The earliest use of Korean swords were found to be bronze imports from China and bronze age production started around the 1st Century. Steel making techniques did not arrive until around 450 AD from China. The "Hwando" was a one handed sword with a single edge. In appearance, it looked similar to the Chinese "Jian", which was double edged. Until around the 3rd century, swords were reserved for royalty and high ranking officials and were not in use by the common soldier. In the later part of the Three Kingdoms period, swords were used by calvary and other mounted commanders. They were not used by the infantry (foot soldiers). It wasn't until the Joseon period 15th to 19th centuries) that swords were greater in number and usage and were carried by infantry.
The Japanese utilized a straight sword "tachi" prior to the Mongol invasion. This changed how the sword was used and made after problems with the blades chipping and breaking. The first reference to a sword outside of a "tachi" was called an "uchigatana" in 1185 and was probably the early version of the katana. By the early 1400's, what we think of as a "katana" was in use and carried in the manner which it is still today (cutting edge up).
Soooo...where does that leave things? Yes, the "Hwando" (a single edge, one handed straight sword) predated the "Katana" (a single edge, one handed curved sword). Not sure the relevancy of the topic or where you are trying to go with it?