Çakar, Tuna
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Çakar T.
Tuna Çakar
Çakar,Tuna
Çakar Tuna
Çakar, T.
Tuna Çakar
Çakar,Tuna
Çakar Tuna
Çakar, T.
Job Title
Email Address
cakart@mef.edu.tr
Main Affiliation
02.02. Department of Computer Engineering
Status
Current Staff
Website
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Sustainable Development Goals
1NO POVERTY
1
Research Products
2ZERO HUNGER
2
Research Products
3GOOD HEALTH AND WELL-BEING
5
Research Products
4QUALITY EDUCATION
1
Research Products
5GENDER EQUALITY
0
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6CLEAN WATER AND SANITATION
0
Research Products
7AFFORDABLE AND CLEAN ENERGY
0
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8DECENT WORK AND ECONOMIC GROWTH
5
Research Products
9INDUSTRY, INNOVATION AND INFRASTRUCTURE
1
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10REDUCED INEQUALITIES
0
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11SUSTAINABLE CITIES AND COMMUNITIES
2
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12RESPONSIBLE CONSUMPTION AND PRODUCTION
1
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13CLIMATE ACTION
0
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14LIFE BELOW WATER
0
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15LIFE ON LAND
2
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16PEACE, JUSTICE AND STRONG INSTITUTIONS
2
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17PARTNERSHIPS FOR THE GOALS
1
Research Products
This researcher does not have a Scopus ID.
This researcher does not have a WoS ID.
Scholarly Output
119
Articles
17
Views / Downloads
20718/248158
Supervised MSc Theses
18
Supervised PhD Theses
0
WoS Citation Count
80
Scopus Citation Count
152
Patents
0
Projects
6
WoS Citations per Publication
0.67
Scopus Citations per Publication
1.28
Open Access Source
49
Supervised Theses
18
| Journal | Count |
|---|---|
| 32nd IEEE Signal Processing and Communications Applications Conference (SIU) -- MAY 15-18, 2024 -- Tarsus Univ Campus, Mersin, TURKEY | 9 |
| 2022 7th International Conference on Computer Science and Engineering (UBMK) | 6 |
| 2023 31st Signal Processing and Communications Applications Conference (SIU) | 6 |
| International Conference on Computer Science and Engineering, UBMK | 5 |
| 2023 4th International Informatics and Software Engineering Conference (IISEC) | 5 |
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119 results
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Now showing 1 - 10 of 119
Conference Object Predicting Animal Behaviours: Physical and Behavioural Classification Of Dog Walking Levels(IEEE, 2022) Ozen, Guris; Karan, Baris; Çakar, TunaMethods of predicting canine behaviour is an area covered by canine behaviour experts. This study aims to predict the behaviour of dogs during walking based on available information about dogs. In this data-driven project based on up-to-date company data, the problem of predicting dog behaviour was addressed in two different ways. First, it is aimed to create a supervised classification model. Within the scope of this study, improvements were made to various classification algorithms. The results were analyzed in different axes. Secondly, it is aimed to create a new parameter that predicts dog walking difficulties by formulating the parameters.Conference Object A Predictive Model for Bounced Check Risk Using Machine Learning(Institute of Electrical and Electronics Engineers Inc., 2025) Kaya K.; Sayar A.; Memis E.C.; Ozlem S.; Ertugrul S.; Cakar T.; Sayar, Alperen; Cakar, Tuna; Ertugrul, Seyit; Ozlem, Sirin; Memis, Emir Cetin; Kaya, KeremBounced checks result in direct monetary losses. Traditional rule-based systems cannot adapt to new patterns and lack flexibility. In this study, we used a large and imbalanced check dataset with customer profiles, credit limits, and historical check outcomes. We applied feature engineering emphasizing time-based transaction patterns, extensive clustering, anomaly detection, and inflation adjustment. We trained six models each for two datasets, which are undersampled to handle class imbalance: Logistic Regression, Random Forest, XGBoost, LightGBM, Extra Trees, and CatBoost. The best performing model, CatBoost, achieved macro F1 scores of 88.5 percent on individual checks dataset