2) double vowels
1)ㅑ ‘ya’ : single vowel ‘ㅣ’ and single vowel ‘ㅏ’ combined
2)ㅕ ‘yeo’ : single vowel ‘ㅣ’ and single vowel ‘ㅓ’ combined
3) ㅛ ‘yo’: single vowel ‘ㅣ’ and single vowel ‘ㅗ’ combined
4) ㅠ ‘ yu’ : single vowel ‘ㅣ’ and single vowel ‘ㅜ’ combined
5-6) ㅖ/ㅒ’ye’ : single vowel ‘ㅣ’ and single vowel ‘ㅔ/ㅐ’ combined
7) ㅘ ‘wa’ : single vowel ‘ㅗ’ and single vowel ‘ㅏ’ combined
8) ㅝ’wo’ : single vowel ‘ㅜ’ and single vowel ‘ㅓ’ combined
9-10) ㅙ / ㅞ ‘wae’, ‘we’ : single vowel ‘ㅗ’ and single vowel ‘ㅐ’ combined, single vowel ‘ㅜ’ and single vowel ‘ㅔ’ combined
11) ㅚ’oe’ :It was originally a single vowel, but many people recently read this as a double vowel like ‘ㅙ/ㅞ’
12) ㅟ ‘wi’ : single vowel ㅜ’ and single vowel ‘ㅣ’ combined
13) ㅢ’eui’ : single vowel ‘ㅡ’ and single vowel ‘ㅣ’ combined