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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of IKEEE
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Institude of Korean Electrical and Electronics Engineers
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Volume & Issues
Volume 13, Issue 4 - Dec 2009
Volume 13, Issue 3 - Sep 2009
Volume 13, Issue 2 - Jun 2009
Volume 13, Issue 1 - Mar 2009
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DFT를 사용한 고속 constant modulus algorithm 의 성능분석
Yang, Yoon-Gi ; Lee, Chang-Su ; Yang, Soo-Mi ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 1~10
Recently, some frequency domain CMA (Constant Modulus Algorithm) have been introduced in an effort to reduce computational complexities [1,2]. In , a fast algorithm that minimizing cost function designed for block input signal is employed, while in , a novel cost function that minimizing sample by sample input is used. Although, the two fast algorithm save computational complexities as compared to CMA, the convergence behaviors of the two fast algorithm show different results with repsect to CMA. Thus, in this paper, some analytical results on the error surface of the fast frequency domain CMA are introduced. From the analytical results, we show that the more recent algorithm  outperforms the previous algorithm . Simulation results reveals that the recent algorithm  shows 50% enhanced convergence with respect to the old fast algorithm . Also, we show that the recent fast algorithm  has comparable convergence performance with respect to conventional CMA algorithm.
A New PID Controller with Lyapunov Stability for Regulation Servo Systems
Lee, Jung-Hoon ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 11~18
In this paper, the stability of second order uncertain systems with regulation of PID type controllers is analyzed by using Lyapunov second method for the first time in the time domain. The property of the stability of PID regulation servo systems is revealed in sense of Lyapunov, i.e., bounded stability due to the disturbances and uncertainties. By means of the results of this stability analysis, the maximum norm bound of the error from the output without variation of the uncertainties and disturbances is determined as a function of the gains of the PID control, which make it enable to analyze the effect resulted from the variations of the disturbances and uncertainties using this norm bound for given PID gains. Using the relationship of the error from the output without variation of the uncertainties and disturbances and the PID gain with maximum bounds of the disturbances and uncertainties, the robust gain design rule is suggested so that the error from the output without the variation of the disturbances and uncertainties can be guaranteed by the prescribed specifications as the advantages of this study. The usefulness of the proposed algorithm is verified through an illustrative example.
A comparison study of input ESD protection schemes utilizing NMOS transistor and thyristor protection devices
Choi, Jin-Young ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 19~29
For two input ESD protection schemes utilizing the NMOS protection device or the lvtr_thyristor protection device, which is suitable for high-frequency CMOS ICs, we attempt an in-depth comparison study on the HBM ESD protection level in terms of lattice heating inside the protection devices and the peak voltage applied to the gate oxides in the input buffer through DC, mixed-mode transient, and AC analyses utilizing the 2-dimensional device simulator. For this purpose, we suggest a method for the equivalent circuit modeling of the input HBM test environment for the CMOS chip equipped with the input ESD protection circuit. And by executing mixed-mode simulations including up to four protection devices and analyzing the results for five different test modes, we attempt a detailed analysis on the problems which can be occurred in a real HBM test. In this procedure, we explain about the strength and weakness of the two protection schemes as an input protection circuit for high-frequency ICs, and suggest guidelines relating to the design of the protection devices.
The asymptotic tracking using variable structure control for a minimum phase nonlinear system
Oh, Seung-Rohk ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 30~35
A new controller which can achieve the asymptotic tracking is proposed for the nonlinear system having a uncertainty in the input coefficient. A high gain observer is used to estimate the state variables when the nonlinear system has a modeling uncertainty. A variable structure control is used to achieve an asymptotic tracking, while ultimate boundness was achieved in the previous work. A Lyapunov analysis is used to justify the our proposal. The performance of proposed method is demonstrated via simulation.
