• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.68.3-69
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• 2020

We develop a series of N-body data challenges, functional to the final analysis of the extended Baryon Oscillation Spectroscopic Survey (eBOSS) Data Release 16 (DR16) galaxy sample, primarily based on high-fidelity catalogs constructed from the Outer Rim simulation. We generate synthetic galaxy mocks by populating Outer Rim halos with a variety of halo occupation distribution (HOD) schemes of increasing complexity, spanning different redshift intervals. We then assess the performance of three complementary redshift space distortion (RSD) models in configuration and Fourier space, adopted for the analysis of the complete DR16 eBOSS sample of Luminous Red Galaxies (LRGs). We find that all the methods are mutually consistent, with comparable systematic errors on the Alcock-Paczynski parameters and the growth of structure, and robust to different HOD prescriptions - thus validating the robustness of the models and the pipelines used for the baryon acoustic oscillation (BAO) and full shape clustering analysis. Our study is relevant for the final eBOSS DR16 'consensus cosmology', as the systematic error budget is informed by testing the results of analyses against these high-resolution mocks. In addition, it is also useful for future large-volume surveys, since similar mock-making techniques and systematic corrections can be readily extended to model for instance the DESI galaxy sample.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.259-265
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• 1995

Antireflection coatings on optical lenses commertially available in domestic market are optically analyzed. Transmission spectra and reflection spectra are collected using spectrophotometers. The apparent absorption spectra around the absorption band edge are dominated by the substrate absorption. The reflection spectra and the apparent absorption spectra at visible region between 400nm and 700nm show very strong correlation to each other except a couple samples. The discrepency observed in the latters are due to an increased absorption in visible region by the substrate, which is negative effect of these samples. An antireflection coating consisted of $SiO_2/TiO_2/SiO_2/ZrO_2/Cr$ is made on c-Si substrate for spectroscopic ellispometry analysis. A film-by-film coating is accomplished and between each film deposition, ex-situ spectroscopic ellipsometry measurements are made. The analysis of the spectroscopic ellipsometry data reveals that the average film densities of $ZrO_2$ and $TiO_2$ reach only 80% of their respective packing densities and thick films are inhomogeneous along film growth direction. Discussions are made toward in-situ, real-time monitoring of the film growth so that a real-time feedback is possible to achieve a post-correction to minor deviations occured in the previous step. step.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.70.5-71
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• 2015

We present a preliminary result from a high-resolution and high signal-to-noise spectroscopic survey, providing atmospheric parameters for about 170 nearby field dwarfs in the Hipparcos catalog. Our preliminary analysis shows that when Hipparcos parallaxes are adopted, a few stars in our sample are too faint compared to main-sequence fitting distances based on our accurately measured [Fe/H]. We discuss magnitude deficits of these field stars in connection with the short Hipparcos distance to the Pleiades.

• Bulletin of the Korean Space Science Society
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• 1992.10a
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• pp.18-18
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• 1992

Spectroscopic CCD observations were carried out for V 1119 Cygni and the spectrum inthe visual region is analysed relative to the SLln with a line-blanketed convective modelatmosphere. Adopted atmospheric parameters are : an effective temperature ( Teff) =7000 K, a surface gravity log g = 3.4. Although our result is dependent onmicroturbulent velocity and damping constant, it was found that Mg in V1719 Cygni isnearly solar, or underabundant by 0.2 to 0.3 dex according to the analysis of5172.684A Mg I line which is relatively free from blending. This is inconsistentwith the previous photometric result wh(:re V1719 Cygni was known as anabnormally metal rich variable.

