• Journal of the Korean Institute of Telematics and Electronics
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• v.6 no.1
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• pp.12-18
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• 1969

The characteristics of microwave reflection in the media of cold gaseous plasma is analysed to various external magnetic flux density. The DC discharge plasma is generated in the rectangular waveguide which contains two electrodes and helium gas at the pressure of 10-2mm Hg. The reflected and transmitted power of microwave is measured when the electric field is parallel to, and perpendicular to the external magnetic field. It shows that the reflected power is increased as the magnetic flux density is increased in the parallel case, but the maximum value of the reflected power is occured at the cyclotron resonance (3120 Gauss) in the perpendicular case.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1269-1274
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• 2014

Since power and control cables have narrow bandwidth due to their loss at high frequencies, it is difficult to detect the weak fault using conventional reflectometry. It is because the reflected wave caused by the weak fault is overlapped and hidden by the ripple of the strong reflected wave from the end of the cable. This paper proves that the reflected wave from the weak fault can be considered to be linearly superposed on the strong reflected wave from the end of the cable based on the transmission line theory. Then, the weak fault point is experimentally diagnosed using the difference between reflection coefficients before and after the fault generation.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1870-1871
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• 2011

본 논문에서는 전력케이블에서의 시간-주파수 영역 반사파 계측법을 기반으로 한 기준신호를 설계한다. 사용된 기준신호는 시간과 주파수 영역에서 동시에 분석할 수 있는 가우시안 포락선을 가지는 첩 신호이다. 10m 전력케이블의 특성에 적합하게 설계된 기준신호를 케이블에 직접 인가하여 반사파를 측정하고 정규화된 시간-주파수 영역 상호상관함수로 비교 분석하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.153-157
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• 2008

Recently, electronic devices is produced by multilayer structure, therefore analysis for hidden layers is important nondestructive inspection. This paper presents visibility enhancement methods for the ultrasonic multiple echoes reflected from adhesive layer in the multilayers using digital signal processing. The reflected signals from the multilayers come out interval of the peaks in the power cepstrum. In the experiment, the adhesive layers of settled thickness using epoxy were formed. The reflected signals from the multilayer is detected by pulse-echo method and power cepstrum is processed for enhancement of visibility.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.73-79
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• 2018

In this paper, TM(transverse magnetic) scattering problems by a conductive strip grating between a double dielectric layer are analyzed by applying the PMM(point matching method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, the scattered electromagnetic fields are expanded in a series of Floquet mode functions, and the conductive boundary condition is applied to analysis of the conductive strip. The most normalized reflected powers of the sharp variations in minimum values are scattered in direction of the other angles except incident angle. Generally, in the case of numerical analysis except for reflection and transmission power in free space, as the dielectric constants of the double dielectric layer increases, the reflected power increases and the transmitted power decreases relatively, respectively. The numerical results for the presented structure of this paper having a grounded double dielectric layer are shown in good agreement compared to those of the existing papers.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.26-32
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• 2013

The earth reflection effect on the induced voltage by line source such as power line occurring induction inteference is analyzed to scrutinize how much it would reduce the induced voltage. Using hankel transformation including bessel function, directly calculation formulae for extracting a refelction coefficient is a most important technical application in this paper since the reflection coefficient on the earth cannot be deduced by a general coefficient calculation formulae according to a plain wave. The electric field is utilized to transform the electromagnetic field into an induced voltage. The composed efficiency to a source induction voltage by an earth reflection is about a range of 60~70% for the axis constellation of each object like observation point, source position and other material parameters.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.9A
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• pp.913-919
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• 2006

In this paper, TE(transverse electric) scattering problems by a resistive strip grating over grounded dielectric multilayers according to the strip width and grating period, the relative permittivity and thickness of dielectric multilayers, and incident angles of a TE plane wave are analyzed by applying the FGMM(Fourier-Galerkin Moment Method) known as a numerical procedure. The induced surface current density is simply expanded in a Fourier series by using the exponential function as a simple function. Generally, the relected power gets increased according as the relative permittivity and thickness of dielectric multilayers gets increased, the sharp variations of the reflected power are due to resonance effects that take place and were previously called wood's anomallies$^{[7]}$. To verify the validity of the proposed method, the numerical results of normalized reflected power for the uniform resistivity R = 0 as a conductive strip case show in good agreement with those in the existing paper.

• Journal of Advanced Navigation Technology
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• v.10 no.3
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• pp.198-204
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• 2006

In this paper, TE(transverse electric) scattering problems by a resistive strip grating on a grounded dielectric plane according to the strip width and grating period, the relative permittivity and thickness of dielectric layer, and incident angles of a TE plane wave are analyzed by applying the FGMM(Fourier-Galerkin Moment Method) known as a numerical procedure. The induced surface current density is simply expanded in a Fourier series by using the exponential function as a simple function. The reflected power gets increased according as the relative permittivity and thickness of dielectric multilayers gets increased, the sharp variations of the reflected power are due to resonance effects were previously called wood's anomallies[7]. To verify the validity of the proposed method, the numerical results of normalized reflected power for the uniform resistivity R = 0 as a conductive strip case show in good agreement with those in the existing paper.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.29-34
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• 2022

In this paper, thr H-polarized scattering problems by a resistive strip grating in a grounded double dielectric layer are analyzed by applying the PMM(point matching method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, the scattered electromagnetic fields are expanded in a series of Floquet mode functions, and the resistive boundary condition is applied to analysis of the resistive strip. The %error of the convergence of the reflected power according to the relative permittivity of the dielectric layer and the size of the number of rows in the square matrix was compared, as the size of the number of rows in the square matrix increased, the accuracy of the reflected power increased. As the resistivity of the resistive strip decreased, the thickness of the dielectric layers decreased, and the relative permittivity of the dielectric layers increased, the reflected power increased. The numerical results for the presented structure of this paper having a grounded double dielectric layer are shown in good agreement compared to those of the existing papers.

• Information Display
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• v.3 no.3
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• pp.20-29
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• 2002

본 소고에서는 개인용 휴대 전화나 PDA, 캠코더, 디지털카메라, 소형 PC나 휴대용 PC 등에 적용할 수 있는 소형 반사형 액정 디스플레이 시스템과 전면 광원 장치에 관한 기술들을 논의 하였다. 반사형 액정 디스플레이 시스템은 가볍고 얇으며, 저 비용으로 낮은 전력소모를 얻을 수 있다는 장점을 가지고, 고휘도화와 높은 콘트라스트, 넓은 시야각등을 목표로 많은 연구들이 진행되고 있다. 이러한 반사형 액정 디스플레이 시스템의 문제점들과 이를 해결하기 위해 제안된 주요 방법들을 소개하였고, 국내외 관련 연구 동향에 대해 기술하였다. 또한 전면 광원 장치용 도광판을 설계하기 위한 기법과 설계 결과를 제시하였다.