• Korean Journal of Plant Resources
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• v.27 no.2
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• pp.174-182
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• 2014

This study was carried out to investigated the effects of soil type and light condition on seedling quality of rare and endemic plants Orostachys iwarenge and Orostachys iwarenge for. magnus. The best seedling quality of O. iwarenge and O. iwarenge for. magnus seedling were shown in Klasmann soil at non-shading or LED (Red+Blue) condition, 50% shading or LED (Red+Blue) condition, respectively. Survival of O. iwarenge seedling was not influenced by the period of experiment but survival of O. iwarenge for. magnus seedling in sandy soil conditions decreased significantly. Results of correlation analysis of seedling quality and survival rate, indicated that O. iwarenge showed a correlation of 0.8 or more at plant height, leaf length and fresh weight. O. iwarenge for. magnus showed a correlation of 0.8 or more at plant height, leaf width and leaf length. Especially, seedling survival of O. iwarenge and O. iwarenge for. magnus showed a correlation of 0.8 or more at first seedling survival and second seedling survival. It was important to manage the early seedling stages of O. iwarenge and O. iwarenge for. magnus. Therefore, seedlings with plant height (over 2.5~4 cm) and root length (over 3~5 cm) were grown vigorously at 35 days after the seedling was transplanted in mid-April in Klasmann soil of 72 plug cell tray at LED (Red+Blue) conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.7
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• pp.749-757
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• 1992

In this paper, as a more effective approach for maneuvering target tracking a realtime optical tracking system based of optical JTC(Joint Transform Correlator) which is capable of transforming the massive input target data into a few correlation peaks is implemented. And for real-time implementation the high resolution LCD(Liquid Crystal Display) spatialight modulator is used to construct the optical JTC system, and the mean binarization method is used to reduce the effects of background noises on correlation signal. From the good experimental results on maneuvering targets, the possibility of real-time moving target tarcking system based on optical JTC is a suggested.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.974-982
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• 2009

Photomixing techniques beating two optical signals with different wavelengths and strong correlations are also very useful techniques to make a continuous wave(CW) signals in the range of millimeter(mm) and terahertz(THz) frequencies. An optical double sideband-suppressed carrier(DSB-SC) technique is one of the popular techniques to generate two optical signals with different wavelengths and strong correlations. DSB-SC signals with strong correlations are generated by a CW modulation of an optical carrier with a local oscillator and an optical modulator. In the previous parers related the DSB-SC for producing the CW signals within the range of mm and THz frequencies, there have been no reports why the optical carrier should suppress. In order to clear that, we have analyzed and measured the characteristics of the mm-wave CW signals made by the DSB-SC photomixing in this paper. From our analysis and measurement results, compared with the case of the DSB with the maximized optical carrier, the power and phase noise have improved about 23.9 dB and 21 dBc/Hz(@ 1 MHz offset frequency) in the case of the DSB with the minimized optical carrier (that is to say, the DSB-SC). Consequently, it is evident reason that the optical carrier should sufficiently suppress to obtain the mm-wave CW signals with the high power and low noise. This paper has given very helpful data to make mm- and THz-wave CW signals using photomixing techniques with the DSB-SC because the reason why the optical carrier should be suppressed is reported in this paper based on the numerical and experimental results.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.293-296
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• 2007

본 논문에서는 UPS 기능을 갖는 단상 태양광 발전 시스템을 제안하였다. 제안하는 시스템은 태양광 어레이 (photovoltaic array)에서 최대전력을 얻기 위해 MPPT (maximum power point tracking)를 수행하는 컨버터, 계통전원 상태나 태양광 발전량에 상관없이 부하에 정현파 전압을 공급하는 인버터, 태양광 어레이에서 발전된 잉여전력을 계통으로 전달하거나 부하에 필요한 전력을 dc bus로 공급하는 인버터, 정전시 dc bus에 전력을 공급하는 양방향 컨버터 (bidirectional converter)로 구성된다. 제안하는 시스템은 발전된 전력을 계통으로 전달할 뿐만 아니라, UPS (uninterruptible power supply)기능도 수행하는 시스템으로 계통전압이 불안정하거나 정전시에도 부하에 안정적이고 깨끗한 전압을 항상 공급할 수 있다. 각각의 인버터, 컨버터, 및 양방향 컨버터는 dc bus를 공유하며, dc bus의 전압에 따라 동작상태가 결정이 된다. dc bus중심의 제어는 dc bus전압을 안정적으로 유지시키며, 부하에 걸리는 전압의 변동을 최소로 하고 시스템의 디자인 및 제어를 단순화한다. 모든 알고리즘과 제어기를 하나의 마이크로 컨트롤러로 구현하였고 제안된 시스템의 우수성을 실험을 통해 검증하였다.

