• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.260-261
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• 2002

파장 다중화(WDM) 방식의 광통신시스템에서 그림 1(a),(b)에 나타낸 바와 같이 한 쌍의 입출력 포트의 신호 방향을 바꾸는 광 가감기(Optical Add Drop Multiplexer)용의 2$\times$2 광 스위치가 사용된다 특히 멤스형 광 스위치는 삽입손실, 누화, 편광 및 파장 의존 손실 등이 낮아 많은 연구가 이루어지고 있다.(1-3) 광 스위치의 삽입손실을 낮추기 위해, 렌즈나 굴절률 맞춤액을 사용하는데, 광섬유를 정렬, 혹은 패키징할 때 렌즈나 맞춤액의 취급이 어렵다는 문제점이 있다. (중략)

• Korean Journal of Optics and Photonics
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• v.2 no.2
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• pp.59-66
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• 1991

Resonance angle and optimum thinckness of various thin metal films for surface plasmon resonance were calculated using an admittance diagram and optical constants and thickness of thin Ag films and Al films were determined by fitting the measured reflectance of surface plasmon resonance. Two wavelengths of an Ar ion laser were employed to select the unique optical constants which have the same thickness at two wavelengths. Also, when these films were exposed to the air, the shift of surface plasmon resonance was measured and the optical constants of modified thin films were determined.

• Korean Journal of Optics and Photonics
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• v.3 no.1
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• pp.1-10
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• 1992

A simple formula of the envelope method, which uses two envelopes fitted to the transmittance at quarter- and half-wave optical thicknesses, is derived to determine the optical constants (refractive index and extinction coefficient) and the thickness of weakly absorbing thin films. We applied the envelope method to ZnS and SiOx films deposited in a vacuum chamber and determined the optical constants at different deposition conditions. For SiOx films, the decrease in refractive index is consistent with the increase in stoichiometry as the backfilled oxygen pressure increases.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.322-323
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• 2005

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.6
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• pp.597-602
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• 2004

In practical applications of guided wave techniques, it is very important but also difficult to identify the propagating modes, and it is preferred to generate and detect a single or less dispersive mode. Also the noncontact method is required in the automated field application. So this paper considers a non-contact guided wave technique with enhanced mode-selectivity, where a laser beam illuminated through arrayed line slits is used as the transmitter and the air-coupled transducer is used as the receiver. The line arrayed laser illumination is a wavelength matching technique that ran generate only a few modes. The air-coupled transducer detects the leaky wave of the propagated guided wave, and by tuning its detection angle we ran detect the selected single mode. Experimental results for a 1mm thick aluminum plate proved the usefulness of the proposed method, and especially it was shown that this method was powerful in the generation and detection of the $a_0$ mode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.426-426
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• 2008

ZnO 박막과 Al이 도핑된 ZnO 다결정질 박막을 rf magnetron sputtering 방법을 이용하여 Si(100) 기판과 코닝글라스 기판에 증착하여 박막의 광학적 특성을 Spectro-scopic Ellipsometry (SE, Woollam사)와 UV-VIR-NIR Sphectrophotometry (SP, Varian사)를 사용하여 분석하였다. SE 측정은 입사각도 55도에서 75도까지 5도 간격으로 파장범위 250 - 1700 nm 에서 3 nm 간격으로 측정하였으며, SP 측정은 수직입사로 250-3000 nm 파장범위에서 1 nm 간격으로 투과도와 반사도를 측정하였다. 측정된 데이터들은 Lorentz Oscillator 모델과 Drude free electron 모델이 결합된 분산관계식을 사용하여 전산 맞춤을 하여 분석하였다. ZnO 박막의 optical band gap energy 는 3.3 eV로 측정되었으며, Al 도핑에 따른 자유전하농도가 증가에 의하여 Burstein-Moss 효과에 따르는 optical band gap energy의 증가 거동을 보였다. 또한 자유전하농도 증가에 따라 band edge 부근에서 나타나는 excitonic transition 에 기인하는 유전함수 피크의 broadening이 관찰되었으며, high frequency dielectric constant는 자유 전하농도에 관계없이 3.689${\pm}$0.05 eV 의 값을 가졌다. Drude free electron 모델을 사용하여 plasma frequency를 구하고 이로부터 얻어진 optical mobility 와 Hall mobility를 비교하여 ZnO계 다결정질 박막에서의 결정립계가 이동도에 미치는 영향을 고찰하고자 한다.

• The Journal of the Korea Contents Association
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• v.21 no.2
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• pp.631-640
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• 2021

The purpose of this study focuses on and explain the policy-determining factors that emerged in the process of revising customized wages for the National Basic Livelihood Security Act on December 30, 2014. This is an analysis of the reasons why the rapid revision of the welfare system could have been made at a certain time in a situation that did not progress despite the specific demand for revision of the law surrounding the blind spot. To this end, using Kingdon's policy flow model, which emphasizes the contingency of policy decisions, the flow of problems, political flows, and policy alternatives were reviewed respectively. In the course of each of these flows, the suicide incident of mother and 2 daughters in Songpa served as a major medium that played a large role in the policy-making process and the window of policy could be opened. As a result, This incident triggered social and policy interest in the issue of the National Basic Livelihood Security Act. It was found that the law was revised quickly, causing a great wave of waves as a social issue.

• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.267-276
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• 1997

We set up a four-wave holographic interferometer using a symmetric dual-beam illumination which is to measure in-plane and out-of-plane displacement simultaneously. In order to acquire the displacement phase map we applied the phase-shifting method and removed the noise of the phase map with least-squares fitting. In this approach the access to information relative to both the difference and sum of phases existing in the two arms of four-wave holographic interferometer was allowed. As a result, in-plane and out-of-plane displacement was measured to the accuracy of λ/40 and λ/100, respectively at λ=632.8nm

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.3
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• pp.261-266
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• 2019

Flow cytometry is an electrical detection system that provides precise and diverse optical properties to cells and micro particles. Flow cytometry, which provides multidimensional information including cell size and granularity through light scattering and fluorescence emission generated by the induction of light of a specific wavelength to the fluorescently treated cells or micro particles, plays an important role in biomedical and biophysical fields. However, it has some drawbacks such as high cost, size of the instrument and limitation in selecting fluorescent dyes. Therefore, in this paper, a low cost compact fluorescent detection system is developed using light-emitting diode and microcontroller. The proposed fluorescence detection system has a replaceable the light source/fluorescence filter/photodetector and constructed by 3D printer, so that the user can design a customized system according to the selected fluorescent dyes. The fluorescence intensity was measured by varying the number of fluorescently labeled cells, and the measured intensities showed a high linearity within the tested concentration ranges.

• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.54-59
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• 2008

We report on the measurements of absorption spectra from acetylene ($^{12}C_2H_2$) and hydrogen cyanide ($H^{13}C^{14}N$) for wavelength reference in the C-band (conventional band) region using a supercontinuum optical source generated from a mode-locked $Cr^{4+}$:YAG laser. The center wavelength of the mode-locked $Cr^{4+}$:YAG laser was 1510 nm and the pulse duration was 75 fs at 100 MHz repetition rate. The supercontinuum source achieved a flatness of ${\pm}5dB$ over a wavelength range of more than 400 nm, using a 20 m long photonic crystal fiber. The measured absorption spectra from acetylene ($^{12}C_2H_2$) and hydrogen cyanide ($H^{13}C^{14}N$) had more than 50 lines and were analyzed for wavelength standardization.