• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.136-142
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• 2013

CRC features have been added to increase the reliability of the data in memory products for high-speed operation, such as DDR4. High-speed memory products in a shortage of internal timing margin increases for the CRC calculation. Because the existing CRC requires many additional circuit area and delay time. In this paper, we show that the matrix-type CRC and a new XOR/XNOR gate could be improved the circuit area and delay time. Proposed matrix-type CRC can detect all odd-bit errors and can detect even number of bit errors, except for multiples of four bits. In addition, a single error in the error correction can reduce the burden of re-transmission of data between memory products and systems due to CRC errors. In addition, the additional circuit area, compared to existing methods can be improved by 57%. The proposed XOR gate which is consists of six transistors, it can reduce the area overhead of 35% compared to the existing CRC, 50% of the gate delay can be reduced.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.1
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• pp.13-20
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• 2005

This paper addresses a new blind channel equalization method using fourth-order cumulants of channel inputs and a three-layer neural network equalizer. The proposed algorithm is robust with respect to the existence of heavy Gaussian noise in a channel and does not require the minimum-phase characteristic of the channel. The transmitted signals at the receiver are over-sampled to ensure the channel described by a full-column rank matrix. It changes a single-input/single-output (SISO) finite-impulse response (FIR) channel to a single-input/multi-output (SIMO) channel. Based on the properties of the fourth-order cumulants of the over-sampled channel inputs, the iterative algorithm is derived to estimate the deconvolution matrix which makes the overall transfer matrix transparent, i.e., it can be reduced to the identity matrix by simple recordering and scaling. By using this estimated deconvolution matrix, which is the inverse of the over-sampled unknown channel, a three-layer neural network equalizer is implemented at the receiver. In simulation studies, the stochastic version of the proposed algorithm is tested with three-ray multi-path channels for on-line operation, and its performance is compared with a method based on conventional second-order statistics. Relatively good results, withe fast convergence speed, are achieved, even when the transmitted symbols are significantly corrupted with Gaussian noise.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.9
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• pp.1081-1087
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• 1999

Load Flow calulation methods can usually be divided into Gauss-Seidel method, Newton-Raphson method and decoupled method. Load flow calculation is a basic on-line or off-line process for power system planning. operation, control and state analysis. These days Newton-Raphson method is mainly used since it shows remarkable convergence characteristics. It, however, needs considerable calculation time in construction and calculation of inverse Jacobian matrix. In addition to that, Newton-Raphson method tends to fail to converge when system loading is heavy and system has a large R/X ratio. In this paper, matrix equation is used to make algebraic expression and then to slove load flow equation and to modify above defects. And it preserve P-Q bus part of Jacobian matrix to shorten computing time. Application of mentioned algorithm to 14 bus, 39 bus, 118 bus systems led to identical results and the same numbers of iteration obtained by Newton-Raphson method. The effect of computing time reduction showed about 28% , 30% , at each case of 39 bus, 118 bus system.

• Journal of the Optical Society of Korea
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• v.10 no.1
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• pp.11-15
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• 2006

We have proposed and theoretically verified an optical regenerator using a single semi-reflective semiconductor optical amplifier (SR-SOA). To explain the operation characteristics and the operation condition of the proposed opticalregenerator, the simplified gain model for the SR-SOA is introduced and confirmed by comparing the result of the SOA simulation based on the transfer matrix method (TMM). The simulation results show that both extinction ratio (ER) enhancement and signal amplification can be achieved in the proposed regenerator.

• Journal of Biosystems Engineering
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• v.27 no.6
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• pp.529-536
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• 2002

