• Title/Summary/Keyword: Reduction atmosphere

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Climate Prediction by a Hybrid Method with Emphasizing Future Precipitation Change of East Asia

  • Lim, Yae-Ji;Jo, Seong-Il;Lee, Jae-Yong;Oh, Hee-Seok;Kang, Hyun-Suk
    • The Korean Journal of Applied Statistics
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    • v.22 no.6
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    • pp.1143-1152
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    • 2009
  • A canonical correlation analysis(CCA)-based method is proposed for prediction of future climate change which combines information from ensembles of atmosphere-ocean general circulation models(AOGCMs) and observed climate values. This paper focuses on predictions of future climate on a regional scale which are of potential economic values. The proposed method is obtained by coupling the classical CCA with empirical orthogonal functions(EOF) for dimension reduction. Furthermore, we generate a distribution of climate responses, so that extreme events as well as a general feature such as long tails and unimodality can be revealed through the distribution. Results from real data examples demonstrate the promising empirical properties of the proposed approaches.

A Fabrication and Characteristics of GaInAs/InP PIN Phtodiode Grown by LPE (LPE에 의한 GaInAs/InP PIN Photodiode의 제작 및 특성)

  • 박찬용;남은수;박경현;김상배;박문수;이용탁;홍창희
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.5
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    • pp.737-746
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    • 1990
  • Ga0.47In0.53As PIN photodiodes(PD) having various areas have been fabricated by liquid phase epitaxial techniques. Ternary melt has been baked out at 675\ulcorner in H2 atmosphere for 20 hours before growth, which resulted in reduction of background carrier concentration of grown epi-layer. Also, lattice mismatch has been controlled within 0.01%. The room temperature performance of 10**-4cm\ulcornerarea PIN PD at a bias voltage of -5V were` quantum efficiency(with no antireflection coating)=60% for 1.3\ulcorner light source, dark current\ulcorner5nA, and capacitance\ulcornerpE. Frequency response measurement of packaged PIN PD has shown that cut-off frequency (f-3dB) was 961MHz. This PD has shown a good eye pattern when it was incorporated in a 565Mbps optical receiver.

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Analysis of Domestic and Abroad R&D Trends for Greenhouse Gas Reduction (온실가스 저감을 위한 국내외 R&D 및 정책 동향)

  • Lee, Sang Hun;Seo, Bong Guk;Lee, Gyu Ho
    • Journal of Environmental Science International
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    • v.13 no.9
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    • pp.845-853
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    • 2004
  • Recently many countries agreed to reduce emissions of greenhouse gases into the atmosphere or at least to keep them at the current level at the Kyoto Protocol. Carbon dioxide has been proven to be 80% of greenhouse gases, contributing to the increase of the earth's surface temperature. It is reported that half of the $CO_2$ emissions are produced by industry and power plants using fossil fuels. In this article, we review and analysis domestic and abroad R & D policy trends relating to UN framework convention on climate change(UNFCCC).

Synthesis and Luminescent Property Investigation of the $Lu_3Al_5O_{12}$:Ce for the White LEDs

  • Lee, Seung-Jae;Park, Joung-Kyu;Bae, Pan-Kee;Kim, Chang-Hae;Chang, Hyun-Ju;Kim, Yong-Rok
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.591-593
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    • 2008
  • In this report, cerium doped lutetium aluminate ($Lu_3Al_5O_{12}$:Ce) phosphor has been synthesized by the solid state method under reduction atmosphere with mixture gas. The prepared phosphor shows a main luminescent peak at 555nm. Consequently, this phosphor is possible to be applicable to white LED lamp by InGaN chips.

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AC Conductivity and Dielectric Constant of Ni-MgO Composites (Ni-MgO 복합재료의 전기전도도와 유전상수)

  • ;Eric R. Kreidler
    • Journal of the Korean Ceramic Society
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    • v.28 no.4
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    • pp.329-337
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    • 1991
  • The Ni-MgO composites were prepared by coprecipitation of NiO-MgO solid solutions and their selective reduction in a hydrogen atmosphere. We report on the measurements of both ac conductivity $\sigma$ ($\omega$, f) and dielectric constant $textsc{k}$'($\omega$, f) for the Ni-MgO composites in the frequency range from 10 Hz to 10 MHz at room temperature. The frequency exponents of conductivity and dielectric constant, x and y, are found to be x=0.98$\pm$0.05 and y=0.05$\pm$0.01. These results are in good agreement with a general scaling relation $\chi$-y=1, although these values are different from the theoretical predications. The dielectric constant exponent ($textsc{k}$' f-fc -s) is found to be s=0.62$\pm$0.07 with estimated percolation threshold fc=0.20$\pm$0.02.

