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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Publications of The Korean Astronomical Society
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The Korean Astronomical Society
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Volume & Issues
Volume 17, Issue 1 - Dec 2002
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THE FULL DERIVATION OF THE JET EQUATION
PARK SEOK JAE ; LEE TAE HYEONG ;
Publications of The Korean Astronomical Society, volume 17, issue 1, 2002, Pages 1~6
DOI : 10.5303/PKAS.2002.17.1.001
In this review article the famous `jet equation` of the neutron stars and black holes will be fully derived for the pedagogical purposes.
PLASMA VELOCITIES IN THE NONSTATIONARY BLACK HOLE MAGNETOSPHERE
PARK SEOK JAE ;
Publications of The Korean Astronomical Society, volume 17, issue 1, 2002, Pages 7~10
DOI : 10.5303/PKAS.2002.17.1.007
In the earlier papers we analyzed the axisymmetric, nonstationary electrodynamics of the central black hole and a surrounding thin accretion disk in an active galactic nucleus. Based on those papers we analyze the axisymmetric, nonstationary force-free black hole magnetosphere and the motion of the plasma. We concentrate on deriving the relations between the velocity components of the plasma and those of the accreting magnetic field lines. We conclude that the former are given by the sum of the latter and the magnetic field terms.
SPHERICALLY SYMMETRIC ACCRETION WITH VISCOSITY
YOO KYE HWA ;
Publications of The Korean Astronomical Society, volume 17, issue 1, 2002, Pages 11~14
DOI : 10.5303/PKAS.2002.17.1.011
Our examination of the relations of spherically symmetric accretion on a massive point object to viscous drag, neglecting gas pressure and using self-similar transformation, shows the behaviors of the asymptotic solutions? in the regions near to and far from the center. The viscosity reduces the free-fall velocity by the factor
, and causes flattening in the density distribution. Therefore, the viscosity leads to the reduction of the mass accretion rate.
THE RELATIVE SUNSPOT NUMBERS IN 2001
SIM K. J. ; MOON Y.-J. ; LEE C. W ; CHANG B. H. ; KIM Y. H. ; KIM J. H. ;
Publications of The Korean Astronomical Society, volume 17, issue 1, 2002, Pages 15~22
DOI : 10.5303/PKAS.2002.17.1.015
We have analyzed 209 data of daily sunspot observations made during the period of January 3 to December 31 In 2001 and presented the daily relative sunspot numbers. During the year of 2001, our annual average of relative sunspot numbers is found to be 92.2. This number is obtained from the averaged daily number of 8.4 spot groups, in which there are about 57.5 distinct spots observed. According to the appearance of 370 spot groups, our analysis shows that the mean life time of spot groups is about 4 day and 20.4 hours.
METEOR SHOWERS OF 10-TH TO 14-TH CENTURY
AHN SANG-HYEON ; BAE HYUN JIN ; CHO HYE JEON ; JUNG SUNG-WOOK ;
Publications of The Korean Astronomical Society, volume 17, issue 1, 2002, Pages 23~40
DOI : 10.5303/PKAS.2002.17.1.023
The spatial distribution of meteoroids or cometary debris along the orbit of the Earth is investigated by analyzing the meteoric records in the Chronicle of the Koryo dynasty (918-1392) which is called Koryosa. Sporadic meteors in this period show the seasonal variation in number, which is similar to the current meteors. We also found that there are a few spikes showing large accumulation of records around the same dates. We regard these spikes as meteor showers in the Koryo period. We compared the dates of meteor showers with those compiled from the historical records around the world including Korea, Japan, China, Arab, and European countries. We discovered three prominent showers and four weak showers. The prominent ones are the Leonids, the Perseids, and the Aquarids and the Orionids pair. The last pair is the remnants of Halley`s comet. The astronomical records written in the history book of the Koryo dynasty are turned out to be accurate and written in a steady manner. We can also see that those records can be useful to contribute the development of modern astronomy and astrophysics.