• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.4
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• pp.331-338
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• 1992

The application of Connectionist expert system using neural network to fault diagnosis of power system is presented and compared with rule-based expert system. Also, the merits of Connectionist model using neural network is presented. In this paper, the neural network for fault diagnosis is hierarchically composed by 3 neural network classes. The whole power system is divided into subsystems, the neural networks (Class II) which take charge of each subsystem and the neural network (Class III) which connects subsystems are composed. Every section of power system is classified into one of the typical sections which can be applied with same diagnosis rules, as line-section, bus-section, transformer-section. For each typical section, only one neural network (Class I) is composed. As the proposed model has hierarchical structure, the great reduction of learning structure is achieved. With parallel distributed processing, we show the possibility of on-line fault diagnosis.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.324-327
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• 2002

For the characterization of arbitrary shaped printed circuit board, lossy transmission line grid model based on SPICE netlist and analytical plane model based on the segmentation method are proposed in this paper. Two methods are compared with an arbitrary shaped power/ground plane. Furthermore, design considerations for the complete power distribution network structure are discussed to ensure the maximum value of the PDN impedance is low enough across the desired frequency range and to guide decoupling capacitor selection.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1244-1246
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• 1998

This paper present a variety fault problem brought out with the multifunctional Battery Energy Storage System [MBESS] expected to be practical in the short future interconnected to power distribution system. Multifunctional BESS model and interconnection model to power system is simply configured, the problems of protection coordination and operation is studied. A line fault in the power distribution system are discussed such as line to ground and three phase fault in order to show the impact on power utilities, demand-side and BESS-side. In order to simulate a variable transient phenomenon due to 2 the BESS interconnection operation to power distribution system, in this paper, PSCAD/EMTDC simulation tools is used.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.91-97
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• 1998

The analysis model is the infinite body consisted of power law creep material containing a rigid inclusion with line crack shape subjected to the arbitrarily directional stress on an infinite boundary. The crack analysis is performed using the complex pseudo-stress function. The strain rate intensity factor is determined in the closed form as new fracture mechanics parmeter which represents the magnitudes of stress and strain rate near the tip in power law creep material.

• Journal of Power Electronics
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• v.18 no.1
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• pp.234-250
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• 2018

This paper presents a new load sharing control for use between paralleled three-phase inverters in an islanded microgrid based on the online line impedance estimation by the use of a Kalman filter. In this study, the mismatch of power sharing when the line impedance changes due to temperature, frequency, significant differences in line parameters and the requirements of the Plug-and-Play mode for inverters connected to a microgrid has been solved. In addition, this paper also presents a new droop control method working with the line impedance that is different from the traditional droop algorithm when the line impedance is assumed to be pure resistance or pure inductance. In this paper, the line impedance estimation for parallel inverters uses the minimum square method combined with a Kalman filter. In addition, the secondary control loops are designed to restore the voltage amplitude and frequency of a microgrid by using a combined nominal value SOGI-PLL with a generalized integral block and phase lock loop to monitor the exact voltage magnitude and frequency phase at the PCC. A control model has been simulated in Matlab/Simulink with three voltage source inverters connected in parallel for different ratios of power sharing. The simulation results demonstrate the accuracy of the proposed control method.

• Industrial Engineering and Management Systems
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• v.7 no.2
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• pp.160-170
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• 2008

This paper proposes a mathematical model for converting conveyor assembly line to cellular manufacturing in complex production environments. Complex production environments refer to the situations with multi-products, variant demand, different batch sizes and the worker abilities varying with work stations and products respectively. The model proposed in this paper aims to determine (1) how many cells should be formatted; (2) how many workers should be assigned in each cell; (3) and how many workers should be rested in shortened conveyor line when a conveyor assembly line should be converted, in order to optimize system performances which are defined as the total throughput time and total labor power. We refer the model to a new production system. Such model can be used as an evaluation tool in the cases of (i) when a company wants to change its production system (usually a belt conveyor line) to a new one (including cell manufacturing); (ii) when a company wants to evaluate the performance of its converted system. Simulation experiments based on the data collected from the previous documents are used to estimate the marginal impact that each factor change has had on the estimated performance improvement resulting from the conversion.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.41-45
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• 2019

In this paper, we propose the interference cancellation scheme of end-to-end method algorithm for power line communication (PLC) systems in smart grid. The proposed scheme estimates the channel noise information of receiver by applying a deep learning model at the receiver. Then, the estimated channel noise is updated in database. In the modulator, the channel noise which reduces the power line communication performance is effectively removed through interference cancellation technique. As an impulsive noise model, Middleton Class A interference model was employed. The performance is evaluated in terms of bit error rate (BER). From the simulation results, it is confirmed that the proposed scheme has better BER performance compared to the theoretical model based on additive white Gaussian noise. As a result, the proposed interference cancellation with deep learning improves the signal quality of PLC systems by effectively removing the channel noise. The results of the paper can be applied to PLC for smart grid and general communication systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.4
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• pp.29-33
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• 2022

In this paper, we propose the deep learning based pre interference cancellation scheme algorithm for power line communication (PLC) systems in smart grid. The proposed scheme estimates the channel noise information by applying a deep learning model at the transmitter. Then, the estimated channel noise is updated in database. In the modulator, the channel noise which reduces the power line communication performance is effectively removed through interference cancellation technique. As an impulsive noise model, Middleton Class A interference model was employed. The performance is evaluated in terms of bit error rate (BER). From the simulation results, it is confirmed that the proposed scheme has better BER performance compared to the theoretical model based on additive white Gaussian noise. As a result, the proposed interference cancellation with deep learning improves the signal quality of PLC systems by effectively removing the channel noise. The results of the paper can be applied to PLC for smart grid and general communication systems.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.2
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• pp.45-53
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• 2013

In this paper, we analyze the typical phase voltage and line current waveform characteristics of the distribution system with 3 phase small synchronous generation source in case with load and non-load group, in order to investigate the power quality for end load connected of generation source. As demonstrated by our experimental results, the distortion and power quality of phase voltage and line current waveform were relatively good for low voltage 3 phase model grids connected of 3 phase small synchronous generation source in case with non-load group. However, distortion and power quality of voltage and current waveform was poor for low voltage 3 phase model grids connected to 3 phase small synchronous generation source in the load group with some phase voltage and frequency difference. From the above results, we conclude that the phase voltage and frequency of 3 phase generation source must be identical to that of distribution system source to maximize the power quality. Also, special attention is required in case of having load group or non-load group to 3 phase generation source.

• Proceedings of the KIEE Conference
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• summer
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• pp.7-10
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• 2004

This paper illustrates some case studies of reliability evaluation of iEEE MRTS using the tie line constrained equivalent assisting generator model(TEAG) for reliability evaluation of NEAREST. The proposed TEAG is able to supply the information for reliability evaluation of interconnected power systems. It is important that interconnection between power systems can provide the improved levels of reliability. Therefore, It is expected that the TEAG model developed in this study will provide some solution to many problems for interconnected power systems. The characteristics and validity of this developed TEAG considering transmission systems are introduced by case study of IEEE MRTS.