• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.5
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• pp.543-552
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• 2003

The effects of a directionally emitting and reflecting dielectric surface on the wall heat flux and medium temperature distribution are studied. The system is an infinite square duct enclosing an absorbing and emitting medium. The emissivity and reflectivity of opaque and gray wall vary with direction. Combined effect of conductive and radiative heat transfer is analyzed using finite difference and the direct discrete-ordinates method. The parameters under study are conduction to radiation parameter, optical depth, refractive index ratio. The results with directional and diffuse properties deviate each other when the conduction to radiation parameter is less than around 0.01. The wall heat flux differs fur optical thickness less than around 0.1. However, the medium temperature profiles differ for optical thickness greater than around 1. Deviations from diffuse property calculations are larger for hot wall with directional property than cold wall with directional property. As n increases from 1.5, the trend changes are observed fur refractive index ratio about n=6.10

• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.458-462
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• 2007

Spectroscopic ellipsometry is an excellent technique for determining dielectric function. To obtain critical point energy, standard analytic critical point expression is used conventionally for second derivatives of dielectric function which might increase high frequency noise than signal. However, reciprocal-space analysis offers several advantages for determining critical point parameters in optical and other spectra, for example the separation of baseline, information, and high frequency noise in low-, medium-, high-index Fourier coefficient, respectively. We used reciprocal Fourier analysis for removing noise and determining critical point of ZnCdSe alloy.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.199-200
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• 2008

In this paper, we researched optical characteristics of a holographic optical security system using a reflection recording material and optical random phase mask. The system have the property of optical security key with the phase mask. Also, a reflection recording geometry can reduced a size of the reconstruction system because a input beam to reconstruct a holographic image and a diffraction beam are the same side on the material.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.173-173
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• 2010

$Bi_4Ti_3O_{12}$ ($B_4T_3$) is a unique ferroelectric material that has a relatively high dielectric constant, high Curie temperature, high breakdown strength, and large spontaneous polarization. As a result this material has been widely studied for many applications, including nonvolatile ferroelectric random memories, microelectronic mechanical systems, and nonlinear-optical devices. Several reports have appeared on the use of Mn dopants to improve the electrical properties of $B_4T_3$ thin films. Mn ions have frequently been used for this purpose in thin films and multilayer capacitors in situations where intrinsic oxygen vacancies are the major defects. However, no systematic study of the optical properties of $B_4T_3$ films has appeared to date. Here, we report optical data for these films, determined by spectroscopic ellipsometry (SE). We also report the effects of thermal annealing and Mn doping on the optical properties. The SE data were analyzed using a multilayer model that is consistent with the original sample structure, specifically surface roughness/$B_4T_3$ film/Pt/Ti/$SiO_2$/c-Si). The data are well described by the Tauc-Lorentz dispersion function, which can therefore be used to model the optical properties of these materials. Parameters for reconstructing the dielectric functions of these films are also reported. The SE data show that thermal annealing crystallizes $B_4T_3$ films, as confirmed by the appearance of $B_4T_3$ peaks in X-ray diffraction patterns. The bandgap of $B_4T_3$ red-shifts with increasing Mn concentration. We interpret this as evidence of the existence deep levels generated by the Mn transition-metal d states. These results will be useful in a number of contexts, including more detailed studies of the optical properties of these materials for engineering high-speed devices.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.577-578
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• 2012

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.108-111
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• 2000

We will illustrate the topographical structure and optical structure of the merocyanine dye LB films obtained by the scanning near-field optical/atomic force microscopy (SNOAM). SNOAM was recognized as a powerful tool to modify the surface as well as to characterize the topography of the surface at atomic resolution, especially for optical reaction materials. SNOAM images showed that the topographical and optical structures of these films were not only depended on the chemical property but also physical property. In the continuous measurement on these dyes, the appearance of near-field optical transmission images showed a certain dependence on the kinds of dyes and the mutual mixing ratios of dyes. These experimental results suggest that there is a certain kind of interaction between these two dyes.

• Journal of The Korean Astronomical Society
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• v.19 no.1
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• pp.11-14
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• 1986

It is shown in this paper that the astigmatic property of single gravitational lens in static bounded gravitational field can be retained, if n-gravitating body as a whole acts simultaneously as gravitational lens.

• Korean Journal of Optics and Photonics
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• v.4 no.1
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• pp.9-14
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• 1993

We chose Bessel beamu[$J_o(ar)}$)l in order to investigate image forming property of the optical system with combined filter of amplitude and phase(CFAP). This paper investigated numerically the influence of number of nodes of these beams on the PSF, encircled energy(E), transmission ratio(TR), gain((;) for an aberrated(1aberration-free) optical system. These results showed that the property of PSF differ considerably from the one of the existing amplitude filter and that Bessel beam has super compensating effect for an optical system with spherical aberration. Particularly, the Bessel beam has less the size of central spot than the radius of Airy disk, this result can therefore be applied to the fabrication of semiconductor device.

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.214-217
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• 2017

AlSb is a promising material for optical devices, particularly for high-frequency and nonlinear-optical applications. We report the effect of growth temperature on structural properties of AlSb grown on GaAs substrate. In particular we studied the surface of AlSb with the growth temperature by atomic force microscopy, and concluded that optimized growth temperature of AlSb is $530^{\circ}C$. We also show the result of real-time monitoring of AlSb growth by in situ ellipsometry. The results of the structural study are good agreement with the previous reported ellipsometric data.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2003.11a
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• pp.171-172
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• 2003

직물의 외관 품위는 직물의 촉각뿐만 아니라 시각적인 자극에 의해서 크게 결정된다. 견직물이나 양모직물의 광택 등 자연스러운 광학적 특성은 특히 구성 섬유의 특성이나 구성사의 구조, 직물 조직 등과 밀접한 관계가 있는데 그 중 섬유단면형태가 가장 중요한 인자라고 할 수 있다. 따라서 단면형상에 따른 직물의 외관 감성 특히 시각특성에 미치는 영향을 알아보기 위하여 직물의 광택도를 측정하였다. 그 결과 섬유 단면의 요철이 많으면 광택도가 감소하면 섬유단면이 매끈한 부분이 많은 섬유는 광택도가 증가하였다. 그러나 이섬도 혼섬단면사로 구성된 직물은 광택이 우수하면서 은은함을 부여해주었다.