• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.5
• /
• pp.998-1004
• /
• 2016

This paper investigates a new sensorless control appling a virtual flux oriented vector control without the line voltage sensor for the power factor correction of 3 phase PWM converter. The DC output voltage is controlled by applying the kalman filter algorithm for the virtual flux estimation and the synchronous phase is obtained by using the estimated virtual flux equation based on kalman filter. This method is used to reduce the calculation time of the system and obtain a stable control that the input current including the harmonics and the noise is improved. The proposed system implement PFC algorithm in the variable region of DC output voltage. It can obtain the unity power factor, and can precisely control the DC output voltage in the load variation and in the variable voltage range. The performance of the proposed algorithm is verified through simulation and experiment.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.6
• /
• pp.1495-1507
• /
• 1997

Among a number of approaches to text compression, adaptive dictionary schemes based on a sliding window have been very frequently used due to their high performance. The LZ77 algorithm is the most efficient algorithm which implements such adaptive schemes for the practical use of text compression. This paperpresents a VLSI architecture designed for processing the LZ77 algorithm in parallel. Compared with the other VLSI architectures developed so far, the proposed architecture provides the more viable solution to high performance with regard to its throughput, efficient implementation of the VLSI systolic arrays, and hardware scalability. Indeed, without being affected by the size of the sliding window, our system has the complexity of O(N) for both the compression and decompression and also requires small wafer area, where N is the size of the input text.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.1
• /
• pp.225-231
• /
• 2013

In this study, we propose the design of optimized pRBFNNs-based night vision face recognition system using PCA algorithm. It is difficalt to obtain images using CCD camera due to low brightness under surround condition without lighting. The quality of the images distorted by low illuminance is improved by using night vision camera and histogram equalization. Ada-Boost algorithm also is used for the detection of face image between face and non-face image area. The dimension of the obtained image data is reduced to low dimension using PCA method. Also we introduce the pRBFNNs as recognition module. The proposed pRBFNNs consists of three functional modules such as the condition part, the conclusion part, and the inference part. In the condition part of fuzzy rules, input space is partitioned by using Fuzzy C-Means clustering. In the conclusion part of rules, the connection weights of pRBFNNs is represented as three kinds of polynomials such as linear, quadratic, and modified quadratic. The essential design parameters of the networks are optimized by means of Differential Evolution.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.05a
• /
• pp.681-684
• /
• 2015

Power amplifier is an essential component for transmitting signals to a remote receiver in wireless communication systems. Power amplifier is a non-linear device in general, and the nonlinear distortion becomes severer as the output power increases. The nonlinearity results in spectral regrowth, which leads to adjacent channel interference, and decreases the transmit signal quality. To linearize power amplifiers, many techniques have been developed so far. Among the techniques, digital pre-distortion is known as the most cost and performance effective technique. However, the linearization performance falls down abruptly when the power amplifier operates in its saturation region. This is because of the severe nonlinearity. To relieve this problem, this paper proposes a new adaptive predistortion technique. The proposed technique controls the adaptive algorithm based on the power amplifier input level. Specifically, for small signals, the adaptive predistortion algorithm works normally. On the contrary, for large signals, the adaptive algorithm stops until small signals occur again. By doing this, wrong coefficient update by severe nonlinearity can be avoided. Computer simulation results show that the proposed method can improve the linearization performance compared with the conventional digital predistortion algorithms.

• The Transactions of the Korea Information Processing Society
• /
• v.3 no.5
• /
• pp.1281-1293
• /
• 1996

In this paper, we propose a novel recognition model of on-line cursive Korean characters using HMM(Hidden Markov Model) and level building algorithm. The model is constructed as a form of recognition network with HMM for graphemes and Korean combination rules. Though the network is so flexible as to accomodate variability of input patterns, it has a problem of recognition speed caused by 11, 172 search paths. To settle the problem, we modify the level building algorithm to be adapted directly to the Korean combination rules and apply it to the model. The modified algorithm is efficient network search procedure time complexity of which depends on the number of HMMs for each grapheme, not the number of paths in the extensive recognition network. A test with 15, 000 hand written characters shows recognition rat 90% and speed of 0.72 second per character.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.8
• /
• pp.2473-2483
• /
• 2000

