Source: An introduction to the history of Korean language
(3rd edition), Ki-Moon Lee, 1998.

Old Korean (7th-10th)
i ɨʉ u   1 ? 2 3
 ɜ  ɔ     4   5
 a  ɑ     6   7
VH: 1-?, 2-3, 4-5, 6-7

Early Middle Korean (10th-14th)
i ʉ u    1 2 3
e ə ɔ    4 6 5
  a        7
VH: 2-3, 6-5, 4-7

Later Middle Korean (14th-16th)
i ɨ u    1 6 2
  ə o      4 3
  a ʌ      7 5
VH: 2-3, 6-5, 4-7

Modern Korean (17th-19th)
i ɨ u     1  5/6  2
e ə o    4+1  4   3
ɛ a      7+1  7
VH: 2-3, 4-7

Contemporary Korean (20th)
iy ɨ u    1  2+1 5/6  2
eø ə o   4+1 3+1  4   3
  ɛ a      7+1      7
VH: 2-3, 4-7