• KIEE International Transactions on Power Engineering
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• v.11A no.4
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• pp.15-20
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• 2001

Power system stability is correlated with system structure, disturbances and operating conditions, and power flows on transmission lines are closely related with those conditions. This paper proposes a methodology to identify correlative power flows for power system transient and small-signal stability prediction. In transient stability sense, the Critical Clearing Time is used to select some dominant contingencies, and Transient Stability Prediction index is proposed for the quantitative comparison. For small-signal stability discusses a methodology to identify crucial transmission lines for stability prediction by introducing a sensitivity factor based on eigenvalue sensitivity technique. On-line monitoring of the selected lines enables to predict system stability in real-time. Also, a procedure to make a priority list of monitored transmission lines is proposed. The procedure is applied to a test system, and it shows capabilities of the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.5
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• pp.271-278
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• 2003

Power system stability is correlated with system structure, disturbances and operating conditions, and power flows on transmission lines are closely related with those conditions. This paper proposes a methodology to identify correlative power flows for power system transient and small-signal stability prediction. In transient stability sense, the Critical Clearing Time is used to select some dominant contingencies, and Transient Stability Prediction index is proposed for the quantitative comparison. For small-signal stability, this paper discusses a methodology to identify crucial transmission lines for stability Prediction by introducing a sensitivity factor based on eigenvalue sensitivity technique. On-line monitoring of the selected lines enables to predict system stability in real-time. Also, a Procedure to make a priority list of monitored transmission lines is proposed. The procedure is applied to a test system and the KEPCO systems in the year of 2003 and it shows capabilities of the proposed method

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.4
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• pp.260-266
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• 2007

Analytical compact form models for the signal transients and crosstalk noise of inductive-effect-prominent multi-coupled RLC lines are developed. Capacitive and inductive coupling effects are investigated and formulated in terms of the equivalent transmission line model and transmission line parameters for fundamental modes. The signal transients and crosstalk noise expressions of two coupled lines are derived by using a waveform approximation technique. It is shown that the models have excellent agreement with SPICE simulation.

• Fashion & Textile Research Journal
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• v.23 no.4
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• pp.527-535
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• 2021

In this study, electroconductive textiles were developed by screen-printing technology using a complex solution of PEDOT:PSS/AgNW on a polylactic acid nanofiber web. A performance evaluation was then conducted to utilize this electroconductive textile as a signal transmission line. To obtain highly conductive electroconductive textiles, this study sought to determine the optimal mixing ratio of PEDOT:PSS/AgNW. Sheet resistance was measured to evaluate the electrical properties of electroconductive textiles, Finite element-scanning electron microscopy images were then used to examine surface properties, and Fourier transform-infrared analysis was performed to evaluate chemical properties. The signal waveform characteristics of the electroconductive textile were observed using a signal generator and an oscilloscope. Radio-frequency characteristics were then evaluated to confirm frequency range, and bending tests were conducted to evaluate durability. The signal transmission lines produced in this study had a sheet resistance value of 3.30 ?/sq, and signal transmission performance was evaluated to observe that the input value of the voltage was nearly identical to the output value. In addition, S21 analysis confirmed that it was available in the frequency domain up to 35 MHz. The performances of the transmission lines were maintained after 100, 200, 500, and 1,000 repeated bending tests, and sufficient durability was confirmed.

• Journal of the Korean Society of Clothing and Textiles
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• v.46 no.2
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• pp.367-374
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• 2022

