Bilgisayar Mühendisliği Bölümü

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Citation - WoS: 2
Citation - Scopus: 2
Guest Editorial: Gamification and Persuasive Games for Software Engineering
(inst Engineering Technology-iet, 2019) O'Connor, Rory V.; Colomo-Palacios, Ricardo; Clarke, Paul; Yilmaz, Murat
Citation - Scopus: 3
Oscillation for a Nonlinear Dynamic System on Time Scales
(2011) Mert, R.; Erbe, L.
We study the oscillation properties of a system of two first-order nonlinear equations on time scales. This form includes the classical Emden-Fowler differential and difference equations and many of its extensions. We generalize some well-known results of Atkinson, Belohorec, Waltman, Hooker, Patula and others and also describe the relation to solutions of a delay-dynamic system. © 2011 Taylor & Francis.
Classification of Linked Data Sources Using Semantic Scoring
(Ieice-inst Electronics information Communication Engineers, 2018) Dogdu, Erdogan; Kodaz, Halife; Yumusak, Semih
Linked data sets are created using semantic Web technologies and they are usually big and the number of such datasets is growing. The query execution is therefore costly, and knowing the content of data in such datasets should help in targeted querying. Our aim in this paper is to classify linked data sets by their knowledge content. Earlier projects such as LOD Cloud, LODStats, and SPARQLES analyze linked data sources in terms of content, availability and infrastructure. In these projects, linked data sets are classified and tagged principally using VoID vocabulary and analyzed according to their content, availability and infrastructure. Although all linked data sources listed in these projects appear to be classified or tagged, there are a limited number of studies on automated tagging and classification of newly arriving linked data sets. Here, we focus on automated classification of linked data sets using semantic scoring methods. We have collected the SPARQL endpoints of 1,328 unique linked datasets from Datahub, LOD Cloud, LODStats, SPARQLES, and SpEnD projects. We have then queried textual descriptions of resources in these data sets using their rdfs: comment and rdfs: label property values. We analyzed these texts in a similar manner with document analysis techniques by assuming every SPARQL endpoint as a separate document. In this regard, we have used WordNet semantic relations library combined with an adapted term frequency-inverted document frequency (tfidf) analysis on the words and their semantic neighbours. In WordNet database, we have extracted information about comment/label objects in linked data sources by using hypernym, hyponym, homonym, meronym, region, topic and usage semantic relations. We obtained some significant results on hypernym and topic semantic relations; we can find words that identify data sets and this can be used in automatic classification and tagging of linked data sources. By using these words, we experimented different classifiers with different scoring methods, which results in better classification accuracy results.
Citation - WoS: 1
Citation - Scopus: 2
Evaluation of Semantic Relatedness Measures for Turkish Language
(Springer international Publishing Ag, 2018) Sopaoglu, Ugur; Ercan, Gonenc
The problem of quantifying semantic relatedness level of two words is a fundamental sub-task for many natural language processing systems. While there is a large body of research on measuring semantic relatedness in the English language, the literature lacks detailed analysis for these methods in agglutinative languages. In this research, two new evaluation resources for the Turkish language are constructed. An extensive set of experiments involving multiple tasks: word association, semantic categorization, and automatic WordNet relationship discovery are performed to evaluate different semantic relatedness measures in the Turkish language. As Turkish is an agglutinative language, the morphological processing component is important for distributional similarity algorithms. For languages with rich morphological variations and productivity, methods ranging from simple stemming strategies to morphological disambiguation exists. In our experiments, different morphological processing methods for the Turkish language are investigated.
Citation - Scopus: 6
An Exploration of Individual Personality Types in Software Development
(Springer Verlag, 2014) O'Connor, R.V.; Clarke, P.; Yilmaz, M.
