Browsing by Author "Kocak, Taskin"

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A battery-friendly data acquisition model for vehicular speed estimation
(PERGAMON-ELSEVIER SCIENCE LTDTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND, 2016) Kaya, Sevgi; Kilic, Necati; Kocak, Taskin; Gungor, Cagri; AGÜ, Mühendislik Fakültesi, Bilgisayar Mühendisliği Bölümü; Gungor, Cagri
Modeling traffic flow and gathering accurate traffic congestion information are two challenging problems in smart transportation systems. Most of the traffic flow models and velocity estimation methodologies that have been proposed so far gather the data from GPS-equipped smart phones and extract the flow model based on GPS sampling. However, these approaches tend to fail in real life scenarios due to the insufficient vehicle data and unpredictable dynamics of the flow. Furthermore, utilization of GPS sensor leads to a battery drainage and hence reduces the overall system performance. In this paper, we propose a new battery-friendly data acquisition model to obtain the raw data. We then evaluate our model under various traffic conditions to determine its feasibility in vehicle speed estimation. The proposed model results in 88% location accuracy whereas it reduces the battery consumption by half. (C) 2016 Elsevier Ltd. All rights reserved.
Credit Risk Analysis based on Hybrid Classification: Case Studies on German and Turkish Credit Datasets
(IEEE, 2018) Cetiner, Erkan; Kocak, Taskin; Güngör, Vehbi Çağrı; 0000-0003-0803-8372; AGÜ, Mühendislik Fakültesi, Bilgisayar Mühendisliği Bölümü; Güngör, Vehbi Çağrı
— Kredi risk analizi, karar verme süreçleri açısından finans sektöründe önemli bir rol oynamaktadır. Bankalar ve finansal kuruluşlar, müşterilerinden büyük ölçeklerde ham veri toplamaktadırlar. Veri madenciliği teknikleri, bu ham veri içerisinden kullanışlı bilgiler edinmek amacıyla kullanılabilir. Destek-vektörleri, yapay sinir ağları ve bayesian yaklaşımı bu alanda hali hazırda kullanılan sınıflandırma yöntemleridir. Bu çalışmada, farklı tekil sınıflandırma yöntemlerinin bir araya getirilerek hibrid bir yaklaşımla, sınıflandırma sonuçlarının doğruluğunun arttırılması hedeflenmiştir. Farklı kombinasyonlar ayrıca sınıflandırma yetkinliği açısından performans karşılaştırılmasına tabi tutulmuştur. Hem Alman kredi veriseti hem de ulusal bir bankadan alınan veriseti üzerinde ilgili yaklaşım çalıştırılmış ve yöntemin genelleştirilebilme özelliğinin görülmesi de amaçlanmıştır. Deney sonuçları, özellik seçiminin sınıflandırma başarımı ve hesaplama zamanı açısından çok önemli olduğunu, hibrid yaklaşımın tekil sınıflandırma yöntemlerine göre sınıflandırma doğruluğu açısından daha iyi sonuçlar verdiğini ve son olarak radial-basis fonksiyonu ile birlikte kullanıldığında destek-karar vektörlerinin hem tekil hem hibrid yaklaşımlar içerisinde en iyi sınıflandırma başarımına sahip olduğunu göstermiştir.
Evaluation of hybrid classification approaches: Case studies on credit datasets
(SPRINGER, 2018) Cetiner, Erkan; Gungor, Vehbi Cagri; Kocak, Taskin; 0000-0003-0803-8372; AGÜ, Mühendislik Fakültesi, Bilgisayar Mühendisliği Bölümü; Gungor, Vehbi Cagri
Hybrid classification approaches on credit domain are widely used to obtain valuable information about customer behaviours. Single classification algorithms such as neural networks, support vector machines and regression analysis have been used since years on related area. In this paper, we propose hybrid classification approaches, which try to combine several classifiers and ensemble learners to boost accuracy on classification results. We worked with two credit datasets, German dataset which is a public dataset and a Turkish Corporate Bank dataset. The goal of using such diverse datasets is to search for generalization ability of proposed model. Results show that feature selection plays a vital role on classification accuracy, hybrid approaches which shaped with ensemble learners outperform single classification techniques and hybrid approaches which consists SVM has better accuracy performance than other hybrid approaches.
