Yazar "Hah, Dooyoung" için listeleme
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Absorption enhancement by semi-cylindrical-shell-shaped structures for an organic solar cell application
Hah, Dooyoung (OPTICAL SOC AMER, 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA, 2020)Organic solar cells are attractive for various applications with their flexibility and low-cost manufacturability. In order to increase their attractiveness in practice, it is essential to improve their energy conversion ... -
All-polymer ultrasonic transducer design for an intravascular ultrasonography application
Hah, Dooyoung (TUBITAK SCIENTIFIC & TECHNICAL RESEARCH COUNCIL TURKEY, ATATURK BULVARI NO 221, KAVAKLIDERE, ANKARA, 00000, TURKEY, 2019)Intravascular ultrasonography (IVUS), a medical imaging modality, is used to obtain cross-sectional views of blood vessels from inside. In IVUS, transducers are brought to the proximity of the imaging targets so that ... -
AlN Piezoelectric Quad-Actuators for 2D Optical Micro Scanning
Hah, Dooyoung (TAYLOR & FRANCIS LTD, 2022)Piezoelectric actuation has been one of the frequent choices for optical micro scanning. In most of the cases, lead zirconate titanate (PZT) has been used as the piezoelectric material. However, PZT has a potential issue ... -
Analysis of electret-based vibration energy harvesting devices with curved-beam hinges
Hah, Dooyoung (SAGE Publications Ltd, 2023)Recently, vibration energy harvesting devices have gained growing interests. One of the main requirements for them is a broad bandwidth owing to stochastic spectral characteristics of the general vibration sources. Among ... -
Analysis of optical gyroscopes with vertically stacked ring resonators
Hah, Dooyoung (TUBITAK SCIENTIFIC & TECHNICAL RESEARCH COUNCIL TURKEYATATURK BULVARI NO 221, KAVAKLIDERE, ANKARA 00000, TURKEY, 2021)Without any moving part, optical gyroscopes exhibit superior reliability and accuracy in comparison to mechanical sensors. Microring-resonator-based optical gyroscopes emerged as alternatives for bulky conventional Sagnac ... -
Analytical design of MEMS variable capacitors based on shaped-finger comb-drives
Hah, Dooyoung (SPRINGER HEIDELBERG, 2022)A variable capacitor is one of the widely used components in radio frequency (RF) circuits. Variable capacitors can benefit from the microelectromechanical systems (MEMS) technology, to be equipped with attractive ... -
C-band optical filters with micromechanical tuning
Hah, Dooyoung (SPRINGER HEIDELBERGTIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANY, 2018)Tunable optical filters that cover the entire range of the C-band (1530-565 nm) are designed by utilizing the Vernier effect, i.e. series coupling of microring resonators of different sizes, and the micromechanical tuning ... -
Clinical probe utilizing surface enhanced Raman scattering
Kim, Jeonghwan; Hah, Dooyoung; Daniels-Race, Theda; Feldman, Martin (A V S AMER INST PHYSICS, STE 1 NO 1, 2 HUNTINGTON QUADRANGLE, MELVILLE, NY 11747-4502 USA, 2014)Conventional Raman scattering is a well-known technique for detecting and identifying complex molecular samples. In surface enhanced Raman scattering, a nanorough metallic surface close to the sample enormously enhances ... -
A design method of comb-drive actuators for linear tuning characteristics in mechanically tunable optical filters
Hah, Dooyoung (SPRINGER HEIDELBERGTIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANY, 2017)A new method is proposed in design of comb-drive actuators for specific voltage-displacement characteristics with finger gaps as the design parameters. The design method proposed by the author previously is further refined ... -
Design of capacitive micromachined ultrasonic transducers (CMUTs) on a flexible substrate for intravascular ultrasonography (IVUS) applications
