近年來由於網路技術不斷地進步及網路頻寬大幅地增加，過去只能提供簡單的文字及聲音的網路媒體，如今進化為能提供圖片及多媒體影片的網路媒體。例如:由中華電信公司推出的互動式多媒體隨選視訊服務(MOD)就是一個最典型的例子。由於網路使用人口呈現越來越多的趨勢，且網路的應用也越來越往多媒體影片服務方面來發展。有鑑於此，本論文將利用資料探勘的概念，配合預存式機制的技術來解決在視訊系統中的影片快取機制問題。配合該機制，我們能提供一個簡單的小型配送系統，來解決目前在多媒體配送系統中，提高快取伺服器的命中率減少點選影片的反應時間及大量的人力資源浪費還有避免人為疏失上的可能。
本論文的核心在探討在視訊系統(如VOD、MOD系統)環境下快取機制的資料探勘(data mining)議題。由於視訊系統都有網路頻寬的限制問題，所以將欲觀賞的影片資料先存放於當地的視訊伺服器主機內，來提升用戶連線的反應時間效率及減少核心網路流量是有必要的。我們利用資料探勘的技術，從媒體中心的影片資料庫中找出一般使用者可能欲觀看的影片，預先將要觀賞的影片存入當地的視訊伺服器(或稱快取伺服器)的儲存空間內，使得使用者觀看影片的反應時間有大幅度的改善。
本論文第四章以模擬方式對本研究提出系統架構作效能評估，發現影片命中率有顯著改善，進而改善整體視訊系統的效能。本論文提出的PSM機制與LFU、LRU演算法相比較，在命中率上有明顯的提升。在快取空間佔影片資料庫比重為三成時，比LFU及LRU的快取命中率平均提升26.6%。
本論文研究建立視訊系統中TVOD的快取機制，讓使用者可以更有效率的在TVOD系統中觀看影片。藉此提供未來TVOD系統設計者更完善的考量，作為日後發展出更完美的TVOD視訊系統管理機制的參考。

Recently, by reason of progressing of the internet technology and high-speed network bandwith, it will come true to provide services of video-on-demand on internet. Now, Internet not only provides text and picture medias but also videoes.For a typical example, Chunghwa Telecom‘s MOD service. Because more people using internet than before, application of internet begins toward multimedia services field. Because of this, we use the technology of data mining and PreStore Mechanism (PSM) to help solving cache problem in VOD (video-on-demand) system.Using PSM, we can provide a simple and small video delivery system. It can help us reducing response time of waiting and plenty of human resources. Finally, it can also help us avoiding human fault on VOD delivery system.
This thesis discusses the issue of cache mechanism of VOD/MOD system. Because the limit of internet bandwith, it is always necessary for VOD system putting hot moive on local video server/cache video server. In this case, VOD system will have good reponse time and reducing instant flush of network flow.We use data mining method to find out hot movies which general users maybe want to see. We also use data mining skill to prestore hot movies in local video server/cache video server. That did work for reponse time of waiting to seeing movies.
The chapter 4 of this thesis provides simulation methods to analysis performance of VOD system.We find reponse time and performance of VOD system having massive progress. We also compare our PSM to LFU and LRU. We find the results of PSM’s hit rate better than LFU and LRU. The improvement on LRU and LFU for hit ratio is 26.6% averagely.
The study establishes the cache mechanism in TVOD environment. Users can query the movie more efficiently on the TVOD system. It provides the TVOD system makers with a more perfect decision environment and services as a further reference for the development of an advanced management mechanism of TVOD system.

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