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검색결과 190건 처리시간 0.033초

Are Quasars Growing Fast in the Early Universe?: The Lowest Eddington Ratio Quasar at z~6

  • Kim, Yongjung;Im, Myungshin;Jeon, Yiseul;Kim, Minjin;Hyun, Minhee;Kim, Dohyeong;Kim, Jae-Woo;Taak, Yoon Chan;Yoon, Yongmin;Choi, Changsu;Hong, Jueun;Jun, Hyunsung David;Karouzos, Marios;Kim, Duho;Kim, Ji Hoon;Lee, Seong-Kook;Pak, Soojong;Park, Won-Kee
    • 천문학회보
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    • 제42권2호
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    • pp.44.3-45
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    • 2017
  • To date, luminous quasars at z ~ 6 have been found to be in maximal accretion with the Eddington ratios, ${\lambda}Edd$ ~ 1, suggesting enhanced nuclear activities in the early universe. However, this may not be the whole picture of supermassive black hole (SMBH) growth since previous studies have not reached on faint quasars that are more likely to harbor SMBHs with low ${\lambda}Edd$. To understand the accretion activities in quasars at high redshift, we obtained the deep near-infrared (NIR) spectrum of a quasar, IMS J2204+0112, one of the few faintest quasars that have been identified at z ~ 6. From the NIR spectrum, we find that IMS J2204+0112 harbors a SMBH with about a billion solar mass, with ${\log}({\lambda}Edd)=-0.91$. This is the lowest accretion rate found so far for quasars at z ~ 6, but a common value among quasars at z ~ 2. The inclusion of this object in the ${\lambda}Edd$ analysis gives the intrinsic ${\lambda}Edd$ distribution of z ~ 6 quasars, which is lower than previous results that are based on bright quasars, but it is still higher than ${\lambda}Edd$ of z ~ 2 quasars. Although the number statistics needs to be improved in future, the low peak ${\lambda}Edd$ value is consistent with the SMBH growth from a massive black hole seed (~ 105 Msun) or from a stellar mass black hole through short-duration super-Eddington accretion events (${\lambda}Edd$ > 10).

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OpenGL을 이용한 모델 기반 3차원 다시점 객체 구현 (Model-Based Three-dimensional Multiview Object Implementation by OpenGL)

  • 오원식;김동욱;김화성;유지상
    • 방송공학회논문지
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    • 제13권3호
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    • pp.299-309
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    • 2008
  • 본 논문에서는 OpenGL을 이용한 모델기반 3차원 다시점 영상의 객체 구현을 위한 구성과 각 모듈에 적용되는 기법을 제안한다. 한 장의 텍스쳐 이미지와 깊이 정보 영상을 가지고 다시점 객체를 생성하기 위해, 먼저 깊이 정보의 전처리 과정을 거친다. 전처리된 깊이 정보는 OpenGL 상에서의 일정 간격의 꼭지점 정보로 샘플링 되며, 깊이 정보를 z값으로 가지는 3차원 공간 좌표상의 점이다. 이 꼭지점 정보를 기반으로 텍스쳐 맵핑을 위한 다각형을 구성하기 위해 딜루이니 삼각화(Delaunay triangulations) 기법을 적용한다. 이렇게 구성된 다각형 위에 텍스쳐 이미지를 맵핑하여 OpenGL의 좌표 연산을 통해 시점을 자유롭게 조정할 수 있는 동영상 출력 가능한 객체를 만들게 된다.

3D Laser Scanning을 이용한 댐체의 안정성 검토 (A Examination on Stability of Dam using 3D Laser Scanning System)

  • 이재원;손호웅;윤부열
    • 한국측량학회:학술대회논문집
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    • 한국측량학회 2007년도 춘계학술발표회 논문집
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    • pp.451-454
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    • 2007
  • There is an inseparable relation between human race and engineering work. As world developed into highly industrialized society, a diversity of large structures is being built up correspondently to limited topographical circumstance. Though large structures are national establishments which provide us with convenience of life, there are some disastrous possibilities which were never predicted such as ground subsidence and degradation. It is very difficult to analyze the volume of total metamorphosis with the relative displacement measurement system which is now used and it is impossible to know whether there is structural metamorphosis within a permissible range of design or not. In this research with an object of 13-year-old earthen dam, through generating point-cloud which has 3D spatial coordinates(x, y, z) of this dam by means of 3D Laser Scanning, we can get real configuration data of slanting surface of this dam with this method of getting a number of 3D spatial coordinates(x, y, z). It gives 3D spatial model to us and we can get various information of this dam such as the distance of slanting surface of dam, dimensions and cubic volume. It can be made full use of as important source material of reinforcement and maintenance works to detect previously the bulging of the dam through this research.

