Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Ontology Based Qualitative Information Collection(Izmir Institute of Technology, 2014) Kaysı, Ezgi; Aytaç, İsmail SıtkıThe World Wide Web is an information resource with essentially limitless potential. However, this potential is relatively untapped because it is tough for machines to process and integrate this information meaningfully. Recently, researchers have started to explore to combine web content with specified meaning, in order to create a Semantic Web. It is one of the most encouraging and rising areas of computer science. Its capabilities to make information that is understandable to be understood and processed by machines and humans. Semantic Web approach will strictly change the effectiveness of the Internet and will enable the reuse of information and increase the representative power of information. It will be possible to combine information from different locations and process them together since they are defined in a standard way. The potential of the Semantic Web is demonstrated with “Semantic Hotel Search” application. Also basic concepts referring knowledge with a Semantic Web language, ontology processing, reasoning and querying on ontologies are presented. Semantic Hotel Search application that contains a dynamic knowledge base holding hotel related information, which is updated at every day from the information provided in the hotels‟ websites. All the information and application logic have been moved into an OWL file which controls all the content and the structure of the application. In addition to, sentimental analysis is associated with this application. Therefore, users can see what the other people said about hotels and whether user has positive or negative comment in order to make better decision. Both travelers and travel service providers can benefit from the implemented semantic web based application. Semantic Web based travel portal can reduce search costs and a case study shows that the system provides time efficiency and is helpful in decision making.Master Thesis Trajectory Prediction of Moving Objects by Means of Neural Networks(Izmir Institute of Technology, 1997) Barışık, Hakan; Aytaç, İsmail Sıtkı; Aytaç, İsmail SıtkıEstimating the three-dimensional motion of an object from a sequence of object positions and orientation is of significant importance in variety of applications in control and robotics. For instance, autonomous navigation, manipulation, servo, tracking, planning and surveillance needs prediction of motion parameters. Although "motion estimation" is an old problem (the formulations date back to the beginning of the century), only recently scientists have provided with the tools from nonlinear system estimation theory to solve this problem eural Networks are the ones which have recently been used in many nonlinear dynamic system parameter estimation context. The approximating ability of the neural network is used to identifY the relation between system variables and parameters of a dynamic system. The position, velocity and acceleration of the object are estimated by several neural networks using the II most recent measurements of the object coordinates as input to the system Several neural network topologies with different configurations are introduced and utilized in the solution of the problem. Training schemes for each configuration are given in detail. Simulation results for prediction of motion having different characteristics via different architectures with alternative configurations are presented comparatively.Master Thesis Intrusion Detection System Alert Correlation With Operating System Level Logs(Izmir Institute of Technology, 2009) Toprak, Mustafa; Aytaç, İsmail SıtkıInternet is a global public network. More and more people are getting connected to the Internet every day to take advantage of the Internetwork connectivity. It also brings in a lot of risk on the Internet because there are both harmless and harmful users on the Internet. While an organization makes its information system available to harmless Internet users, at the same time the information is available to the malicious users as well. Most organizations deploy firewalls to protect their private network from the public network. But, no network can be hundred percent secured. This is because; the connectivity requires some kind of access to be granted on the internal systems to Internet users. The firewall provides security by allowing only specific services through it. The firewall implements defined rules to each packet reaching to its network interface. The IDS complements the firewall security by detected if someone tries to break in through the firewall or manages to break in the firewall security and tried to have access on any system in the trusted site and alerted the system administrator in case there is a breach in security. However, at present, IDSs suffer from several limitations. To address these limitations and learn network security threats, it is necessary to perform alert correlation. Alert correlation focuses on discovering various relationships between individual alerts. Intrusion alert correlation techniques correlate alerts into meaningful groups or attack scenarios for ease to understand by human analysts. In order to be sure about the alert correlation working properly, this thesis proposed to use attack scenarios by correlating alerts on the basis of prerequisites and consequences of intrusions. The architecture of the experimental environment based on the prerequisites and consequences of different types of attacks, the proposed approach correlates alerts by matching the consequence of some previous alerts and the prerequisite of some later ones with OS-level logs. As a result, the accuracy of the proposed method and its advantage demonstrated to focus on building IDS alert correlation with OS-level logs in information security systems.Master Thesis Reconstruction of X-Ray Images(Izmir Institute of Technology, 1997) Aka, Hüseyin Cüneyt; Aytaç, İsmail SıtkıWe have presented an integrated approach in retrieving, reconstructing, and storing images obtained from noisy X-rays in this study. The X-ray images are used to detect human body's invisible parts. The problem of blurring and uneven illumination is always faced. Although it is partially solved by the physicians via lighting the X-rays, this method is not working properly in some cases such as Vesico Ureteral Reflux disease. This may cause loss of some meaningful part of the information and failure in diagnosis process. In order to decrease such errors, some computational methods has been developed by means of image processing. Due to its very nature, reconstruction, retrieving