• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.399-402
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• 2002

In this paper, the novel method is proposed to measure the capacitance of the dc link capacitor Advantage of the method is not to separate capacitor from 3-phase AC/DC/AC converters. In the proposed method, a specific low frequency current is injected to oscillate the voltage of dc capacitor at no load condition. The capacitance of dc capacitor is calculated with the effective values of this ripple voltage and current. The validity of the proposed method is confirmed by PSIM simulation.

• Journal of Power Electronics
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• v.13 no.1
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• pp.94-103
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• 2013

A capacitor deterioration of LCL-filter grid-connected PWM converters is progressed by the self-healing mechanism. It leads to the degradation of the filter performance and drop of power factor. Thus, it is required to diagnose fault-point of capacitors and determine the replacement time. Typically, the fault of capacitors is determined when the capacitance is reduced up to 80% from initial value. This paper proposes algorithm to the determine capacitor replacement time of an LCL filter. The algorithm takes the advantage of change of the response on the injected resonant frequency corresponding to 80% value from the initial capacitance. The results of the algorithm are demonstrated through simulations and experiments.

• Corrosion Science and Technology
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• v.20 no.5
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• pp.231-241
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• 2021

The objective of this study was to evaluate total current under steady-state conditions for a material undergoing corrosion using the electrochemical frequency modulation (EFM) technique, taking into account the presence of solution resistance and double layer capacitance. The analysis involving linearization of the Tafel curve allowed for the estimation of corrosion parameters. Results showed that the output signal was dependent on fundamental frequencies and their multiples. In addition, the output signal almost manifested itself at frequencies that were sums of fundamental frequencies of the applied sinusoidal signal. The harmonics calculated showed a significant shift from the principal frequency of input signals. The investigation involved the influence of corrosion current and anode-to-cathode Tafel slope ratio on faradaic and non-faradaic currents (including the average and RMS). The model presented showed both qualitative and quantitative improvements over the previously developed EFM technique that ignored the influence of solution resistance and the double layer capacitance while assuming the applied DC potential corresponded to the corrosion potential of the corroding material.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.1
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• pp.80-86
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• 2002

This paper describes to extend the MLFMA(Multi-Level Fast Multipole Algorithm) for three-dimensional capacitance computation in the case of conductors embedded in an arbitrary dielectric medium. The triangular meshes are used and refined in the area which has heavy charge density. This technique is applied to the capacitance extraction of three-dimensional structures with multiple dielectrics. The results show good convergence with the comparable accuracy, and this adaptive technique coupled with MLFMA is useful to reduce computing time and the number of elements with least additional computational efforts in large three dimensional problems.

• Progress in Medical Physics
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• v.3 no.2
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• pp.43-57
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• 1992

Phase detector techique provides a unique probe to membrane recycling phenomenon by enabling dynamic monitoring of cell membrane capacitance. However, it has inherent errors due to constant changes in measurement environments. The present study analyzed several error sources to develope application criteria of this technique. and the following was found based on a theoretical analysis. The initial phase angle has to be appropriately selected to minimize the error due to perturbation of access and membrane conductances. Excitation frequency is also important to determine the initial phase angle. However. deviation of the phase angle from a predetermined initial value during the measurement period does not affect capacitance estimation to a significant degree. Despite an appropriate initial phase selection an error in scaling factor is expected for a large increase in capacitance during exocytosis. which may be overcome by iteratively correcting the scaling factor over the measurement period. These results will provide a useful guideline in practical application of this technique.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.542-543
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• 2014

In this paper, an estimation scheme based on an augmented sigma-point Kalman filter to estimate the state of charge (SOC) of the battery is presented, where the battery parameters of the series resistance ($R_o$), diffusion capacitance ($C_1$) and resistance ($R_1$) are also estimated through the recursive least squares (RLS) for better accuracy of the SOC. The effectiveness of the proposed method is verified by simulation results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1294-1303
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• 2009

This paper presents a new numerical algorithm for fault discrimination and fault location estimation when occur to arcing ground and arcing line to line on transmission lines. The object of this paper is developed from new numerical algorithm to calculate the fault distance and simultaneously to make a distinction between transient and permanent faults. so the first of object for propose algorithm would be distinguish the permanent from the transient faults. This arcing fault discrimination algorithm is used if calculated value of arc voltage amplitude is greater than product of arc voltage gradient and the length of the arc path, which is equal or greater than the flashover length of a suspension insulator string[1-3]. Also, each algorithm is separated from short distance and long distance. This is difference to with/without capacitance between short to long distance. To test the validity of the proposed algorithms, the results of algorithm testing through various computer simulations are given. The test was simulated in EMTP/ATP simulator under a number of scenarios and calculate of algorithm was used to MATLAB.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.11
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• pp.96-104
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• 2000

This paper presents a simple method to estimate short-circuit power dissipation for static CMOS logic circuits. Short-circuit current expression is derived by accurately interpolating peak points of actual current curves which is influenced by the gate-to-drain coupling capacitance. It is shown through simulations that the proposed technique yields better accuracy than previous methods when signal transition time and/or load capacitance decreases, which is a characteristic of the present technological evolution. The proposed analytical expressions can be easily applied in such applications as power estimation even when the current expression is changed.

• Structural Monitoring and Maintenance
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• v.4 no.1
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• pp.69-84
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• 2017

Delamination is the most common failure mode in layered composite materials. The author have found that the electrical potential change (EPC) technique using response surfaces method is very effective in assessment delamination in basalt fiber reinforced polymer (FRP) laminate composite pipe by using electrical capacitance sensor (ECS). In the present study, the effect of the electrodes number on the method is investigated using FEM analyses for delamination location/size detection by ANSYS and MATLAB, which are combined to simulate sensor characteristic. Three cases of electrodes number are analyzed here are eight, twelve and sixteen electrodes, afterwards, the delamination is introduced into between the three layers [$0^{\circ}/90^{\circ}/0^{\circ}$]s laminates pipe, split into eight, twelve and sixteen scenarios for cases of eight, twelve and sixteen electrodes respectively. Response surfaces are adopted as a tool for solving inverse problems to estimate delamination location/size from the measured EPC of all segments between electrodes. As a result, it was revealed that the estimation performances of delamination location/size depends on the electrodes number. For ECS, the high number of electrodes is required to obtain high estimation performances of delamination location/size. The illustrated results are in excellent agreement with solutions available in the literature, thus validating the accuracy and reliability of the proposed technique.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.10a
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• pp.515-520
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• 2004

In this paper, a passive telemetry RF capacitive humidity sensor system using a RLSE(Recursive Least Square Estimation) technique is proposed. To overcome these trouble problems such as a power limitation and a estimation complexity that the general passive telemetry sensor system including It chip has, the principle of inductive coupling was applied to the modeling of a passive telemetry RF capacitive humidity sensor system and its capacitance was estimatedd by the RLSE algorithm. Specially, by introducing the optimal forgetting factor, we showed that the accuracy of its estimation was improved even in the time varying system and also the convergence time was reduced.