The 'codification', you mean the file encoding I presume? Before I go on, I'd like to mention that files do not belong to any particular encoding, that part is entirely up to the text editor you're using. In the case of Notepad++, the encoding is guessed once you open the file, and it defaults to UTF-8 if it can't identify it.
The issue is most likely on your end though; you must select a compatible encoding when editing the file otherwise you'll break the character associations. Any 8-bit encodings will work without issues (such as windows-1252, "ANSI", etc). You should use the "original" encoding of the file if possible, which is 949 (windows-949). As long as you don't use UTF-8, you'll be fine.