• 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).

• Design & Manufacturing
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• 제14권3호
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• pp.44-49
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• 2020

One of display trends today is development of high pixel density. To get high PPI, a small size of pixel must be developed. RGB pixel is arranged by evaporation process which determines pixel size. Normally, a fine metal mask (FMM; Invar alloy) has been used for evaporation process and it has advantages such as good strength, and low thermal expansion coefficient at low temperature. A FMM has been manufactured by chemical etching which has limitation to controlling the pattern shape and size. One of alternative method for patterning FMM is laser micromachining. Femtosecond laser is normally considered to improve those disadvantages for laser micromachining process due to such short pulse duration. In this paper, a femtosecond laser drilling for thickness of 16 ㎛ FMM is examined. Additionally, we introduce experimental results for controlling taper angle of hole by vibration module adapted in laser system. We used Ti:Sapphire based femtosecond laser with attenuating optics, co-axial illumination, vision system, 3-axis linear stage and vibration module. By controlling vibration amplitude, entrance and exit diameters are controllable. Using vibrating objective lens, we can control taper angle when femtosecond laser hole drilling by moving focusing point. The larger amplitude of vibration we control, the smaller taper angle will be carried out.

• 전자공학회논문지SC
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• 제48권1호
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• pp.24-30
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• 2011

본 연구에서는 안구 영상을 위한 OCT용 손잡이 형 프로브를 개발하였다. 프로브는 휴대하기 간편한 손잡이 형태로 구현하였으며, 어댑터의 대물렌즈를 교체함으로써 각막(cornea)과 망막(retina) 모두 영상화 할 수 있도록 설계 하였다. 시스템의 성능검증을 위해 in vivo로 실험용 쥐의 눈 영상을 2D로 획득하였으며, 획득한 영상을 3D 영상으로 재구성하였다. 3D 영상은 쥐의 미세한 부분의 구조를 잘 나타내었으며, 움직임에 의한 흔들림 현상(Motion artifact)이 나타나지 않았으므로 개발된 OCT시스템의 이미지 디스플레이 속도는 생체 내 실험 (in vivo)에 적합함을 알 수 있었다.

• 전자공학회논문지SC
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• 제44권4호통권316호
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• pp.67-73
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• 2007

광디스크 드라이브에서 일반적으로 광 픽업은 포커싱과 트래킹 서보 시스템의 결합된 동력한 시스템을 갖는다. 이 결합된 동력학 시스템은 서로의 구동간섭에 의하여 광디스크 드라이브의 성능을 저하시킨다. 특히 디스크의 표면에 결함이 존재할 경우에는 포커싱과 트래킹 서보 시스템의 구동간섭으로 인해 시스템이 안정화하는데 많은 시간이 소요되고 결함구간이 길어질 경우 광학 렌즈가 추종하던 트랙을 이탈할 수 있다. 본 논문에서는 이 문제점을 극복하기 위하여, 트래킹 에러와 포커싱 에러의 관측을 기반으로 광디스크 드라이브의 새로운 제어 방법을 제안한다. 결함이 존재할 경우 결합된 동력학 시스템에 대한 보상을 통하여 시스템의 안정화 시간을 감소시킨다. 동일한 표면 결함에 대하여 제안된 제어 방법의 개선된 성능은 실험을 통하여 검증하였다.

• 한국초등과학교육학회지:초등과학교육
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• 제22권1호
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• pp.121-129
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• 2003

