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

Here is Why You Need An Adapter

The outlet and plug type used in North Korea is C and in South Africa are C, M and N. This is how they look like.

South Africa

In South Africa, outlets of type C, M and N are in use.

Type C

Type M

Type N

North Korea

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

Type C