Development of the Adaptive Algorithm for Time Delay Systems
Lee, Soon-Young ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 36~40
In control of time delay systems, if the informations about the system model and the disturbance can be estimated exactly, the ideal response can be achieved by using Smith predictor controller. Therefore, in this paper, an adaptive algorithm is proposed to control time delay systems existing modelling errors and disturbance. An adaptive observer to estimate disturbance and system model is designed and adaptive laws adjusting the observer are proposed. The new Smith predictor controller is designed using the proposed adaptive observer. As a result, the proposed controller can eliminate the effects of the disturbance and the modelling error. The effectiveness and the improved performance of the proposed system are verified by computer simulation.
CMOS Analog-Front End for CCD Image Sensors
Kim, Dae-Jeong ; Nam, Jeong-Kwon ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 41~48
This paper describes an implementation of the analog front end (AFE) incorporated with the image signal processing (ISP) unit in the SoC, dominating the performance of the CCD image sensor system. New schemes are exploited in the high-frequency sampling to reduce the sampling uncertainty apparently as the frequency increases, in the structure for the wide-range variable gain amplifier (VGA) capable of
exponential gain control to meet the needed bandwidth and accuracy by adopting a new parasitic insensitive capacitor array. Moreover, the double cancellation of the black-level noise was efficiently achieved both in the analog and the digital domain. The proposed topology fabricated in a
CMOS process was proved in a full CCD camera system of 10-bit accuracy, dissipating 80 mA at 15 MHz with a 3.3 V supply voltage.
Supercapacitor Applications for System Stabilization and Efficiency Improvement on DC Railway System
Song, Ji-Young ; Lee, Kye-Byung ; Lee, Han-Sang ; Jang, Gil-Soo ; Kwon, Sae-Hyuk ; Lee, Chang-Mu ; Lee, Han-Min ; Kim, Gil-Dong ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 49~56
In this paper, a simulation for the stability of the catenary voltage through charging and discharging by introducing an energy storage system in the railway system and the efficient usage of restoration energy has been performed. In order for the simulation, a simple railway model with an appropriate control technique has been introduced. The catenary voltage area is divided into two areas with voltage control and an area with normal operation and current control is performed to satisfy current limit of the supercapacitor. We confirmed the energy absorption and emission through the simulation and observed energy efficiency through charging and discharging according to the operation state of the railway.
Enhancement in the photocurrent of ZnO nanoparticles by thermal annealing
Byun, Kwang-Sub ; Cho, Kyuong-Ah ; Jun, Jin-Hyung ; Seong, Ho-Jun ; Kim, Sang-Sig ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 57~64
The optoelectrical characteristics of the ZnO nanoparticles (NPs) annealed in vacuum or oxygen condition from
were examined. Increased on-off ratio (or, the ratio of photocurrent to dark current) was observed when they were annealed at
with the values enhanced about 4 orders compared to the as-prepared ZnO NPs in both annealing conditions, while the maximum efficiency was shown at the annealing temperature of
for the ZnO NPs annealed in vacuum with the value of 29.8 mA/W and at the temperature of
for those annealed in oxygen condition with the value of 40.3 mA/W. Photoresponse behavior of the ZnO NPs annealed in oxygen showed the sharp increase right after the ir exposure to the light followed by the slow decay and saturation during steady illumination, differing from the ZnO NPs annealed in vacuum which only exhibited the gradual increase. This difference occurred due to the curing effect of the oxygen vacancies. SEM images indicated no change in their morphologies with annealing, indicating the change in their internal structures by annealing, and most remarkably at
. As for their photoluminescence(PL) spectra, the decrease of the deep-level(DL) emission was observed when they were annealed in oxygen at
, and not at
10 GHz Multiuser Optical CDMA Based on Spectral Phase Coding of Short Pulses
Ruan, Wan-Yong ; Won, In-Jae ; Park, Jae-Hyun ; Seo, Dong-Sun ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 65~70
We propose an ultrashort pulse optical code-division multiple-access (O-CDMA) scheme based on a pseudorandom binary M-sequence spectral phase encoding and decoding of coherent mode-locked laser pulses and perform a numerical simulation to analyze its feasibility. We demonstrate the ability to properly decode any of the multiple (eight) 10 Gbit/s users by the matched code selection of the spectral phase decoder. The peak power signal to noise ratio of properly and improperly decoded
signals could be greater than 15 for 127 M-sequence coding.
