Master Tezleri

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Access monitoring system for distributed firewall policies
(Izmir Institute of Technology, 2008) Çakı, Oğuzhan; Tuğlular, Tuğkan; Tuğlular, Tuğkan
Internet has provided several benefits in terms of information sharing. However, Internet is an insecure environment that can cause threats to private networks. As a result, network security becomes a critical issue. One of the important tools used in network security is firewall. Firewalls protect a private network from external threats by restricting network traffic according to predefined security rules. Basically, firewalls apply these rules to each packet that passes over them. Distributed firewalls are a new approach to firewall to overcome some drawbacks of traditional firewalls. Distributed firewall design is based on the idea of enforcing the policy rules at the endpoints rather than a single entry point to network. Management of policy rules is a critical issue in both traditional and distributed firewalls. We propose a monitoring application for distributed firewall policies to keep track of actions (create, read. update, delete) performed on policy rule set. The resulting data produced by the monitoring application will be very helpful in policy management process.
Adaptive thermal comfort analysis of historic mosque: The case study of Salepçioğlu Mosque, Izmir, Turkey
(Izmir Institute of Technology, 2016-10) Bughrara, Khaled S. M.; Durmuş Arsan, Zeynep; Gökçen Akkurt, Gülden
Mosques differ from other types of buildings by having intermittent operation schedule. Due to five prayer times per day throughout the year, mosques are fully or partially, yet periodically, occupied. Historic mosques, possessing cultural heritage value, need to be evaluated in terms of thermal comfort. The adaptive thermal comfort method presented by ASHRAE 55 is recommended to be used to analyze thermal comfort conditions of unconditioned buildings. The aim of research is to analyze thermal comfort conditions of historic mosques throughout the year, and to conduct an adaptive comfort analysis. The selected Salepçioğlu Mosque was built in 1905 in Kemeraltı, İzmir, Turkey. The objective is to improve indoor thermal comfort levels by applicable interventions with specific attention to its heritage value. First, indoor and outdoor microclimate of Salepçioğlu Mosque was monitored from October 2014 to September 2015. The physical model of mosque was created via dynamic simulation modelling tool, DesignBuilder v4.2. The model was calibrated by comparing simulated and measured indoor air temperature within hourly error ranges defined by ASHRAE Guideline 14. Whole-year thermal comfort analysis was conducted on monthly basis by using adaptive thermal comfort model. The adaptive comfort analysis of monitoring campaign shows that the Mosque does not satisfy acceptable comfort levels. Different scenarios were applied to better comfort levels. The best improvement is obtained with underfloor heating by which discomfort hours drop into 1369 hours by 31.34%, while it was 3760 hours by 86.08% in the baseline model.
Analysis of feature pattern mining approaches on social network: A case study on Facebook
(Izmir Institute of Technology, 2017-12) Öztürk, Elif; Şahin, Serap
Pattern mining algorithms obtain patterns frequently seen in a database and complex graphs which are available from gene networks to social networks. Complex graphs contain lots of valuable information on their nodes or edges. For this reason, pattern mining algorithms can be used to extract data from complex networks. However, these algorithms usually work on the graphs whose nodes have a single label. If these algorithms are implemented on multi labeled (multi-attributed) complex graphs, their complexities belong to NP-Complete. For this reason, in this study, different approaches have been evaluated to find patterns. The goal is to understand related methods and algorithms with their pros and cons to obtain common feature patterns from multi-attributed complex graphs. We also selected Facebook social network complex graph data set (SNAP - Stanford University FaceBook anonymized data set) as an application domain and we analyzed the most frequent feature patterns on friendship relations.
