Browsing by Author "Şengül,G."
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Conference Object Citation Count: 0Application of Kalman filter for the estimation of human head tissue conductivities;(2011) Şengül, Gökhan; Baysal,U.; Computer EngineeringIn this study Extended Kalman Filtering is proposed for the estimation of human head tissue conductivities by using EEG data. The proposed method first linearizes the relationship between the tissue conductivities and surface potentials (EEG measurements) and then iteratively estimates the tissue conductivities. In the study the mathematical background of the proposed method is presented and then performance of the proposed method is investigated by a simulation study. In the simulation study a three layered realistic head model (composed of scalp, skull and brain compartments) obtained from MR images of a real patient is used. The surface potential is calculated by using an arbitrarily chosen conductivity distribution. Then conductivity estimation is iteratively performed by using the calculated potentials and at each iteration relative error rates are calculated by comparing the orginal conductivities and estimated ones. It is found that the relative error rates decrease below of 1% after five iterations. © 2011 IEEE.Article Citation Count: 1Computer vision based automated cell counting pipeline: A case study for HL60 cancer cell on hemocytometer(Scientific Publishers of India, 2018) Özkan, Akın; İşgör,S.B.; Şengül, Gökhan; İşgör,Y.G.; İşgör, Sultan Belgin; Department of Electrical & Electronics Engineering; Computer Engineering; Chemical EngineeringCounting of cells can give useful information about the cell density to understand the concerning cell culture condition. Usually, cell counting can be achieved manually with the help of the microscope and hemocytometer by the domain experts. The main drawback of the manual counting procedure is that the reliability highly depends on the experience and concentration of the examiners. Therefore, computer vision based automated cell counting is an essential tool to improve the accuracy. Although the commercial automated cell counting systems are available in the literature, their high cost limits their broader usage. In this study, we present a cell counting pipeline for light microscope images based on hemocytometer that can be easily adapted to the various cell types. The proposed method is robust to adverse image and cell culture conditions such as cell shape deformations, lightning conditions and brightness differences. In addition, we collect a novel human promyelocytic leukemia (HL60) cancer cell dataset to test our pipeline. The experimental results are presented in three measures: recall, precision and F-measure. The method reaches up to 98%, 92%, and 95% based on these three measures respectively by combining Support Vector Machine (SVM) and Histogram of Oriented Gradient (HOG). © 2018, Scientific Publishers of India. All rights reserved.Conference Object Citation Count: 0A fully automatic photogrammetric system design using a 1.3 MP web camera to determine EEG electrode positions;(2010) Şengül, Gökhan; Baysal,U.; Computer EngineeringIn this study a fully automatic fotogrammetric system is designed to determine the EEG electrode positions in 3D. The proposed system uses a 1.3 MP web camera rotating over the subject's head. The camera is driven by a step motor. The camera takes photos in every 7.20 angles during the rotation. In order to realize full automation, electrodes are labeled by colored circular markers and an electrode identification algorithm is develeoped for full automation. The proposed method is tested by using a realistic head phantom carrying 25 electrodes. The positions of the test electrodes are also measured by a conventional 3-D digitizer. The measurements are repeated 3 times for repeatibility purposes. It is found that 3-d digitizer localizes the electrodes with an average error of 8.46 mm, 7.63 mm and 8.32 mm, while the proposed system localizes the electrodes with an average error of 1.76 mm, 1.42 mm and 1.53 mm. ©2010 IEEE.Conference Object Citation Count: 1An IoT application for locating victims aftermath of an earthquake(Institute of Electrical and Electronics Engineers Inc., 2017) Şengül, Gökhan; Gökçay, Erhan; Gökçay,E.; Karakaya, Kasım Murat; Software Engineering; Computer EngineeringThis paper presents an Internet of Things (IoT) framework which is specially designed for assisting the research and rescue operations targeted to collapsed buildings aftermath of an earthquake. In general, an IoT network is used to collect and process data from different sources called things. According to the collected data, an IoT system can actuate different mechanisms to react the environment. In the problem at hand, we exploit the IoT capabilities to collect the data about the victims before the building collapses and when it falls down the collected data is processed to generate useful reports which will direct the search and rescue efforts. The proposed framework is tested by a pilot implementation with some simplifications. The initial results and experiences are promising. During the pilot implementation, we observed some issues which are addressed in the proposed IoT framework properly. © 2017 IEEE.Conference Object Citation Count: 3Self archiving in Atilim University(2012) Ertürk, Korhan Levent; Şengül,G.; Şengül, Gökhan; Information Systems Engineering; Computer EngineeringSelf archiving is defined as storing the scientific research outputs in researchers' own web pages/sites, organizational web sites or institutional repositories. In this study the self archiving activities of academicians of AtIlIm University are investigated. For the purpose of the study the web pages of the university, personal web pages of the academicians and open repository of the university are explored. We found the details of 2176 academic activities of the instructors in web pages. More than half of these activities (1147 - 53%) consist of refereed journal papers. Almost a quarter of the instructors saved their research outputs in the university's open repository. Yet, those instructors have not published their works in their personal web pages or institutional web pages. Only 4% of the works are published in personal/organizational web pages. According to the results obtained, the usage of institutional repository is the common self archiving method in the AtIlIm University. On the other hand, the personal/organizational web pages should be as a point of attraction in self archiving. While discussing the efficient usage of the institutional repository, we suggest that the social networks as a meeting point should include links to personal/institutional web pages containing academicians' papers. © 2012 Springer-Verlag.