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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Item Metadata only A biofeedback based virtual reality game for pediatric population (BioVirtualPed): a feasibility trial(Elsevier Inc., 2024) 0000-0002-2031-7967; 0000-0003-1999-9179; 0000-0002-0083-7754; 0000-0002-7544-5974; N/A; N/A; Department of Electrical and Electronics Engineering; N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Ürey, Hakan; Semerci, Remziye; Umaç, Eyşan Hanzade; Gürsoy, Beren Semiz; Dinçer, Betül; Sayın, Ata; Faculty Member; Faculty Member; PhD Student; Faculty Member; Undergraduate Student; Undergraduate Student; College of Engineering; School of Nursing; Graduate School of Health Sciences; College of Engineering; College of Engineering; College of Engineering; 8579; 216754; N/A; 332403; N/A; N/AObjective: This trial aims to assess the acceptability, feasibility, and safety of BioVirtualPed, a biofeedback-based virtual reality (VR) game designed to reduce pain, anxiety, and fear in children undergoing medical procedures. Methods: An Oculus Quest 2 headset was used in the VR experience, respiratory data was captured using an ADXL354 accelerometer, and these data were integrated into the game with ArdunioUno software. The sample of this study consisted of 15 pediatric oncology patients aged 6 to 12 years between July and August 2023. BioVirtualPed's acceptability, feasibility, and safety were evaluated through child and expert feedback, alongside metrics including the System Usability Scale, Wong-Baker Pain Rating Scale, Child Fear Scale, Child Anxiety Scale-Status, Satisfaction Scoring, and various feasibility and safety parameters. Results: Regarding the acceptability, the expert evaluation showed a mean score of 122.5 ± 3.53, indicating high usability for the system. All children provided positive feedback, and both children and their mothers reported high satisfaction with using BioVirtualPed. The BioVirtualPed was feasible for reducing children's pain, fear, and anxiety levels. All the children complied with the game, and no one withdrew from the trial. BioVirtualPed did not cause symptoms of dizziness, vomiting, or nausea in children and was found to be safe for children. Conclusion: The findings showed that BioVirtualPed meets the following criteria: feasibility, user satisfaction, acceptability, and safety. It is a valuable tool to improve children's experience undergoing port catheter needle insertion procedures. Implication for Nursing Practice: Integration of VR interventions with BioVirtualPed into routine nursing care practices has the potential to effectively manage the pain, anxiety, and fear experienced by children undergoing medical procedures. The safety, feasibility, and acceptability results are promising for further research and integration into pediatric healthcare practice. © 2024 Elsevier Inc.Item Metadata only On the reliability analysis of C-V2X mode 4 for next generation connected vehicle applications(IEEE, 2022) 0000-0002-7502-3122; 0000-0001-9438-5113; N/A; N/A; N/A; N/A; Karaagac, Sercan; Department of Electrical and Electronics Engineering; N/A; N/A; N/A; N/A; N/A; Ergen, Sinem Çöleri; Turan, Buğra; Kara, Yahya Şükür Can; Kümeç, Feyzi Ege; Kar, Emrah; Reyhanoğlu, Aslıhan; Faculty Member; PhD Student; Researcher; Researcher; Researcher; Researcher; Koc University – Ford Otosan Automotive Technologies Laboratory (KUFOTAL); College of Engineering; Graduate School of Sciences and Engineering; N/A; N/A; N/A; N/A; 7211; N/A; N/A; N/A; N/A; N/AVehicle-to-Everything Communication (V2X) technologies are provisioned to play an important role in increasing road safety by enabling advanced connected vehicle applications such as cooperative perception, cooperative driving, and remote driving. However, the reliability of the technology is limited mainly due to wireless communication channel characteristics. Therefore, investigation of V2X reliability aspects is crucial to utilize the technology efficiently. In this paper, we provide simulation and measurement-based reliability analysis of Cellular Vehicle-to-Everything (C-V2X) Mode 4 technology for various message sizes and Modulation and Coding Schemes (MCS) selections. We demonstrate that the Packet Delivery Ratio (PDR), a key communication performance metric, heavily depends on message size and selected MCS.Item Metadata only Spatio-temporal perception-distortion trade-off in learned video SR(IEEE Computer Society, 2023) 0000-0003-1465-8121; N/A; Department of Electrical and Electronics Engineering; N/A; Tekalp, Ahmet Murat; Rahimi, Nasrin; Faculty Member; PhD Student; Koç Üniversitesi İş Bankası Yapay Zeka Uygulama ve Araştırma Merkezi (KUIS AI)/ Koç