It's an interesting one as Korean Air does not have premium economy - I'm assuming here that the ATL-ICN legs are Delta operated.
Looking at expertflyer for premium economy fares JFK-ICN for DL and KE, I see that DL G fares seem to map to KE W fares:
A KE W fare earning 125% Redeemable miles, 150% MQM and 25% MQD by distance according to Delta's partner earning chart