Abstract
A technical analysis was conducted to predict the development trends for heat pump system. This study was based on submitted patents from 1983 to 2002 in Korea, USA, and Japan. The total number of raw data from the registered database was 19,261 and the obtained data to be analyzed through the filtering process was 5,143. Japan's technical development for the heat pump system was more dominant than the other countries. Approximately $54\%$ of the total patents related with the heat pump system was registered by Japan. The number of patents for the heat pump system registered by Korea was very low in 1980's, but it increased rapidly in 1990's. As a result, the number of patents applied by Korea was $21\%$ of all patents. When the patent was categorized into compression, absorption/ad-sorption, and chemical type, the technology of compression type made up over $80\%$ in each country. Approximately $93\%$ of the patents surveyed in this study was developed for air or water source heat pumps because of easy applications compared with other heat sources. The $89\%$ of all patents was applied by companies when applicants were divided into three groups of company, individual, and the others (national institute, university, and so on).
