• 한국정밀공학회지
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• 제22권5호
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• pp.80-86
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• 2005

Optical performance evaluation results and an interference fringe pattern analysis of alignment errors for an optical head of a near-field receding (NFR) system are presented. The focusing unit is an optical head of a NFR system and is composed of a solid immersion lens (SIL) and an objective lens (OL). Generally, the size of the focusing unit is smaller than that of the conventional optical recording head. Hence there are difficulties to assemble the small focusing unit precisely. We composed an evaluation system with an interferometer and evaluated some focusing unit samples aligned and assembled by manual and present the obtained results. Using the conventional optical tool, Code V, a tolerance analysis of the alignment error between the SIL and the objective lens and an interference pattern analysis for the assembly error are executed. Then, through an analysis of the simulation results, the conceptual auto-alignment methodology using a neural network approach is considered.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.175-180
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• 2002

Loading/Unloading(L/UL) mechanism has been considered to be an alternative to contact start-stop(CSS) mechanism which eliminates stiction and wear associated with frequent start and stop process. It has other advantages including increased areal density due to lower flying height, reduced power consumption, and improved shock resistance. In order for L/UL to be Implemented in Near-field recording system properly, dynamics of optical flying head must be understood and optimized. In this paper the dynamic characteristics during loading process is analyzed numerically to investigate the effect of design parameters such as loading speed. slider shape, and initia conditions on the dynamic reponses of flying head..

• 한국통신학회논문지
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• 제30권4C호
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• pp.247-252
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• 2005

현재 DVD 시스템의 채널에서 디코더는 16비트 입력을 받아 8비트 데이터 심볼을 복원한다. 이러한 DVD용 변조 코드는 주 테이블(main table)과 부 테이블(sub table)로 이루어진 EFMplus 코드를 사용한다. 본 논문에서는 디코더 구현시 필요한 코드 테이블의 크기를 줄이기 위해 EFMplus 코드를 3개의 그룹으로 나눈 후 각 코드의 가지 수를 줄이는 방법을 제안하고 이 코드 테이블을 이용하여 디코더를 구현하였다. 이 방식은 기존의 테이블을 이용하여 디코딩할 때 필요한 코드 수 1376개를 750개로 약 $46\%$정도 감소시켜 EFMplus 코드를 구현할 때 필요한 ROM의 크기를 약 2배 정도 줄였다.