• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.957-959
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• 2014

The wave analysis of cylinders combined rigidly with a finite plate to identify the effect of the plate on the wave propagation. This paper uses the mobility and impedance coupling method to combine a infinite-length cylinder with the plate, and obtains the coupling forces induced by the vibration of the structure. The waveguide finite element method is used to calculate the wave characteristics of the cylinder excited by the forces. From the results, the dispersion diagram can be obtained. It contains the characteristics induced by the vibration and length of the internal plate. It also shows the wave propagation of elastic waves sustained in the cylinder.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1182-1184
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• 1998

Recently high impedance fault(HIF), which includes arcing wave, has often occured in power system. Some papers related to arcing phenomena and its modeling have been published. However the proposed methods show much different form in compare with actual arc wave under HIF. It is not so available to use to analyze HIF because of such problem. This paper proposes the new arcing wave model, which is nearly similar to actual arcing wave, developed using PSCAD/EMTDC. The arcing waves obtained from arcing model that applied in actual. power system are compared with some actual arcing wave gained from the field test and show the availability to application of relay test.

• Journal of applied mathematics & informatics
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• 제41권4호
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• pp.811-819
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• 2023

In this research we have used the definition of standard fractional vector cross product to obtain fractional curl and fractional field of a standing wave, a travelling wave, a transverse wave, a vector field in xy plane, a complex vector field and an electric field. Fractional curl and fractional field for a complex order are also discussed. We have supported the study with calculation of impedance at γ = 0, 0 < γ < 1, γ = 1. The formula discussed in this paper are useful for study of polarization, reflection, impedance, boundary conditions where fractional solutions have applications.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1382-1385
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• 2007

In this paper, we study about the measuring algorithm that can implement Structural Health Monitoring (SHM) more efficiently by two measurement methods using smart sensor. Through the impedance measurement method, the damage condition of structures on wide area is monitored first, and then it changes the mode to guided wave measurement mode by mode switching algorithm when impedance measurement mode detects abnormal signals. Efficient handling of the real-time data would be available by analyzing location and shape of damage through guided wave measurement.

• 대한조선학회논문집
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• 제44권5호
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• pp.488-495
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• 2007

In this paper, SBN (Structure-Borne Noise) reduction of resiliently mounted machinery and effect of the foundation impedance on mount performance is studied. SBN reduction through the mount is analyzed by using two theoretical models; mass-spring model and wave model, in which longitudinal wave propagation is included. It is found that floor impedance greatly affects SBN reduction through lower mount, while it is almost negligible to SBN reduction through upper mount. Comparisons between measurement and predictions shows that the mass-spring model is valid only in low frequency range below few hundred Hz, while for high frequency ranges longitudinal wave propagation in the mount must be considered.

• 한국통신학회논문지
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• 제21권3호
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• pp.771-783
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• 1996

8단자 가변임피던스 전자파 발생장치(8P-VWIG:8Ports-Variable Wave Impedance Generator)에 대한 설계 기술에 대해 나타내고, 내부에서 유기뇌는 전자기장 및 특성임피던스에 대한 수치해석, 일정한 특성임피던스를 갖는 구조에 대해 간단하게 추적할 수 있는 수치알고리즘에 대해 나타내었다. 또한 특정 구조에 대한 균일도 평가결과와 내부 전자계 분포, 그리고 그 응용으로서 EMS 측정시스템에 대한 간단한 소개를 나타내었다. 8P-VWIG는 기존 간이 EMI/EMS 시설들에 비해 시험공간의 활용도가 좋고, 수직 수평 분극 조성이 자유로운 장점을 가지고 있다. 제작된 8P-VWIG는 정재파비로 측정된 제 1공진이 152.1MHz에서 발생하고, $50{\Omega}$ 임피던스 정합 시스템으로 동작하도록 한 8채널의 다중전송선로 구조를 갖는다.

• Geomechanics and Engineering
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• 제12권1호
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• pp.161-183
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• 2017

This paper investigates the damage identification of the concrete pile element through axial wave propagation technique using computational and experimental studies. Now-a-days, concrete pile foundations are often common in all engineering structures and their safety is significant for preventing the failure. Damage detection and estimation in a sub-structure is challenging as the visual picture of the sub-structure and its condition is not well known and the state of the structure or foundation can be inferred only through its static and dynamic response. The concept of wave propagation involves dynamic impedance and whenever a wave encounters a changing impedance (due to loss of stiffness), a reflecting wave is generated with the total strain energy forked as reflected as well as refracted portions. Among many frequency domain methods, the Spectral Finite Element method (SFEM) has been found suitable for analysis of wave propagation in real engineering structures as the formulation is based on dynamic equilibrium under harmonic steady state excitation. The feasibility of the axial wave propagation technique is studied through numerical simulations using Elementary rod theory and higher order Love rod theory under SFEM and ABAQUS dynamic explicit analysis with experimental validation exercise. Towards simulating the damage scenario in a pile element, dis-continuity (impedance mismatch) is induced by varying its cross-sectional area along its length. Both experimental and computational investigations are performed under pulse-echo and pitch-catch configuration methods. Analytical and experimental results are in good agreement.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1407-1412
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• 2004

Impedance calculations of electric railway traction systems is essential to define characteristics and to design it. The self impedance is defined voltage drop rate per unit length, the mutual impedance is represented as a voltage induced to transmission line from transmission line. The self and the mutual impedance are influenced by ground return currents. The earth is considered as a semi-infinitely extended non-ideal conductor. The current of transmission line produces earth current induced magnetically and it flow through a path having minimum impedance. Carson proposed the impedance calculation formula using wave equations and magnetic field equations. Though the formula have an improper equation, that is still used as a standard impedance calculation method. This paper introduced an impedance calculation method that the complex depth of earth return method assumes that the current in conductor returns through an imagined earth depth path located directly under original conductor at a depth of. In this paper, we showed that this proposed method has a closed form and is easier than Carson's.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2002년도 학술대회논문집
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• pp.303-306
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• 2002

This paper presents a novel method for measuring the ground impedance in grounding systems. A square wave current was injected to the main grounding grid through auxiliary electrode, and the test current and ground potential rise(GPR) were measured using the band-pass filter. Ground impedance was calculated from the sinusoidal waveforms of the test current and GPR in frequency range of 20~2100Hz. Also the resistance and reactance component of ground impedance were analyzed.

• 전자공학회논문지A
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• 제29A권2호
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• pp.24-32
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• 1992

The impedance matching properties of infinite planar arrays of rectangular waveguides with dielectric plug loading and sheath covering are studied here. The effects of several involved parameters on the impedance matching of the phased array antenna are investigated by calculating the reflection coefficients numerically. The improvement of impedance matching and the appearance of forced surface wave resonances are also discussed.