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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Society of Information Storage Systems
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The Society of Information Storage Systems
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Volume 5, Issue 2 - Sep 2009
Volume 5, Issue 1 - Mar 2009
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Design of a Slim-Type Auto-Focusing Module with a Cam Structure
Kim, Kyung-Ho ; Lee, Seung-Yop ; Shin, Bu-Hyun ; Kim, Soo-Kyung ;
Transactions of the Society of Information Storage Systems, volume 5, issue 1, 2009, Pages 1~7
Recently, the growing market demand for small and slim mobile phone cameras requires the size reduction of the camera module. In this paper, an auto-focusing actuator for camera phones is proposed by converting the rotational motion by a rotary VCM actuator into the linear motion using a novel cam structure. This new concept for auto-focusing module enables the reduction of the module thickness and low power consumption. This paper presents the theoretical analysis and optimal design for VCM actuator, cam structure and preload spring. Finally, the experimental results using a prototype with the size of
are compared with the theoretical predictions.
Development of OIS actuator for Mobile Phone Camera
Baek, Hyun-Woo ; Hur, Young-Jun ; Song, Myeong-Gyu ; Park, No-Cheol ; Park,, Young-Pil ; Park, Kyoung-Su ; Lim, Soo-Cheol ; Park, Jae-Hyuk ;
Transactions of the Society of Information Storage Systems, volume 5, issue 1, 2009, Pages 8~13
In this study, to compensate trembling of camera caused by vibration of user's hand, 2-axis voice coil actuator of optical image stabilizer (OIS) is suggested. In consideration of actuating performance, volume of OIS and application of hall sensor, one of concept models is selected and it is optimized to maximize the actuating performance. Two types of mechanisms that have the feasibility of moving in 2-axis and the capability of including the optimized EM circuit are proposed. Finally both types are fabricated and then actuating performance of OIS actuator and behavior of hall sensor are verified through the experiment.
Dynamic Characteristic Improvement of the Plate Spring in a 2-axis Small Sized Actuator
Park, Soon-Ok ; Yoo, Jeong-Hoon ; Park, No-Cheol ;
Transactions of the Society of Information Storage Systems, volume 5, issue 1, 2009, Pages 14~18
This paper proposed an optimal plate spring design for the optical image stabilizer in mobile phones. The voice-coil motor (VCM) with plate spring is the smallest, lowest-cost solution for auto focus on the market today and it is also the simplest to implement. The VCM is selected in this paper for auto focusing. However, the design process is complex due to the many design variables coupled to each other and some constraints of each directional motion caused by the characteristics of plate spring. Because of the complex formulation of the design objective, a plate spring design is proposed through the design of experiments to find the optimal design satisfying design constraints.
Experimental and Numerical Study on an Air-Stabilized Flexible Disk Rotating Close to a Rigid Rotating Disk
Gad, Abdelrasoul M.M. ; Rhim, Yoon-Chul ;
Transactions of the Society of Information Storage Systems, volume 5, issue 1, 2009, Pages 19~35
The present work is an experimental and analytical study on a flexible disk rotating close to a rigid rotating disk in open air. In the analytical study, the air flow in the gap between the flexible disk and the rigid disk is modeled using Navier-Stokes and continuity equations while the flexible disk is modeled using the linear plate theory. The flow equations are discretized using the cell centered finite volume method (FVM) and solved numerically with semi-implicit pressure-linked equations (SIMPLE algorithm). The spatial terms in the disk equation are discretized using the finite difference method (FDM) and the time integration is performed using fourth-order Runge-Kutta method. An experimental test-rig is designed to investigate the dynamics of the flexible disk when rotating close to a co-rotating, a counter-rotating and a fixed rigid disk, which works as a stabilizer. The effects of rotational speed, initial gap height and inlet-hole radius on the flexible disk displacement and its vibration amplitude are investigated experimentally for the different types of stabilizer. Finally, the analytical and experimental results are compared.
Experimental realization of an imaging system using wavefront coding in mobile phone camera
Kim, Jong-Pil ; Lee, Sang-Hyuck ; Park, No-Cheol ; Park, Young-Pil ; Park, Kyoung-Su ;
Transactions of the Society of Information Storage Systems, volume 5, issue 1, 2009, Pages 36~40
We describe the experimental realization of image system using wavefront coding in 3-Mega pixel mobile phone camera. We designed aspheric lens to extend the depth of field (DOF) using wavefront coding. In addition, through the aspheric lens and lens barrel manufacturing, we obtained a raw image from a camera module. In our method, the acquired images are restored in the spatial frequency domain using the proposed filter and the spatial frequency response (SFR) is calculated. The proposed filters are composed of image denoising filter using low band pass filter in frequency domain and restoration filter for image restoration. Finally, we achieve an enhanced image by super-resolution image processing. Visual examples are given to demonstrate the performance of the proposed filter.
Air-Gap Control Using Optimal PID Controller for SIL-Based Near-Field Recording System
Shin, Won-Ho ; Kim, Jung-Gon ; Park, No-Cheol ; Yang,, Hyun-Seok ; Park, Young-Pil ; Park, Kyoung-Su ;
Transactions of the Society of Information Storage Systems, volume 5, issue 1, 2009, Pages 41~46
In SIL-based NFR servo systems, the residual error and the overshoot that are occurred in the process of the modes-witching servo which consists of approach, gap-control modes, and safety mode are reduced by using PID controller. However, the design method of conventional PID controller is not sufficient for the stable air gap control system. Therefore, the optimal PID controller using LQR manner is more useful to find the designed parameters of PID controller. In this paper, we show that the performance of the optimal PID controller is better than that of the lead-lag controller.
A study on suspension state matrix to improve load/unload performance
Lee, Yong-Hyun ; Kim, Ki-Hoon ; Kim, Seok-Hwan ; Park, No-Cheol ; Park, Young-Pil ; Park, Kyoung-Su ; Kim, Cheol-Soon ;
Transactions of the Society of Information Storage Systems, volume 5, issue 1, 2009, Pages 47~52
Most hard disk drives that apply the ramp load/unload technology unload the heads at the outer edge of the disk while the disk is rotating. The load/unload includes the benefits as like an increased areal density, a reduced power consumption and an improved shock resistance. A lot of papers investigating the effects of the various load/unload parameters such as a suspension tab, a limiter, a ramp and air-bearing surface designs have been published. However, in previous researches, an effect of the suspension is not considered at each load/unload step. In this paper, we focus that a variation of the state matrix affects the load/unload performance on based on a state matrix that is a stiffness matrix of the suspension. Because the state matrix is related to the suspension at each load/unload step, to change the state matrix means the structural change of the suspension. Therefore, we investigated a range of a pitch static attitude(PSA) and a roll static attitude(RSA) for load/unload performance. We also analyzed an effect of the variation of the state matrix a range of load/unload velocity occurred a slider-disk contact. We determined the variation of the state matrix to improve the load/unload performance through comparison of each factor of state matrix.