Researcher:
Ergen, Onur

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Onur

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Ergen

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Ergen, Onur

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2019 - 20206

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    Real time chemical and mechanical human motion monitoring with aerogel-based wearable sensors
    (Royal Soc Chemistry, 2020) Saraç, Feriha Eylem; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; N/A; Department of Physics; Department of Chemistry; Ergen, Onur; Çelik, Ecem; Ünal, Ahmet Hamdi; Erdolu, Mert Yusuf; Ünal, Uğur; Researcher; Faculty Member; PhD Student; Undergraduate Student; Undergraduate Student; Faculty Member; Department of Electrical and Electronics Engineering; Department of Physics; Department of Chemistry; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; 272106; N/A; N/A; 42079
    Wearable bioelectronic systems are one of the most important tools for human health and motion monitoring. However, there is still a great challenge to fabricate high-performance flexible devices with a conformal integration of the human body and there is no single device that can collect and correlate data simultaneously from chemical and mechanical signals of the human body. We recently developed a new method to build aerogel-based strain and sweat sensors (aB-SSS) that can effectively extract real-time information by combining involuntary human motion and chemical signals due to their gradient functionalities. these sensors provide good mechanical integrity and allow high-density power generation during subtle human motion, Allowing sweat monitoring by measuring pH, ion concentration, perspiration rate,etc.
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    Effective capacity and outage probability assessment of multiple-relay cognitive communication systems in Nakagami-m and Rayleigh fading channel
    (Wiley, 2020) Zahedi, Abdulhamid; Shayea, Ibraheem; El-Saleh, Ayman A.; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Ergen, Onur; Ergen, Mustafa; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; College of Engineering; N/A; N/A
    The radio spectrum of communication systems is largely occupied by wideband technologies, and thus, efficient usage of spectrum is a crucial requirement from regulators' and service providers' perspectives. Cognitive communication has been proposed as a potential solution to resolve the spectrum scarcity problem. Cognitive radio schemes can be jointly applied with cooperative communications to improve the performance under both overlay and underlay strategies as the two main cognitive strategies supported by multiple relays. This combination significantly improves the reliability and capacity of data communication. In this paper, two QoS parameters, namely, the effective capacity and outage probability, have been thoroughly analyzed in a Nakagami-m fading channel that is the typical channel condition often considered in the transmission of communication systems. Closed-form expressions are obtained for effective capacity and outage probability in both underlay and overlay strategies. Simulation results verify the effectiveness of the mathematical modelling of the proposed QoS parameters.
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    PublicationOpen Access
    Hexagonal boron nitride incorporation to achieve high performance Li4Ti5O12 electrodes
    (American Institute of Physics (AIP) Publishing, 2020) Department of Electrical and Electronics Engineering; Ergen, Onur; Department of Electrical and Electronics Engineering; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Engineering; Graduate School of Sciences and Engineering; 272106
    There is an increasing demand for fast charging and high capacity lithium ion batteries. However, conventional Li-ion battery chemistries cannot meet the stringent requirements of these demands due to the poor performance of graphite anodes, especially on safety during fast charging. Finding the right anode material that can replace conventional graphite while providing high capacity is very challenging. Today, lithium titanium oxide (LTO) is considered one of the most attractive anode materials that can provide the desired ultra-fast charging ability (>10C) with high safety. However, it has many serious drawbacks when compared to the existing graphite anodes, including poor intrinsic conductivity, narrow electrochemical window, etc. Extensive research has been done to overcome these problems, especially in developing new LTO composite materials with reduced graphene oxide. However, even these methods have rapid capacity fading at high current densities, >5C, due to increased internal resistance and polarization losses. Here, we demonstrate an effective way to improve LTO composite materials by developing unique nanoengineered three-dimensional frameworks with hexagonal boron nitride (h-BN) addition. Li-ion cells with h-BN incorporation exhibit excellent performance and operational stability, especially at fast and ultra-fast charging rates, >10C.
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    PublicationOpen Access
    Edge on wheels with OMNIBUS networking for 6G technology
    (Institute of Electrical and Electronics Engineers (IEEE), 2020) Ergen, Mustafa; İnan, Feride; Shayea, Ibraheem; Tüysüz, Mehmet Fatih; Azizan, Azizul; Üre, Nazim Kemal; Nekovee, Maziar; Department of Electrical and Electronics Engineering; Ergen, Onur; Department of Electrical and Electronics Engineering; College of Engineering
    In recent years, both the scientific community and the industry have focused on moving computational resources with remote data centres from the centralized cloud to decentralised computing, making them closer to the source or the so called "edge" of the network. This is due to the fact that the cloud system alone cannot sufficiently support the huge demands of future networks with the massive growth of new, time-critical applications such as self-driving vehicles, Augmented Reality/Virtual Reality techniques, advanced robotics and critical remote control of smart Internet-of-Things applications. While decentralised edge computing will form the backbone of future heterogeneous networks, it still remains at its infancy stage. Currently, there is no comprehensive platform. In this article, we propose a novel decentralised edge architecture, a solution called OMNIBUS, which enables a continuous distribution of computational capacity for end-devices in different localities by exploiting moving vehicles as storage and computation resources. Scalability and adaptability are the main features that differentiate the proposed solution from existing edge computing models. The proposed solution has the potential to scale infinitely, which will lead to a significant increase in network speed. The OMNIBUS solution rests on developing two predictive models: (i) to learn timing and direction of vehicular movements to ascertain computational capacity for a given locale, and (ii) to introduce a theoretical framework for sequential to parallel conversion in learning, optimisation and caching under contingent circumstances due to vehicles in motion.
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    PublicationOpen Access
    Screen engineered field effect Cu2O based solar cells
    (Institute of Electrical and Electronics Engineers (IEEE), 2020) Department of Electrical and Electronics Engineering; Ergen, Onur; Çelik, Ecem; Ünal, Ahmet Hamdi; Erdolu, Mert Yusuf; Faculty Member; PhD Student; Undergraduate Student; Department of Electrical and Electronics Engineering; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Engineering; 272106; N/A; N/A; N/A
    We demonstrate cuprous oxide (Cu2O) based screen engineered field effect solar cells with a record breaking efficiency, exceeding 3.486%, for Cu2O based p-n homojunction. In this architecture, CuO nanowire interphase is successfully employed in the Cu2O fabrication by effectively serving as a simultaneous ohmic current collector. These screen engineered field effect photovoltaic principles are essential in developing promising photovoltaics architectures for hard-to-dope materials that, in principle, enable extremely low-cost, high efficiency solar cells.
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    PublicationOpen Access
    Ai driven advanced internet of things (Iotx(2)): the future seems irreversibly connected in medicine
    (Turkish Society of Cardiology, 2019) Belcastro, Kristen D.; Department of Electrical and Electronics Engineering; Ergen, Onur; Department of Electrical and Electronics Engineering; College of Engineering; 272106