Korean Air plans to launch a daily Busan-Hanoi service on 21 December.
The carrier will use Boeing 737-900 aircraft on the route, says a spokeswoman.
In addition, its Seoul Incheon-Dallas Fort Worth frequency will increase from five times weekly to daily, starting 13 May 2012.
As part of its winter schedule, the carrier has also increased the frequencies of four services from Seoul Incheon.
The airline has added a weekly flight to its Jinan and Zhengzhou services, increasing the frequencies to thrice and four times weekly respectively.
Its services from Seoul Incheon to Xian and Taipei Taoyuan have, meanwhile, increased from thrice to five times weekly and from 12 times weekly to twice daily respectively.
The carrier will also terminate its thrice weekly Seoul Incheon-Melbourne service on 4 March 2013. It will resume its twice weekly Seoul Incheon-Cairo service on 7 January 2013, adds the spokeswoman.