• 천문학회보
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• 제35권2호
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• pp.27.2-27.2
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• 2010

We report the HST pixel analysis results of the interacting face-on spiral galaxy, NGC 5194 (M51), which is the first step of a new observational research project, PANCluG (Pixel Analysis of Nearby Cluster Galaxies). We derive several quantities describing the pixel color-magnitude diagram (pCMD) of NGC 5194, suitable for future comparisons with the pCMDs of other galaxies. We investigate the spatial distribution of pixel stellar populations, finding that the spiral arm pattern and the tidal interaction with NGC 5195 significantly affect the stellar populations in NGC 5194. We find that the pixels corresponding to the central active galactic nucleus (AGN) of NGC 5194 show a very tight sequence in the bright-end of the pCMD, of which spatial distribution seems to agree with the AGN torus region.

• 천문학회보
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• 제43권1호
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• pp.60.1-60.1
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• 2018

We investigate the $SFR-M_{\star}$ relation of the infrared luminous galaxies selected in either $11{\mu}m$ and $15{\mu}m$ from the $5.6deg^2$ of the AKARI NEP-Wide field. From the constructed multi-wavelength catalog spanning $0.3{\mu}m$ to $24{\mu}m$, we select 3,408 S11 > $50{\mu}Jy$ galaxies and 1,896 L15 > $20{\mu}Jy$ galaxies which corresponds to $L_{IR}{\sim}10^{11}L_{\odot}$ at z ~ 0.5 and 0.7 respectively. Photometric redshifts of the selected galaxies were derived using LePHARE and Coleman Extended templates. ~98% S11 selected galaxies are galaxies with (median redshift) ~ 0.4, and ~96% L15 selected galaxies are galaxies with ~ 0.6. Star formation rates and stellar mass of these galaxies were calculated using MAGPHYS which derives physical parameters with SED fitting. In the SFR-$M_{\star}$ diagram, $11{\mu}m/15{\mu}m$ selected galaxies are located in the main sequence of star-forming galaxies at z ~ 1.

• 한국축산시설환경학회지
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• 제21권3호
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• pp.93-98
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• 2015

The objective of this study was to review application of next-generation sequencing (NGS) to investigate microbiome in the livestock sector. Since the 16S rRNA gene is used as a phylogenetic marker, unculturable members of microbiome in nature or managed environments have been investigated using the NGS technique based on 16S rRNA genes. However, few NGS studies have been conducted to investigate microbiome in the livestock sector. The 16S rRNA gene sequences obtained from NGS are classified to microbial taxa against the 16S rRNA gene reference database such as RDP, Greengenes and Silva databases. The sequences also are clustered into species-level OTUs at 97% sequence similarity. Microbiome similarity among treatment groups is visualized using principal coordinates analysis, while microbiome shared among treatment groups is visualized using a venn diagram. The use of the NGS technique will contribute to elucidating roles of microbiome in the livestock sector.

• 천문학회보
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• 제36권2호
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• pp.145.2-145.2
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• 2011

We present the results of simultaneous observations of SiO v = 1, 2, J = 1-0, $^{29}SiO$ v = 0, J = 1-0, and $H_2O$ $6_{16}-5_{23}$ maser lines toward 152 known $H_2O$-only maser sources (the sources which are previously detected only in the 22 GHz $H_2O$ maser emission) using Yonsei and Tamna 21-m radio telescopes of the Korean VLBI Network from 2009 June to 2011 January. Both SiO and $H_2O$ maser emission were detected from 62 sources giving a detection rate of 40.8 %. SiO-only maser emission was detected from 27 sources, while $H_2O$-only maser was detected from 22 sources. We have identified 19 new detections of SiO maser emission for previous non-detection sources and 51 new detections of SiO maser for previously not observed sources. Characteristics of all observed sources in the IRAS two-color diagram is investigated including their evolutionary sequence and mutual relations between SiO and $H_2O$ maser emission. These observational results will be useful for statistical study of asymptotic giant branch (AGB) stars and future VLBI observation.

• 천문학회보
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• 제36권2호
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• pp.142.1-142.1
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• 2011

UBVI and $H{\alpha}$ CCD photometry of IC 1848, one of active star-forming regions in Cas OB6, is carried out as a part of Sejong Open cluster Survey (SOS) project. An OB association is an ideal laboratory for studying the triggered star formation and star formation history. Our purposes are to provide deep photometric data up to 21 mag in V and physical parameters of IC 1848. We classify 79 early-type stars and 186 pre-main sequence (PMS) stars as being the members of the cluster using photometric criteria. The IR excess emission PMS stars by Koenig et al. (2008) are also included as members of IC 1848. Total number of members is 414. We derive the interstellar reddening (=$0.659{\pm}0.058$ mag), reddening law ($R_V=4.0{\pm}0.1$), distance modulus ($V_0-M_V=12.0{\pm}0.1$ mag) using the early-type members of IC 1848. We also determine the age of the cluster ($3.5{\pm}1.5$ Myr) by placing the theoretical isochrones on the HR diagram.

