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Korean script searching in Korean Library OPACs Junglim Chae Yonsei University Slide 2 Indexing Method N-Gram Morphological Analysis Slide 3 N-Gram Indexing N-Gram : Unigram, Bigram, Trigram, N-Gram E.g.) 12 Index by Bigram Segmentation , , , 0, 0 , , 0, 0 , , , , Many index terms-many results but lots of noise High recall ratio but low precision ratio Slide 4 Morphological Analysis Requires a morphological analysis dictionary E.g.) Three Index by morphological analysis , , Ability to match linguistically similar terms Faster performance with a smaller index Accurate matches that meet user expectations High precision ratio but low recall ratio Slide 5 N-Gram Vs. Morphological Analysis N-GramMorphological Analysis Recall RatioHighLow Precision RatioLowHigh Size of IndexBigSmall Indexing SpeedFastSlow Search SpeedSlowFast ApplicationLibrariesWeb Search Engines Slide 6 A Case Study Yonsei University Library Library System: Maestro-Y Search Engine: K2 by Verity Indexing Method N-Gram (bigram) + Morphological Analysis Indexing Rules Rule1: Divide Strings by space Rule2: Extract index using bigram indexing method Rule3: Add the whole string excluding spaces between strings Rule4: Add words from Korean morphological analysis dictionary Slide 7 A Case Study Yonsei University Library E.g.) / (rule1) , , , , (rule2) (rule3) (rule4) Index: , , , , , , Slide 8 Slide 9 Slide 10 Search Tips Slide 11 Search Tips(1) Keyword Search , Default Search Option Use at most 3 keywords Use Boolean operators Omit Stop-words Slide 12 Search Tips(2) Keyword Search Follow the Korean Word Division Rules E.g.) (O) (X) Slide 13 Search Tips(3) Keyword Search Compound Nouns do not use spaces between nouns E.g.) (O), (X ) Slide 14 Slide 15 Browse Search Begin with or Truncation , When you already know the first word of the title, author, or publisher E.g.) Search Tips(4) Slide 16 Slide 17 Browse Search Korean Classics E.g.) Search Tips(5) Slide 18 Slide 19 Slide 20 Exact Match Precise Search Known items E.g.) Search Tips(6) Slide 21 Slide 22 Exact Match Single character words E.g.) , , C Search Tips(7) Slide 23 Slide 24 Slide 25 Support Hangul/Hancha Searching E.g.) / Search Tips(8) Slide 26 Slide 27 Japanese Kana Archaic Korean Russian Special characters : Choose scripts from Multi-language Input Table Search Tips(9) Slide 28 E.g.) Multi-Script Input Table Slide 29 Japanese Kana / / Search Tips(10) Slide 30 Slide 31 Personal names ; Shakespeare ; Murakami, Haruki ; ; , Search Tips(11) Slide 32 Slide 33 Space Considered as AND E.g.) = AND In some OPACs, spaces in the character fields do make a difference in retrieval Search Tips(12) Slide 34 Slide 35 Slide 36 Slide 37 Slide 38 Comparative search with and without space Input Keywords Libraries National Assembly Library102 Spaces do not matter National Digital Library2,047 KERIS (monographs)3,246 Seoul National University Library171 Korea University Library224 The National Library of Korea614400 Spaces matter Yonsei University Library332179 Sungkyunkwan University Library14170 Ewha Womans University Library221133 Hanyang University Library344181 Slide 39 Thank You junglim.chae@yale.edu