• 한국광학회:학술대회논문집
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• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.165-168
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• 1989

A finite-element method is developed to calculate the impedance of arbitrarily shaped electrodes on traveling-wave modulators. This method employs the divergence theorem to obtain the total charge on an electrode from the node potential values. By using this method, the impedance of multi strip-line electrodes on anisotropic inhomogeneous dielectric media was analysed and the effect of non-zero electrode thickness was calculated.

• ETRI Journal
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• 제32권6호
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• pp.969-971
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• 2010

Based on a de-embedding technique, a new method is proposed which is capable of evaluating chip impedance behavior over absorbed power in flip-chip bonded UHF radio frequency identification transponder ICs. For the de-embedding, four compact co-planar test fixtures, an equivalent circuit for the fixtures, and a parameter extraction procedure for the circuit are developed. The fixtures are designed such that the chip can absorb as much power as possible from a power source without radiating appreciable power. Experimental results show that the proposed modeling method is accurate and produces reliable chip impedance values related with absorbed power.

• 대한의용생체공학회:의공학회지
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• 제13권1호
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• pp.47-54
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• 1992

We studied the characteristics of the compound electrode and found that the compound electrode provides the four-electrode method in a compact form. We developed a new method of measuring the skin impedance using simple electrodes at low frequencies. At high frequencies where the effect of internal tissue impedance is not negligible, we used the compensation method using compound electrodes since they measure the voltage right under the skin. At 50 kHz, we measured the real part of the skin impedance of less than $80{\Omega}$ on the thorax. We propose a simple instrument which can measure accurate skin impedance at various frequencies.

• International Journal of Concrete Structures and Materials
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• 제2권2호
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• pp.99-105
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• 2008

Southern exposure test specimens were used to evaluate corrosion performance of epoxy-coated reinforcing bars in chloride contaminated concrete by electrochemical impedance spectroscopy method. The test specimens with conventional bars, epoxy-coated bars and corrosion inhibitors were subjected 48 weekly cycles of ponding with sodium chloride solution and drying. The polarization resistance obtained from the Nyquist plot was the key parameter to characterize the degree of reinforcement corrosion. The impedance spectra of specimens with epoxy-coated bars are mainly governed by the arc of the interfacial film and the resistance against the charge transfer through the coating is an order of magnitude higher than that of the reference steel bars. Test results show good performance of epoxy-coated bars, although the coatings had holes simulating partial damage, and the effectiveness of corrosion-inhibiting additives. The corrosion rate obtained from the impedance spectroscopy method is equivalent to those determined by the linear polarization method for estimating the rate of corrosion of reinforcing steel in concrete structures.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.313-316
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• 2008

This paper presents the error factors of Fall-of-potential test method used in measurements of the grounding-system impedance. This test methods inherently can introduce two possible errors in the measurements of grounding-system impedance: (1) ground mutual resistance due to current flow through ground from the ground electrode to the current probe, (2) ac mutual coupling between the current test lead and the potential test lead. The errors of ground mutual resistances and ac mutual coupling are expressed by the equation in calculating grounding impedance. These equations were calculated by Matlab that is commercial tool using mathematical calculation. The results of calculation were applied to correct grounding impedance.

• 대한의용생체공학회:의공학회지
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• 제15권4호
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• pp.413-418
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• 1994

In electrical impedance tomography (EIT), we use boundary current and voltage measurements to provide the information about the cross-sectional distribution of electrical impedance or resistivity One of the major problems in EIT has been the inaccessibility of internal voltage or current data in finding the internal impedance values. We propose a new image reconstruction method using internal current density data measured by NMR. We obtained a two-dimensional current density distribution within a phantom by processing the real and imaginary MR images from a 4.7T NMR machine. We implemented a resistivity image reconstruction algorithm using the finite element method and sensitivity matrix. We presented computer simulation results of the image reconstruction algorithm and furture direction of the research.

• 한국조명전기설비학회지:조명전기설비
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• 제13권2호
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• pp.212-212
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• 1999

This paper proposed a high impedance fault detection method using a neural network on distribution lines. The v-I characteristic curve was obtained by high impedance fault data tested in various soil conditions. High impedance fault was simulated using EMTP. The pattern of High Impedance Fault on high density pebbles was taken as the learning model, and the neural network was valuated on various soil conditions. The average values after analyzing fault current by FFT of evenr·odd harmonics and fundamental rms were used for the neural network input. Test results were verified the validity of the proposed method.

• 설비공학논문집
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• 제15권5호
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• pp.413-421
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• 2003

The acoustic performances of steel-wire sound absorbing materials with different thicknesses and bulk densities were investigated experimentally. The well-known two-cavity method was used to measure the characteristic impedance, propagation constant and absorption coefficient. The normal absorption coefficients measured by two-cavity method agreed well with those by the two-microphone impedance tube method. The experimental results showed that the magnitude of the absorption coefficient and the frequency range of the maximum absorption coefficient were controllable by changing the thickness and bulk density of the steel-wire. Therefore, the steel-wires obtained from the crushed tire chips could be used as a good absorbing material.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.352-355
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• 2009

The ground resistance has been used as a method of estimating the capability of counterpoise. When transient currents blow through a ground electrode, it is reasonable to evaluate the performance of ground electrode system as a ground impedance instead of ground resistance. However, the measurement method of ground impedance for counterpoise is not clearly presented. This paper describes the measurement method of ground impedance considering the earth mutual resistances and AC mutual coupling. When we measure the ground impedance, the error due to earth mutual resistances depends on the distance between the auxiliary electrodes and the electrode under test. The measurement accuracy of high frequency ground impedance is mainly influenced by the location of the current electrode and the potential electrode.

• 조명전기설비학회논문지
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• 제18권4호
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• pp.181-187
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• 2004

3상 4선식 배전계통을 채용하는 우리나라는 비선형 부하의 증가로 중성선에는 많은 중성선 고조파 전류가 관측되고 있다. 또한 접지 임피던스는 고조파가 있는 중성선 전류에 영향 끼친다고 알려져 있다. 전위 강하법에 따라 현장에서 실측한 고조파 전류와 전압을 측정하고, Pattern Search 기법으로 고조파 해석용 접지 임피던스를 모델링 하였다. 여기서 구한 임피던스 모델은 현장 시험에 의한 임피던스 모델과 비교하여 유사한 결과를 얻었고, 접지 시스템의 고조파 및 과도 응답 특성을 평가하는데 활용될 것으로 사료된다.