Thesis defense

thesis defense

Thesis defense - Şeyma Çavdar

Title: MOBILE USER DATA MINING FOR INFERRING INDIVIDUAL’S DIFFERENCES IN INFLUENCE STRATEGIES

PhD Candidate: Şeyma Çavdar

Program: Informations Systems Department 

Date: 28 August 13:00

Place: Conference Hall-01

Abstract: Owing to the widespread and ubiquitous nature of mobile technologies, a large amount of data about users including location, access and interaction behavior is currently available. These data have recently become important as it has the potential to reveal personal information and user characteristics such as personality traits. In the literature, data of mobile phone use (such as number of calls, messages) is generally collected with questionnaires or special applications and then analyzed. However, self-reported data is often difficult to collect as well as mobile call data is limited for inferring user preferences and characteristics. In addition, people increasingly use different types of mobile applications. In this thesis, personal data obtained by mobile applications will be used and analyzed with data mining techniques in order to infer personality characteristics of users (e.g. BIG5) and how they are affected by influence strategies (e.g. Cialdini’s six strategies). The results are expected to improve personalization of mobile applications and develop successful user profiles. The health domain will be selected in this thesis.

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Utku Kaplan - THE ROLE OF EXPERTISE ON CODE REVIEW FOR SECURITY: AN EYE TRACKING STUDY

Phd Candidate: Utku Kaplan

Department: Cyber Security

Date: 14 January 2019

Place:  A-212 15:30

Abstract: To improve the quality of the software and find security vulnerabilities, code review is usually performed during software development activities. The experience of software developers reviewing the code may affect the quality of the code review. This study investigates whether differences between novices and experts in the detection of vulnerabilities in the code can be identified by eye tracking. Participants’ eye movements were recorded by an eye tracker while they investigated program codes for security review. The experiment was carried out with 20 programmer participants. The results showed that experienced software developers found security vulnerabilities in a shorter time than less experienced software developers. The findings also indicated that experts are more successful in terms of finding security vulnerabilities.


Keywords: software security vulnerabilities, eye tracking, source code review

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Thesis defense - Fatih Işıktaş

Graduate School of Informatics /Information Systems

In partial fulfillment of the requirements for the degree of Master of Fatih Işıktaş will defend his thesis.

Title: APPLICATION OF SUBSPACE CLUSTERING TO SCALABLE MALWARE CLUSTERING

Date: 14th January 2019

Time: 14:00 PM

Place: A-108

Thesis Abstract : In recent years, massive proliferation of malware variants has made it necessary to employ sophisticated clustering techniques in malware analysis. Choosing an appropriate clustering approach is very important especially for rapidly and accurately mining clustering information from a large malware set with high number of attributes. In this study, we propose a clustering method that is based on subspace clustering and graph matching techniques and presents an enhanced clustering ability and scalable runtime performance for the analysis of large malware sets. Unlike traditional signature-based clustering techniques, we aimed to obtain more accurate malware clusters by comparing internal structures of malware binaries. We also integrated a subspace clustering technique in order to scale and speed up the clustering process. To be able to verify our method, we developed a system prototype that can perform the mentioned clustering processes. This prototype provides a graphical user interface which allows users to navigate over malware binaries and generated clusters for a detailed analysis. We performed clustering experiments on real malware sets by using our system prototype. The experiment results showed that using a clustering method based on comparison of internal structure of malware binaries reveals clustering outputs with a 98% accuracy. Besides, the experiment results demonstrated that our method significantly improves the runtime performance of the clustering process without degrading clustering accuracy.

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Thesis defense - Borabay Kadirdağ

Graduate School of Informatics /Cognitive Sciences

In partial fulfillment of the requirements for the degree of Master of Borabay Kadirdağ will defend his thesis.

