anon for this-
This will require some detective work.
On the other hand, I remember that after the deal was done there were several mentions in newspapers and editorials that this deal might be the thing that would result in Carter finally getting a Nobel prize.
Here is an excerpt from a George F. Will opinion piece that appeared in Newsweek on October 28, 2002 which appears to support Korea as a key factor:
A closer examination of the timing of events leads me to the following hypothesis:
The Korean agreement was a decisive factor in tipping the scales to finally give Carter the award. However, by the time the award was actually presented, Korea was clearly violating its agreement to not proceed with the development of nuclear weapons, and had been doing so from day one. Therefore, it would have been an embarrassment to mention it during the ceremony itself. Hence, its omission.