The pair finished ahead of another Orica-GreenEDGE rider, Adam Blythe, at the end of the 207km stage from Muju to Yeosu. The top three riders now lead the general classification with Ewan ahead of Bevin then Blythe.
"I knew looking at the stage that the (distance) would play into my favour" Bevin said after the stage. "Outright, (Ewan) is extremely quick, but I was hoping that the distance and four days (raced so far) would have added up a bit.
"I've got one thing going for me on a sprint like this, I've got resilience and the ability to hold that power and I was just coming back through pretty quick."
With 207 kilometres of racing, and more than 30 riders within half a minute of the overall lead, a long and potentially combative day in the saddle awaited.
After resisting countless breakaway attempts, the peloton eventually permitted a break of five riders, Didier Alonso (Nippo-Vini Fantini), Gong Hyosuk (KSPO), Jeong Cheunggyo (Korail Cycling Team), Hamid Beykkhorzimi (Pishgaman Giant) and Kim Dohyoung (Seoul Cycling Team), to escape.
After 50km of racing, the quintet had extended its advantage over the peloton to eight minutes. Beykkhorzimi took the spoils from both KOM climbs to climb into first on the overall KOM classification, while Jeong tok out the day's intermediate sprint which split the two summits.
Behind, Orica-GreenEDGE, Drapac and Avanti Racing Team kept the break from building a greater lead and made the catch eight kilometres from the finish and controlled the sprint.
At the final right-hander with 600m to go, Avanti's Neil van der Ploeg found the perfect spot to deposit teammate Bevin, whose desperate sprint to the line secured him the narrowest of wins.
"It wasn’t a surprise. I know he’s quick from all of those results this year and last year, and obviously I’ve sprinted against him in the past few stages," Ewan said. "I always knew he was going to be a threat but, you know, he was quicker than me today and there was nothing I could do. I was sprinting as fast as I could and he came around."