• Title/Summary/Keyword: X/E ratio

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Effect of $TiO_2$ Addition on the Secondary Electron Emission and Discharge Properties of MgO Protective Layer (산화마그네슘 보호막의 이차전자방출과 방전특성에 미치는 산화티타늄첨가의 효과)

  • Kim, Young-Hyun;Kim, Rak-Hwan;Kim, Hee-Jae;Park, Jong-Wan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.04a
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    • pp.148-151
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    • 2000
  • $Mg_{2-2x}Ti_xO_2$ films were prepared by e-beam evaporation method to be used as possible substitutes for the conventional MgO protective layer. The oxygen content in the films and in turn, the ratio of metal to oxygen gradually increased with increasing the $TiO_2$ content in the starting materials. The pure MgO films exhibited the crystallinity with strong (111) orientation. The $Mg_{2-2x}Ti_xO_2$ films, however, had the crystallinity with (311) preferred orientation. When the $[TiO_2/(MgO+TiO_2)]$ ratios of 0.1 and 0.15 were used, the deposited films exhibited the secondary electron emission yields improved by 50% compared to that of the conventional MgO protective layer, which resulted in reduction in discharge voltage by 12%.

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Influence of DCS Post flow on the Properties of $\textrm{WSi}_{x}$ Thin films (DCS Post Flow가 $\textrm{WSi}_{x}$ 박막 특성에 미치는 영향)

  • 전양희;강성준;강희순
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.52 no.4
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    • pp.173-178
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    • 2003
  • In this paper, we studied the physical and electrical characteristics of $\textrm{WSi}_{x}$ thin film with respect to the adoption of the DCS (dichlorosiliane) post flow and the variation of deposition temperature. XRD measurements show that as deposited thin film has a hexagonal structure regardless of deposition Process. However, we find that the phase of thin film has changed to a tetragonal structure after the heat treatment at $680^{\circ}C$. Adoption of DCS post flow and increment of deposition temperature result in the increments of Si/W composition ratio. These conditions also result in the increment of sheet resistance by the amount 3.0~4.2$\Omega$/$\square$, but give the tendency in the decrement of stress by 0.27~0.3 E10dyne/$\textrm{cm}^2$. We also find that the contact resistance of word line and bit line interconnection was decreased by the amount 5.33~16.43$\mu$$\Omega$-$\textrm{cm}^2$, when applying DCS post flow and increasing deposition temperature.

Growth and characterization of MgZnO grown on R-plane sapphire substrate by plasma-assisted molecular beam epitaxy

  • Han, Seok-Kyu;Kim, Jung-Hyun;Hong, Soon-Ku;Lee, Jae-Wook;Lee, Jeong-Yong;Kim, Ho-Jong;Song, Jung-Hoon;Yao, Takafumi
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.11a
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    • pp.114-114
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    • 2009
  • ZnO has received considerable attention due to its potential applicability to optoelectronic devices such as ultraviolet-light emitting diodes (UVLEDs) and laser diodes (LDs). As well known, however, polar ZnO with the growth direction along the c-axis has spontaneous and piezoelectric polarizations that will result in decreased quantum efficiency. Recently, nonpolar ZnO has been studied to avoid such a polarization effect. In order to realize applications of nonpoar ZnO-based films to LEDs, growth of high quality alloys for quantum well structures is one of the important tasks that should be solved. $Mg_xZn_{1-x}O$ and $Cd_xZn_{1-x}O$ is ones of most promising alloys for this application because the alloys of ZnO with MgO and CdO provide a wide range of band-gap engineering spanning from 2.4 to 7.8 eV. In this study, we investigated on $Mg_xZn_{1-x}O$ films grown with various Mg/Zn flux ratios The films were grown on R-plane sapphire substrates by plasma-assisted molecular beam epitaxy (PAMBE). we investigated on $Mg_xZn_{1-x}O$ films grown with various Mg/Zn flux ratios. The films were grown on R-plane sapphire substrates by plasma-assisted molecular beam epitaxy (PAMBE). With the relatively low Mg/Zn flux ratios, a typical striated anisotropic surface morphology which was generally observed from the nonpolar (11-20) ZnO film on r-plane sapphire substrates. By increasing the Mg/Zn flux ratio, however, additional islands were appeared on the surface and finally the surface morphology was entirely changed, which was generally observed for the (0001) polar ZnO films by losing the striated morphology. Investigations by X-ray $\Theta-2{\Theta}$ diffraction revealed that (0002) and (10-11) ZnO planes are appeared in $Mg_xZn_{1-x}O$ films by increasing the Mg/Zn flux ratio. Further detailed investigation by transmission electron microscopy (TEM) and photoluminescence (PL) will be discussed.

