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

Here is Why You Need An Adapter

The outlet and plug type used in South Africa are C, M and N 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

South Africa

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

Type C

Type M

Type N