• Journal of the Korea Society of Computer and Information
• /
• v.19 no.12
• /
• pp.133-141
• /
• 2014

An efficient method for reducing power consumption in pipelined deep packet inspection systems is proposed. It is based on the observation that the number of memory accesses is dominant for the power consumption and the number of accesses drops drastically as the input goes through stages of the pipelined AC-DFA. A DPI system is implemented where the operating frequency of the stages that are not frequently used in the pipeline is reduced to eliminate the waste of power consumption. The power consumption of the proposed DPI system is measured upon various input character set and up to 25% of reduction of total power consumption is obtained, compared to those of the recent DPI systems. The method can be easily applied to other pipelined architecture and string searching applications.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.2
• /
• pp.304-309
• /
• 2015

Applicable range of Photoplethysmography (PPG) becomes wider as a non-invasive physiological measurement technique. However, PPG waveform is easy to be distorted by ambient light or vascular variation from temperature changes. Especially, irregular variation of PPG waveform caused by ambient temperature not only severely distorts the PPG, but also leads miss interpretation in clinical applications. Therefore, the investigation of between temperature and PPG waveform is quite important in using PPG. The purpose of this research is to quantify the PPG waveform characteristic and to investigate the waveform variation following the temperature change on measuring site. To quantify the fluctuation of PPG waveform, we use two techniques; detrended fluctuation analysis (DFA) and AC/DC analysis of PPG. We record PPG under temperature stress, which applied by medical use heat pack ($40^{\circ}C$) and ice pack ($0^{\circ}C$). Ten participants were applied to the experiment, and the result was evaluated to approve the temperature effect with statistical method, Wilcoxon signed rank test. The result shows that the AC component (p<0.05) and perfusion index DFS scale exponent (p<0.01) of PPG have the significance to temperature stress except for a DC component of PPG.