Operator User Management System Based on the TMF615 Standard
(SPRINGERONE NEW YORK PLAZA, SUITE 4600 , NEW YORK, NY 10004, UNITED STATES, 2016) Yigit, Melike; Macit, Muhammed; Gungor, V. Cagri; Kocak, Taskin; Ozhan, Oguz; AGÜ, Mühendislik Fakültesi, Bilgisayar Mühendisliği Bölümü; Gungor, V. Cagri
Multi-vendor telecommunications networks in a typical service provider environment are managed using multiple proprietary user management systems (UMS), supplied by the operational support system (OSS) vendors. The management of a typical service provider includes communications solutions put into place between the global UMS and the local UMS. Nowadays, in service provider environments OSSs exist that use multi-vendor communications' protocols. In the telecommunications sector, the centralized management of all these different OSSs can cause serious problems for the network operation. In this respect, there is an urgent need for a standardized and centralized provisioning and auditing mechanism for the operators and their entitlements that work on these management systems. To address this need and to provide efficient operations among different service provider network components, this paper outlines the design and development of a TMF615 (Tele Management Forum) standard-based, common communication platform. In this respect, the proposed approach includes a common interface to address communication problems in multi-vendor, service provider environments. The interface and performance evaluations developed are some of the first solutions in this field, and the resulting solutions are converted into a commercial product with a high added value. In this regard, our proposed approach makes an important contribution to scientific literature and commercial applications. The realization of the proposed TMF615 standard-based interface enables the efficient and easy integration of existing and new OSSs of the service providers. In this way, a standardized interface is offered, along with a common communications platform adequate for all different systems. The vendors are thereby only responsible for application development based on specifications, and a standardized communications process is introduced for all related systems. This significantly facilitates the management of service providers, system performance is improved, and a massive cost reduction is provided at the same time. Consequently, the efficient management of network components is provided using a common standardized interface. In this respect, we aim to explain the TMF615 specifications; the evolution of UMS, OSSs and TMF615 with centralized UMS, as well as the implementation and performance evaluation of the TMF615 protocol are all explained in this paper.
Physical layer authentication for extending battery life
(ELSEVIERRADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS, 2021) Ayyildiz, Cem; Cetin, Ramazan; Khodzhaev, Zulfidin; Kocak, Taskin; Soyak, Ece Gelal; Gungor, V. Cagri; Kurt, Gunes Karabulut; AGÜ, Mühendislik Fakültesi, Bilgisayar Mühendisliği Bölümü; Gungor, V. Cagri
Increasing population density in cities, and the increasing demand for efficiency in resource usage call for architectures enabling smart cities, such as the Internet of Things (IoT). In most such scenarios, the data generated by IoT sensors is not confidential, but its integrity is critical. Data integrity can be achieved by establishing certification mechanisms that provide cryptographic message authentication protocols; however, this requires relatively expensive components for storing and processing the encryption key on the sensor and consumes more power while processing and transmitting data, which leads to the renunciation of security issues in cost sensitive deployments. In this paper, we propose a security solution that provides data integrity without draining the batteries of IoT sensors. Our solution consists of, (i) differentiating legitimate sensors by taking advantage of their impurities formed during the manufacturing process of the transceiver components, and (ii) eliminating the complex components that carry out cryptography as well as the redundant packet header fields, thereby yielding power savings. The testbed implementation of the proposed solution yields power measurement results providing an estimate of 2.52 times improvement in battery life without compromising the integrity of communications in the system, in addition to offering an increase in spectral efficiency and a decrease in the overall IoT device cost.