University İş Bank Artificial Intelligence Center (KUIS AI); College of Engineering; Graduate School of Sciences and Engineering; 26207; N/APerception-distortion trade-off is well-understood for single-image super-resolution. However, its extension to video super-resolution (VSR) is not straightforward, since popular perceptual measures only evaluate naturalness of spatial textures and do not take naturalness of flow (temporal coherence) into account. To this effect, we propose a new measure of spatio-temporal perceptual video quality emphasizing naturalness of optical flow via the perceptual straightness hypothesis (PSH) for meaningful spatio-temporal perception-distortion trade-off. We also propose a new architecture for perceptual VSR (PSVR) to explicitly enforce naturalness of flow to achieve realistic spatio-temporal perception-distortion trade-off according to the proposed measures. Experimental results with PVSR support the hypothesis that a meaningful perception-distortion tradeoff for video should account for the naturalness of motion in addition to naturalness of texture. © 2023 IEEE.Item Metadata only 3D bioprinted organ-on-chips(John Wiley and Sons Inc, 2023) 0000-0003-4604-217X; 0009-0004-1518-6706; 0000-0002-5295-5701; 0000-0001-8888-6106; Mustafaoglu, Nur; Zhang, Yu Shrike; Department of Electrical and Electronics Engineering; N/A; N/A; N/A; Taşoğlu, Savaş; Birtek, Mehmet Tuğrul; Sarabi, Misagh Rezapour; Dabbagh, Sajjad Rahmani; Faculty Member; PhD Student; PhD Student; PhD Student; Koç Üniversitesi İş Bankası Yapay Zeka Uygulama ve Araştırma Merkezi (KUIS AI)/ Koç University İş Bank Artificial Intelligence Center (KUIS AI); KU Arçelik Research Center for Creative Industries (KUAR) / KU Arçelik Yaratıcı Endüstriler Uygulama ve Araştırma Merkezi (KUAR); College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 291971; N/A; N/A; N/AOrgan-on-a-chip (OOC) platforms recapitulate human in vivo-like conditions more realistically compared to many animal models and conventional two-dimensional cell cultures. OOC setups benefit from continuous perfusion of cell cultures through microfluidic channels, which promotes cell viability and activities. Moreover, microfluidic chips allow the integration of biosensors for real-time monitoring and analysis of cell interactions and responses to administered drugs. Three-dimensional (3D) bioprinting enables the fabrication of multicell OOC platforms with sophisticated 3D structures that more closely mimic human tissues. 3D-bioprinted OOC platforms are promising tools for understanding the functions of organs, disruptive influences of diseases on organ functionality, and screening the efficacy as well as toxicity of drugs on organs. Here, common 3D bioprinting techniques, advantages, and limitations of each method are reviewed. Additionally, recent advances, applications, and potentials of 3D-bioprinted OOC platforms for emulating various human organs are presented. Last, current challenges and future perspectives of OOC platforms are discussed. © 2022 The Authors. Aggregate published by SCUT, AIEI, and John Wiley & Sons Australia, Ltd.Item Metadata only Dynamic accommodation measurement using Purkinje reflections and machine learning(Nature Research, 2023) 0000-0002-2031-7967; 0000-0002-5083-5618; N/A; 0000-0002-3424-4981; Department of Electrical and Electronics Engineering; N/A; N/A; N/A; Ürey, Hakan; Şahin, Afsun; Aygün, Uğur; Özhan, Faik Ozan; Faculty Member; Faculty Member; PhD Student; Master Student; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); College of Engineering; School of Medicine; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 8579; 171267; N/A; N/AQuantifying eye movement is important for diagnosing various neurological and ocular diseases as well as AR/VR displays. We developed a simple setup for real-time dynamic gaze tracking and accommodation measurements based on Purkinje reflections, which are the reflections from front and back surfaces of the cornea and the eye lens. We used an accurate eye model in ZEMAX to simulate the Purkinje reflection positions at different focus distances of the eye, which matched the experimental data. A neural network was trained to simultaneously predict vergence and accommodation using data collected from 9 subjects. We demonstrated that the use of Purkinje reflection coordinates in machine learning resulted in precise estimation. The proposed system accurately predicted the accommodation with an accuracy better than 0.22 D using subject’s own data and 0.40 D using other subjects’ data with two-point calibration in tests performed with 9 subjects in our setup. © 2023, The Author(s).Item Metadata only Optimization theory and deep learning based resource