• 천문학회보
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• 제46권1호
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• pp.57.3-58
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• 2021

We performed three-dimensional Monte Carlo dust scattering radiative transfer simulations for FUV light to obtain dust scattered FUV images and compared them with the observed FUV image obtained by FIMS/SPEAR and GALEX. From this, we find the scattering properties of interstellar dust in our Galaxy and suggest the intensity of extragalactic background light (EBL) at FUV wavelength. The best-fit values of the scattering properties of interstellar dust are albedo = 0.38^-0.04_+0.04, g-factor = 0.55^-0.15_+0.10, and EBL = 138^-23₊₂₁ CU for the allsky which are consistent well with the Milky Way dust model of Draine and direct measurements of Gardner et al., respectively. At the high Galactic latitude of |b|>10°, the observation is well fitted with the model of lower albedo = 0.35^-0.04_+0.06 and g-factor = 0.50^-0.20_+0.15. On the contrary, the scattering properties of interstellar dust show higher albedo = 0.43^-0.02_+0.02 and g-factor = 0.65^-0.15_+0.05 near the Galactic plane of |b|<10°. In the present simulation, recent three-dimensional distribution maps of interstellar dust in our Galaxy, stellar distances in the catalog of GAIA DR2, and FUV fluxes and/or spectral types in the TD-1 and Hipparcos star catalogs were used.

• 정보관리학회지
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• 제23권3호
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• pp.49-68
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• 2006

도서관 이용자에게 장애가 없는 정보서비스를 제공하기 위해서는 OPAC의 접근성, 사용성 및 검색성을 향상시키고, 도서의 검색, 식별 및 브라우징의 도구로써 ISBN의 활용가치를 높이는 것이 필요하다. 북마크릿은 웹브라우저의 '즐겨찾기에 추가' 또는 '툴바'에 드래그하여 저장할 수 있는 작은 크기의 자바스크립트이다. 그리고 오픈소스인 북마크릿은 웹페이지에서 ISBN을 추출한 다음, 해당 ISBN으로 도서관의 OPAC에서 도서를 검색할 수 있는 간단하지만 강력한 검색도구이다. 해외의 도서관 시스템 벤더, 도서관, OCLC등은 이용자가 온라인서점의 웹페이지를 살펴보면서 동시에 도서관의 소장 및 대출 정보를 실시간으로 검색할 수 있는 북마크릿을 제공하고 있다. 따라서 본 연구에서는 해외에서 개발되어 활용되고 있는 네 가지 유형의 북마크릿에 대한 적용사례 분석을 통해 북마크릿의 특징과 장 단점을 정리하였다. 이를 통해서 북마크릿의 기본요건과 적용모델을 도출하고, 국내 도서관의 OPAC과 온라인서점에서 북마크릿을 활용한 Library Lookup 서비스 제공방안을 제안하였다.

• 천문학회지
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• 제45권2호
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• pp.31-38
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• 2012

In this study we apply Support Vector Machine (SVM) to the prediction of geo-effective halo coronal mass ejections (CMEs). The SVM, which is one of machine learning algorithms, is used for the purpose of classification and regression analysis. We use halo and partial halo CMEs from January 1996 to April 2010 in the SOHO/LASCO CME Catalog for training and prediction. And we also use their associated X-ray flare classes to identify front-side halo CMEs (stronger than B1 class), and the Dst index to determine geo-effective halo CMEs (stronger than -50 nT). The combinations of the speed and the angular width of CMEs, and their associated X-ray classes are used for input features of the SVM. We make an attempt to find the best model by using cross-validation which is processed by changing kernel functions of the SVM and their parameters. As a result we obtain statistical parameters for the best model by using the speed of CME and its associated X-ray flare class as input features of the SVM: Accuracy=0.66, PODy=0.76, PODn=0.49, FAR=0.72, Bias=1.06, CSI=0.59, TSS=0.25. The performance of the statistical parameters by applying the SVM is much better than those from the simple classifications based on constant classifiers.

