Double Consonants:

*Note: They won't be in order... I'm still learning the order of the alphabet myself... so yeah... lol

ㅃ

It is a hard B.

As in Bat

pretty much if a romanization has two 'B' then you would use this... or it can be two 'P'

Example:

오빠 / Oppa

아빠 / Appa

빵 / Bbang (Bread)

ㅉ

It is a hard J.

As in Jjang

Example:

짜장면 / JjaJangmyun (Black bean noodles)

ㄸ

It is a hard D.

As in Ddeokbukki

Example:

떡볶이 / Ddeokbokki

딸기 / Ddalgi (Strawberry)

어떡해 (Eotteokhae)

*Note: Sometimes it can be romanized with two 'T's