Subject World: A System for Visualizing OPAC
HARUMI MURAKAMI, † TAKASHI HIRATA†† AND KATSUICHI KITA†
Requirements for subject retrieval in OPAC have recently expanded. Librarians hadcreated tools such as subject catalogs and classified catalogs to search documents basedon their contents. However, most users are unaware of the existence of the catalogs, or do
not know how to use them. In addition, there are few available OPAC systems fromwhich the user can retrieve these catalogs. In this paper, we propose a system thatvisualizes heterogeneous terminology including catalogs, enabling users to operate themfor subject retrieval in OPAC. We will also describe a prototype system called ``SubjectWorld'', in which the user can browse and operate BSH4 subject headings and NDC9index terms, and search by subject headings from Osaka City University's OPAC.

1. Introduction
Requirements for subject retrieval inOPAC have recently expanded. Librarians
had created tools such as subject catalogs
and classified catalogs to search documents
based on their contents before the age of thecomputer. Nowadays, though, the user cansearch documents by inputting terms intoOPAC. However, most users are unaware of
the existence of the catalogs, or do not know
how to use them. In addition, there are few
available OPAC systems from which the user
can retrieve these catalogs.
We propose a system that visualizes
heterogeneous
terminology
includingcatalogs, enabling users to operate them for
subject retrieval in OPAC. The system helps
users to: (1) retrieve OPAC by showing
related terms; (2) reorganize retrieved
information by enabling users to operate
displayed objects; and (3) understand subject
catalogs and classified catalogs in OPAC.
We have developed a prototype systemcalled ``Subject World'' in which the user canbrowse and operate BSH4 (Basic SubjectHeadings) subject headings and NDC9(Nippon Decimal Classification) index terms†††

Media Center, Osaka City University
Japan Ground Self Defense Forceand retrieve information from Osaka City
University's OPAC (hereafter OCU-OPAC).
In this paper, we describe the overview ofthe Subject World.

2. Subject World
Subject World is a prototype system inwhich the user can browse and operate
BSH4 subject headings and NDC9 indexterms, and retrieve information fromOCU-OPAC.
The system database is constructed of“objects” that the user can operate, and“links” that have semantics between objects.
There are two kinds of objects: “concepts” and“documents.” Currently the system deals
with Japanese books contained in OPAC as
documents. There are two kinds of links: thesemantics between concepts, and links
between concepts and documents.
We have implemented two methods for
integrating heterogeneous terminology.
Figure 1 shows the framework ofintegrating heterogeneous terminology.
(1) between BSH4 and other subject headings
via OPAC(1a) from concepts (BSH4 subject headings) to
documents in OPAC by “search by subjectheadings” function in OPAC
(1b) from documents in OPAC to other subject

headings by checking subject fields in OPAC
(1c) from subject headings in OPAC toconcepts (BSH4 subject headings) bypattern-matching the labels(2) between BSH4 subject headings andNDC9 index terms(2a) from concepts (BSH4 subject headings) toconcepts (NDC9 index terms) by using NDC9index numbers contained in BSH4 subjectheadings(2b) from concepts (NDC9 index terms) toconcepts (BSH4 subject headings) bypattern-matching the labels

Concept(BSH4 subjectheading)Searchby subject
headings

OPAC(1a)subject
heading(2a)NDC9numberPatternmatching(2b)Concept(NDC9 indexterm)

Checking Subject fields
Patternmatching (1c)subjectheading(1b)Concept(not specified)(Broader Term) “ 情 報 理 論 (InformationTheory)”, and an NT (Narrower Term) “エキスパート システム (Expert System).”
Although it is difficult to search subject
headings that are not linked each other in
BSH4 database, Subject World can link subject
headings including BSH4, BSH3, and NDLSH(National Diet Library Subject Headings) thatare not linked directly in the BSH4 database byconnecting to OPAC.
Information
ScienceOsaka City University OPAC

Information
Information
TheoryProcessing
Artificial
Brain
Artificial
AI Intelligence
Expert System
Logic

Psychology

Thinking
Creativity
BSH4

Document(Japanese book)

Fig. 1: Framework of integrating heterogeneous
terminology.

2.1 Example
We present an example of the integrating
method (1). Figure 2 shows a BSH4 subject
heading “人工知能 (Artificial Intelligence)” in
BSH4 subject catalogs 1).
ジンコウチノ 人工知能 (Artificial Intelligence)⑧ 007.1 ⑨ 007.13 (NDC9 index number)
UF：人工頭脳 (Artificial Brain). ＡＩ
TT：情報科学 (Information Science) 121
BT：情報理論 (Information Theory )NT：エキスパート システム (Expert System)
Fig. 2: BSH4 subject heading “人工知能 (ArtificialIntelligence)”

Subject headings that are linked directlyfrom the BSH4 subject heading “ 人工知能(Artificial Intelligence)” are UFs (Use For) “人工頭脳 (Artificial Brain)” and “ＡＩ”, a TT (TopTerm) “情報科学 (Information Science)”, a BT

Information Processing(BSH4, NDLSH)
Artificial Intelligence(BSH3, BSH4)
Cognition (BSH3)
Recognition (NDLSH)
Cognitive Science (NDLSH)
Thinking (BSH4, NDLSH)
Document

Fig. 3: Overview of example 1.

