It should make no differance for Korean is you use SUBLANG_NEUTRAL or SUBLANG_DEFAULT as there is only one sublang. SUBLANG_NEUTRAL is a fallback that is used if no translation is available in the user's selected sublang. In can be used for locales that have many sublangs (e.g. French have French (France), French (Belgian), French (Canada), French (Swiss) etc) but the language is the same so it's enough to make one translation. While making the translations statistics I've found that SUBLANG_NEUTRAL and SUBLANG_DEFAULT are often randomly mixed. Maybe I should make a wiki page where people knowing the language could write if it requires separate translations for each sublang or one translation with SUBLANG_NEUTRAL and then update all the files?
Mikolaj Zalewski