For the past several decades, many researchers have been
exploring human emotions. In the early days, researchers tried
to define them in several categories and proposed many models
of human emotions for recognition and synthesis. Ortony
et al. established an emotion synthesis architecture of 22
conditions which influenced emotions and variables which
affected the intensities of the emotions[1]. From the study
of facial expression of emotions, Ekman defined six basic
emotions which has been widely used in field of psychology
and robotics[2]. Wilson developed his conceptual model by
categorizing human emotion into momentary emotions, moods
and personality[3]. Russell et al. proposed his noble idea
showing inter-relationships between affective concepts on the
spatial model in which the affective concepts fall in a circle[9].
In 1990s, researchers such as Arnold and Lazarus thought
that emotions are resulted from human evaluation of events
that cause specific reactions. T