간행물
천문학회지 KCI 등재 SCOPUS Journal of The Korean Astronomical Society
- 발행기관 한국천문학회
- 자료유형 학술지
- 간기 반년간
- ISSN 1225-4614 (Print)2288-890X (Online)
- 수록기간 1968 ~ 2024
- 주제분류 자연과학 > 천문학 자연과학 분류의 다른 간행물
- 십진분류KDC 440DDC 520
권호리스트/논문검색
제45권 제4호 (2012년 8월) 3건
1.
2012.08
구독 인증기관 무료, 개인회원 유료
Astronomical data making such as forming a calendar, period of day, determining the time of rising/setting of the sun and the onset of twilight are essential in our daily lives. Knowing the calendar day of the past is particularly crucial for studying the history of a clan or a nation. To verify previous studies in the calendar day of the Joseon dynasty (1392 – 1910), we investigate the sexagenary cycle of the new moon day (i.e., the first day in a lunar month) by using sources such as results of the calculations using the Datong calendar (a Chinese Calendar of the Ming Dynasty) and the data of Baekjungryeok (a Perpetual Calendar; literally, a one hundred-year almanac). Compared with the study of Ahn et al., we find that as many as 17 sexagenary cycles show discrepancies. In the cases of nine discrepancies, we find that the sexagenary cycles of this study are identical to those of the almanacs at that time. In addition, we study five sexagenary cycles by using the historical accounts of Joseon Wangjo Sillok (Annals of the Joseon Dynasty), Seungjeongwon Ilgi (Daily Reports of Royal Secretariat), Chungung Ilgi (Logs of Crown Prince), and so forth. For the remaining discrepancies, we present historical literature supporting the results of this study. This study will greatly contribute to the identification of the lunisolar calendar days during the Joseon dynasty as the dates of the modern (i.e., Gregorian) calendar.
4,000원
2.
2012.08
구독 인증기관 무료, 개인회원 유료
We present a 1.1mm emission map of the OMC1 region observed with AzTEC, a new large-format array composed of 144 silicon-nitride micromesh bolometers, that was in use at the James Clerk Maxwell Telescope (JCMT). These AzTEC observations reveal dozens of cloud cores and a tail of filaments in a manner that is almost identical to the submillimeter continuum emission of the entire OMC1 region at 450 and 850 μm. We perform Fourier analysis of the image with a modified periodogram and the density power spectrum, which provides the distribution of the length scale of the structures, is determined. The expected value of the periodogram converges to the resulting power spectrum in the mean squared sense. The present analysis reveals that the power spectrum steepens at relatively smaller scales. At larger scales, the spectrum flattens and the power law becomes shallower. The power spectra of the 1.1mm emission show clear deviations from a single power law. We find that at least three components of power law might be fitted to the calculated power spectrum of the 1.1mm emission. The slope of the best fit power law, γ≈−2.7 is similar to those values found in numerical simulations. The effects of beam size and the noise spectrum on the shape and slope of the power spectrum are also included in the present analysis. The slope of the power law changes significantly at higher spatial frequency as the beam size increases.
4,000원
3.
2012.08
구독 인증기관 무료, 개인회원 유료
I present here one approach to general relativistic radiation hydrodynamics. It is based on covariant tensor conservation equations and considers only the frequency-integrated total energy and momentum exchange between matter and the radiation field. It is also a mixed-frame formalism in the sense that, the interaction between radiation and matter is described with quantities in the comoving frame in which the interaction is often symmetric in angle while the radiation energy and momentum equations are expressed in the fixed frame quantities in which the derivatives are simpler. Hence, this approach is intuitive enough to be applied straightforwardly to any spacetime or coordinate. A few examples are provided along with caveats in this formalism.
4,000원
