Next to Paper I (Jeon 2009a), time-series BV CCD images of the open cluster M38 were taken for 4 nights on December, 2009. The observations have been carried out for total 27 nights. In addition to the 20 variable stars in the Paper I, the discovery of 44 new variable stars has been presented in this paper: 6δ Scuti stars, 2γ Doradus stars, 18 eclipsing binaries and 18 semi-long periodic and/or slow irregular type variable stars. For the V photometry of the δ Scuti and γ Doradus stars, multi-frequency analysis was performed using the Discrete Fourier Transform and linear least-square fitting. The period search for the eclipsing binaries and the semi-long periodic and/or slow irregular type variable stars was performed by phase fitting method. As a result, the periods for 23 variable stars among the 44 ones were defined.

From the short-period variability survey (SPVS) in Bohyunsan Optical Astronomy Observatory, we obtained time-series BV CCD images in the region of an open cluster M38 (NGC 1912) for 23 nights from February 1, 2007 to December 7, 2008. We found 18 δ Scuti stars and 2 γ Doradus stars. Among them, only 3 δ Scuti stars were known ones. From the color-magnitude diagram (CMD) of M38, most of them have been located in the instability strip. The two γ Doradus stars have been located within γ Doradus strip of M38. But, only four δ Scuti stars were located within radius 10' from the center of M38. To confirm of their membership for M38, we need more study, such as, proper motion by spectroscopic observation.

Galactic open clusters NGC 1907 and NGC 1912 are known as a binary cluster candidate by Subramaniam et al.(1995). With the SNUO 0.6m telescope, UBV CCD photometric observations were performed for 62 stars in NGC 1907 within the area of 8′×8′ 8′×8′ and 203 stars in NGC 1912 within the area of 15′×15′ 15′×15′ area. We obtained C-M and C-C diagrams. Their mean reddenings are E(B-V) = 0.50±0.03 0.50±0.03 for NGC 1907 and 0.27±0.03 0.27±0.03 for NGC 1912. The distance moduli are estimated as 10.9±0.15 10.9±0.15 and 10.4±0.10 10.4±0.10 for NGC 1907 and NGC 1912, respectively. The ages for these clusters are 400±50Myr 400±50Myr for NGC 1907 and 150±30Myr 150±30Myr for NGC 1912. The distance difference of the two clusters is 300pc and the age difference is 150Myr. These results imply that the two clusters are not physically connected.