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Utilizing Technology in Measurement System for Catenary Current: - Focusing on Testing Results for Kyoungbu High-speed Line in Korea - (조가선 전류 검측 시스템의 활용기술 연구 - 고속선 경부2단계 시험결과를 중심으로 -)

  • Park, Young;Jung, Hosung;Lee, Kiwon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.10
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    • pp.1465-1469
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    • 2013
  • The resent developed high speed train called HEMU-430X (Highspeed Electric Multiple Unit - 430km/h eXperiment) recorded a 421.4 km/h in Kyoungbu high speed line in Korea. A verity of measurement systems are used to check the performance between pantograph and catenary system. An innovative measurement system is adopted to check the current of catenary wire in the track side during HEMU-430X test running. This paper presents the measurement results of catenary current in kyoungbu high-speed line and describe its utilizing technology in the experimental results of catenary current. In order to analyze field testing results, the current ratio between contact and catenary current have been analyzed by means of Carson-Pollaczek equation. And the current wave forms between catenary and contact wire are presented based on the simulation results.

Effects of Plant Growth Regulators, Medium Salt Strength and Nitrogen Ratio on Cell Culture of Gymmema sylvestre (식물생장조절물질, 무기물 농도 및 질소원 비율이 Gymmma sylvestre 세포 배양에 미치는 영향)

  • Lee, Eun-Jung;Han, Eun-Joo;Paek, Kee-Yoeup
    • Journal of Plant Biotechnology
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    • v.33 no.2
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    • pp.105-110
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    • 2006
  • This study was carried out to investigate the effects of plant growth regulators, medium salt strength and nitrogen ratio on cell culture of Gymnema sylvestre. Cell growth was inhibited by 2,4-D higher than 1.0 mg L$^{-1}$, but not by kinetin lower than 0.5 mg L$^{-1}$. Maximal cell growth was obtained at 1.0 mg L$^{-1}$ 2,4-D and 0.1 mg L$^{-1}$ kinetin. Cell growth was greatest at 1x MS medium but high strength of MS medium inhibited cell growth due to low water potential in the medium. In $NH_4^+:NO_3^-$ ratio of 0:60 (i.e. 0.0 mM $^NH_4^+$ and 60.0 mM $NO_3^-$), cells growth was highest but cells were smaller and whiter compared with those in other $NH_4^+:NO_3^-$ ratio. Reduced cell growth was observed with continuous culture. These results suggested that optimal cell culture of G. sylvestre could be achieved with 1x MS medium with 20:40 ratio of $NH_4^+:NO_3^-$ supplemented with 1.0 mg L$^{-1}$ 2,4-D and 0.1 mg L$^{-1}$ kinetin.

Excimer Laser Annealing Effects of Double Structured Poly-Si Active Layer (이중 활성층(a-Si/a-SiNx)의 XeCl 엑시머 레이저 어닐링 효과)

  • 최홍석;박철민;전재홍;유준석;한민구
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.6
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    • pp.46-53
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    • 1998
  • A new method to form the double structured active layers of a-Si/a-SiN$_{x}$ of polycrystalline thin film transistor is proposed and poly-Si TFTs employed double structure active film are fabricated. Nitrogen ions were added to bottom amorphous silicon active film(a-SiN$_{x}$ ) and pure a-Si film deposition on a-SiN$_{x}$ was followed. The XeCl excimer laser was irradiated to crystallize double structure active film. The grain growth of upper a-Si film was also promoted in the double structured active layers of a-Si/a-SiN$_{x}$ due to the mitigation of solidification process of lower a-SiN$_{x}$ layer. Our experimental results show that the ratio of NH$_3$/SiH$_4$ is required to maintain below 0.11 for the reduction of contact resistance of n$^{+}$ poly-SiN$_{x}$ layer.r.

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Characteristics of Hazardous Volatile Organic Compounds (HVOCs) at Roadside, Tunnel and Residential Area in Seoul, Korea (서울시 도로변, 터널 및 주거지역 대기 중 유해 휘발성 유기화합물의 특성)

  • Lee, Je-Seung;Choi, Yu-Ri;Kim, Hyun-Soo;Eo, Soo-Mi;Kim, Min-Young
    • Journal of Korean Society for Atmospheric Environment
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    • v.27 no.5
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    • pp.558-568
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    • 2011
  • Hazardous volatile organic compounds (HVOCs) have been increasingly getting concern in urban air chemistry due to photochemical smog as well as its toxicity or potential hazards. In this study, we investigated their concentrations and the properties in tunnel, urban roadside and residential area. As a result, among 36HVOCs measured in this study, BTEX (benzene, toluene, ethylbenzene, xylene) and dichlorodifluoromethane, 1,2,4-trimethylbenzene, trichlorofluoromethane were detected above the concentration of $1{\mu}g/m^3$ in every sampling site and the most abundant compound was toluene. The other compounds were detected at trace level or below the detection limit. In addition, we found that three CFCs (chlorofluorocarbons), such as CFC-12, CFC-11, CFC-113, were persistently detected because of the emission in the past. Toluene to benzene ratio (T/B) at tunnel and roadside were calculated to be 4.3~5.3 and at residential area 15.4, suggesting that the residential area had several emission sources other than car exhaust. The ratio of X/E (m,p-xylene to ethylbenzene) ratio was calculated to be 1.8~2.1 at tunnel, 1.7 at roadside and 1.2 at residential area, which means this ratio reflected well the relative photochemical reactivity between these compounds. Good correlation between m,p-xylene and ethylbenzene ($r^2$ > 0.85) were shown in every study sites. This indicated that correlation between $C_2$-alkylbenzenes were not severely affected by 3-way catalytic converter. In this study, it was demonstrated that the concentration of benzene was very low, compared with national air quality standard (annual average of $5{\mu}g/m^3$). Its concentration were $2.52{\mu}g/m^3$ in roadside and $1.34{\mu}g/m^3$ in residential area. We thought this was the result of persistent policy implementation including the reduction of benzene content in gasoline enforced on January 1, 2009.

