• 제목/요약/키워드: BH

검색결과 646건 처리시간 0.031초

Establishing New Black Hole Mass Estimators of Active Galactic Nuclei with Hydrogen Brackett Lines

  • 김도형;임명신
    • 천문학회보
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    • 제37권1호
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    • pp.51.2-51.2
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    • 2012
  • Red Active Galactic Nuclei (AGNs) are suspected to intermediate stage between ULIRG and AGN phase. As well as, red AGNs are suspected to have more than 50% of whole AGN population. For understanding the characteristics of red AGN, Black Hole (BH) mass is a key property and can not be estimated by existed method such as reverberation mapping and single epoch method using 5100A continuum and Balmer lines. Thus we still don't know their characteristics and properties in clearly. To estimate properties of red AGNs without the effect of dust extinction, we obtained Near InfraRed (NIR) spectra of 31 reverberation mapped AGNs and 49 Palomar-Green(PG) Quasi-Stellar Objects (QSOs) by using the infrared camera (IRC) of AKARI space telescope with unique wavelength range 2.5-5.0 ${\mu}m$. Upon this spectra, we measured the FWHM and luminosity of Brackett ${\alpha}$ and ${\beta}$ lines for deriving new BH mass estimators of AGNs.

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일점전개함수에 의한 Heteronuclear Diatomic Molecules의 Force Constants의 계산 II. Cubic Force Constants (Calculation of the Force Constants of Heteronuclear Diatomic Molecules by Use One Center Function. Ⅱ. Cubic Force Constants)

  • 김호징;김희준
    • 대한화학회지
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    • 제16권5호
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    • pp.261-264
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    • 1972
  • LiH, BeH, BH, CH, NH 및 OH 등의 heteronuclear diatomic molecules의 quadratic force constants를 Bishop등의 일점전개함수에 의하여 계산하였다. 계산의 master formula는 본 저자들 중의 한 사람에 의하여 이미 제안된 바 있다. 계산 결과는 실험치와 잘 일치하였다. 일점전개함수의 전개중심에 가까이 위치하고 있는 원자핵의 주위에서의 전자분포는 실제에서 비교적 벗어나며, $P_2(cos{\theta})/r^3$의 전개 중심을 이 원자핵에 잡으면 제안된 식으로부터 그릇된 결과가 얻어지는 것을 발견하였다

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Diastereoselective Reduction of 2,3-Dioxo-4-carboxy-5-substituted Pyrrolidines Using NaBH4/AcOH and Heterogenous Hydrogenation Reactions

  • Mohammat, Mohd Fazli;Mansor, Nurul Shulehaf;Shaameri, Zurina;Hamzah, Ahmad Sazali
    • 대한화학회지
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    • 제59권1호
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    • pp.31-35
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    • 2015
  • Diastereoselective reduction of 2,3-dioxo-4-carboxy-5-(substituted)pyrrolidine 1 by $NaBH_4/AcOH$ and heterogenous hydrogenation were reported. Stereochemical assignment and diastereomeric ratios of the products were determined using $^1H$ NMR and single crystal X-ray analyses. The steric factors of the C-5 substituents of the pyrrolidinone was shown to have an interesting influence on both the yield and diastereoselectivity of the reduced product.

항진균제 Naftifine 구조와 관련된 알릴아민류의 합성 (Synthesis of Naftifine-Related Allylamine as a Potential Antimycotics)

  • 김욱;박은주;서희경;신부안;최보길;정병호
    • 약학회지
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    • 제37권3호
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    • pp.247-253
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    • 1993
  • Eight new derivatives of allylamine which are related to naftifine and expected to have antifungal activity were synthesized. Schiff base 2a-2d and 2'e-2'h were obtained by conventional methods using trans-cinnamylamine or trans-cinnamaldehyde. The reduction of azomethine linkage with NaBH$_{4}$ yielded secondary amine 3a-3h, which were then methylated by means of HCHO and excess NaBH$_{4}$ or HCOOH to give 4a-4h.

