Jinsung Park

This paper presents the design and analysis of low flicker-noise RF mixers in a 0.18-mum CMOS process for C-band direct-conversion receivers. The low flicker-noise mixers are implemented by incorporating a double-balanced Gilbert-type configuration, the RF leakageless current bleeding technique, and the resonating technique for the tail capacitance. First, a double-balanced Gilbert-type mixer using the current bleeding technique has been fabricated and measured for lowering flicker corner freque

We report the scanning probe microscope (SPM)-based single-molecule recognition of biomolecular interactions between protein kinase and small ligands (i.e., ATP and Imatinib). In general, it is difficult to sense and detect the small ligands bound to protein kinase (at single-molecule resolution) using a conventional atomic force microscope (AFM) due to the limited resolution of conventional AFM for detecting the miniscule changes in molecular size driven by ligand binding. In this study, we hav

PFOA is a representative perfluorinated compound that is used as a surfactant in various industrial fields. However, because PFOA has severe side effects due to its strong toxicity, such as carcinogenesis, liver damage, and immune system damage, it is crucial to enable PFOA detection with high sensitivity. Herein, we developed a perfluorooctanoic acid (PFOA) surface-enhanced Raman scattering (SERS) sensor using self-assembled p-phenylenediamine (SAp-PD) nanoparticles and an Ag SERS substrate. Fo

Recent numerical simulations on two-dimensional model reaction-diffusion systems have revealed unusual spiral waves with complex oscillations and turbulent patterns, both mediated by ``line defects.'' Here we report the observation of such patterns in a laboratory experiment for the first time; complex spiral waves with period-2 and period-3 and turbulent patterns filled with a tangle of line defects are observed and their spatiotemporal dynamics are elucidated by line defects. Since line defect

The instability of a period-1 spiral wave resulting in a period-2 spiral wave with a line defect is investigated for the first time in a laboratory system. At the very onset the transition proceeds by an emergence of a spiraling line defect, "breathing" intermittently while retaining its symmetry of a period-1 spiral wave. With a further change in a control parameter, the line defect undergoes a meandering transition producing a compound tip trajectory, following a dynamic shape transition. The

The work function of polyaniline nanoparticles in the emeraldine base state was determined by Kelvin probe force microscopy to be ~270 meV higher than that of similar nanoparticles in the emeraldine salt state. Normal tapping mode atomic force microscopy could not be used to distinguish between the particles due to their similar morphologies and sizes. Moreover, other potential measurement systems, such as using zeta potentials, were not suitable for the measurement of surface charges of doped n