Researcher:
Ürey, Hakan

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Hakan

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Ürey

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Researcher Of Publications: search.filters.isAuthorOfPublication.99202acc-f1df-4e28-89ea-da7d4b8ebae3

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Now showing 1 - 10 of 197
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    Exploring projection based mixed reality with tangibles for nonsymbolic preschool math education
    (Assoc Computing Machinery, 2019) N/A; N/A; Department of Psychology; Department of Media and Visual Arts; Department of Electrical and Electronics Engineering; Salman, Elif; Beşevli, Ceylan; Göksun, Tilbe; Özcan, Oğuzhan; Ürey, Hakan; Master Student; Researcher; Faculty Member; Faculty Member; Faculty Member; Department of Psychology; Department of Media and Visual Arts; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Social Sciences and Humanities; College of Engineering; N/A; N/A; 47278; 12532; 8579
    A child's early math development can stem from interactions with the physical world. Accordingly, current tangible interaction studies focus on preschool children's formal (symbolic) mathematics, i.e. number knowledge. However, recent developmental studies stress the importance of nonsymbolic number representation in math learning, i.e. understanding quantity relations without counting(more/less). To our knowledge, there are no tangible systems based on this math concept. We developed an initial tangible based mixed-reality(MR) setup with a small tabletop projector and depth camera. Our goal was observing children's interaction with the setup to guide our further design process towards developing nonsymbolic math trainings. In this paper we present our observations from sessions with four 3-to-5 year old children and discuss their meaning for future work. Initial clues show that our MR setup leads to exploratory and mindful interactions, which might be generalizable to other tangible MR systems for child education and could inspire interaction design studies.
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    Light engine and optics for HELIUM3D auto-stereoscopic laser scanning display
    (IEEE, 2011) Willman, Eero; Baghsiahi, Hadi; Day, Sally E.; Selviah, David R.; Fernandez, F. Anibal; N/A; Department of Electrical and Electronics Engineering; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Akşit, Kaan; Ölçer, Selim; Erden, Erdem; Chellappan, Kishore Velichappattu; Ürey, Hakan; PhD Student; Other; Master Student; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; N/A; 8579
    This paper presents a laser-based auto-stereoscopic 3D display technique and a prototype utilizing a dual projector light engine. The solution described is able to form dynamic exit pupils under the control of a multi-user head-tracker. A prototype completed recently is able to provide a glasses-free solution for a single user at a fixed position. At the end of the prototyping phase it is expected to enable a multiple user interface with an integration of the pupil tracker and the spatial light modulator.
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    Head-worn mixed reality projection display application
    (Association for Computing Machinery, 2014) Kade, Daniel; N/A; Department of Media and Visual Arts; Department of Electrical and Electronics Engineering; Akşit, Kaan; Özcan, Oğuzhan; Ürey, Hakan; PhD Student; Faculty Member; Faculty Member; Department of Media and Visual Arts; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Social Sciences and Humanities; College of Engineering; N/A; 12532; 8579
    The main goal of this research is to develop a mixed reality (MR) application to support motion capture actors. This application allows seeing and exploring a digital environment without occluding the actor's visual field. A prototype is built by combining a retro-reflective screen covering surrounding walls and a headband consisting of a laser scanning projector with a smartphone. Built-in sensors of a smartphone provide navigation capabilities in the digital world. The integrated system has some unique advantages, which are collectively demonstrated for the first time: (i) providing fixed field-ofview (50o in diagonal), fixed retinal images at full-resolution, and distortion-free images that are independent of the screen distance and shape; (ii) presenting different perspectives to the users as they move around or tilt their heads, (iii) allowing a focus-free and calibration-free display even on non-flat surfaces using laser scanning technology, (iv) enabling multiple users to share the same screen without crosstalk due to the use of retro-reflectors, and (v) producing high brightness pictures with a projector of only 15 lm; due to a high-gain retro-reflective screen. We demonstrated a lightweight, comfortable to wear and low cost head-mounted projection display (HMPD) which acts as a stand-a-lone mobile system. Initial informal functionality tests have been successfully performed. The prototype can also be used as a 3D stereo system using the same hardware by additionally mounting polarized glasses and an active polarization rotator, while maintaining all of the advantages listed above.