allocation in net-zero-energy networks with short packets(IEEE-Inst Electrical Electronics Engineers Inc, 2023) 0000-0002-7502-3122; 0000-0002-1581-8206; Department of Electrical and Electronics Engineering; N/A; Ergen, Sinem Çöleri; Önalan, Aysun Gurur; Faculty Member; PhD Student; College of Engineering; Graduate School of Sciences and Engineering; 7211; N/ANet-zero-energy networks enable IoT applications by balancing harvested and consumed energy when the connection to the electric grid or changing batteries is not feasible for the information sources. This letter studies the optimization problem for minimizing the schedule length for net-zero-energy networks with short packets where the schedule length is defined as the total time duration required for the RF energy harvesting (EH) in the downlink and information transmission by exhausting the harvested energy in the uplink. The problem is nonlinear and non-convex, so hard to solve. To obtain a near-optimal solution, a bi-level optimization-based framework is proposed with the master problem searching for optimal EH duration iteratively and subproblems of calculating the schedule length for a given EH time in each iteration. Then, we propose a low complexity optimization theory based deep learning framework based on the simplification of the deep learning architecture by using optimality conditions. The proposed approaches outperform state-of-art algorithms in terms of schedule length. The optimization theory based deep learning approach further decreases the complexity.Item Metadata only A novel approach to quantify microsleep in drivers with obstructive sleep apnea by concurrent analysis of EEG patterns and driving attributes(IEEE-Inst Electrical Electronics Engineers Inc, 2024) 0000-0001-9067-6538; 0000-0002-7544-5974; 0000-0002-4041-4529; 0000-0001-5575-2195; 0000-0002-8286-7956; N/A; Department of Electrical and Electronics Engineering; N/A; N/A; N/A; Peker, Yüksel; Gürsoy, Beren Semiz; Çelik, Yeliz; Arbatlı, Semih; Minhas, Riaz; Faculty Member; Faculty Member; Researcher; PhD Student; Master Student; School of Medicine; College of Engineering; N/A; Graduate School of Health Sciences; Graduate School of Sciences and Engineering; 234103; 332403; N/A; N/A; N/AAccurate quantification of microsleep (MS) in drivers is crucial for preventing real-time accidents. We propose one-to-one correlation between events of high-fidelity driving simulator (DS) and corresponding brain patterns, unlike previous studies focusing general impact of MS on driving performance. Fifty professional drivers with obstructive sleep apnea (OSA) participated in a 50-minute driving simulation, wearing six-channel Electroencephalography (EEG) electrodes. 970 out-of-road OOR (microsleep) events (wheel and boundary contact >= 1 s), and 1020 on-road OR (wakefulness) events (wheel and boundary disconnection >= 1 s), were recorded. Power spectrum density, computed using discrete wavelet transform, analyzed power in different frequency bands and theta/alpha ratios were calculated for each event. We classified OOR (microsleep) events with higher theta/alpha ratio compared to neighboring OR (wakefulness) episodes as true MS and those with lower ratio as false MS. Comparative analysis, focusing on frontal brain, matched 791 of 970 OOR (microsleep) events with true MS episodes, outperforming other brain regions, and suggested that some unmatched instances were due to driving performance, not sleepiness. Combining frontal channels F3 and F4 yielded increased sensitivity in detecting MS, achieving 83.7% combined mean identification rate (CMIR), surpassing individual channel's MIR, highlighting potential for further improvement with additional frontal channels. We quantified MS duration, with 95% of total episodes lasting between 1 to 15 seconds, and pioneered a robust correlation (r = 0.8913, p<0.001) between maximum drowsiness level and MS density. Validating simulator's signals with EEG patterns by establishing a direct correlation improves reliability of MS identification for assessing fitness-to-drive of OSA-afflicted adults.Item Metadata only Multivariate extreme value theory based channel modeling for ultra-reliable communications(Institute of Electrical and Electronics Engineers Inc., 2023) 0000-0002-7502-3122; 0000-0002-5475-2238; Department of Electrical and Electronics Engineering; N/A; Ergen, Sinem Çöleri; Mehrnia, Niloofar; Faculty Member; PhD Student; College of Engineering; Graduate School of Sciences and Engineering; 7211; N/AAttaining ultra-reliable communication (URC) in fifth-generation (5G) and beyond networks requires deriving statistics of channel in ultra-reliable region by modeling the extreme events. Extreme value theory (EVT) has been previously adopted in channel modeling to characterize the lower tail of received powers in URC systems. In this paper, we propose a multivariate EVT (MEVT)-based channel modeling methodology for tail of the joint distribution of multi-channel by characterizing the multivariate extremes of multiple-input multiple-output (MIMO) system. The proposed approach derives lower tail statistics of received power of each channel by using the generalized Pareto distribution (GPD). Then, tail of the joint distribution is modeled as a function of estimated GPD parameters based on two approaches: logistic distribution, which utilizes logistic distribution to determine dependency factors among the Fréchet transformed tail sequence and obtain a bi-variate extreme value model, and Poisson point process, which estimates probability measure function of the Pickands angular component to model bi-variate extreme values. Finally, validity of the proposed models is assessed by incorporating the mean constraint on probability measure function of Pichanks coordinates. Based on the data collected within the engine compartment of Fiat Linea, we demonstrate the superiority of proposed methodology compared to the conventional extrapolation-based methods in providing the best fit to the multivariate extremes. AuthorItem Metadata only Ultra-broadband integrated optical filters based on adiabatic optimization of coupled waveguides(IEEE-Inst Electrical Electronics Engineers Inc, 2023) 0000-0001-7680-6818; N/A; Department of Electrical and Electronics Engineering; N/A; Mağden, Emir Salih; Görgülü, Kazım; Faculty Member; PhD Student; College of Engineering; Graduate School of Sciences and Engineering; 276368; N/ABroadband spectral filters are highly sought-after in many integrated photonics applications such as ultra-broadband wavelength division multiplexing, multi-band spectroscopy, and broadband sensing. In this study, we present the design, simulation, and experimental demonstration of compact and ultra-broadband silicon photonic filters with adiabatic waveguides. We first develop an optimization algorithm for coupled adiabatic waveguide structures, and use it to design individual, single-cutoff spectral filters. These single-cutoff filters are 1 x 2 port devices that optimally separate a broadband signal into short-pass and long-pass outputs, within a specified device length. We control the power roll-off and extinction ratio in these filters using the adiabaticity parameter. Both outputs of the filters operate in transmission, making it possible to cascade multiple filters in different configurations. Taking advantage of this flexibility, we cascade two filters with different cutoff wavelengths on-chip, and experimentally demonstrate band-pass operation. The independent and flexible design of these band edges enables filters with bandwidths well over 100 nm. Experimentally, we demonstrate band-pass filters with passbands ranging from 6.4 nm up to 96.6 nm. Our devices achieve flat-band transmission in all three of the short-pass, band-pass, and long-pass outputs with less than 1.5 dB insertion loss and extinction ratios of over 15 dB. These ultra-broadband filters can enable new capabilities for multi-band integrated photonics in communications, spectroscopy, and sensing applications.Item Metadata only Spatial modulation using signal space diversity(IEEE-Inst Electrical Electronics Engineers Inc, 2023) 0000-0001-5566-2392; N/A; 0000-0003-4778-8344; Department of Electrical and Electronics Engineering; N/A; N/A; Başar, Ertuğrul; Kurt, Mehmet Akif; Doğukan, Ali Tuğberk; Faculty Member; Master Student; PhD Student; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 149116; N/A; N/AIn this letter, a novel scheme, called spatial modulation (SM) using signal space diversity (SM-SSD), is proposed for future multiple-input multiple-output (MIMO) systems. In this scheme, consecutive time slots are modulated jointly, and the technique of signal and space diversity (SSD) is applied to spread the real and imaginary parts of data symbols over the time domain. In addition, novel active antenna activation pattern and time activation pattern selection algorithms are introduced. An upper bound expression for bit error rate (BER) is obtained and a diversity analysis is performed. Besides, a suboptimal solution for the optimization of rotation angles is put forward to maximize the minimum coding gain distance (MCGD). Monte Carlo simulations are performed to compare the BER performance of SM-SSD with the benchmark schemes, in the presence of both correlated and uncorrelated channels. Lastly, the change in the spectral efficiency is analyzed for different numbers of time slots and transmit antennas.