and registration of x-ray images has been chosen as a subject of this study. We have begun attacking the problem of reconstruction and extraction, then started to generate multi-layer hierarchical solutions. We have tried so many different approaches for each layer in our experiments. In each experiment, some methods produced accurate results, some methods did not. Thus, we have exerted every effort to optimize the solution for each layer. Although we have worked with limited number of sample images,(due to the problem of retrieving x-rays which is seen in this case) the results show us that, all the samples that we have processed, could have been reconstructed and stored as we have expected.Storing of the huge amount of data is an another problem in our area of interest, because of image characteristics. Every kidney image consists of nearly 120.000 (around 300x400) pixels. However, in our case, the boundaries of kidney region are sufficient for diagnosis. In other words, storing the boundaries instead of complete image has the same precision. We detected and stored the kidney's boundary coordinates on both x and y axis. Although this was sufficient for our study, we have decided to develop a much more flexible file format by ordering x and y coordinate couples in counter clockwise direction with the same information for further studies such as computer aided diagnosis systems.Master Thesis Craniofacial Computer Assisted Surgical Planning and Simulation(Izmir Institute of Technology, 1999) Ekin, Emine; Aytaç, İsmail SıtkıIn this work, mainly, the first step of craniofacial surgical simulation and planning procedure, reconstruction of tomography images is investigated. The Direct Reconstruction techniques and algebraic methods are described in detailed mathematical formulations for both two and three-dimensional cases. And also a brief description of medical imaging techniques and the terminology of craniofacial surgical simulation and planning is given. In the last chapter the implementation details, the algorithms developed and some resulting images are given and the images are compared with respect to the used algorithms.Master Thesis Empirical Computation of Absorbed Radiation in Medium Like Human Body and Graphical Representation of Dose Distribution(Izmir Institute of Technology, 2001) Gökçe, Tuncay Cemil; Aytaç, İsmail Sıtkı; Aytaç, İsmail SıtkıComputers, in radiotherapy, are now widely used for calculating and displaying dose distributions for optimum therapy planning. There are lots of hardware options and commercial programs, which were developed outside Turkey, available in the market. In this study, we propose a system, which can be used with a conventional PCs running with Windows NT operating system. Our first clinical tests show that this system is very efficient and suitable for clinical requirements. Also in future developments of the software is very easy.Master Thesis Time synchronization in wireless sensor metworks(Izmir Institute of Technology, 2008) Kulaklı, Ali Burak; Aytaç, İsmail SıtkıIn this thesis, an enhanced synchronization algorithm for Wireless Sensor Networks is proposed. This algorithm uses TPSN (Timing-sync protocol for sensor networks) as a base synchronizer and does modifications on it to achieve a better synchronization with a lower message overhead. Basically, there are three improvements that can be applied onto TPSN, which are clustering the network, chain synchronization among nodes and adaptive synchronization interval. In the first phase of the thesis, a simulation environment is provided for TPSN using pthreads on a Linux computer. This environment helps understanding the parameters that TPSN relies on and testing the algorithm in different simulated environments with different characteristics using the enhancements onto TPSN algorithm. In the second phase, ns2 simulator environment is used to get more precise results and test the modifications. Finally, latest modifications are done on TPSN and all the results are gathered from ns2.Master Thesis Web Based User Accounting System for Internet Service Providers(Izmir Institute of Technology, 1999) Balcı, Murat; Aytaç, İsmail SıtkıThere are some basic operations, that any Internet Service Provider (ISP) must do, such as adding, removing users, disabling and enabling users, changing user passwords etc. Beside these basic operations, all ISPs must design a accounting system to bill the users. Most of the currently available ISP packages run on Windows NT or UNIX systems and in client side a specific client program is developed, which runs only on specific operating system (OS) (say Windows NT). If ISP want to access these ISP operations from an another OS (say from UNIX (with hundreds of its derivatives), OS/2, MacOS etc.), client program must be ported to each of the OS. Although this is possible in theory, in practice it is very difficult and not cost effective.In this thesis to solve this problem, a Web based user accounting system IS proposed. In a Web based system anyone who has a regular Web browser can access the ISP data, manage and view them (ofcourse securely) no-matter where he is in the world which OS he uses. This approach makes ISP accounting easy and cost effective. Additionally making the system in Turkish, increases the useability of the system for the Turkish users.Master Thesis An Education Environment for Web Based Training(Izmir Institute of Technology, 2001) Kılınç, Hacı Hakan; Aytaç, İsmail SıtkıThe purpose of this thesis is to prepare of an interactive education environment and to represent to the available courses in Izmir Institute of Technology, on the Web and to contribute to the studies about distance education in our country. An interactive education environment, which is called the Virtual Campus, had been created using internet technologies such as ASP, VBScript, JavaScript and HTML. The Virtual Campus is an independent education environment of time and location.Master Thesis An Operating System for Data Acquisition and Control Applications(Izmir Institute of Technology, 1999) Ayav, Tolga; Aytaç, İsmail SıtkıThe common controllers used in industrial environments today cannot fulfill the requirements of many data acquisition and control applications. As a result of this, personal computers has become to be popular in industry, as they have been so in many areas due to the fact that today's PCs have many advantages compared with their relatively low price. In this project, a PC based embedded controller was designed for data acquisition and control purposes, and a real-time executive running on DOS operating system was developed.
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