seoul, south koreaLee Min-bok’s home , some 25 miles south of the 38th parallel that divides North and South Korea, is built out of shipping containers. In his driveway, he parks a five-ton secondhand truck, the bed of which is laden with a large hydrogen tank. The vehicle is a vital tool for Mr. Lee’s life’s work. Mr. Lee counts himself immensely blessed to be living in South Korea. In 1991, he escaped from his native North Korea.