• Journal of The Korean Astronomical Society
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• v.39 no.4
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• pp.151-155
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• 2006

Long slit spectrometers are widely used in optical and infrared bands in astronomy. Absolute flux calibration for extended sources, however, is not straightforward, because a portion of the radiation energy from a flux calibration star is blocked by the narrow slit width. Assuming that the point spread function(PSF) of the star is circularly symmetric, we develop a robust method to extrapolate the detected stellar flux to the unobscured flux using the measured PSF along the slit-length direction. We apply this method to our long slit data and prove that the uncertainty of the absolute flux calibration is less than a few percents.

• Korean Journal of Optics and Photonics
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• v.3 no.4
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• pp.280-287
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• 1992

The nonlinear optical properties of semiconductors and semiconductor microstructures have been the subject of intense research, not only from a fundamental physics point of view, but also for their potential applications to future opto-electronic devices. In this paper, steady-state and time-resolved nonlinear optical spectroscopic techniques to investigate the microscopic world of semiconductor materials were briefly described.

• Archives of Pharmacal Research
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• v.27 no.12
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• pp.1216-1219
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• 2004

Spinoside, new coumaroyl flavone glycoside was isolated from the n-butanol fraction of the mathanolic extract of the whole plant of Amaranthus spinosus and assigned the structure 7-pcoumaroyl apigenin 4-O-${\beta}$ -D-glucopyranoside (1) on the basis of spectroscopic techniques including 1D and 2D NMR spectroscopy. In addition ${\alpha}$ - xylofuranosyl uracil (2), ${\beta}$ -D-ribofuranosyl adenine (3) and ${\beta}$ -sitosterol glucoside (4) have also been isolated for the first time from this species.

• Archives of Pharmacal Research
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• v.18 no.5
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• pp.361-363
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• 1995

Two furofuran lignans, sesamolin and sesangolin were isolated from the seeds of Sesamum indicum and S.angolense, respectively. Detailed analysis of the $^1H-and^{13}C-NMR$ spectra of these lignans was carried out by the application of two-dimensional $^1H-^1/H\; COSY\; and^1/H^{13}C$ multiple-bond, multiple-quantum spectroscopic correlation techniques.

• Journal of the Korean Chemical Society
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• v.62 no.2
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• pp.87-92
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• 2018

A series of pyrimidine annulated dihydropyrano[2, 3-c]pyrazole derivatives were synthesized and screened for their antimicrobial activity. The precursor, dihydropyrano[2, 3-c]pyrazole was synthesised under catalyst free condition using PEG-400 as reaction medium which facilitated improved yield compared to base catalyzed reaction. Wide scope of substrates, simple workup procedure and high yield even in the absence of catalyst are the major highlights of the protocol. Dihydropyrano[2, 3-c]pyrazoles on condensation with formic acid formed pyrimidine annulated dihydropyrano[2, 3-c]pyrazole derivatives. All the products are characterized using FTIR, $^1H-NMR$ and $^{13}C-NMR$ spectroscopic techniques. The molecules have shown good to moderate activity as antimicrobial agents when compared to the standard drug ciprofloxacin.

• Archives of Pharmacal Research
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• v.19 no.5
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• pp.406-410
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• 1996

The flowers of Chrysanthemum boreale afforded handelin, a unique guaianolide dimer and a mixture of n-hydrocarbons and n-hydrocarbon alcohols in addition to b-sitosterol and b-sitosterol glucoside. Detailed analysis of the $^{1}H$- and $^{13}C$-NMR spectra of handelin was carried out by the application of two-dimensional $^{1}H-^{1}H$-COSY and $^{1}H$- $^{13}C$ multiple-bond, multiple-quantum spectroscopic correlation techniques. Handelin was inactive in the in vitro anti-tumor activity.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.1022-1026
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• 2011

The syntheses of DTPA-bis(amide) conjugates of phosphonated cyclohexane moieties (5a-d) and their Gd(III) complexes of the type $[Gd(L)(H_2O)]{\cdot}nH_2O$ (6a-d; L = 5a-d) are described. All new compounds have been characterized by microanalysis and spectroscopic techniques. High $r_1$ relaxivities of aqueous solutions of 6a-d are observed to be in the range of $10.7-18.3\;mM^{-1}sec^{-1}$, which compare much better than that of $Omniscan^{(R)}$ ($r_1=3.90\;mM^{-1}sec^{-1}$).

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1077-1079
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• 2009

To minimize the variance in the quantification of solid-state phases in powder samples, gently placing polycrystalline samples one next to another directly in a sample holder is better than trying to mix them homogeneously prior to transferring to a sample holder. However, the solid-state cross polarization-magic angle spinning (CP-MAS) nuclear magnetic resonance (NMR) spectroscopy results demonstrated that it is essential in this sampling method to place all the samples in the location of consistent signal sensitivity. The same sampling method may be employed in other spectroscopic quantification techniques of solid-state phases if the method to limit the sample to the location with uniform signal sensitivity in the sample holder is adapted to each technique.

• Journal of the Korean Ceramic Society
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• v.54 no.5
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• pp.388-394
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• 2017

Here, utilizing rhodamine B (RhB) as standard color dye, we examined the photo degradation proficiency of $Ag_2Se-Graphene-TiO_2$ nanocomposites under visible light irradiation; samples were prepared by ultrasonication techniques and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopic investigation and UV-Vis absorbance spectra examination. Our outcomes demonstrate that the $Ag_2Se-G-TiO_2$ nanocomposite showed significant photodegradation efficiency as compared with those of $TiO_2-G$ and $Ag_2Se-G$, with around 85.2% of Rhodamine B (RhB) degraded after 180 min. It is concluded that the $Ag_2Se-G-TiO_2$ nanocomposite is a competent candidate for dye pollutants.

• Journal of The Korean Astronomical Society
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• v.37 no.2
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• pp.87-90
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• 2004

Spectrophotometry of the night sky over Mount Bohyun is presented for the nearly entire visible wavelengths of $3600{\~}$8600{\AA}$. The data was obtained under moonless clear sky in February 2004 with the 1.8-m telescope and the long slit spectrograph. The sky spectrum shows a number of strong emission lines originated from light pollution, especially due to high pressure sodium lamps. When compared to the night sky of Kitt Peak, our sky continuum is 1 to 2 magnitude brighter at all wavelengths, the worst being around the broad emission region near 6000${\AA}$. The night sky spectrum presented here with almost complete line identifications is a useful reference for arc-independent wavelength calibrations to check the gravity flexure of the spectrograph and the wavelength shift between FeNeArHe arc frames and science frames.