• Transactions of the Society of Information Storage Systems
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• v.6 no.2
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• pp.57-62
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• 2010

This paper measured and analyzed the source of total power loss of an ODD of a notebook computer. It shows that the biggest power loss is the windage loss due to the friction between rotating disk and surrounding air. It measured the power loss by the tilting motion of a rotating disc which is originated from the unbalanced mass of the rotating disc or the squareness between case-rotor and shaft. The power loss of rotating disc due to tilting motion was also calculated by using FLUENT, and it was correlated with the measured one. This paper shows that the one of the effective methods to reduce the power loss of an ODD is to reduce the tilting motion of a rotating disc.

• Transactions of the Society of Information Storage Systems
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• v.2 no.1
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• pp.56-64
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• 2006

This paper proposes a new and simple input prediction method for robust servo system. A robust tracking control system for optical disk drives to reject disk runout was recently proposed based on both Coprime Factorization(CF) and Zero Phase Error Tracking(ZPET) control. The CF control system can be designed simply and systematically. Moreover, this system has not only stability but also robustness to parameter uncertainties and disturbance rejection capability. Since optical disk tracking servo systems can detect only racking error, it was proposed that the reference input signal for ZPET could be estimated from tracking errors. In this paper, we propose a new control structure for the ZPET controller. It requires less memory than the previously proposed method for the reference signal generation. Therefore, it is very effective in runout control. Furthermore, this method can be applied to defective optical disk like surface defects on disk. Numerical simulation and experimental result show the proposed method effective.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.2
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• pp.135-142
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• 2005

This paper presents an adaptive repetitive control scheme for optical disk drives to track a variable periodic reference signal. Periodic disturbances can be adequately attenuated using the concept of repetitive control, provided the period is known. Because optical disk drives support various speeds, they have the varying periodic disturbances. Based on repetitive control to change sampling frequency to follow the change of reference period, an adaptive repetitive control is proposed in order to deal with such disturbances. The proposed control consists of the repetitive controller and the frequency generator. The former uses a varying sampler operating at fixed multiple times of the disturbance frequency and the latter generates the changeable sampling frequency based on the disturbance frequency. The experimental results on the control of an optical disk drive demonstrate the effectiveness of the proposed schemes and the improvement of random access time as well.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.811-819
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• 2017

A behavior pattern analysis algorithm based on descriptors consists of information of a moving object and temporal histogram is proposed. Background learning is performed first for detecting, tracking and analyzing moving objects. Each object is identified using an association of the center of gravity of objects and tracked individually. A temporal histogram represents a motion pattern using positions of the center of gravity and time stamp of objects. The characteristic and behavior of objects are figured out by comparing each coordinates of a position history in the histogram. Behavior information which is comprised with numbers of a start and end frame, and coordinates of positions of objects is stored and managed in the linked list. Descriptors are made with the stored information and the video retrieval algorithm is designed. We confirmed the higher retrieval accuracy compare with conventional methods.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.111-122
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• 2009

Dissolution of some of geo-materials may yield the loss of the soil strength and the settlement of earth structures. The goal of this study is to monitor the several physical behaviors of soluble mixtures during dissolution. Sand-salt mixtures are used to monitor the meso to macro response including the settlements and shear waves. The mixtures of photoelastic and ice disks are used to monitor micro to meso behavior of soluble mixture including the void ratio, force chain, coordination number and horizontal force changes. In the sand-salt mixtures, shear waves are measured by using bender elements in conventional oedometer cells. In the photoelastic disk - ice disk mixtures, micro to meso response are measured by digital images and load cells. The shear wave velocity decreases at the initial stage of the dissolution, and then increases and approaches to asymptotic value. The larger dissoluble particle and the more random packing produces the severe horizontal fore change. After dissolution, the void increases and the coordination number decreases. This study demonstrates that the particle level behavior such as the changes of the force chain, void ratio, and coordination number affects the global behavior such as the change of the shear wave velocity and horizontal force of the system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.538-539
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• 2010

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.414-416
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• 2008

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.507-508
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• 2008

• The Optical Journal
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• s.122
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• pp.20-21
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• 2009

본 통계는 2002년 1월부터 디아조(Diazo) 광디스크 파일링, 타이프 라이터, 2005년 1월부터 서류분쇄기(Shredder), 타임레코더(Time recorder)가 생산 통계에서 제외되었기 때문에 전체의 숫자에는 포함되어 있지 않다. 지면 사정상 오프셋인쇄기(생산수 출입)과 워드프로세서(수출입)의 표는 생략했지만, 사무기 전체의 숫자에는 포함되어 있다. 그리고 2007년부터 회계기(수출입)가 통계에서 제외되어 전체 숫자에는 들어있지 않다. 한편, 2007년 1월 통계부터 수출입의 복사기 카테고리가 변경되어, 지금까지 계산하지 않았던 레이저복합기(FAX, 프린터, 스캐너 기능을 탑재한 기종)를 통계에 넣었기 때문에 숫자가 종전보다 늘어났으며 정전간접식, 기타 분류는 없어졌다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.71-74
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• 1996

본 연구에서는 반복 학습제어 이론을 기초로 하는 하이브리드 신경망 제어기를 제안한다. 신경망으로는 백프로퍼게이션(backpropagation) 신경망을 사용하고, 기존의 반복 학습 제어 이론의 단점을 보안한 제어 알고리즘을 제안한다. 백프로퍼게이션 신경망의 맵핑(mapping)의 특징으로 원하는 목표 패턴에 추종할 수 있는 출력 패턴을 생성하고 반복 학습에 소요되는 학습시간을 줄일 수 있다. 실험결과에서 보듯이 제안된 제어 알고리즘은 목표패턴에 수렴함을 알 수 있다. 제시한 알고리즘은 CD-ROM 드라이브와 같은 광디스크 드라이브류의 초점 제어 등에 응용할 수 있다.