An analysis of information spreading and privacy issues on social networks
(Izmir Institute of Technology, 2017-12) Sayin, Burcu; Şahin, Serap
With Social Networks (SNs), being populated by a still increasing number of people, who take advantage of the communication and collaboration capabilities that they offer, density of the information, spread over SNs is increasing steadily. Furthermore, the probability of exposure of someone’s personal moments to a wider than expected crowd is also increasing. Hence, analyzing the spreading area and privacy level of any information through a SN is an important issue in social network analysis. By studying the functionalities and characteristics that modern SNs offer, along with the people’s habits and common behavior in them, it is easy to understand that several privacy risks may exist, for many of which people may be unaware of. We address this issue, focusing on interactions with posts in a SN, using Facebook as the research domain. As a novelty, we propose an application tool which visualizes the effect of potential privacy risks in Facebook and provides users to control their privacy. The proposed (and simulated) tool allows a Post Owner to observe the spreading area of his/her post, depending on the selected privacy settings of this post. Moreover, it provides preliminary feedback for all the Facebook users that have interacted with this post, to make them aware of the possible privacy changes, aiming to give them a chance to protect the privacy of their interaction on this post by deleting it when such a privacy change takes place.
Analysis of intrusion prevention methods
(Izmir Institute of Technology, 2004) Semerci, Hakan; Tuğlular, Tuğkan; Tuğlular, Tuğkan
Today, the pace of the technological development and improvements has compelled the development of new and more complex applications. The obligatory of application development in a short time to rapidly changing requirements causes skipping of some stages, mostly the testing stage, in the software development cycle thus, leads to the production of applications with defects. These defects are, later, discovered by intruders to be used to penetrate into computer systems. Current security technologies, such as firewalls, intrusion detection systems, honeypots, network-based antivirus systems, are insufficient to protect systems against those, continuously increasing and rapid-spreading attacks. Intrusion Prevention System (IPS) is a new technology developed to block today.s application-specific, data-driven attacks that spread in the speed of communication. IPS is the evolved and integrated state of the existing technologies; it is not a new approach to network security. In this thesis, IPS products of various computer security appliance developer companies have been analyzed in details. At the end of these analyses, the requirements of network-based IPSs have been identified and an architecture that fits those requirements has been proposed. Also, a sample network-based IPS has been developed by modifying the open source application Snort.
An analysis of key generation efficiency of RSA cryptosystem in distributed environments
(Izmir Institute of Technology, 2005) Çağrıcı, Gökhan; Koltuksuz, Ahmet Hasan
As the size of the communication through networks and especially through Internet grew, there became a huge need for securing these connections. The symmetric and asymmetric cryptosystems formed a good complementary approach for providing this security. While the asymmetric cryptosystems were a perfect solution for the distribution of the keys used by the communicating parties, they were very slow for the actual encryption and decryption of the data flowing between them. Therefore, the symmetric cryptosystems perfectly filled this space and were used for the encryption and decryption process once the session keys had been exchanged securely. Parallelism is a hot research topic area in many different fields and being used to deal with problems whose solutions take a considerable amount of time. Cryptography is no exception and, computer scientists have discovered that parallelism could certainly be used for making the algorithms for asymmetric cryptosystems go faster and the experimental results have shown a good promise so far. This thesis is based on the parallelization of a famous public-key algorithm, namely RSA.
Anomaly detection using network traffic characterization
(Izmir Institute of Technology, 2009) Yarımtepe, Oğuz; Tuğlular, Tuğkan; Tuğlular, Tuğkan
Detecting suspicious traffic and anomaly sources are a general tendency about approaching the traffic analyzing. Since the necessity of detecting anomalies, different approaches are developed with their software candidates. Either event based or signature based anomaly detection mechanism can be applied to analyze network traffic. Signature based approaches require the detected signatures of the past anomalies though event based approaches propose a more flexible approach that is defining application level abnormal anomalies is possible. Both approach focus on the implementing and defining abnormal traffic. The problem about anomaly is that there is not a common definition of anomaly for all protocols or malicious attacks. In this thesis it is aimed to define the non-malicious traffic and extract it, so that the rest is marked as suspicious traffic for further traffic. To achieve this approach, a method and its software application to identify IP sessions, based on statistical metrics of the packet flows are presented. An adaptive network flow knowledge-base is derived. The knowledge-base is constructed using calculated flows attributes. A method to define known traffic is displayed by using the derived flow attributes. By using the attributes, analyzed flow is categorized as a known application level protocol. It is also explained a mathematical model to analyze the undefined traffic to display network traffic anomalies. The mathematical model is based on principle component analysis which is applied on the origindestination pair flows. By using metric based traffic characterization and principle component analysis it is observed that network traffic can be analyzed and some anomalies can be detected.
