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박경수(Park, Kyoung-Su),박노철(Park, No-Cheol),양현석(Yang, Hyun-Seok),박영필(Park, Young-Pil),이용현(Lee, Yong-Hyun) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.11
L/UL(Load/unload) mechanism has been widely used in SFF(Small form factor) HDD because L/UL technology has many advantages such as an increase of areal density, reduction of power consumption and improvement of shock resistance. In this system, the most important design goal is no slider-disk contact and fast air-hearing breaking during L/UL process. To do so, we should consider many design parameters related to L/UL system. The ramp shape is the most dominant component among parameters which dramatically affect the L/UL performance. This paper makes an advanced ramp model using ANSYS/LS-DYNA. Through this FE model, this paper investigates the effect of initial ramp slope and location of air-bearing breaking. From the experiment for three different ramps, we also verify that experimental results agree with simulation results. We conclude that the ramp design should have small ramp slope at the moment which a suspension tap contacts with ramp and large ramp slope after air-bearing breaking in order to improve L/UL Performance.
MLCC 에 의해 기판에서 발생하는 소음 분석 및 예측
박노철(No-Cheol Park),김동준(Dong-Joon Kim),고병한(Byung-Han Ko),박영필(Young-Pil Park),박흥길(Heung-Kil Park) 한국소음진동공학회 2014 한국소음진동공학회 학술대회논문집 Vol.2014 No.10
MLCC is one of the most frequently used component in high-tech device like smart phone. Because of dynamic characteristic of piezoelectric materials which is main ingredient of MLCC, its vibration leads to acoustic noise from pcb. To solve this problem at minimal cost, company has to change only the main noise-generating MLCC to low noise-generating MLCC. To find the main noise source, this study approached to solution from a vibration point of view. From mode shapes of pcb at particular frequencies, two groups can be obtained; MLCCs soldered at where maximum deformation occurs and where anti-phase with respect to the other group appears. When the MLCC belongs to 1st group does not working, amplitude at where maximum deformation occurs decreases compared to when all MLCCs are working. This tendency also appears in noise measurement. This analysis can be put to use in various fields where require noise reduction or noise source identification.