• 천문학회보
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• 제38권2호
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• pp.61.2-61.2
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• 2013

We present a study of optically emitting supernova remnants (SNRs) in M31 based on $H{\alpha}$ and [S II] images in the Local Group Survey. Using these images, we have selected objects that have [S II]:$H{\alpha}$ > 0.4 and morphology for typical SNRs. We find 76 new SNRs. We have also inspected 233 SNR candidates presented in previous studies, confirming that only 80 of them are SNRs. Combining these, we produce a master catalog of 156 SNRs in M31. We classify these SNRs according to two types of criteria: the SNR progenitor types (Type Ia and core-collapse (CC) SNRs) and the morphological types. Type Ia and CC SNRs are 23% and 77%, respectively, of the total sample. Most of CC SNRs are concentrated along the spiral arms, while Type Ia SNRs are rather spread over the entire galaxy including the inner region. CC SNRs are brighter in $H{\alpha}$ and [S II] than Type Ia SNRs. The cumulative size distribution of the SNRs with 15 < D < 50 pc is well fitted by a power law with an index, ${\alpha}=2.53{\pm}04$. It indicates that most SNRs in M31 are in Sedov-Taylor phase. Properties of these SNRs show little variation depending on the galactocentric distance. The $H{\alpha}$ and [S II] surface brightness shows a good correlation with X-ray luminosity for the SNRs that are center-bright.

• 천문학회보
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• 제43권2호
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• pp.32.1-32.1
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• 2018

The galactic warp is almost ubiquitous among disk galaxies and suspected to be an imprint of recent interactions with other galaxies. The detailed evolutionary course, however, is still uncertain due to the lack of observational evidence. To address this issue, we construct a new extensive catalog of 412 conspicuously warped disks at z = 0.01 ~ 0.05, based on SDSS DR7. We classify the warp morphology through a visual inspection from the Zooniverse Project and our new automated scheme for the warp measurement. We find an interesting color difference between S-and U-shaped warps. The U-type warp galaxies exhibits considerable color offset towards blue compared to both the S-type warps and the control sample of un-warped galaxies. The effect is even more pronounced for galaxies (a) with the greater warp amplitude and (b) with lower luminosity. This is the first piece of observational evidence that the S- and U-shaped warps are on different evolutionary phases in terms of not only dynamics but stellar populations as well. We discuss the implications in the context of the warp evolution theory.

• 천문학회보
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• 제38권2호
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• pp.47.2-47.2
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• 2013

We present ultraviolet (UV) color-magnitude relations (CMRs) of early-type dwarf galaxies in the Viro cluster, combining Galaxy Evolution Explorer (GALEX) UV data with SDSS optical data, based on the Extended Virgo Cluster catalog (EVCC). We find that dwarf lenticular galaxies (dS0s) show a surprisingly distinct and tight locus separated from that of ordinary dEs, which is not clearly seen in previous CMRs. The dS0s in UV CMRs follow a steeper sequence than dEs and show bluer UV-optical color at a given magnitude. We explore the observed CMRs with population models of a luminosity-dependent delayed exponential star formation history. The observed CMR of dS0s is well matched by models with relatively long delayed star formation. The dS0s are most likely transitional objects at the stage of subsequent transformation of late-type progenitors to ordinary red dEs in the cluster environment. Most early type dwarf galaxies with blue UV colors (FUV-r < 6 and NUV-r < 4) are identified as those showing spectroscopic hints of recent or ongoing star formation activities. In any case UV photometry provides a powerful teel to disentangle the diverse subpopulations of early-type dwarf galaxies and uncover their evolutionary histories. lenticular galaxies, and irregular high surface brightness (HSB) galaxies, respectively. Dwarf elliptical galaxies and dwarf irregular LSB galaxies occupy the similar structural parameter spaces. We suggest that giant elliptical galaxies and dwarf elliptical galaxies may have different origin.

• 천문학회보
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• 제38권2호
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• pp.41.2-41.2
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• 2013

We present a very wide-field survey of dwarf galaxies in the M106 Group using the Sloan Digital Sky Survey Data Release 8, covering an area of $10^{\circ}{\times}14^{\circ}$ around M106. We select 18 new members of the M106 group, 10 of which are new findings. Surface brightness profiles of most of these galaxies are fitted well by an exponential law. Twelve of these galaxies are early-types, and the rest are late-types. We produce a master catalog of the M106 Group galaxies by combining these new galaxies with 30 known galaxies. The faint-end of the luminosity function of these galaxies is fitted by a power law with an index ${\alpha}=-1.22{\pm}0.02$. This slope is much flatter than the value predicted by the ${\Lambda}CDM$ models, but is similar to the values for other galaxy groups. The spatial distribution of the dwarf galaxies in the M106 group is quite different from that of the bright members of the group, requiring a further study.