The enhancement of inquiry skills has been emphasized as a important objective of science education for a long time. Of these, the observation is not only a simple and basic skill, but also a very important skill, in aspect of gathering informations about the nature of all things around us, through interaction between the sense organs of body and objectives. The purpose of this study is to investigate the results of observations about the grasshopper(Oxya chinesis), made by the elementary student from the 3rd to the 6th grade, and to make use of them as the basic materials for the observative teaming and the evaluation of the observation ability. Through this study, the collected items of observation are as follows For grasshopper, a total of observation items is 95, 70 using the sight sense, 13 using the tactile sense,7 using the olfactory sense. 3 using the palate sense and 2 using the auditory sense. In this study, the findings of elementary student's observation are as follows. 1. On the whole, most of students have observed mainly by the sight and the tactile sense, when observing the grasshopper. 2. It is showed a tendency that the observation ability of student is increased with the higher grade in elementary school. 3. As the grade ascends. the observations with operating are increased, also the quantitative expression and interpretation about them are increased. 4. In the case of same grade, there is no significant difference between students' gender, though girls' ability of the observation showed somewhat higher than boys' 5. Occasionally, the interpretations on the observative facts made by student, are inaccurate. Basis on the above results, we suggested some directions for the improvement of the observative learning program in science classroom of elementary school. First, the teacher have to serve as a guide and encouragement in the observative learning class, to be accomplished the various observation, which all the sensory organ can be used by student than the sight sense. Second, to get elevated the ability of observation, it is necessary that some experimental tools(magnifying lens, stereoscope, auxiliary implements etc.) are utilized. Third, the teacher have to make often endeavors showing an example of operation, to be activated the atmosphere of operative observation.

• 한국정보통신학회논문지
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• 제13권12호
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• pp.2693-2700
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• 2009

본 논문에서는 렌즈 배열에 의한 대용량의 3차원 집적 영상을 활용하기 위한 효율적인 압축 방법을 제안한다. 기존의 정지영상 압축 기법은 각 요소 영상간의 상관도를 적절하게 제거하지 못하여 압축 효율 및 화질 측면에서 낮은 성능을 보인다. 또한, 각 요소 영상을 1차원 스캔방법에 의해 분리하여 동영상 압축기법을 이용할 경우 요소 영상간 상관도를 효과적으로 제거하는 데 한계가 있다. 제안하는 방식에서는 2차원 참조기법에 의해 각 요소 영상을 분리하고, 이를 H.264/AVC의 다중 프레임 참조 기법을 이용하여 효과적으로 압축한다. 제안하는 2차원 참조 기법은 요소 영상의 수직, 수평 및 대각 방향의 상관도에 따라 최적의 참조 영상을 선택할 수 있어 가장 좋은 압축성능을 나타낸다. 실험 결과는 정지 영상 압축 방법에 비해 요소 영상을 분리하는 방법이 압축 성능을 향상시킴을 보이고, 제안하는 2차원 참조 기법이 1차원 스캔 방식에 비해 주관적 화질 및 객관적 성능에 있어 뛰어남을 보인다.

• Journal of the Optical Society of Korea
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• 제15권1호
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• pp.61-67
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• 2011

The confocal laser scanning microscopy and two-photon microscopy was implemented based on a single laser source and an objective lens. We imaged and compared the morphology of identical sites of ex vivo human skin using both microscopes. The back-scattering emission from the sample provided the contrast for the confocal microscopy. The intrinsic autofluorescence and the second harmonic generation were used as the luminescence source for the two-photon microscopy. The wavelength of the Ti:Sapphire laser was tuned at 710 nm, which corresponds to the excitation peak of NADH and FAD in skin tissue. The various cell layers in the epidermis and the papillary dermis were clearly distinguished by both imaging modalities. The two-photon microscopy more clearly visualized the intercellular region and the nucleus of the cell compared to the confocal microscopy. The fibrous structures in the dermis were more clearly resolved by the confocal microscopy. Numerous cells in papillary dermal layer, as deep as $100\;{\mu}m$, were observed in both CLSM and two-photon microscopy. While most previous studies focused on fibrous structure imaging (collagen and elastin fiber) in the dermis, we demonstrated that the combined imaging with the CLSM and two-photon microscopy can be applied for the non-invasive study of the population, distribution and metabolism of papillary dermal cells in skin.