Figure 3 shows an overview of the example
and a screen example is shown in Figure 4.
When a user selects a concept object “人工知能 (Artificial Intelligence)” and executes“search BSH4 subject headings” in a main
window, subject headings such as “人工頭脳(Artificial Brain)” “ＡＩ” “情報理論 (InformationTheory)” “ エキスパート システム (ExpertSystem),” are displayed as concept objects.
When the user selects the object and executes“search by subject headings” in OPAC, thesystem connects to OPAC, and retrieves
documents (Japanese books) that have subject
headings “人工知能 (Artificial Intelligence),”and displays search results in a “search results”
window. When the user selects a document, anicon representing the document object isdisplayed in the main window. One document
has subject headings “ 人 工 知 能 (ArtificialIntelligence)” (contained in BSH4 and BSH3),“ 情報処理 (Information Processing)” (BSH4and NDLSH), “思考 (Thinking)”(BSH4 andInformationScience

Artificial Brain

Psychology

Information
TheoryArtificialIntelligence

Logic

Search Results
WindowInformation
Thinking
Processing
Cognitive
CreativityScience

BSH4 subject heading
BSH4 subject heading（Bottom term）
Subject heading
Except for BSH4
NDC9 index term
（TT: Top term）
NDC9 index term
NDC9 index term
（Bottom term）

Cognition
Expert System

BSH4 subject heading（TT: Top Term ）Recognition

Document（Japanese book）

Main Window

Internet Browser

Bibliographic Information Window
Fig. 4: Screen example of example 1.

NDLSH), “認識 (Recognition)”(NDLSH), “認知科 学 (Cognitive Science)” (NDLSH), “ 認 知(Cognition)” (BSH3). When the user selects thedocument object and executes “search BSH4
subject headings,” these are displayed asconcept objects. In addition, the user can search
BSH4 subject headings “情報処理 (InformationProcessing)” and “ 思 考(Thinking).”
Furthermore, the user can search a BT “情報科学 (Information Science)” via “ 情 報 処 理(Information Processing),” and BTs “論理学(Logic)” and “心理学 (Psychology)” and an NT“創造性 (Creativity)” via “思考 (Thinking).”Note) and SA (See Also) were successfullydisplayed.
As of May 2001, in OCU-OPAC, 101,969
Japanese books have more than 2 subject
headings from a total of 359,479 Japanesebooks (28%)1. Likewise, 91,035 foreign books
contain more than 2 subject headings from atotal of 291,255 foreign books (31%). In asense, the probability of displaying othersubject headings by selecting a document is
28% in Japanese books and 31% in foreignbooks.

3. Related Work
2.2 Investigation
We make Subject World open to the publicfrom the authors web site2) and perform
preliminary experiments.
We describe an investigation about
displaying BSH4 subject headings andsearching subject headings in OCU-OPAC.
BSH4 subject headings except for SN (Scope

In the library world, Kita had proposed anidea of integrating subject catalogs andclassified catalogs for subject retrieval, however,
the idea was not implemented3). Currently insome systems such as the National Diet

The subject headings contained in the OCU-OPAC
are mainly imported from other cataloging databases.
1Library Web-OPAC 4) and Watanabe’s
BSH-OPAC 5), subject retrieval using BSH4
and NDC9 is available. Subject World isdifferent from them in that it can display therelationship between heterogeneous terms, andthe user can operate them.
In the field of Computer and Information
Science, there is much research concerning
integration and visualization of concepts. We
think that the significance of our research is (1)that new findings can be brought about
concerning how to deal with real data in thelibrary world, and (2) that Subject World is thefirst prototype for visualizing BSH4 subject
headings and NDC9 index terms.

4. Summary
We have proposed a system that visualizes
heterogeneous terminology including catalogs,
enabling users to operate them for subject
retrieval in OPAC. A prototype system called
Subject World in which the user can browse
and operate BSH4 subject headings and NDC9index terms, and retrieve information fromOCU-OPAC was described. We think that thesignificance of our research is (1) that newfindings can be brought about concerning how
to deal with real data in the library world, and(2) that Subject World is the first prototype forvisualizing BSH4 subject headings and NDC9index terms.
We need to improve the user-interface andadd functions, and perform a user-study to
optimize Subject World.
Acknowledgements
Acknowledgements We would like to thank theJapan Library Association for providing us with
BSH4-ComputerFile before its official release. Wewould also like to thank Mr. KOJO, Tsuyoshi andMr. TAMURA, Toshiaki at the Media center,
Osaka City University for investigating subject
headings contained in OCU-OPAC.

References
1) B.S.H. Basic Subject Headings 4th edition, theCommittee on Subject Headings of the Japan
Library Association, 1999.
2) Subject World Homepage,
http://www.media.osaka-cu.ac.jp/~harumi/researc
h/SubjectWorld/
3) Kita, K., and Shiba, M.: An attempt to integrate
subject indexing and retrieving tools in Japan,
Technical Processing & Documentation ForumSeries, pp. 6-31, 1994.
4) National Diet Library Web-Opac,
http://webopac2.ndl.go.jp/
5) Watanabe, T.: BSH niyoru OPAC no Shudaikensaku (Subject retrieval of OPAC by usingBSH), H9 NACSIS seminar research report, pp.
33-134, 1998.
Harumi Murakami received a B.A. from Kyoto
University in 1986, an M.Sc. from University ofManchester Institute of Science and Technology in
1994, and a D.Eng. from Nara Institute of Scienceand Technology in 1998. She worked for Fujitsu
Limited as a systems engineer from 1986-1995.
She is currently Associate Professor of the Media
Center, Osaka City University.
Takashi Hirata received a B.Eng. from theNational Defense Academy in Japan in 1993, anM.Eng. and a D.Eng. from Nara Institute ofScience and Technology in 1998 and 2001,
respectively. He joined Japan Ground Self Defense
Force in 1993.
Katsuichi Kita received a B.A. from Osaka City
University in 1972, and an M.Sc. from Osaka
Kyoiku University in 1996. He worked for Osaka
Institute of Technology and Setsunan University
as a librarian from 1972-1995. He is currently
Professor of the Media Center, Osaka CityUniversity.