• The Journal of the Acoustical Society of Korea
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• v.28 no.2E
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• pp.51-59
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• 2009

Mutual radiation impedance becomes more important in the design and analysis of acoustic transducers for higher power, better beam pattern, and wider bandwidth at low frequency sonar systems. This review paper focused on literature survey about the researches of mutual radiation impedance in the acoustic transducer arrays over 60 years. The papers of mutual radiation impedance were summarized in terms of transducer array structures on various baffle geometries such as planar, cylindrical, spherical, conformal, spheroidal, and elliptic cylindrical arrays. Then the computation schemes of solving conventional quadruple integral in the definition of mutual radiation impedance were surveyed including spatial convolution method, which reduces the quadruple integral to a double integral for efficient computation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1223-1228
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• 2008

While a high frequency source is used for measuring the ground impedance, there are several factors having an effect on the measured value. A primary factor of the measurement error is the ac mutual coupling between current and potential test leads. The mutual coupling causes the test current to induce a voltage into the potential test lead that adds to the actual ground potential rise and produces a significant measurement error as the length of the test leads paralleled is prolonged. In order to avoid the mutual coupling, it is recommended that the ground impedance be measured by angled arrangement of test leads. The mutual impedance due to the inductive coupling with an angle of $90^{\circ}$ was calculated at $0^{\circ}$ by Campbell/Foster Method. With an angle of $180^{\circ}$, the mutual impedance was calculated large value enough to introduce a fairly large margin of error, however, the measured value of ground impedance was close to the value at $90^{\circ}$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1778-1783
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• 2009

Ground impedance for the large grounding system is measured according to the IEEE Standard 81.2 which is based on the revised fall-of-potential method of installing auxiliary electrode at a right angle. When the auxiliary electrodes are located at an angle of $90^{\circ}$, the ground impedance inevitably includes the error due to earth mutual resistance. In this paper, in order to accurately measure the ground impedance of vertically-driven ground electrodes, error rates due to earth mutual resistance are evaluated by ground resistance and ground impedance measuring devices and compared with calculated values. As a result, the measured results are in good agreement with the computed results considering soil layer with different resistivity. The error rates due to earth mutual resistance decrease with increasing the length of ground electrode in the case that the ratio of the distance between the ground rod to be measured and the auxiliary electrodes to the length of ground electrode(D/L) is same. The ground impedance should be measured at the minimum distance between the auxiliary electrodes that will have an estimated measurement accuracy due to earth mutual resistance.

• Journal of electromagnetic engineering and science
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• v.13 no.4
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• pp.240-244
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• 2013

In this paper, we present an improvement of a closed-form formula for mutual impedance computation. Depending on the center-to-center spacing between two rectangular microstrip patch antennas, the mutual impedance formula is separated into two parts. The formula based on synthetic asymptote and variable separation is utilized for spacings of more than 0.5 ${\lambda}_0$. When the spacing is less than 0.5 ${\lambda}_0$, an approximate formula is proposed to improve the computation for closely spaced elements. Simulation results are compared to computational results of mutual impedances and mutual coupling coefficients as functions of normalized center-to-center spacing in both E- and H-plane coupling configurations. A good agreement between simulation and computation is achieved.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1470-1471
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• 2007

The mutual coupling between the current and potential measuring wires makes serious effect on the measurement of the ground impedance. For analyzing the effect of mutual coupling, we compared the ground impedance measured on site with the ground impedance calculated with MATLAB. When the parallel length is 10 [m], the measured ground impedance is similar with the calculated ground impedance. As the parallel length is extended over 10 [m], the error between measured ground impedance and calculated ground impedance is also increased on a large scale. We analyzed the mutual coupling by the frequency and present the inaccuracy of ground impedance quantitatively.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.4
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• pp.221-226
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• 2004

Power system has recently used Double-circuit Line and Multi-circuit Line in the industrial development. This has an advantage of system stability and reliability, but the complexity of the system has a disadvantage that makes it difficult to protect the power line. Double-circuit Line has two operation conditions in the Single-circuit operation and Double-circuit operation, so it has mutual impedance. To make it possible for the remaining single-line to operate independently while there is a fault with first line or when maintenance is needed, a trip region for the single-circuit operation should be set in order to set the relay trip region. An optimal trip region for each operation, a different operational conditions for the relay setting should be calculated. In this paper, trip regions of each operation condition have been compared by considering mutual impedance and fault resistance that led to the calculation of fault impedance. Also, as we know that one of the advantages in the distance relay is the back-up protection, we calculated the trip region(Zone-2) in consideration of the mutual impedance.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.4
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• pp.221-221
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• 2004

Power system has recently used Double-circuit Line and Multi-circuit Line in the industrial development. This has an advantage of system stability and reliability, but the complexity of the system has a disadvantage that makes it difficult to protect the power line. Double-circuit Line has two operation conditions in the Single-circuit operation and Double-circuit operation, so it has mutual impedance. To make it possible for the remaining single-line to operate independently while there is a fault with first line or when maintenance is needed, a trip region for the single-circuit operation should be set in order to set the relay trip region. An optimal trip region for each operation, a different operational conditions for the relay setting should be calculated. In this paper, trip regions of each operation condition have been compared by considering mutual impedance and fault resistance that led to the calculation of fault impedance. Also, as we know that one of the advantages in the distance relay is the back-up protection, we calculated the trip region(Zone-2) in consideration of the mutual impedance.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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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.

• Journal of electromagnetic engineering and science
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• v.11 no.3
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• pp.152-155
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• 2011

This paper describes the role of mutual impedance and the transducer power gain which comes from key parameters to determine the amount of wireless power especially in a near-field environment. These two key parameters are applied to the two configurations; one is a dipole-dipole, and the other is a dipole-metal plate-loop configuration. Discussions are given on the achievable maximum power transfer between the sender and the receiver affected by the matching and the pass blockage.

• The Journal of the Acoustical Society of Korea
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• v.14 no.6
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• pp.21-26
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• 1995

In this paper integral equations are derived and simulated numerically for the mutual radiation impedance of an acoustic transducer in a Plane array. It is assumed that the pistons are mounted in the rigid infinite baffle. The mutual radiation impedance is separated into resistance and reactance and plotted as a function of ka and kd. Mutual radiation resistance is decreased and perturbed according to increase of ka. Mutual radiation reactance is decreased along to increase of ka. Mutual impedance is decreased when kd is increased. However, when ka is 6, 13, and 19 the interaction effect is decayed. When the relative piston position of the two pistons is 45 degree, the amount of interaction becomes minimized.