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    High-resolution beam steering using microlens arrays
    (Optical Soc Amer, 2006) N/A; N/A; Department of Electrical and Electronics Engineering; Akatay, Ata; Ataman, Çağlar; Ürey, Hakan; Master Student; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 8579
    Imaging or beam-steering systems employing a periodic array of microlenses or micromirrors suffer from diffraction problems resulting from the destructive interference of the beam segments produced by the array. Simple formulas are derived for beam steering with segmented apertures that do not suffer from diffraction problems because of the introduction of a moving linear phase shifter such as a prescan lens before the periodic structure. The technique substantially increases the resolution of imaging systems that employ microlens arrays or micromirror arrays. Theoretical, numerical, and experimental results demonstrating the high-resolution imaging concept using microlens arrays are presented.
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    Modeling and characterization of comb-actuated resonant microscanners
    (Iop Publishing Ltd, 2006) N/A; Department of Electrical and Electronics Engineering; Ataman, Çağlar; Ürey, Hakan; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 8579
    The dynamics of the out-of-plane comb-drive actuator used in a torsional resonant mode microscanner is discussed. The microscanner is fabricated using the standard SOI technology by Fraunhofer, IPMS and utilized in various display, barcode scanning, spectroscopy and other imaging applications. The device is a parametrically excited system and exhibits hysteretic frequency response, nonlinear transient response, subharmonic oscillations, multiple parametric resonances, and alternating-oscillation-frequency behavior. Analytical and numerical models are developed to predict the parametric system dynamics. The analytical model is based on the solution of the linear Mathieu equation and valid for small angular displacements. The numerical model is valid for both small and large deflection angles. The analytical and numerical models are validated with the experimental results under various ambient pressures and excitation schemes and successfully predict the dynamics of the parametric nature of the microscanner. As many as four parametric resonances are observed at 30 mTorr. The models developed in this paper can be used to optimize the structure and the actuator.
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    Resonant PZT MEMS scanners with integrated angle sensors
    (IEEE Computer Society, 2014) Brown, Dean; Davis, Wyatt; N/A; Department of Electrical and Electronics Engineering; N/A; Department of Electrical and Electronics Engineering; Baran, Utku; Holmstrom, Sven; Çakmak, Onur; Ürey, Hakan; Master Student; Researcher; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 8579
    Several high performing PZT-actuated MEMS laser scanners utilizing mechanical coupling are designed, fabricated, and characterized. Optical angles up to 59.3 deg. and θoptD·fn-products up to 3052 deg.·mm·Hz are demonstrated. These are the highest performing MEMS scanners in the literature. An angle sensor is integrated into one scanner design without any additional processing. The sensor response shows a linear relationship with the mirror rotation. A closed-loop drive was demonstrated using the scanner output.
