Seungbae Lee

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A technique in which a micromechanical resonator is operated at large amplitudes while in situ localized annealed to temperatures exceeding 880oC is shown to be an effective method for both removal of surface contaminants and for possible “redistribution” of the structural material towards substantially higher quality factor Q and greatly enhanced drift(More)
Clear differences in the phase noise performance of a 10 MHz MEMS-based micromechanical resonator oscillator have been measured using sustaining circuits with and without automatic-level control (ALC), and with differing mechanisms for ALC. In particular, low output power oscillators referenced to high-Q clamped-clamped beam μmechanical resonators exhibit(More)
The quartz crystal used in the reference oscillator in a wireless communication transceiver is among the most difficult to integrate on chip. On-chip devices capable of matching its Q (on the order of 10,000) and temperature stability (<35ppm over 0-70C) are generally unavailable. Recently, an on-chip vibrating clamped-clamped beam (CC-beam) micromechanical(More)
A hybrid two-dimensional position sensing system is designed for mouse applications. The system measures the acceleration of hand-movements which are converted into two-dimensional location coor-dinates. The system consists of four major components: 1) MEMS accelerometers, 2) CMOS analog read-out circuitry, 3) an accelera-tion magnitude extraction module,(More)
Sustained changes in network activity cause homeostatic synaptic plasticity in part by altering the postsynaptic accumulation of N-methyl-D-aspartate receptors (NMDAR) and α-amino-3-hydroxyle-5-methyl-4-isoxazolepropionic acid receptors (AMPAR), which are primary mediators of excitatory synaptic transmission. A key trafficking modulator of NMDAR and AMPAR(More)
To investigate the spatial and temporal frequency tunings for stereopsis, we measured the contrast sensitivity for depth discrimination with variable spatiotemporal frequencies and disparities using drifting sinusoidal gratings. The results showed that the contrast sensitivity changed with the stimulus disparity and the disparity tuning function varied with(More)
Significant innovations in mobile technologies are enabling mobile users to make real-time actionable decisions based on balancing opportunities and risks to take coordinated actions with other users in their workplace. This requires a new distributed analytic framework that collects relevant information from internal and external sources, performs(More)