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Öğe The Analysis of Firewall Policy Through Machine Learning and Data Mining(Springer, 2017) Ucar, Erdem; Ozhan, ErkanFirewalls are primary components for ensuring the network and information security. For this purpose, they are deployed in all commercial, governmental and military networks as well as other large-scale networks. The security policies in an institution are implemented as firewall rules. An anomaly in these rules may lead to serious security gaps. When the network is large and policies are complicated, manual cross-check may be insufficient to detect anomalies. In this paper, an automated model based on machine learning and high performance computing methods is proposed for the detection of anomalies in firewall rule repository. To achieve this, firewall logs are analysed and the extracted features are fed to a set of machine learning classification algorithms including Naive Bayes, kNN, Decision Table and HyperPipes. F-measure, which combines precision and recall, is used for performance evaluation. In the experiments, kNN has shown the best performance. Then, a model based on the F-measure distribution was envisaged. 93 firewall rules were analysed via this model. The model anticipated that 6 firewall rules cause anomaly. These problematic rules were checked against the security reports prepared by experts and each of them are verified to be an anomaly. This paper shows that anomalies in firewall rules can be detected by analysing large scale log files automatically with machine learning methods, which enables avoiding security breaches, saving dramatic amount of expert effort and timely intervention.Öğe ATLIGSpace: Agent based P2P networking for pervasive systems(Int Inst Informatics & Systemics, 2007) Atlig, Cenk; Ucar, ErdemIn last few years, the current trends of networking has moved quickly from client-server type networking to P2P model. Content distribution based on P2P paradigm requires significant amount of system sources such as bandwidth. Constraints are even more severe for mobile systems. Some of these problems include, but not limited to, unpredictable access time (latency), higher packet loss ratio and limited energy sources in these systems. In this work, we put forward a new framework that uses mobile agents to minimize traffic of mobile devices by the use of a loosely-coupled communication paradigm. Loosely-coupled communication is used to make our system uncoupled both temporally and spatially. To illustrate the characteristics of our environment, we measure the traffic, packet loss ratio and energy consumption of the simulated system.Öğe Call Admission Control Jointly with Resource Reservation in Cellular Wireless Networks(Springeropen, 2010) Bozkurt, Aytul; Akdeniz, Rafet; Ucar, ErdemTo efficiently utilize the total resources and to serve mobile users demanding for different types of service, system resource utilization of these services should be considered, and efficient resource management techniques should be developed. In this paper, we propose a new call admission control (CAC) scheme jointly with resource management by considering the two service types: prioritized calls and nonprioritized calls. Proposed scheme limits the new and handoff prioritized and non-prioritized call arrivals according to call-level quality of service (QoS) requirements. By searching algorithm, admission parameters are obtained optimally and required QoS are guaranteed. Due to high priority of the prioritized calls, the admittance of non-prioritized calls into channel is restricted, while prioritized calls are admitted as long as there is sufficient bandwidth. To evaluate the performance of the proposed CAC scheme, we have compared the numerical results from the analytical model with those of New Call Bounding scheme. It is shown that the proposed CAC scheme uses the resources effectively and improves all the upper-bound QoS requirements with respect to the New Call Bounding scheme for prioritized and non-prioritized users.Öğe Call Admission Control Policy for Integration of Voice/Data Traffic in Cellular Mobile Networks(IEEE Computer Soc, 2010) Bozkurt, Aytul; Ucar, Erdem; Akdeniz, RafetIn integrated voice/data cellular mobile networks, the most important consideration is to utilize the resources in an efficient way and maintain the required quality of service (QoS). In this paper, we proposed a new call admission control scheme for improving efficiency of resource utilization. Proposed scheme restricts the new and handoff voice and data calls arrived to system by finding the optimal threshold number of new and handoff voice and data calls allowed in system according to admission criters such as maximum data response time, voice and data blocking and dropping probabilities. From the numerical analysis, we observed that required call-level QoS for both voice and data calls is provided and upper bound of data response time is guaranteed to data calls. Also taking the required minimum bandwith need of voice calls in different values, we evaluated the performance improvements of data calls.