Application development for improving website usability by web mining methods
(Izmir Institute of Technology, 2018-06) Tüker, Merve Ceren; Bostanoğlu, Belgin Ergenç
The explosive growth in website traffics and website usage data has resulted in the amount of valuable information contained to have a similar uptrend in web usage logs. With the increasing competition between websites, mining web usage logs to discover meaningful information is needed more than ever. Web usage mining is the procedure of using data mining methods to discover insightful patterns in web usage logs. The discovered information helps understand how users behave on the website and their needs. One of the most popular algorithmic approaches of pattern mining on web usage data is the Fp-growth algorithm. For larger volumes of data, the algorithm is generally applied to execute in parallel. Measuring and comparing performances of applications is difficult, because the algorithm performs different on usage logs with different characteristics. The characteristics of usage logs are highly related with the type of the website. In this paper, we have investigated how different characteristics of web usage logs effect the performance of the parallel Fp-growth algorithm. Five datasets with varying log characteristics were used in order to represent different business models. The results suggest that the performance is highly correlated with the number of items, number of frequent items, transaction length, similarity between frequent patterns, minimum support value and size of the log file.
Application of graph neural networks on software modeling
(01. Izmir Institute of Technology, 2020-12) Leblebici, Onur Yusuf; Tuğlular, Tuğkan; Tuğlular, Tuğkan; Belli, Fevzi; 01. Izmir Institute of Technology
Deficiencies and inconsistencies introduced during the modeling of software systems can cause undesirable consequences that may result in high costs and negatively affect the quality of all developments made using these models. Therefore, creating better models will help the software engineers to build better software systems that meet expectations. One of the software modelling methods used for analysis of graphical user interfaces is Event Sequence Graphs (ESG). The goal of this thesis is to propose a method that predicts missing or forgotten links between events defined in an ESG via Graph Neural Networks (GNN). A five-step process consisting of the following steps is proposed: (i) data collection from ESG model, (ii) dataset transformation, (iii) GNN model training, (iv) validation of trained model and (v) testing the model on unseen data. Three performance metrics, namely cross entropy loss, area under curve and accuracy, were used to measure the performance of the GNN models. Examining the results of the experiments performed on different datasets and different variations of GNN, shows that even with relatively small datasets prepared from ESG models, predicts missing or forgotten links between events defined in an ESG can be achieved.
Application of zeolites in biotechnology: Protein adsorption
(Izmir Institute of Technology, 1998) Özgü, Şebnem Karasu; Ülkü, Semra
Recovery of proteins from vanous culture broths is a complex engmeenng problem, involving multi-step schemes that lead to significant loss of the desired bioproduct by conventional methods. The bioproduct is not only present in very low concentrations, but also it is subject to chemical/enzymatic degradation. An alternative cost-effective method for recovery of proteins in a highly purified form may be through adsorption, which is a separation technique based on specific and reversible binding, with the use of zeolites that have favorable adsorption characteristics over the other adsorbents. Protein adsorption characteristics of a natural zeolite (clinoptilolite from Turkey) and a synthetic (3A) zeolite were determined through various experiments, altering parameters as pH (range 3.5-6), the amount of zeolites used for adsorption (0.01-0.05 g/ml) and the initial protein concentration (0.01-0.1%). Within the concentration and pH ranges studied, the adsorption capacity of the zeolites was around 50 mg protein/g zeolite. For natural zeolite, approximately 98% was adsorbed within the first 2 minutes, while for the synthetic zeolite, 70% was adsorbed within the first 15 minutes. Uptake diagrams were obtained, adsorption isotherms were determined and Langmuir method was used to describe the isotherms. Desorption was also investigated after treating the zeolites with salt and acid, but further work is necessary for obtaining better recovery. It can be concluded that clinoptilolite is capable of adsorbing proteins in a short time. This study may be the preliminary step, followed by further laboratory work and necessary scale-up experiments, towards the use of zeolites in the recovery of proteins in industry as an alternative to conventional methods.
