• 한국문헌정보학회지
• /
• 제30권2호
• /
• pp.167-188
• /
• 1996

도서관리 전산화된 정보시스템에서 어떤 특정 이용자그룹에 대한 특성과 이용 능력에 대한 이해의 부족으로 일과 그 관련 얻은 종사자들이 정보1.)스틸을 개발하고 채택하고 운영함에 있어 최상의 선택을 하는 데 사실상 큰 어려움을 겪어 왔다. 본 연구는 한국 내에서의 이용자, 유학생 이용자, 남학생 여학생, 학부생, 대학원생 둥과 같은 특정 이용자 집단의 특성과 이용 능력에 관한 조사를 목적으로 이루어 겼다. 또한 OPAC 사용법을 배우는 경로에 대한 연구와 비 이용자 연구도 동시에 행해졌다. 설문 조사는 대구 지역과 미 Texas지역에 유학 중인 학생들을 대상으로 실시하였으며, 345개의 이용 가능한 데이터를 수진 분석하였다. 여러 종류의 기술적, 추리적, 다변량적 통계분석 방법들을 SPSS의 도움을 얻어 적용하였다. 본 연구에서는 (1)특정 학생 이용자집단의 OPAC에 대한 지식의 분포에서는 통계적으로 유의한 차이가 있었지만. 학부생집단과 예체능 전공의 학생들의 그룹 비교에서는 예외적으로 유의한 차이가 나타나지 않았다. (2)응답자들이 OPAC시스템을 사용할 때 알고 있는 탐색 방법의 숫자와 컴퓨터 사용 시간의 상관관계는 다른 어떤 변수의 상관 계수보다 높았고 컴퓨터 이용 연한, 이용 빈도, OPAC이용 빈도는 도서관 이용 빈도와 수작업 카드 목록의 이용 빈도보다 비교적 높았다는 사실을 밝혀 냈으며, 아울러 이 변수들의 상관 계수와 그 상관 관계들의 순위까지 명확히 제시하였다. 또한 어떤 새로운 시스템을 개발하거나, 채택하거나 이를 운영할 때 참조할 수 있는 결론과 추천하는 내용, OPAC 시스템의 성격을 연구하고자 할 때의 미래 연구 주제도 제안하였다.

• 한국문헌정보학회지
• /
• 제32권4호
• /
• pp.209-225
• /
• 1998

본 연구는 이용자들이 온라인목록을 주제탐색용으로 사용할 때 어떠한 탐색행태특성을 나타내는지를 조사하고자 하였다. 101명에게 한 건의 주제탐색문제를 제시하고 그들의 탐색수행 과정을 관찰하였다. 주요 연구결과는 다음과 같다. 1) 주제탐색을 위해 사용한 주요 탐색의 접근점은 주제필드$(55.2\%)$와 서명필드$(42.2\%)$로서 그 차이는 크지 않았다. 2)주제탐색에서의 탐색실패율은 $59.3\%$로 나타났다. 3)탐색실패의 원인은 부적절한 탐색어사용$(0.5\%)$과 불리안논리자를 기용하지 않은$(42.5\%)$ 결과로 들어났다. 4) 탐색실패에 대처하는 방안으로 탐색어변경$(42.0\%)$이나 탐색 대상필드 변경$(33.8\%)$ 방법이 가장 많이 시도되었다.

• 천문학회보
• /
• 제44권2호
• /
• pp.74.3-74.3
• /
• 2019

SCUBA-2 North Ecliptic Pole survey, one of the ongoing JCMT large programs, is designed to obtain 850 ㎛ imaging data over ~4 deg² around the NEP based on the AKARI NEP-Wide survey. By August 2019, the program is 50 % complete in terms of observing time, increasing the submillimeter coverage by a factor of 2 with the comparable depth. The rms measured in the deepest center is 0.92 mJy/beam, slightly above the 850 ㎛ confusion limit. With 4 σ detection, the source count is 50 % complete at 9 mJy. The surface density of submillimeter galaxies at this flux limit is 200 deg^-2. Multi-wavelength identification of the 850 ㎛ sources was done through the likelihood analysis based on the far-infrared (250-500 ㎛), mid-infrared (18 ㎛), near-infrared (2-4 ㎛), and optical (i-band) source catalog. We are going to present morphologies and physical properties of 850 ㎛ selected submillimeter galaxies with the help of ancillary multi-wavelength datasets over the NEP area.

