도형록 교수

A Gaussian multiple-input multiple-output broadcast channel (MIMO GBC) is considered. Throughout the paper it is assumed that 1) input signals are Gaussian and 2) perfect channel state information is available at the transmitter and at the receivers. By considering each data stream as a single user, the uplink-downlink signal-to-interference-plus-noise (SINR) duality is generalized to the MIMO case with general cross-talk matrix. The duality is subsequently applied to finding the solution for th

Inlet unstart mechanism in an ethylene-fueled model scramjet is investigated using a pulsed arc-heated hypersonic wind tunnel simulating supersonic/hypersonic flight conditions (Mach 4.5, 6, and 9 flows). The inlet unstart is ca used by excessive heat release from ethylene combustion reactions with Mach 4.5 freestream flows of 500 K static temperature and 2,500 K stagnation temperature. Flame evolution during a test time of approximately 150 milliseconds is optically resolved by a fast framin g

The data-rate requirement for a data center interconnect is being switched to 400 Gb/s. For the optical interface, the electro-optical transmitter chip designed in the CMOS process has been proposed rather than the BiCMOS process as technology advances. On the other hand, vertical-cavity surface-emitting laser (VCSEL) has been a popular candidate for the optical modulation device of the 400 GbE interconnect because of its cost and packaging efficiency [1] –[7]. However, the high operating voltag

Potential determinants of the laser-induced breakdown spectra in N 2 –O 2 mixtures are investigated with varying species concentration, laser energy, and exposure time (equal to the detector’s intensifier gate time). A focused laser beam with pulse energy 29 mJ, 38 mJ, or 46 mJ generates the breakdown plasma in a N 2 mixture containing O 2 from 0% to 21% in mole fraction. Time-resolved measurements of the breakdown emission spectra with 2 or 10 ns exposure are carried out beginning from the arri

Ethylene flame dynamics in a model scramjet is investigated using a pulsed-arc-heated hypersonic wind tunnel simulating supersonic/hypersonic flight conditions (Mach 4.5, 6 and 9 flows of up to 3,500K stagnation temperature). A partially-premixed ethylene flame is auto-ignited with Mach 4.5, 6 and 9 freestream flows in a region downstream of a fuel jet where the high enthalpy flow is compressed and decelerated by incident/reflected shockwaves and development of boundary layers. This flame propag