• Title, Summary, Keyword: 프리즘 분석기

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Precise calibration of the angle of ncidence in spectroscopic ellipsometer (분광 타원해석기 입사각의 정밀 보정)

  • 김현종;김상열;이윤우;조현모;조용재;이인원
    • Korean Journal of Optics and Photonics
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    • v.10 no.3
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    • pp.208-213
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    • 1999
  • We proposed a new technique to precisely calibrate the angle of incidence in spectroscopic ellipsometer. The proposed technique can be useful to the thickness measurement of semiconductor thin films and optical thin films. The usefulness has been confirmed experimentally. We cut a block of optical glass into two pieces and made a prism as well as a slab using each piece. The apex angle and the angle of the minimum deviation of prism were measured. From these angles, the refractive index of glass material was calculated. From the analysis of the spectro-ellipsometric data collected near Brewster's angle, we could not only determine the error in the angle of incidence in the spectroscopic ellipsometer, but also calibrated the angle of incidence to the accuracy of 0.01 degree.

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Abstraction Method for Analysis of Mobility and Interaction in Process Algebra Using Behavioral Ontology (프로세스 대수에서 이동성과 상호작용을 분석하기 위한 행위 온톨로지를 이용한 추상화 방법)

  • Woo, Su-Jeong;On, Jin-Ho;Lee, Moon-Kun
    • The Journal of the Korea Contents Association
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    • v.11 no.9
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    • pp.63-75
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    • 2011
  • A number of process algebras have been proposed to develop distributed mobile real-time systems: pi-Calculus, Mobile Ambients Calculus, Bigraph, etc. However, as the systems get large and complex, the algebras become less suitable for understanding the interactions and mobility of the processes of the systems due to the size and complexity. Therefore it is necessary to handle the size and complexity for systematic understanding of the systems. This paper handles the size and complexity with a method of abstraction on sequences of interactions and movements of processes in the systems, which can be further organized in the form of hierarchically structured lattices, namely, Prism. The theoretical principle of the abstraction is based on a new concept of Behavior Ontology, which is extended from Active ontology. Prism allows the systems to be analyzed in the perspective of the lattices in Prism, which are characterized by the hierarchically organized behavioral properties of the developing systems, for systematic understanding the systems. In this way, the complexity of the interactions and the movements can be handled systematically in the semantically and hierarchically organized structure of the behavior.

Generation of Femtosecond Pulses in a Passively Mode-Locked 100 MHz Cr4+:YAG Laser (수동 모드 잠금된 100 MHz Cr4+:YAG 레이저에서의 펨토초 펄스 발생)

  • Cho, Won-Bae;Rotermund Fabian;Kim, Jong-Doo;Jeon, Min-Yong;Suh, Ho-Suhng
    • Korean Journal of Optics and Photonics
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    • v.16 no.6
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    • pp.535-541
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    • 2005
  • We report on the development of a passively mode-locked near-infrared femtosecond laser with Cr:YAG crystal that operates near room temperature. The laser wavelength could easily be tuned by using only the internal prism pair over 110 nm from 1400 nm to 1510 nm in cw and over about 30 nm in mode-locked operation, respectively Maximum cw output powers of 810 mW were obtained with $1.5 \%$ output coupler for absorbed pump powers of 7.6 W. For compensation of the internal group velocity dispersion, an IR graded prism pair was used. The Cr:YAG laser delivered nearly Fourier-transform limited pulses with a pulse duration as short as 64 fs at 100 MHz repetition rate. In the mode-locked regime, the laser was operating at 1510 nm with a spectral bandwidth of 44 nm. In order to avoid unstable mode-locking and power instabilities, self-built tubes were inserted into the beam path in the resonator and purged with N2 gas. Finally, output powers of the Cr:YAG laser were optimized to 250 mW fer long time stable mode-locked operation.

Characterization of refractive index profile in LiNbO3 waveguides fabricated by high temperature proton exchange method (고온 양자교환법으로 제작된 LiNbO3 도파로의 굴절률 분포)

  • Shin, Myung-Jin;Cho, Hyun-Ju;Lee, Jae-Cheul
    • Korean Journal of Optics and Photonics
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    • v.15 no.6
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    • pp.563-568
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    • 2004
  • The high temperature proton exchange (HTPE) method was used to fabricate optical waveguides based on LiNbO$_3$, which gives rise to low propagation loss and high polarization extinction ratio. To characterize the refractive index distribution of the fabricated waveguides, the guided modes of each waveguide were observed using the prism coupling method and then the refractive index profile was calculated by the inverse WKB method with the least square fitting. Finally, we showed how the HTPE parameters such as the temperature of PE, the concentration of lithium additive, and the time of PE effect the refractive index profile.

