Yongyeok violence has even featured in Korean pop culture. Last month, a well-known artist published a cartoon strip depicting a college student who works as an errand man to pay his tuition.
Bar owner Carmen Lee says she has endured real yongyeok intimidation first-hand. Since a dispute with her landlord, she says, she and her terminally-ill daughter have been harassed.
"These tough guys peer inside the bar window and yell at customers to bully them and make them scared." She said she was hit with a bottle opener and assaulted by one man.
Lee reported the incidents to police but has seen no letup. So she installed a surveillance camera in her bar to collect evidence and has developed a network of friends she can call at night when she feels outnumbered or intimidated.
"My daughter is my weakness. If I want to keep my business, I know I have to be strong, but I'm often alone," she said. "I don't know how much longer I can hold out."
For months, Insadong street vendor Sohn Byeong-cheol, who sells red-bean paste pastries, thought he had a lucky charm against yongyeok violence. Sohn, 54, and his wife are deaf and mute, and he was once singled out by President Lee Myung-bak for his hard work despite the physical challenges he faces.
With his cart bearing the president's signature, Sohn figured the yongyeok would leave him alone. But this month, several errand men surrounded his cart, hauling it away and turning it over to the city.
A newspaper photo here showed Sohn squatting on the pavement, wiping away tears of frustration, unable to call out against his attackers, who have vowed to keep up the pressure until the vendors give up their spots.
"I'm afraid of them," Sohn wrote in response to a reporter's question just days before losing his cart. "I'm always aware. Because I know they'll come back."
Jung-yoon Choi of The Times' Seoul bureau contributed to this report.