In the region of the open cluster M48 (NGC 2548), time-series BV CCD images were taken for 22 nights from February 28 in 2008 to March 17 in 2011. From this observation, we found 10 new variable stars. They include five eclipsing binaries, an RR Lyrae, two δ Scuti, and two semi-periodic and/or slow irregular type variable stars. We fail to find the member stars of the open cluster among the 10 variable stars.
I found evidence that Kim Y ˘ong (金泳, 1749-1817) is the author of the Korean Poch' ˘on'ga with New Charts published in 1792 by the Astronomical Bureau of the Chos ˘on dynasty. I reconstructed a history of Kim Y ˘ong from various literature remained in other persons' anthologies and governmental records. My findings on the author and publication year can help to solve the problem on the origin of star charts in the Poch' ˘on'ga with New Charts. I also considered the changes of Chinese Bu-Tian-Ge and their star charts after Chongzhenglishu (崇禎曆書). I found that the new charts in the book of Huantiantushuo published by Li Mingche (李明徹, 1751-1832) in 1819 are approximately the same to those in the Poch' ˘on'ga with New Charts by Kim Y ˘ong in 1792.
We constructed two test server systems for KMTNet data management. One is the photometry database server which is optimized for stable operation, and the other is the photometric data process server which is optimized for fast I/O between devices. The performances of servers and data storage units were tested using various methods. Database upload was also checked using five different methods. From tests, we concluded that the most efficient method to upload photometric data processing results to database is the use of three nodes with job scheduler under the InnoDB engine. In this study we provide the test results for prototype servers for KMTNet data management.