Previous research - using conventional psychometric questionnaires - has highlighted the importance of aligning compatible personality types in software development teams. However, there does not exist a dedicated, robust questionnaire instrument for revealing the pertinent personality types for software development practitioners. This study analyzes the validity and reliability of a 70-item (context dependent) personality-profiling questionnaire particularly developed to assess personality types of software practitioners. A systematic process of validation, using an iterative approach to questionnaire development, was employed. The questions were developed both with a qualitative analysis of interview data, and based on the opinions of expert reviewers who revised the items through a set of examination. To investigate how stable the questions and reproducible the results, we measured test-retest reliability of the instrument, yielding satisfactory results. The present study provided evidence for the construct validity of the instrument. Ultimately, an initial comparison of the results delivered by the instrument demonstrated positive correlations with the findings acquired with well-known personality assessment instrument, i.e. the big five personality questionnaire. © Springer-Verlag Berlin Heidelberg 2014.
Face Photograph Recognition via Generation from Sketches using Convolutional Neural Networks
(2019) Karasolak, Mustafa; Choupani, Roya
Face photo-sketch matching is an important problem for law enforcement agencies in terms of identifying suspects. In this study, a new sketch-photo generation and recognition technique is proposed by using residual convolutional neural network architecture. The suggested RCNN architecture consists of 6 convolutions, 6 ReLU, 4 poolings, 2 deconvolution layers. The proposed architecture is trained with face photos and sketches. Sketches are supplied as an input to the RCNN architecture and, generated face photos are obtained as the output. Then, the generated face photos are compared with the photos of the people in the database. Structural Similarity Index (SSIM) is used to measure the pairwise similarity and the photo with the highest index score is matched. CUHK Face Sketch Database containing 188 images is tested. In the experiments, 148, 20, and 20 images are used for training, validation, and testing, respectively. Data augmentation applied to 148 training images produced 444 images. Experimental results show that the success of the training curve is 90.55% and the validation success is 91.1%. True face recognition success from generated face images with SSIM is 93.89% for CUHK Face Sketch database (CUFS) and 84.55% AR database.
Citation - WoS: 56
Citation - Scopus: 88
A Deep Neural-Network Based Stock Trading System Based on Evolutionary Optimized Technical Analysis Parameters
(Elsevier Science Bv, 2017) Ozbayoglu, Murat; Dogdu, Erdogan; Sezer, Omer Berat
In this study, we propose a stock trading system based on optimized technical analysis parameters for creating buy-sell points using genetic algorithms. The model is developed utilizing Apache Spark big data platform. The optimized parameters are then passed to a deep MLP neural network for buy-sell-hold predictions. Dow 30 stocks are chosen for model validation. Each Dow stock is trained separately using daily close prices between 1996-2016 and tested between 2007-2016. The results indicate that optimizing the technical indicator parameters not only enhances the stock trading performance but also provides a model that might be used as an alternative to Buy and Hold and other standard technical analysis models. (c) 2017 The Authors. Published by Elsevier B.V.
Citation - WoS: 24
Citation - Scopus: 27
Partially Coherent Airy Beam and Its Propagation in Turbulent Media
(Springer Heidelberg, 2013) Sermutlu, Emre; Eyyuboglu, Halil T.
The properties of partially coherent Airy beam propagating in turbulent media are investigated. Firstly the variations in the intensity profile and the location of the Airy beam peak with respect to dislocation and width parameters are examined. On the source plane, it is shown that there is a threshold value of the dislocation parameter which determines whether the beam peak will lie on the negative or positive side of the axis. The changes in source beam power and source beam size with respect to dislocation and width parameters are also examined. Then analysis is made for partially coherent Airy beam propagating in turbulence against variations in propagation distance, dislocation and width parameters, structure constant and partial coherence. It is found that the peak of the Airy beam will always shift to the right for increasing propagation distance. But this shift will become less as the dislocation and width parameters are increased. Finally it is shown that higher levels of turbulence and partial coherence will lead to more spreading and shift the beam peak more toward the on-axis position.
