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Determination of Measurement Noise, Conductivity Errors and Electrode Mislocalization Effects To Somatosensory Dipole Localization
(Biomedical Research, 2012) Şengül, Gökhan; Baysal, Uğur
Calculating the spatial locations, directions and magnitudes of electrically active sources of human brain by using the measured scalp potentials is known as source localization. An accu rate source localization method requires not only EEG data but also the 3-D positions and number of measurement electrodes, the numerical head model of the patient/subject and the conductivities of the layers used in the head model. In this study we computationally deter mined the effect of noise, conductivity errors and electrode mislocalizations for electrical sources located in somatosensory cortex. We first randomly selected 1000 electric sources in somatosensory cortex, and for these sources we simulated the surface potentials by using av erage conductivities given in the literature and 3-D positions of the electrodes. We then added random noise to measurements and by using noisy data; we tried to calculate the positions of the dipoles by using different electrode positions or different conductivity values. The esti mated electrical sources and original ones are compared and by this way the effect of meas urement noise, electrode mislocalizations and conductivity errors to somatosensory dipole lo calization is investigated. We conclude that for an accurate somatosensory source localization method, we need noiseless measurements, accurate conductivity values of scalp and skull lay ers and the accurate knowledge of 3-D positions of measurement sensors.
Ict Usage Characteristics and Computer Security
(PEOPLE: International Journal of Social Sciences, 2018) Akman, İbrahim; Bostan, Atila
Although acquired-user security habits and user security awareness are qualified as the feeblest components in assuring the information and communication technologies security, they are deemed to be inevitable as well. While the technology in information processing domain efforts its best in establishing the highest plausible security, user awareness is still referred as the key component. Human demographic factors, ICT usage frequency might have correlation with security related behavior routines, this dimension not to be known yet. Hence, in this study we examined the influence of ICT usage characteristics on secure computer usage behaviors. In order to investigate this relation, a survey was carried out with the participation of 466 individuals from diverse layers of the community. The results demonstrated that statistically noteworthy relations exist between several socio-demographic features, frequency and reason of ICT usage factors and secure computer usage.
Classification of Parasite Egg Cells Using Gray Level Cooccurence Matrix and Knn.
(Biomedical Research, 2016) Şengül, Gökhan
Parasite eggs are around 20 to 80 μm dimensions, and they can be seen under microscopes only and their detection requires visual analyses of microscopic images, which requires human expertise and long analysis time. Besides visual analysis is very error prone to human procedures. In order to automatize this process, a number of studies are proposed in the literature. But there is still a gap between the preferred performance and the reported ones and it is necessary to increase the performance of the automatic parasite egg classification approaches. In this study a learning based statistical pattern recognition approach for parasite egg classification is proposed that will both decrease the time required for the manual classification by an expert and increase the performance of the previously suggested automated parasite egg classification approaches. The proposed method uses Gray-Level Co-occurrence Matrix as the feature extractor, which is a texture based statistical method that can differentiate the parasite egg cells based on their textures, and the k-Nearest Neighbourhood (kNN) classifier for the classification. The proposed method is tested on 14 parasite egg types commonly seen in humans. The results show that proposed method can classify the parasite egg cells with a performance rate of 99%.
Unidirectional Data Transfer: a Secure System To Push the Data From a High Security Network To a Lower One Over an Actual Air-Gap
(International Journal of Scientific Research in Information Systems and Engineering, 2017) Şengül, Gökhan; Bostan, Atila; Karakaya, Murat
The term “air-gap” is typically used to refer physical and logical separation of two computer networks. This type of a separation is generally preferred when the security levels of the networks are not identical. Although the security requirements entail parting the data networks, there is a growing need for fast and automatic transfer of data especially from high-security networks to low-security ones. To protect security sensitive system from the risks originating from low-security network, unidirectional connections that permit the data transfer only from high to low-security network, namely information-diodes, are in use. Nonetheless, each diode solution has its drawbacks either in performance or security viewpoints. In this study, we present a unidirectional data transfer system in which the primary focus is data and signal security in technical design and with a plausible and adaptable data transfer performance. Such that the networks do not touch each other either in physically or logically and the transfer is guaranteed to be unidirectional. Apart from avoiding the malicious transmissions from low to high-security network, we claim that the proposed data diode design is safe from emanation leakage with respect to the contemporary sniffing and spoofing techniques.
