Abstract: Function is gradually recognized important
within the AI community, since this is the bridge
between human intention and physical behavior of artifacts
particularly at conceptual design stage. However,
to support conceptual design, there are two
research topics; namely, knowledge representation
scheme that allows a user to describe functions flexibly
without reference to behavior and structure and
a CAD system that supports the design process in
which functions are gradually embodied into behavioral
and structural models. This paper proposes a
new knowledge representational scheme for functions,
called Function-Behavior-State (FBS) modeling, that
defines afunction as an association of human intention
and behavior and represents a design object hierarchically.
For clarifying advantages of the FBS modeling,
we describe a computer tool, called an FBS Modeler,
that supports the conceptual design. We also formalize
design processes with this modeler and describe
an innovative application that increases reliability of
design objects by using functional knowledge.