with a gross sunk rate of 4.92 percent, and 91.7 percent on corporate checks dataset with a gross sunk rate of 4.28 percent. These results show the model can identify checks most likely to bounce before granting and maintain a low gross sunk rate overall. This study presents a data-driven machine learning solution that enables financial companies to predict and prevent bounced checks before they occur. © 2025 IEEE.yl-bitirme-projesi.listelement.badge Trangling Weratedogs Twitter Data To Create Interesting and Trustworthy Explosatory/Predictive Anaylses and Visulation Using Different Machine Learning Algorithms(MEF Üniversitesi, Fen Bilimleri Enstitüsü, 2018) Arı, Esra; Çakar, TunaSocial media usage has rapidly grown in recent years and knowledge in these environments increased due to this expansion. Therefore, doing exploratory and predictive analysis from intensive data of social media became so popular. However, almost all of the large datasets obtained are uncleaned / raw data. Therefore, the assessing and cleaning of the data is at least as important as the exploratory and predictive analysis. The open source WeRateDogs twitter account tweets have been gathered, assessed, cleaned, analyzed and predicted for this thesis. As a result of the study, it was understood that the most important and most time-consuming part of the predictive data analysis is the data gathering and cleaning. As a result of this project, probability of dog’s breed whether retriever or not is predicted from the tweet’s text body. 24 points increase (%34 change) in accuracy values has been achieved by doing oversampling in the data sets which contain low event observation. At the same time, the decision tree, logistic regression and random forest algorithms are compared and it is shown that the random forest's model performance is better than the others. The algorithm works 13 points better than logistic regression, 21 points better than decision tree.Conference Object Citation - Scopus: 5High-Performance Real-Time Data Processing: Managing Data Using Debezium, Postgres, Kafka, and Redis(IEEE, 2023) Çakar, Tuna; Ertuğrul, Seyit; Arslan, Şuayip; Sayar, Alperen; Akçay, AhmetThis research focuses on monitoring and transferring logs of operations performed on a relational database, specifically PostgreSQL, in real-time using an event-driven approach. The logs generated from database operations are transferred using Apache Kafka, an open-source message queuing system, and Debezium running on Kafka, to Redis, a non-relational (No-SQL) key-value database. Time-consuming query operations and read operations are performed on Redis, which operates on memory (in-memory), instead of on the primary database, PostgreSQL. This approach has significantly improved query execution performance, data processing time, and backend service performance. The study showcases the practical application of an event-driven approach using Debezium, Kafka, Redis, and relational databases for real-time data processing and querying.Master Thesis EAFT: Evolutionary algorithms for GCC flag tuning(MEF Üniversitesi, 2023) Tağtekin, Burak; Çakar, TunaThe runtime of written codes is a matter of great importance, especially for code that is compiled once and executed multiple times. It is very important for developers to ensure that the resources required by a code are used as efficiently as possible, and that the runtime is as low as possible. Developers who use compilers such as GCC or LLVM to compile and run code written in C or C++ can optimize their code manually and, with certain optimization pointers, are able to make it run faster. This will provide the shorter runtime, but completıng this manual optimization is within the abilities of every developer since determining the right combination from more than 200 flags requires significant expertise. Many studies have tackled this issue. In this study, Evolutionary Algorithms for GCC Flag Tuning (EAFT) have been developed as a solution to this problem. This Autotuner, which is completely open-source, runs the code provided by the end user according to the specifications also selected by the end user, and searches for the most suitable optimization markers. For the code to be given In line with this study, which specifically addresses the end user, the user can input the