Seoul, South Korea - Around 31,000 North Koreans have defected into the South since the end of the Korean War in 1953.

Almost 71 percent of those defectors are female, most in their 20s and 30s.

Only a few take the most dangerous route through the Korean Demilitarized Zone that a North Korean soldier took late last year.

Most of the North Koreans defect via the long and expensive journey that takes them into China after crossing the Yalu River.

The journey takes them to China's southern border into Vietnam and Laos before they arrive in Thailand.

They are often flown into South Korea from Thailand.

Some even opt to go to the US, according to Liberty in North Korea, an NGO based in the US and South Korea.

But their arrival into South Korea does not signal an end to their worries and problems.

Part 1 - 'Korean government doesn't treat defectors as people'

Part 2 - 'I wish I can go back to North Korea for a day'

Part 3 - North Korean defector describes life at home through cartoons

In part four of the series, Al Jazeera speaks to Um Yae-run, a 41-year-old defector who now works at a marriage bureau and also as a broker.

She describes the routes and costs associated with fleeing North Korea.

"My aunt lived in the border region and managed to flee to South Korea through China.

"Three years later, she contacted me through a broker to try to get me to come over. I pondered over it for about a month. I didn't want to leave but eventually, in 2009, left my daughter and mother and fled.

"The broker took me to the border but made me cross the river [at the border] in the middle of the day.

"It's not very big. There's a hole in the middle of the frozen river and North Koreans pump water to do their laundry there. I pretended to do the same and then the broker on the other side started yelling 'miss, put that down and run'. I heard that and ran.

"The border guards shot at me. I had learnt that you have to run zig-zag to avoid being shot and that's what saved me.

"From China, the broker took me to Vietnam. When we reached Hanoi we were in a motel for about four days. The brokers don't take one or two people but gather about 10 and move them together.

"We then took a train to the Cambodian border. We walked and then crawled for a kilometre, taking a road that was totally dark and empty except for some checkpoints.

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"We waited for three nights in Cambodia. We then rode in a car to get to a ferry that crossed the river and were driven to the Korean embassy. They moved us to a church where we stayed for three months.

"A lot of people who come to South Korea become brokers. They work with brokers in China who work with brokers in North Korea.

"If someone in the South wants to bring a family member over, they will give the address of the person in North Korea so the South Korean broker who will pass it on.

"In North Korea, you can't trust anyone who says he's a broker. So we give the brokers personal information, like a code word, so the person knows who sent the broker.

"The person will then work with the brokers to get you to the border. If you don't live near the border you need to take a train for which you will need a licence. The brokers will pay to get you on the train and bribe the railway officials.

"In North Korea, if you have money, you can do anything. Once at the border, the broker will arrange a time for crossing the river. In the summer, you might swim with a black rubber boat or the boat might have a string attached to the Chinese side that the brokers there will pull.

"The brokers might also bribe the border patrol to tell them their shifts so they can cross over then. If they can strike a deal, it becomes easy.

"When I crossed the border, it cost me around 3m Korean won ($2,800). When my daughter came, I paid 6.5m ($6,000). Now, it costs almost 10m won ($9,300). Coming to South Korea will cost you around 15m won ($14,000). Crossing the border is the most expensive part. Rest is cheaper.

"After arriving in South Korea, I was interrogated by the intelligence agency for a month before they let me out. I decided to work as a broker because for every person you help, you made around two to four million Korean won ($1,800 to $3,700).

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"The first person I helped flee was my daughter. My mother didn't want that. She wanted me to get married in South Korea and start over. I had many suitors but after I brought my daughter over, they all left.

"When I came here, I saved a lot of money. I didn't eat, I didn't buy anything expensive. My clothes cost me 2000 to 4000 won ($1.8 to $3.7) and I also wore clothes that others gave me. When you receive free money, you don't realise how it's made. My mother acted like she was the mother of some rich daughter.

"I'm not in touch with my mother now. My siblings are there with her so might be okay. Sometimes I feel bad that we're not in contact, like I'm being selfish, and I'm sorry to my parents.

"I now work at a marriage bureau. We pair up North Korean women with South Korean or other foreign men. We bring the girls through personal networks. If there are girls around me who are single, I'll just bring them over and tell them there's a good client in my company."

As told to Faras Ghani and Hae Ju Kang