In the modern age we live in, the internet has become an essential part of our daily life. A significant portion of our personal data is stored online and organizations run their business online. In addition, with the development of the internet, many devices such as autonomous systems, investment portfolio tools and entertainment tools in our homes and workplaces have become or are becoming intelligent. In parallel with this development, cyberattacks aimed at damaging smart systems are increasing day by day. As cyberattack methods become more sophisticated, the damage done by attackers is increasing exponentially. Traditional computer algorithms may be insufficient against these attacks in the virtual world. Therefore, artificial intelligence-based methods are needed. Reinforcement Learning (RL), a machine learning method, is used in the field of cyber security. Although RL for cyber security is a new topic in the literature, studies are carried out to predict, prevent and stop attacks. In this study; we reviewed the literature on RL's penetration testing, intrusion detection systems (IDS) and cyberattacks in cyber security.

Recent advances in machine learning, particularly with regard to deep learning, help to recognize and classify objects in medical images. In this study, endoscopy images were examined and deep learning method was used to classify healthy and polyp cells. For the proposed system, a database was created from the archives of General Surgery Department Endoscopy Unit in Kutahya Evliya Celebi Training and Research Hospital. The database contains 93 polyps and 216 normal images from 54 archive records. For image multiplexing, a total of 1236 images were obtained by rotating each image 90 degrees around its axis. While 2/3 of the randomly selected data from this obtained data was used for training the model, the rest of the data was reserved for testing. K-fold Cross Validation method was used to reduce the variability of performance results. In this study, 48 different models were created by using different activation and optimization functions to find the best classification model in deep learning. According to the experimental results, it was observed that accuracy of the models depends on the selected parameters; the best model with the accuracy rate of 91% was obtained with 64 neurons in the hidden layer, ReLU activation function and RmsProp optimization method whereas the worst model with the accuracy rate of 76% was obtained with 32 neurons in the hidden layer, Tanh activation and PmsProp optimization functions. Accordingly, classification performance of polyp images can be optimized by utilizing different activation and optimization methods during the design of deep learning models.

Ağ tabanlı Saldırı Tespit Sistemleri (NIDS), ağda bulunan tüm cihazlardan gelen trafiği izlemek ve analiz etmek için kullanılır. Makine Öğrenimi (ML) tabanlı NIDS, günümüzde bilgisayar ağlarını siber saldırılara karşı korumak için önemli araçlardan biridir. ML tabanlı NIDS'in eğitimi ve değerlendirilmesi için ağ veri özellikleri önemli bir etkiye sahiptir. Bu nedenle ML modelinin doğruluğunu ve performansını değerlendirmek için birden çok veri kümesinin ortak temel özellik kümesi içermesi gerekir. Bu çalışmada ortak NetFlow özelliklerine sahip NIDS veri setleri (NF-UNSW-NB15, NF-BoT-IoT, NF-ToN-IoT ve NF-CSE-CIC-IDS2018) kullanılarak ikili sınıflandırma yapılmıştır. Veri setlerindeki saldırı ve normal akış (saldırı yok) sınıfları dengesiz dağılım göstermektedir. Bunun üstesinden gelmek için Rastgele Alt Örnekleme yöntemi kullanılmıştır. Sınıflandırma yöntemleri olarak Rastgele Orman, K-En Yakın Komşuluk, Destek Vektör Makineleri ve Yapay Sinir Ağları algoritmaları kullanılmıştır. Farklı veri setlerinin yeniden örneklenmiş durumlarına, ML yöntemleri kullanılarak doğruluk ve performansları karşılaştırılmıştır. Bu çalışma kapsamında kullanılmış olan dört veri seti içinde en iyi sonucu Rastgele Orman algoritması vermiştir.