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    Comb-actuated resonant torsional microscanner with mechanical amplification
    (IEEE-Inst Electrical Electronics Engineers Inc, 2010) Brown, Dean; Davis, Wyatt O.; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; N/A; Department of Electrical and Electronics Engineering; Arslan, Aslıhan; Holmstrom, Sven; Gökçe, Sertan Kutal; Ürey, Hakan; Researcher; Researcher; Master Student; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 8579
    A comb-actuated torsional microscanner is developed for high-resolution laser-scanning display systems. Typical torsional comb-drive scanners have fingers placed around the perimeter of the scanning mirror. In contrast, the structure in this paper uses cascaded frames, where the comb fingers are placed on an outer drive frame, and the motion is transferred to the inner mirror frame with a mechanical gain. The structure works only in resonant mode without requiring any offset in the comb fingers, keeping the silicon-on-insulator-based process quite simple. The design intent is to improve actuator efficiency by removing the high-drag fingers from the high-velocity scanning mirror. Placing them on the lower velocity drive frame reduces their contribution to the damping torque. Furthermore, placement on the drive frame allows an increase of the number of fingers and their capacity to impart torque. The microscanner exhibits a parametric response, and as such, the maximum deflection is found when actuated at twice its natural frequency. Analytical formulas are given for the coupled-mode equations and frame deflections. A simple formula is derived for the mechanical-gain factor. For a 1-mm x 1.5-mm oblong scanning mirror, a 76. total optical scan angle is achieved at 21.8 kHz with 196-V peak-to-peak excitation voltages. [2009-0304]
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    16.4: the optics of an autostereoscopic multiview display
    (SID, 2010) Baghsiahi, Hadi; Selviah, David R.; Willman, Eero; Fernández, Anibal; Day, Sally E.; Surman, Phil A.; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Erden, Erdem; Chellappan, Kishore Velichappattu; Ürey, Hakan; Master Student; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; 8579
    An autostereoscopic head-tracked back projection display that uses an RGB laser illumination source and a fast light engine is described. Images are horizontally scanned columns controlled by a spatial light modulator that directs two or more images in the directions of the apposite viewers 'eyes.
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    Design and characterization of micromachined sensor array integrated with CMOS based optical readout
    (Elsevier Science Sa, 2014) Temiz, Yüksel; Leblebici, Yusuf; Torun, Hamdi; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Erarslan, Refik Burak; Adiyan, Ulaş; Lüleç, Sevil Zeynep; Ölçer, Selim; Ürey, Hakan; Other; PhD Student; Master Student; Other; Faculty Member; Department of Electrical and Electronics Engineering; N/A; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; N/A; 8579
    This paper reports a micro electro-mechanical system (MEMS) based sensor array integrated with CMOSbased optical readout. The integrated architecture has several unique features. MEMS devices are passive and there are no electrical connections to the MEMS sensor array. Thus, the architecture is scalable to large array formats for parallel measurement applications and can even be made as a disposable cartridge in the future using self-aligning features. A CMOS-based readout integrated circuit (ROIC) is integrated to the MEMS chip. Via holes are defined on ROIC by customized post-processing and MEMS chip is thinned down by a grinding process to enable integrated optical readout. A diffraction grating interferometerbased optical readout is realized by pixel-level illumination of the MEMS chip through the via holes and by capturing the reflected light using a photodetector array on the CMOS chip. A model for the optical readout principle has been developed using Fourier optics. (C) 2013 Elsevier B.V. All rights reserved.
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    Label-free and high-throughput detection of biomolecular interactions using a flatbed scanner biosensor
    (Amer Chemical Soc, 2017) Avci, Oguzhan; Seymour, Elif; Unlu, M. Selim; Ozkumur, Ayca Yalcin; N/A; Department of Electrical and Electronics Engineering; Aygün, Uğur; Ürey, Hakan; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Sciences and Engineering; College of Engineering; N/A; 8579
    Fluorescence based microarray detection systems provide sensitive measurements; however, variation of probe immobilization and poor repeatability negatively affect the final readout, and thus quantification capability of these systems. Here, we demonstrate a label-free and high-throughput optical biosensor that can be utilized for calibration of fluorescence microarrays. The sensor employs a commercial flatbed scanner, and we demonstrate transformation of this low cost (similar to 100 USD) system into an Interferometric Reflectance Imaging Sensor through hardware and software modifications. Using this sensor, we report detection of DNA hybridization and DNA directed antibody immobilization on label-free microarrays with a noise floor of similar to 30 pg/mm(2), and a scan speed of 5 s (50 s for 10 frames averaged) for a 2 mm X 2 mm area. This novel system may be used as a standalone label-free sensor especially in low-resource settings, as well as for quality control and calibration of microarrays in existing fluorescence-based DNA and protein detection platforms.