• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.43.4-44
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• 2016

The presence of multiple stellar populations is now well established in most globular clusters (GCs) in the Milky Way. The origin of this phenomenon, however, is yet to be understood. In this respect, the study of NGC 2808, an intriguing GC which hosts subpopulations with extreme helium abundances, would help to resolve this problem. In order to investigate chemical abundance patterns among different subpopulations in this GC, we have performed low-resolution spectroscopy for the red-giant-branch (RGB) stars and measured CN & CH bands, and Ca line strength. We have identified at least three subpopulations from the CN abundance distribution. This GC shows CN-CH anti-correlation following the general trend among "normal" GCs. In addition, we have cross-matched our results with the high-resolution data in literature, and found a tight correlation between CN strength and sodium abundance. However, CN is anticorrelated with oxygen abundance, as expected from the well known N(&Na)-O anticorrelation. In this talk, we will discuss the implication of these results.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.119-122
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• 1996

The case for a massive black hole in the center of the Galaxy is reassessed using improved modeling techniques and observational data. A dark mass of ${\~}{\times} 10^6$ Mo is present within 0.2 pc of the Galactic center. However, the available data can be modeled, without appealing to a massive black hole, using an extended distribution of dark stellar remnants (neutron stars and stellar mass black holes) provided that the stellar initial mass function in the central parsec is deficient in stars less massive than $\~$1 Mo. Such a situation may be a natural consequence of repeated gas build-up followed by starbursts in the central region. A clear distinction between this and the massive central black hole model cannot be made using red giant tracers outside 0.2 pc due to uncertainties in the radial velocity dispersion distribution. The cluster of massive early-type emission-line stars in the central parcsec more effectively probe the mass distribution close to Sgr A $\ast$, but their small number and partial rotational support complicate mass determinations. Proper motion determinations for stars within 0.5' of Sgr A$\ast$ may be the most effective means of unambiguously determining the mass distribution in the immediate vicinity of the Galactic center.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.72.2-72.2
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• 2012

We present the results of HI 21 cm line observations to explore the nature of the high-velocity (HV) HI gas at - 173${\circ}$, which appears as faint, wing-like, Hi emission that extends to velocities beyond those allowed by Galactic rotation in the low-resolution surveys. We designate this feature as Forbidden Velocity Wing (FVW) 172.8+1.5. Our high-resolution Arecibo HI observations show that FVW 172.8+1.5 is composed of knots, filaments, and ring-like structures distributed over an area of a few degrees in extent. These HV HI emission features are well correlated with the HII complex G173+1.5, which is composed of five Sharpless HII regions distributed along a radio continuum loop of size 4.4${\times}$3.4, or -138 pc ${\times}$ 107 pc, at a distance of 1.8 kpc. G173+1.5 is one of the largest star-forming regions in the outer Galaxy. The HV HI gas and the radio continuum loop seem to trace an expanding shell. Its derived HI parameters including large expansion velocity (55 km/s) imply the SNR interpretation. Hot xray emission is detected within the HII complex, which also supports its SNR origin. The FVW172.8+1.5 is most likely the products of a supernova explosion(s) within the HII complex, possibly in a cluster that triggered the formation of these HII regions.

• The Journal of the Acoustical Society of Korea
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• v.24 no.6
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• pp.309-316
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• 2005

This paper Presents the geoacoustic inversion with Parallel Multi-Population Genetic Algorithm (PMPGA). This method is the modified form of simple genetic algorithm (SGA), which is devised for complementing the defects of simple genetic algorithm. The light bulb source and vertical line array (VLA) receiver are used for geoacoustic inversion. The results of this study show the geoacoustic Parameters can be estimated by PMPGA and the proposed algorithm is 1.7 times as fast as serial one on an average.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.4
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• pp.167-174
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• 2003

This paper proposes a network processor especially optimized for content switching. With 2Gbps port capability, it integrates packet processor cluster, content-based classification engine and traffic manager on a single chip. A switch fabric architecture is also designed for scale-up of the network processor's capability over hundreds gigabit bandwidth. Applied in real network systems, the network processor shows wire-speed network address translator (NAT) and content-based switching performance.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.57.4-58
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• 2018