• Genomics & Informatics
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• 제19권4호
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• pp.37.1-37.7
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• 2021

Genome-wide association studies (GWASs) facilitated the discovery of countless disease-associated variants. However, GWASs have mostly been conducted in European ancestry samples. Recent studies have reported that these European-based association results may reduce disease prediction accuracy when applied in non-Europeans. Therefore, previously reported variants should be validated in non-European populations to establish reliable scientific evidence for precision medicine. In this study, we validated known associations with type 2 diabetes (T2D) and related metabolic traits in 125,850 samples from a Korean population genotyped by the Korea Biobank Array (KBA). At the end of December 2020, there were 8,823 variants associated with glycemic traits, lipids, liver enzymes, and T2D in the GWAS catalog. Considering the availability of imputed datasets in the KBA genome data, publicly available East Asian T2D summary statistics, and the linkage disequilibrium among the variants (r² < 0.2), 2,900 independent variants were selected for further analysis. Among these, 1,837 variants (63.3%) were statistically significant (p ≤ 0.05). Most of the non-replicated variants (n = 1,063) showed insufficient statistical power and decreased minor allele frequencies compared with the replicated variants. Moreover, most of known variants showed <10% genetic heritability. These results could provide valuable scientific evidence for future study designs, the current power of GWASs, and future applications in precision medicine in the Korean population.

• 한국도서관정보학회지
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• 제33권3호
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• pp.235-256
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• 2002

이 연구는 한국도서관협회 목록분과위원회에서 주관하여 마련한 韓國目錄規則 4版(草案)에 대한 문제점을 도출하고 그 개선책을 제시한 일종의 제안이다. KCR4(草案) 전체를 대상으로 하지 않고 규칙 전체에 공통적으로 영향을 미치는 주요 부분인 '제1부 기술' 가운데 '제0장 총칙', '제1장 기술총칙', '제2장 단행본'과 마지막 章인 '제2부 접근점(제21장 접근점에 관한 규칙)'만을 검토대상으로 하여 살펴 본 결과, 용어상의 문제점, 카드목록규칙에만 적용되는 내용, 문맥상 잘못된 부분, 내용이 서로 상반된 부분, 내용에 일관성이 없는 부분, 그리고 규칙조문으로는 부적절한 부분 등 많은 곳에서 문제점이 발견되어 일일이 개선책을 제시하였고 마지막으로 미래에 대비하여 추가로 요망되는 사항을 제언하였다.

• 천문학논총
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• 제7권1호
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• pp.231-253
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• 1992

A model for the distribution of stars in the disk and the spheroid of our Galaxy is reexamined from an edge-on view of the Galaxy obtained by selecting infrared sources from the IRAS Point Source Catalog. The sources are counted as a function of galactic latitude. longitude and $12{\mu}m$ apparent magnitude. The source counts are reasonably separated into the disk component and the spheroid component contributions and each of the contributions is further interpreted as a convolution of a spatial density distribution and a luminosity function based on the least-square fit method. The spatial density of the disk component has an exponential radial scale length of $h_R{\sim}2.6\;kpc$ and the vertical distribution follows a canonical $sech^2$ law with a scale height $h_z{\sim}240\;pc$. The distribution of the spheroid component can be represented by an oblate spheriod with an axis ratio $k{\sim}0.61$ and a de Vaucouleurs' $r^{1/4}$ law with an effective radius of $R_e{\sim}120\;pc$. The steep density gradient of the spheroid component is consistent with that of late M giants in the central bulge. The luminosity functions of the disk and the spheroid component stars resemble respectively those of the K luminosity function of disk M giants (Garwood and Jones 1986) and the bolometric luminosity function of M giants in bulge fields (Frogel et al, 1990).