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        검색결과 145

        61.
        2010.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In order to study properties of the pulsation in the infrared emission for long period variables, we collect and analyze the infrared observational data at L band for 12 OH/IR. The observation data cover about three decades including recent data from the ISO and Spitzer. We use the Marquardt-Levenberg algorithm to determine the pulsation period and amplitude for each star and compare them with results of previous investigations at infrared and radio bands. We obtain the relationship between the pulsation periods and the amplitudes at L band. Contrary to the results at K band, there is no difference of the trends in the short and long period regions of the period-luminosity relation at L band. This may be due to the molecular absorption effect at K band. The correlations among the L band parameters, IRAS [12-25] colors, and K band parameters may be explained as results of the dust shell parameters affected by the stellar pulsation. The large scatter of the correlation could be due to the existence of a distribution of central stars with various masses and pulsation modes.
        4,200원
        64.
        2009.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        6,700원
        65.
        2009.10 구독 인증기관·개인회원 무료
        66.
        2009.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We fabricated thermally evaporated 30 nm-Ni/(20 nm or 60 nm)a-Si:H/Si films to investigate the energy-saving property of silicides formed by rapid thermal annealing (RTA) at temperatures of 350˚C, 450˚C, 550˚C, and 600˚C for 40 seconds. A transmission electron microscope (TEM) and a high resolution X-ray diffractometer (HRXRD) were used to determine the cross-sectional microstructure and phase changes. A UVVIS-NIR and FT-IR (Fourier transform infrared spectroscopy) were employed for near-IR and middle-IR absorbance. Through TEM and HRXRD analysis, for the nickel silicide formed at low temperatures below 450˚C, we confirmed columnar-shaped structures with thicknesses of 20~30 nm that had δ-Ni2Si phases. Regarding the nickel silicide formed at high temperatures above 550˚C, we confirmed that the nickel silicide had more than 50 nm-thick columnar-shaped structures with a Ni31Si12 phase. Through UV-VIS-NIR analysis, nickel silicide showed almost the same absorbance in the near IR region as well as ITO. However, in the middle IR region, the nickel silicides with low temperature showed similar absorbance to those from high temperature silicidation.
        4,000원
        67.
        2008.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We have fabricated and evaluated newNew high high-efficiency green green-light light-emitting phosphorescent devices with an emission layer of [TCTA/TCTA1/3TAZ2/3/TAZ] : Ir(ppy)3 were fabricated and evaluated, and compared the electroluminescence characteristics of these devices were compared with the conventional phosphorescent devices with emission layers of (TCTA1/3TAZ2/3) : Ir(ppy)3 and (TCTA/TAZ) : Ir(ppy)3. The current density, luminance, and current efficiency of the a device with an emission layer of (80Å-TCTA/90˚Å-TCTA1/3TAZ2/3/130Å-TAZ) : 10%-Ir(ppy)3 were 95 mA/cm2, 25000 cd/m2, and 27 cd/A at an applied voltage of 10 V, respectively. The maximum current efficiency was 52 cd/A under the a luminance value of 400 cd/m2. The peak wavelength and FWHM (FWHM (full width at half maximum) in the electroluminescence spectral were 513 nm and 65 nm, respectively. The color coordinate was (0.30, 0.62) on the CIE (Commission Internationale de I'Eclairage) chart. Under the a luminance of 15000 cd/m2, the current efficiency of the a device with an emission layer of (80Å-TCTA/90Å-TCTA1/3TAZ2/3/130Å-TAZ) : 10%-Ir(ppy)3 was 34 cd/A, which has beenshowed an improvement of improved 1.7 and 1.4 times compared to those of the devices with emission layers of (300Å-TCTA1/3TAZ2/3) : 10%-Ir(ppy)3 and (100Å-TCTA/200Å-TAZ) : 10%-Ir(ppy)3, respectively.
        4,000원
        68.
