 58-77 dB at the third point. These measurements were also higher than the standard level of environmental vibration that is 60 dB at noon and 54 dB at night. The measurements of scattering dust were 80 $\mu\textrm{g}$/$\textrm{m}^3$ at the first point, 120 $\mu\textrm{g}$/$\textrm{m}^3$ at the second point, and 169 $\mu\textrm{g}$/$\textrm{m}^3$ at the third point. These measurements were lower than the standard level of environmental dust that is 300 $\mu\textrm{g}$/$\textrm{m}^3$/day. Although the maximum vibration level was higher than the standard level of environmental vibration, it had no influence on the construction.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2010년도 춘계학술대회 논문집
• /
• pp.197-200
• /
• 2010

In some cases it is important to be able to measure not only the total sound intensity on a panel surface in a vehicle cabin, but also the components of that intensity due to sound radiation and due to absorption from the incident field. For example, these intensity components may be needed for calibration of energy flow models of the cabin noise. A robust method based on surface absorption coefficient measurement is presented in his paper.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2012년도 추계학술대회 논문집
• /
• pp.636-642
• /
• 2012

Delay-and-sum (DAS) Planar Beamforming has been a widely used Noise Source Identification Technique for the last decade. It is a quick one shot measurement technique being able to map sources that are larger than the array itself. The spatial resolution is proportional to distance between array and source, and inversely proportional to wavelength, thus the resolution is only good at medium to high frequencies. Improved algorithms using iterative de-convolution techniques offers up to ten times better resolution. The principle behind these techniques is described in this paper, as well as measurement examples from the automotive industry are presented.

• 소음진동
• /
• 제11권2호
• /
• pp.354-364
• /
• 2001

The vibration induced by high speed train running on rail is dealt with as an environmental problem. The train induced vibration is characterized by moving loads at specific frequencies and soil conditions. In fact, it is predicted that the vibration sources are involved the wheel distance, number of cars, speed of operation, drift of rails, structural born vibration, etc. In this paper the characteristics of transferring vibration induced by the high-speed train in operation is discussed. Field measurements was conducted at region from Chungnam Yungj So-jung-myan to Chungbuk Chungwon hyun-do-myun. In the near future. these data will be used as the fundamental data for establishment of the countermeasure for vibrational reduction of high speed train using the results of the field measurements and quantitative prediction of the vibration level

• Smart Structures and Systems
• /
• 제11권4호
• /
• pp.411-433
• /
• 2013

Due to its easy operation and wide applicability, the ambient vibration method is commonly adopted to determine the cable force by first identifying the cable frequencies from the vibration signals. With given vibration length and flexural rigidity, an analytical or empirical formula is then used with these cable frequencies to calculate the cable force. It is, however, usually difficult to decide the two required parameters, especially the vibration length due to uncertain boundary constraints. To tackle this problem, a new concept of combining the modal frequencies and mode shape ratios is fully explored in this study for developing an accurate method merely based on ambient vibration measurements. A simply supported beam model with an axial tension is adopted and the effective vibration length of cable is then independently determined based on the mode shape ratios identified from the synchronized measurements. With the effective vibration length obtained and the identified modal frequencies, the cable force and flexural rigidity can then be solved using simple linear regression techniques. The feasibility and accuracy of the proposed method is extensively verified with demonstrative numerical examples and actual applications to different cable-stayed bridges. Furthermore, several important issues in engineering practice such as the number of sensors and selection of modes are also thoroughly investigated.

• 화약ㆍ발파
• /
• 제29권2호
• /
• pp.43-50
• /
• 2011

본 연구에서는 발파가 이루어지는 공사현장에서의 거리별 진동레벨을 리온계측기로 측정하였고 같은 거리상에서 진동속도를 측정을 위해 BlastmateIII를 사용하였다. 현장실험에서 발파는 총 5,180kg의 장약량으로 총 130회의 발파가 진행되었으며 회당 발파공수는 5, 10, 20공으로 공당 4kg의 약량이 사용되었다. 발파로 인한 진동은 진동속도와 진동레벨로 같은 거리에서 동시 측정하였다. 계측은 발생원으로부터 15~102m 구간에서 측정하였고 8차례 구간을 나누어 진동속도, 진동레벨 데이터를 각각 273개 획득하였다. 측정된 진동속도 데이터를 이용하여 기존의 상관식에 의하여 분석하였으며 이를 실제 측정한 진동레벨과 비교 분석하고 상관성에 대하여 연구해 보았다.

• Structural Engineering and Mechanics
• /
• 제29권2호
• /
• pp.171-186
• /
• 2008

The seismic response analysis of an existing bridge needs a mathematical model that can be calibrated with measured dynamic characteristics. These characteristics are the periods and the associated mode shapes of vibration and the modal damping coefficients. This paper deals with the measurements and the interpretation of the results of ambient vibration tests done on a newly erected cable stayed bridge across the Oued Dib River at Mila city in Algeria. The signal analysis of ambient vibration records will permit to determine the dynamic characteristics of the bridge. On the other hand, a 3-D model of the bridge is developed in order to assess the frequencies and the associated modes of vibration. This information will be necessary in the planning of the test on the site (locations of the sensors, frequencies to be measured and the associated mode shapes of vibration). The frequencies predicted by the finite element model are compared with those measured during full-scale ambient vibration measurements of the bridge. In the same way, the modal damping coefficients obtained by the random decrement method are compared to those of similar bridges.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 춘계학술대회논문집
• /
• pp.550-555
• /
• 2007

This paper introduces the mechanical vibration-measurements of vibration on ships(ISO 20283). Regulations and guidelines for vibration of hull structures, propulsion machinery and onboard equipments on ship were established mainly by classification societies or International Association of Classification Societies(IACS). The initial draft of ISO 20283 was proposed by USA and based on US military standards. Though these are not suitable to passenger and merchant ships, many experts have felt the need of the ISO regulation for the vibration measurement on ship. Hence, these standards are re-drafted and reviewed by particulate ISO members. In this paper, authors introduce the important agendas and the controversial items during setup of ISO 20283.