Using Learning Style Theory in Remote Laboratory Applications
(IEEE, 2007) Tokdemir, Gül; Çağıltay, Nergiz
Studies have shown that, while learning different concepts, people sometimes use different approaches. These different approaches define individual learning styles. Understanding learning style differences is thus an important step in improving performance of the individuals and educational institutions. In this study, a learning style assessment tool was used to examine the relationship between students’ learning styles and their performance in engineering education programs of Atilim University. 329 students (55 female) participated in this study. At their first year in the program, students’ learning styles are measured by a learning style assessment tool developed by David Kolb. The results show that, at the Atilim University’s engineering education program, most of the students are having assimilator type of learning style (45%). Convergers (27%) and divergers (22%) follow the assimilators. The number of accommodators is very limited (5%). This information can be used to create adaptive teaching environments in distance education courses.
Biometric Verification on E-Id Secure Access Devices: a Case Study on Turkish National E-Id Card Secure Access Device Specifications
(International Journal of Information Security Science, 2017) Bostan, Atila; Şengül, Gökhan; Karakaya, Murat
Biometric verification on e-ID cards requires clear procedures and standards be defined, especially when the access devices are anticipated to be produced commercial companies. Turkish national e-ID card project has reached the dissemination step. Now the commercial companies are expected to produce and market e-ID card access devices which will conduct secure electronic identity verification functions. However, published standards specifying e-ID card-access-device requirements are ambiguous on biometric verification procedures. In this study, we intended to attract scientific interest to the problems identified in the current design of biometric verification on Turkish national e-ID cards and proposed several verification alternatives which enables the production of e-ID card access devices in a commercial-competition environment.
Distance Laboratory Applications ERRL: A Study on Radio Communication in Electronic Field
(IEEE, 2008) Aydın, Cansu Çiğdem; Özyurt, E.; Aydın, Elif; Çağıltay, Nergiz; Özbek, Mehmet Efe; Alparslan, Ceren; Kara, Ali
In the last decade, the effect of internet usage in education is gradually increased. When we look from academic perspective, the new technologies provided alternatives for students learning. As distance education becomes important everyday, the indispensable elements of teaching and education, laboratories must be reachable via remote connection. Consequently, the education that is going to be given to the students will be more flexible with respect to place and time constraints and students can reach laboratory facilities at any time and anywhere not only in lectures and practical hours. In this study, European Remote Radio Laboratory (ERRL) which is a distance remote Radio Frequency (RF) laboratory designed for electrical-electronics students, is described generally. The software architecture, infrastructure and experiment that can be done with a remote connection have been described.
Students’ Preferences on Web-Based Instruction: Linear or Non-Linear
(2006) Çağıltay, Nergiz; Yıldırım, Soner; Aksu, Meral
This paper reports the findings of a study conducted on a foreign language course at a large mid-west university in the USA. In the study a web-based tool which supports both linear and non-linear learning environments was designed and developed for this course. The aim of this study was to find out students’ preferences pertaining to the learning environment and to address the factors affecting their preferences. The results of this study showed that the individual characteristics of the students affected their preferences on the learning path (linear or non-linear).
Remote Laboratory Development as an Action Research: a Case Study
(2012) Çağıltay, Nergiz; Tokdemir, Gül; Aydın, Elif; Kara, Ali
This work presents a case study about how action research (AR) has been conducted in developing a real-life educational system. An explanation is given of the modified implementation of the classical AR methodology, based on the requirements of a remote laboratory system developed for the vocational training of students in higher education. This study reports a successful implementation of AR stages which established for the development process of a remote laboratory system along with the design of several research questions explored in each step of the system development process. It is believed that the outcomes of the study will help AR implementers to organize their research objectives, more appropriately, by addressing the organizational problems. The results of this study are also expected to guide the AR implementers to better integrate their research in solving domain specific practical problems.
Customizing Ssl Certificate Extensions To Reduce False-Positive Certificate Error/Warning Messages
(International Journal of Information Security Science, 2016) Tarazan, Şafak; Bostan, Atila
In today’s Internet world, X.509 certificates are commonly used in SSL protocol to provide security for web-based services by server/client authentication and secure communication. Although SSL protocol presents a technical basis, this web security largely depends on user awareness of security measures as well. There are significant number of scientific studies in the literature reporting that the count of invalid or self-signed certificate usage in today’s Internet can not be overlooked. At the same time, quite a number of studies place emphasis on the acquired indifference towards certificate warning messages which are popped up by web browsers when visiting web pages with invalid or self-signed certificates. In this study, with the importance of user’s daily practices in developing habits in mind, we studied a modification of X.509 certificates in order to reduce the number of false-positive certificate-warning pop ups in order to reduce gaining faulty usage habit of invalid certificates.

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