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  • Title/Summary/Keyword: Input-output method

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An Efficient User Selection Algorithm in Downlink Multiuser MIMO Systems with Zero-Forcing Beamforming (하향링크 다중 사용자 MIMO 시스템에서의 Zero-Forcing 빔 형성을 이용한 효과적인 사용자 선택 기법)

  • Go, Hyun-Sung;Oh, Tae-Youl;Choi, Seung-Won
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.6A
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    • pp.494-499
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    • 2009
  • In this paper, we provide an efficient method of user selection for achieving the maximum system throughput in downlink multiuser Multiple-Input Multiple-Output (MIMO) systems. A proposed method is for selecting a fine user set only with powers of each user channel and angles between them. This algorithm is simpler than SUS because there is no considering about the optimal value of correlation. The proposed method finds the user set toward maximizing system throughput, so it has high performance.

Reducing Current Distortion in Indirect Matrix Converters Operating in Boost Mode under Unbalanced Input Conditions

  • Choi, Dongho;Bak, Yeongsu;Lee, Kyo-Beum
    • Journal of Power Electronics
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    • v.19 no.5
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    • pp.1142-1152
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    • 2019
  • This paper presents a control method for reducing the current distortion in an indirect matrix converter (IMC) operating in boost mode under unbalanced input conditions. IMCs operating in boost mode are useful in distributed generation (DG) systems. They are connected with renewable energy systems (RESs) and the grid to transmit the power generated by the RES. However, under unbalanced voltage conditions of the RES, which is connected with the input stage of the IMC operating in boost mode, the input-output currents are distorted. In particular, the output current distortions cause a ripple of the power, which is transferred to the grid. This aggravates the reliability and stability of the DG system. Therefore, in this paper, a control method using positive/negative sequence voltages and currents is proposed for reducing the current distortion of both side in IMCs operating in boost mode. Simulation and experimental results have been presented to validate effectiveness of the proposed control method.

Digital Control Strategy for Input-Series-Output-Parallel Modular DC/DC Converters

  • Sha, Deshang;Guo, Zhiqiang;Liao, Xiaozhong
    • Journal of Power Electronics
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    • v.10 no.3
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    • pp.245-250
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    • 2010
  • Input-series-output-parallel (ISOP) converters consisting of multiple modular DC/DC converters can enable low voltage rating switches to be used under high voltage input applications. This paper presents a digital control strategy, which can achieve equal sharing of input voltage for a modular ISOP system consisting of two-transistor forward DC/DC converters by forcing the input voltages of neighboring modules to be equal. The proposed scheme is analyzed using small signals analysis based on the state space average method. The performance of the proposed control strategy is verified with an experimental prototype of an ISOP converter made up of three two-switch forward converters.

Modeling and Optimization of RMS Pulse Width for Transmission in Dispersive Nonlinear Fibers

  • Lee, Jong-Hyung
    • Journal of the Optical Society of Korea
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    • v.7 no.4
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    • pp.258-263
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    • 2003
  • Simple algebraic expressions are derived to approximate the optimal input RMS pulse width and the resulting output RMS pulse width in single-mode fibers. The results are compared with the previously published methods and with numerical results by the split-step Fourier method. In addition, for a transform-limited Gaussian input pulse, it is shown that there is no optimum input pulse width to minimize the output spectrum width. Finally, with fiber nonlinearity, it is shown mathematically that there is not an optimum input pulse width to minimize the product,σtσω, which is inversely proportional to the transmission capacity of WDM systems.

A Fuzzy Logical Optimal Efficiency Control of Permanent Magnet Synchronous Motor (PMSM의 퍼지 로직 최적 효율 제어)

  • Zhou, Guang-Xu;Lee, Dong-Hee;Ahm, Jin-Woo
    • Proceedings of the KIEE Conference
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    • 2007.04c
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    • pp.97-99
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    • 2007
  • This paper presents a fuzzy logical control method to implement an on-line optimum efficiency control for Permanent Magnet Synchronous Motor. This method real-timely adjusts the output voltage of the inverter system to achieve the optimum running efficiency of the whole system. At first, the input power is calculated during the steady state in the process of efficiency optimizing. To exactly estimate the steady state of the system, this section needs check up the speed setting on timely. The second section is to calculate input power of dc-bus. The exact measurement of the voltage and current is the vital point to acquire the input power. The third section is the fuzzy logic control unit, which is the key of the whole drive system. Based on the change of input power of dc-bus and output voltage, the variable of output voltage is gained by the fuzzy logical unit. With the on-line optimizing. the whole system call fulfill the minimum input power of dc-bus on the running state. The experimental result proves that the system applied the adjustable V/f control method and the efficiency-optimizing unit possesses optimum efficiency, and it is a better choice for simple variable speed applications such as fans and pump.

