• 정보저장시스템학회논문집
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• 제1권2호
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• pp.115-120
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• 2005

As a popularity of a portable digital device such as a cellular phone, a digital camera and a MP3 player is spreading, the demand of the mobile storage device increases rapidly. A bluray technology using 405nm laser diode and objective lens having high NA(Numerical Aperture), 0.85, satisfies a miniaturization and a high capacity which are the requirements of the portable device. To develop SFFOP(small form factor optical pickup), it is prerequisite to minimize the number of optical components and establish evaluation and assembly method of micro optical pickup system as well as mass production method of micro optical component. To minimize optical elements of optical pickup, there have been many researches to use P-HOE(Polarized Holographic Optical Element) due to its extremely small size and versatile function. However, P-HOE is handled and assembled very accurately in SFFOP. In this paper, static error signal detection method is developed for an alignment of P-HOE in SFFOP. Using developed static error signal detection method, P-HOE can be aligned very accurately with real time result of static error signals of pickup such as FES(focusing error signal) and TES(Tracking Error Signal). The developed static error signal detection method is verified by the evaluation of commercialized DVD Pickup. And finally. developed static error signal detection method is applied for the assembly of P-HOE in SFFOP system satisfies specification of BD(Blu-ray Disk).

• Progress in Superconductivity
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• 제9권1호
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• pp.23-28
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• 2007

In order to have a superconductive connection between the wire-wound pickup coil and input coil, typically Nb terminal blocks with screw holes are used. Since this connection structure occupies large volume, large stray pickup area can be generated which can pickup external noise fields. Thus, SQUID and connection block are shielded inside a superconducting tube, and this SQUID module is located at some distance from the distal coil of the gradiometer to minimize the distortion or imbalance of uniform background field due to the superconducting module. To operate this conventional SQUID module, we need a higher liquid He level, resulting in shorter refill interval. To make the fabrication of gradiometers simpler and refill interval longer, we developed a novel method of connecting the pickup coil into the input coil. Gradiometer coil wound of 0.125-mm diameter NbTi wires were glued close to the input coil pads of SQUID. The superconductive connection was made using an ultrasonic bonding of annealed 0.025-mm diameter Nb wires, bonded directly on the surface of NbTi wires where insulation layer was stripped out. The reliability of the superconductive bonding was good enough to sustain several thermal cycling. The stray pickup area due to this connection structure is about $0.1\;mm^2$, much smaller than the typical stray pickup area using the conventional screw block method. By using this compact connection structure, the position of the SQUID sensor is only about 20-30 mm from the distal coil of the gradiometer. Based on this compact module, we fabricated a magnetocardiography system having 61 first-order axial gradiometers, and measured MCG signals. The gradiometers have a coil diameter of 20 mm, and the baseline is 70 mm. The 61 axial gradiometer bobbins were distributed in a hexagonal lattice structure with a sensor interval of 26 mm, measuring $dB_z/dz$ component of magnetocardiography signals.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1522-1526
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• 2005

In this study, the fabrication of large area silicon mirror is accomplished by anisotropic etching using MEMS for implementation of integrated optical pickup and the process condition is also established for improving the mirror surface roughness. Until now, few results have been reported about the production of highly stepped $9.74^{\circ}$ off-axis-cut silicon wafer using wet etching. In addition rough surface of the mirror is achieved in case of long etching time. Hence a novel method called magnetorheolocal finishing is introduced to enhancing the surface quality of the mirror plane. Finally, areal peak to valley surface roughness of mirror plane is reduced about 100nm in large area of $mm^2$ and it is applicable to optical pickup using infrared wavelength.

• 대한기계학회논문집B
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• 제22권12호
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• pp.1702-1714
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• 1998

Removal of spilled oil over the sea and the river has become one of the urgent problems in these days. Removing oil using mechanical devices was recommended because chemical dispersion could cause the secondary contamination in the environment. In the present study a series of experiments were carried out to study the effect of operating conditions, especially, the angle between the belt and the fluid surface on the rate of recovery for the spilled oil using a belt skimmer. Three different types of operation, namely, upward pickup, downward pickup and up-and-downward pickup situations have been investigated for various contact angles, belt speeds and oil thicknesses to find the effects on the recovery rate. The highest rate of oil recovery was found in the case of a contact angle of $45^{\circ}$ and downward pickup. Furthermore, an optimal belt speed was found to reach the saturated recovery rate for a given oil thickness.

• International Journal of Contents
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• 제5권4호
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• pp.30-34
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• 2009

Many studies have been done on the integral imaging pickup whose objective is to get efficiently elemental images from a lens array with respect to three-dimensional (3D) objects. In the integral imaging pickup process, it is necessary to render an elemental image from each elemental lens in a lens array for 3D objects, and then to combine them into one total image. The multiple viewpoint rendering (MVR) is one of various methods for integral imaging pickup. This method, however, has the computing and rendering time problem for obtaining element images from a lot of elemental lens. In order to solve the problems, in this paper, we propose a parallel MVR (PMVR) method to generate elemental images in a parallel through distribution of elemental lenses into multiple threads simultaneously. As a result, the computation time of integral imaging using PMVR is reduced significantly rather than a sequential approach and then we showed that the PMVR is very useful.

