You Do Need power plug adapter while traveling from American Samoa to South Korea.

Here is Why You Need An Adapter

The outlet and plug type used in South Korea is F and in American Samoa are A, B, F and I. This is how they look like.

American Samoa

In American Samoa, outlets of type A, B, F and I are in use.

Type A

Type B

Type F

Type I

South Korea

In South Korea, outlets of type F are in use.

Type F