• 한국진공학회지
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• 제16권1호
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• pp.40-45
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• 2007

본 연구에서는 광전자 소자에 폭넓게 사용되는 ZnCdSe 화합물 반도체의 end-point인 CdSe의 유전함수 spectrum을 Vacuum Ultra Violet spectroscopic ellipsometry(타원편광분석법) 측정하여 분석하였다. 측정 결과는 변수화 모델을 이용하여 분석하였으며 그 결과 6 eV 이상에 존재하는 전자전이점들을 확인할 수 있었고 CdSe의 Critical Point(CP) 구조를 수치화 함으로써 온도나 화합물 함량에 따른 광특성 의존성 연구 등에 활용될 수 있는 database를 확보하였다.

• 한국진공학회지
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• 제18권1호
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• pp.60-65
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• 2009

본 연구에서는 분광타원분석법을 이용하여 최근 주목 받고 있는 microwave dielectric materials 인 $BaSm_2Ti_4O_{12}$ 박막의 광 특성을 $0.92{\sim}8.6\;eV$ 에너지 영역에서 분석하였다. 광역 에너지영역에서 측정이 가능한 Vacuum Ultra Violet spectroscopic ellipsometer를 사용하여 시료의 광 스펙트럼을 측정 하였으며, 측정된 스펙트럼으로부터 $BaSm_2Ti_4O_{12}$ 박막의 광 특성을 얻기 위하여 Tauc-Lorentz 분산 함수를 이용하였고, 고 에너지 영역대의 새로운 피크구조 (structure) 를 최초로 발견하였다.

• Current Optics and Photonics
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• 제5권3호
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• pp.278-288
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• 2021

We propose a characterization method for the scattering property of microspheres using spectroscopic optical coherence tomography (OCT). To prove the effectiveness of the proposed method, we prepare solutions of different concentrations using microspheres ranging from 28 to 2300 nm in diameter. Time-frequency analysis is performed on the measured interference spectrum of each solution, and the resulting spectroscopic information is converted into histograms for centroid wavelengths. The histograms present a very sensitive response to changes in the concentration and size of microspheres. We classify them into three categories according to their characteristics. When the histogram of each category is replaced with the corresponding calculated value of the scattering coefficient, each category is mapped to a different scattering-coefficient region. It is expected that the proposed method could be used to investigate the optical characteristics of a biological sample from OCT images, which would be helpful for optical diagnostic and therapeutic applications.

• Journal of Korean Vacuum Science & Technology
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• 제5권2호
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• pp.52-55
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• 2001

We report best dielectric function of ZnS by spectroscopic ellipsometry in the 3.7 - 6.0 eV photon energy range at room temperature. Using proper wet chemical etching procedure, natural overlayer was removed to obtain the pure dielectric function of ZnS, which had a higher <$\xi$$_2$> value at the El band gap peak than that previously reported. We also determined the dielectric property of the natural overlayer on ZnS by following the evolution of <$\xi$$_2$> with chemical etching. We found that the optical property of the overlayer was well described by amorphous semiconductor model.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제18권2호
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• pp.77-105
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• 2014

Medical imaging techniques have evolved to expand our ability to visualize new contrast information of electrical, optical, and mechanical properties of tissues in the human body using noninvasive measurement methods. In particular, electrical tissue property imaging techniques have received considerable attention for the last few decades since electrical properties of biological tissues and organs change with their physiological functions and pathological states. We can express the electrical tissue properties as the frequency-dependent admittivity, which can be measured in a macroscopic scale by assessing the relation between the time-harmonic electric field and current density. The main issue is to reconstruct spectroscopic admittivity images from 10 Hz to 1 MHz, for example, with reasonably high spatial and temporal resolutions. It requires a solution of a nonlinear inverse problem involving Maxwell's equations. To solve the inverse problem with practical significance, we need deep knowledge on its mathematical formulation of underlying physical phenomena, implementation of image reconstruction algorithms, and practical limitations associated with the measurement sensitivity, specificity, noise, and data acquisition time. This paper discusses a number of issues in electrical tissue property imaging modalities and their future directions.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2012년도 춘계학술대회
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• pp.47-48
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• 2012

