KUNLP system for NTCIR-3 English–Korean cross-language information retrieval

This paper describes KUNLP system for the English-Korean cross-language information retrieval track in NTCIR-3 workshop and some experiments after the workshop. Query translation method based on the bilingual dictionary and the document language corpus was used. To automatically transliterate some proper nouns such as Korean person names, Korean place names, and Korean company names, we have constructed the bilingual biographical dictionary, and collected the corresponding translations of Korean place names and Korean company names. We submitted a monolingual run and three cross-language runs, which used only a description field of each topic as a query. Cross-language runs were classified as to whether query expansion was used and whether manual transliteration was applied. Comparisons between cross-language runs show that query expansion is useful in the English-Korean cross-language information retrieval and transliteration also improves the system performance. And additional experiments after NTCIR-3 workshop show that the Korean query which consists of the best translation equivalents for English query terms is more effective than that consisting of two or more translation equivalents. In addition, including English acronyms and initial words in the Korean query is helpful to retrieve Korean documents. Keywords: English-Korean cross-language information retrieval, query translation, query expansion, query transliteration.