Relationship Between the Degree of Exophoria and Stereoacuity (외사위의 정도와 입체시의 관계)

  • Shin, Hoy-Sun;Lee, Sun-Haeng;Yun, Mi-Ok;Kim, Mi-Yeon;Bea, Hong-Sup;Park, Sang-Chul
    • Journal of Korean Ophthalmic Optics Society
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    • v.14 no.2
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    • pp.41-46
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    • 2009
  • Purpose: Stereopsis is one of primary characteristics for assessment of binocular function. The purpose of this study was to determine the possible relationship between the degree of exophoria and stereoacuity at near. Methods: 110 exophores (male n=71, female n=39, mean $age{\pm}SD=11.30{\pm}1.47$ years) without amblyopia, strabismus, and ocular and systemic pathology were studied. Subjects were also excluded if they had visual acuity poorer than 0.8 in either eye or vertical phoria greater than 1 prism diopter. Clinical tests were performed for near phorias by von Graefe technique using a Digital Refractor (CDR-3100, Huvitz, Korea) with chart (Predio CDC-4000, Huvitz, Korea), and for stereoacuity using the Titmus fly. Results: A one-way analysis of variance revealed that mean values of the stereoacuity classified according to the degrees of the exophoria were not significantly different (p>0.05). Conclusions: Based on the result of this study, it was found that there was no relationship between the degree of exophoria and stereoacuity.

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An Epidemiologic Survey of Strabismus and Nystagmus in South Korea: KNHANES V (인구역학적 요인에 따른 한국인의 사시 및 눈떨림 유병률 조사: 제5기 국민건강영양조사 자료)

  • Lee, Ji Eun;Kim, Chang Zoo;Nam, Ki Yup;Lee, Seung Uk;Lee, Sang Joon
    • Journal of The Korean Ophthalmological Society
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    • v.58 no.11
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    • pp.1260-1268
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    • 2017
  • Purpose: Strabismus affects any age and represents various functional or non-functional eye problems. This population-based study was conducted to determine the prevalence of strabismus and nystagmus in South Korea according to various sociodemographic factors. Methods: We acquired data from the Korea National Health and Nutrition Examination Survey, a nation-wide cross-sectional survey and examinations of the non-institutionalized civilian population in South Korea (n = 30,538), conducted from July 2008 to December 2011. The prevalence of strabismus and nystagmus were verified, and associated sociodemographic factors was evaluated. Results: The overall prevalence of strabismic disorder in participants over 3 years of age was $1.4{\pm}0.1%$ (95% confidence interval [CI] 1.3-1.6%; $1.5{\pm}0.1%$ in males, $1.3{\pm}0.1%$ in females). The prevalence of exodeviation (15 or more prism diopters), esodeviation (10 or more prism diopters), vertical deviation, and other complicated strabismus and nystagmus was 1.0%, 0.2%, 0.2%, 0.1% and 0.1% respectively. The prevalence was highest in the 6 to 15-year age group ($1.9{\pm}0.3%$), and lowest in the 40 to 49 years age group ($0.8{\pm}0.1%$) (p = 0.005). There were no statistically significant differences for gender, region, residential area, household income, educational level and occupation. Conclusions: This nation-wide epidemiologic study demonstrated that the prevalence of strabismus and nystagmus according to various sociodemographic factors in South Korea was not statistically significant except for age group. Further investigations are required based on more surveys to better recognize the etiologic or risk factors that may be related to strabismus and nystagmus.

A GIS-based Analysis of Spatial Patterns of Individual Accessibility: A Critical Examination of Spatial Accessibility Measures (GIS를 이용한 접근성의 공간적 패턴 분석: 공간적 접근성 측정방법에 대한 비판적 검토)

  • Kim Hyun-Mi
    • Journal of the Korean Geographical Society
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    • v.40 no.5
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    • pp.514-532
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    • 2005
  • The purpose of this study is to critically examine conventional spatial measures of individual accessibility, which are based on the notion of spatial proximity, the single reference location, and the unlinked travel model. Using space-time accessibility measures with the travel-activity diary data set of Portland Metro, US, three expectations from spatial measures on spatial patterns of individual accessibility were empirically examined: (1) does individual accessibility decrease with an increase of distance from the CBD?; (2) does the spatial pattern of accessibility resemble that of urban opportunity density pattern?; and (3) are spatial patterns of individual accessibility of different socio- demographic population groups basically similar as people in the same area share the same geographic characteristics regardless of gender, race, age, and so on? First of all, the results showed that spatial variations in individual accessibility were not directly determined by spatial proximity and opportunity density as suggested by previous accessibility measures. The spatial pattern of individual accessibility was dramatically different from that of urban opportunity density High peaks of accessibility level were found far away from the CBD and regional centers. This finding might be associated with the importance of multi-reference locations and linked travels in shaping accessibility in reality. Furthermore, this study found that spatial patterns of accessibility clearly differ between men and women. These findings suggest that access requires more than proximity, and that the interaction between person-specific space-time constraints and the consequential availability of urban opportunities in space-time renders different accessibility experiences to people even in the same region, which would be one of the key ingredients missing from conventional spatial measures of accessibility.