• 정보저장시스템학회논문집
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• 제2권4호
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• pp.214-218
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• 2006

The focus and tracking servo system has been designed and proposed for the holographic memory of one dimensional spatial light modulator(SLM). The general servo method of conventional ODD system was based and modified for new holographic memory. The pre-grooved disc pattern and special dichroic coating were also included for new design in this research and the final separated optics are expected to be applied to the future general holographic memory as well as the one dimensional SLM holographic memory.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.217-221
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• 2005

Nowadays, HD(High Definition) broadcasting is popular all over the world. Many people want to record the HD level contents. BD(Blu-ray Disc) is developed to satisfy the needs. BD player for home movie system was manufactured already. ODD maker will produce BD Drive for PC(Personal Computer) within few months. Backward Compatibility is very important point in BD Drive. Until now, two OL(Object Lens), two optical pickup and two deck system are proposed. We suggest Single OL system in this paper. Single OL is composed of two optical parts and it's weight is heavy. We introduce the magnetic circuit composed of two 3-Pole magnets. In Spite of heavy OL, We achieve the New Actuator which has high performance.

• 정보저장시스템학회논문집
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• 제3권1호
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• pp.17-22
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• 2007

[ $TiO_2$ ] nanoparticles are added into UV curable resin to increase the refractive index of the cover-layer which is laminated on the media for cover-layer incident NFR. High refractive index is required for the cover-layer operating for the solid immersion lens optics with high effective numerical aperture. The eyepattern could be achieved from the cover-layer coated 20 GB ROM disc in which the refractive index of the cover-layer was 1.75, but the gap servo was unstable due to the rough surface of the cover-layer. Even though the light loss due to the nanoparticles is not serious, the rough microstructure is developed by adding the nanoparticles in the organic binder material. To achieve smooth surface for the stable gap servo, some special techniques should be added, for example the solubility of the nanoparticles should be enhanced by the optimization of the surface of the nanoparticles.

• 디지털콘텐츠학회 논문지
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• 제14권1호
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• pp.15-23
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• 2013

저전력과 새로운 응용의 대용량 데이터 처리 요구에 따라 저장장치로 하드디스크 대신 빠른 입출력 성능을 가진 SSD(Solid State Disk/Drive)를 활용한 저장 시스템이 등장하고 있으며 다양한 처리 데이터단위와 out-place-update, 제한된 지우기 횟수 등의 SSD 고유의 문제점을 극복하는 방안에 대한 연구가 활발하다. 그러나 빈번한 임의 쓰기를 발생하는 소규모 특정 데이터를 하드디스크나 SSD에 저장하는 경우 성능 및 안정성 저하 문제는 아직 완전히 해결하지 못하고 있다. 본 논문에서는 NVRAM의 바이트 단위의 빠른 읽기/쓰기와 비휘발성 그리고 인덱스 페이지 내 실제 데이터 변경 크기가 블록 크기보다 작다는 특성을 활용하여 빈번한 임의 쓰기를 요구하는 인덱스를 바이트 접근이 가능한 NVRAM에 저장하는 시스템의 구조를 제안한다.

• 한국통신학회논문지
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• 제31권11C호
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• pp.1052-1057
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• 2006

본 논문에서는 고밀도 광기록 장치에서 발생하는 디스크 기울임 현상으로 인한 검출 성능 저하를 방지하기 위해서 디스크 기울임 분석기를 갖는 적응 등화 PRML 검출 방법을 VerilogHDL을 이용하여 구현하였다. 디스크 기울임의 분석을 위하여 고정된 패턴으로 일정한 간격마다 반복되는 동기 데이터를 이용하여 분석된 디스크의 기울임 정도를 측정하여 ROM에 저장된 등화기 계수값과 가지 메트릭의 기준값을 갱신한다. 이러한 방법은 지속적으로 계수값을 계산하여 갱신시켜줘야 하는 기존의 적응등화 방법에 비해 간단하게 각각의 계수값을 갱신시킬 수 있다. Hynix $0.35{\mu}m$ STD cell library로 회로를 합성한 결과 35K 정도의 게이트를 필요로 하고 최대동작속도 140MHz의 성능을 보였다.

