There are several charts floating around for North Korea, and none of them are sourced.  Many astrologers use the August 10, 1945 date.  At midnight on August 10-11 member of the US War Department made the decision to divide Korea at the 38th parallel.  

Jeff Jawer of Star IQ and Marjorie Orr use a chart for September 10, 1948.  Robert Blaschke uses a chart for midnight on September 9, 1948 and this appears to be the date that is celebrated by the DPRK.  However, it appears that the constitution for the Democratic People’s Republic of North Korea was actually signed on September 5 1948. 

I’m continuing my research and have sent out some inquiries to Jeff, Marjorie and Robert, but if any of you have some good information please post a comment!