Quality-of-service differentiation in single-path and multi-path routing for wireless sensor network-based smart grid applications
(ELSEVIER, 2014) Sahin, Dilan; Gungor, Vehbi Cagri; Kocak, Taskin; Tuna, Gurkan; 0000-0003-0803-8372; AGÜ, Mühendislik Fakültesi, Bilgisayar Mühendisliği Bölümü; Gungor, Vehbi Cagri
Electrical grid is one of the most important infrastructure of the modern nation. However, power grid has been aged over 100 years and prone to major failures. The imbalance between power demand and supply, the equipment failures and the lack of comprehensive monitoring and control capabilities are other important signs to take incremental steps for switching to a smarter power grid with effective communication, automation and monitoring skills. This new concept is named as smart grid, which is a modern power grid system with advanced communication, monitoring, sensing and control capabilities. Wireless sensor network (WSN) concept places an important role in this modernization process of the power grid with its efficient and low-cost deployment characteristics. However, harsh and complex smart grid environmental conditions, dynamic topology changes, connectivity problems, interference and fading may pose some challenges for the communication performance of WSN technology. For this objective, in this paper, the use of multi-path and single-path QoS-aware routing algorithms under harsh SG environmental conditions is investigated in order to evaluate their service differentiation capabilities in reliability and timeliness domains. In this regard, this study is an important step towards developing novel routing protocols specifically designed for smart grid environments.
Routing protocol design guidelines for smart grid environments
(ELSEVIER, 2014) Temel, Samil; Gungor, Vehbi Cagri; Kocak, Taskin; 0000-0003-0803-8372; AGÜ, Mühendislik Fakültesi, Bilgisayar Mühendisliği Bölümü; Gungor, Vehbi Cagri
The evaluation of the current electric power grid with novel communication facilities is one of the most challenging and exciting issues of the 21st century. The modern grid technology is called the smart grid in the sense that it utilizes digital communication technologies to monitor and control the grid environments, which ultimately require novel communication techniques to be adapted to the system. Wireless sensor networks (WSN) have recently been considered as a cost-effective technology for the realization of reliable remote monitoring systems for smart grid. However, problems such as noise, interference and fading in smart grid environments, make reliable and energy-efficient multi-hop routing a difficult task for WSNs in smart grid. Our main goal is to describe advantages and applications of WSNs for smart grid and motivate the research community to further investigate this promising research area. In this study we have investigated and experimented some of the well-known on-demand, table-driven and QoS-aware routing protocols, in terms of packet delivery ratio, end-to-end delay, and energy consumption to show the advantages and disadvantages of each routing protocol type in different smart grid spectrum environments. The environmental characteristics which are based on real-world field tests are injected into ns-2 Network Simulator and the performance of four different multihop routing protocols is investigated. Also, we have shown that traditional multi-hop routing protocols cannot deliver adequate performance on smart grid environments. Hence, based on our simulation results, we present some guidelines on how to design routing protocols specifically for smart grid environments
Structure Health Monitoring Using Wireless Sensor Networks on Structural Elements (vol 82, pg 68, 2019)
(ELSEVIER, RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS, 2020) Ayyildiz, Cem; Erdem, H. Emre; Dirikgil, Tamer; Dugenci, Oguz; Kocak, Taskin; Altun, Fatih; Gungor, V. Cagri; AGÜ, Mühendislik Fakültesi, Bilgisayar Mühendisliği Bölümü
This paper presents a system that monitors the health of structural elements in Reinforced Concrete (RC), concrete elements and/or masonry buildings and warn the authorities in case of physical damage formation. Such rapid and reliable detection of impairments enables the development of better risk management strategies to prevent casualties in case of earthquake and floods. Piezoelectric (PZT) sensors with lead zirconate titanate material are the preferred sensor type for fracture detection. The developed sensor mote hardware triggers the PZT sensors and collects the responses they gather from the structural elements. It also sends the collected data to a data center for further processing and analysis in an energy-efficient manner utilizing low-power wireless communication technologies. The access and the analysis of the collected data can be remotely performed via a web interface. Performance results show that the fractures serious enough to cause structural problems can be successfully detected with the developed system.