Assessment and certification of safety critical software
(Izmir Institute of Technology, 2018-07) Uzun Yenigün, Bengisu; Ayav, Tolga; Ayav, Tolga
Biomedical engineering which consists of combination of various dicipline such as chemical, biology etc. produces remedies to the challenges facing the globalizing world. Therefore, it covers a wide range of area from biosensor to surgical robots. Rapid development of biomedical engineering technology is aimed to research, diagnose and treatment to modern society for providing improved living conditions. Safety critical systems are interested with systems whose failure or malfunction could cause death, serious injury, damage to equipment and environmental harm. NeuRoboScope project is a safety-critical system which navigates the optical-camera system used in the endoscopic pituitary surgery by tracking the surgery tool that the surgeon uses. This thesis gives the information of how we scrutinize NeuRoboScope project depending on standards of medical device which are ISO 14971, IEC 62304, IEC 60601 and DO-178C.
Asymmetric membrane tablet coatings for controlled-release of drugs
(Izmir Institute of Technology, 2002) Yenal, Hacer; Alsoy Altınkaya, Sacide
Most of the controlled release systems developed for drug delivery applications dependon membrane technology. The dense structure of the membrane in conventional controlled release systems prolongs the release of drug. To eliminate this disadvantage while maintaining the benefits of dense membrane systems, an asymmetric type of coating was applied on tablets. Coatings were prepared from cellulose acetate, acetone, water solution by phase inversion technique. To determine the release rate of drug, dissolution studies on tablets were performed according to United States of Pharmacopeia (USP). In these studies, the effects of composition of the polymer/solvent/nonsolvent, coating time, number of coating layers, evaporation conditions and the nonsolvent type on the release rate of the drug and the structure of membrane were investigated. Experiments were designed using commercial software package Design-Expert and a quadratic model equation was obtained to predict the effect of composition of cellulose acetate, acetone and water on the release rate of drug. The advantage of asymmetric type coating over the conventional dense type coating was further demonstrated by measuring the permeabilities of both type of coatings. In addition, the structures of membranes were analyzed using scanning electron microscope (SEM) micrographs.
Automatic matching of aerial coastline images with map data
(Izmir Institute of Technology, 2005) Kahraman, Metin; Gümüştekin, Şevket
Matching aerial images with map data is an important task in remote sensing applications such as georeferencing, cartography and autonomous navigation of aerial vehicles. The most distinctive image features that can be used to accomplish this task are due to the unique structures of different coastline segments. In recent years several studies are conducted for detecting coastlines and matching them to map data. The results reported by these studies are far from being a complete solution, having weak points such as poor noise sensitivity, need for user interaction, dependence to a fixed scale and orientation.In this thesis, a two-step procedure involving automatic multiresolution coastline extraction and coastline matching using dynamic programming have been proposed. In the proposed coastline extraction method, sea and land textures are segmented by using cooccurrence and histogram features of the wavelet image representation. The coastlines are identified as the boundaries of the sea regions. For the coastline matching, shape descriptors are investigated and a shape matching method using dynamic programming is adapted. Proposed automatic coastline extraction and coastline matching methods are tested using a vector map of the Aegean coast of Turkey.
Automatic question generation using natural language processing techniques
(Izmir Institute of Technology, 2018-07) Keklik, Onur; Tuğlular, Tuğkan; Tuğlular, Tuğkan; Tekir, Selma
This thesis proposes a new rule based approach to automatic question generation. The proposed approach focuses on analysis of both syntactic and semantic structure of a sentence. The design and implementation of the proposed approach are also explained in detail. Although the primary objective of the designed system is question generation from sentences, automatic evaluation results shows that, it also achieves great performance on reading comprehension datasets, which focus on question generation from paragraphs. With respect to human evaluations, the designed system significantly outperforms all other systems and generated the most natural (human-like) questions.
