You Do Need power plug adapter while traveling from Cocos (Keeling) Islands to North Korea.

Here is Why You Need An Adapter

The outlet and plug type used in North Korea is C and in Cocos (Keeling) Islands is I. This is how they look like.

Cocos (Keeling) Islands

In Cocos (Keeling) Islands, outlets of type I are in use.

Type I

North Korea

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

Type C