• 정보저장시스템학회논문집
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• 제10권2호
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• pp.32-38
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• 2014

Heat emission from the laser diode used in the optical disc drive and the defects from the increased temperature at the system have attracted attentions from the field of the information storage device. Thermoelectric refrigerator is one of the fine solutions to solve these thermal problems. The refrigeration performance of thermoelectric device is dependent on the thermoelectric material's figure-of-merit. Meanwhile, high electrical contact resistivity between metal electrode and p- and n-type thermoelectric materials in the device would lead increased total electrical resistance resulting in the degeneracy in performance. This paper represents the manufacturing process of the PbTe-based material which has one of the highest figure-of-merit at medium-high-temperature, ~ 600K to 900 K, and the nickel contact layer for reduced electrical contact resistance at once, and the results showing the decent contact structure and figure-of-merit even after the long-term operation environment.

• 한국기계가공학회지
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• 제6권3호
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• pp.85-91
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• 2007

This study was carried out to minimize the lifting force of a two hinge type stand mechanism. This unit is designed for the display devices in order to enhance the ergonomics for effective height adjustment and maintenance at any preferred position. The unit will be very useful for the mechanism fabricated with a coil spring and disc springs as a torque generator. The maximum and the minimum torque value should be calculated initially for the smooth lift. And the reasonable torque distribution is necessary to prevent any auto lift and auto dropping at any position because the torque generated by coil spring is more sensitive than disc spring in tilting the position. Therefore, the analysis of the coil spring is requisite to issue the specific torque value depending on the distorted angle with securing reliability of a long time storage condition. After the theoretical torque value was calculated, the evaluation was carried out by making a proto-type sample, then distorted angle was updated by experiment. The result of this study can readily be applied to various units for the optimization of the smooth lift.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1454-1457
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• 2003

This study was carried out to minimize the lifting force of a two hinge type stand mechanism. This unit is designed for the display devices in order to enhance the ergonomics for effective height adjustment and maintenance at any preferred position. The unit will be very useful for the mechanism fabricated with a coil spring and disc springs as a torque generator. The maximum and the minimum torque value should be calculated initially for the smooth lift. And the reasonable torque distribution is necessary to prevent any AUTO LIFT and AUTO Drooping at any position because the torque generated by coil spring is more sensitive than disc spring in tilting the position. Therefore, the analysis of the coil spring is requisite to issue the specific torque value depending on the distorted angle with securing reliability of a long time storage condition. After the theoretical torque value was calculated, the evaluation was carried out by making a proto-type sample, then distorted angle was updated by experiment. The result of this study can readily be applied to various units for the optimization of the smooth lift.

• 한국유체기계학회 논문집
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• 제11권2호
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• pp.20-28
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• 2008

Recently, butterfly valves are used as control valves for industrial process. However, there are not so many reports on cryogenic butterfly valves in spite of broad application in LNG storage station and LNG carriers. Present study is focused on the investigation of the detailed hydrodynamic and aerodynamic characteristics of cryogenic butterfly valves to contribute to the operation during the handling on LNG transportation system, and to the practical utilization in design of butterfly valves and actuators. The results show that large recirculation vortices in the region downstream of the valve are founded and the cavitation flows are intensively generated on the surface of valve disc at the relatively small opening angle. The aerodynamic characteristics, lift, drag and torque, acting on the valve disc are calculated. The pressure distribution and the pressure loss coefficient of the cryogenic butterfly valve show almost similar pattern with those of the butterfly valve which is used on the normal temperature.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.26-30
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• 2005

Stamper surface temperature is very critical in replicating the high density optical disc substrates using injection molding as the pit or land/groove patterns on the optical disc substrate have decreased due to the rapid increase of areal density. During the filling stage, the polymer melt in the vicinity of the stamper surfaces rapidly solidifies and the solidified layer generated during polymer filling greatly deteriorates transcribability and fluidity of polymer melt. To improve transcribability and fluidity of polymer melt, stamper surface temperature should be controlled such that the growth of the solidified layer is delayed during the filling stage. In this study, the effect of heating on replication process was simulated numerically. Then, an injection mold equipped with instant active heating system was designed and constructed to raise the stamper surface temperature over the glass transition temperature during filling stage of the injection molding. Also, the closed loop controller using the Kalman filter and the linear quadratic Gaussian regulator was designed. As a result, the stamper surface temperature was controlled according to the desired reference stamper surface temperature.