Abstract
This paper proposes case-based design aid using similarity between design cases. First, design cases and design modification cases are described by physical quantities and their calculations to represent physical phenomena and terms to explain them. Then, a quantity dimension space defined by nine fundamental and supplementary quantities in SI is introduced and similarity between physical quantities is mathematically defined in the space. Also, similarity between terms is defined by combining literal similarity and cooccurrence statistics. Finally, similarity between design (modification) cases is defined based on quantity- and term-similarities. By using design case similarity, designers can retrieve and consult the similar or relevant cases to a new design problem. Also, design modification knowledge such as "which physical quantity or design parameter should be modified to solve specific trouble" can be extracted by analyzing recorded design modification cases. The proposed methods are implemented as a Lisp program and examined through some examples.