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Study of the Reaction between the Dielectric and the Electrode during the Manufacturing of the Ceramic Capaciitor (요업콘덴사 제조에 있어서의 과전체와 전기물질간의 반응검사)

  • 김기호
    • Journal of the Korean Ceramic Society
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    • v.21 no.1
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    • pp.60-66
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    • 1984
  • During the metallization in the manufacturing of the ceramic capacitor at the boundary layer between Pd or Pt electrode and $BaTiO_3$-dielectric reactions were analysed. For the study of the reaction Electron Spin Resonance (ESR) Method was used. With the aid of ESR an increased of the concentration of the paramagnetic $Ti^{3+}$-Centers on the metallizing process could be seen. It meaned a reduction effect although the metallization was accomplished under oxidation atmosphere. Therefore it could be regarded as a reaction at the boundary layer. In order to investigate the reaction ad double octahedral model was compared and the increase of the $Ti^{3+}$-concentration was studied.

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Synthesis of the $CaGa_2S_4:Eu^{2+}$ phosphors and Application in White LEDs

  • Kim, Jae-Myung;Kim, Kyung-Nam;Park, Joung-Kyu;Kim, Chang-Hae;Jang, Ho-Gyeom
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07b
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    • pp.1623-1626
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    • 2005
  • The thiogallate phosphors which are well known for a long time as phosphor materials for CRT or EL device were reported. Those have high luminescent properties at long-wavelength region. Among those phosphors, the samples with divalent europium doped CaGa2S4 were prepared by a simple process under the reduction atmosphere $(5%\;H_2/\;95%\;N_2)$ without toxic gas such as H2S or CS2. The prepared phosphor shows a higher luminescent efficiency (about 120%) than that of $YAG:Ce^{3+}$ phosphor. Consequently, this phosphor is possible to be applicable to white LED lamp because of the high luminescent efficiency.

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Mechanical characteristic of overhead transmission lines by forest fires (화염에 노출된 가공송전선의 기계적.재료적 특성 검토)

  • Kang, J.W.;Jang, T.I.;Kim, B.K.;Park, C.G.;Bang, H.K.
    • Proceedings of the KIEE Conference
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    • 2002.07a
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    • pp.339-341
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    • 2002
  • The remaining life of ACSR exposed to the atmosphere for a long period may rely on deterioration caused by environmental indices such as atmospheric corrosion, galvanic corrosion, crevice corrosion and fatigue corrosion. One of reduction of useful life in overhead transmission lines built on the ridge of mountain is often caused by forest fires. This paper deals with investigation of strength deterioration performance of ACSR due to fires through several testing and analyzing data for both tension load and material analysis. Test samples are ACSR $480[mm^2]$ conductors, which are artificially fired to regular durations. As a result, it can be verified that tension load of ACSR are reduced by increasing fro duration. Hence, it is obvious that ACSR due to forest fires may lead to mechanical deterioration.

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Synthesis of ZnO Powder by Precipitation method and Its Cathodoluminescence Properties (침전법에 의한 ZnO 분체합성 및 그 형광특성)

  • 김봉철;박지훈;신효순;이석기;이병교
    • Journal of the Korean Ceramic Society
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    • v.35 no.2
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    • pp.107-114
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    • 1998
  • ZnO powder as phosphor was prepared by precipitation method with zinc acetate and ammonia solution and the size and shapes of precipitates were examined with variation of pH and concentration of solution. Its cathodoluminesence properties was evaluated with various heat tratment condition. Optimum con-dition for uniform precipitates was 11.8 of pH and 0.4M of concentration. ZnO:Zn phosphor was obtained by heat treatment of precipitates in reduction atmosphere using ZnS powder. With addition of 20wt% ZnS and 1 hour firing at 1000$^{\circ}C$ the highest cathodoluminescence was obtained.

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Synthesis ofSialon-SiC Composite Powder from Alkoxides and the Powder Properties(I) (알콕사이드로부터 Sialon-SiC계 복합분말의 합성과 분말특성(I))

  • 전명철;이홍림
    • Journal of the Korean Ceramic Society
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    • v.27 no.2
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    • pp.265-273
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    • 1990
  • Fine Si-Al-OH-C coprecipitate powders were prepared from Si(OC2H5)4, Al(i-OC3H7)3, and carbon black by a hydrolysis method before fabrication of Sialon-SiC composite powder by carbothermal reduction at 1350$^{\circ}C$ for 10h under N2/H2 mixed atmosphere. The characterization of the synthesized Sialon-SiC composite powders was performed using XRD, BET, SEM, TEM and particle size analysis methods. The average particle size and specific surface area of the synthesized Sialon-SiC composite powder were 0.13$\mu\textrm{m}$ and 20.1㎡/g, respectively when Z=1 and N2 : H2=50 : 50.

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