Öğe Can obstructive apnea and hypopnea during sleep be differentiated by using electroencephalographic frequency bands? Statistical analysis of receiver-operator curve characteristics(Tubitak Scientific & Technological Research Council Turkey, 2011) Ucar, Erdem; Sut, Necdet; Gulyasar, Tevfik; Umut, Ilhan; Ozturk, LeventAim: To investigate whether electroencephalographic (EEG) frequency bands are applicable in distinguishing abnormal respiratory events such as obstructive apnea and hypopnea in patients with sleep apnea. Materials and methods: The polysomnographic recordings of 20 patients were examined retrospectively. EEG record segments were taken from C4-A1 and C3-A2 channels and were analyzed with software that uses digital signal processing methods, developed by the study team. Percentage values of delta, theta, alpha, and beta frequency bands were evaluated through discriminant and receiver-operator curve (ROC) analysis to distinguish between apneas and hypopneas. Results: For the G4-A1 channel, delta (%) provided the highest discriminative value (AUG = 0.563; P < 0.001); on the other hand, alpha (%) gave the lowest discriminative value (AUG = 0.519; P = 0.041). Likewise, whereas for the C3-A2 channel delta (%) gave the highest discriminative value (AUG = 0.565; P < 0.001), alpha produced the lowest discriminative value (AUG = 0.501; P = 0.943). Conclusion: As a result of discriminant analysis, the accurate classification rate of hypopneas was 44.8% and the accurate classification of obstructive apneas was 63.5%. Of the 4 frequency bands, the most significant was delta. The predictive values were not at significance level.Öğe Cyprus international conference on educational research the effects of computer asssited simulations of physics experiments on learning(Elsevier Science Bv, 2012) Civelek, Turhan; Ucar, Erdem; Gokcol, OrhanThe main goal of this study is to present the significant difference between utilization of simulations of physics experiment during lectures and traditional physics lecture. Two groups of 115 students were selected for the purpose of the study. The same subjects have been taught to both groups, while a group of 115 had their lectures in science and technology class supported by physics experiment simulations for a month, the other group of 115 had their lectures in a traditional way. The research has been conducted in Izzet 'Inver highs school in Istanbul, Gungoren. The main resource of this research is the data collected through surveys. The survey is a result of the literature and the suggestions of the experts on the topic. Thirty questions were prepared under ten topics. Two different surveys were conducted during the data collection. While the first survey questions focused on the effects of traditional lecturing on students, the second survey questions were targetirtg the effects of lecturing via the support of psychics experiment simulations. The data collected as a result of the survey which was coded in to SPSS Software and statistical analyses was conducted. In order to test the significant difference between the means t-test was utilized. 0.05 was chosen as the significance level. As a result of the analyses utilized, significant differences were found in their satisfaction on class materials, in their motivation, in their learning speed, in their interest in the class, and in their contribution to the class. In findings such as the effect on students' learning, information availability, organization of information, students' integration to the class and gaining different point of views lectures supported by physics experiment simulations is significantly different from traditional lecturing. As the result of the literature review and the statistical analyses, lectures supported via physics experiment simulations seem to be more effective than traditional lecturing in science classes, in issues such as variability of approaches, student concept delusions, laboratory applications, utilization of information technologies and simulations. (C) 2012 Published by Elsevier Ltd.Öğe DETECTION OF DRIVER SLEEPINESS AND WARNING THE DRIVER IN REALTIME USING IMAGE PROCESSING AND MACHINE LEARNING TECHNIQUES(Lublin Univ Technology, Poland, 2017) Umut, Ilhan; Aki, Ozan; Ucar, Erdem; Ozturk, LeventThe aim of this study is to design and implement a system that detect driver sleepiness and warn driver in real-time using image processing and machine learning techniques. Viola-Jones detector was used for segmenting face and eye images from the cameraacquired driver video. Left and right eye images were combined into a single image. Thus, an image was obtained in minimum dimensions containing both eyes. Features of these images were extracted by using Gabor filters. These features were used to classifying images for open and closed eyes. Five machine learning algorithms were evaluated with four volunteer's eye image data set obtained from driving simulator. Nearest neighbor IBk algorithm has highest accuracy by 94.76% while J48 decision tree algorithm has fastest classification speed with 91.98% accuracy. J48 decision tree algorithm was recommended for real time running. PERCLOS the ratio of number of closed eyes in one minute period and CLOSDUR the duration of closed eyes were calculated. The driver is warned with the first level alarm when the PERCLOS value is 0.15 or above, and with second level alarm when it is 0.3 or above. In addition, when it is detected that the eyes remain closed for two seconds, the driver is also warned by the second level alarm regardless of the PERCLOS value. Designed and developed real-time application can able to detect driver sleepiness with 24 FPS image processing speed and 90% real time classification accuracy. Driver sleepiness were able to detect and driver was warned successfully in real time when sleepiness level of driver is achieved the defined threshold values.