Market-based resource management is becoming an emerging issue as the utilization of Grid computing is growing rapidly, particularly in the business field. In this paper, we provide a new Imprecise Computation Grid application model for flexible market-based resource management. Each job in a Grid application has two parts: mandatory part for the minimum quality and optional part for additional computations. This application model can be applied to QoS-related Grid applications and used in adaptive resource management. We also provide scheduling algorithms for resource allocation of IC Grid applications. Simulation results show that better utility is achieved when users specify both mandatory and optional requirements.