Most mainstream historical accounts of South Korea’s technological development have portrayed the 1970s as the period when the ‘seed’ of high-tech industries such as semiconductors was sown in its ground. This paper challenges this notion by asking how the soil for budding high-tech industries was prepared not only formally but informally. It aims to reveal the process through which the now-invisible but broad technological culture provided the historical context for the development of formal R&D and industry. During the turmoil of the series of wars in the 1940-50s, military supplies released from the United States’ military camps to major popular markets and radio repairshops to the technological culture of amateur radio activity were dismantled, distributed, and reassembled. This paper approaches such an informal process of technology introduction as an entangled history constructed through interactions between amateur and expert, non-institutional and institutional activities, and culture and industry. This approach will shed light on the existing notions of R&D, innovation, and localization in South Korea’s history of science and technology as historical constructs from such entanglement.