In this paper, we have re-examined the relative sunspot numbers from June 1987 to December 2002 observed at Korea Astronomy Observatory. For this we determined conversion factors (K) for each year data to derive the relative sunspot numbers. The estimated conversion factor ranges from 0.57 to 1.09 and has a trend to decrease with time, which seem to depend on the several effects such as observational system, observation methods, and experience of an observer. Our analysis shows that the newly-determined relative sunspot numbers are in much better agreements with the international sunspot numbers than the previously-determined ones in which the conversion factors were determined only four times. This result implies that we should determine the conversion factor for each year data. From these investigations, we also identified one and half solar cycles form our relative sunspot number.

In an early paper Skumanich suggested the existence of a scaling law relating the mean sunspot magnetic field with the square-root of the photospheric pressure. This was derived from an analysis of a variety of theoretical spot models including those by Yun (1968). These were based on the Schliiter-Temesvary (S- T) similarity assumption. To answer criticisms that such modeling may have unphysical (non-axial maxima) solutions, the S-T model was revisited, Moon et al. (1998), with an improved vector potential function. We consider here the consequences of this work for the scaling relation. We show that by dimensionalizing the lateral force balance equation for the S- T model one finds that a single parameter enters as a characteristic value of the solution. This parameter yields Skumanich's scaling directly. Using an observed universal flux-radius relation for dark solar magnetic features (spots and pores) for comparison, we find good to fair agreement with Yun's characteristic value, however the Moon et al. values deviate significantly.

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.

We have analyzed 210 data of daily sunspot observations made during the period of January 3 to December 31 in 2000 and presented the daily relative sunspot numbers. For this work we estimated the conversion factors to derive the relative sunspot numbers: k=0.72 for the 20 cm refractor and k=0.56 for Solar Flare Telescope in KAO. During the year of 2000, our annual average of relative sunspot numbers is found to be 99.4. This number is obtained from the averaged daily number of 8.9 spot groups, in which there are about 62.5 distinct spots observed. According to the appearance of 423 spot groups, our analysis shows that the mean life time of the spot groups is about 4 day and 12.0 hours.

We have analyzed 221 data of daily sunspot observations made during the period of January 1 to December 30 in 1999 and presented the daily relative sunspot numbers. During the year of 1999, our annual average of relative sunspot numbers is found to be 130.1. This number is obtained from the averaged daily number of 6.7 spot groups, in which there are about 45.9 distinct spots observed. According to the appearance of 384 spot groups, our analysis shows that the mean life time of spot group is about 5 day and 4.6 hours.

We have analyzed 251 data of the daily sunspot observations during the period of January 3 to December 31 in 1998 and present the daily relative sunspot numbers. During the 1998, the prehmmary annual average of the relative sunspot numbers is found to be 84.8 based on 26.6 distinct spots in a single group for 4.6 spot groups. According to the appearance of 286 spot groups, our analysis shows that the mean life time of spot group is about 4 day and 23.6 hours.

We have analyzed the sunspot and aurora data recorded in Go-Ryer-Sa. We have collected 35 records of sunspot observations for 46 days, and 232 records of auroral observations. To objectively estimate the periods of the solar activity appearing in these records a method of calculating the one-dimensional power spectrum from inhomogeneous data is developed, and applied to the sunspot and auroral data. We have found statistically significant 10.5 and 10 year periodicities in the distributions of sunspot and aurora records, respectively. These periods are consistent with the well-known solar activity cycle. There are indications of the long-term variations, but the period is not certain. We have also calculated the cross-correlations between the sunspot and auroral data. In particular, we have divided the aurora data into several subgroups to study their nature. We conclude that the historical records of strong auroral activity correspond to non-recurrent magnetic storms related to the sunspots. On the other hand, the records of weak auroral activity are thought to be related with the recurrent magnetic storms which occur frequently due to the coronal hole near the sunspot minimum.

We have analyzed 255 data of the daily sunspot observations during the period of January 3 to December 31 in 1997 and present the daily relative sunspot numbers. During the 1997, the preliminary annual average of the relative sunspot numbers found to be 28.2 based on 9.7 distinct spots in a single group for 1.4 spot groups. According to the appearance of 366 spot groups, our analysis shows that the mean life time of spot group is about 4 day and 17.0 hours.

We have analyzed 223 data of the daily sunspot observations during the period of January 1 to December 31 in 1996 and present the daily relative sunspot numbers. During the 1996, the preliminary annual average of the relative sunspot numbers found to be 8.8 based on 3.7 distinct spots in a single group for 0.6 spot groups According to the appearance of 123 spot groups, our analysis shows that the mean life time of spot group is about 5 day and 5.8 hours. The proper conversion factor of the Korea Astronomy Observatory(KAO) derived from a comparison of one thousand one hundred and eighty observational sunspot numbers from 1992 to 1996 with those of international sunspot numbers is determined to be 1.17 instead of 0.97 which is in use.