• Journal of the Optical Society of Korea
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• 제18권4호
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• pp.350-358
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• 2014

The collapse of Langmuir monolayers of arachidic acid (AA) on water at various rates of molecular area compression has been investigated in situ by imaging ellipsometry (IE). The thickness of the collapsed AA molecules, which are inherently inhomogeneous, was determined by IE with a spatial resolution of a few microns. For the analysis, we determined the dielectric function of AA monolayers from 380 to 1690 nm by conventional spectroscopic ellipsometry. Compression rates ranged from 0.23 to $0.94{\AA}^2/min$. A change of multilayer domains was observed in the in situ IE images. Lower compression rates resulted in more uniform collapsed films. Our experimental results correspond with previous theoretical simulations.

• 한국표면공학회지
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• 제29권6호
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• pp.666-672
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• 1996

The optical property of CdTe thin film is important for applications such as the compound semiconductor type solar cells. CdTe films are prepared by RF sputtering at various substrate temperature between $25^{\circ}C$ and $300^{\circ}C$, then, annealed in argon gas environment at $400^{\circ}C$. The annealing process of the thin film caused variation in the film structure and the composition of films. The deformation of CdTe thin film was observed by X-ray diffractometry. After annealing, the grain size increased and the portion of the non-crystalline CdTe reduced. Futhermore, the structure of sputtered CdTe film grown at the substrate temperature more than $250^{\circ}C$ was enhanced in the (111) direction of zincblend structure. There was a discrepancy, in the spectroscopic ellipsometer spectrum, between the single crystal CdTe and the sputtered CdTe thin films, especially in the region over 3.2eV. An oxidation layer was found on the CdTe thin film by spectroscopic ellipsometry analysis.

• 천문학회보
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• 제37권1호
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• pp.57.1-57.1
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• 2012

We present a spectroscopic study of the globular clusters (GCs) in the giant elliptical galaxy (gE) M86 in the Virgo galaxy cluster. Using the spectra obtained from the Multi-Object Spectroscopy (MOS) mode of Faint Object Camera and Spectrograph (FOCAS) on the Subaru Telescope, we measured the radial velocities of 25 GCs, the metallicities of 16 GCs, and the ages of 8 GCs in M86. The mean velocity and the vocity dispersion of the GCs are < ${\upsilon}_p$ > = -354 ${\pm}$ 80 km/s and ${\sigma}_p$ = 292 ${\pm}$ 32km/s, respectively. The M86 GC system shows some rotation with a large uncertainty and the velocity dispersion of the blue GC system is 60 km/s larger than that of the red GC system. The mean metallicity and age of M86 GCs are <[Fe/H]> = -1.13 ${\pm}$ 0.47 and = 9.7 ${\pm}$ 4.0 Gyr, respectively. We found one GC younger than 5 Gyr. We discuss the spectroscopic results of the M86 GC system in comparison with the GC systems in other gEs.

• 한국광학회지
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• 제14권3호
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• pp.272-278
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• 2003

분광타원법을 이용하여 PDP용 ITO박막의 광학상수 및 패턴을 분석하였다. ITO 박막의 광물성은 로렌쯔 진동자 모델을 사용하고 ITO의 패턴에 의한 효과는 전체빔이 ITO와 유리기층을 덮는 면적비 가중치를 가진 반사율 평균방법으로 반영시켰다. PDP 다층박막을 구성하고 있는 유리기층 위의 ITO박막 패턴이 타원데이터에 미치는 영향을 분석하여 ITO가 패턴에서 차지하는 면적비를 결정하였다. 측정된 분광타원데이터에 최적맞춤한 ITO의 상대면적값이 예측값과 보이는 차이를 검토함으로써 분광타원법을 사용한 ITO패턴분석의 한계와 이를 극복하는 방법을 제시하였다.