Seumul alphabet

The Seumul alphabet was invented on a whim by Bae Jun on 1st January
1997 to celebrate his age of majority. The name means “twenty” in Korean,
and twenty is the age of majority in South Korea, where babies are a year
old at birth, and each passing of a New Year, rather than the birthday,
adds one year to the person’s age.

He designed it to write Korean and used it to write his diary occasionally,
but after realising that it isn’t ideal for writing Korean, he stopped using it.