• 천문학회보
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• 제44권2호
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• pp.55.3-55.3
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• 2019

We present a pipeline to estimate baryonic properties of a galaxy inside a dark matter (DM) halo in DM-only simulations using a machine trained on high-resolution hydrodynamic simulations. As an example, we use the IllustrisTNG hydrodynamic simulation of a (75 h^-1 Mpc)³ volume to train our machine to predict e.g., stellar mass and star formation rate in a galaxy-sized halo based purely on its DM content. An extremely randomized tree (ERT) algorithm is used together with multiple novel improvements we introduce here such as a refined error function in machine training and two-stage learning. Aided by these improvements, our model demonstrates a significantly increased accuracy in predicting baryonic properties compared to prior attempts --- in other words, the machine better mimics IllustrisTNG's galaxy-halo correlation. By applying our machine to the MultiDark-Planck DM-only simulation of a large (1 h^-1 Gpc)³ volume, we then validate the pipeline that rapidly generates a galaxy catalogue from a DM halo catalogue using the correlations the machine found in IllustrisTNG. We also compare our galaxy catalogue with the ones produced by popular semi-analytic models (SAMs). Our so-called machine-assisted semi-simulation model (MSSM) is shown to be largely compatible with SAMs, and may become a promising method to transplant the baryon physics of galaxy-scale hydrodynamic calculations onto a larger-volume DM-only run. We discuss the benefits that machine-based approaches like this entail, as well as suggestions to raise the scientific potential of such approaches.

• Journal of Astronomy and Space Sciences
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• 제21권4호
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• pp.529-552
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• 2004

한국, 일본, 중국의 옛 역사 기록에 나오는 별똥비 및 별똥 소나기 기록 가운데 신뢰할 만한 것을 골라서 목록으로 만들었다. 우리의 새 목록에는, 한국의 기록은 35개, 일본은 29개, 중국은 93개의 별똥비 및 별똥 소나기 기록이 들어 있다. 별똥비 및 별똥 소나기는 10세기와 16세기경에 많이 나타났다. 각 별똥비 기록의 근일점 이후 지난 날짜를 조사해본 결과 10세기경에 주로 페르세우스 별똥비에 의한 기여가 컸고, 16세기의 증가는 사자자리 별똥비에 의한 기여가 컸다. 이 결과로부터 10세기의 별똥비의 폭증이 황소자리 별똥 흐름 때문이라는 종래의 견해에 반론을 제기하였다. 우리는 또한 물병자리 에타 별똥비, 페르세우스자리 별똥비, 오리온자리 별똥비, 사자자리 별똥비 등이 지난 2천년 동안 꾸준히 존재해왔음을 알아냈다. 이 가운데 물병자리 에타 별똥비는 기원전 687년 기록이 가장 오래된 것이며, 페르세우스자리 별똥비 기록의 경우 기원후 36년의 것이 가장 오래된 것임을 알아냈다. 또한 핼리혜성이 어미혜성(mother comet)인 물병자리 에타 별똥비와 오리온자리 별똥비의 궤도가 이동한다는 종래의 주장도 부정되었다. 가장 오래된 사자자리 별똥비 기록은 기원후 902년 기록이 아니라 기원후 288년 중국 기록임일 가능성이 큼을 알아냈다. 또한 우리는 용자리 알파 별똥비에 해당하는 별똥비 기록으로 보이는 일련의 기록들을 찾아냈다. 본 연구에서 제시한 한국, 일본, 중국의 별똥비 및 별똥 소나기 목록은 앞으로 별똥비 연구에 도움을 줄 것이다.

• 천문학회보
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• 제32권1호
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• pp.40.2-40.2
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• 2007

• 천문학논총
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• 제27권4호
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• pp.367-373
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• 2012

The first all-sky mid-/far-infrared survey by IRAS in the 1980s, has been followed by only two more, by AKARI, from 2006, and WISE in 2010. I discuss some features of the WISE survey, and highlight some key results from early extragalactic observations that have been made by the science team during the operation of the telescope, and the post-operation proprietary period during which the public release data products were being generated. The efficient survey strategy and very high-data rate from WISE produced a catalogue of 530 million objects that was released to the public in March 2012. The WISE survey strategy naturally provided the deepest coverage at the ecliptic poles, where matched comparison fields were obtained using Spitzer, and where AKARI also observed deep fields. I describe some of the follow-up work that has been carried out based on the WISE survey, and the prospects for enhancing the WISE data by combining the AKARI survey results are also discussed. While the all-sky AKARI survey is less deep than the WISE catalogue, and is still being worked on by the AKARI science team, it includes a larger number of bands, extends to longer wavelengths, and in particular has very complementary band passes to WISE in the mid-infrared waveband, which will provide enhanced spectral information for relatively bright targets.

• 천문학회보
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• 제38권2호
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• pp.48.2-48.2
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• 2013

To understand the connection between active galactic nuclei (AGNs) and star formation, we investigated the relation between AGN bolometric and far-infrared (FIR) luminosities, using type-2 AGNs. By matching type-2 AGNs at z < 0.3 selected from the SDSS based on the emission-line diagnostics, against the AKARI/FIS All-Sky Survey Catalogue and the COSMOS PEP (PACS Evolutionary Probe) Survey Catalogue, we obtained a sample of 729 type-2 AGNs detected in the AKARI survey ($90{\mu}m$) and 17 ones detected in the PEP survey ($100{\mu}m$). For AGN bolometric luminosities, we adopted an estimate based on the [OIII] and [OI] line luminosities. We confirmed that there is a correlation between the AGN bolometric and FIR luminosities with a large scatter, which is consistent with previous studies. However, we claim that this correlation suffers from various artificial effects, e.g., FIR detection limits, survey volumes, and so on. We will discuss the limitations of studying the connection between AGN and star formation using currently available facilities.

