The southeast part of AK does have a peninsula.
North.
North Korea itself is not a peninsula. Along with South Korea it is on a peninsula known as the Korean peninsula. North Korea forms the start of it and South Korea is the end of the peninsula.
the Korean peninsula
South Korea occupies the south part of the peninsula, North Korea occupies the north part.
south
South.
North Korea and South Korea lie on the Korean Peninsula.
=South=
Korea is two countries (North Korea and South Korea) on a peninsula.
Upper Peninsula lies North of the Lower Peninsula.
The Asian Countries that occupy the Choson Peninsula (Hanguk Peninsula in South Korea, Korean Peninsula in English) are North Korea (the Democratic People's Republic of Korea) and South Korea (the Republic of Korea). This peninsula extends from Asia between the Sea of Japan & the Yellow Sea.
the Korean peninsula: includes both south and north Korea