code path directly from the Terminal, as well as specify the selection method and the crossover to be used. These choices can be made without the need to alter the code. The genetic algorithm and particle swarm optimization to be used is also presented to the user in EAFT, and unlike in other studies, genetic algorithm contain not one but several models.Master Thesis Comparing the effectiveness of graph neural networks and machine learning algorithms for fNIRS-based neuromarketing research(MEF Üniversitesi, 2024) Güngör, Atakan; Çakar, TunaFonksiyonel yakın kızılötesi spektroskopinin (fNIRS) maliyet ve taşınabilirlik açısından diğer beyin görüntüleme yöntemlerine göre bazı avantajları vardır. Bu nedenle nöropazarlama alanında kullanımı gittikçe artmaktadır. Ancak fNIRS, sağladığı avantajların yanında bazı zorlukları da beraberinde getirmektedir. Çok kanallı ölçüm ve yüksek zamansal çözünürlük gibi özellikler nedeniyle fNIRS verilerinin doğası karmaşık ve çok boyutludur [7]. Nöropazarlama araştırmacıları, bu zorlukların üstesinden gelebilmek için makine öğrenimi algoritmalarından yararlanmıştır. Bu çalışmalar incelendiğinde başarılı sonuçların ortaya çıktığı görülmüştür. Makine öğrenimi, nöropazarlama araştırmacılarının yanı sıra çizge üzerinde çalışan araştırmacıları da etkilemiştir. Böylece yapay sinir ağlarının çizge veri yapılarına uygulanmasına izin veren çizge sinir ağları ortaya çıkmıştır. Beynin fonksiyonel bağlantılar kullanılarak çizge yapısı şeklinde modellenebilmesi [14] ve fNIRS'in yüksek zamansal çözünürlüğü sayesinde [7], çizge sinir ağları ile fNIRS'in birlikte kullanıldığı nörogörüntüleme çalışmaları mevcuttur. Ancak başarılı sonuçlara rağmen bu kombinasyona yer veren nöropazarlama araştırmasına rastlanmamıştır. Bu nedenle bu çalışmada, çizge sinir ağlarının fNIRS temelli nöropazarlama alanındaki performansı incelenmiş ve bu bağlamda başarılı sonuçlar verdiği görülen makine öğrenimi algoritmaları ile karşılaştırılması yapılmıştır. Karşılaştırma için, markalara yönelik algıları belirlemek amacıyla yürütülen bir nöropazarlama deneyinin fNIRS ölçümleri kullanılmıştır. Deneyde, tüketicilerden marka logosuyla birlikte gösterilen sıfatın markaya uygun olup olmadığına dair karar vermeleri (evet/hayır) istenmiştir. Elde edilen ölçümler temizlenerek veri seti elde edilmiştir. İlk olarak bu veri setine gözetimli makine öğrenimi yaklaşımı uygulanmıştır. Veri seti birkaç veri ön işleme aşamasından geçirildikten sonra üzerinde çeşitli algoritmalar eğitilmiştir. Bunlar, K-Nearest Neighbors, Support Vector Machines, Random Forest, Naive Bayes ve XGBoost algoritmalarıdır. Sonrasında ise diğerlerine göre daha başarılı olan algoritmalardan, biri soft voting diğeri hard voting olmak üzere iki farklı voting classifier oluşturulmuştur. Makine öğrenimi yaklaşımı tamamlandıktan sonra çizge sinir ağları yaklaşımına geçilmiştir. fNIRS aracılığı ile elde edilen veriler, beyindeki fonksiyonel bağlantılar kullanılarak çizge yapısına dönüştürülmüştür. Fonksiyonel bağlantıların hesaplanmasında Pearson korelasyon katsayısı kullanılmıştır. Katılımcıların her denemesi için bir çizge oluşturulduğundan ve her çizgenin etiketi (evet/hayır) bulunduğundan, çizge seviyesinde sınıflandırma yapılmıştır. Çizgelerin sınıflandırılması için, oluşturulan çizgeler, çizge sinir ağları mimarilerine girdi olarak verilmiştir. Çalışmada kullanılan mimariler, Graph Convolutional Network, Graph Attention Network ve Graph Isomorphism Network'ten oluşmaktadır. Son olarak, bu mimarilerin bir araya getirilmesiyle bir soft voting classifier oluşturulmuştur. Tüm yöntemlerin test accuracy değerleri hesaplanmış ve bu değerlere güven aralıkları eklenmiştir. Karşılaştırma sonuçları, genel olarak makine öğrenimi algoritmalarının çizge sinir ağlarından daha iyi performans verdiğini göstermiştir. Ek olarak, topluluk öğrenimine dayalı makine öğrenimi modelleri en iyi skorlara sahiptir.Conference Object Evaluating Electrophysiological Responses Due To Identity Judgments(Ieee, 2024) Çakar, Tuna; Hohenberger, AnnetteThis study was conducted to explore how the brain processes decisions about identity, employing event-related potentials (ERPs) as a measure. The aim was to ascertain if the EEG/ERP technique could be used to monitor the cognitive processing of identity judgments as they happen. The investigation