Bong-Ki Lee

Peak power reduction methodology for multi-core systems

In this paper, we propose the task scheduling for preventing the occurrence of peak power in the multi-core systems considering data dependence. In the mobile system, the peak power reduces the battery lifetime and makes the system unstable. Among the power consumption of system, the proportion of power consumption of core is very large. If cores execute multiple tasks simultaneously, this gives rise to the peak power. Therefore, algorithm to minimize the occurrence of peak power is needed. When multiple tasks are allocated to the multi-core systems, data dependence relations of all tasks should be considered to avoid data interferences. The proposed algorithm to reduce the peak power schedules the tasks with the data dependence information after data dependence analysis. The proposed algorithm is composed of task partitioning step, data dependence analysis step and priority scheduling step. The simulation results show that the proposed algorithm reduce the occurrence of peak power by up to around 11% compared to the existing algorithms.

Packet loss concealment based on deep neural networks for digital speech transmission

In this paper, we propose the regression-based packet loss concealment (PLC) for digital speech transmission by using deep neural networks (DNNs) with a multiple-layer deep architecture. For the DNN training, log-power spectra and phases are employed as features in the input layer for the large training set, which ensures non-linear mapping the frames from the last correctly received frame to the missing frame. Once the training is accomplished by the restricted Boltzmann machine (RBM)-based pre-training to initialize the DNN, minimum mean square error (MMSE)-based fine tuning is then performed based on the back-propagation algorithm. In the reconstruction stage, the trained DNN model is fed with the features of the previous frames in order to estimate the log-power spectra and phases of the missing frames. Reconstruction is further improved by using the cross-fading technique to mitigate discontinuity between the reconstruction signal and good frame signal in the time-domain. To demonstrate the performance of the proposed algorithm, hidden Markov model (HMM)-based PLC algorithm and the PLC algorithm standardized in adaptive multi-rate wideband (AMR-WB) Appendix I were used for comparison. The experimental results show that the proposed approach provides better speech quality and speech recognition accuracy than the conventional approaches.

Thermal aware timing budget for buffer insertion in early stage of physical design

Thermal generation by power dissipation of the highly integrated System on Chip (SoC) device is irregularly distributed on the intra chip. It leads to thermal increment of the each thermally different region and effects on the propagation timing; consequently, the timing violation occurs due to the misestimated number of buffers. In this paper, the timing budgeting methodology which contains the estimated thermal distribution on a chip in the early stage of physical design by modeled the RC delay considering temperature and buffer insertion planning using by the proposed delay model are presented. Simulation results showed the reduction of the worst delay after buffer insertion up to 30% in contrast to the buffer insertion without considering temperature.

A novel methodology for power delivery network optimization in 3-D ICs using through-silicon-via technology

Three-dimensional integrated circuits (3-D IC) are available through the die-stacking and through-silicon-via (TSV) technologies. The 3-D IC using the TSV brings the performance improvement through the minimization of wire length and footprint area. However, the 3-D ICs have many challenges for power delivery network design due to larger supply currents and longer power delivery paths compared to 2-D ICs. The power delivery network in 3-D IC with flip chip package is largely composed of power/ground (P/G) bumps and P/G TSVs. Because the number of P/G bumps is limited and the size of P/G TSV is larger than that of standard cell, it is important to optimize the P/G bumps and P/G TSVs together while satisfying the IR-drop constraint. In this paper, we investigated an effect of the number of power bumps and power TSVs on the IR-drop in 3-D IC floorplan level and proposed the methodology that reduces the number of power bumps by 88.25% on average while the number of power TSVs and maximum IR-drop are comparable to the previous methodology.

An experimental study: The sufficient respiration rate detection technique via continuous wave Doppler radar

In this paper, we present the experimental study based on filtering techniques to extract essential vital signals such respiration rate (RR) using continuous wave (CW) Doppler radar sensor. Due to the fact that the CW Doppler radar offers very high sensitivity towards minor movements, based on this technology, various filtering techniques were introduced and the detection rate was compared to the reference devices to conclude the leading method for the respiration rate detection.