A surface-normal input/output volume holographic grating coupler (VHGC) operating at 1550nm wavelength region by using a 10μm-thick DuPont photopolymer film is designed and fabricated. The angular and wavelength responses of the input/output VHGC are investigated in order to validate applicability of this device in integrated optics and optical communications. The effect of incident-beam position on the output reflectance to determine optimum condition for input coupling is also presented. The fabricated input/output VHGC exhibited an angular selectivity of ~0.027°, a wavelength selectivity of ~0.8 nm, and an output peak reflectance of 34.13%.

JINPOONG, a walking robot using hydraulic pressure, requires a power source to operate the power pack. Therefore, power was supplied to JINPOONG by using an engine that has high power per unit engine weight.Hydraulic pump requires a constant rotating speed in order to supply stable hydraulic pressure because the pressure and flow rate changes according to rotating speed.This study proposes a way to maintain relatively stable rotating speed of engine with irregular and fluctuating load.

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