You Do Need power plug adapter while traveling from South 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 South Korea is F. This is how they look like.

South Korea

In South Korea, outlets of type F are in use.

Type F

Cuba

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

Type A

Type B

Type C

Type L