You all (must) know that it is mandatory to enlist the army when you're in Korea and if you are a male of course. It's from the age 19 to 35 after that you MUST join the army. Of course it's an exception if you are sick or hurt. (Like, serious hurt or sick, serious...) *_*
You'll have to do some tests to see which level you are on. If want to know more klick Here

If you don't join the army you are concidered beeing a coward who doesn't keep your country "dear" (kinda...) 
There's some people who have done literally anything to escape the army. Everything from hurting themselves to escape to another country. Now you wonder "What the hell does this have to do with kpop?! bla bla and I've read this crap for nothing". Well just shut up and keep reading because here comes the interesting part.

A kpop artist that have done anything to avoid, join the army:

Yoo Seung Jun



He was "on his way" to enlist the army but became a U.S citizen. The government in South Korea consicered his action and deported him to the U.S and banned him from Korea. Pretty harsh...
This is only a short fact if you want to read more just Google his name or anyting!