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

Here is Why You Need An Adapter

The outlet and plug type used in Benin are C and E and in South Korea is F. This is how they look like.

South Korea

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

Type F

Benin

In Benin, outlets of type C and E are in use.

Type C

Type E