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

Here is Why You Need An Adapter

The outlet and plug type used in Cuba are A, B, C and L 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

Cuba

In Cuba, outlets of type A, B, C and L are in use.

Type A

Type B

Type C

Type L