Your GRF is broken. Other than deleting the files manually in it, there's no way to fix this. The issue comes from the patch file you're sending; you chose the wrong encodings when you made it.
If you use Thor Generator, you have to select ANSI instead of Unicode, since you aren't using Korean file names.
If you use GRF Editor to make the thor patch, the file encodings are handled semi-automatically:
File > New > New Thor > add your files.
Select "root" > Container options > Changing "Patching mode" to "Merge into GRF".
Save and send that instead.