Development of Advanced Web Data Houses and its Application to Education Systems

利用网络的教育系统已经引起了人们的注意。随着教育内容和学生数量的增加，数据的处理效率成为一个问题。我们一直在为高效的网络信息处理而提出和开发网络仓库。在本研究中，我们从教育应用的角度设计了网络仓库，并为开发网络仓库和应用系统所需的功能进行了一系列的研究，主要内容如下：环境教育的网络内容：为了支持野外环境教育，我们开发了一个系统，收集各种观测数据，如文本、数码相机图像和GPS获取的位置信息，并将它们组装成网络内容。基于操作历史的网络自主学习系统的教师辅助机制：我们开发了一个基于操作历史的网络自主学习系统，该系统采用…更多的学生通过网络界面提问和记录答案，并在高中补习班中应用了该系统。该系统的特点是记录学生在PC机上的所有操作，这些记录可以从答题顺序、答题时间、学生引用的提示、答案的正确性等不同角度进行分析。Web仓库的访问控制：Web仓库随着时间的推移积累了大量的数据，需要为Web仓库上的数据建立访问控制模型，其中需要融入Web仓库的版本派生、内容结构和时间戳等语义。我们开发了一个符合这些要求的新模型，并给出了评估算法。Web服务器的异常检测：Web服务器因接管或破坏服务器而受到未知攻击者的严重攻击，这是一个严重的问题。我们开发了一个系统，利用数据挖掘方法将网络访问日志可视化，以检测可疑活动。较少

Education systems utilizing the Web have been attracting attentions. By the increase of the volume of education contents and students, the efficiency of processing data becomes a problem. We have been proposing and developing web warehouses for efficient web information processing. In this research, we designed web warehouses from the point of views of education applications, and conducted a series of researches for developing necessary functionalities for the web warehouse and application systems, as summarized below :Web-base contents for environment education : For supporting environment education in field situations, we developed a system to collect various observation data, such as text, images from digital cameras and location information obtained by GPS, and assembles them into web contents. The system was demonstrated in EXPO2005.Teacher-assistance mechanism for web-based self-learning system utilizing operation histories : We developed a web-based self-learning system, which p … More resents questions and records answers through web interface, and we applied the system in high-school supplementary classes. The system's feature is a recoding mechanism which records all the operations by students on PCs, and these records can be analyzed from various point of views, such as answering orders, answering time, hints referred by students, correctness of answers. Through the visualization of record analysis, teachers can evaluate performance of students.Access control of web warehouses : A web warehouse accumulates huge data as the time passes, and it is necessary to build an access control model for the data on web warehouses, where semantics of web warehouses, such as version derivation, content structure, and timestamps, need to be incorporated. We developed a new model which fits these requirements, and we also showed evaluation algorithms.Detecting anomalies of web servers : It is becoming a serious problem that web servers are heavily attacked by unknown adversaries for taking over or sabotaging the server. We have developed a system to visualize web access logs for detecting suspicious activities, utilizing data mining methodologies. Less