在過去的程式碼搜尋研究中，大多利用傳統TFIDF公式來計算詞彙權重，然而程式碼與一般文件不同，程式碼擁有高度的結構性。本研究是利用過去在資訊檢索(Information Retrieval)領域中，最常被使用的查詢擴展(Query Expansion)技術及其假定相關回饋(Blind Feedback)技術為研究基礎，以統一建模語言(Unified Modeling Language, UML)觀點來改良BM25(Best Match 25)公式，並結合動態擴展詞演算法，發展出可應用於程式碼搜尋的查詢擴展技術。
本研究達到的貢獻有以下四點：(1) 運用查詢擴展技術於程式碼搜尋，以解決「概念性查詢詞搜尋偏差」的問題。(2) 依UML類別圖觀點定義程式碼中類別間的關係，提出改良式BM25演算法，利用該方式可運用在任何物件導向程式語言。(3) 依檢索系統評估中F-measure定義，提出動態擴展詞演算法，利用該方法，可依不同查詢詞動態找出須加入的擴展詞數量。(4) 透過本研究所發展的程式碼搜尋系統，可符合新進程式開發者的思考模式，有效提升系統開發效率。
最後經本研究實驗結果證明，本系統可將查準率由原來的30%左右，提升到88%左右，藉此證實本研究所提出的方法確實可讓新進程式開發者更容易找到相關的程式碼。

The code searches in past studies, we used traditional TFIDF formula to calculate the weights of term and general documents. However, it is different with word documents, the code is more high-level structural.Query Expansion and Blind Feedback technology are the most commonly used in the domain of information retrieval. Based on UML (Unified Modeling Language) perspective, we adopt Query Expansion and Blind Feedback technology to improve the formula of BM25 (Best Match 25). In the mean time, we combine them with Dynamic Expansion Term Algorithm to develop query expansion in searching codes.
In this study, our contributions are the followings:(1) Using Query Expansion in searching codes, we can improve the searching bias of conceptual query.(2) UML class diagram in accordance with the definition of the code point of view the relationship between classes, we improve the formula of BM25 and apply it to object-oriented programming language.(3) Depending on the definition of retrieval system in F-measure, we develop Dynamic Expansion Term Algorithm to find out more accuracy expansion term immediately in any query words.(4) In our code searching system, we can help the beginners in programming and improve the work efficiency.
According to the final results of this study, it shows that this system can raise the precision rate from 30% to 88%. And it shows that our method does help the beginners in programming and find out the code in detail.

中文部份
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網頁資料
34. Codase Source Code Search Engine．2010年5月30日取自http://www.codase.com/
35. Google Code Search Engine．2010年5月30日取自http://www.google.com/codesearch/
36. JDT plug-in developer guide．2010年5月30日取自http://help.eclipse.org/ganymede/index.jsp?topic=/org.eclipse.jdt.doc.isv/reference/api/org/eclipse/jdt/core/dom/package-summary.html
37. Koders source code search engine．2010年5月30日取自http://www.koders.com/
38. Krugle source code search engine．2010年5月30日取自http://www.krugle.org/
39. Object management group: Unified modeling language．2010年5月30日取自http://www.uml.org/
40. SourceForge.net. Open source software．2010年5月30日取自http://sourceforge.net/