When checking out the line-up of top drama stars this year, fans may notice that many of the hottest stars are approaching the age when they are required to enlist. In South Korea, males between the ages of 18 and 35 have to serve in the military for two years. Most prefer to serve before 30. And that's often when these stars are at the height of their popularity.

A few favorite k-drama actors have a date in mind while others have already taken their physical entrance exam but have no definite plans.

For example, Kim Soo Hyun, 26, the star of "You Who Came From The Stars" had his physical exam in 2012. The exam determines if a candidate has health problems that might prevent serving. He passed his exams but he has no immediate plans.

Choi Jin Hyuk, who played Lee Min Ho's older brother in "The Heirs" and an emergency room intern in "Emergency Couple," passed the exams required to serve his military duty as a conscripted policeman in the 47th Seoul Police Promotional Unit of the police corps. He plans to work for another year or two before enlisting.

Yoo Ah In, 27, on the other hand will probably enlist this year. The actor is currently starring as a piano prodigy in "Secret Love Affair" and said that the drama is his last before he enlists. He also originally wanted to apply for the police promotional unit but decided instead to serve in active duty.

Kim Hyun Joong, currently starring in the drama "Inspiring Generation," is 28. Unconfirmed rumors said that the actor plans to enlist in October. Jang Geun Suk, the star of "Pretty Man" is also rumored to be enlisting this year.

Lee Jong Suk, who last year had a hit with "I Hear Your Voice" and is currently filming "Dr. Stranger," is only 24. But he has already reported for a physical exam at the Seoul Regional Military Manpower Administration Office.

Lee Seung Gi, who will soon appear in the drama "You're Surrounded," has said he plans to enlist soon but advertising contracts have made it difficult to pinpoint a date.

2PM's Taecyeon, who is currently appearing in the weekend drama "Wonderful Days," plans to enlist in 2016. He did not have to serve as he was an American citizen and had physical problems. However, he renounced his citizenship and treated his physical problems so he could serve.

That leaves Lee Min Ho and Park Yoochun. Lee Min Ho, 26, has not made plans to enlist. JYJ's Park Yoochun, who currently stars in "Three Days" has had three physical exams and was categorized as a reserve member because of his asthma. That means the 27-year-old actor will serve as a public service worker. His fellow JYJ members Kim Junsu and Kim Jaejoong have also had their physical exams.

It's hard to imagine drama casting if all these stars enlist around the same time.

Fortunately, Yoo Seung Ho and Song Joong Ki will finish their military duty in 2015.