• Title, Summary, Keyword: spectra

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Symmetry and Spectra of Complexes of Azo-Substituted Copper Phthalocyanine (Copper Phthalocyanine과 그 Azo 置換錯鹽들의 對稱과 Spectra)

  • Cho Nam-Sook;Kim Ki-Hwan;Hahn Chi-Sun
    • Journal of the Korean Chemical Society
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    • v.16 no.6
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    • pp.378-384
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    • 1972
  • The UV absorption spectra of the copper phthalocyanine and its azo derivatives in pyridine have been examined on the basis of symmetry operation, ligand field theory and molecular orbital consideration. The above treatment was also employed to determine the structure of the synthesized complexes.

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Stabilizing Linear Prediction for Discrete Harmonic Spectra of Audio Signals

  • Nam, Seung-Hyon;Kyeongok Kang;Hong, Jin-Woo
    • The Journal of the Acoustical Society of Korea
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    • v.20 no.4E
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    • pp.39-44
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    • 2001
  • We investigate the numerical instability of linear prediction for discrete harmonic spectra of audio signals. It is identified that the eigenvalue spread is very large when discrete harmonic spectra are confined only in a lower part of the entire signal bandwidth. A simple method that redefines the sampling frequency and associate harmonic frequencies is proposed to improve the numerical stability. Simulation results using real audio signals indicate its superior stabilizing ability and improved accuracy in the discrete spectral estimation for both LP and DAP.

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Gas Phase Optoacoustic Spectra and Raman Spectra of Some Chlorinated Pollutants

  • Joong-Gil Choi;Jin-soo Hwang;Paeng Ki-Jung;Gerald J. Diebold
    • Bulletin of the Korean Chemical Society
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    • v.14 no.1
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    • pp.127-131
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    • 1993
  • Laser optoacoustic technique has been employed to obtain the gas phase absorption spectra of 1-chloronaphthalene, 3-chlorobiphenyl, and 2,5,2'-trichlorobiphenyl in conjunction with a gas chromatograph and a Helmholtz resonator at the various $CO_2$ laser wavelengths. Raman spectra of 1-chloronaphthalene, 4-chlorobiphenyl, and 4,4'-dichlorobiphenyl in condensed phase have been also obtained. The optoacoustic measurement of the infrared absorption in gas phase has been shown to be of value in monitoring the environmental pollutants.

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Characteristics of the Low Frequency Sequence Bands Observed in the Vibronic Emission Spectra of the Jet Cooled p-Fluorobenzyl Radical in the $D-1\rightarrow D_0$ Transition

  • 백대열;이상국
    • Bulletin of the Korean Chemical Society
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    • v.19 no.12
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    • pp.1359-1363
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    • 1998
  • The p-fluorobenzyl radical was generated from the p-fluorotoluene and vibronically excited in a corona excited supersonic expansion with inert buffer gases. The vibronic emission spectra of the jet cooled p-fluorobenzyl radical in the D1 → D0 transition have been observed in the visible region. The spectra exhibit several low frequency sequence bands in the vicinity of the every strong vibronic band. The characteristics of the sequence bands have been examined by varying the experimental conditions such as carrier gas and nozzle size to identify the origin of the transition in the spectra.

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A Practical Method to Correct the Saturation Effect in XMCD Spectra

  • Kim, J.Y.
    • Journal of Magnetics
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    • v.13 no.3
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    • pp.85-87
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    • 2008
  • I report a simple method to correct the saturation effect in absorption spectra measured in total electron yield (TEY) mode. It does not require additional measurements of the X-ray penetration depth. In order to check the reliability of the method, X-ray magnetic circular dichroism (XMCD) spectra for polycrystalline Fe were measured at two different incident angles, and then processed with the method. The two resultant XMCD spectra were identical, and their sum rule analysis produced the ratios of orbital magnetic moment to spin magnetic moment, which were very close to the well-known value.

STANDARIZING THE EXTRATERRESTRIAL SOLAR IRRADIANCE SPECTRUM FOR CAL/VAL OF GEOSTATIONARY OCEAN COLOR IMAGER (GOCI)

