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Yayın TL and OSL response of turquoise for dosimetric application(University of Aegean, 2010) Subedi, Bhagawan; Afouxenidis, Dimitrios; Polymeris, George S.; Tsirliganis, Nestor C.; Paraskevopoulos, Konstantinos M.; Kitis, GeorgeTurquoise is one of the amongst first gem stones used in jewelry and possessing cultural value since 2000 BC (at least). This work attempts characterize this stone scientifically using both thermally (TL) and optically stimulated luminescence (OSL) techniques. The experimental investigation included 1) the study of the natural TL and OSL signals, 2) the reproducibility of TL sensitivity over repeated irradiation and TL readout cycles, 3) dependence of sensitivity on annealing temperatures and 4) the TL and OSL dose response curves. The potential use of the TL and OSL techniques in determination of provenance, accidental dosimetry and probably to authenticity and dating purposes are then discussed.Yayın An interoperability infrastructure for distributed feed networks(2007) Wild, Fridolin; Siguroarson, Steinn E.; Sobernig, Stefan; Stahl, Christina; Soylu, Ahmet; Rebas, Vahur; Gárka, Dariusz; Danielewska-Tułecka, Anna; Tapiador, AntonioBlogs have the affordance to become an integral part of teaching and learning processes as a vehicle for knowledge management. Open, flexible systems integrating blogs provide user-friendly, personalised microlearning environments while ensuring ubiquitous access. This paper concentrates on blog interoperability in an open space for learning and collaboration. As blogging is one of the most popular web-based forms of publishing today, there is a plethora of different blogging tools, feed readers, and aggregators, enabling information dissemination, filtering, and retrieval. Several different data structure and interaction standards emerged which make integration a real challenge. This paper aims at creating distributed microlearning environments basing on networks of integrated blogs, discusses problems of such an integration along with possible solutions, and proposes an architecture for loosely-coupled blog integration. The core of this infrastructure consists of a service interface for feed management that allows learners as well as facilitators to automatically set up channel structures for feed syndication, while effectively reducing the management efforts thereof through proper system support.Yayın The survey on Near Field Communication(MDPI, 2015-06) Coşkun, Vedat; Özdenizci Köse, Büşra; Ok, KeremNear Field Communication (NFC) is an emerging short-range wireless communication technology that offers great and varied promise in services such as payment, ticketing, gaming, crowd sourcing, voting, navigation, and many others. NFC technology enables the integration of services from a wide range of applications into one single smartphone. NFC technology has emerged recently, and consequently not much academic data are available yet, although the number of academic research studies carried out in the past two years has already surpassed the total number of the prior works combined. This paper presents the concept of NFC technology in a holistic approach from different perspectives, including hardware improvement and optimization, communication essentials and standards, applications, secure elements, privacy and security, usability analysis, and ecosystem and business issues. Further research opportunities in terms of the academic and business points of view are also explored and discussed at the end of each section. This comprehensive survey will be a valuable guide for researchers and academicians, as well as for business in the NFC technology and ecosystem.Yayın A novel biometric authentication approach using electrocardiogram signals(IEEE, 2013) Gürkan, Hakan; Güz, Ümit; Yarman, Bekir Sıddık BinboğaIn this work, we present a novel biometric authentication approach based on combination of AC/DCT features, MFCC features, and QRS beat information of the ECG signals. The proposed approach is tested on a subset of 30 subjects selected from the PTB database. This subset consists of 13 healthy and 17 non-healthy subjects who have two ECG records. The proposed biometric authentication approach achieves average frame recognition rate of %97.31 on the selected subset. Our experimental results imply that the frame recognition rate of the proposed authentication approach is better than that of ACDCT and MFCC based biometric authentication systems, individually.Yayın Fingertip electrocardiogram and speech signal based biometric recognition system(Işık Üniversitesi, 2021-12-27) Güven, Gökhan; Güz, Ümit; Gürkan, Hakan; Işık Üniversitesi, Lisansüstü Eğitim Enstitüsü, Elektronik Mühendisliği Doktora ProgramıFingertip electrocardiogram and speech signal based biometric recognition system In this research work, we presented a one-dimensional CNN-based person identification system which depends on the combination of both speech and ECG modalities to improve the overall performance compared to traditional systems. The proposed method has two approach: one is to develop combination of textindependent speech and fingertip ECG fusion system, the other one is to develop a robust rejection algorithm to prevent unauthorized access to the fusion system. In addition to the system robustness, we have developed an ECG spike and inconsistent beats removing algorithm, which detect and remove the problems caused by either portable fingertip ECG devices or movements of the