Synthesis and Characterization of Bandgap-modulated Organic Lead Halide Single Crystals

  • Park, Dae Young;Byun, Hye Ryung;Lee, A Young;Choi, Ho Min;Lim, Seong Chu;Jeong, Mun Seok
    • Journal of the Korean Physical Society
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    • v.73 no.11
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    • pp.1716-1724
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    • 2018
  • Single crystal of organic lead halide ($CH_3NH_3PbX_3$; $CH_3NH^+_3$ = methylammonium (MA), $X=Cl^-$, $Br^-$, $I^-$) is the best candidate for material intrinsic property studies due to no grain boundary and high crystal quality than the film having a lot of grain boundary and surface defects. The representative crystallization methods are inverse temperature crystallization (ITC) and anti-solvent vapor assisted crystallization (AVC). Herein, we report bandgap modulated organic lead halide single crystals having a bandgap ranging from ~ 2.1 eV to ~ 3 eV with ITC and AVC methods. The bandgap modulation was achieved by controlling the solvents and chloride-to-bromide ratio. Structural, optical and compositional properties of prepared crystals were characterized. The results show that the crystals synthesized by the two crystallization methods have similar properties, but the halide ratios in the crystals synthesized by the AVC method are controlled more quantitatively than the crystals synthesized by ITC.

Effect of Ar Flow Ratio on the Characteristics of Ga-Doped ZnO Grown by RF Magnetron Sputtering (마그네트론 스퍼터를 이용한 Ar 가스 유량 조절에 따른 GZO의 특성 변화)

  • Jeong, Youngjin;Lee, Seungjin;Son, Changsik
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.11a
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    • pp.62.1-62.1
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    • 2011
  • The structural, optical, and electrical properties of Ga-doped ZnO (GZO) thin films on glass substrates grown by radio-frequency(RF) magnetron sputtering were investigated. The flow ratio of Ar was varied as a deposition parameter for growing high-quality GZO thin films. The structural properties and surface morphologies of GZO were characterized by the X-ray diffraction. To analyze the optical properties of GZO, the optical absorbance was measured in the wavelength range of 300-1100 nm by using UV-VIS spectrophotometer. The optical transmittance, absorption coefficient, and optical bandgap energy of GZO thin films were calculated from the measured data. The crystallinity of GZO thin films is improved and the bandgap energy increases from 3.08 to 3.23eV with the increasing Ar flow ratio from 10 to 100 sccm. The average transmittance of the films is over 88% in the visible range. The lowest resistivity of the GZO is $6.215{\times}10^{-4}{\Omega}{\cdot}cm$ and the hall mobility increases with the increasing Ar flow ratio. We can optimize the characteristics of GZO as a transparent electrode for thin film solar cells by controlling Ar flow ratio during deposition process.

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An Experimental Study on the NH3-SCR of NOx over a Vanadium-based Catlayst (바나듐 계열 촉매를 통한 NOx의 NH3-SCR에 관한 실험적 연구)

  • Jeong, Hee-Chan;Sim, Sung-Min;Kim, Young-Deuk;Jeong, Soo-Jin;Kim, Woo-Seung
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.1
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    • pp.20-27
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    • 2012
  • The $NH_3$-SCR characteristics of $NO_X$ over a V-based catalyst are experimentally examined over a wide range of operating conditions, i.e., $170-590^{\circ}C$ and $30,000-50,000h^{-1}$, with a simulated diesel exhaust containing $NH_3$, NO, $NO_2$, $O_2$, $H_2O$, and $N_2$. The influences of the space velocity and oxygen concentration on the standard-SCR reaction are analyzed, and it is shown that the low space velocity and high oxygen concentration promote the SCR activity by ammonia. The best $deNO_X$ efficiency is obtained with a $NO_2/NO_X$ ratio of 0.5 because of an enhanced chemical activity induced by the fast-SCR reaction, while at the $NO_2/NO_X$ ratios above 0.5 the $deNO_x$ activity decreases due to the slow-SCR reaction. The oxidation of ammonia begins to take place at about $300^{\circ}C$ and the reaction products, such as $N_2$, NO, $NO_2$, $N_2O$, and $H_2O$, are produced by the undesirable oxidation reactions of ammonia, particularly at high temperatures above $450^{\circ}C$. Also, $NO_2$ decomposes to NO and $O_2$ at temperatures above $240^{\circ}C$. Therefore, $NO_2$ decomposition and ammonia oxidation reactions deteriorate significantly the SCR catalytic activity at high temperatures.