D-4

v-2.3
---
1. method
    => conv_MillSec_to_TimeLabel
    => conv_TimeLabel_to_MillSec

	    ==> done
D-4

v-2.4
---
1. Refresh: DB => "cm7"

	    ==> done
D-4

v-2.5
---
1. MODIFY: column
        => length
           ==> change to a readable one

  	==> done
D-4

v-2.6
---
1. MODIFY column: file_path
            => remove file name

  	==> done
D-4

v-3.0
---
1. save: history

  	==> done
D-4

v-3.1
---
1. when refreshing => refer the history

  	==> done