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

Here is Why You Need An Adapter

The outlet and plug type used in North Korea is C and in Swaziland is M. This is how they look like.

Swaziland

In Swaziland, outlets of type M are in use.

Type M

North Korea

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

Type C