You have just discovered a difference between a morpheme and phoneme! :-) Korean ㅂ is a single morpheme (smallest unit of meaning) that can be realized as mult

You have just discovered a difference between a morpheme and phoneme! :-) Korean ㅂ is a single morpheme (smallest unit of meaning) that can be realized as multiple phonemes (smallest unit of linguistically meaningful sound), here /p/ in a word initial or syllable final position or /b/ in other syllable initial positions, but the end of /p/ for the final ㅂ is not clearly indicated (applosive). Korean speakers mix them all the way without realizing that, just like other languages. English distinguishes /b/ and /p/ as different morphemes instead, so it's natural that an English approximation uses different characters for them.