Yazar "Akkoc, Ahmet" seçeneğine göre listele

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    BLOCKBOX: Blockchain based black box designing and modeling
    (Wiley, 2024) Korkuc, Cagatay; Korkmaz, Nilay Aytas; Genc, Yasin; Akkoc, Ahmet; Afacan, Erkan; Yazgan, Erdem
    With the development of technology, data has become more accessible. The storage of critical and valuable information is getting harder and harder with the increase of cyber attacks and vulnerabilities of network and internet. The centralized storage of data causes security and privacy problems. As a remedy to these problems, blockchain has occurred. The reliability, transparency, integrity and confidentiality of the data have been increased with the blockchain technology. Blockchain maintains the immutability of the data with cryptographic hash algorithms. The data is kept in distributed structures with the consensus algorithms so that it is not lost. Projects and studies using blockchain technology have shown that data stored in centralized structures is not as reliable as data that is distributed and secured by cryptographic algorithms, smart contracts, and consensus. The data of flights, which is a critical data, has a great place in world transportation. The parameters inside the black boxes guide us on why the aircrafts have crashed: whether the responsibility belongs to the manufacturer, to the pilot, or to the aircraft technicians. In this way, the real reasons of the accident may be determined and measures can be taken for the accidents that may occur afterwards. In addition, the safe delivery of all black box data to the interested parties and its storage in a way that is immutable will not only benefit to the manufacturer's self-development by processing the data, but also help flight companies to find optimum flight data. Both the flight companies and the manufacturer will be able to read the black box data, thus the suspicion of data manipulation will be eliminated and the data will become more transparent. In this study, a system is proposed in which an aircraft's black box data can be saved safely and securely with the help of blockchain technology.
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    Digital Image Encryption Using Elliptic Curve Cryptography: A Review
    (Institute of Electrical and Electronics Engineers Inc., 2022) Habek, Muhammed; Genc, Yasin; Aytas, Nilay; Akkoc, Ahmet; Afacan, Erkan; Yazgan, Erdem
    Today, digital images are used in many different applications. They can be social media applications or critical applications such as military and medical. However, cyber attacks or privacy problems also cause serious security problems for digital images. Therefore, various methods are proposed to ensure privacy and security. The first science that comes to mind is cryptography. It is a science of encryption. Encryption methods ensure the privacy of data. Many encryption methods are used to ensure the privacy and accuracy of the digital images. This paper reviews the encryption method based on elliptic curve cryptography for digital image encryption. This review describes the parameters and security attacks that affect the performance of digital image encryption. In addition, existing studies are reviewed. Thus, this paper is about the usefulness of both design criteria to be considered for new digital image encryption methods and comparing existing studies. © 2022 IEEE.
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    ELCPAS: A new efficient lightweight certificateless conditional privacy preserving authentication scheme for IoV
    (Elsevier, 2023) Genc, Yasin; Aytas, Nilay; Akkoc, Ahmet; Afacan, Erkan; Yazgan, Erdem
    This paper proposes a new efficient certificateless conditional privacy preserving authentication (CL-CPPA) scheme named ELCPAS, which is pairing-free, energy-efficient, lightweight which uses elliptic curve cryptography (ECC) for internet of vehicles (IoV). The ELCPAS is based on the certificateless signature scheme that eliminates the key escrow problem, which is the drawback of identity-based encryption. It performs batch message verification with a very efficient method which minimizes the delays in the message verification phase. In our proposed scheme, users (vehicle etc.) do not need to communicate with central units during each message signing. Thus, the computational load and connection problems in the central units are minimized. It is also quite fast as it does not use the bilinear pairing and map-to-point operations. The performance evaluation shows that ELCPAS has efficiency in scope of computation cost, communication cost and energy consumption cost compared to other existing schemes. The security evaluation is performed according to the random oracle model (ROM) and the proposed ELCPAS scheme has been shown to be secure. In addition, it provides security requirements and it is resistant to cyber-attacks. The results of the analyses performed according to the security criteria show that it is secure.(c) 2022 Elsevier Inc. All rights reserved.
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    Elliptic Curve Cryptography for Security in Connected Vehicles
    (IEEE, 2022) Genc, Yasin; Habek, Muhammed; Aytas, Nilay; Akkoc, Ahmet; Afacan, Erkan; Yazgan, Erdem
    The concept of a connected vehicle refers to the linking of vehicles to each other and to other things. Today, developments in the Internet of Things (IoT) and 5G have made a significant contribution to connected vehicle technology. In addition to many positive contributions, connected vehicle technology also brings with it many security-related problems. In this study, a digital signature algorithm based on elliptic curve cryptography is proposed to verify the message and identity sent to the vehicles. In the proposed model, with the anonymous identification given to the vehicle by the central unit, the vehicle is prevented from being detected by other vehicles and third parties. Thus, even if the personal data produced in the vehicles is shared, it cannot be found which vehicle it belongs to.