• 한국소음진동공학회논문집
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• 제17권12호
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• pp.1246-1253
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• 2007

The recent issue of optical pickup actuators is to apply optical storage devices to mobile devices such as a cellular phone and PDA. It requires actuators to become smaller than conventional types. As the size becomes smaller, the magnetic force is reduced and the assembly of optical pickup actuators becomes more difficult. In addition, its dynamic characteristics are changed. In this paper, methods to improve magnetic forces and dynamic characteristics are suggested and the optimal result of the plate spring design is obtained. A diamond shape magnet and the fine pattern coil (FPC) are used to improve magnetic forces and damping elements are attached to decrease the peak magnitude of the mode instead of using structural damping, mostly for the purpose of improving the accuracy of the finite element simulation. To get more stable dynamic characteristics than conventional ones, a plate spring is applied to the optical pickup actuator and it is optimized with topology and parameter optimization to obtain the concept and the detail design, respectively.

• 정보저장시스템학회논문집
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• 제1권2호
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• pp.182-187
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• 2005

A large area micro mirror is an optical element that functions as changing an optical path by reflection in integrated optical system. We fabricated the large area silicon mirror by anisotropic etching using MEMS for implementation of integrated optical pickup. In this work, we report the optimum conditions to better fabricate and design, greatly improve mirror surface quality. To obtain mirror surface of $45^{\circ},\;9.74^{\circ}$ off-axis silicon wafer from (100) plane was used in etching condition of $80^{\circ}C$ with 40wt.% KOH solution. After wet etching, polishing process by MR fluid was applied to mirror surface for reduction of roughness. In the next step, after polymer coating on the polished Si wafer, the Si mirror was fabricated by UV curing using a trapezoid bar-type way structure. Finally, we obtained peak to valley roughness about 50 nm in large area of $mm^2$ and it is applicable to optical pickup using blu-ray wavelength as well as infrared wavelength.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.154-159
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• 2005

The next generation of optical storage systems requires higher numerical aperture (NA) objective lenses and shorter wavelength laser in order to improve the unit areal density. A blu-ray technology satisfies a miniaturization and a high capacity which are the requirements of the portable device. In this paper, we analyze the optical performance of hybrid micro lens and do active alignment. The hybrid micro lens is manufactured by using a wafer based fabrication technology. Optical components of hybrid micro lens are evaluated. The measurement of the optical power, the spot size and the wavefront error awe performed to evaluate the hybrid micro lens with NA 0.85. Using the measured data, we estimate if the performance of hybrid micro lens corresponds to the designed performance. After the performance of hybrid micro lens is evaluated, the integrated optical pickup and the hybrid micro lens are assembled by active alignment using UV curing and the optical performance of SFFOP is satisfied with BD specifications.

• 정보저장시스템학회논문집
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• 제2권1호
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• pp.79-84
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• 2006

The next generation of optical storage systems requires higher numerical aperture(NA) objective lenses and shorter wavelength laser in order to improve the unit areal density. A blu-ray technology satisfies a miniaturization and a high capacity which are the requirements of the portable device. In this paper, we analyze the optical performance of hybrid micro lens and do active alignment. The hybrid micro lens is manufactured by using a wafer based fabrication technology. Optical components of hybrid micro lens are evaluated. The measurement of the optical power, the spot size and the wavefront error are performed to evaluate the hybrid micro lens with NA 0.85. Using the measured data, we estimate if the performance of hybrid micro lens corresponds to the designed performance. After the performance of hybrid micro lens is evaluated. the integrated optical pickup and the hybrid micro lens are assembled by active alignment using UV curing and the optical performance of SFFOP is satisfied with BD specifications.

• 한국항해항만학회지
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• 제29권3호
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• pp.221-226
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• 2005

본 연구는 화물 운송 문제에 GIS 기법을 응용하여 화물의 수거 및 배송문제를 개선한 논문이다. 최근 국내 물류업체들은 인터넷을 기반으로 주문, 검색 및 화물의 추적 등을 온라인상에서 실행토록 하는 방법을 중시하게 되었다. 국내외 배송 관련 기업들은 빠른 서비스를 요 구하는 긴급주문의 비중이 커 가는 시장변환에 대처해서, 서비스 능력의 향상과 효율적인 차량관리를 위해서 GPS와 TRS 등의 정보통신기술을 이용하여, 기업의 배차업무를 개선하려고 노력하고 있다. 하지만 아직까지 배차 담당자의 의사결정을 지원할 수 있는 배차기법에 대한 연구는 거의 이루어지지 않고 있는 것이 현 실정이다, 본 연구에서는 GIS기반 하에서의 거리산정방법을 제안하고 이를 이용하여 차량운송 및 수거계획 알고리즘을 개발하였다. 또한 본 연구에서는 차량 및 화물정보를 GIS환경에서 실시간으로 조회해 볼 수 있도록 하였으며, 입출력자료와 차량 및 화물정보 조회결과를 GIS환경에서 구현하도록 하였다. 사용자들을 위하여 GUI-type 프로그램을 개발하고 실 예제를 통하여 Sample 출력을 보였다. 본 연구의 결과는 추후 약간의 수정 보완을 통하여 실제 물류센터에서의 운송계획 작성시 바로 적용할 수 있을 것이라고 판단된다.