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Estimating Black Hole Mass in Active Galactic Nuclei with Hydrogen Brackett lines

  • 김도형;임명신
    • 천문학회보
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    • 제35권2호
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    • pp.32.2-32.2
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    • 2010
  • Red dusty Active Galactic Nuclei (AGNs) are suspected to mid-stage between ULIRG and AGN phase. As well as, they are suspected that they have more than 50% of AGN population. To understand character of red AGN, Black Hole (BH) mass of red AGN is a key property and haven't measured by existing method such as reverberation mapping and single epoch method. So we still don't know their character and properties clearly. To estimate properties of red AGNs escape from effect of dust-obscuration, we have obtained Near InfraRed (NIR) spectra of 31 reverberation mapped AGNs and 49 Palomar-Green(PG) Quasi-Stellar Object (QSO) using the infrared camera (IRC) for AKARI with unique wavelength range 2.5-$5.0{\mu}m$. From this spectra, we measured the FWHM and luminosity of brackett ${\alpha}$, ${\beta}$ at 4.0, 2.6 micron meter for deriving new BH mass estimators based on the properties of Brackett line emission.

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bservational Evidence for the Coevolution between Supermassive Black Holes and Host Galaxies

  • Kim, Minjin
    • 천문학회보
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    • 제42권1호
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    • pp.27.4-27.4
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    • 2017
  • (1) The correlation between the mass of supermassive black holes (SMBHs) and the properties of their host galaxies suggests that SMBHs and host galaxies are closely linked in their formation and evolution. While the exact origin of their relationship is still under debate, theoretical models often invoke feedback from active galactic nuclei as a crucial mechanism for establishing the BH-host correlation. In the first part of my talk, I will present possible observational biases in the BH-host relation, and methods to overcome these biases. I will also report our efforts to find observational sign of the AGN feedback in high-z young luminous AGNs. (2) While intermediate-mass black hole (IMBH) is thought be cosmologically important class to understand the link between stellar mass black holes and SMBHs, it is extremely rare in the present-day Universe. In the second part of this talk, I will report a Gemini/GMOS-N IFU study of an ultraluminous X-ray source in NGC 5252, which is a possible candidate of an off-nuclear non-stellar black hole.

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주기정비를 고려한 단일기계 일정계획을 위한 휴리스틱 알고리즘 설계 (Heuristic Algorithm for the Single-machine Scheduling with Periodic Maintenance)

  • 이상헌;이인구
    • 대한산업공학회지
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    • 제34권3호
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    • pp.318-327
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    • 2008
  • This paper considers a single-machine scheduling problem with availability constraints. In many realistic situations, machines may not be always available due to various reasons such as maintenance, breakdown and repair. However, most literature on scheduling assume that the machines are available at all times. This paper deals with a single-machine scheduling problem with periodic maintenance. If the maintenance decision is made jointly with the job scheduling, the system will be more effective. The objective is to minimize the total completion time of jobs. This problem is proved to be NP-hard in the strong sense. The proposed breaking heuristic(BH) algorithm rule is established by some theorems and conditions. Our computational results show that the BH algorithm is much more efficient than existing heuristic.

Preliminary Identification of Branching-Heteroscedasticity for Tree-Indexed Autoregressive Processes

  • Hwang, S.Y.;Choi, M.S.
    • Communications for Statistical Applications and Methods
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    • 제18권6호
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    • pp.809-816
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    • 2011
  • A tree-indexed autoregressive(AR) process is a time series defined on a tree which is generated by a branching process and/or a deterministic splitting mechanism. This short article is concerned with conditional heteroscedastic structure of the tree-indexed AR models. It has been usual in the literature to analyze conditional mean structure (rather than conditional variance) of tree-indexed AR models. This article pursues to identify quadratic conditional heteroscedasticity inherent in various tree-indexed AR models in a unified way, and thus providing some perspectives to the future works in this area. The identical conditional variance of sisters sharing the same mother will be referred to as the branching heteroscedasticity(BH, for short). A quasilikelihood but preliminary estimation of the quadratic BH is discussed and relevant limit distributions are derived.

Nanoconfinement effects of MCM-41 on the thermal decomposition of metal borohydrides

  • Kim, Sanghoon;Song, Hyejin;Kim, Chul
    • 분석과학
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    • 제31권1호
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    • pp.1-6
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    • 2018
  • We used differential scanning calorimetry and a thermogravimetric analysis to investigate the effect of being confined in mesoporous MCM-41 on the decomposition of lithium borohydride and magnesium borohydride when heated. The confinement did not cause a phase transition of the metal borohydrides inside MCM-41, but did lower their decomposition temperature. With the exception of a lowering of the temperature, the decomposition reaction mechanism of the metal borohydrides was nearly the same for both the bulk and confined samples.