Páginas oficiales

Corea
http://kimjeonghoon.co.kr/
Japón
http://johnhoon.com

Especially, with http://kimjeonghoon.co.kr/, everybody can register there, you just need an email address :welcome:
Click on the button "Join us" and follow the process.
But everything is written in Korean, I'm afraid

Inside that page, there's a small part for paid member:
http://jand.hompee.com/
where there are many private videos and messages of Jeong Hoon. You can't join it at the moment, but you could pay to join next year

Official Websites/Fan Sites

http://ameblo.jp/johnhoon146 (Official JH blogsite, Japan)
http://jhworld.jp/ (Official Japanese HP online site)