It's very likely that the Kontakt 3 files are encrypted and so conversion software would'nt work on them. Not that you will find any that converts directly to KORG format from kontakt.

To get around the encryption you have to use programs like Extreme Sample Converter as they can run kontakt as a VSTi and digitally sample the notes from the sounds into a new unprotected multisample.

From there you can use a program like Awave Studio to convert the sound to KORG format.

Regards
James