While acknowledging hardships adjusting in South Korea, Hyuk said: "I am very comfortable, because I can openly say anything."
He's anxious about what he'll do after he graduates from the school -- maybe he'll go into operating forklifts, Hyuk said.
A mop of shaggy bangs falls over his round face as Hyuk sits atop a table, his legs swinging freely.
"I can eat, live, and survive here."
Scars from trauma
Most North Koreans escape by crossing the river on the northern border to China. Some street children who flee to China become easy prey to traffickers, according to human rights activists.
The girls are sold into the sex trade, or as wives for rural Chinese men. The young boys are sold as sons into Chinese families who have not been able to produce one, said Jung of Justice for North Korea.
China sends back those escapees they catch, so defectors live in hiding -- fearing they'll be imprisoned and tortured back home.
That fear can continue long after escapees have made it to South Korea.
In the home of pastor Daniel Park, we met a 13-year-old boy whose mother took him to China when he was a year old. The mother was caught and repatriated to North Korea, but the boy remained in China, where he was beaten and abused, Park said.
In Park's Seoul home, the trauma showed. The boy, sporting a buzz cut, was skittish and jumpy around strangers and followed Park closely around the house. During mealtimes, when his foster family would gather to eat, he would take his food and hide in his bedroom and eat alone.
But Park said his habits have since improved.
Escape through China
As Yoon Hee entered adolescence in North Korea, her hopes of reuniting with her mother began to fade.
A few strangers would give money, others would give her food, shoes or clothes after taking pity on her.
"I had hope thinking that there were people out there who were willing to help me," she said.
Yoon Hee also ran errands for neighbors to earn change.
But in 2009, the North Korean government exchanged its old currency for a new one worth just 1% of its original value. It immediately wiped out people's savings and triggered chaos as prices for food became unreachable.
"At that time, so many people were dying," Yoon Hee said. "If I opened my neighbor's door, people were dead, collapsed on the floor. So many people headed for China, I thought that at least I could survive there."
There was nothing left for her in North Korea. Her hopes of reuniting with her mother finally faded.
So she made her first escape into China. In the wintertime, the river at the border freezes, paving the way for a quick escape.
In China, she said she was caught three times by local police and each time, she was sent back to a North Korean prison. She was pummeled with fists, sticks and kicked, Yoon Hee said. But each time, she was released, she said.
In early 2010, she escaped North Korea for the fourth time and eventually met Daniel Park through underground networks of Christian activists and missionaries
Funded by donors and ministries, the networks employ brokers who help refugees cross into China, bribing and using their connections with officials and border officers.
The networks reach Laos, Thailand and Vietnam, countries near China where the authorities will not repatriate North Koreans. From there, North Koreans try to find their way to a South Korean embassy -- where they are sent to Seoul -- or they seek refuge in the embassy of other countries like Canada, Britain or the U.S.