• 천문학회보
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• 제40권1호
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• pp.88.4-89
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• 2015

The Double Pulsar (PSR J0737-3039) is the only neutron star-neutron star (NS-NS) binary in which both NSs have been detectable as radio pulsars. The Double Pulsar has been assumed to dominate the Galactic NS-NS binary merger rate $R_g$ among all known systems, solely based on the properties of the first-born, recycled pulsar (PSR J0737-3039A, or A) with an assumption for the beaming correction factor of 6. In this work, we carefully correct observational biases for the second-born, non-recycled pulsar (PSR J0737-0737B, or B) and estimate the contribution from the Double Pulsar on $R_g$ using constraints available from both A and B. Observational constraints from the B pulsar favour a small beaming correction factor for A (~2), which is consistent with a bipolar model. Considering known NS-NS binaries with the best observational constraints, including both A and B, we obtain $R_g=21_{-14}{^+28}$ per Myr at 95 per cent confidence from our reference model. We expect the detection rate of gravitational waves from NS-NS inspirals for the advanced ground-based gravitational-wave detectors is to be $8_{-5}{^+10}$ per yr at 95 per cent confidence. We discuss prospects of gravitational-wave detection based on our results. Implications of PSR J1906+0746, which is likely to be another tight NS-NS binary in the Galactic disc supported by recent observation, are also remarked.

• 한국언론정보학보
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• 제39권
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• pp.355-384
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• 2007

이 연구는 한국 영화의 일본 수출이 급격하게 증가한 지난 2002년부터 2006년까지 한국 영화 개봉작 436편을 대상으로 장르와 한류 스타 출연 여부, 메이저 배급 여부, 국내 관객수 등에 따른 일본 수출 성과를 살펴보고자 했다. 우선 장르 면에서는 멜로 영화의 수출 비중이 가장 높아서, 코믹 영화를 즐겨보고, 멜로 영화에 대한 선호도는 다소 저조한 한국 관객과의 차이를 보여준다. 또한, 한류 스타가 출연한 영화 비중은 전체 개봉작의 14%에 지나지 않았으나, 한류 스타가 출연한 영화의 일본 수출 비중은 비한류 스타 출연작에 비해 월등히 높은 것으로 나타나, 일본 수출에 있어 한류 스타의 중요성을 입증해주고 있다. 뿐만 아니라, 메이저 배급 여부와 국내 개봉 성과 또한 일본 수출과 통계적으로 유의한 결과를 나타냄으로써, 배급사의 브랜드 파워와 개별 영화의 1차 시장 성적이 후속 시장에 영향을 주고 있음을 알 수 있다.

• 천문학회보
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• 제44권1호
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• pp.58.2-58.2
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• 2019

Recent observation of the neutron star merger event, GW170817, through both gravitational wave (GW) and electromagnetic wave (EM) observations opened a new way of exploring the universe, namely, multi-messenger astronomy (MMA). One of the keys to the success of MMA is a rapid identification of EM counterpart through optical/NIR observations. We will present the strategy for prioritization of GW source host galaxy candidates to be observed with narrow-field optical telescopes. Our method relies on recent simulation results regarding plausible properties of GW source host galaxies and the low latency localization map from LIGO/Virgo. We will show the test results for both NS merger and BH merger events using previous events and possible future events and describe observing strategy with our facilities for GW events during the ongoing LIGO/Virgo O3 run.

• 한국콘텐츠학회논문지
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• 제11권9호
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• pp.166-173
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• 2011

아시아는 약10년을 주기로 특정 국가의 문화가 유행을 주도하는 경향을 보여 왔다. 1980년대 홍콩영화의 유행을 '항류(港流)'라 칭했고, 1990년대 일본 TV드라마, 애니메이션, 게임 등의 유행을 '일류(日流)'라 칭했으며, 1990년대 말부터 '한류(韓流)'가 시작되었다. 이러한 '~류(流)'라는 표현은 '~식', '~스타일', '~파' 등의 뜻으로 일본에서 사용되어온 일본식 용어다. 최근 일본에서 유행하고 있는 대만 TV드라마와 특정 스타의 인기를 '대류(臺流)'라 부르다가, 중국 영화, 방송, 관광 등의 인기를 총칭하여 '화류(華流)'라고 부르는 것 또한 마찬가지다. 이렇듯 한류라는 용어는 일본에서 사용되는 '~류'의 일환으로 1999년 한국문화부에서 한국대중음악을 홍보하기 위해 배포한 음반 <韓流-Song from Korea>에서 공식적으로 사용되었다. 최근 한류의 열기가 한풀 꺾이며 화류의 열기가 그 자리를 대체하고 있음을 볼 때, 지금이라도 한류의 어원에 대한 잘못된 정보를 바로잡고, 한국문화를 표현하는 용어의 확립과 그 사용에 대한 연구가 필요한 시점이다.

