Knowledge workers' workload to register knowledge can cause quality defects in the quality as well as the quantity of knowledge that must be accumulated in a knowledge management system(KMS). To enhance the availability of a KMS by acquiring more quality-guaranteed knowledge, autonomous knowledge acquisition which outdoes the automated acquisition must be initiated. Adopting the capabilities of context-awareness and inference in the field of context-aware computing, this paper intends to autonomously identify and acquire knowledge from knowledge workers' daily lives. Based on knowledge workers' context information, such as location, identification, schedule, etc, a methodology to monitor, sense, and gather knowledge that resides in their ordinary discussions is proposed. Also, a prototype systems of the context-based knowledge acquisition system(CKAS), which autonomously dictates, analyzes, and stores dialogue-based knowledge is introduced to prove the validity of the proposed concepts. This paper's methodology and prototype system can support relieving knowledge workers' burden to manually register knowledge, and hence provide a way to accomplish the goal of knowledge management, efficient and effective management of qualified knowledge.