"I feel a deep sense of loneliness since neither my wife nor my kids are waiting for me," the 45-year-old administrator said of his home in the city of Cheongju, 120 km (75 miles) south of the capital Seoul. "There is only total darkness."

Choi is one of a growing legion of Korean fathers who send their families overseas when the children hit their teens, hoping to help them both escape the pressure-cooker South Korean educational system and learn English - which will help them get better higher education, and better jobs.

The wives go along with the children, leaving the fathers - known as "goose fathers" in local slang - behind to work and finance the whole venture.

"I sent my two sons, one in 9th grade and the other in 6th grade now, to Michigan with my wife last year," Choi said.

"I wanted them to enjoy their school years, experiencing a variety of things instead of cramming for exams throughout the year, which is what most students do here."

The "goose father" nickname refers to the seasonal visits made by the fathers to their faraway families, the way geese migrate every year. "Eagle fathers" are men wealthy enough to visit at will, while "penguin fathers" have no idea when the next reunion will take place.

The trend of families separating like this for education emerged in the late 1990s, with a growing desire to learn English and escape the relentless competitiveness of the domestic education system.

"When I was in high school, I saw my classmates about to throw up out of nervousness during exam periods, because we knew the names of the college we attended could be seen as a measurement of how well our parents had raised us by others in society," said Choi Hee-Kwon, a 23-year-old university student.

It is not rare for high school classrooms to be lit well past 10:00 p.m. so students can prepare for the annual CSAT exams that determine which universities they can attend. The nine-hour test is perceived as life-altering because it only takes place once a year.

Under the pressure, some students crack. At least 11 teens have taken their own lives over the past five years because of worries about grades, according to the Seoul Metropolitan Office of Education.

As a result, a growing number of parents hope to spare their offspring. The number of pre-college Korean students studying overseas has risen to over 18,600 in 2011 from 4,300 in 2000, according to the Korea Educational Development Institute, a government body.

But life is far from easy for all concerned, particularly the fathers left behind.

A survey of 151 of fathers with families overseas conducted in 2011 by Cha Eun-Jeong at Ewha Woman's University in Seoul found that 76.8 percent suffered from poor nutrition.

"The matter of their health condition closely correlates with whether they live with their parents. If they live alone, they display difficulties in consistent eating and weight loss," she wrote.

One out of three, or 29.8 percent, were in the early stages of depression, she added.

Many such fathers repair to bars, pouring out their tales.

"I have seen some regret making decisions over the sacrifice because of loneliness and depression," said Lee Jung-jin, manager of a Seoul bar. "Some even confided to me that they had become estranged from their wives since they had been apart for so long."

Even celebrity is no barrier to such suffering.

"When I arrived home after taking my family to the airport I saw flies in the kitchen," Kim Tae-won, guitarist in the popular rock group Buwhal, told local media.

"I was going to kill them but couldn't as I was feeling too lonely. Very soon the house became full of flies."

(Reporting by Elaine Lies)

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