Only a handful of the railway operator's train services were running normally, with freight trains seeing the biggest decline.
Just 36 percent of them were in operation on Wednesday.
The nation's transport minister pinpointed the nation's rail operator as an example of lax management saying the plan to set up a subsidiary for new high-speed train operations is aimed at tackling that very problem and NOT at privatization.
"This strike stands against government policy. It is not justified nor does it have a practical interest. People need to get back to work before it's too late."
Experts say that if the strike extends for a long period of time, there could be a major supply shortages at industrial sites in the country, as most of the heavy industries rely on trains to transport supplies.
KORAIL has 24-thousand employees, but about 30 percent are currently on strike.
About 5-hundred people have returned to work since the walkout began, but only a handful are engineers.
The union workers are protesting what they believe is a first step by the government towards privitization of the state-run railway operator.
KORAIL has already removed about 68-hundred workers who have gone on strike from their positions.
Kim Hyun-bin, Arirang News.