• 제목/요약/키워드: field emission characteristics

검색결과 641건 처리시간 0.037초

챔버를 이용한 농작지로부터의 기체배출량의 측정과 배출특성연구: 일산화질소(NO)와 아질산가스($N_2O$)의 배출량산정 (Measurements of Gases Emissions form Agricultural Soils and Their Characteristics with Chamber Technique: Emissions of NO and $N_2O$)

  • 김득수
    • 한국대기환경학회지
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    • 제17권2호
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    • pp.203-212
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    • 2001
  • During the growing season from June to August, 2000, the soil NO and $N_2$O fluxes were measured to elucidate characteristics of soil nitrogen emissions from different types of intensively managed agricultural soils at outskirts of Kunsan City, located in the western inland of Korea, Flux measurements were made using a closed chamber technique at two different agricultural fields; one was made from upland field, and the other from rice paddy field. The flux data from upland field were collected for both the green onion and soybean field. Concentrations of NO and $N_2$O inside a flux chamber ar 15 minute sampling interval were measured to determine their soil emissions. Either polyethylene syringes of teflon air bags were used for gas samples of $N_2$O and NO. The analysis of NO and $N_2$O was made using a chemiluminesence NO analyzer and GC-ECD, respectively no later than few hours after sample collection at laboratory. The gas fluxes were varied more than one standard deviation around their means. Relatively high soil gas emissions occurred in the aftermoon for both NO and $N_2$O. A sub-peak for $N_2$O emission was observed in the morning period, but not in the case of NO. NO emissions from rice paddy field were much less than those from upland site. It seems that water layer over the rice paddy field prevents gases from escaping from the soil surface covered with were during the irrigation and acts as a sink of these gases. The NO fluxes resulted from these field experiments were compared to those from grass soil and they were found to be much higher. Diurnal and daily variations of NO and $N_2$O emission were discussed and correlated with the effects of nitrogen fertilizer application on the increase of the level of soil nitrogen availability.

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반도체-반도체 사이의 거리 변화에 따른 전압-전류 특성 연구 (A Study on V-I characteristics depend on a distance between semiconductor-semiconductor)

  • 김혜정;김정호;천민우;박용필
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2004년도 제6회 학술대회 논문집 일렉트렛트 및 응용기술연구회
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    • pp.52-56
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    • 2004
  • The movement of electron in the semiconductor-gap-semiconductor was observed by the variation of V-I characteristic as a distance two ZnO(1010) single crystals. When the resistance between two crystals was $10^2{\sim}10^4{\Omega}$, V-I characteristics had the pattern of the field emission or ohmic contact. On the other hand, when the resistance was larger than $10^7{\Omega}$ by increasing the distance between two crystals, the effect of surface barrier was prominent. This result leads to the conclusion that both the field emission (or ohmic contact) and the surface barrier effect including the tunneling have the influence on V-I characteristics of mechanically contacted crystals.

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Efficiency Analysis of Acoustic Emission Control and Diagnostic Products Engineering

  • Irmuhamedova, R.M.;Sagatovo, M.V.
    • Journal of Multimedia Information System
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    • 제2권4호
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    • pp.317-326
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    • 2015
  • The paper deals with the analysis of the effectiveness of acoustic emission monitoring and diagnostics of engineering products. We discuss the results of the processing results of the field experiment to study the acoustic emission in the alloy and its welded joints in the presence of technological defects. We study the characteristics of the output of acoustic emission signals at different stages of elastic-plastic deformation of alloys. Analyzed acoustic chart and the output waveform of the acoustic emission for the different types of welds. Studies have shown the effectiveness of the Acoustic emission techniques and help improve the accuracy of non-destructive testing systems in problems of automation and control.

Conducted Emission of Inverter Power Sources for Resistance Welding

  • Mecke, H.;Dobbelin, R.;Winkler, T.;Fischer, W.
    • Journal of Power Electronics
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    • 제2권2호
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    • pp.124-129
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    • 2002
  • Invertigation electromagnetic emissione of inverter power sources resistance welding existing special aspects of EMI measurements in the field of resistance welding machines resulting from the power rating and operation mode of these machines have to be taken into account. The characteristics of the internal switching processes determined by the behavior of the applied power semiconductors, sunbber circuits and constructional aspect exert a great influence on the conducted emission welding inverters.

스크린 프린팅법에 의한 탄소나노튜브 전계방출소자의 제조기술 (Fabrication Techniques for Carbon Nanotube Field Emitters by Screen Printing)

  • 이만;손지하;주학림;정효수;고남제;이동구
    • 한국재료학회지
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    • 제12권6호
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    • pp.499-507
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    • 2002
  • The carbon nanotube emitters for field emission displays were fabricated by using screen printing techniques. The pastes for screen printing are composed of organic binders, carbon nanotubes (multiwalled or singlewalled), and some additive materials. The pastes were printed on Cr-coated/Ag-printed soda-lime glass substrates. From the I-V characteristics, the turn-on field of SWNT was lower than that of MWNT. The decrease in the mesh size of screen masks (i.e. increase in the opening size of the screen mesh) resulted in decreasing the turn-on field and increasing the electron emission current. When the carbon nanotubes were mixed with silver pastes, silver powders appeared to contribute to the vertically aligning of carbon nanotubes on a glass.

Laser Ablation of a ZnO:P2O5 Target under the Presence of a Transverse Magnetic Field

  • Alauddin, Md.;Park, Jin-Jae;Gwak, Doc-Yong;Song, Jae-Kyu;Park, Seung-Min
    • Bulletin of the Korean Chemical Society
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    • 제31권4호
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    • pp.798-802
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    • 2010
  • From time-resolved optical emission spectra, we have investigated the effects of a transverse magnetic field on the expansion of a plasma plume produced by laser ablation of a ZnO:$P_2O_5$ ceramic target in oxygen active atmosphere. The emission spectra of $Zn^{+*}$, $P^{+*}$, and $Zn^*$ neutrals in the presence of magnetic field turn out to be considerably different from those without magnetic field. The characteristics of the deposited films grown on amorphous fused silica substrates by pulsed laser deposition (PLD) are examined by analyzing their photoluminescence (PL), X-ray diffraction (XRD), and UV-visible spectra.