There were 121 ascents on Everest done by South Korean climbers, but no ascent was achieved without supplemental oxygen.

Now Kim Chang-Ho, who already has climbed the other 13 8000ers without supplemental oxygen, will attempt to be the first South Korean climber, who ascends Everest without it as well. If he succeeds, he will be the first Korean with all 14 8000ers without bottled gas and he will finish for South Korea as the 20th country so far.

If he succeeds in May he would also be the fastest climber with all 14 8000ers with 7 years and about 10 months. Here you can check the table for comparison.

Korea Times article

Korea Herald article