This book deals with knowledge management with an emphasis on knowledge risk, i.e., a general trend of knowledge value getting shorter and becoming temporary. The shortening of knowledge value lifespan will have a profound impact on companies' employment policies, and employees' strategies for gaining knowledge.How to manage knowledge selection, including personnel management, will be the key to survival for companies, when corporate competency shifts from stable business contacts to the quality of their offers, and when the value of knowledge, which is the foundation of products and services, is becoming more and more short-lived. Work-sharing and human resource derivatives are thus proposed as new concepts in order to deal with knowledge selection risk.