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Conference Object An Rfid Based Location Finding and Tracking With Guidance(Ieee, 2008) Oktem, Rusen; Aydin, Elif Uray; Cagiltay, Nergiz ErcilThis paper tackles an RFID based location finding and tracking system. The system is an integral part of a navigation aid being developed for guiding visually disabled people in a store. The aid is composed of a portable hardware interface unit, a standalone RFID unit, and a central processing unit. The units interact via wireless communication to locate the position of the user in a known indoor environment and tracking his/her movement. An active RFID tag helps to estimate the location of a user and the user is guided to follow a route accordingly, via a tactile compass. The system uses RF signal strengths and is based on Bayes Decision Theory. Initial simulation results with the system prove promising for location finding and tracking, especially when the tracked person is guided by a system.Conference Object A Segmentation Algorithm for Foreground/Background Extraction(Ieee, 2006) Oktem, Rusen; Guldogan, Esin; Gabbouj, MoncefThis paper describes a three-pass segmentation algorithm followed by a foreground/background extraction rule. Being imperfect, the basic objective of the proposed segmentation is to enable the extraction of objects that may be of main interest to the user, and the background. The formed segments are assigned points, according to the location of their center of mass and bounding box coordinates, and spatial dispersion. Each segment is labelled as foreground or background in compliance with the grade point they get.Article Citation - Scopus: 2Regularization-Based Error Concealment in Jpeg 2000 Coding Scheme(Ieee-inst Electrical Electronics Engineers inc, 2007) Oktem, RusenThis letter offers a solution to bit-error recovery for high-frequency subbands at high decomposition levels of JPEG 2000 bitstreams, with a novel perspective. Being inspired by the regularization approach, corrupted coefficients are estimated by imposing a smoothness constraint on the gradient of the reconstructed data. The approach can be generalized to other compression engines as well. Experimental results show that the proposed method achieves the best reported results so far, with up to 6 dB of PSNR improvement. The method does not require any parameter tuning, however, it does require numerical minimization.Article Citation - WoS: 40Citation - Scopus: 66Locally Adaptive Dct Filtering for Signal-Dependent Noise Removal(Springer, 2007) Oktem, Rusen; Egiazarian, Karen; Lukin, Vladimir V.; Ponomarenko, Nikolay N.; Tsymbal, Oleg V.This work addresses the problem of signal- dependent noise removal in images. An adaptive nonlinear filtering approach in the orthogonal transform domain is proposed and analyzed for several typical noise environments in the DCT domain. Being applied locally, that is, within a window of small support, DCT is expected to approximate the Karhunen- Loeve decorrelating transform, which enables effective suppression of noise components. The detail preservation ability of the filter allowing not to destroy any useful content in images is especially emphasized and considered. A local adaptive DCT filtering for the two cases, when signal-dependent noise can be and cannot be mapped into additive uncorrelated noise with homomorphic transform, is formulated. Although the main issue is signal-dependent and pure multiplicative noise, the proposed filtering approach is also found to be competing with the state-of-the-art methods on pure additive noise corrupted images.Conference Object An Indoor Navigation Aid Designed for Visually Impaired People(Ieee, 2008) Oktem, Rusen; Aydin, Elif; Cagiltay, Nergiz ErcilThis work introduces the hardware architecture and general principles of a portable indoor navigation system for guiding visually impaired people. It operates through wireless communication between a compact hardware interface unit carried by the user, a central processing unit and an active RFID unit. The RFID unit collects signals as regard to the position of the user, the central system processes those signals to estimate the position of the user and proposes a route and direction for the user to follow, whereas hardware interface unit provides interaction. The orienteering of the user is obtained by a tactile compass.Conference Object Citation - WoS: 1Gezgin & Gezgin-2(Ieee Computer Soc, 2006) Ismailoglu, N.; Benderli, O.; Yesil, S.; Sever, R.; Okcan, B.; Sengul, O.; Oktem, RusenGEZGIN and GEZGIN-2 are real-time multispectral image processing subsystems developedfor BILSAT-1 and RASAT satellites respectively, the first two earth observing small satellites of Turkey. Main functionality of these subsystems is to compress in real-time multi-spectral images received concurrently from imagers, using JPEG2000 Image Compression algorithm. The compression features are controlled through user-supplied parameters uploaded in-orbit, so that the compression rate could be adapted to bandwidth, image quality and other mission requirements. GEZGIN employs both reconfigurable hardware and a DSP processor for image processing, where as the more advanced GEZGIN-2 contains full integration of the JPEG2000 processing path plus other image pre-processing features on reconfigurable hardware, hence offering increased performance and full re-configurability in orbit. Both systems demonstrate space-tailored architectures for implementing image processing functions where adaptability becomes the crucial issue determining robustness, flexibility and survivability of the system.Article Citation - WoS: 28Citation - Scopus: 38Requirements for Remote Rf Laboratory Applications: an Educators' Perspective(Ieee-inst Electrical Electronics Engineers inc, 2009) Cagiltay, Nergiz Ercil; Aydin, Elif; Oktem, Rusen; Kara, Ali; Alexandru, Marian; Reiner, BodoThis paper discusses the results of a study of the requirements for developing a remote RF laboratory. This study draws on the perspectives of educators in university electrical engineering departments and in technical colleges, on the teaching of the radio frequency (RF) domain. The study investigates how these educators would like the technical content of a state of the art RF laboratory to be designed. As far as the authors know, no publication exists in the literature that investigates the requirements and needs of remote laboratories in that particular field. The outcomes of this work are expected to guide remote laboratory platform developers towards the most effective design of their platforms, The analysis of the results showed that educators would like the technical content of the laboratory to cover basic communication techniques, microwave circuits and devices, antennas and propagation, RF technology, and radio system design aspects of modern telecommunication systems. They would therefore like the laboratory instrumentation to be designed to that end. The educators also reported the need for advanced experimental setups which require expensive RF measurement devices. The discrepancy between university and technical college views was also considered in this paper.Article Citation - WoS: 10Citation - Scopus: 15An Rfid Based Indoor Tracking Method for Navigating Visually Impaired People(Tubitak Scientific & Technological Research Council Turkey, 2010) Oktem, Rusen; Aydin, ElifThis paper tackles the RFID based tracking problem in an obscured indoor environment. The proposed solution is an integral part of a navigation aid for guiding visually impaired people in a store. It uses RF signal strengths and is based on the Bayes Decision Theory. An observation vector is formed by received radio signal strength indication values, transmitted from three transmitters at distinct frequencies in the UHF band. The indoor area is divided into square grids, where each grid is considered as a class. The problem of tracking is expressed as classifying the observed radio signal strengths to the most likely class. A classification rule is formulated by incorporating a priori assumptions appropriate for the studied model. The proposed approach is tested in a laboratory environment. The results prove that the proposed approach is promising in tracking especially when the tracked person is guided by a system.
