Seong-Woo Kang

The acoustic noise characteristics of HDD due to the structural excitation of spindle motor

HDD structure is excited by the dynamic motion of disk-spindle motor components. Those excitations which are generated from stator, magnet rotor, bearings and disks, are transmitted through motor spindle and flange to HDD cover and base. The operational deflection shape measurement can show the structural elicitation patterns at the most influential frequency of the acoustic noise level. One of those components is the axial excitation along spindle, and the other is the local orbital excitation at the contact area of motor flange and base. In order to make a reduction of those structural transmission excitations, the structure of spindle motor should be modified to the direction of reinforcement at transmission path. Some excitation of spindle motor component carrying out essential function is unavoidable. So it is the efficient may of HDD noise improvement to control the structural transmission of excitation.

Identification of shock characteristics in hard disk drive by using time-frequency signal processing technique

A transient signal processing technique using Wigner distribution (WD) is applied to identify the dynamic characteristics when a disk drive system is subject to external shock vibration. It is shown that the smoothed WD technique essentially reveals the propagating characteristics of shock vibration on the specified position of disk drive system as well as head-slap and lift-off phenomena. A parametric investigation for the shock spectrum of suspension is also presented to provide a useful guideline for the shock-resistant disk drive design.

Noise source identification of hard disk drive using sound intensity and its control

Sound intensity technique and ODS (Operational Deflection Shape) technique are applied to identify the acoustic noise source of a hard disk drive system. The sound intensity is used to visualize the exact locations of noise sources, and the ODS to visualize the vibration pattern and to obtain the dynamic characteristics of the noise sources. Based on the visual information on the noise source location and its dynamic characteristic, the optimum structural modification and sound absorption are designed to modify the dynamics of the acoustic noise and to suppress the acoustic radiation power from the disk drive system.