• 천문학회보
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• 제36권2호
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• pp.70.1-70.1
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• 2011

We have investigated properties of merging galaxies in the nearby universe, using Sloan Digital Sky Survey (SDSS) DR7. We first constructed two galaxy samples according to redshift range: Sample 1 for 0 ${\leq}$ z ${\leq}$ 0.025 and Sample 2 for 0.09 ${\leq}$ z ${\leq}$ 0.1. We then identified 118 and 184 merging galaxies among the galaxies in the Sample 1 and 2, respectively, and classified them into different merging types and stages by visual inspection of galaxy images. In the Sample 1, there are more wet mergers than dry mergers, while most merging galaxies in the Sample 2 are dry mergers. The color-magnitude diagram of the merging galaxies in our samples is comparable to that of normal galaxies. Dry mergers tend to locate in the red sequence, while wet and mixed mergers reside mostly in the blue cloud. Unlike some previous studies, we did not find a clear trend that the merger rate increases at higher redshift. However, it is difficult to make a direct comparison of the merger rate found in different studies, because it depends on the number of observed galaxies and criteria for merger classification. From the ratios of emission lines, we infer that the faction of merging galaxies with AGNs is higher in wet mergers than in other types.

• 천문학논총
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• 제4권1호
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• pp.16-30
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• 1989

We present recent data of absolute measurements of flux emmitted in the visible continua of some galactic Wolf-Rayet stars, carried out by means of a two-channel scanner built up cooperatively by the Observatoire de Lyon and the Laboratoire d'Astronomie Spatiale. Our measurements lead to the determination of stellar angular diameters which enable us to compute log $L_*/L_{\odot}$ and to locate the WR stars in the HR diagram: The WR stars are cooler than the zero age main sequence (ZAMS) and the WN7, WN8 types appear more luminous than other subclasses. The stellar wind terminal velocities, $V_{\infty}$, deduced from the empirical relation of the effective temperatures by Underhil1(1983) and $V_{\infty}$ adopted from the work of Willis(1982) show about 2,000km/s. We derived the rate of mass loss for the program stars from the formula, $\dot{M}={\varepsilon}(T_{eff})\;L/V_{\infty}{\cdot}c$ by using the obtained effective temperatures, luminosities and $V_{\infty}$ in this work. Their values range from $\dot{M}=1.4{\times}10^{-5}$ to $\dot{M}=5.8{\times}10^{-5}\;\dot{M}_{\odot}/yr$.

• 천문학회보
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• 제41권1호
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• pp.53.3-54
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• 2016

We present a preliminary result of the Fornax cluster survey as a part of the KMTNet Intensive Nearby Southern Galaxy Group Survey (KINGS). We discovered about 200 new dwarf galaxy candidates from the survey of the $8^{\circ}{\times}6^{\circ}$ area around the Fornax cluster. They have magnitudes ranging from V=17.5 to 22 mag (Mv = -13.8 to -9.3), and they are almost complete to V = 20 mag. Surface brightness profiles of most of these galaxies are fit well by a Sersic law with n ~ 1.0. Structural parameters of these galaxies follow well the scaling relations of dwarf galaxies in the fundamental plane. The color-magnitude diagram of these galaxies shows that they are mostly located at the faint end of the red sequence, indicating that they are the probable member of the Fornax cluster. We also derive a luminosity function of the Fornax cluster by combining the new galaxies with the known galaxies in the previous catalogs. We will discuss the future of the KINGS-Fornax.

• 한국항해항만학회지
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• 제28권8호
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• pp.721-726
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• 2004

본 연구에서는 장치장 운영규칙의 현실성을 높이기 위해서 트랜스퍼 크레인의 작업운영체계를 분석하고 작업우선순위의 적용을 위한 운영규칙의 적용방법을 설명하였다. 또한 장치장에서 주행로의 특성에 따른 트럭의 대기 및 주행로 점거형태를 분석하여 블록에 진입하여 대기할 수 있는 최대 대기차량수를 도출할 수 있는 산정식을 정리하고 공간의 제약상태를 분석하였다. 또한 공간의 제약사항 극복하기 위해서 공간자원을 정의할 수 있는 다작업원칙을 제시하고 그 원칙을 위한 해법과 순서도를 묘사하였다.

• 천문학회보
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• 제37권2호
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• pp.240.1-240.1
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• 2012

We performed simultaneous observations of SiO v=1, 2, $^{29}SiO$ v=0, J=1-0 and $H_2O$ $6_{16}-5_{23}$ maser lines toward 252 OH/IR stars using the Korean VLBI Network 21m telescopes. The observations were carried out from 2011 November to 2012 July for studying SiO and $H_2O$ maser properties associated with the evolutionary stages of OH/IR stars. Both $H_2O$ and SiO masers were detected from 49 sources, one-side maser of SiO and $H_2O$ was detected from 109 and 11 sources, respectively. Mutual relations between SiO and $H_2O$ maser properties are investigated based on statistical analyses. We also investigate these maser properties in the IRAS two-color diagram related with stellar evolutionary sequence.