Title: THE EFFECTS OF COGNITIVE REAPPARISAL & EXPRESSIVE SUPPRESSION ON EXAM PERFORMANCE OF UNIVERSITY STUDENTS

Date: 26th November 2018

Time: 11:30 AM

Place: A-212

Thesis Abstract : The main objective of this thesis is to examine the effect of cognitive (re-)appraisal and expressive suppression and on exam performance in Turkish university students. The study is based on the appraisal-tendency framework of Lerner and Keltner (2000) which defines cognitive appraisal as cognitive meaning making that leads to emotions, (Lerner, Li, Valdesolo, & Kassam, 2015). Expressive suppression, on the other hand, is defined as an aspect of emotional regulation where individuals mask their facial giveaways to hide their emotional states (Niedenthal, P. M., Ric, F., & Krauth-Gruber, S. 2006). Based on the cognitive reappraisal and expressive suppression abilities of the students, their affective responses (PANAS) to anxiety before and after watching a video of a stressful scene were measured to find out if there is an effect of the emotional regulation abilities to exam performances of the students. 63 students with medium-level of exam anxiety based on the Test Anxiety Questionnaire (Nist & Diehl, 1990) participated. Results of the emotional regulation abilities suggest that expressive suppression has a significant effect on exam performances. Those students who suppressed the expression of their emotions less could increase their exam scores as measured in two exams at the beginning and end of the term. The responses based on PANAS scores indicate no significant difference of emotional regulation abilities on exam performance. Keywords: emotion, exam anxiety, emotional regulation, cognitive reappraisal, expressive suppression

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Thesis defense - Burak Ünaltay

Graduate School of Informatics /Information Systems

In partial fulfillment of the requirements for the degree of Master of Burak Ünaltay will defend his thesis.

Title: A TRANSFORMATIVE EMBEDDED SOFTWARE ARCHITECTURE FOR IMAGE PROCESSING APPLICATIONS

Date: 14th November 2018

Time: 14:00 AM

Place: B-116

Thesis Abstract : Real time image processing is often subjected to very harsh constraints due to the nature of the embedded hardware it is implemented on. Embedded hardware offer very limited memory, has low processing power and required to have low power needs.These constraints however, cannot be an excuse to give up on performance, as many of the applications in this field of work are created for high end military systems, border security, medical applications and areas similar to these where performance is critical. Unfortunately, many of the image processing algorithms used in these systems are rarely developed for the limited boundaries of embedded world. As such, there is a need for a methodology where one can transform image processing algorithms that is written in high level languages (matlab, python etc..) or even in pseudo-code to the low level languages (c++, c, assembly) that is more suited for embedded world. In this study, existing software development processes that are being used for this effort will be reviewed, and an embedded software architecture will be proposed as a solution to the problems stated above.

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Thesis defense - Dilek Deniz Bilgiç

Graduate School of Informatics /Cognitive Sciences

In partial fulfillment of the requirements for the degree of Master of Dilek Deniz Bilgiç will defend his thesis.

Title: PRESCHOOL CHILDREN’S STORY CONSTRUCTION AND USE OF DEIXIS IN FICTIONAL NARRATIVES

Date: 14th November 2018

Time: 10:00 AM

Place: A-108

Thesis Abstract : The Deictic Shift theory suggests that for interpreting an utterance, deictic terms must be used and one’s deictic center needs to be shifted with respect to the speaker’s. In the present study, Turkish preschool children’s fictional narratives are studied by examining the deictic terms they use to construct the story-world context within the theory of Deictic Shift and Deictic Center. For this goal, narratives elicited by a picture-based book by 47 preschool children between ages 3;6 and 6 are explored and compared to 23 adults’ narratives. Younger children used more demonstrative deictic terms, suggesting that they are tuned to the picture-book rather than the story context. They also used temporal deictics less frequently than adults, indicating that temporal deictics develop alongside the ability of plot organization. Overall, the results show that narrative development goes hand in hand with the development of how the expressions of the real-world context are shifted to the story-world context and the development of deictic expressions to convey psychological proximity.

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Thesis defense - Eren Esgin

Title: SEQUENCE ALIGNMENT BASED PROCESS FAMILY EXTRACTION

PhD Candidate: Eren Esgin

Program: Informations Systems Department 

Date: 17 December 10:00

Place: Conference Hall-01

Abstract: Business Process Management (BPM) paradigm gains growing attention by generic process design and execution capabilities empowered by process-aware information systems. During execution of these transactional information systems, end-users leave traces in the form of event logs, which can be used as a main data source for end user behavior analysis. Process mining encompasses the techniques for automated process discovery from these event logs, conformance checking between the reference process model and process executions, as well as analyzing, predicting and enhancing the performance of business processes. With the emergence of new shared economical models and system architectures, monolithic process perspective is evolved through cross-organizational applications. While contemporary information systems provide functionality for process management within the organizations, a systematic approach to support and analyze multiorganizational processes is missing. Cross-organizational process mining supports the use of commonality and collaboration for process configuration. However, this functionality surplus creates the challenge of dealing with variability across organizations. In this study, we propose a three phased cross-organizational process mining framework in order to extract the commonalities among different organizations serving the same business values. While dominant behavior extraction phase initially derives the sequence of tasks expressing the most typical behavior within the process instances, sequence alignment phase measures the degree of similarities between the process candidates by confidenceenhanced cost functioning, and depicts the neighborhood among these alternatives in terms of process family tree. At process configuration phase, common regions that indicate a functional inheritance or abstractions in the process families are visualized at sequence alignment matrices and interpreted by new feature sets, namely identical and maximal identical pair. According to the experimental results, proposed approach presents a viable and robust cost function in incorporating the business context at process similarity measurement and clustering the process alternatives into process families. 