Herein, a highly elastic e-textile band with a two-wire transmission line was designed and fabricated for smart clothing applications. A conductive yarn with a very uniform low electrical resistance of 0.0357 Ω/cm was developed and used for the signal and ground lines. To control the elasticity of the e-textile band, spandex yarns were added in the warp direction during knitting and the tension was adjusted. As the length of the e-textile band increased, its RF performance deteriorated. Furthermore, the frequency corresponding to -3 dB S21 was lower in the 30% stretched band than in the unstretched band. For the e-textile bands with lengths 10, 50, and 100 cm, the frequencies corresponding to -3 dB S21 were 107.77, 24.56, and 13.02 MHz when not stretched, and 88.74, 22.02, and 12.60 MHz when stretched by 30%. The fabricated bands were flatter, more flexible, and more elastic than transmission line cables; thus, they can be easily integrated into wearables and smart clothing. However, to increase RF performance and achieve optimum utilization, future studies must focus on the fabrication of transmission lines with lower resistance and reduced distance between the signal and ground lines, and thus the number of transmission lines can be increased.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.809-811
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• 1993

The load impedance of power lines generally varies with time, areas, and season. Also, the harmonic noises by the power electrical equipments are scattered through the power lines. The received signal level varies with the environment and is not able to detect the PLC(Power Line Carrier) signal. For this reason, it is requried for the signal transmitter to hold the received signal level uniform independently with the variation of the load impedence. In this paper, the power lines are modeled simply and a method keeping the received signal level uniform is suggested through the analysis of the signal transmission characteritics of the PLC coupler using tank circuit.

• Journal of Electrical Engineering and Technology
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• v.6 no.6
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• pp.742-749
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• 2011

Power transmission lines are one of the most important components of electric power system. Failures in the operation of power transmission lines can result in serious power system problems. Hence, fault diagnosis (transient or permanent) in power transmission lines is very important to ensure the reliable operation of the power system. A hidden Markov model (HMM), a powerful pattern recognizer, classifies events in a probabilistic manner based on fault signal waveform and characteristics. This paper presents application of HMM to classify faults in overhead power transmission lines. The algorithm uses voltage samples of one-fourth cycle from the inception of the fault. The simulation performed in EMTPWorks and MATLAB environments validates the fast response of the classifier, which provides fast and accurate protection scheme for power transmission lines.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.6
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• pp.282-287
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• 2004

Since the manufacturing process in the LTCC process does not allow solid ground planes between ceramic layers to isolate the signal lines, the buried ground should be realized as a meshed ground plane. Both characteristic impedances of the signal lines and couplings between different signal layers are influenced by the properties of these meshed planes. In this paper, we propose a new analysis method for coupling behavior between internal transmission lines, which are isolated by the buried meshed-ground planes. The coupling behavior between layers isolated by meshed-ground planes is investigated by the coupled-transmission line model for the isolated layers. The coupling factors between isolated lines with the meshed-ground are extracted by 2-D FEM calculations.

• Journal of Drive and Control
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• v.18 no.2
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• pp.9-19
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• 2021

The spool displacement signal of a directional control valve, including the servo valve, can be considered as the standard signal to measure dynamic characteristics. When the spool displacement signal is not available, the velocity signal of a metering cylinder piston can be used. In this study, the frequency response characteristics of the metering cylinder are investigated for the spool displacement input. The transfer functions of the servo valve-metering system are derived taking into consideration the oil inertia effect in the transmission lines. The theoretical results of the transfer functions are verified through computer simulations and experiments. The oil inertia effect in the transmission lines was found to have a very significant effect on the bandwidth frequency of the servo valve-metering cylinder system. In order to more precisely measure the dynamic characteristics of a servo valve, the metering cylinder should be set up to minimize the oil inertia effect by increasing the inner diameters of the transmission lines or shortening their lengths.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.8
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• pp.16-25
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• 1994

The prediction of crosstalk in one of important problems in estimating the EMC of a system for high speed digital signal transmission. Crosstalk curves are shown in terms of characteristic impedance of lines spacing between lines and rise time of pulse by using general multiple coupled transmission line equation and harmonic-balance method. The coupled symmetrical two-line on dielectric material epoxy-glass FR 4(${\varepsilon}_r$), is fabricated to measure crosstalk occuring at the near end and far end of the passive line. The inter-line is inserted to reduce crosstalk between two microstrip lines. The simulation results and the measurement results are shown and found to be very close.