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RISS 인기검색어
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- 저자 : Dejun Feng (검색결과 6 건)
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Electronic voltage tuning of all-fiber Mach-Zehnder interferometer
Feng, Dejun,Choi, Dong Hoon,Choi,Suk-Ho 경희대학교 자연과학종합연구원 2002 자연과학논문집 Vol.8 No.-
The electric voltage tuning performance of an all-fiber Mach-Zehnder interferometer which has unequal arm-length is studied in this paper. This interferometer consists of two 3dB fiber directional couplers, with one arm is affixed to a Piezoelectric Translators (PZT). When the voltage applied on PZT changes, the output interferometric pattern will shift accordingly. The transmission period of the interferometer is 2.24nm. When the direct current electric voltage changes from 28.7volt to 28.7volt, the pattern will shift for nearly one of its own period. The tuning sensitivity is about 0.038nm/volt, and the linearity is 0.9991. Also, the relationship between the physical path length difference of the two arms and the interval of adjacent interferometric peaks is discussed. This component has potential important applications in electric sensing measurement and optical fiber communication field.
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Numerical study of Non-uniform Refrection Volume Holographic Grating
Feng, Dejun,Choi, Dong Hoon,Choi, Suk-Ho 경희대학교 자연과학종합연구원 2002 자연과학논문집 Vol.8 No.-
The properties of non-uniform reflection volume holographic grating are analyzed in detail using a matrix method in this paper. The diffraction spectra of non-uniform volume holographic are numerically simulated with computer. A kind of non-uniform refractive index distribution is used in simulation. Several factors that can influence the spectra of non-uniform volume holographic grating are amply analyzed. The simulation results are in accordance with the analyzing results by the method of solving nonlinear differential equations and our previous experimental results.
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Spatial Orientation of Indoor Fire Ignition Based on Monocular Vision and Virtual Scene
Yakun Xie,Jun Zhu,Yukun Guo,Dejun Feng,Dejun Feng 한국차세대컴퓨팅학회 2022 한국차세대컴퓨팅학회 학술대회 Vol.2022 No.10
The spatial orientation of fire ignition can support an automatic fire suppression system (AFSS). However, due to the ambiguity of 2D images, most of the existing methods tend to study fire detection and cannot carry out spatial orientation. To solve this problem, we propose a spatial orientation method of indoor fire ignition based on monocular vision and virtual scenes. First, a hierarchical virtual scene construction method is proposed to realize the rapid construction of indoor scenes. Second, the characteristics of the fire are analyzed to obtain fire ignition in a 2D image. Finally, the spatial orientation of indoor fire ignition is calculated by analyzing the characteristics of fire attachment and the principle of three-dimensional imaging. The experimental results show that the absolute error of the spatial orientation of our method is 10.27 cm, and the relative error is 4.08%, which can meet the needs of AFSS.
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Dejun Li,Zhihui Xia,Zhi Deng,Xianghong Liu,Fuying Feng 한국유전학회 2013 Genes & Genomics Vol.35 No.6
To construct a linkage map enriched with tapping panel dryness (TPD)-related markers, we firstly utilized rubber tree ESTs associated with TPD to develop intron length polymorphism (ILP) markers. In this study,52 new ILP markers were further developed. Together with the ILP markers previously reported, 102 ILP markers developed from TPD-related ESTs were analyzed within 39 Hevea germplasm in detail. The PCR success rate and polymorphism rate of ILP markers was 97.06 and 61.62 %,respectively. The results based on PCR amplification and sequence analyses provided the evidences on cross-species/genera transferability of rubber tree ILP markers. The average polymorphic information content (PIC) values of 39 Hevea germplasm were about 0.1719, indicating that the genetic base of Hevea germplasm selected in this study was very narrow. Among 39 Hevea germplasm, the PIC value of wild rubber tree accessions was the highest, followed by Hevea species and cultivated rubber tree clones. Based on the similarity coefficient of ILP markers, 39 Hevea germplasm were divided into three groups including cultivated clones, wild accessions and Hevea species, suggesting that the classification was generally related to the characterization of Hevea germplasm. The ILP markers developed in this study further enriches the number of molecular marker in rubber tree, and the ILP markers will have a wide application in DNA fingerprinting, genetic diversity, marker-assisted selection and genetic mapping, etc. Moreover,the ILP markers transferred cross-euphorbiaceae family might be utilized in cassava, castor bean and physic nut.
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Highly AC Voltage Fluctuation-Resistant LED Driver with Sinusoid-Like Reference
Ning Ning,Zhenxiao Tong,Dejun Yu,Shuangyi Wu,Wenbin Chen,Chunyi Feng 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.2
A novel converter-free AC LED driver that is highly resistant to the fluctuation of AC voltage is proposed in this study. By removing large passive components, such as the bulky capacitor and the large-value inductor, the integration of the driver circuit is enhanced while the driving current remains stable. The proposed circuit provides LED lamps with a driving current that can follow the sinusoid waveform to obtain a very high power factor (PF) and low total harmonic distortion (THD). The LED input current produced by this driving current is insensitive to fluctuations in the AC voltage. Users will thus not feel that LED lamps are flashing during the fluctuation. Experiment results indicate that the proposed system can obtain PF of 0.999 and THD as low as 3.3% for a five-string 6 W LED load under 220 V at 50 Hz.
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Cho, Min-Ju,Yoon, Hyuk,Feng, Dejun,Yoon, Han-na,Choi, Dong-Hoon The Korean Infomation Display Society 2006 Journal of information display Vol.7 No.2
New photopolymers were designed and prepared using the photosensitive polymer binders. Holographic gratings were successfully fabricated in these photopolymer samples by a conventional optical interference method. We also investigated the effect of photocrosslink in the polymer binder on the diffraction behavior of a new photopolymer. The dynamic behavior of the grating formation was monitored by changing exposure intensity in terms of the diffraction efficiency. Particularly, we focused our efforts in observing the variation of diffraction efficiency during a post UV curing process. The surface topographical change of photopolymer layer before and after Vis/UV light exposure was observed by atomic force microscope (AFM). We inscribed the gratings of the glass diffuser on the surface of the photopolymer and investigated their diffusing properties. The diffusers with photopolymer with the main chain polymer binder showed relatively good viewing angle of around ${\pm}30{\circ}$. Two kinds of photopolymer showed similar uniformity of around 47-54%.
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