Automatic quote detection from literary work
(01. Izmir Institute of Technology, 2022-12) Güzel Altıntaş, Aybüke; Tekir, Selma
Literature inspires readers, and readers tend to share quotes from a literary work. The reader underlines the quotes in the book and shares them on social media, or on an online platform used by book readers. The definition of a quote is a span in a written text that is interesting for many readers and readers can use the quote in different contexts. In this study, a novel task in the field of Natural Language Processing is proposed: the Quote Detection Task. Also, an original dataset was formed from the Goodreads and Gutenberg websites with web scraping. Quotes are Goodreads data sourced from Kaggle and data that has been voted by 10 or more users are selected. These quotes have been validated with the books on the Project Gutenberg website. The final dataset consists of 4554 rows. The dataset contains quotes with their book spans. The span of a quote consists of the previous 10 sentences of the quote, the quote itself, and the following 10 sentences of the quote. Conditional Random Field (CRF) and Extractive Summarization as Text Matching (MatchSum) were run as two different baselines for quote detection. The Quote Detection Task is span detection that can be modeled with sequence labeling solutions and Neural extractive summarization systems in the literature. For this sequence tagging problem, the statistics-based CRF was run as first baseline. Extractive Summarization as Text Matching baseline is the second baseline chosen for the experimental part. Rouge-1 scores of 27.24% and 40.54%, respectively, were obtained from these baselines.
An automatic vision guided position controller in a conveyor belt pick and place system
(Izmir Institute of Technology, 2006) Çelikdemir, Özgür; Aytaç, İsmail Sıtkı
An automatic vision guided position controller system is developed as for possible applications such as handling and packaging that require position and orientation control. The aim here is to minimize the production cycle time, and to improve the economic performance and system productivity. The system designed can be partitioned into five major parts: vision module, pneumatic automation module, manipulator, conveyor-belt and a software that manages and integrates these modules. The developed software captures raw image data from a camera that is connected to a PC via usb port. Using image processing methods, this software determines the proper coordinates and pose of the moving parts on the conveyor belt in real time. The pick and place system locates the parts to the packaging area as part.s predefined orientation. The software communicates with a controller card via serial port, manages and synchronizes the peripherals (conveyor belt stepper motors- pneumatic valves,etc) of the system. C programming language is used in the implementation. OpenCV library is utilized for image acquisition. The system has the following characteristics: The Conveyor belt runs with a constant speed and objects on the conveyor belt may have arbitrary position and orientation. The vision system detects parts with their position and orientation on the moving conveyor belt based on a reference position. The manipulator picks the part and then corrects its position comparing the information obtained by vision system with predefined position, and it places the object to the packaging area. System can be trained for the desired position of the object .
Basic key exchange protocols for secret key cryptosystems under CRYMPIX library
(Izmir Institute of Technology, 2007) Uslu, Sevgi; Koltuksuz, Ahmet Hasan
Key exchange protocols are developed in order to overcome the key distribution problem of symmetrical cryptosystems. These protocols which are based on various algebraic domains are different implementations of public-key cryptography. In this thesis, the basic key exchange protocols are reviewed and CRYMPIX implementations of them are provided. CRYMPIX has a portable structure that provides platform independence for generated code. Hence, the implemented key exchange mechanisms are suitable to be used on different hardware and software platforms.