• Proceedings of the KSRS Conference
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• 2008.03a
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• pp.219-223
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• 2008

초분광 영상은 기존의 다중분광 영상보다 많은 파장대의 영상을 취득하기 때문에 다양한 분야의 연구에 이용되고 있다. 하지만 밴드별로 취득하는 파장대가 짧고 밴드수가 많아, 밴드간의 높은 상관관계 및 노이즈 밴드가 존재한다. 이로 인해 기존에 알려진 분석기법의 적용결과가 제대로 도출되지 않는다. 따라서 초분광 영상을 이용할 경우, 노이즈가 많이 포함된 밴드를 제거한 후 영상분석을 하는 것이 보다 효율적이다. 본 연구에서는 초분광 영상(Hyperspectral Image)의 전처리 과정 중 노이즈 밴드 제거에 초점을 맞추었으며, 이를 위해 프랙탈 차원을 이용하였다. 프랙탈 차원 측정방법 중 삼각기둥 표면적 기법을 이용하였다. 프랙탈 차원을 측정하고, Continuum Removal 기법을 이용하여 경향을 살펴보았다. 경험적으로 구한 임계값을 통해 상대적으로 정보량이 적은 밴드를 노이즈 밴드로 판단하여 제거하였다. 실험 영상으로는 EO-1 위성에서 취득되는 Hyperion 초분광 영상을 사용하였다. 실험 결과 프랙탈 분석을 통해 Hyperion 초분광 영상의 노이즈 밴드를 자동으로 추출하여 제거할 수 있음을 확인하였다.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.4-6
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• 2020

태양광 모듈은 일사량과 온도에 의해 P-V 및 I-V의 특성이 변하여 최대 전력 점 추종 기업(MPPT, Maximum Power Point Tracking)이 필요하다. 기존의 기법들의 경우 모듈의 온도로 인해 개방전압이 변하거나 음영이 발생하면 태양광 모듈의 최대 전력 점을 추종하지 못한다. 본 논문에서는 태양광 패널에서의 P-V 및 I-V의 상관관계와 온도 변화에 대한 태양광 모듈의 최대 전력 점을 추종하는 기법을 제안한다. 본 논문에서 제안된 제어기법은 3kW 태양광 인버터 시스템을 구성하여 시뮬레이션을 통해 타당성을 검증하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.2
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• pp.37-44
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• 2004

In this paper, we performed the design and the development of the wide-band correlation board to be an important role in the autocorrelation spectrometer's building for the observation study of an extra-galaxy's spectral lines and the survey research of the special radio sources in field of the radio astronomy. In this research, the developed correlation board by using QUAINT correlator chip(made by NRAO) has maximum 100 MHz clock speed and operate at a intermediate frequency with 400 MHz bandwidth. For the Performance test we supply the 0.5 and 1.67 MHz rectangular wave, then we obtain the autocorrelation coefficients. The final results, which process by using FFT, get the almost same results compare with the theoretical correlation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.6
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• pp.400-407
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• 2003

In this paper an optical encryption system, which can decrypt the original image by using the autocorrelation terms of a JTC, is proposed. Unlike the classical JTC, the joint input plane of the proposed system is composed in a frequency domain not a spatial domain, thus it needs only one Fourier transformation. To use like this, the phase component appeared in the output plane of JTC should be considered. We presents the effect of phase and provides the solution. An original image is encrypted to a complex-valued random image. The original image is reconstructed using the autocorrelation terms which is the main drawback of JTC, therefore the proposed system is more suitable for JTC and real time processing. By computer simulation and optical experiment, the analysis for the phase effect and the performance of the proposed system are confirmed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7C
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• pp.712-722
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• 2002

We have investigated a novel optical decoder for a fiber-optic code division multiple access(CDMA) communication systems. The conventional optical encoder and decoder have the advantage of simple structure. However the number of users in the system is limited by the auto- and cross-correlation properties generated in decoding process. In previous studies, to improve the system performance, although they used an optical code that minimize the sidelobe and cross-correlation, could not yet find a novel methods for performance improvement in fiber-optic CDMA system. Thus, it is necessary to investigate the novel optical decode in order to improve the performance of system. In this paper, we schematize the AND gate logic element(AGLE) composed with 1$\times$2 or 1$\times$3 coupler and the optical thyristor and propose the novel optical decoder using K(weight) AGLE. The optical thyristor only passes the overlapped signal and clips other signals. Such a novel concept means that the optical thyristor can operate as a hard-limiter. We analyze the fiber-optic CDMA system using the novel optical decoder with simulation and is found that the novel optical decoder using the AGLE and optical thyristor excludes the sidelobe and cross-correlation intensity between any two sequences.

• The Bulletin of The Korean Astronomical Society
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• v.28 no.1
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• pp.75-75
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• 2003