The performance of stilting engine, in particular, its energy conversion efficiencies are critically influenced by the regenerator characteristics. The regenerator characteristics are influenced by effectiveness, void fraction. heat transfer loss and fluid friction loss in the regenerator matrix. These factors were influenced by the surface geometry and material properties of the regenerator matrix. The regenerator design goals arc good heat transfer and low pressure drop of working Bas across the regenerator. Various data for designing a wire screen matrix have been given by Kays and London(1984). The mesh number of their experiment. however, was confined below the No. 60. which seems rather small for the Stirling engine applications. In this paper. in order to provide a basic data for the design of regenerator matrix, characteristics of heat transfer and flow friction loss were investigated by a packed mettled of matrix in oscillating flow as the same condition of operation in a Stirling engine. Seven kinds of sing1e wire screen meshes were used as the regenerator matrices. The results are summarized as follows; 1. While the working fluid flew slowly in the regenerator. the temperature difference was great at the both hot-blow(the working fluid flows from healer to cooler) and cold-blow(the working fluid flows from cooler to healer). On the other hand. while the working fluid flew fast. the temperature difference was not distinguished. 2. The No.150 wire screen used as the regenerator matrix showed excellent performance than tile others. 3. Phase angle variation and filling rate affected heat transfer or regenerator matrices. 4. Temperature difference between the inlet and outlet of the regenerator is very hish in degree of 120 phase angle.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1552-1557
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• 2015

The paper unleashes a new idea to arrive at reduced switch count topological structures configured in the form of a matrix for a cascaded Multi level inverter (CMLI). The theory encircles to minimize the number of switches involved in the conduction path and there from acclaim reduced input current distortion, lower switching losses and electromagnetic interference. The focus extends to standardize the number of power devices required for reaching different levels of output voltage from the same architecture. It includes appropriate pulse width modulation (PWM) strategy to generate firing pulses and ensure the desired operation of the power modules. The investigative study carries with it MATLAB based simulation and experimental results obtained using suitable prototypes to illustrate the viability of the proposed concept. The promising nature of the performance projects a new dimension in the use of single phase MLIs for renewable energy related applications.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.1
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• pp.34-40
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• 1998

Conductive metal matrix composite(MMC) material of 30% silicon carbide particulated based on aluminum matrix was machined by die sinking electrical discharge machining(EDM) process according to different current and duty factor for reverse polarity of electrode. Material removal rate(MRR) was examined by process under various operation conditions. The surface morphology was evaluated by surface roughness parameter and scanning electron microscopy(SEM) research. The MRR was suddenly increased over 11 ampere of current, and it was slightly changed over 0.3 of duty factor. The maximum surface roughness of EDMed surface was affected by the duty factor. The SEM photograghs of EDMed surface showed wide recast distribution region of melting materials as increased of current and duty factor.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.97-104
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• 2018

This paper proposes supplementary control of conventional coordinated control of a power plant which directly affects network frequency. The supplementary control with dynamic matrix control is applied for 1000 MW power plant with ultra-supercritical (USC) once-through boiler. The supplementary control signal is added to the boiler feedforward signal in the existing coordinated control logic. Therefore, it is a very practical structure that can maintain the existing multi-loop control system. This supplementary controller uses the step response model for the power plant system, and on-line optimization is performed at every sampling step. The simulation results demonstrate the effectiveness of the proposed supplementary control in a wide operating range of a practical 1000 MW USC power plant simulator. These results can contribute the stable operation of power system frequency.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.4
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• pp.447-453
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• 2013

Compensating characteristics of a voltage sag/swell compensator utilizing single-phase matrix converter is examined. First, system configuration and operation for both voltage sag and swell are described. Next, in order to suppress pulsations of the source voltage, a countermeasure using low pass filter and all pass filter is introduced. Then, compensating characteristics of the compensator are investigated for R-L load by simulation. Finally, the validity of the simulated results is confirmed by the experimental results.

• Journal of Surface Science and Engineering
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• v.29 no.4
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• pp.229-237
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• 1996

Porous matrices for PAFC were prepared with chemically synthesized polyaniline powders. Phosphoric acid doped polyaniline showed decreasing electric conductivities as the temperature increased. Above $100^{\circ}C$, it showed negligible conductivities. It was stable in phosphoric acid up to $250^{\circ}C$. SiC powders or SiC whiskers were added to polyaniline to decrease the thermal expansion of polyaniline. 10% of polytetrafluoroethylene(PTFE) was also added as a binder. The bubble pressures and wettabilities of matrices were investigated and compared with the porosities measured by porosimeter. Based on these data, the optimum manufacturing condition was determined. The bubble pressure of the matrix made by adding 25w/o SiC whiskers was 345mmHg, the wettability was 235w/o, and the porosity was 83%. In the unit cell operation, the performances of polyaniline matrices were as good as those of SiC matrices. This result suggested that polyaniline can be a possible candidate for the matrix material of PAFC.