  • Shanmugam, Palanisamy;Ahn, Yu-Hwan
    • Proceedings of the KSRS Conference
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    • v.1
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    • pp.86-89
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    • 2006
  • Ocean color remote sensing community currently uses the different solar irradiance spectra covering the visible and near-infrared in the calibration/validation and deriving products of ocean color instruments. These spectra derived from single and / or multiple measurements sets or models have significant discrepancies, primarily due to variation of the solar activity and uncertainties in the measurements from various instruments and their different calibration standards. Thus, it is prudent to examine model-to-model differences and select a standard reference spectrum that can be adopted in the future calibration and validation processes, particularly of the first Geostationary Ocean Color Imager (GOCI) onboard its Communication Ocean and Meterological Satellite (COMS) planned to be launched in 2008. From an exhaustive survey that reveals a variety of solar spectra in the literature, only eight spectra are considered here seeing as reference in many remote sensing applications. Several criteria are designed to define the reference spectrum: i.e., minimum spectral range of 350-1200nm, based completely or mostly on direct measurements, possible update of data and less errors. A careful analysis of these spectra reveals that the Thuillier 2004 spectrum seems to be very identical compared to other spectra, primarily because it represents very high spectral resolution and the current state of the art in solar irradiance spectra of exceptionally low uncertainty ${\sim}0.1%.$ This study also suggests use of the Gueymard 2004 spectrum as an alternative for applications of multispectral/multipurpose satellite sensors covering the terrestrial regions of interest, where it provides spectral converge beyond 2400nm of the Thuillier 2004 spectrum. Since the solar-activity induced spectral variation is about less than 0.1% and a large portion of this variability occurs particularly in the ultraviolet portion of the electromagnetic spectrum that is the region of less interest for the ocean color community, we disregard considering this variability in the analysis of solar irradiance spectra, although determine the solar constant 1366.1 $Wm^{-2}$ to be proposed for an improved approximation of the extraterrestrial solar spectrum in the visible and NIR region.

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2,4,6-Triamino-1,3,5-triazin-1-ium Acetate Acetic Acid Solvate Monohydrate. Infrared and Raman Spectra

  • Marchewka, M.K.
    • Bulletin of the Korean Chemical Society
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    • v.25 no.4
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    • pp.466-470
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    • 2004
  • The crystals of the new melaminium salt, i.e. melaminium acetate acetic acid solvate monohydrate, $C_3H_7N_6^+ {\cdot}CH_3COO^- {\cdot}CH_3COOH{\cdot}H_2O$, were obtained by the slow evaporation of an aqueous solution at room temperature. Powder infrared and Raman spectra were measured and interpreted. The vibrational spectra in the region of internal vibrations of ions corroborate structural data recently published by Perpetuo and Janczak.$^1$ Some spectral features of this new crystal are referred to corresponding one for melamine crystal as well as other melamine complexes in crystalline form. Hydrogen-bonded network present in the crystal gives notable vibrational effect.

A study on the Spectra reinforcement composite of its ballistic performance (방탄용 Spectra 섬유 강화 복합재료에 관한 연구)

  • 강은영;윤영기;윤희석
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.83-86
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    • 2001
  • This paper presents an investigation of the contribution of fibers in energy absorption during impact and the effect of resin types on properties of the high strength polyethylene (Spectra-900 PE) composite. In high strength polyethylene fiber, main impact energy absorbing mechanism was tensile breakage and deformation of fiber. Two types of resin were examined : Unsaturated polyester (UP) and Epoxy. Tensile and 3-point bending test have been performed to investigate the changes of mechanical properties. In tensile and flexural testes, the Spectra Composite prepregged with UP showed higher properties than Spectra Composite prepregged with epoxy.

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Studies on the Chemical Components of Fruits of Forsythia Koreana NAKAI (II) Ocurrence of betaine in the fruits of Forsythia Koreana (Forsythia koreana NAKAI 씨 (토연교)의 성분에 관한 연구 (II) (Betaine의 분리 및 확인))

  • Cang Sae Hee;Kim Jae Soon;Huh Tae Soung
    • Journal of the Korean Chemical Society
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    • v.15 no.1
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    • pp.1-3
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    • 1971
  • The methanol extract of the fruits of Forsythia Koreana NAKAI was separated and purified. The quaternary base chloride was obtained. Through the mass spectrogram, ultraviolet spectra, infrared spectra, elemental analysis and qualitative tests it was identified as betaine hydrochloride.

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Electronic Spectra and Quenching of Dimethylanilines (Dimethylanline의 Electronic Spectra와 消光)

  • Jung, Kyung-Hoon;Lee, Ik-Choon
    • Journal of the Korean Chemical Society
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    • v.8 no.4
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    • pp.158-163
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    • 1964
  • Electronic spectra and quenching constants for ten N,N-dimethylanilines (DMA) have been determined. The $250m{\mu}$ absorption band (C band) of DMA was shown to be mainly responsible for the quenching. This band was confirmed as an $n{\to}{\pi}^{\ast}$ band through substituent and medium effects on the spectra shifts. The energy absorbed by this band then transfers to triplet and down to the lowest triplet state, $^{3}La$, where the energy is lost by non-radiative collisions.

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