focused on comparing two groups of statements: those that used the concept of 'same' and those that used 'different'. The researchers hypothesized that there would be notable differences in the ERPs, particularly around the 400-millisecond mark, correlating with the reaction time disparities observed behaviorally. The ERP data revealed that the 'different' statements generated a unique N400 response when contrasted with the 'same' statements, implying that the participants' cognitive responses to these two types of judgments were not the same.Conference Object Citation - Scopus: 2Ssqem: Semi-Supervised Quantum Error Mitigation(IEEE, 2022) Sayar, Alperen; Arslan Suayb S.; Çakar Tuna; Arslan, Suayb S.; Cakar, TunaOne of the fundamental obstacles for quantum computation (especially in noisy intermediate-scale quantum (NISQ) era) to be a near-term reality is the manufacturing gate/measurement technologies that make the system state quite fragile due to decoherence. As the world we live in is quite far away from the ideal, complex particle-level material imperfections due to interactions with the environment are an inevitable part of the computation process. Hence keeping the accurate state of the particles involved in the computation becomes almost impossible. In this study, we posit that any physical quantum computer sys-tem manifests more multiple error source processes as the number of qubits as well as depth of the circuit increase. Accordingly, we propose a semi-supervised quantum error mitigation technique consisting of two separate stages each based on an unsupervised and a supervised machine learning model, respectively. The proposed scheme initially learns the error types/processes and then compensates the error due to data processing and the projective measurement all in the computational basis. © 2022 IEEE.Article Performing Disc Personal Inventory Analysis in Job Postings Using Artificial Intelligence Methods(Data science and applications, 2023) Sayar, Alperen; Yıldız, Ahmet; Çakar, Tuna; Şengüloğlu, Dilara; Ertuğrul, SeyitOne of the application fields of DISC selfevaluation analysis was introduced to predict people's performance and orientation in their working life. Each letter in the word DISC represents an essential personal characteristic, dividing the profiles of people in business life into four essential parts. In the current study, DISC analysis is conducted on job postings to match the person with the job posting. The current study was based on the analysis of 3 different datasets with job postings in English, Turkish and Romanian prepared by using web scraping methods and then labeled in accordance with DISC criteria. Several different machine learning algorithms have been performed on the DISC analysis outputs, and they reached the best results with accuracy values of around over 96% on the English dataset, around over 95% on the Turkish dataset, and around over 96% on the Romanian dataset, for both D, I, S, C models.Master Thesis Customer churn prediction for a personal care product retail chain operating in Turkey(MEF Üniversitesi, 2024) Işık, Ercan; Çakar, TunaMüşteri kaybının nedenlerini ve buna yol açan müşteri davranışlarını anlamak, ayrıca müşterinin bir sektöre veya şirkete olan sadakatini tahmin edebilmek, mevcut müşterileri elde tutmada ve yeni müşterilere ulaşmak için yapılan pazarlama ve reklam maliyetlerinden kaynaklanan gelir kaybını önlemede büyük avantaj sağlar. Bu çalışmada, Türkiye'de faaliyet gösteren bir kişisel bakım ürünleri perakende zincirine ait 29 aylık veri kullanılmış; veri setindeki dengesiz dağılım ve müşteri olmayan girişler nedeniyle aşırı örnekleme ve sentetik örnekleme yöntemleri uygulanmıştır. Model geliştirme aşamasında Lojistik Regresyon, Karar Ağacı, K-En Yakın Komşu, Rassal Orman, Ekstra Ağaç Sınıflandırıcı, MLP (Çok Katmanlı Algılayıcı) Sınıflandırıcı uygulanmış ve doğruluk, geri çağırma, F1 skoru, kesinlik ve karmaşıklık matrisi gibi metrikler kullanılarak performansları değerlendirilmiştir. Bu karşılaştırmalar sonucunda, Rassal Orman ve MLP Sınıflandırıcı modellerinin bu veri seti için en iyi performansı gösterdiği gözlemlenmiş; Ekstra Ağaç Sınıflandırıcı ve Karar Ağacı gibi diğer ağaç tabanlı algoritmaların ise biraz daha düşük fakat karşılaştırılabilir performans sağladığı tespit edilmiştir.
