• 천문학회보
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• 제18권
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• pp.25.2-26
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• 1993

• 천문학회보
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• 제9권
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• pp.5.4-6
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• 1984

• 천문학회보
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• 제35권1호
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• pp.59.1-59.1
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• 2010

We present wide-field near-IR imaging polarimetry of 30 Doradus, using the InfraRed Survey Facility(IRSF) 1.4 m telescope at the South African Astronomical Observatory. We obtained polarimetry data in J, H, and Ks bands using the JHKs-simultaneous imaging polarimeter SIRPOL. 30 Doradus is located in the Large Magellanic Cloud(LMC) and it is the most active starburst region known in the Local group of galaxies. 30 Doradus is one of the best field to examine the behavior of the interstellar medium and star-formation mechanism under different conditions. We will investigate the structure of magnetic field in 30 Doradus region.

• Journal of Astronomy and Space Sciences
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• 제29권3호
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• pp.245-251
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• 2012

Since the development of surface magnetic features should reflect the evolution of the solar magnetic field in the deep interior of the Sun, it is crucial to study properties of sunspots and sunspot groups to understand the physical processes working below the solar surface. Here, using the data set of sunspot groups observed at the ButterStar observatory for 3,364 days from 2002 October 16 to 2011 December 31, we investigate temporal change of sunspot groups depending on their Z$\ddot{u}$rich classification type. Our main findings are as follows: (1) There are more sunspot groups in the southern hemisphere in solar cycle 23, while more sunspot groups appear in the northern hemisphere in solar cycle 24. We also note that in the declining phase of solar cycle 23 the decreasing tendency is apparently steeper in the solar northern hemisphere than in the solar southern hemisphere. (2) Some of sunspot group types make a secondary peak in the distribution between the solar maximum and the solar minimum. More importantly, in this particular data set, sunspot groups which have appeared in the solar southern hemisphere make a secondary peak 1 year after a secondary peak occurs in the solar northern hemisphere. (3) The temporal variations of small and large sunspot group numbers are disparate. That is, the number of large sunspot group declines earlier and faster and that the number of small sunspot group begins to rise earlier and faster. (4) The total number of observed sunspot is found to behave more likewise as the small sunspot group does. Hence, according to our findings, behaviors and evolution of small magnetic flux tubes and large magnetic flux tubes seem to be different over solar cycles. Finally, we conclude by briefly pointing out its implication on the space weather forecast.

• 천문학회지
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• 제29권1호
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• pp.9-18
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• 1996

We have analyzed vector magnetograms and $H\beta$ filtergrams of two sunspot groups, one in a growing phase and the other in a decaying phase. In this study, the temporal evolution of their magnetic morphology has been investigated in association with solar activity. The morphological variations of the growing and decaying phase of these sunspots revealed in detail the coalescence of small spots into a large spot and the fragmentation of a large spot into many small spots, respectively. Numerous small flares were detected in the spot group during the decaying phase. This seems to be intimately associated with the shearing motions of many spots with different polarities created by fragmentation of a large sunspot. The magnetic flux and the average shear angle are found to be substantially reduced during the decaying phase, especially in the course of the flarings. This implies that the decaying phase of the sunspot is, to some degree, involved with magnetic field cancellation. The growing spot group has not shown any large activities, but numerous small spots have grown into a typical bipolar sunspot.

• 천문학회보
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• 제25권2호
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• pp.36-36
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• 2000

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2000년도 한국우주과학회보 제9권2호
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• pp.36-36
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• 2000

No Abstract, See Full Text

• 천문학논총
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• 제16권1호
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• pp.11-14
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• 2001

In this paper, we simplify the equations of the Macdonald-Thome black hole magnetosphere. Our major assumption is that the 3-D electric and magnetic flux isosurfaces respectively form families of confocal oblate spheroids and hyperboloids. As a result, the magnetospheric equations are greatly simplified, and may provide a useful framework for instances when rigorous, theoretical approaches are not necessary.

• 천문학회지
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• 제29권spc1호
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• pp.331-332
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• 1996

We present 3 rare subtypes of the FFSs observed with high temporal resolution at 4-frequency (1.42, 2.13, 2.84 and 4.2G GHz). The various FFSs occurred during the main and post-flare phase can demonstrate that coronal nonthermal electron acceleration/injection may go through the whole development process of flares, and deduce that there may exist the re-forming of loop-like structures in the post-flare phase, and the complex multi-type magnetic structures in corona.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2007년도 한국우주과학회보 제16권2호
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• pp.37-37
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• 2007