It looks like this guy was trying to be a copy cat of the last wacko that tried this stunt on an Asiana Airlines flight a few weeks ago:
A passenger attempted to open the plane door during flight early Monday, the second such incident in less than a month after the shocking mid-air door opening accident on an Asiana Airlines flight.
The door did not open in Monday’s incident, and no one was hurt.
The unidentified passenger tried to force the door open on a Jeju Air flight that was on its way to Incheon from Cebu in the Philippines, according to the airline and online postings by passengers.
The Boeing 737 plane, carrying about 180 passengers aboard, had departed from Cebu at 1:49 a.m.
About an hour into the flight, the passenger began to act strange, complaining he felt pressure on his chest, according to Jeju Air.
The flight crew offered to move him to a seat near the jump seats, but he continued his abnormal behavior and ran toward the exit to force the door open.
The flight attendants and some other passengers subdued the passenger, three hours before landing, and the person was immediately handed over to the Incheon airport police afterward, Jeju Air said.
Yonhap
You can read more at the link.