        2008.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        High-efficiency phosphorescent organic light emitting diodes using TCTA-TAZ as a double host and Ir(ppy)3 as a dopant were fabricated and their electro-luminescence properties were evaluated. The fabricated devices have the multi-layered organic structure of 2-TNATA/NPB/(TCTA-TAZ) : Ir(ppy)3/BCP/SFC137 between an anode of ITO and a cathode of LiF/AL. In the device structure, 2-TNATA[4,4',4"-tris(2-naphthylphenyl-phenylamino)-triphenylamine] and NPB[N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] were used as a hole injection layer and a hole transport layer, respectively. BCP [2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline] was introduced as a hole blocking layer and an electron transport layer, respectively. TCTA [4,4',4"-tris(N-carbazolyl)-triphenylamine] and TAZ [3-phenyl-4-(1-naphthyl)-5-phenyl-1,2,4-triazole] were sequentially deposited, forming a double host doped with Ir(ppy)3 in the [TCTA-TAZ] : Ir(ppy)3 region. Among devices with different thickness combinations of TCTA (50 Å-200 Å) and TAZ (100 Å-250 Å) within the confines of the total host thickness of 300 Å and an Ir(ppy)3-doping concentration of 7%, the best electroluminescence characteristics were obtained in a device with 100 Å-think TCTA and 200 Å-thick TAZ. The Ir(ppy)3 concentration in the doping range of 4%-10% in devices with an emissive layer of [TCTA (100 Å)-TAZ (200 Å)] : Ir(ppy)3 gave rise to little difference in the luminance and current efficiency.
        4,000원
        70.
        2007.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We present the sensitivity calculation results for observing the Cosmic Infrared Background (CIRB) by the Multi-purpose IR Imaging System (MIRIS), which will be launched in 2010 as a main payload of the Science and Technology Satellite 3 (STSAT-3). MIRIS will observe in I ( 0.9∼1.2um) and H (1.2∼2.0um) band with a 4×4 degree field of view to obtain the large scale structure ( ∼3 degree) of the CIRB. With the given specifications of the MIRIS, our sensitivity calculation results show that the MIRIS has a detection limit of ∼9nWm−2sr−1 (I band) and ∼6nWm−2sr−1 (H band), which is appropriate to observe the large scale structure of CIRB.
        4,000원
        79.
        2005.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Fatty acid compositions of the seed oils of P. schinseng, A. continentalis and A. sessiliflorus, were analyzed by gas chromatography (GC) equipped with a capillary column. A large unusual peak was observed just before the peak corresponding to oleic acid (cis-9-C18:1). This unknown fatty acid was isolated by silver ion chromatography and then derivatized into the picolinyl ester. The mass spectrum of the picolinyl ester showed molecular ion at m/z=373 with other diagnostic ions such as m/z=178, 218, 232, 246, 274, 288, 302 and 344. Characteristic absorption peaks at 720 cm-1, 1640 cm-1 and 3010 cm-1 in IR spectrum indicated the presence of cis-configurational double bond in the molecule. The 1H-NMR spectrum of this acid gave two quintets centered at δ1.638 (2H, C-3) and δ1.377 (2H, C-4), and two multiplets centered at δ2.022~2.047 (2H, C-5) and δ2.000~2.022 (2H, C-8), and multiplet signals of olefinic protons centered at δ5.3015~5.3426 (C-6, J=9.5 Hz) and δ 5.3465~5.3877 (C-7, J=9.5 Hz). The 13C-NMR spectrum showed 18 carbon resonance signals including an overlapped signal at δ29.7002 for C-12 and δ29.6520 for C-13 (or they can be reversed), and other highly resolved signals at δ33.950, δ24.558, δ26.773 and δ27.205 due to C-2, C-3, C-5 and C-8 of a δ6-octadecenoic acid, respectively. From analysis results this unknown fatty acid could be identified as cis-6-octadecenoic acid. The seed oils of P. schinseng and A. sessiliflorus contained petroselinic acid (59.7%, 56.0%), oleic acid (18.3%, 6.1%) and linoleic acid (16.2%, 30.4%) with small amount of palmitic acid (3.0%, 3.1%) while the seed oil of A. continentalis comprised mainly oleic acid (30.2%), petroselinic acid (29.0%), linoleic acid (24.1%) and palmitic acid (13.1%).
        4,000원
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