Utilizing a Calcium filter, a large two ribbon flare of an importance 2.5Xj31? was recorded at. King Abdul-Aziz University Solar Observatory (KAAUSO) at the 30th of October 1991. This chromosphenc flare observation, which is of special importance since it is rarely reported, was for a flare that occurred near the south west of the equator at the vicinity of a large sunspot group on an active region known as AR 6891. The observed foot points of this flare had a strange behavior in which the separating motion of the ribbons were not typical of most flares, rather were nearly orthogonal. In this article we present the characteristics of the main sunspot group of this active region and try to investigate its evolution and fragmentation with time. Information regarding magnetic fields and velocity fields are necessary to understand the restructuring of the magnetic field pattern and plasma motion, and hence the changes that could lead to the occurrence of such an interesting flare.

We analyze 280 data of the daily sunspot observations during the period of January 1 to December 31 in 1995 and present the daily relative sunspot numbers. During the 1995, the preliminary annual average of the relative sunspot numbers is found to be 20.1 based on 7.9 distinct spots in a single group for 1.3 spot groups. According to the appearance of 366 spot groups, our analysis shows that the mean life time of spot group is about 5 day and 10.1 hours.

We have examined morphological change and movements of individual sunspots within a sunspot group in association with a large solar flare activity (3B/X1.5) appeared on 13 May 1981. For this purpose we measured distance among spots during the period before and after the flare activity and estimated the average velocity of their movement. Our main results are as follows: (1) The longitudinal displacement among sunspots are generally greater than the latitudinal displacement. (2) During the period the spots moved with an average velocity of 1.2 km/s in longitude and 0.86 km/s in latitude. (3) The most notable change took place in the central part placed between the two ribbons of the flare.

We analyze 271 data of the daily sunspot observations during the period of January 1 to December 31 in 1994 and present the daily relative sunspot numbers. During the 1994, the preliminary annual average of the relative sunspot numbers is found to be 32.9 based on 12.4 distinct spots in a single group for 2.2 spot groups. According to the appearance of 146 spot groups, our analysis shows that the mean life time of spot group is about 4 day and 19.2 hours.

We have analyzed the time series of Ca II H,K and ⋋8498 line profiles taken for a sunspot (SPO 5007) with the Echelle spectrograph attached to Vacuum Tower Telescope at Sacramento Peak Solar Observatory. Each set of spectra was taken simultaneously for 20 minutes at a time interval of 30 seconds. A total of 40 photographic films for each line was scanned by a PDS at Korea Astronomy Observatory. The central peak intensity of Ca II H (Imax), the intensity measured at Δ⋋=-0.1 Å from the line center of ⋋8498 (I⋋8489), the radial velocity (Vr) and the Doppler width (Δ⋋D) estimated from Ca II H have been measured to study the dynamical behaviors of the sunspot chromosphere. Fourier analysis has been carried out for these measured quantities. Our main results are as follows: (1) We have confirmed the 3-minute oscillation being dominant throughout the umbra. The period of oscillations jumps from 180 sec in the umbra to 500 to 1000 sec in the penumbra. (2) The nonlinear character of the umbral oscillation is noted from the observed sawtooth shaped radial velocity fluctuations with amplitudes reaching up to 5~6 km/sec. (3) The spatial distribution of the maximum powers shows that the power of oscillations is stronger in the umbra than in the penumbra. (4) The spatial distributions of the time averaged < Imax > and < Vr > across the spot are found to be nearly axially symmetric, implying that the physical quantities derived from the line profiles of Ca II H and ⋋8498 are inherently associated with the geometry of the magnetic field distribution of the spot. (5) The central peaks of the CaII H emission core lead the upward motions of the umbral atmosphere by 90°, while no phase delay is found in intensities between Imax and I⋋8498, suggesting that the umbral oscillation is of standing waves.

We have analyzed a set of high resolution photographic line profiles of a Zeeman sensitive Fe I λ 6302.5 line taken with the Universal Birefringent Filter over a single round sunspot (SPO 5007) at the Sacramento Peak Solar Observatory. The observed spectra recorded on films are traced by PDS and the traced densities are converted to relative intensity by means of IRAF. The Stokes I and V profiles are then constructed by adding together and subtracting from each other the left and right handed circular polarizations, respectively. The reduced I and V profiles are analyzed by means of the coarse analysis(Auer et al.(1977), Skumanich and Lites(1987)) with the use of inversion technique. It is found that the umbral field strength is about 3000 gauss and the field distribution follows closely the emperical model proposed by Wittmann(1974).