Sung Min Park

The advent of wireless micro sensors promises many yet unrealized benefits. A network of such sensors or “sensor network” introduces a new set of challenges. Besides being able to communicate effectively, sensor networks have demanding sensing tasks. First, they must be aware of their environment and oftentimes are required to adapt to their surroundings. Second, they must coordinate among them to perform a greater group-sensing task. In this context, the study of sensor networks has numerous ot

OBJECTIVE: To investigate whether virtual humans produce social facilitation effects. BACKGROUND: When people do an easy task and another person is nearby, they tend to do that task better than when they are alone. Conversely, when people do a hard task and another person is nearby, they tend to do that task less well than when they are alone. This phenomenon is referred to in the social psychology literature as social facilitation. The present study investigated whether virtual humans can evoke

We describe the system design of "Smart Kindergarten", a smart problem solving environment for early childhood education. Two crucial building blocks that make up smart kindergarten are iBadge, a lightweight power-aware sensor-instrumented badge, and Sylph, a sensor middleware infrastructure. Equipped with sensors, radio, and DSP, iBadge has been designed to be worn by kids and teachers to unobtrusively capture the interaction between the kids and their surroundings. The captured data is then wi

A 1-Gb/s differential transimpedance amplifier (TIA) is realized in a 0.25-/spl mu/m standard CMOS technology, incorporating the regulated cascode input configuration. The TIA chip is then integrated with a p-i-n photodiode on an oxidized phosphorous-silicon (OPS) substrate by employing the multichip-on-oxide (MCO) technology. The MCO TIA demonstrates 80-dB/spl Omega/ transimpedance gain, 670-MHz bandwidth for 1-pF photodiode capacitance, 0.54-/spl mu/A average input noise current, -17-dBm sensi

This paper presents an optoelectronic receiver (Rx) IC with an on-chip avalanche photodiode (APD) realized in a 0.18-μm CMOS process for the applications of home-monitoring light detection and ranging (LiDAR) sensors, where the on-chip CMOS P+/N-well APD was implemented to avoid the unwanted signal distortion from bondwires and electro-static discharge (ESD) protection diodes. Various circuit techniques are exploited in this work, such as the feedforward transimpedance amplifier for high gain, a

In this paper we introduce novel battery state aware strategies that improve the performance of battery operated systems. In our analysis, we consider the total amount of work done (or service) as the metric instead of considering just the lifetime. Based on our analysis using service curves, we formulate our static approach which generalizes many of the battery aware approaches introduced in the literatures. The results show that the static approach increases the battery utilization by 600% ove

In this paper we introduce two novel control slot scheduling approaches for creating dynamic contention free time division multiple access (TDMA) schedules. Our approaches are ideal for exchanging control information in mobile ad hoc networks (MANET) and wireless mesh networks so that dynamic resource needs of participating nodes can be rapidly accommodated for quality of service (QoS) guarantees. The two algorithms, network entry based scheduling (NEBS) and virtual slot scheduling (VSLOT), desc

Titanium and its alloys are technically superior and cost-effective materials, with a wide variety of aerospace, industrial, marine, and commercial applications. In this study, the effects of titanium ions on bacterial growth were evaluated. Six strains of bacteria known to be resistant to both metal ions and antibiotics were used in this study. Two strains, Escherichia coli ATCC 15489, and Pseudomonas aeruginosa ATCC 10145, proved to be resistant to titanium ions. Plasmid-cured P. aeruginosa re

A four-channel common-emitter (CE) transimpedance amplifier (TIA) array for optical receiver applications is studied in terms of gain, bandwidth, noise, and crosstalk between adjacent channels. The substrate crosstalk is analyzed by using a proposed lumped-element model. HSPICE simulations were conducted by using a 0.8 /spl mu/m Si/SiGe HBT technology, confirming the small signal analysis and the lumped model for crosstalk analysis. A test chip was fabricated and the measured results will be ava

This paper presents a 16-channel transimpedance amplifier (TIA) array implemented in a standard <TEX>$0.18-{\mu}m$</TEX> CMOS technology for the applications of panoramic scan LADAR (PSL) systems. Since this array is the front-end circuits of the PSL systems to recover three dimensional image for unmanned vehicles, low-noise and high-gain characteristics are necessary. Thus, we propose a voltage-mode inverter TIA (I-TIA) array in this paper, of which measured results demonstrate that each channe

This paper presents a nine-bit integrator-based time-to-digital converter (I-TDC) realized in a 180 nm CMOS technology for the applications of indoor home-monitoring light detection and ranging (LiDAR) sensors. The proposed I-TDC exploits a clock-free configuration so as to discard clock-related dynamic power consumption and some notorious issues such as skew, glitch, and synchronization. It consists of a one-dimensional (1D) flash TDC to generate coarse-control codes and an integrator with a pe

We report a derivative spectroscopic method for determining insulator-to-semiconductor transition during sol-gel metal-oxide semiconductor formation. When an as-spun sol-gel precursor film is photochemically activated and changes to semiconducting state, the light absorption characteristics of the metal-oxide film is considerable changed particularly in the ultraviolet region. As a result, a peak is generated in the first-order derivatives of light absorption (A′) vs. wavelength (λ) plots, and b

A number of gigabit transimpedance amplifiers are realized in submicron CMOS technologies. By exploiting regulated cascode (RGC) configuration for the input stage, the amplifiers efficiently isolate the large input parasitic capacitance and hence achieve significant bandwidth improvement. A 1.25-Gb/s RGC TIA demonstrates 950 MHz bandwidth for O.5 pF photodiode capacitance and the only 93 MHz difference even for 1 pF photodiode capacitance. Also, a 2.5-Gb/s RGC TIA realized in a 0.6 /spl mu/m CMO