Abstract
It is extremely important for developing a completely new product to predict its conditions of use and expected formance. Even if these are not clear a preliminary design Based be defined based on assumptions as to the operating conditions. Based on the preliminary design, a prototype of the product may be developed, and this can be evaluated by function and performance tests and also reliability tests under various alternative conditions to determine whether the product will meet the various conditions required. If the prototype does not meet the requirements or conditions, it is necessary to improve it and to check or review the adaptability of the operating conditions and the specification of the original design. It is the required specification of a new product that finally determines whether the design is satisfactory or not. If the target is a more complex product, such as an implantable artificial heart, it is more difficult for an engineer to make decisions by himself. In this case a contact point between medical science and engineering is necessary, and it is necessary to develop a specification which is the result of a consensus among the experts of the medical field.
