• Current Optics and Photonics
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• 제2권1호
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• pp.34-38
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• 2018

An X-band microwave photonic (MWP) filter using switch-based fiber-optic delay lines has been proposed and experimentally demonstrated. It is composed of two electro-optic modulators (EOMs) and $2{\times}2$ optical MEMS-switch-based fiber-optic delay lines. By changing time-delay difference and coefficients of each wavelength signal by using fiber-optic delay lines and an electro-optic modulator, respectively, a bandpass filter or a notch filter can be implemented. For an X-band MWP filter with four channel elements, fiber-optic delay lines with the unit time-delay of 50 ps have been experimentally realized and the frequency responses corresponding to the time-delays has been measured. The measured frequency response error at center frequency and the time-delay difference error were 180 MHz at 10 GHz and 3.2 ps, respectively, when the fiber-optic delay line has the time-delay difference of 50 ps.

• 전자공학회논문지B
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• 제33B권7호
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• pp.147-153
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• 1996

For shape invariant recognitin of korean characters iwth noise, an optical wavelet SDF filter is proposed To preserve the features of a reference image and inimize effects of a random noise in the inpt image wavelet transformed images with different dialation parameters are used. And to adapt to divese variations in the combinatorial form, eCP-SDF filter synthesis algorithm is used. The proposed optical wavelet SDF filter is the type of the matched filter so that it can use the structure of 4f optical correlation system. The computer simulation results show that the proposed filter is useful in the noisy input.

• Current Optics and Photonics
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• 제3권2호
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• pp.111-118
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• 2019

The optical characteristics of a tunable flattened-pass-band fiber comb filter, based on the polarization-diversified loop configuration, are investigated using the $Poincar{\acute{e}}$-sphere representation. In the design process, the spectral flatness is checked quantitatively, and the tunability of the pass band is demonstrated experimentally. Theoretical calculations show that the filter also exhibits desirable dispersion and polarization properties. The orientation angles of rotatable wave plates for the wavelength tunability of the filter are obtained. Furthermore, we elaborate on the multiple angle loci produced by degeneracies through the combination of optical elements within the loop of the filter.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.268-269
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• 2000

We demonstrate a polarization insensitive waveguide filter using quantum well intermixing(QWI). The bandgap of epitaxial layer is modified from 1.55${\mu}{\textrm}{m}$ to 1.40${\mu}{\textrm}{m}$ using QWI and a Bragg grating filter is demonstrated using electron beam lithography technology. The fabricated waveguide filter has a 70% reflection efficiency and a 1.46nm filter bandwidth. Furthermore polarization insensitive transmission characteristics are observed. The device can be applied to photonic integrated circuits(PIC).

• 전자공학회논문지SC
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• 제47권5호
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• pp.24-32
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• 2010

본 연구에서는 Optical Flow Method의 추적 성능을 향상시키기 위한 전처리 알고리즘을 제안한다. 제안하는 알고리즘은 Median Filter, Binarization, Morphology, Canny Edge, Contour Detecting 및 Approximation Method를 기반으로 개발되었다. Optical Flow 추적 성능 향상 여부를 평가하기 위해 Lucas-Kanade Optical Flow 알고리즘에 개발된 전처리 알고리즘을 적용하고, 전처리 알고리즘이 적용되지 않은 Optical Flow 영상과 추적 결과를 비교 분석하였다. 또한, Median Filter와 Histogram Equalization으로 구성된 기존 전처리 알고리즘과의 결과 비교를 통해, 개발된 전처리 알고리즘의 추적 성능 향상여부를 평가하였다. 실험결과, 전처리 알고리즘을 적용하지 않은 영상과 기존 전처리 알고리즘을 적용한 영상은 특징영역의 분할이 이루어지지 않아, Optical Flow의 추적 정확도가 매우 낮게 나타났다. 반면, 개발된 전처리 알고리즘을 적용한 영상에서는 외곽선이 내외부로 세분화되고, 외곽선 트리가 구성됨에 따라 Optical Flow의 추적 성능이 매우 높게 나타났다.

• 한국광학회:학술대회논문집
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• 한국광학회 2004년도 제15회 정기총회 및 동계학술발표회
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• pp.298-299
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• 2004

We propose and theoretically analyze multi-functional integrated optical device based on figure-eight shaped birefringent Sagnac loops. Our analysis shows that the propose device exhibit many unique features which allows it to operate as a tunable high-Q comb filter with a good channel isolation, and the intensity transmission of the filter can be varied from zero to 100 percent.

• 한국광학회:학술대회논문집
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• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.76-80
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• 1989

Spatial filters were designed for 1 TW high power phosphate glass laser development. Laser beam should be expanded from 1 mm diameter to 200mm diameter. Pin hole size should be determined and most of incident energy should be transmitted through out to final spatial filter. Each pin hole size is determined by calculating encircled energy for Gaussian beam from the oscillator. The optical tube length of each spatial filter is corrected to have the best collimating quality by scew raytracing through the total system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.544-546
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• 2004

This paper designs and evaluates a complementary filter for fusion of inertial sensor signals. Specifically, the designed filter is applied to inverted pendulum control where the pendulum's angle information is obtained from low-cost tilt and gyroscope sensors instead of an optical encoder. The complementary filter under consideration is a conventional one which consists of low- and high-pass filters. However, to improve the performance of the filter on the gyroscope, we use an integrator in the filter's outer loop. Frequency responses are obtained with both tilt and gyroscope sensors. Based on the frequency response results, we determine appropriate parameter values for the filter. The performance of the designed complementary filter is evaluated by applying the filter to inverted pendulum control. Experiments show that the performance of the designed filter is comparable to that of an optical encoder and low-cost inertial sensors can be used for inverted pendulum control with the heir of sensor fusion.

• 한국광학회:학술대회논문집
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• 한국광학회 1991년도 제6회 파동 및 레이저 학술발표회 Prodeedings of 6th Conference on Waves and Lasers
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• pp.177-180
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• 1991

본 연구는 광 패턴 인식을 위한 사진 위상 필터(QPOG)를 분석하였다. 사진 위상 필터를 이용하여 광 패턴 인식을 한 경우 특정한 패턴에 대해서는 판별력이 뛰어나지만 한 패턴이 다른 패턴의 부분 패턴이 되면 판별력이 떨어짐을 알 수 있었다.

• ETRI Journal
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• 제31권2호
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• pp.231-233
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• 2009

We propose a nonreciprocal filter based on coarse wavelength division multiplexing (CWDM) that reduces the upstream channel insertion loss in a passive optical network (PON). We also propose a method to increase the number of channels/optical network units (ONUs) in PON systems using the proposed filter to reduce the service cost per subscriber. Experimental results show that the PON system with the proposed 4-channel filter can reduce the power budget of the upstream and increase the number of ONUs by 3 to 4 times that of a conventional time-division multiplexing PON.