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Thesis defense - Fatemeh Soleymani

Graduate School of Informatics /Cognitive Sciences

In partial fulfillment of the requirements for the degree of Master of Science Fatemeh Soleymani will defend his thesis.

Title: EYE MOVEMENT CONTROL IN PERSIAN READING: A CORPUS-ANALYTIC APPROACH

Date: 06th September 2018

Time: 09:30 AM

Place: A-108

Thesis Abstract :In the Latin script languages, specifically the English language, there exist studies on the eye movements’ pattern during reading. Thus, this study was conducted in order to investigate eye movement patterns in Persian. From these sentences, taken from the Bijankhan Persian Corpus, a number of eye movement measures were analyzed. The eye movement measures were first fixation landing position, first fixation duration, gaze duration, first run fixation count, regression in count, and regression out count. The word properties in this study were word length, word frequency, word predictability, word type (opacity and transparency), and phonemes. In order to control variances of random effects which were subject, sentence, and words, the linear mixed model were utilized in the analysis. The results show that word length has an effect on first fixation landing position. Furthermore, the preferred viewing location (PVL) analysis showed that first fixations landed close to the end of short words, close to the center of medium-long words and close to the beginning of long words. These results are in line with former studies. In the first fixation duration analysis it was found that medium-long words were fixated shorter than short words. Moreover, it was found that longer gaze durations (GD) and higher first run fixation count (FRFC) corresponded with longer words. Also, a relationship between regression in count (RIC) and phonemes was obtained.

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Thesis defense - Galip Oral Okan

Graduate School of Informatics /Cyber Security

In partial fulfillment of the requirements for the degree of Master of Science Galip Oral Okan will defend his thesis.

Title: LYNXTUN

Date: 03th Sptember 2018

Time: 14:30 PM

Place: A-108

Thesis Abstract : Lynxtun is a VPN solution that allows the creation of a secure tunnel between two hosts over an insecure network. The Lynxtun Protocol transmits fully encrypted datagrams with a fixed size and at a fixed interval using UDP/IP. Our custom authenticated encryption scheme uses the AES-256 block cipher and modified version of GCM mode in order to decrypt and authenticate datagrams efficiently. It ensures traffic flow confidentiality by maintaining a constant bitrate that does not depend on underlying communication. In this sense, it provides unobservable communication. This constitutes a difficult engineering problem. The protocol design allows implementations to fulfill this requirement. We analyze factors that influence realtime behavior and propose solutions to mitigate this. We developed a full implementation for the GNU/Linux operating system in the C programming language. Our implementation succeeds in performing dispatch operations at the correct time, with a tolerance on the order of microseconds, as we have verified empirically.

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Thesis defense - Faruk Büyüktekin

Graduate School of Informatics /Cognitive Sciences

In partial fulfillment of the requirements for the degree of Master of Science Faruk Büyüktekin will defend his thesis.

Title: MULTI-MODAL REFERENCE RESOLUTION IN SITUATED DIALOGUE THROUGH LINGUISTIC AND EXTRA-LINGUISTIC INFORMATION

Date: 31st August 2018

Time: 10:00 AM

Place: A-108

Thesis Abstract : This thesis investigates the effect of extra-linguistic information incorporated into linguistic information on multimodal reference resolution in Turkish. Identifying reference relations such as anaphora and coreference within texts is quite critical in the fields of natural language processing and human computer interaction since such applications require interpreting the text. Previous research on reference resolution has employed mostly hand-crafted rule-based approaches. However, due to the success of machine learning algorithms, there has been a shift towards corpus-based approaches. Therefore, investigations of reference resolution within real world situations have received a great deal of attention. In line with these developments, this study focuses on a Turkish corpus which is based on the dialogues of two participants collaboratively solving a Tangram puzzle. The corpus includes eye gaze and mouse operations of the participants along with their utterances. This study offers a model that identifies the referent (the object) of a referring expression in the real world by taking eye gaze and operations on puzzle pieces into account. The model is built making use of machine learning algorithms. The model also examines which type of extra linguistic information is more successful in determining the referents of pronouns, non-pronouns and both within a machine learning based-approach.

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