• 제목/요약/키워드: Telecommunication

검색결과 6,363건 처리시간 0.041초

전력 유도 장애 시 통신 선로 케이블의 접지체와 유도원간의 이격거리에 의한 유도 잡음 영향 분석 (Analysis on the Effects of the Induced Noise with Change of the Separation Distance between Grounding Equipment at End of Telecommunication Line and the Inducting Facilities in Power Inducting Situation)

  • 최문환;이상무;조평동
    • 한국정보통신설비학회:학술대회논문집
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    • 한국정보통신설비학회 2007년도 학술대회
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    • pp.215-218
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    • 2007

  • In this paper, we have analyzed the effects from the change of separation distance between grounding equipment at end of telecommunication line and the inducting facilities in power inducting situation. In the result of measurement, we can see that as the separation distance between grounding equipment ant end of telecommunication line and the inducting facility become longer, the induced noise level and PIF level is decreased. From the another experiment results about the effect of changing the impedance size in both ends of telecommunication line, however, we already knew that as the ground impedance at either end of the telecommunication line become grower, the noise level is increased, and as the ground impedance at either end of the telecommunication line become smaller, the noise level is decreased. Hence we can not define the relationship exactly between separation distance from inducting facility to inducted facility and the induced noise level because when the grounding equipment is moved, its impedance size is changed too. In conclusion, changing the separation distance between grounding equipment at end of telecommunication line and the inducting facilities have not influence on the induced noise level.

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Low molecular amorphous spirobifluorene derivatives for blue electroluminescence

  • Lee, Hyo-Young;Oh, Ji-Young;Chu, Hye-Yong;Lee, Jeong-Ik;Kim, Seong-Hyun;Yang, Yong-Suk;Do, Lee-Mi;Zyung, Tae-Hyoung
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2001년도 International Meeting on Information Display
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    • pp.209-212
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    • 2001

  • We report the synthesis and characterization of new alkoxy substituted spirobifluorene derivatives. The spiro compounds having alkoxy hydrocarbon chains were readily soluble in common organic solvents, having improved film-forming properties and had a significantly reduced tendency to crystallize, resulting in increasing their service lifetime. The results of DSC showed that it was amorphous. The optical and electroluminescent spectra were characterized. Electroluminescence (EL) properties of three-layer light emitting diodes (LED) of $ITO/TPD/spirobifluorene/Alq_3/LiF/Al$ as the active layer were characterized. Blue emission peaking of the EL spectrum of the three-layer device at 402 nm and a luminance of 3,125 $cd/m^2$ were achieved at a drive voltage 12.8 V. The luminous efficiency was obtained to be 1.7 lm/W. The color coordinate in CIE chromaticity is (0.16, 0.09), which is in a pure blue region. The external quantum efficiency was obtained to be 2.0%. The results indicate that the spirobifluorene compounds having alkoxy hydrocarbon chains are strongly potential blue emitters for LED applications.

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Analysis and Countermeasures on the International Competitiveness of Telecommunication Service Trade between China, Japan, and South Korea

  • Gong Jing
    • Journal of Korea Trade
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    • 제26권7호
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    • pp.43-58
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    • 2022

  • Purpose - Based on the telecommunication service trade data of China, Japan, and South Korea from 2009 to 2019, this paper compares and analyzes the international competitiveness of the three countries' telecommunication service trade, and finds the existing problems in China through the comparison, so as to make reasonable planning and industrial development strategy, and find away to catch up. Design/methodology - The comparative analysis method was used to compare and analyze the international competitiveness of telecommunication service trade among China, Japan, and South Korea from the three aspects of market share, trade surplus, and export proportion represented by MS, TC, G-L, RCA, and CA. Findings - The international competitiveness of telecommunication service trade among China, Japan, and South Korea does not have competitive advantages. China is larger than Japan and South Korea, but only close to average globally, and its share of trade in telecommunications services is lower than Japan and South Korea's. Originality/value - This paper tries to explore international competitiveness in the field of telecommunication service trade, and through the comparison of five indicators to find problems in China, so as to put forward countermeasures to improve the international competitiveness of China's telecommunication service trade, and lay a foundation for subsequent research on the source factors of international competitiveness.

  • https://doi.org/10.35611/jkt.2022.26.7.43 인용 PDF