• 천문학회보
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• 제40권1호
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• pp.79.1-79.1
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• 2015

We describe our ongoing project, Intensive Monitoring Survey of Nearby Galaxies. This survey is designed to study transients such as Supernovae (SNe) in nearby galaxies. Our targets are UV-bright (MUV < -18.4) and nearby (d < 50 Mpc) 50 galaxies selected from a GALEX catalog, whose star formation rates are larger than normal galaxies. High star formation in these galaxies ensures that core-collapse supernova explosions occur more frequently in them than normal galaxies. By monitoring them with a short cadence of a few hours, we expect to discover 5 SNe/yr events. Most importantly, we hope to construct very early light curves in rising phase for some of them, which enables us to understand better the physical properties of progenitor star and the explosion mechanism. To enable such a high cadence observation, we constructed a world wide telescope network covering northern, southern hemisphere distributed over a wide range of longitudes (Korea, US, Australia, Uzbekistan and Spain). Data reduction pipe line, detection and classification algorithms are being developed for an efficient processing of the data. Using the network of telescopes, we expect to reach observe not only SNe but also other transients like GRBs, Asteroid, variable AGNs and gravitaional wave optical counter part.

• 천문학회지
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• 제47권3호
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• pp.87-98
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• 2014

We develop a parallel cosmological hydrodynamic simulation code designed for the study of formation and evolution of cosmological structures. The gravitational force is calculated using the TreePM method and the hydrodynamics is implemented based on the smoothed particle hydrodynamics. The initial displacement and velocity of simulation particles are calculated according to second-order Lagrangian perturbation theory using the power spectra of dark matter and baryonic matter. The initial background temperature is given by Recfast and the temperature uctuations at the initial particle position are assigned according to the adiabatic model. We use a time-limiter scheme over the individual time steps to capture shock-fronts and to ease the time-step tension between the shock and preshock particles. We also include the astrophysical gas processes of radiative heating/cooling, star formation, metal enrichment, and supernova feedback. We test the code in several standard cases such as one-dimensional Riemann problems, Kelvin-Helmholtz, and Sedov blast wave instability. Star formation on the galactic disk is investigated to check whether the Schmidt-Kennicutt relation is properly recovered. We also study global star formation history at different simulation resolutions and compare them with observations.

• 천문학회지
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• 제38권2호
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• pp.257-260
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• 2005

We have mapped the W 3 giant molecular cloud in the $C^o\;^3P_1-^3 P_o$ ([CI]) line with the Mount Fuji Submillimeter-wave Telescope. The [CI] emission is extended over the molecular cloud, having peaks at three star forming clouds; W 3(Main), W 3(OH), and AFGL 333. The [CI] emission is found to be strong in the AFGL 333 cloud. We have also observed the $C^{18}O,\;CCS,\;N_2H^+$, and $H^{13}CO^+$ lines by using the Nobeyama Radio Observatory 45 m telescope. In the AFGL 333 cloud, we find two massive cores, which are highly gravitationally bound and have no sign of active star formation. The high [$C^o$]/[CO] and [CCS]/[$N_2H^+$] abundance ratios suggest that the AFGL 333 cloud is younger than the W 3(Main) and W 3(OH) clouds.

• 천문학회보
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• 제43권1호
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• pp.39.2-39.2
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• 2018

GW170817/GRB170817A establishes a double neutron star merger as the progenitor of a short gamma-ray burst, starting 1.7 s post-coalescence. GRB170817A represents prompt or continuous emission from a newly formed hyper-massive neutron star or black hole. We report on a deep search for broadband extended gravitational-wave emission in spectrograms up to 700 Hz of LIGO O2 data covering this event produced by butterfly filtering comprising a bank of templates of 0.5 s. A detailed discussion is given of signal-to-noise ratios in image analysis of spectrograms and confidence levels of candidate features. This new pipeline is realized by heterogeneous computing with modern graphics processor units (GPUs). (Based on van Putten, M.H.PM., 2017, PTEP, 093F01.)

• Journal of Astronomy and Space Sciences
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• 제8권2호
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• pp.149-158
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• 1991

Sixteen unitary Light curves of AR Lac in B and V are made at Yonsei University Observatory in the period of 1980-1988. Some overview findings of light variations are made. (1) The light variation outside eclipse follow none of the wave migration patterns reported by previous investigators. (2) Complicated shapes outside eclipse are apparently much reduced in the light curves of 1983-1984. This suggests than, in the future, AR Lac has a chance to attain a normal state with no complicated interactions. (3) The depths of the primary and the secondary mid-eclipses are changing year-to-year. (4) The K0 star, the larger component, has brightened by $0.^m$ 14 in V, while the G2 star has shown a fluctuation of about $0.^m$05 in V. (5) The B-V values at primary mid-eclipse have no correlation with the depth variations. (6) Independently of the increase of maximum brightness, the B-V colors in the non-eclipsed phases changed slightly over the years.

• 해양환경안전학회지
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• 제20권3호
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• pp.312-317
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• 2014

In this paper, the wave run-up height and depression depth around air-water interface-piercing circular cylinder have been numerically studied. The Reynolds Averaged Navier-Stokes equations (RANS) and continuity equations are solved with Reynolds Stress model (RSM) and volume of fluid (VOF) method as turbulence model and free surface modeling, respectively. A commercial Computational Fluid Dynamics (CFD) software "Star-CCM+" has been used for the current simulations. Various Froude numbers ranged from 0.2 to 1.6 are used to investigate the change of air-water interface structures around the cylinder and experimental data and theoretical values by Bernoulli are compared. The present results showed a good agreement with other studies. Kelvin waves behind the cylinder were generated and its wave lengths are longer as Froude numbers increase and they have good agreement with theoretical values. And its angles are smaller with the increase of Froude numbers.