Cassandra ve MongoDB NoSQL Veri Tabanlarının Karşılaştırmalı Güvenlik Analizi
(2019) Saran, Murat; Saran, Nurdan
In this study, we analyze the security of two NoSQL databases, MongoDB 3.6.3 and Cassandra 3.11.1 in a multi-node configuration in two steps. The first step is a comparative study of both databases’ security features according to ten selected criteria from the literature. The second step is analyzing data encryption overhead using the Yahoo Cloud Serving Benchmark tool. This study will help decision-makers and researchers to realize the most crucial security features concerning NoSQL databases as well as to be able to analyze the NoSQL databases regarding the security features. Our security comparison results show that both databases have noteworthy security features. However, Cassandra takes the lead as it supports more security criteria. Besides, the encryption/decryption performance of the MongoDB business version is 53% faster than the Cassandra business version, and the average amount of data that the MongoDB business version can process per minute is 45% higher than the Cassandra business version. This result shows that it is more appropriate to use MongoDB in environments where encryption is required.
Citation - WoS: 22
Citation - Scopus: 21
Functionalizing Graphene by Embedded Boron Clusters
(Iop Publishing Ltd, 2008) Ozdogan, Cem; Kunstmann, Jens; Fehske, Holger; Quandt, Alexander
We present a model system that might serve as a blueprint for the controlled layout of graphene based nanodevices. The systems consists of chains of B-7 clusters implanted in a graphene matrix, where the boron clusters are not directly connected. We show that the graphene matrix easily accepts these alternating B-7-C-6 chains and that the implanted boron components may dramatically modify the electronic properties of graphene based nanomaterials. This suggests a functionalization of graphene nanomaterials, where the semiconducting properties might be supplemented by parts of the graphene matrix itself, but the basic wiring will be provided by alternating chains of implanted boron clusters that connect these areas.
Citation - WoS: 11
Citation - Scopus: 11
Diagnosis of Osteoarthritic Changes, Loss of Cervical Lordosis, and Disc Space Narrowing on Cervical Radiographs With Deep Learning Methods
(Turkish Joint Diseases Foundation, 2022) Tokdemir, Gul; Ureten, Kemal; Atalar, Ebru; Duran, Semra; Maras, Hakan; Maras, Yuksel
Objectives: In this study, we aimed to differentiate normal cervical graphs and graphs of diseases that cause mechanical neck pain by using deep convolutional neural networks (DCNN) technology. Materials and methods: In this retrospective study, the convolutional neural networks were used and transfer learning method was applied with the pre-trained VGG-16, VGG-19, Resnet-101, and DenseNet-201 networks. Our data set consisted of 161 normal lateral cervical radiographs and 170 lateral cervical radiographs with osteoarthritis and cervical degenerative disc disease. Results: We compared the performances of the classification models in terms of performance metrics such as accuracy,
Sanal Ofis Ortaminda Kod Gözden Geçirme ile Kod Degerlendirmesi
(CEUR-WS, 2016) Kaymak, M.; Yılmaz, Murat; Namiduru, M.; Tüzün, E.; Yilmaz, M.; Yazılım Mühendisliği
Citation - WoS: 32
Citation - Scopus: 43
A 3d Virtual Environment for Training Soccer Referees
(Elsevier Science Bv, 2019) Isler, Veysi; O'Connor, Rory V.; Clarke, Paul M.; Gulec, Ulas; Yilmaz, Murat
Emerging digital technologies are being used in many ways by and in particular virtual environments provide new opportunities to gain experience on real-world phenomena without having to live the actual real-world experiences. In this study, a quantitative research approach supported by expert validation interviews was conducted to determine the availability of virtual environments in the training of soccer referees. The aim is to design a virtual environment for training purposes, representing a real-life soccer stadium to allow the referees to manage matches in an atmosphere similar to the real stadium atmosphere. At this point, the referees have a chance to reduce the number of errors that they make in real life by experiencing difficult decisions that they encounter during the actual match via using the virtual stadium. In addition, the decisions and reactions of the referees during the virtual match were observed with the number of different fans in the virtual stadium to understand whether the virtual stadium created a real stadium atmosphere for the referees. For this evaluation, Presence Questionnaire (PQ) and Immersive Tendencies Questionnaire (ITQ) were applied to the referees to measure their involvement levels. In addition, a semi-structure interview technique was utilized in order to understand participants' opinions about the system. These interviews show that the referees have a positive attitude towards the system since they can experience the events occurred in the match as a first person instead of watching them from camera as a third person. The findings of current study suggest that virtual environments can be used as a training tool to increase the experience levels of the soccer referees since they have an opportunity to decide about the positions without facing the real-world risks.