patients. First approach has been tested on 30, 45, 60, 75 and 90 people which were taken from LibriSpeech Corpus database and combination of both CYBHi and our private fingertip ECG database. The 3-fold cross validation test setup has been conducted while system working time was set to 10 seconds. In the first experiment, we achieved 90.22% accuracy rate for 90 people for ECG based system. For the speech based system, 97.94% accuracy rate has achieved for 90 people. For the combination of both system, 99.92% accuracy rate has been achieved. For the second approach, 90 people for ECG and Speech database were being used as genuine class, 26 people as imposter class, and after the performance evaluation in optimum rejection thresholds, 71.08% accuracy rate for imposters rejection and 71.05% accuracy rate for genuine recognition has achieved for ECG based system. For the speech based system, imposter class were 87.82% accurately rejected while genuine classes were 86.48% accurately identified. The combination of both system has achieved 91.68% accuracy for genuine identification rate whereas 96.05% accuracy for imposter rejection.Yayın A novel human identification system based on electrocardiogram features(IEEE, 2013) Gürkan, Hakan; Güz, Ümit; Yarman, Bekir Sıddık BinboğaIn this work, we present a novel biometric authentication approach based on combination of AC/DCT features, MFCC features, and QRS beat information of the ECG signals. The proposed approach is tested on a subset of 30 subjects selected from the PTB database. This subset consists of 13 healthy and 17 non-healthy subjects who have two ECG records. The proposed biometric authentication approach achieves average frame recognition rate of %97.31 on the selected subset. Our experimental results imply that the frame recognition rate of the proposed authentication approach is better than that of ACDCT and MFCC based biometric authentication systems, individually.Yayın Quarantine region scheme to mitigate spam attacks in wireless sensor networks(IEEE, 2006-08) Coşkun, Vedat; Çayırcı, Erdal; Levi, Albert; Sancak, SerdarThe Quarantine Region Scheme (QRS) is introduced to defend against spam attacks in wireless sensor networks where malicious antinodes frequently generate dummy spam messages to be relayed toward the sink. The aim of the attacker is the exhaustion of the sensor node batteries and the extra delay caused by processing the spam messages. Network-wide message authentication may solve this problem with a cost of cryptographic operations to be performed over all messages. QRS is designed to reduce this cost by applying authentication only whenever and wherever necessary. In QRS, the nodes that detect a nearby spam attack assume themselves to be in a quarantine region. This detection is performed by intermittent authentication checks. Once quarantined, a node continuously applies authentication measures until the spam attack ceases. In the QRS scheme, there is a trade-off between the resilience against spam attacks and the number of authentications. Our experiments show that, in the worst-case scenario that we considered, a not quarantined node catches 80 percent of the spam messages by authenticating only 50 percent of all messages that it processes.Yayın Kuantum sonrası kimlik doğrulama ile sıfır bilgi ispatları: zk-SNARK'lar ve zk-STARK'ların karşılaştırmalı güvenlik ve performans analizi(Işık Üniversitesi, Lisansüstü Eğitim Enstitüsü, 2025-07-01) Güner, Sabri Serhan; Çeliktaş, Barış; Işık Üniversitesi, Lisansüstü Eğitim Enstitüsü, Siber Güvenlik Yüksek Lisans Programı; Işık University, School of Graduate Studies, Master’s Program in CybersecurityParola tabanlı kimlik doğrulama yöntemleri en yaygın kullanılan güvenlik mekanizmalarından biri olsa da ciddi zaafiyetler barındırmaktadır. Ayrıca, parola altyapılarının kurulması, yönetilmesi ve güvenli bir şekilde saklanması yüksek hesaplama ve operasyonel maliyetler doğurmaktadır. Forrester Research’e göre, 1.000 kişilik bir kurumda yıllık parola sıfırlama maliyetleri yaklaşık 420.000–490.000 dolar arasında değişmektedir. Buna karşılık, sıfır bilgi ispatları (ZeroKnowledge Proofs, ZKP), hassas kimlik verilerini ifşa etmeden doğrulama yapılmasına olanak sağlayan güçlü bir kriptografik yöntemdir. 1980’lerin ortalarında temelleri atılan ZKP protokolleri, özellikle blokzinciri teknolojisi, Nesnelerin İnterneti (IoT), finans sektörü ve kimlik yönetimi gibi alanlarda kritik öneme sahiptir. Etkileşimli (Interactive Zero-Knowledge Proofs, IZKP) ve etkileşimsiz (Non-Interactive Zero-Knowledge Proofs, NIZKP) olarak ikiye ayrılan bu protokoller arasında, NIZKP çözümleri örneğin zk-SNARK ve zkSTARK, tek yönlü mesajlaşmayla doğrulama sağlayarak Ortadaki Adam (Manin-the-Middle, MitM) saldırılarına karşı daha dayanıklı bir yapı sunar. zkSNARK’lar, küçük ispat boyutları ve hızlı doğrulama süreleri sayesinde yaygınca kullanılır. zk-STARK’lar ise güvenilir kurulum gereksinimini ortadan kaldırarak daha şeffaf bir yapı ve kuantum sonrası saldırılara karşı dayanıklı bir yaklaşım sunar. ZKP, operasyonel maliyetleri azaltır, parola sıfırlama yükünü ortadan kaldırır ve veri ihlali riskini önemli ölçüde düşürür. Ayrıca, GDPR, PCIDSS ve ISO gibi düzenleyici çerçevelere uyumu kolaylaştırarak kurumlar için daha sürdürülebilir bir çözüm sunar. Sonuç olarak, bu çalışma parola tabanlı sistemlerin yerini alabilecek daha güvenli, gizliliği koruyan ve ölçeklenebilir ZKP tabanlı kimlik doğrulama tekniklerinin benimsenmesine yönelik bir perspektif sunmayı amaçlamaktadır.