• 천문학회보
• /
• 제36권2호
• /
• pp.52.2-52.2
• /
• 2011

We searched and studied galaxy overdensities at 0.6 < z < 4.5 in the areas of two GOODS fields. These overdensities are identified by running top-hat filters on the two dimensional spatial distribution of two galaxy samples - a K-band limited, photometric redshift sample at 0.6 < z < 4.5, and BVz-color selected sample targeting overdensities at z ~ 3.7 and z ~ 4.0. Here photometric redshifts are derived from multi-wavelength data ranging from U-band through 8 micron band of the Spitzer. We find 52 overdensities with significances of 3.5-7 ${\sigma}$. The derived masses found to be a > $10^{13}\;M_{\odot}$ with the comoving number density of a few ${\times}10^{-6}\;Mpc^{-3}$ at z ~ 3. In order to understand the high number density of massive overdensities at high redshift, we carried out an analysis of galaxy overdensities using the mock galaxy catalog based on Millennium simulation selected in the same way as the analysis of the observational data. In the simulation, we find 650 galaxy overdensities with a 3.5 ${\sigma}$ detection threshold over $2^{{\circ}2}$ sky field. The number density of the very massive overdensities (M > $10^{14}\;M_{\odot}$) in simulation shows a similar trend with the observation. We further discuss implications of our results.

• 천문학회보
• /
• 제37권2호
• /
• pp.82.2-82.2
• /
• 2012

We present an investigation of X-ray hot gas halo in 21 early-type galaxies(ETGs) from cross-matched sample of XMM-Newton(2XMM-DR3 catalog) and SDSS DR 7(0.025 < z < 0.085 and Mr <-19.5). It has been controversial whether or not the environment affects X-ray luminosity of ETGs. In this research, we mainly considered how dense the surrounding galaxies of the target galaxy are and how isolated the target galaxy is from the nearest neighboring galaxy. It appears that the second environmental factor has more effects on X-ray luminosity (0.5-2 keV) of hot gas halo than the first one. We found that the closer a galaxy is to the nearest neighboring galaxy, the brighter it is when the galaxy is located within the neighbor galaxy's virial radius. However, when a galaxy is located outside the neighbor's virial radius, the luminosity does not show any trend. In this poster, we report preliminary results from our study.

• 한국도서관정보학회지
• /
• 제44권2호
• /
• pp.197-215
• /
• 2013

본 연구는 우리나라 대학도서관의 차세대 OPAC 기능 채택 현황을 조사 분석한 것으로 새로운 OPAC 시스템을 도입하거나 시스템개편을 계획하고 있는 도서관에 유용하게 쓰일 것이다. 본 연구에서는 선행연구들을 검토하여 차세대 OPAC 기능의 예비항목들을 추출하고 이것을 검증하기 위해 파일럿 테스트를 실시하였다. 본연구에서의 조사대상은 우리나라 191개 대학도서관 전수로 하였으며 데이터의 정확성을 기하기 위해 두 명의 연구원이 중복 조사하였다. 수집된 데이터는 PASW Statistics 18을 사용하여 분석하였다. 가장 많이 채택된 차세대 OPAC 기능은 간단검색창이었고, 그 다음은 결과내검색이었다. 클러스터링, 오픈서치플러그인, 적합성순정렬, 철자오류 수정은 소수의 도서관만이 사용하고 있는 것으로 나타났다.

