You Do Need power plug adapter while traveling from North Korea to Liberia.

Here is Why You Need An Adapter

The outlet and plug type used in Liberia are A, B, C and F and in North Korea is C. This is how they look like.

North Korea

In North Korea, outlets of type C are in use.

Type C

Liberia

In Liberia, outlets of type A, B, C and F are in use.

Type A

Type B

Type C

Type F