Citation - WoS: 1
Citation - Scopus: 1
Fmml: a Feature Model Markup Language
(Amer inst Physics, 2011) Nabdel, Leili; Karatas, Ahmet Serkan; Oguztuzun, Halit; Dogru, Ali
Feature modeling is a common way of representing commonality and variability in Software Product Line Engineering. Alternative notations are available to represent feature models. Compared with graphical notations, text-based notations can be more amenable to automated processing and tool interoperability. In this paper, we propose an XML-based feature modeling language to represent extended feature models with complex relationships.
On the Oscillation of Solutions of a Nonlinear Dynamic System on Time Scales
(2012) Erbe, L.; Mert, Raziye; Mert, R.; Matematik
We study the oscillation properties of a system of two first-order nonlinear equations on time scales. This form includes the classical Emden-Fowler differential and difference equations and many of its extensions. We provide a corrected formulation of some earlier oscillation results as well as providing some new oscillation criteria. © Dynamic Publishers, Inc.
Citation - WoS: 10
Citation - Scopus: 10
Towards a Serious Game To Teach Iso/Iec 12207 Software Lifecycle Process: an Interactive Learning Approach
(Springer-verlag Berlin, 2015) Yilmaz, Murat; O'Connor, Rory V.; Aydan, Ufuk
ISO/IEC 12207 training is a key element to provide an ability to software development organizations for selecting a set of required processes, measuring the performance of these processes, and continuously improving them. Traditionally, such training is either performed by an expert individual to the software quality management personnel most likely in form of a seminar in a classroom environment. This may also be given by a qualified professional, such as a registered auditor. However, software requirements are usually subject to change, and therefore such training is not enough to teach the substantial details of the entire standard. This has led to increased reports of complications, which demotivates organization to use this standard. To improve the quality of traditional training, a 3D serious game was proposed. The preliminary idea here is that the training is utilized as a game that employs 3D office landscape to provide a realistic virtual environment for ensuring that the training will be based in a real-world-like environment. Before building a prototype for our serious game, we consulted five industrial experts whose works are related with ISO standards. To give these practitioners an opportunity to explore the conceptual design and raise some potential problems, the semi-structured interview method was used. Based on the suggestions of experts, proposed model of the serious game were revised. Taken together, initial results suggest that a serious game for teaching ISO/IEC 12207 should be useful for individuals who are interested in learning more about the standard.
Citation - WoS: 3
Citation - Scopus: 3
Towards a Quest-Based Contextualization Process for Game-Based Learning
(Acad Conferences Ltd, 2014) Yılmaz, Murat; Yilmaz, Murat; Saran, Murat; Saran, Murat; O'Connor, Rory; Yazılım Mühendisliği; Bilgisayar Mühendisliği
This study proposes a quest-based contextualization (QBC) process, which transforms part of a traditional lecture into a well-defined questing structure. The goal is to create a learning experience by using a systematic game-based questing approach. The QBC procedure is a set of sequential tasks defined by the game designer to reflect the instructional objectives of the course. It is formed as an interaction perspective from which a game system can be materialized, and which aims to improve the quality of the game flow and the user experience in a game-based learning environment. We claim that a game-based contextualization process can be used to restructure a traditional lecture in terms of educational quests. In particular, it was hypothesized that the design of such a quest-line should be constructed as a questing structure based on the chain of events, which are extracted from lecture notes. In the formulation of this design, the key events were discussed in an interview with an expert (i.e. content specialist) from a target field. This interview was transcribed, and further analyzed using an iterative qualitative approach as an interpretive analysis technique where an inductive proposition is considered for contextualization of data. This research used a thematic analysis methodology to explore the situations, which are suitable for questing and might be expandable into categories. Furthermore, questable points from the data were captured and situational elements and conversational key points were rigorously categorized. After building the initial mapping, we conducted a second interview with the same area expert to refine our preliminary findings. To evaluate our approach from the game design perspective, we sought advice from a small group of game design experts and practitioners who are recognized knowledgeable individuals in educational game development. Based on the opinion of four game design experts, the questing structure was revised and several game elements, such as extra battles, puzzles, and achievements, were added to support the elements of fun. Three of the experts argued that the proposed questing structure was highly educational, while the fourth claimed that such an improvement was partially important. These findings, while preliminary, suggested that a well-defined questing structure should be useful to improve the quality of a game-based learning environment.