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THE INCOMPLETE GENERALIZED τ-HYPERGEOMETRIC AND SECOND τ-APPELL FUNCTIONS

  • Parmar, Rakesh Kumar;Saxena, Ram Kishore
    • 대한수학회지
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    • 제53권2호
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    • pp.363-379
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    • 2016
  • Motivated mainly by certain interesting recent extensions of the generalized hypergeometric function [Integral Transforms Spec. Funct. 23 (2012), 659-683] and the second Appell function [Appl. Math. Comput. 219 (2013), 8332-8337] by means of the incomplete Pochhammer symbols $({\lambda};{\kappa})_{\nu}$ and $[{\lambda};{\kappa}]_{\nu}$, we introduce here the family of the incomplete generalized ${\tau}$-hypergeometric functions $2{\gamma}_1^{\tau}(z)$ and $2{\Gamma}_1^{\tau}(z)$. The main object of this paper is to study these extensions and investigate their several properties including, for example, their integral representations, derivative formulas, Euler-Beta transform and associated with certain fractional calculus operators. Further, we introduce and investigate the family of incomplete second ${\tau}$-Appell hypergeometric functions ${\Gamma}_2^{{\tau}_1,{\tau}_2}$ and ${\gamma}_2^{{\tau}_1,{\tau}_2}$ of two variables. Relevant connections of certain special cases of the main results presented here with some known identities are also pointed out.

후기 라깡이론에서 실재에 관한 연구 (Study of the Real in the Post-Lacanian Theory)

  • 박수진
    • 조형예술학연구
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    • 제6권
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    • pp.60-80
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    • 2004
  • This study aims at the observation of the Real in the Post-Lacanian theory. It is focused on two questions as ideology and fantasy. On this basis Slavoj $\v{Z}i\v{z}ek$ has rearticulated the theory of ideology by reexamining Althusser's version of it critically. The ideology is the logic of fantasy based on the foreclosure. And the ethical act of identifying with the symptom is absolutely called for in order to radically rearticulate it. The really key element in the concept is now found to be Lacanian object a, the symptom as jouissance. In additional, the two part of the study, far from belonging to two different domains, that of political analysis and artistic analysis, relate to each other like the two surfaces of a Moebius band. Finally, the role of the Lacanian real is radically ambiguous: true, it erupts in, the form of a traumatic return, derailing the balance of the Order, but it serves at the same time as a support of this very balance. The real functions here not as something that resists symbolization, as a meaningless leftover that can not be integrated into the symbolic universe, but on the contrary, as its last support.

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서부태평야지역에서 일본 다랑어선망어업의 어획특성 (Catch Specification of Japanese Tuna Purse Seine in the Western Pacific Ocean)

  • 김형석
    • 수산해양기술연구
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    • 제35권3호
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    • pp.243-249
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    • 1999
  • Specificity of catches has been analyzed to japanese tuna purse seine A principle component analysis was used to improve the efficiency of fishing and increase sustainable production and productivity of Korean tuna purse seine.The result are as follows;From the principal component analysis of the fish catches, the first principal component(Z1) to promote principal component score was skipjack Kastsuwonus Pelamis, LINNAEUS and yellowfin tuna Thunnus Albacares, BONNATERRE (Small : smaller than 10kg) and proportion was 86.8% of total. The second principal component(Z2) to increase principal component score was yellowfin tuna (Large : larger than 10kg) and proportion was 9.5%.On the other hand, fish operating that have caught skipjack and yellowfin tuna (Small and Larger) was not so much. Fish catches for one species raised volume of the catches while catches for multi-species decreased it since principal composition score for one species and both species together has been increased.Fish school could be divided into three groups of schools each of which was associated with drift objects, payaho and ship, school associated with shark, whale and porpoise and school of breezing, feeding and jumping from proportion of principal component analysis for fish catches of school types. However, the biological pattern is different among school associated with ship, payaho and school associated with drift objects for analysis eigen vector. School associated with ship, payaho and school associated with drifting object associated is judged as school which be assembled to vessel and drifted log temporary.