Öğe Effects of a Haptic Augmented Simulation on K-12 Students' Achievement and their Attitudes towards Physics(Modestum Ltd, 2014) Civelek, Turhan; Ucar, Erdem; Ustunel, Hakan; Aydin, Mehmet KemalThe current research aims to explore the effects of a haptic augmented simulation on students. achievement and their attitudes towards Physics in an immersive virtual reality environment (VRE). A quasi-experimental post-test design was employed utilizing experiment and control groups. The participants were 215 students from a K-12 school in Istanbul, Turkey. The students were split into two groups and each group were respectively taught the subject, mass gravity in the solar system., employing traditional instructional methods for the control group and, as a treatment, utilizing a haptic force feedback application in a VRE for the experiment group. The data was gathered through an attitude questionnaire and an achievement test was analyzed administering descriptive and comparative analyses. Findings illustrated that use of a haptic force feedback application in a VRE had a significant and positive effect on students. achievement, as well as on their motivation, encouragement, autonomy, and learning quality.Öğe Effects of using a force feedback haptic augmented simulation on the attitudes of the gifted students towards studying chemical bonds in virtual reality environment(Taylor & Francis Ltd, 2017) Ucar, Erdem; Ustunel, Hakan; Civelek, Turhan; Umut, IlhanThe aim of this study is to identify the effects of force feedback haptic applications developed in virtual reality environments (VREs), which is an important field of study in computer science and engineering, on gifted students' attitudes towards chemistry education in learning process. A 3D 6 DOF (Degree of Freedom) haptik device (Phantom Omni) has been used to develop the algorithm in this study. It can be used to transmit force and motion using a haptic device. Visual C++ was choosen as the software development environment. OpenGL and Haptic Device Application Programming Interface have been used for rendering graphics. At the 3D image creation state Wrap 1200, which is a kind of head-mounted display, has been chosen. The sample of this study consists of 52 students identified as gifted and are attending 6th and 7th grades at the Istanbul Science & Art Center in Istanbul. The experimental group studied chemical bonds using an application developed by using a force feedback haptic device in VRE and the control group studied it by traditional teaching methods. The study reveals that there is a relation between using force feedback haptic applications which are developed in VREs and gifted students' attitudes towards educational programs.Öğe The factors effecting students' PC game types preferences(Elsevier Science Bv, 2012) Ustunel, Hakan; Meral, Mustafa; Ucar, Erdem; Umut, IlhanThe aim of this study is to investigate the attitude of students' pc game and theme preferences (action, strategy, sports etc.). The data were collected from 722 students at the age of 11-14 in Istanbul and was analyzed using by Weka 3.7.0 that is a popular suite of machine learning software. At this point some classifiers and learning algorithms were used for determining which students play which types of games. the study reveals that there is a relation between students PC game types preferences and their demographic characteristics and the independent variables. The software predicts the game types truly in acceptable ratio.Öğe HYBRID ENERGY PRODUCTION AND DELIVERY USING MULTIPLE RENEWABLE SOURCES(IEEE Computer Soc, 2009) Umut, Ihan; Ucar, Erdem[Abstract Not Available]Öğe An Inter-Domain Attack Mitigating Solution(Tubitak Scientific & Technological Research Council Turkey, 2020) Akin, Gokhan; Buk, Ozan; Ucar, ErdemOnline services on the Internet are increasing day by day, and in parallel, the number of cyber-attacks is rapidly increasing. These attacks are not always about data theft, but they can cause severe damage by denial of service attacks. Intrusion Prevention System products that many organizations use at the border of their enterprise networks are not strong enough to protect against DoS attacks. The typical way to mitigate such attacks is to get support from a service provider. However, a service provider only provides solutions for the traffic originating from itself. If the source of attack is in another ISP domain, it is possible to inform that ISP via phone or e-mail. As a result, the source of the attack is blocked by the manual intervention of the service provider whose domain hosts it. Border Gateway Protocol (BGP) based solutions are also available for automating a blocking system, but not all enterprise networks support BGP. In this research, we have developed a centralized automation solution for software defined network (SDN) environments that is capable of preventing cyber-attacks at the source of attack. This solution does not require any BGP support. Non-SDN environments can also use this attack mitigation and notification system. In the long run, we may use this system to create a national protection shield in order to mitigate Cybersecurity attacks.Öğe A novel algorithm for extracting the user reviews from web pages(Sage Publications Ltd, 2017) Ucar, Erdem; Uzun, Erdinc; Tufekci, PinarExtracting the user reviews in websites such as forums, blogs, newspapers, commerce, trips, etc. is crucial for text processing applications (e.g. sentiment analysis, trend detection/monitoring and recommendation systems) which are needed to deal with structured data. Traditional algorithms have three processes consisting of Document Object Model (DOM) tree creation, extraction of features obtained from this tree and machine learning. However, these algorithms increase time complexity of extraction process. This study proposes a novel algorithm that involves two complementary stages. The first stage determines which HTML tags correspond to review layout for a web domain by using the DOM tree as well as its features and decision tree learning. The second stage extracts review layout for web pages in a web domain using the found tags obtained from the first stage. This stage is more time-efficient, being approximately 21 times faster compared to the first stage. Moreover, it achieves a relatively high accuracy of 96.67% in our experiments of review block extraction.