There seems to be a lot of milestone birthdays in Korean culture.
There's baek il or 100 days.
There's dol, the 1st birthday.
If I recall correctly, there's something when you turn 20 or somewhere around there, where you are officially an "adult."
There's hwan gap or 60.
There's chil soon or 70.
There's pal soon or 80.
So, traditionally, hwan gap or the 60th birthday used to be celebrated elaborately. My grandmother had a huge 60th birthday party in Korea. It's kind of like a "Yay, you made it to old age!" kind of thing... but since people are living longer and longer, I hear that pal soon is the new hwan gap. You heard it here first ladies and gents. My grandmother had another huge 80th birthday party in the USA. Good thing she had it for her 80th... she's now 92 and has major dementia.