In advance of its merger with another Koreatown bank, Center Financial Corp. late Thursday said that it had fired its chief executive, Jae Whan Yoo, and replaced him with a veteran Southern California banker.

Center Financial announced last month that it would merge in a roughly $286 million stock deal with Nara Bancorp Inc., creating the nation’s largest Korean-American bank. In the announcement, it said the new institution would be led by Nara’s current Chief Executive Alvin Kang with Yoo slated to serve as president.

But Center said that Yoo was “terminated” earlier today and a non-Korean, Richard S. Cupp, had agreed to serve as interim chief executive until the merger closed, which is expected in the second half of this year after approval by shareholders and regulators.

Yoo had been Center’s chief executive and president since January 2007, and earlier held the same positions at Hanmi Financial Corp. Cupp, 70, is a banking industry consultant and who has served as chief executive of several community banks, including 1st Century Bank, First Bank of Beverly Hills, HF Bancorp, and Ventura County National Bancorp. He is an alumnus of both USC and UCLA.

“We wish J.W. well with his future endeavors,” said Center Chairman Jin Chul Jhung in a statement. “We are delighted that an executive of Dick Cupp’s caliber will be leading Center Financial during this important transitional phase.”

The combined institution, which will operate under a yet-to-be-determined name, will have pro-forma assets of $5.3 billion and deposits of $4 billion, as well as more than 40 branches located primarily in California.