Energy-efficient Positioning of Cluster Heads in Wireless Sensor Networks
Sohn, Surg-Won ; Han, Kwang-Rok ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 71~76
As one of the most important requirements for wireless sensor networks, prolonging network lifetime can be realized by minimizing energy consumption in cluster heads as well as sensor nodes. While most of the previous researches have focused on the energy of sensor nodes, we devote our attention to cluster heads because they are most dominant source of power consumption in the cluster-based sensor networks. Therefore, we seek to minimize energy consumption by minimizing the maximum(MINMAX) energy dissipation at each cluster heads. This work requires energy-efficient clustering of the sensor nodes while satisfying given energy constraints. In this paper, we present a constraint satisfaction modeling of cluster-based routing in a heterogeneous sensor networks because mixed integer programming cannot provide solutions to this MINMAX problem. Computational experiments show that substantial energy savings can be obtained with the MINMAX algorithm in comparison with a minimum total energy(MTE) strategy.
Low-Power ECG Detector and ADC for Implantable Cardiac Pacemakers
Min, Young-Jae ; Kim, Tae-Geun ; Kim, Soo-Won ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 77~86
A wavelet Electrocardiogram(ECG) detector and its analog-to-digital converter(ADC) for low-power implantable cardiac pacemakers are presented in this paper. The proposed wavelet-based ECG detector consists of a wavelet decomposer with wavelet filter banks, a QRS complex detector of hypothesis testing with wavelet-demodulated ECG signals, and a noise detector with zero-crossing points. To achieve high-detection performance with low-power consumption, the multi-scaled product algorithm and soft-threshold algorithm are efficiently exploited. To further reduce the power dissipation, a low-power ADC, which is based on a Successive Approximation Register(SAR) architecture with an on/off-time controlled comparator and passive sample and hold, is also presented. Our algorithmic and architectural level approaches are implemented and fabricated in standard
CMOS technology. The testchip shows a good detection accuracy of 99.32% and very low-power consumption of
with 3-V supply voltage.
The novel SCR-based ESD Protection Device with High Holding Voltage
Won, Jong-Il ; Koo, Yong-Seo ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 87~93
The paper introduces a silicon controlled rectifier (SCR)-based device with high holding voltage for ESD power clamp. The holding voltage can be increased by extending a p+ cathode to the first n-well and adding second n-well wrapping around n+ cathode. The increase of the holding voltage above the supply voltage enables latch-up immune normal operation. In this study, the proposed device has been simulated using synopsys TCAD simulator for electrical characteristic, temperature characteristic, and ESD robustness. In the simulation result, the proposed device has holding voltage of 3.6V and trigger voltage of 10.5V. And it is confirmed that the device could have holding voltage of above 4V with the size variation of extended p+ cathode and additional n-well.
An adaptive MAC protocol exploiting multiple paths in wireless mesh networks
Lee, Hyung-Keun ; Yi, Joon-Hwan ;
Journal of IKEEE, volume 13, issue 1, 2009, Pages 94~100
In recent years, the wireless mesh network (WMN) has been an emerging technology to provide Internet access to fixed and mobile wireless devices. The main goal of this paper is the design and simulation of a new MAC protocol based on the multi-path routing information for wireless mesh networks. The information about multiple paths discovered in the network layer is exploited by the MAC layer in order to forward a frame over the best hop out of multiple hop choices. The performance of our approach is compared with conventional 802.11 MAC through the simulation. The results show that our scheme exhibits a significantly better performance rather than conventional 802.11 MAC protocol in terms of packet overhead, end-to-end throughput and delay.