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Bi-material Bolus for Minimizing the Non-uniformity of Proton Dose Distribution

  • Takada, Yoshihisa;Kohno, Syunsuke
    • 한국의학물리학회:학술대회논문집
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    • 한국의학물리학회 2002년도 Proceedings
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    • pp.214-215
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    • 2002
  • Generally uniform dose distribution is assumed to be formed in a target region when a conventional dose formation method using a broad proton beam, a fixed modulation technique, a bolus and an aperture is employed. However, actual situations differ. We usually find non-uniformity in the target region. This is due to the insertion of a range-compensating bolus before the patient. Since the range-compensating bolus has an irregular shape, the scattering in the bolus depends on the lateral position. Dose distribution is overlapping results of dose distribution of pencil-proton beams traversing different lateral positions of the bolus. The lateral extent of dose distribution of each pencil beam traversing the different position differs each other at the same depth in the target object. This is a cause of the non-uniformity of the dose distribution. Therefore the same lateral extent of dose distribution should be attained for different pencil beams at the same depth to obtain a uniform dose distribution. For that purpose, we propose here a bi-material bolus. The bi-material bolus consists of a low-Z material determining mainly the range loss and a high-Z material defining mainly the scattering in the bolus. After passing through the bi-material bolus, protons traversing different lateral positions will have different residual range yet with the same lateral spread at a certain depth. Using the optimized bi-material bolus, we can obtain a more uniform dose distribution in the target region as expected.

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The Color Variability Monitoring of HBC722

  • 백기선;박수종;;강원석;전이슬;최창수;이정은;임명신
    • 천문학회보
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    • 제37권2호
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    • pp.103.1-103.1
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    • 2012
  • We present the results of SDSS r, i and z band photometry for HBC722 (also known as $LkH{\alpha}$ 188 G4, PTF10qpf and V2493 Cyg), with Camera for Quasars in Early uNiverse (CQUEAN) attached to 2.1m Otto Struve telescope at McDonald Observatory, USA. HBC722 is a newly erupted FU Orionis type object, which produced optical outburst (${\Delta}V$=4.7 mag) over a year that peaked in 2010 September. We carried out the monitoring observations during 48 nights from 2011 April to 2012 June to check the short-term and the long-term variabilities for chasing the Keplerian rotation of the system. Comparing the photometric results of r, i and z band, we describe the color variability which is related to the physical properties of the system like circumstellar disk and accretion process.

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수치사진측량기법에 의한 Fender의 3차원 수치모형 생성 (3D-Digital Model Generation of an Automobile-Fender Using Digital Photogrammetry)

  • 정성혁;황창섭;이재기
    • 한국측량학회지
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    • 제19권2호
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    • pp.147-154
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    • 2001
  • 최근 수치사진측량은 다양한 수치영상처리기법의 연구와 각종 수치영상 취득.처리 장비의 보급에 힘입어 그 실용화에 관한 연구가 활발히 이루어지고 있으며, 건설.산업분야, 의학분야, 고고학분야 등에서 대상물의 위치, 특성 및 크기 결정에 폭넓게 이용되고 있다. 본 연구에서는 수치사진측량 기법을 이용하여 자동차 몸체와 같이 유선형으로 이루어진 대상물의 정밀측정 가능성을 알아보기 위하여 대상물의 3차원 수치모형 생성을 하는 방법으로 연구를 수행하였다. 계산된 좌표값들의 표준편차는 ${\sigma}_x$=0.434mm, ${\sigma}_y$=0.619mm, ${\sigma}_z$=0.387mm 이었으며, 이는 자동차 설계분야에서 요구하는 정확도 내에 충분히 수렴하는 것으로, 수치사진측량 기법이 산업분야에 있어서 충분히 활용될 수 있음을 입증하였다.

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거울영상을 이용한 3차원 좌표해석에 관한 연구 (A Study on Three-dimensional Coordinates Analysis Using Mirror Images)

  • 유복모;이현직;정영동;오창수
    • 한국측량학회지
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    • 제4권1호
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    • pp.25-36
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    • 1986
  • 지상사진으로 3차원 대상물에 대한 모든면의 절대좌표를 구하기 위해서는 최소 세쌍 이상의 모델이 필요하게 된다. 본 연구에서는 거울을 영상매개체로 이용하여 한쌍의 입체모델을 촬영하므로서 대상물의 모든면에 대한 3차원 좌표를 분석할 수 있는 기법을 연구하였으며, 거울면의 왜곡을 보정하기 위한 오차보정함수를 도입하여 거울영상기법의 정확성과 효용성을 증진시키는데 목적이 있다. 거울평면 방정식을 이용하여 거울에 투영된 점을 실제대상물상의 동일점으로 변환한 결과 X좌표의 오차가 가장크게 나타났으며, Y, Z좌표에서는 1mm 정도의 절대좌표오차를 나타내었고, 좌우거울의 보정함수를 도입하여 거울에 의한 왜곡을 보정하므로서 근거리 사진측량의 기대정확도에 만족됨을 알 수 있었다.

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