• Journal of Chest Surgery
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• 제55권2호
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• pp.101-107
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• 2022

Background: Spread through air spaces (STAS) has recently emerged as a prognostic factor in lung adenocarcinoma, but little is known about the association of STAS and its grade with recurrence in neuroendocrine tumors (NETs). This study investigated the prognostic effect of STAS grade in NETs after curative resection. Methods: Seventy-seven patients were retrospectively reviewed, including 9 with typical carcinoid (TC), 6 with atypical carcinoid (AC), 26 with large cell neuroendocrine carcinoma (LCNEC), and 36 with small cell carcinoma (SCC). STAS was defined as the presence of floating tumor cells within air spaces in the lung parenchyma beyond the edge of the main tumor. STAS was classified as grade 1 or 2 depending on whether it was found within or beyond one ×10 objective lens field away from the main tumor margin, respectively. Results: Fifty-four patients (70%) had STAS, including 22% with TC, 50% with AC, 69% with LCNEC, and 86% with SCC. Patients with STAS had more nodal metastasis, lymphatic and vascular invasion, tumor necrosis, and tumor subtypes other than TC. Among STAS cases, grade 2 STAS was present in 33% of AC, 78% of LCNEC, and 87% of SCC. The 5-year recurrence-free survival (RFS) rate was 81%, 63%, and 35% in patients with no STAS, grade 1, and grade 2 STAS, respectively. Multivariate analysis found that grade 2 STAS was an independent negative prognostic factor for RFS. Conclusion: Although STAS itself was not associated with a poor prognosis, grade 2 STAS was an independent negative prognostic factor for RFS.

• 수완나부미
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• 제10권1호
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• pp.63-91
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• 2018

One of the goals of this article is to continue the momentum begun by emerging scholarship on theory and practice of writing about visual culture of and in Southeast Asia. I hope to offer culturally sensitive and embodied ways of looking at images and objects as sites/sights of cultural knowledge as further theoretical intervention. The argument put forward in my essay is three-fold: first, I critique the prevailing logocentric approach in the field of Southeast Asian Studies and I argue that in a postcolonial, global, and transnational period, it is important to be inclusive of other objects as sites/sights of social, political and cultural analysis beyond written and oral texts. Second, I argue that although it has its own political and theoretical problems, the evolving field of Visual Studies as it is practiced in the United States is one of many ways to decolonize the prevailing logocentric approach to Southeast Asian Studies. Third, I argue that if one reads these Euro-American derived theories of vision and visuality through the lens of what Walter Mignolo calls "colonial difference(s)," then Visual Studies as an evolving field has the potential to offer more nuanced local ways of looking at and understanding objects, vision, and visuality. Last, I point out that unlike in the West where there is an understanding of pure, objective and empirical vision, local Southeast Asian perspectives on objects and visions are more embodied and multi-sensorial. I argue that if one is ethically mindful of the local cultural ways of seeing and knowing objects, then the evolving field of Visual Studies offers a much-needed intervention to the privileged, lingering logocentric approach to Southeast Asian Studies. Moreover, these alternative methods might help to decolonize method and theory in academic disciplines that were invented during the colonial period.

• 한국광학회지
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• 제33권6호
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• pp.295-302
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• 2022

FHD급 고해상도 연성 내시경을 설계하기 위한 wedge prism 적용 방법을 연구하였다. 기존의 연성 내시경 광학계의 경우, 넓은 피사계 심도 범위에서 동일한 결상 성능을 얻기 위해 F 넘버를 크게 가져가거나 액체 렌즈를 적용하였다. 하지만 이는 추가적인 light guide와 기구물을 필요로 하여 광학계의 직경이 커진다는 문제점이 있다. 이를 해결하기 위해, 연성 내시경 광학계에 2매의 wedge prism을 적용하여 각 물체거리별로 상거리를 조절하였다. 먼저 설계한 내시경 광학계에 2매의 wedge prism을 대칭으로 배치하고, 각 물체거리별로 목표 결상 성능을 만족하는 상거리 값을 도출하였다. 그 다음, 상거리를 조절하기 위한 wedge prism 디센터 값을 도출하였다. 이 두 가지 데이터를 조합하여, 각 물체거리에서 목표 결상 성능을 만족하는 wedge prism 디센터 값을 다중구성으로 적용하였다. Wedge prism을 적용한 최적 설계 결과, 100 mm-7 mm의 전체 피사계 심도 범위에서, 분해능 178 cycles/mm에 대한 변조전달함수 20% 이상의 목표 결상 성능을 만족하였다.