We explore the role of various environments in triggering star formation (SF) and narrow-line active galactic nucleus (AGN) in SDSS spiral galaxies and the SF-AGN connection, using a volume-limited sample with $M_r$ < -19.5 and 0.02 < z < 0.055 selected from the SDSS Release 7. To avoid the dependency of AGN activity on bulge mass, the central velocity dispersion of the sample galaxies is limited to have a narrow range of $130{\leq}{\sigma}{\leq}200km\;s^{-1}$. We note that in gas sufficient galaxies, AGN feeding lags behind starburst, whereas as the gas exhausts, the SF slows down and AGN seems to even prevent the SF, and thus divide the high-${\sigma}$ sample into two subsamples according to their cold gas content at central region traced by fiber star formation rate, $SFR_{fib}$. We find that a high density (cluster) environment causes a significant increase in AGN activity as well as gas depletion in host galaxies. However, the finding is only noticeable in the high-${\sigma}$ and low $SFR_{fib}$ sample. It seems that a galaxy interaction with the nearest neighbor directly affects the SF of the central region. However, it is unclear whether it directly affects AGN activity.

• Korean Institute of Interior Design Journal
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• v.26 no.6
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• pp.180-190
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• 2017

The subway station is not only an effective means to solve urban traffic problems, but also a kind of representative city shelters with a variety of functions such as urban beauty and disaster prevention. At the same time, the subway station as public facilities need activate the urban functions and through the effective design schemes for a variety of the facade of underground entrance to improve users' awareness and reliability for the subway station as a city shelters. This study is conducted to purpose the design direction considering design and disaster preventing characteristics of the underground subway station entrance. In addition, it will provide a basic reference for the subway station in the renovation and construction. The study is composed of literature reviews and field survey. The literature reviews through papers and documents related to the city shelters, the components and characteristics of city shelters, and components and characteristics of facade design of underground entrance at subway station. Before the field survey through the online surveys with evacuation capabilities and screening only the subway station. And field survey is conducted on the site with careful observation and confirmation. Last cluster analysis were applied to the finally selected samples by the SPSS Win18.0

• Journal of agriculture & life science
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• v.45 no.5
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• pp.1-8
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• 2011

In this study, 160 tea tree (Camellia sinensis L.) lines were classified by caffeine content using colorimetric methods. Among them, caffeine-rich lines (HR-78, HR-137, HR-82 and HR-123) and poor lines (HP-85, HP-88, HP-19, and HP-131) were selected. To know the difference in morphological and genetic characters between caffeine-rich and poor lines, we used leaf/shoot growth and RAPD methods. Cluster pattern of morphological characters (leaf width, leaf length, leaf area and shoot length) showed that shoot length was longer in caffein-rich lines than in -poor lines. In genetic analysis, amplified DNA bands having various sizes were detected in RAPD analysis where 30 random primers were used. However, the discriminated primer set that distinguish caffein-rich tree line from -poor lines was not found. These results can be used as the basic data to determine the morphological and genetic differences among caffein-rich and -poor lines.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.66.4-66.4
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• 2019

NGC 6822 is a dwarf irregular galaxy whose metal abundance is lower than of the Large Magellanic Cloud. Hubble V is the brightest HII complex where molecular clouds surround the core cluster of OB stars. Because of its proximity (d = 500 kpc), we can resolve the star-forming regions on parsec scales (1 arcsec = 2.4 pc). Using the high-resolution (R = 45,000) near-infrared spectrograph, IGRINS, we observed molecular hydrogen emission lines from photo-dissociation regions (PDRs) and $Br{\gamma}$ emission line from ionized regions. In this presentation, we compare our data PDR models in order to derive the density distribution of the molecular clouds on parsec scales and to estimate the total mass of the clouds.

• Food Science of Animal Resources
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• v.42 no.4
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• pp.672-688
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• 2022

The objective of this study was to explore the potential of front face fluorescence spectroscopy (FFFS) as rapid, non-destructive and inclusive technique along with multi-variate analysis for predicting meat adulteration. For this purpose (FFFS) was used to discriminate pure minced beef meat and adulterated minced beef meat containing (1%, 2%, 3%, 4%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%) of chicken meat as an adulterant in uncooked beef meat samples. Fixed excitation (290 nm, 322 nm, and 340 nm) and fixed emission (410 nm) wavelengths were used for performing analysis. Fluorescence spectra were acquired from pure and adulterated meat samples to differentiate pure and binary mixtures of meat samples. Principle component analysis, partial least square regression and hierarchical cluster analysis were used as chemometric tools to find out the information from spectral data. These chemometric tools predict adulteration in minced beef meat up to 10% chicken meat but are not good in distinguishing adulteration level from 1% to 5%. The results of this research provide baseline for future work for generating spectral libraries using larger datasets for on-line detection of meat authenticity by using fluorescence spectroscopy.