• 천문학회보
• /
• 제44권1호
• /
• pp.78.1-78.1
• /
• 2019

Using a method to correct redshift space distortion (RSD) for individual galaxies, we mapped the real space distributions of galaxies in the Sloan Digital Sky Survey (SDSS) Data Release 7(DR7). We use an ensemble of mock catalogs to demonstrate the reliability of this extension, showing that it allows for an accurate recovery of the real-space correlation functions and galaxy biases. We also demonstrate that, using an iterative method applied to intermediate scale clustering data, we can obtain an unbiased estimate of the growth rate of structure $f\sigma_8$, which is related to the clustering amplitude of matter, to an accuracy of $\sim 10\%$. Applying this method to the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7), we construct a real-space galaxy catalog spanning the redshift range $0.01 \leq z \leq 0.2$, which contains 584,473 galaxies in the North Galactic Cap (NGC). Using this data we, infer $0.376 \pm 0.038$ at a median redshift z=0.1, which is consistent with the WMAP9 cosmology at $1\sigma$ level. By combining this measurement with the real-space clustering of galaxies and with galaxy-galaxy weak lensing measurements for the same sets of galaxies, we are able to break the degeneracy between $f$, $\sigma_8$ and $b$. From the SDSS DR7 data alone, we obtain the following cosmological constraints at redshift $z=0.1$ for galaxies.

• 천문학회보
• /
• 제43권1호
• /
• pp.60.1-60.1
• /
• 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.

• 천문학회보
• /
• 제37권2호
• /
• pp.81-81
• /
• 2012

Since the ultraviolet (UV) flux of an integrated population is a good tracer of recent star formation activities, UV observations provide an important constraint on star formation history (SFH) in galaxies. We present UV color-magnitude relations (CMRs) of early-type dwarf galaxies in the Virgo cluster, based on Galaxy Evolution Explorer (GALEX) UV data and the Extended Virgo Cluster Catalog (EVCC, Kim, S. in prep.). The EVCC covers an area 5.4 times larger (750 deg2) than the footprint of the classical Virgo cluster catalog by Binggeli and collaborators. We secure 1304 galaxies as members of the Virgo cluster and 526 galaxies of them are new objects not contained in the VCC. Morphological classification of galaxies in the EVCC is based on the optical image ("Primary Classification") and spectral feature ("Secondary Classification") of the SDSS data. We find that dwarf lenticular galaxies (dS0s) show a surprisingly distinct and tight locus separated from that of ordinary dwarf elliptical galaxies (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. 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. 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 with models with relatively long delayed star formation. Our results suggest that dS0s are most likely transitional objects at the stage of subsequent transformation of late-type progenitors to ordinary red dEs in the cluster environment. In any case, UV photometry provides a powerful tool to disentangle the diverse subpopulations of early-type dwarf galaxies and uncover their evolutionary histories.

• 천문학회보
• /
• 제39권1호
• /
• pp.41.1-41.1
• /
• 2014

Although the link between activity in the nuclei of galaxy and galactic mergers has been under scrutiny for several years, it is still unclear to what extent and for which populations of active galaxies merger-triggered activity is relevant. The environment of AGN allows an indirect probe of the past merger history and future merger probability of these systems, suffering less from sensitivity issues while extending to higher redshifts, compared to traditional morphological studies of AGN host galaxies. Here we present results from our investigation of the environment of radio selected sources out to redshift z=2. We employ the first data release J-band catalog from the new near-IR Infrared Medium-Deep Survey (IMS) and 1.4 GHz radio data from the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey and a deep dedicated VLA survey of the VIMOS field, covering a combined total of ~20 sq. degrees. Given the flux limit of the combined radio catalog (0.1 mJy), we probe a radio luminosity range of 10^36-10^44 erg/s. Using the second and fifth closest neighbor density parameters, we test whether active galaxies inhabit denser environments and study these overdensities in terms of both distance to the AGN and its luminosity. We find evidence for a sub-population of radio-selected AGN that resides in significantly overdense environments at small scales, although we do not find significant overdensities for the bulk of our sample. We do not recover any dependence between the AGN radio-luminosity and overdensities. We show that radio-AGN inhabiting the most underdense environments in the field have vigorous ongoing star formation. We interpret these results in terms of the triggering and fuelling mechanism of radio-AGN.