臺大管理論叢 NTU Management Review VOL.28 NO.3

91 NTU Management Review Vol. 28 No. 3 Dec. 2018 Table 1 Example of a User’s Preference Feedback and Time Spent on Documents Document ID Interest Rating Length of Document (words) Time Spent on Document (seconds) Average Browsing Time (seconds) 1 3* 116 173 1.491380 2 5* 113 97 0.858407 3 5* 79 66 0.835443 4 4 88 52 0.590909 5 2 223 119 0.533632 6 2 156 81 0.519231 7 3 98 50 0.510204 8 7 ★ 87 42 0.482759 9 4 ★ 113 38 0.336283 10 5 ★ 123 26 0.211382 Note: *The interest rating of the three documents with the longest average browsing time ★ The interest rating of the three documents with the shortest average browsing time 3.2 Document Concept Expansion In this study, we assume that the concepts within each individual document are readily available. As the documents of interest to the focal user are identified, the ICE technique seeks to discover relevant concepts by expanding the concepts that already exist in these documents. Specifically, the ICE technique adopts the spreading activation model to expand concepts on the basis of a domain concept heterarchy. As shown in Figure 2, the domain concept heterarchy is composed of a set of nodes and links. Each node represents a concept, and each link represents the relationship between two concepts. A directed link indicates an is-a relationship that implies an inheritance relationship between the two concepts (e.g., “1.1 Memory Structures” is a sub-concept of “1. Hardware”), while an undirected link shows a non-is-a relationship that implies a simple association between the two concepts (e.g., “1.1.2 Design Styles” is associated with “1.2.1 Design Styles”).