I served in the North Korean army for 10 years, so I have never needed an alarm clock. I’m awake around 5.30am, and sometimes I wake up angry because I’ve had a nightmare about my life before coming here.

The first thing I do is go for a run near my home. There are 8,000 defectors from the North living in South Korea now, and about 3,000 live around here. We have a stronger accent and it is difficult to find jobs because companies ask how they can trust us. Most of us never let anyone know where we live, but I don’t care any more: worrying changes nothing. And I don’t think North Korea would send a team over here to kill me. It would be too expensive for just one man.

I thought it was only a matter of time before North Korea would try to be recognised as a nuclear power. I don’t think Kim Jong-il will use his nuclear weapons against other countries, because he’s the richest man in North Korea and he doesn’t want to jeopardise his perks. The international community needs to be strong and stand up to Kim.

I never eat breakfast now. When I lived in the North, I made sure I never missed a meal because the next one was not a certainty. But here I can eat when I choose.

Instead, I read the newspapers for ideas for the radio programme. I’m in the office at around 8am and I spend the first hour searching the internet for information about North Korea. The rest of the staff arrive around 9am and we’ll have a planning meeting. We started with web-radio broadcasts in 2003, but last December we began short-wave programming. We will have to change frequency soon — the North Koreans keep jamming it. We are not allowed to broadcast directly into the North, so the programmes go through a British company and are re-broadcast via Mongolia, Vietnam and Russia. But we know people over there are hearing us; a survey showed 12% of defectors listened to us before deciding to go. Church groups and NGOs try to send radios and other aid over the border. When preparations are completed I go to the restaurant upstairs — the owner lets us eat there cheaply. It’s 500 KRW [South Korean won — about 28p] for a bowl of soup. My mother used to cook soya-bean-paste soup, but I can’t bear to eat it any more — it reminds me too much of my family in the North.

When I was born, my father had just been “revolutionised”; he had been a poet but the government sent him to work in a factory. I went into the military at 17 because we were poor and I could not go to university. I became a captain in the long-range artillery division. When stationed near the border, I could watch South Korean TV and listen to Radio Free Asia. Also we got South Korean propaganda leaflets. After the army, I went to teacher-training college. I finally decided to defect when Kim Il-sung died in July 1994. I chose a shallow stretch of the Tumen river on the Chinese border and waded across early one morning.

I had to avoid the military patrols. The guards shoot at people often, but I knew they were only blanks. Now I hear they use live rounds. My parents were both dead by the time I left, but I’m not sure if my sisters have been punished for my defection. I’m not in contact with them.

In China I found work in a brick factory and then in a Korean church, but after four years I was caught by the Chinese police and sent back. The North Korean border security officials tortured me.

For 10 days they beat me. They broke both my little fingers. I thought I was going to die. Then they put me on a train to Pyongyang with two guards. Because I had been an army officer I would have been publicly executed, so I jumped off the train from the toilet.

It took three days to get my handcuffs off, and nine days to walk back to the Chinese border. I got over the river again and when I took my first shower in a month I found 28 ticks beneath my skin. I hadn’t noticed. I broke down then.

Relatives in South Korea helped me get a fake passport and I flew to Seoul in February 1999. But immigration officials realised it was fake and I was questioned by South Korean intelligence for seven months, and by American officials. After my release, I worked for relatives before reading literature at graduate school. I then worked for a defectors’ association while I planned the radio station. I had some savings, my grandmother helped and I used the 150m KRW [£84,000] I got from the South Korean government as a defector — they gave me more than others because at that time I was the highest-ranking military defector.

Many people protest against what I’m trying to do. Students and left-wing groups have threatened me countless times. I’ve been knocked unconscious in the street and now there are two plain-clothes police outside. We have had to change our offices three times.

My afternoons are unpredictable. I do interviews or meet academics and journalists. I talked to George W Bush in April. He told me I was very brave and that he would do what he could; shortly after, he announced the US would let more North Korean defectors live there.

I have dinner with my family — my daughter does not know I am a defector. Sometimes I meet people and discuss Korean issues. I think when Kim Jong-il dies, North and South will be reunited.

I’m usually in bed around 10 — and I hope that I don’t dream.

Interview by Julian Ryall