A basic web-based distance education model
(Izmir Institute of Technology, 2005) Turanlı, Dehan; Aytaç, İsmail Sıtkı
During the recent years, the rapid growth of the Web and multimedia technologies urged a shift of Computer-Based Educational Technology towards the Web. In the leading universities of the developed countries, studies on Web-Based Education have started and in an increasing manner are going strong. In the last few years, the leading universities of Turkey are also greatly interested in Web-Based Education and have started their re-structuring accordingly.The goal of this study is to design a basic model to be utilized by a university aiming to offer web-based distance education. In achieving this; by the use of system approach, a model comprising of three subsystems, namely system analysis, system design and evaluation&control, working in coordination with each other, has been tried to be proposed. There may be only one missing point of this study, that is; since preparing a lesson or program according to this model was not foreseen in this thesis, the effectiveness evaluations suggested in the evaluation&control subsystem could not be realized. It is recommended to realize such an evaluation in a further study to make it possible to reveal the effectiveness of web-based education by preparing a lesson or program according to this model.On the other hand, a survey has been conducted in Turkey in some of the universities either offering web-based education or are interested in studies in this field.The aim of this survey is to analyze from system design point of view the studies carried out in our universities on this matter and to get a picture of the existing situation.The directed questions aiming this were prepared by taking into consideration of the three stages of system design subsystem, i.e. administrative design, educational design, and technological design. It is intended for the result of this survey to shed light to the new-coming institutions in this field. As a matter of fact, each stage of this subsystem is a survey item itself and should be researched one by one in other studies.Furthermore, for individuals interested in distance education and web-based distance education and for people newly involved in this matter, this thesis is intended to be a reference material and to serve this purpose the sections are prepared containing the basic information accordingly. Nevertheless, since most of the information regarding system design are prepared without taking into consideration the disabled people, the relevant information are not complete. In another study, the offering of the web-based education to the disabled people, especially for deaf, hard of hearing or speech impaired, and blind students, has to be investigated.Finally, in this thesis the proposed model for the Web-Based Distance Education, as being a basic and conceptual model, has a flexible structure; i.e., suitable for all the institutions and establishments intending to offer the web-based education.What is important here, is to exploit the potential sources within the institution that will display the required systematic approach.
Blackhole attacks in IoT networks
(01. Izmir Institute of Technology, 2020-12) Sokat, Barış; Ayav, Tolga; Ayav, Tolga; Erten, Yusuf Murat; 01. Izmir Institute of Technology
IoT technologies are very popular today, and they are used in almost every field. Therefore, the number of IoT devices used is increasing day by day. Like every field in computer networks, security is quite important in IoT networks. However, the resource-constrained nature of IoT devices makes the study of security measures for IoT networks very challenging. In the literature research conducted before this thesis study, it was seen that it can perform a wide variety of RPL-based attacks on IoT networks. One of these attacks is the blackhole attack. Although the black hole attack is functionally simple, the damage it causes in the network can be extremely destructive. As far as it is known, in addition to the limited number of studies in this field of attack, the black hole attack used in the studies in this field has also basic features. The basic feature mentioned here is that the attacker node that will perform a black hole attack drops all the packets that come to it. When the attacker node drops all incoming packets, it causes the topology to change in the network, the number of control messages to increase and the attacker node to be isolated from the network in a short time. However, blackhole attack can be combined with different attacks. Therefore, in this thesis, the node that will perform the black hole attack is designed to allow control messages to pass, while dropping all other packets. Here, it is aimed that the attacker node remains on the network for a longer time. As a result, as long as the attacker node is active, it will be able to drop more packets and the number of control messages in the network will be controlled since the topology does not change. With the black hole attack developed as a result of the simulation tests, the number of control messages released in the network was taken under control and it was observed that the attacker node could remain in the network throughout the simulation period. Thus, the effect of different types of black hole attacks on the network that can be developed has been revealed.
Block-chain based remote update for embedded devices
(Izmir Institute of Technology, 2019-12) Kaptan, Melike; Ayav, Tolga; Ayav, Tolga; Erten, Yusuf Murat
This research work is an attempt to devise a platform to send automatic remote updates for embedded devices. In this scenario there are Original Equipment Manufacturers (OEMs), Software suppliers, Block-Chain nodes, Gateways and embedded devices. OEMs and software suppliers are there to keep their software on IPFS (Inter Planetary File System) and send the meta-data and hashes of their software to the Block-Chain nodes in order to keep this information distributed and ready to be requested and used. There are also gateways which are also the members of the Block-Chain and IPFS network. Gateways are responsible for asking for a specific update for specific devices from IPFS database using the meta-data standing on the Block-Chain. And they will send those hashed secure updates to the devices. In order to provide a traceable data keeping platform gateway update operations are handled as a transactions in the second block-chain network which is the clock-chain of the gateways. In this study implementation of the two block chain shows us that, even though the calculation overhead of the member devices, with regulations specific to the applications block-chains provide applicable platforms.

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