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        검색결과 72

        21.
        2011.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the present study, potassium and caesium doped Ag/ catalysts were synthesized by simple wet impregnation method and evaluated for selective catalytic reduction (SCR) of NOx using methane. TEM analysis and diffraction patterns demonstrated the finely dispersed Ag particles. BET surface measurements reveal that the prepared materials have moderate to high surface area and the metal amount found from ICP analysis was well matching with the theoretical loadings. The synthesized K-Ag/ and Cs-Ag/ catalysts exhibited a promotional effect on deNOx activity in the presence of and . The long-term isothermal studies at under oxygen rich condition showed the superior catalytic properties of the both alkali promoted samples. The crucial catalytic properties of materials are attributed to NO adsorption properties detected by the NO TPD.
        4,000원
        25.
        2010.09 구독 인증기관 무료, 개인회원 유료
        본 논문에서는 JPEG 코딩에 따른 잡음에 대한 효과적인 저감 방법을 제안한다. JPEG 코딩에 의한 대표적인 잡음으로는 블록 잡음과 링깅 잡음을 들 수 있다. 이와 같은 잡음들을 저감하기 위한 다양한 방법들이 제안된 바 있다. 하지만, 대부분의 기존 방법들은 영상 내부의 모든 블록을 처리함에 따라 과도한블러링 뿐만 아니라 처리시간의 증가와 메모리 양의 증가를 초래한다. 본 논문에서는잡음의 검출과 저감을 위한 효과적인 방법을 제안한다. 제안하는 방법에서는 모든 블록을 사용하지 않기 때문에 계산량 및 메모리 양을 감소시킨다. 검출 과정은 영상의 DCT 계수만을 사용하여 주파수 영역에서 수행된다. 다양한 실험이 수행되었으며 기존의 방법의 결과와 비교하였다. 실험 결과 제안하는 방법의 성능을 확인할 수 있었다.
        4,800원
        26.
        2010.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigate ρ Pup using the high resolution spectral observations taken from the VLT archive and observations at a 1.8m-Korean telescope with BOES spectrograph. The atmospheric parameters are determined using the iron-line abundance analysis. We derive an effective temperature value of Teff=6890±250K, surface gravity of log g=3.28±0.3 dex, microturbulent velocity of vmicro=4.1±0.4 km s-1, and the iron abundance of log N=7.82±0.15. The projected rotational velocity of the star is close to v sin i =3.5km s-1. Asymmetric line profiles in the observed spectra and variation of this asymmetry with time show that both strong radial pulsation and weak non-radial pulsations are present in ρ Pup
        4,000원
        28.
        2009.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We measured the non-carbon content of single-walled carbon nanotubes (SWCNTs) in SWCNT soot using thermogravimetric analysis. The weight increased percentage by the oxidation of metal in the raw soot is well obtained by TGA graph which was confirmed with ICP-AES, XRD, and XPS. This work will be very useful for the purity precise evaluation of SWCNT with UN-vis-NIR spectroscopy.
        3,000원
        32.
        2006.09 구독 인증기관·개인회원 무료
        Li reacts with N2 at room temperature. In order to activate Li, the mechanical milling of Li with stable metal oxide, namely, Al2O3 and MgO, using a high energy vibrating ball mill was performed. In the case of Li-MgO system, it reacts with N2, but hardly reacts with O2. The reaction with N2 generally produces Li3N, while for some vigorous reactions the Mg3N2 is produced as the major phases. In the case of Li-Al2O3 system, reactivities with both N2 and O2 are high. The difference is explained in terms of the reaction mechanism and the Li state.
        33.
        2006.09 구독 인증기관·개인회원 무료
        Ti-Cu-Ni-Sn quaternary amorphous alloys of Ti50Cu32Ni15Sn3, Ti50Cu25Ni20Sn5, and Ti50Cu23Ni20Sn7 composition were prepared by mechanical alloying in a planetary high-energy ball-mill (AGO-2). The amorphization of all three alloys was found to set in after milling at 300rpm speed for 2h. A complete amorphization was observed for Ti50Cu32Ni15Sn3 and Ti50Cu25Ni20Sn5 after 30h and 20h of milling, respectively. Differential scanning calorimetry analyses revealed that the thermal stability increased in the order of Ti50Cu32Ni15Sn3, Ti50Cu25Ni20Sn5, and Ti50Cu23Ni20Sn7.
        34.
        2006.09 구독 인증기관·개인회원 무료
        Titinium carbide (TiCx) was produced by self-propagating high temperature synthesis (SHS) method. The morphology and non-stoichiometric number of the SHS product were observed by scanning electron microscopy and neutron diffractometry, respectively. Tubular titanium carbide with hole inside was formed with different non-stoichiometric number (x), which value increased with combustion temperature.
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