Jeongil Choi

This paper discusses the design of a single channel full-duplex wireless transceiver. The design uses a combination of RF and baseband techniques to achieve full-duplexing with minimal effect on link reliability. Experiments on real nodes show the full-duplex prototype achieves median performance that is within 8% of an ideal full-duplexing system.

Drag reduction in turbulent channel and pipe e ows by spanwise (circumferential) wall oscillations is studied numerically. The ine uence of the wall oscillation on near-wall streamwise vortices is examined. By the use of the Stokes second problem, a wall-normal distanceparameter and an acceleration parameterare obtained toestimate the drag reduction rate. A simple equation is derived for expressing the drag reduction rate by spanwise wall oscillations. The relation between near-wall streamwise v

The effect of human activity on contaminant transport may be important in design and operation of clean or isolation rooms in chemical or pharmaceutical industries and intensive care units for airborne infectious disease control in a hospital. The present simulations demonstrate details of contaminant transport in such indoor environments during human motion events and show that simulation-based sensitivity analysis can be utilized for the diagnosis of contaminant infiltration and for better env

A dynamic single-path mathematical model was developed that is capable of analyzing detailed deposition patterns of inhaled particles in human lungs. Weibel's symmetric lung morphology was adopted as the basic lung structure, and detailed transport processes were evaluated numerically using the fully implicit procedure. Deposition efficiencies by specific mechanisms were individually examined for accuracy and new empirical formulas were incorporated whenever appropriate. Deposition in the alveol

The Lagrangian dispersion of fluid particles in inhomogeneous turbulence is investigated by a direct numerical simulation of turbulent channel flow. Lagrangian velocity and acceleration along a particle trajectory are computed by employing several interpolation schemes. Among the schemes tested, the four-point Hermite interpolation in the homogeneous directions combined with Chebyshev polynomials in the wall-normal direction seems to produce most reliable Lagrangian statistics. Inhomogeneity of

UNLABELLED: An immersed boundary method for particulate flow in an Eulerian framework is utilized to examine the effects of complex human motion on the transport of trace contaminants. The moving human object is rendered as a level set in the computational domain, and realistic human walking motion is implemented using a human kinematics model. A large eddy simulation (LES) technique is used to simulate the fluid and particle dynamics induced by human activity. Parametric studies are conducted w

Simulations of compressible boundary-layer flow at three different Reynolds numbers (Re δ = 5.59 × 10 4 , 1.78 × 10 5 , and 1.58 x 10 6 ) are performed using a hybrid large-eddy simulation/Reynolds-averaged Navier-Stokes method. Variations in the recycling/rescaling method, the higher order extension, the choice of primitive variables, the Reynolds-averaged Navier-Stokes to large eddy simulation transition parameters, and the mesh resolution are considered in order to assess the model. The resul

Recent work has shown the possibility of implementing full-duplex wireless radios using commodity hardware. We discuss the possibility of extending full-duplex designs to support multiple input, multiple output (MIMO) systems. We explore how such a design could lead to a rethinking of wireless networks. We discuss various applications of full-duplex radios and the gains possible with those applications. We also discuss some of the challenges present in getting such radios and their applications