In this paper, The turbo code is used to effectively remove noise which is generated on the image communication channel. Turbo code had excellent decoding performance. However, it had limitations for real time communication because of the system complexity and time delay in decoding procedure. To overcome this problem, this paper proposed a new SRI(Semi Random Interleaved algorithm, which decrease the time delay, when the image data, which reduced the interleaver size of turbo code encoder and decoder, transmitted. The SRI algorithm was composed of 0.5 interleaver size from input frame sequence. When the data inputs in interleaver, the data recorded by row such as block interleaver. But, When the data read in interleaver, the data was read by randomly and the next data located by the just address simultaneously. Therefore, the SRI reduced half-complexity when it was compared with pre-existing method such as block, helical, random interleaver. The image data could be the real time processing when the SRI applied to turbo code.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.49 no.4
• /
• pp.16-22
• /
• 2012

In this paper, we present spiral pattern which suits for optical simulator to calibrate fisheye lens and compensate geometric distortion. Using spiral pattern, we present calibration without mathematical modeling in advance. Proposed spiral pattern used to input image of optical simulator. Using fisheye lens image, we calibrate a fisheye lens by matching geometrically moved dots to corresponding original dots which leads not to need mathematical modeling. Proposed algorithm calibrates using dot matching which matches spiral pattern image dot to distorted image dot. And this algorithm does not need modeling in advance so it is effective. Proposed algorithm is enabled at processing of pattern recognition which has to get the exact information using fisheye lens for digital zooming. And this makes possible at compensation of geometric distortion and calibration of fisheye lens image applying in various image processing.

• Journal of the Korea Society of Computer and Information
• /
• v.10 no.2 s.34
• /
• pp.49-57
• /
• 2005

In this paper. a CLB-based CPLD low power technology mapping algorithm for trade-off is proposed. To perform low power technology mapping for CPLD, a given Boolean network has to be represented to DAG. The proposed algorithm consists of three step. In the first step, TD(Transition Density) calculation have to be Performed. Total power consumption is obtained by calculating switching activity of each nodes in a DAG. In the second step, the feasible clusters are generated by considering the following conditions : the number of output. the number of input and the number of OR-terms for CLB within a CPLD. The common node cluster merging method, the node separation method, and the node duplication method are used to produce the feasible clusters. The proposed algorithm is examined by using benchmarks in SIS. In the case that the number of OR-terms is 5, the experiments results show reduction in the power consumption by 30.73$\%$ comparing with that of TEMPLA, and 17.11$\%$ comparing with that of PLAmap respectively

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.8
• /
• pp.3-9
• /
• 2015

Under the maximum transmit power constraint and the minimum rate constraint, we propose the optimal number of transmit antennas and transmit power which maximize energy-efficiency (EE) in multi-user multiple-input multiple-output (MIMO) downlink system with the maximal ratio transmission (MRT) precoding. Because the optimization problem for the instantaneous channel is difficult to solve, we use independence of individual channel, average channel gain and path loss to approximate the objective function. Since the approximated EE optimization problem is two-dimensional search problem, we find the optimal number of transmit antennas and transmit power using Lagrange multipliers and our proposed algorithm. Simulation results show that the number of transmit antennas and power obtained by proposed algorithm are almost identical to the value by the exhaustive search.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.24 no.2
• /
• pp.141-146
• /
• 2014

This paper suggests a way of generating one-day load curves for performance improvement of peak shaving in a power system. This Peak Shaving algorithm is a long-term scheduling algorithm of PMS (Power Management System) for BESS (Battery Energy Storage System). The main purpose of a PMS is to manage the input and output power from battery modules placed in a power system. Generally, when a Peak Shaving algorithm is used, a difference occurs between predict load curves and real load curves. This paper suggests a way of minimizing the difference by making predict load curves that consider weekly normalization and seasonal load characteristics for smooth energy charging and discharging.