Towards a Serious Game to Teach ISO/IEC 12207 Software Lifecycle Process: An interactive learning approach
(2015) Aydan, Ufuk; Yılmaz, Murat; O’Connor, Rory V.
ISO/IEC 12207 training is a key element to provide an ability to software development organizations for selecting a set of required processes, measuring the performance of these processes, and continuously improving them. Traditionally, such training is either performed by an expert individual to the software quality management personnel most likely in form of a seminar in a classroom environment. This may also be given by a suitability qualified professional, such as a registered auditor. However, software requirements are usually subject to change, and therefore such training is not enough to teach the substantial details of the entire standard. This has led to increased reports of complications, which demotivates organization to use this standard. To improve the quality of training, a 3D serious game was proposed for the software practitioners. The preliminary idea here is that the game employs 3D office landscape to provide a realistic virtual environment ensuring that the training will be based on real word like situations. Before building a prototype for our serious game, we consulted five industrial experts whose works are related with ISO standards. To give these practitioners an opportunity to explore the conceptual design and raise some potential problems, the semi-structured interview method was used. Based on the suggestions of experts, dynamics and mechanics of the proposed game were updated. Taken together, initial results suggest that a serious game for teaching ISO/IEC 12207 should be useful for individuals who are interested to learn more about the standard.
İmge İçine Bilgi Gizlemede Kullanılan LSB Yöntemlerinin Karşılaştırması
(2013) Saran, Nurdan; Olcay, Cem
Dijital imgeleri temel olarak kayıplı sıkı¸stırılmı¸s tipte olanlar, sıkı¸stırılmamı¸slar ve kayıpsız sıkı¸stırılmı¸slar olarak ¨u¸ce ayırabiliriz. Sıkı¸stırılmamı¸s ve kayıpsız sıkı¸stırılmı¸s imgelerde bilgi gizlemek i¸cin en ¸cok kullanılan y¨ontem, imgenin son bitlerinin mesajın bitleri ile de˘gi¸stirilmesi y¨ontemidir. Son bitlerin de˘gi¸simi genellikle imgede g¨ozle g¨or¨ulebilir bir de˘gi¸sikli˘ge sebep olmamaktadır. Ort¨u imgedeki piksellerin son bitlerinin de˘gi¸simi ile ¨ veri gizleme y¨ontemlerini her renk kanalında 1 bit yada daha fazla veri gizleyenler ve birden ¸cok renk kanalında renk kanalı sayısından daha az miktarda veri gizleyenler olarak ikiye ayırabiliriz. Bu ¸calı¸smada en ¨onemsiz bite (least significant bit-LSB) gizleme y¨ontemlerinden yer de˘gi¸stirme [1], e¸sle¸stirme [2], e¸sle¸stirmenin geli¸stirilmi¸s bir hali olan Chan’ın algoritması [3], 2/3 verimli g¨omme [4], Hamming kodlarını kullanılarak
A Study of the Information Services on Turkish High Schools
(Elsevier Science Bv, 2011) Darvish, Hamid R.
The World Wide Web went public in 1989. Since then, every organization has come to utilize web-based technologies for their various purposes. Educational institutions have implemented web technology in their contemporary curriculums. The aim of this study is to investigate five private schools in Ankara, Turkey and to unravel the impact of information technology (internet usage, information services) in their programs. The five high schools were: Ari College, TED Ankara College, Tevfik Fikret High School, METU (Middle East Technical University) College and Bilkent High School. We conducted a qualitative research on the selected high schools by observing and collecting data. Research was done from March-May 2009. We found out that internet services in high schools are not utilized to their full capacity. (C) 2011 Published by Elsevier Ltd.

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