You are wrong. 뱨 is pronounced as /pyae/ 뵤 is pronounced as /pyo/ 배 is pronounced as /pae/ 보 is pronounced as /po/ Only after ㅈ,ㅊ, the vowel sound ionize(?). 재,쟤 are pronounced as /jae/ 조,죠 are pronounced as /jo/ 채,챼 are pronounced as /chae/ 초,쵸 are pronounced as /cho/ BTW, '계, 례, 몌, 폐, 혜' are allowed to pronounce as [게, 레, 메, 페, 헤] 핑계 -> 핑게 계시다 -> 게시다 폐품(廢品) -> 페품 Here is the list of vowels ㅏ 아 IPA [a̠] ㅑ 야 IPA [ja̠] ㅓ 어 IPA [ʌ̹] ㅕ 여 IPA [jʌ̹] ㅗ 오 IPA [o̞] ㅛ 요 IPA [jo] ㅜ 우 IPA [u] ㅠ 유 IPA [ju] ㅡ 으 IPA [ɯ] ㅣ 이 IPA [i] ㅐ 애 IPA [ɛ̝] ㅒ 얘 IPA [jɛ̝] ㅔ 에 IPA [e̞] ㅖ 예 IPA [je̞] ㅘ 와 IPA [wa̠] ㅙ 왜 IPA [wɛ̝] ㅚ 외 IPA [ø̞ / we̞] ㅝ 워 IPA [wʌ̹] ㅞ 웨 IPA [we̞] ㅟ 위 IPA [ɥi / y] ㅢ 의 IPA [ɰi]

Actually, 뱨 is more like bae, and 폐 is pae. Koreans often mix them up when writing in English, eg: Pusan ('Busan') , Hankook Tyres ('Hangook' - as a final sound, g sounds like k). It happens in Chinese too; Taipei ('Taibei'). I don't know why.. maybe they're just not very familiar with English sounds.. :)