Öğe Protocol Design for Secure Communication in WSN(Assoc Information Communication Technology Education & Science, 2017) Ata, Oguz; Balik, Hasan H.; Ucar, ErdemWireless sensor networks are widely used in military applications, monitoring of environmental information, health, domestic, and industrial applications. Despite of these wide usages, the main problem of this kind of topologies is the increasing security needs. This paper has been targeted to develop a novel message identity validation protocol in WSN to provide secure data identity in order to decrease some security threads. Introduced protocol also includes key distribution, node identification, sensitivity mechanisms, to strengthen the introduced method. Moreover, there is also repeated symmetrical key update mechanism without the need to synchronization. Finally, the developed protocol has also been tested in terms of various network parameters.Öğe Reconstructive sensing circuit for complementary resistive switches-based crossbar memories(Tubitak Scientific & Technological Research Council Turkey, 2016) Karakulak, Ertugrul; Mutlu, Resat; Ucar, ErdemComplementary resistive switches (CRSs) are suggested as an alternative to one-cell memristor memories to decrease leakage currents. However, their sensing is more difficult and complex than one-cell memristor memories. A method has been given for sensing their state using only DC voltages in the literature. However, in this strategy, sensing one of the logic states results in the destruction of the state and the destroyed state must be written again. To the best of our knowledge, a circuit with this sensing strategy does not exist in the literature yet. In this paper, such a circuit employing this method, which is able to read the CRS cells and able to reconstruct their data if the data are destroyed, is given. A new CRS model is also constructed in this paper and used for simulations to verify the operation of the circuit. The circuit is simulated using Simulink. We expect this circuit implementation to find use in the design and testing of CRS cells.Öğe Sneak path current equivalent circuits and reading margin analysis of complementary resistive switches based 3D stacking crossbar memories(Soc Microelectronics, Electron Components Materials-Midem, 2014) Karakulak, Ertugrul; Mutlu, Resat; Ucar, ErdemSneak path currents of resistive memories is an important issue. They increase with increasing memory size and should be minimized for a usable resistive memory. The complementary resistive cells have been suggested as an alternative to one-cell resistive memories to decrease leakage currents. In literature, multilayer resistive memory topologies have also been inspected to minimize leakage currents. Recently, feasibility of 3D resistive RAMs is also inspected. However, to the best of our knowledge, no one has given equivalent leakage circuit models for complementary resistive switches based 3D resistive RAMs yet. In this study, equivalent leakage circuit models for different layers of a 3D resistive RAM with complementary resistive cells have been given and their leakage resistance and reading margins are compared to that of one layer crossbar memory. Some interesting and crucial results are obtained. Alternative complementary resistive switches based 3D resistive RAM topologies with insulating layer(s) for minimized leakage currents are suggested.Öğe Techno-Economic Evaluation of a Hybrid PV-Wind Power Generation System(Taylor & Francis Inc, 2013) Dursun, Bahtiyar; Gokcol, Cihan; Umut, Ilhan; Ucar, Erdem; Kocabey, SureyyaThis article investigates the possibility of providing electricity from solar/wind hybrid systems for a remote location with no electricity connection in the city of Edirne in the westernmost province of Turkey in order to decrease the high cost of utilizing only stand-alone diesel system and to achieve considerable fuel savings. In this study, National Renewable Energy Laboratory's (NREL) HOMER (Hybrid Optimization Model for Electric Renewables) software is used to perform the techno-economic feasibility of such hybrid systems considering both solar data and wind data. Additionally, the contribution of solar and wind on energy production, cost of energy, and total operating hours of diesel generator is examined for the optimal hybrid configurations. Furthermore, fuel savings and reduction in carbon emissions of different hybrid systems are investigated. Finally, suitability of utilizing hybrid solarwind energy system over stand-alone diesel system is discussed mainly based on different solar global irradiances, wind speed, and diesel price.Öğe Visualization of Turkish for Autistic and Mentally Retarded Children(IEEE, 2008) Kilicaslan, Yilmaz; Ucar, Ozlem; Ucar, Erdem; Guner, Edip SerdarThe use of software technologies for supporting the education of disabled children continues to increase both in quantity and quality. L2I is a set of computer programs that assists the education and training of autistic and mentally retarded children. These children are known to have difficulties in grasping fairly abstract concepts. L2I is intended to circumvent the abstractness of linguistically encoded conceptual structures via visual images. The software has also the potential to teach and/or assist a variety of basic skills including reading, writing and communicating. Each component constituting L2I has been tested with a group of students with autism and mental retardation in a special education center. In the light of the observations made over these tests, this paper presents how L2I can be benefited from in a special education program.
