In Korea, variolation (inoculation with Variola pus) and cowpox vaccine have been understood from the perspective of superiority and inferiority, but recently, the modernity and historical role of variolation are being re-examined. In addition, the role of Jeong Yak-yong(1762-1836), who introduced both variolation and cowpox vaccine, is also drawing attention in the process. However, the foundation for the spread of variolation and cowpox vaccine in Korea was very weak. This was due to a combination of several factors, including political repression against Western studies, and lack of medical knowledge networks as well as of public support and technology for securing and inoculating vaccine lymph. Among them, this article focuses on the importance of the original technology, which has been overlooked in the research on vaccination, such as the collection, storage, and inoculation technology involving vaccine lymph. Without vaccine lymph, vaccination is impossible. In the case of variolation, there was no difficulty in securing vaccine lymph as it was collected from a smallpox patient. However, in the case of cowpox vaccine, there was a problem of stability and technical difficulty in term of matured and freshly extracted vaccine lymph. In the case of cowpox vaccine, it was necessary to secure cowpox lymph, but until the first half of the 19th century, there was no way to secure cowpox lymph in Korea. It was impossible to produce on its own, and the cowpox lymph imported from abroad became rotten and thus ineffective. Unless vaccine lymph was secured, no matter how good the inoculation method was, it was useless. Variolation and cowpox vaccine were in a relationship of succession both theoretically and technologically. However, to be precise, what was used in cowpox vaccine was not Chinese-style, but Turkish-style(or Western-style) variolation. Whereas Chinese-style variolation was a method of blowing vaccine lymph into nostrils, Western-style variolation was a method of making an incision on the skin of the forearm and inoculating vaccine lymph in the incised area. Therefore, in order for the Chinese-style variolation to evolve to cowpox vaccine, it was necessary to explain and persuade why vaccine lymph should be inoculated and why the skin of the forearm should be incised. In Korea, the evolution of variolation to cowpox vaccine met a major obstacle due not only to political, social, and medical doubts but also to medical and technological factors such as the transmission of technology to secure and inoculate vaccine lymph.