• Proceedings of the Optical Society of Korea Conference
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• 2004.07a
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• pp.22-23
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• 2004

최근 광통신 기술은 크게 진보하였다. 광통신 기술의 발전은 다양한 광부품들의 성능 향상 및 가격 저렴화를 불러일으켰으며, 이러한 광부품들은 광통신 기술 이외의 다양한 분야에서도 폭넓은 으용가능 성을 보이고 있다. 예를 들어, Photonics 기술을 활용하여 고전적으로 전기적 소자만을 활용하여 구현에 왔던 microwave 기능을 구현할 수 있으며, 이러한 시도는 새로운 형태의 microwave 활용 시스템 구조를 가능케 한다. 본 노문에서는 연세대학교 Microwave Photonics 국가지정연구실에서 수행된 연구 결과를 바탕으로 photonics 기술을 활용한 microwave 기능 구현 방법을 소개하고자 한다.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.6-7
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• 2000

Microwave Photonics (MWP) 란 광신호와 GHz 이상의 고주파수 전기신호 간의 상호작용을 이해하고 이를 응용하는 연구 분야이다. 최근 무선통신과 광통신의 접속, antenna remoting, phased-array antenna 등의 응-용 분야에서 MWP 기술에 대한 관심이 날로 증가하고 있다. 본 논문에서는 MWP 기술을 4개의 세부분야로 분류하여 각 세부분야에 대한 간단한 소개를 하고자 한다. (중략)

• ETRI Journal
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• v.38 no.1
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• pp.70-80
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• 2016

This paper addresses the problem of robust waveform design for distributed multiple-radar systems (DMRSs) based on low probability of intercept (LPI), where signal-to-interference-plus-noise ratio (SINR) and mutual information (MI) are utilized as the metrics for target detection and information extraction, respectively. Recognizing that a precise characterization of a target spectrum is impossible to capture in practice, we consider that a target spectrum lies in an uncertainty class bounded by known upper and lower bounds. Based on this model, robust waveform design approaches for the DMRS are developed based on LPI-SINR and LPI-MI criteria, where the total transmitting energy is minimized for a given system performance. Numerical results show the effectiveness of the proposed approaches.

• 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.

• Laser Solutions
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• v.16 no.2
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• pp.16-18
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• 2013

In this paper, we fabricated breathable films on the use of microwave oven by using UV nanosecond laser micromachining, and the number of micro-grooves on the film is controlled for different oxygen transfer rate(OTR). As different number of micro-groove, the breath films of 100,000cc, 120,000cc, and 150,000cc can be fabricated. The breath film package of 120,000cc is used for the experiment of steaming a sweet potato. At the result, the sweet potato is well-cooked with enough moisture in the package not bursted.

• Optical Science and Technology
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• v.7 no.4
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• pp.53-62
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• 2003

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.01a
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• pp.137-140
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• 2018

In this paper, a new design method for the RF photonics system using the TRIZ proposes. A noble design scheme the RF photonics system configurations was obtained after application of the TRIZ contradiction analysis.

• Current Optics and Photonics
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• v.4 no.4
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• pp.361-367
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• 2020

An approach based on an integrated photonic Ti:LiNbO₃ Y branch has been proposed, designed, and analyzed for the microwave instantaneous frequency measurement (IFM). By designing the Y branch with length L = 6545 ㎛ and refractive index N_TE - N_TM = 0.0764, a complementary optical filter with free spectral range (FSR) of 600 GHz is constituted, which results in a maximum measureable frequency of 300 GHz being obtained. Theoretical analysis on the temperature stability of the Ti:LiNbO₃ Y branch shows that the FSR variation of the complementary filter is 0.3% for the temperature change of 100 K, which indicates that the IFM approach will have a better stability. All these results demonstrate that the proposed IFM approach has potential capability to be used for the increasingly higher microwave IFM with better stability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3559-3571
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• 2015

This paper addresses the problem of signal acquisition with a sparse representation in a given orthonormal basis using fewer noisy measurements. The authors formulate the problem statement for randomly measuring with strong signal noise. The impact of white Gaussian signals noise on the recovery performance is analyzed to provide a theoretical basis for the reasonable design of the measurement matrix. With the idea that the measurement matrix can be adapted for noise suppression in the adaptive CS system, an adapted selective compressive sensing (ASCS) scheme is proposed whose measurement matrix can be updated according to the noise information fed back by the processing center. In terms of objective recovery quality, failure rate and mean-square error (MSE), a comparison is made with some nonadaptive methods and existing CS measurement approaches. Extensive numerical experiments show that the proposed scheme has better noise suppression performance and improves the support recovery of sparse signal. The proposed scheme should have a great potential and bright prospect of broadband signals such as biological signal measurement and radar signal detection.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.855-870
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• 2019

In this paper, an adaptive iterative algorithm is proposed for motion deblurring by using the salient intensity prior. Based on the observation that the salient intensity of the clear image is sparse, and the salient intensity of the blurred image is less sparse during the image blurring process. The salient intensity prior is proposed to enforce the sparsity of the distribution of the saliency in the latent image, which guides the blind deblurring in various scenarios. Furthermore, an adaptive iteration strategy is proposed to adjust the number of iterations by evaluating the performance of the latent image and the similarity of the estimated blur kernel. The negative influence of overabundant iterations in each scale is effectively restrained in this way. Experiments on publicly available image deblurring datasets demonstrate that the proposed algorithm achieves state-of-the-art deblurring results with small computational costs.