• 천문학논총
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• 제32권1호
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• pp.17-19
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• 2017

The first version of the AKARI far-infrared All-Sky Bright Source Catalogue (BSC ver.1) was released to public in March 2010. It has been widely used for various astrophysical researches. We are continuing efforts to produce the next edition. The new version is expected to be improved in accuracy and reliability, as well as its volume. Many improvements to the next version are in progress. The time-line signal is being re-examined throughout the entire data processing. Correction processes for signal linearity and detector responsivity, and procedure for masking signal anomaly are revised. The source extraction process is further tuned and operating parameters will be optimized. These bring better reliability of the source detection and possibly an increase of source numbers. The position accuracy is expected to be improved. Systematic position error seen around the Galactic plane will also be corrected. We also plan to deliver the Faint Source Catalogue version 1.

• 천문학논총
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• 제32권1호
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• pp.305-307
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• 2017

We have identified 22 quasars in the AKARI far-infrared all-sky Bright Source Catalogue, using a matching radius of < 10", and excluding matches which are close to foreground extended sources or cirrus. We have confirmed a relation between quasar optical luminosity and far-infrared luminosity which was found in an earlier study. In addition, we have found that the 11 sources which are at redshift z > 1 are magnified with respect to the predicted far-infrared luminosity, and consider this may be due to gravitational lensing. If confirmed, this would provide a new way to identify lenses; if not, we may have identified an interesting new population of extreme starbursting quasars.

• 복식
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• 제50권5호
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• pp.91-102
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• 2000

The purposes of this study are to determine dimension of apparel expectations. performances and service quality of home shopping and thereby, to analyze effect of apparel commodities dimension (expectations, performances, disconfirmation and satisfaction) and service dimension (service quality and satisfaction) on repurchase intention. The subject were 351 women in the age of twenty to sixty years old who live in Seoul and the suburban of Seoul. The results of this study can be summarized as follows : 1. It was found that home shopping consumers' expectation and performance with apparel commodities were classified 3 factors. On the other hand, the dimensions of service quality were found to have such 3 factors as convenience reliability, personal factor, and apparel one. 2. More frequent users of home shopping scored more on average than less frequent users in terms of service quality, service satisfaction and intention of repurchase. On the other hand, the cable TV users scored more on average than catalogue users In terms of service quality and intention of repurchase. 3. It was found that consumers' intention of repurchase of home shopping were affected by such variables as discofirmation and satisfaction with apparel commodities, service quality and service satisfaction. While less frequent users were affected by disconfirmation and service quality, more frequent users were affected by such variables as apparel commodities satisfaction, service quality and service satisfaction. Meanwhile, both cable TV and catalogue users were found to be affected by service quality and service satisfaction.

• 한국비블리아학회지
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• 제7권1호
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• pp.103-146
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• 1994

Koryokukshinjodaechangkyochongbyollock is an epoch-making catalogue for historical study of proofing Buddhist scriptures in Korea. This bibliography was appended to the 30 volumes which was corrected in 70 Ham, 66 scriptures, and 79 cases. Comparing the differences between the first carved Tripitaka' s texts in Korea, texts made in the Sung dynasty, and the Kitan's texts, this catalogue discovered the name of scriptures, translators, volume number, the changed am order as well as omission, defaults, mistranslation of the Tripitaka made in the Sung dynasty. From Chon-ham to Young-ham, 480 sets among Kaewon-sokkyorock and 43 sets among Chongwonrock were correctly laid. Songshinyokkyong and the Sung Emperor, T'ai Tsung's statements were excluded. Even though it was possible to get these scriptures only by import from Sung, these imported scriptures had no reason to be proofed because of their new version and the author's direct selection in Sung. Shinchipchangkyon-geumeuisuhamlock has no authentic Sung's and Koryo's text books for correction. kyochongbyollock delivered the scriptures listed on Kudaechangmoklock, which gives an important clue to research transformation from the first to the second carved Tripitaka. Through the systematic study of the transformated facts beteween the first carved Tripitaka and the second one, This study would help rebulid the original Chojodaechan-gkynng which has been not yet perfectly discovered itself.

• BMB Reports
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• 제45권12호
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• pp.686-692
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• 2012

Phenotypic analysis of gene-specific knockout (KO) mice has revolutionized our understanding of in vivo gene functions. As the use of mouse embryonic stem (ES) cells is inevitable for conventional gene targeting, the generation of knockout mice remains a very time-consuming and expensive process. To accelerate the large-scale production and phenotype analyses of KO mice, international efforts have organized global consortia such as the International Knockout Mouse Consortium (IKMC) and International Mouse Phenotype Consortium (IMPC), and they are persistently expanding the KO mouse catalogue that is publicly available for the researches studying specific genes of interests in vivo. However, new technologies, adopting zinc-finger nucleases (ZFNs) or Transcription Activator-Like Effector (TALE) Nucleases (TALENs) to edit the mouse genome, are now emerging as valuable and effective shortcuts alternative for the conventional gene targeting using ES cells. Here, we introduce the recent achievement of IKMC, and evaluate the significance of ZFN/TALEN technology in mouse genetics.