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A Study on Space Vector Modulation Method to Improve Input Power Factor of Matrix Converter (매트릭스 컨버터의 입력 역률 향상을 위한 공간벡터변조기법에 관한 연구)

  • Nguyen, Hoang M.;Lee, Hong-Hee;Chun, Tae-Won
    • The Transactions of the Korean Institute of Power Electronics
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    • v.13 no.6
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    • pp.476-486
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    • 2008
  • It is very important to design the input filter optimally in matrix converters. But, the input power factor is deteriorated in spite of the optimal filter design due to the existence of inductor and capacitor included in the filter, and it is hard to keep high power factor in the whole operating range which is one of the major advantages of the matrix converters because the power factor is changed according to the output frequency and the load current. In this paper, we introduce the new space vector modulation method which can preserve the input power factor almost unity even though the output load or the output frequency is varied. It is also presented how to implement the proposed method effectively.

Discrete-Time Output Feedback Algorithm for State Consensus of Multi-Agent Systems (다 개체 시스템의 상태 일치를 위한 이산 시간 출력 궤환 협조 제어 알고리즘)

  • Kim, Jae-Yong;Lee, Jin-Young;Kim, Jung-Su
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.3
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    • pp.625-631
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    • 2011
  • This paper presents a discrete-time output feedback consensus algorithm for Multi-Agent Systems (MAS). Under the assumption that an agent is aware of the relative state information about its neighbors, a state feedback consensus algorithm is designed based on Linear Matrix Inequality (LMI) method. In general, however, it is possible to obtain its relative output information rather than the relative state information. To reconcile this problem, an Unknown Input Observer (UIO) is employed in this paper. To this end, first it is shown that the relative state information can be estimated using the UIO and the measured relative output information. Then a certainty-equivalence type output feedback consensus algorithm is proposed by combining the LMI-based state feedback consensus algorithm with the UIO. Finally, simulation results are given to illustrate that the proposed method successfully achieves the state consensus.

Indentification of continuous systems in the presence of input-output measurement noises

  • Yang, Zi-Jiang;Sagara, Setsuo;Wada, Kiyoshi
    • 제어로봇시스템학회:학술대회논문집
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    • 1990.10b
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    • pp.1222-1227
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    • 1990
  • The problem of identification of continuous systems is considered when both the discrete input and output measurements are contaminated by white noises. Using a predesigned digital low-pass filter, a discrete-time estimation model is constructed easily without direct approximations of system signal derivatives from sampled data. If the pass-band of the filter is designed so that it includes the main frequencies of both the system input and output signals in some range, the noise effects are sufficiently reduced, accurate estimates can be obtained by least squares(LS) algorithm in the presence of low measurement noises. Two classes of filters(infinite impulse response(IIR) filter and finite impulse response(FIR) filter) are employed. The former requires less computational burden and memory than the latter while the latter is suitable for the bias compensated least squares(BCLS) method, which compensates the bias of the LS estimate by the estimates of the input-output noise variances and thus yields unbiased estimates in the presence of high noises.

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A Study on the Construction of a Document Input/Output system (문서 입출력 시스템의 구성에 관한 연구)

  • 함영국;도상윤;정홍규;김우성;박래홍;이창범;김상중
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.29B no.10
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    • pp.100-112
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    • 1992
  • In this paper, an integrated document input/output system is developed which constructs the graphic document from a text file, converts the document into encoded facsimile data, and also recognizes printed/handwritten alphanumerics and Korean characters in a facsimile or graphic document. For an output system, we develop the method which generates bit-map patterns from the document consisting of the KSC5601 and ASCII codes. The binary graphic image, if necessary, is encoded by the G3 coding scheme for facsimile transmission. For a user friendly input system for documents consisting of alphanumerics and Korean characters obtained from a facsimile or scanner, we propose a document recognition algirithm utilizing several special features(partial projection, cross point, and distance features) and the membership function of the fuzzy set theory. In summary, we develop an integrated document input/output system and its performance is demonstrated via computer simulation.

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Adaptive group of ink drop spread: a computer code to unfold neutron noise sources in reactor cores

  • Hosseini, Seyed Abolfazl;Afrakoti, Iman Esmaili Paeen
    • Nuclear Engineering and Technology
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    • v.49 no.7
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    • pp.1369-1378
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    • 2017
  • The present paper reports the development of a computational code based on the Adaptive Group of Ink Drop Spread (AGIDS) for reconstruction of the neutron noise sources in reactor cores. AGIDS algorithm was developed as a fuzzy inference system based on the active learning method. The main idea of the active learning method is to break a multiple input-single output system into a single input-single output system. This leads to the ability to simulate a large system with high accuracy. In the present study, vibrating absorber-type neutron noise source in an International Atomic Energy Agency-two dimensional reactor core is considered in neutron noise calculation. The neutron noise distribution in the detectors was calculated using the Galerkin finite element method. Linear approximation of the shape function in each triangle element was used in the Galerkin finite element method. Both the real and imaginary parts of the calculated neutron distribution of the detectors were considered input data in the developed computational code based on AGIDS. The output of the computational code is the strength, frequency, and position (X and Y coordinates) of the neutron noise sources. The calculated fraction of variance unexplained error for output parameters including strength, frequency, and X and Y coordinates of the considered neutron noise sources were 0.002682/cm3s, 0.002682 Hz, and 0.004254 cm and 0.006140 cm, respectively.