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    Genetik Algoritma ile Genişbant Anten Tasarimi Wideband Array Design with Genetic Algorithm
    (Institute of Electrical and Electronics Engineers Inc., 2023) Dikdere, Mustafa Oner; Genc, Yasin; Korkmaz, Nilay Aytas; Akkoc, Ahmet; Afacan, Erkan; Yazgan, Erdem
    The importance of big data transfer and higher speed communication is increasing day by day in communication systems. Antennas are key objects in wireless communication systems. Antenna specifications can be designed according to wireless communication requirements. Genetic algorithms, one of the types of heuristic algorithms, play an important role in antenna design. In genetic algorithms, the proposed near-best design is given as a result to obtain the desired antenna properties. In this study, the microstrip linear antenna array was designed with the genetic algorithms, and reached a better specification than the frequency range determined by the National Communications Commission (FCC). © 2023 IEEE.
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    Higher Order Taylor and Golomb Costas Arrays
    (Institute of Electrical and Electronics Engineers Inc., 2023) Gudek, Mesut; Genc, Yasin; Korkmaz, Nilay Aytas; Akkoc, Ahmet; Afacan, Erkan; Yazgan, Erdem
    Costas arrays, which have been defined as special permutation matrices, have widespread applications in many fields. Low probability of intercept (LPI) radars are used to detect targets without being detected by hostile elements. Frequency Shift Keying is one of the modulation types used in LPI radars. Costas arrays are used to generate frequency sets for LPI radars. These frequency sets with frequency shift keying waveforms are mostly generated using methods based on finite field theory. In this study, a comprehensive search for higher order (up to 5000) variational Costas arrays have been performed with the software developed using C++ programming language. The results obtained are presented in tables. © 2023 IEEE.
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    Meningoencephalitis caused by pathogenic Sarcocystis species in a naturally infected sheep in Turkey
    (Georg Thieme Verlag Kg, 2017) Alasonyalilar-Demirer, Aylin; Kahraman, M. Mufit; Akkoc, Ahmet; Erturkuner, S. Pelin; Guzel, E. Elif; Kul, Oguz; Ipek, Volkan
    A 3-year-old sheep was examined after an acute onset of hind limb paralysis and ataxia. At necropsy, central nervous system, pulmonary and intestinal hyperaemia and ecchymoses in the aortic arch were observed. Main microscopic lesions were confined to the heart, cerebrum and cerebellum. There were a multifocal mild myocarditis and non-suppurative meningoencephalitis together with protozoal cysts in the heart and the brain. Protozoal cystic structures were observed within many of the myocardial fibers as well as in the cerebrum and cerebellum. Using light microscopy it could not be morphologically determined whether these organisms were Toxoplasma (T.) gondii or Neospora (N.) caninum. Additional diagnostic methods like immunohistochemistry and polymerase chain reaction provided differentiation of Sarcocystis from T. gondii and N. caninum. Transmission electron microscopy demonstrated characteristic features of Sarcocystis sp. as previously described. This is the first confirmed diagnosis of Sarcocystis sp. in the central nervous system of a sheep from Turkey.
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    Time-Invariant and Localized Secure Reception With Sequential Multicarrier Receive-FDA
    (IEEE-Inst Electrical Electronics Engineers Inc, 2023) Akkoc, Ahmet; Korkmaz, Nilay Aytas; Genc, Yasin; Afacan, Erkan; Yazgan, Erdem
    Secure communication in the physical layer (PHY) using frequency diverse array (FDA) antennas has become a prominent research topic in recent years due to the unique range-;angle-dependent beam pattern exhibited by FDAs. However, the time-varying and periodic nature of the FDA beam pattern prevents the achievement of a time-invariant range-angle-focused beam pattern. Consequently, a range-angle-focused beam is only achieved at a specific time instant. Therefore, it is not yet possible to focus a beam on a specific point or area in space permanently in a time-invariant manner, due to both natural propagation mechanisms and the independent time parameter. Once a wave is transmitted, time variation cannot be altered. Thus, for the FDA beam pattern, it continues to propagate over time indefinitely. However, in the case of receiving, the time parameter is under the control of the receiver. The receiver can set the time at which the incoming wave is sampled or acquired. In this study, a cross-linear array structure called the sequential multicarrier receive FDA (SMCR-FDA) and a relevant methodology are proposed to obtain a three-dimensionally localized time-invariant range-angle-focused receive beam pattern. Additionally, several novel concepts, including the cross-linear array structure, the secure reception concept, and the positional modulation (PoM) technique, are introduced.