• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.3
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• pp.539-546
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• 1997

In this paper, we proposed a new mehtod to analyze the performance degradation by timing jitters in the APD (avalanche photodiode) receivers of intensity modulation/direct detection digital optical communication systems where raised cosine pulse-shaping filters are used to reduce the effect of noise while minimizing intersymbol interferences. The proposed analytical method is an extension of an analytical method we have already developed for pin diode receivers, and incorporates the effects of APD's multiplication factor and resulting shot noise. Using the proposed analytical method, we derive an approximated power penalty due to timing jitters based on an assumption of Gaussian distribution for timing jitters, and compare with that of the conventional analytical method. The results obtained from the proposed analytical method show that conventional analytical methods underestimate the influence of timing jitters on the reciver performance. The results also show that APD's multiplication factor which optimizes receiver sensitivity is smaller than that obtained by the conventional analytical method.

• Journal of Korean Society of Forest Science
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• v.95 no.2
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• pp.155-159
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• 2006

An efficient method for in vitro propagation of the medicinal plant Hovenia duleis, was established. Plantlets for micropropagation of H. dulcis were obtained from in vitro germinated seeds. The effectiveness of various levels of cytokinins (BAP, Kinetin and TDZ) on multiple shoot formation from stem nodes was tested. BAP (1.0 mg/L) treatment induced highest number of multiple shoots. The growth pattern of plantlet on various culture media was undertaken. The shoot elongation was optimal on 2MS basal medium without growth regulators. The in vitro rooting ability of H. dulcis shoots was examined with two-auxins IAA and IBA. The IAA (1.0 mg/L) treatments induced earliest rooting with maximum number of roots and root growth. Rooted shoots were transferred directly to small pots with artificial soil and such established plant exhibited a normal growth pattern similar to wild plantlet.