Abstract
This paper proposes computerized methods of case-based design aid using similarity and relevance between design cases. First, we introduce methods of describing and recording design cases and design modification cases by physical quantities and their calculations to represent physical phenomena and terms to explain them. Then, we introduce a quantity dimension space defined by nine fundamental and supplementary quantities in SI. In quantity dimension space, a distance between physical quantities is mathematically defined based on city-block distance, and then physical quantity similarity by dimension is defined using the physical quantity distance. Then, similarity between physical quantities is defined by combining the similarity by dimension and similarity of quantity calculation structures. Also, similarity between terms is defined by combining literal similarity and cooccurrence statistics. Finally, similarity between design (modification) cases is defined based on physical quantity similarity and term similarity. By using design case similarity, designers can retrieve and consult the similar or relevant cases to a new design problem in a design case library. 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 and clustering them using design (modification) case similarity. The proposed methods are implemented as a Lisp program and are examined through some examples.