Hah, Dooyoung; Je, Chang Han; Lee, Sung-Q (IEEE345 E 47TH ST, NEW YORK, NY 10017 USA, 2017)Effects of substrate bending to the characteristics of capacitive miniaturized ultrasonic transducers (CMUTs) on a flexible substrate are studied through finite element analysis (FEA) for the design purpose. The target ... -
Design of Mechanically Tunable Optical Filters with Microring Resonators
Hah, Dooyoung; Bordelon, John (IEEE, 2015)Design strategies for the mechanically tunable optical filters with microring resonators and comb-drive actuators are discussed. Electromechanical simulation results are combined with the electromagnetic analysis of the ... -
Design of Wide-Band Tunable Optical Filters with Cascaded Microring Resonators and Shaped-Finger Comb-Drive Actuators
Hah, Dooyoung (IEEE345 E 47TH ST, NEW YORK, NY 10017 USA, 2016)Utilizing the Vernier effect, series coupling of multiple microring resonators with different sizes is used to design a wide-band (free spectral range: 36 nm) tunable filter. For index modulators that shift the filter ... -
Electret vibration energy harvesters with symmetrically configured curved-beam hinges
Hah, Dooyoung (SPRINGER, 2024)For vibration energy harvesters, broadband power spectral characteristics are often desirable. One way of achieving broadband spectrum is to employ curved-beam hinges, utilizing their nonlinear spring characteristics. In ... -
An FEM Study of Die Attach Packaging Effect on Nanomechanical Si Optical Filters
Seok, Seonho; Hah, Dooyoung (IEEE345 E 47TH ST, NEW YORK, NY 10017 USA, 2017)This paper presents a finite element analysis of die attach packaging stress effect on emerging nanomechanical silicon optical filters. The proposed silicon optical filter is composed of Si waveguides and a microring ... -
Flexible and Ecofriendly Keypad Based on Paper and Pencil
Er, Şahane Firdevs; Kalabey, Nurefşan; Hah, Dooyoung (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2023)Pencil-on-paper electronics has gained growing interests as cost-effective, ecofriendly, flexible, and light-weight devices for various applications. In this letter, a flexible keypad employing pencil-on-paper capacitive ... -
Linear variable optical attenuators with shaped-finger comb-drive actuators
Hah, Dooyoung (OPTICAL SOC AMER, 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA, 2020)A design method is proposed for variable optical attenuators (VOAs), aiming at linear attenuation-voltage characteristics, and verified by finite element analysis. Devices of interest are planar VOAs based on microelectr ... -
Planar MEMS Variable Optical Attenuators (VOAs) with Linear Attenuation-Voltage Characteristics
Hah, Dooyoung (IEEE, 345 E 47TH ST, NEW YORK, NY 10017 USA, 01.01.2019)Variable optical attenuators (VOAs) are essential components in wavelength division multiplexing (WDM) networks, light waveform generators, and optical fiber test equipment. Among various types of planar MEMS VOAs, a shutter ... -
Quasi-Static Operation of 2-Axis-Tilt Microscanners with AlN Piezoelectric Quad-Actuators
Hah, Dooyoung (IEEE, 2021)Aluminum nitride (AlN) started to draw attentions as a material for piezoelectric actuation owing to its CMOS process compatibility and safeness for biomedical applications. Due to its relatively low piezoelectric ... -
Respiration monitoring using a paper-based wearable humidity sensor, a step forward to clinical tests
Solak, İrfan; Gençer, Serife; Yıldırım, Beyza; Öznur, Emine; Hah, Dooyoung; Icoz, Kutay (ELSEVIER, 2023)Monitoring respiratory variables can provide valuable information for clinical applications and sport activities. Paper-based wearable respiration monitoring systems have great advantages and potential, they are ... -
RF MEMS variable attenuators with improved dB-linearity
Hah, Dooyoung (SPRINGER HEIDELBERG, 2023)A variable attenuator is one of the essential components in radio frequency (RF) systems, such as automatic gain control amplifiers and full-duplex systems. Variable attenuators based on microelectromechanical systems ...