• Journal of Astronomy and Space Sciences
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• v.12 no.1
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• pp.1-13
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• 1995

We carried out photometric and spectroscopic observatious of the blue compact dwarf galaxy Haro 6 in the Virgo Cluster of Galaxies. The long-slit spectroscopy was employed at three position angles, $\Phi$=$0^{\circ}$, $\Phi$=$30^{\circ}$, and $\Phi$=$120^{\circ}$with CCD camera mounted on the Cassegrain Spectrograph. Based on the mean intrinsic axial ratio < $q_0$ >=0.3, we derived inclination I of the system as $44^{\circ}$using our composite V-band CCD image. Careful analysis on the velocity field of the system shows an asymptotically fiat rotation curve with the maximum rotational velocity $V(r)_{max}$ reaches about 12km/sec. The calculation of the dynamical mass of Haro 6 with a simple mass model is briefly discussed with emphasis on the mass to luminosity ratio. From the IRAS Point Source Cataloque, we derived dust-to-gas ratio which indicates relatively low dust content, thus tempting us to conjecture the youth of the system.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.38.1-38.1
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• 2017

Symbiotic stars are long-orbital-period interacting binaries characterized by extended emission over the whole electromagnetic range and by complex photometric and spectroscopic variability. In this contribution, I will present some high-cadence, long-term optical light curves of confirmed and candidate symbiotic stars in the Magellanic Clouds. By careful visual inspection and combined time series analysis techniques, we investigate for the first time in a systematic way the photometric properties of these astrophysical objects, trying in particular to distinguish the evolutionary status of the cool component, to provide its first-order pulsation ephemeris and to link all this information with the physical parameters of the binary system as a whole. Finally, I will discuss a new, promising photometric technique, potentially able to discover Symbiotic Stars in the Local Group of Galaxies without the recourse to costly spectroscopic follow-up.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.49.2-49.2
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• 2010

We have presented the evolutionary status of four detached double line spectroscopic eclipsing binaries which are CD Tau, CM Lac, HS Hya and ZZ Boo because the component stars of these binary systems still act as a single star. We determined the absolute dimensions of these binary systems using photometric and spectroscopic solutions from analysis of light curves and radial velocity curves. Using the luminosities, effective temperatures and masses we choose evolutionary tracks of these binary systems. Finally we obtained ages and metallicity of the stars. We found that CM Lac and HS Hya are very young stars and their ages are in range of 0.15-1.05 and 0.22-1.14 Gyrs. For CD Tau and ZZ Boo, they are older than the others and their age in range of 1.95-2.95 and 1.48-1.73 Gyrs.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.5
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• pp.437-443
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• 2013

Clathrate samples, using hydroquinone as a host and ethylene or propylene as a possible guest, were prepared and analyzed by means of spectroscopic measurements. Obtained results showed that ethylene can form clathrate compounds with hydroquinone at 4.0MPa and room temperature, while propylene cannot form clathrate compounds. Different formation behaviors of these two olefin compounds can be applied to a clathrate-based storage/recovery of ethylene in a selective way, and can provide useful information on the cavity size of the formed clathrate compounds.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.397-400
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• 2003

In this study, humic and fulvic acids in soils at the vicinity of domestic atomic power plants(NPPs), located in Yungkwang(YK), Uljin(UJ), Kori(KR), Koseong(KS), Wolseong(WS) area, and in volcanic ash soils of the Cheju island(Mt. Hanla(HL), Manjanggul(MJ)) were isolated, and characterized using chemical(elemental analysis, proton exchange capacity, molecular size distribution) and spectroscopic(UV/Vis., IR, FL, $^{13}$ C NMR spectra) methods. The results were compared with one another and compiled for their DB establishments. The humic substances distribution (humic acid, fulvic acid, Humin) in the soils were also determined by IHSS standard method. Main purpose of this study was to provide a basic data needed to evaluate the effect of humic substances on the migrational behaviour of radioactive elements in contaminated surface soil.

• Archives of Pharmacal Research
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• v.28 no.3
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• pp.294-296
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• 2005

Repeated chromatography of the n-hexane-soluble fraction of the MeOH extract of the rhizomes of Zingiber zerumbet led to the isolation of two isomers of 6-methoxy-2E,9E-humula-dien-8-one (1 and 2) and stigmast-4-en-3-one. The structures of 1 and 2 were determined by spectroscopic methods including 10 and 2D-NMR elucidated by analysis of spectroscopic data as well as by comparison with published values. This is the first report on the isolation of compounds 1 and 2 from the nature. Stigmast-4-en-3-one was first isolated from this plant.