조성환 교수

Emerging distributed wireless microsensor networks will enable the reliable and fault tolerant monitoring of the environment. Such microsensors are required to operate for years from a small energy source, while maintaining a reliable communication link to the base station. The design of energy-aware communication protocols can have a dramatic impact on the network lifetime for such applications. A detailed communication energy model, obtained from measurements, is introduced that incorporates t

A 6.5-GHz FSK modulator suitable for low power wireless sensor network is presented. The energy efficient modulator employs closed-loop direct VCO modulation to achieve high data rate, multistage variable loop bandwidth technique for fast startup time and /spl Sigma/-/spl Delta/ for reduced power consumption in the synthesizer with fine resolution in frequency channel selection. The modulator, implemented using 0.25-/spl mu/m CMOS, achieves 20-/spl mu/s startup time with an effective data rate o

The purpose of this paper is to improve scientific attitude and interest of the elementary school students by using STEAM-based robots in education. In this work, we analyzed PDIE model that describes methodology for generating STEAM integrated education materials and then we also developed teaching materials utilizing STEAM-based robots. The effect of the STEM-based robots in education was analyzed through a test class which demonstrated the robots indeed help improving scientific attitude and

The debonding distress in asphalt pavement structures is a critical problem that affects the performance of asphalt concrete pavements. It occurs at the layer interface due to the poor bond quality between adjacent asphalt concrete layers and/or when stresses at the layer interface exceed the strengths of the material at the interface. The debonding of the adjacent layers, especially the top surface layer of an asphalt pavement, is a contributing factor to the premature cracking of pavements. He

A 6.5 GHz FSK modulator suitable for low power wireless sensor network is presented. The modulator employs closed loop direct VCO modulation to achieve high data rate, variable loop bandwidth technique for fast start-up rates and /spl Sigma/-/spl Delta/ for reduced power consumption in the divider with fine resolution in channel selection. The synthesizer, implemented in 0.25 /spl mu/m CMOS, achieves 20 /spl mu/s start-up time with an effective data rate of 2.5 Mbps while consuming 22 mW.

Increasing the lifetime of wireless sensors is essential for the proliferation of wireless sensor networks in various environments. In this paper, the relationship between bandwidth and energy consumption is exploited to increase the lifetime of the sensors. A variable bandwidth allocation scheme that uses time-frequency slot assignment is proposed to reduce the energy consumption of a collaborative sensor network which has large spatial variation in node density and event rates. To assign the t

Asphalt pavement structures are composed of different asphalt concrete layers with surface layers that are bonded together with a tack coat. Thus, interlayer bonding between pavement layers is a key factor that affects the performance of any pavement structure. However, relatively little attention has been given to the characterization and modeling of interlayer bonding or to associated test methods that can be used in the laboratory to evaluate the bond strength between asphalt concrete layers.

The effective structural number (SNeff) determined from the falling weight deflectometer (FWD) has been widely used for pavement structural evaluations. In Indiana, the AASHTO 1993 method is currently used to determine SNeff, but it was found to be inaccurate for full-depth asphalt pavements. Thus, this study developed an enhanced model to more accurately estimate SNeff of full-depth asphalt pavements. The AASHTO 1993 method and the Rohde model tend to overestimate the SNeff, and the Rohde model

A data driven variable length decoder chip is presented which exploits the signal statistics of variable length codes to reduce power. The approach uses fine grain lookup table partitioning to reduce switched capacitance based on codeword frequency. The variable length decoder for MPEG-2 has been fabricated and consumes 530 /spl mu/W at 1.35 V for a video rate of 48M DCT samples/sec using a 0.6 /spl mu/m CMOS technology. More than an order magnitude of power reduction is demonstrated without per

There is a critical vulnerability in the 5G AKA protocol of the 3GPP. We propose a protocol that compensates for these vulnerabilities and speed up the existing protocol; and the study implements this protocol to experiment with the vulnerabilities. The protocol uses the Light-weight Encryption Algorithm and is expected to be n3 times faster in than with the application of Advanced Encryption Standard algorithms. By using this algorithm, we improve the protocol efficiently, reduced the power con

PURPOSES : The first generation of wide base tires introduced in the early 1980s was found to cause a significant increase in pavement damage compared to dual-tire assemblies. However, wide base tires have evolved considerably, and a new generation of wide base tire is thought to be comparable to conventional dual tires for pavement damage. A challenge associated with using wide base tires is the accurate quantification of pavement damage induced by these tires. The objective of this study was t