• Proceedings of the KIEE Conference
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• 2007.04b
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• pp.55-57
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• 2007

오일 변압기 내부의 절연물은 절연지, 프레스보드, 광유 또는 식물유가 주로 사용되고 있다. 사용 기간과 과부하 조건에 따라 열화정도가 달라질 수 있으며, 내부 절연물의 열분해 및 가수분해로 인해 수분은 자연스럽게 생성될 수 있다. 생성된 수분은 절연을 약하게 하는 주된 요인으로 작용해 기기의 고장 또는 정전을 초래할 수도 있다. 본 논문에서는 변압기 내부 절연물의 주파수응답 특성과 절연상태 값을 바탕으로 변압기 내부를 전기적 소자로 등가화하였다. 그 후 등가화된 회로를 이용해 회복전압법의 원리에 따라 EMTP 프로그램을 활용해 분극특성을 모의하였다. 실제 측정 값과의 비교를 위해 보고된 문헌의 데이터를 활용하였고, RVM을 이용한 실측값과 유사한 결과를 얻게 되었다. 따라서 본 시뮬레이션에 활용된 전기적 소자값을 변경함으로서 내부 절연물의 열화정도에 대한 기대 파형을 예측할 수 있는 유용한 도구로 활용될 수 있음을 확인하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.9
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• pp.957-967
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• 2008

In this paper, we propose the prediction algorithm of radiation emission from the PCB in an enclosure with a rectangular aperture. PCB scanner is used to measure the near field, which is substituted with an equivalent electric dipole source. Green function and Fourier transform are utilized to represent the electromagnetic fields within and outside the enclosure, respectively. The radiation emission is estimated by using the mode matching technique and surface equivalent theorem. The theoretical results are compared with the measurement to check the accuracy of our analysis.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.261-267
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• 2015

The eigenvalue problems involving the diffraction of waves by multi-layered grating configurations can be explained by rigorous modal expansion terms. Such a modal solution can be represented by equivalent transmission-line networks, which are generalized forms of simple conventional circuits. This approach brings considerable physical insight into the grating diffraction process of the fields everywhere. In particular, the transmission-line representation can serve as a template for computational algorithms that systematically evaluate dispersion properties, radiation effects and other optical characteristics that are not readily obtained by other methods. To illustrate the validity of the present rigorous approach, the previous research works are numerically confirmed and the results agree well each other.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.5
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• pp.1342-1348
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• 1998

The major limitation of MOM solution has alaways been the computer CPU time and storage size, needed to carry out the impedance matrix computation. A new formulation technique using Sorce Superimposion method is presented in order to cut down computerstorage requirements and CPU time based on the equivalence principle and induction theorem. The numerical results are shown to give good agreement to those calculated by the conventional method and also application example is presented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.548-551
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• 2003

JSize is a Java equivalent of the Unix size program. The Unix size program analyses an executable file and estimates the size of code and data segment when the file is loaded on memory. Likewise, JSize analyze a Java class file and estimates the size of class area when the file is loaded on memory. This paper presents the principles necessary to estimate the class area size with the information obtained from a class file. An experimental result is included to show the accuracy of estimation the JSize provides.

• The Journal of the Korea Contents Association
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• v.4 no.2
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• pp.28-35
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• 2004

The improvement of a near-field measurement for an antenna is investigated. We propose the formula of a circular cylindrical scanning based on the Cartesian coordinate. Proposed algorithm for the circular cylindrical Scanning is compared with the exact solution for a Hertzian dipole antenna, thus confirming that our approach is useful for most practice measurements.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.11
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• pp.20-24
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• 1990

A fast convergent solution to the scattering problem of a transverse electric (TE) plan wave by a periodic strip grating with a dielectric slab is considered. The present method follows from an expansion of the equivalent surface magnetic current placed over the shorted slot according to the equivalence principle in a series of Chebyshev polynomials satisfying the appropriate edge condition. To examine the accuracy and convergence of the present method, the numerical results are calculated for the reflection and transmission coefficients and compared with other results available in the literature.

• 전기의세계
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• v.45 no.12
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• pp.12-19
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• 1996

본고에서는 전기기기의 해석 및 설계에 필요한 여러 기술들을 간략히 소개하고자 한다. 설계의 초기 단계에서 시스템의 전체적인 기본 특성 파악에 주로 사용되는 자기 등가회로에 의한 방법과 이산화된 모델에 수치 해석적 원리를 적용하여 보다 정확하고 국부적인 특성을 파악하는데 사용되는 수치 해석 방법을 중심으로 설명하고자 한다. 그리고, 위의 방법들로 해석, 설계된 연구 결과 및 동향과 앞으로의 전개 방향에 대해서도 고찰하고자 한다. 소개되는 연구 결과는 여러 가지 전기기기 중에서도 주로 메카트로닉스 분야에서 사용되는 영구자석 전동기와 유도기 및 영구자석 lifting 시스템 등을 중심으로 서술하고자 한다.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.125-128
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• 2000

가상적인 검출잡음을 가정하고 칼만 필타(Kalman Filter)를 고려하여 근사적 최적 레귤레이터의 특성에 가깝게 함으로써 견실 안정성을 회복할 수 있는 제어 시스템의 설계에 관하여 검토한다. 본 연구에서는 관측기를 이용한 최적 레귤레이터 계에 적분기를 결합한 견실제어계의 설계법을 나타내고 견실성을 회복할 수 있는 제어기의 파라미터 설정법을 나타낸다. 제어대상의 파라미터 변동에 의해서 생기는 등가인 외란을 억제하고 과도특성이 변하지 않는 제어 시스템을 모델 매칭의 원리에 기초하여 설계한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.4
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• pp.381-387
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• 2016

In this paper, the methodology applied to the improvement of stress analyses is extended to free vibration and buckling analyses. The essence of the methodology is the Saint-Venant's principle that is applicable to beam and plate models. The principle allows one to dimensionally reduce three-dimensional elasticity problems. Thus the methodology can be employed to vibration and buckling as well as stress analysis. First, the principle is briefly revisited, and then the formations of classical beam theories are presented. To improve the predictions, the perturbed terms (unknowns) are introduced together with the warping functions that are calculated by stress equilibrium equations. The unknowns are then calculated by applying the equivalence of stress resultants (i.e., Saint-Venant's principle). As numerical examples, cantilever and simply supported beams are analytically solved. The results obtained are compared with those of the classical beam theories. It is shown that the methodology can be used to improve the predictions without introducing shear correction factors.