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의료정보검색 (Information Retrieval). 2003. 9. 24. 최진욱. 정보검색이란. Information Retrieval 원하는 정보를 찾는 것 Data retrieval vs. Information retrieval. What is IR?. Information Retrieval is a science which deals with the knowledge representation, storage, organization and access of information items. - PowerPoint PPT Presentation
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(Information Retrieval)2003. 9. 24.
Information Retrieval Data retrieval vs. Information retrieval
What is IR?
Information Retrieval is a science which deals with the knowledge representation, storage, organization and access of information items.
Need for Information Retrieval ? ?Index, search ? ? ?
NLM and Medline10 million articles3,500 journals since 1966PubMed, Internet Grateful Medhttp://www.nlm.nih.gov
IR InternetSearch EngineVocabulary SystemInformation ModelingFiltering and Classification Natural Language Processing.
InternetTCP/IP networkpublic(not free, but open to everyone)carrier of electronic mailconvenient to get free SWterabytes of informationdynamic rerouting
Telephone network
?Another network
ARPAnet TCP/IP
Network in early stage
Protocolrules of behavior
: : TCP/IP2 widely used network protocols : computer network 100 TCP/IP
Internet AddressNetwork Host 32 bit8 ~ 24 bit
Internet Classes
E-mail [email protected]
URL
Hypertext
DNSDomain Name System(DNS) IP
www.kyobobook.co.kr 203.112.118.101www.cnn.com 198.137.240.92
Search engine News group Mailing list
Internet Search Enginewww.yahoo.com www.yahoo.co.krwww.altavista.comwww.altavista.co.krwww.excite.comwww.lycos.com, www.lycos.co.kr
www.dreamwiz.comwww.naver.com
Internet Search Engine
() . . . () . 1~2 .
. . .
AND searchSearch for Monet AND RenoirSearch for +Monet +RenoirSearch for Monet RenoirAll the words option
OR searchSearch for UPS U.P.S.Search for UPS OR U.P.S.Search for UPS U.P.SAny of the Words option
foreign policy vs foreign policy
NOT searchSearch for bugs life -antsSearch for bugs life NOT antsSearch for bugs life AND NOT ants
Near SearchKorea NEAR climateAltavista (advanced search)two terms within 10 wordsKorea NEAR climateLycos (advanced search)two terms within 25 words
USENET
- USENET system - news group USENET news server in SNUnews serverin Melbourne
Newsgroup Search Engine
Mailing list automatic mailing programs LISTSERVMajordomocomputer & privacytravel, weather
IR Modeling
IR stepsText processingIndexinginverted filesignature fileOrganization in DBQuery processingEvaluation
Information-Retrieval ProcessContentDatabaseInformationNeedQueryResultIndexingQueryFormulationRetrievalEvaluationRefinement
Indexing Processdocumentaccentspacingstopwordnoungroupstemmingautomaticor manualindexingstructurerecognitionfull textindex terms
Classification of IRUser
TaskRetrieval:AdhocFilteringBrowsingClassic ModelsbooleanvectorprobabilisticStructured Modelsnon-overlapping listsproximal nodesBrowsingFlatStructure GuidedHypertextSet TheoreticFuzzyExtended BooleanAlgebraicGeneralized VectorLat. Semantic IndexNeural NetworkProbabilisticInference NetworkBelief Network
Boolean Modelquery can be written in disjunctive normal formq = ka (kb kc)qdnf = (1,1,1) (1,1,0) (1,0,0)KaKcKb
Vector Model and Weight functionK = {, 2000cc, , , , kt}D1 = {20, 20, 11, 5, ,5}D2 = {20, 18, 12, 4, , 5}D30 = {0, 20, 12, 3, ,9}weight terms are assumed to be mutually independent !
Boolean vs. Vector modelPetroleum Mexico Oil Texas Refinery Ship
(1 1 1 0 1 0)
(2.8 1.6 3.5 3 3.1 1)Boolean
Vector
Retrieval IssuesIndexinginverted fileRankingrelevance rankingchronology rankingDisplay(aspirin, prevention)(prevention, )(aspirin, attack, heat)
: 27750177 : 20022777035 : RC102: Brain CT (Pre contrast) : Infarction Of Posterior Cerebral Artery Territory : 2002-08-02 : BRAIN MRI + MRA [Finding] PVWM UBO underlying SVD . Left thalamus occipital lobe patchy high signalintensity FLAIR image . T1WI iso signal intensity portion Radiology ResultsInverted FileSignificant words onlyIndexing with Inverted File
WORDDPWabort1,5aberrant 3brain7,3portion4,8topology5,8
Evaluation of IRRecall ( ) Precision
Word based indexing Contextmeaning is affected by meaning of other wordshigh, blood, pressurelow pressure at high altitude increase red blood cellPolysemylead vs leadSynonymyhypertension vs. high blood pressureGranularityantibiotics, penicillinFocus of ContentKey word vs Plain word
The End