INCHEON, May 18, 2014 (AFP) - The 28-year-old South Korean finished 11 under for the tournament -- one ahead of compatriots Lee Tae-Hee and Kim Kyung-Tae.
Australian David Bransdon also challenged down the stretch but had to settle for fourth place at nine under, while star attraction K.J. Choi ended a shot further behind.
The lead changed hands several times in a gripping final round -- at one point the top four were all tied at 10 under -- on a day where there were birdies aplenty, but also bogeys lurking around every corner.
Sharing the overnight lead with multiple-winner Kim Kyung-Tae, Kim Seung-Hyuk looked to have blown his chance with a double-bogey at the fourth, but birdies at five and seven got him back in the mix.
"I didn't panic after the double," he said in comments released by organisers. "There was still a lot of holes to come, so I just tried to focus on my game."
One group ahead, Lee birdied 17 and just missed another on 18 to post a 10-under par target, while playing partner Bransdon made amends for a dropped shot at 17 with a final hole birdie to finish one behind.
Kim Kyung-Tae fell away after dropping shots on 11 and 12, but back-to-back birdies on the next two -- as well as a birdie and bogey on 16 and 17 -- kept him in the hunt.
The Kims walked onto the 18th both needing a birdie for victory; Kim Kyung-Tae's 20 footer slid agonisingly by, while Kim Seung-Hyuk found the cup from nine feet.
"It was a fantastic feeling when it went in," he said. "Now I know I can win a golf tournament, so I can set my sights on winning more."
Final standings (South Korea unless stated)
277 - Kim Seung-Hyuk 66-74-67-70
278 - Lee Tae-Hee 68-68-73-69, Kim Kyung-Tae 70-70-67-71
279 - David Bransdon (AUS) 71-70-69-69
280 - K.J. Choi 75-67-70-68
281 - Lee Kyoung-Hoon 70-70-69-72
282 - Kim Dae-Hyun 72-69-75-66, Park Sang-Hyun 72-67-73-70
283 - Kim Nam-Hun 72-73-69-69, David Oh (USA) 74-70-69-70, Jang Dong-Kyu 75-66-70-72