• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1434-1435
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• 2008

In this paper, we propose a method that applies Vector Fitting(VF) and Adaptive Frequency Sampling(ASF) technique to the equivalent circuit model for RF passive components. VF and ASF schemes are implemented to obtain the rational functions. S parameters of the equivalent circuit model is compared to those of EM simulation in case of the microstrip structure with coupled bandpass filter.

• 대한의용생체공학회:의공학회지
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• 제11권2호
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• pp.195-202
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• 1990

The hypothesis of asymmetric resistance to explain the phenomenon of lung hyperinflation (LHI) during hlgh frequency ventilation (HFV) was quantitatively studied. LHI was predicted by modeling the ism-volume pressure-flow (IVPF) data from 5 human subjects using the empirical Rohrer's equation. Non-steadiness during HFV was compensated by em- ploying recently proposed volume-frequency diagram. Tidal volume and ventilation frequency were 100 ml and 20 Hz, respectively. Airflow pattern was a symmetric sinusoid. The predic- tion results of mean pressure drop across the airways were averaged for those 5 subjects, and compared with zero by one-sided student's t-test. A marginally significant (P<0.1) increase in mean pressure drop was observed during HFV at low lung volumes (below FRC) , which could increase mean lung volume up to one liter When the lung volume was above FRC, no significant LHI (P >0.25) was resulted. LHI seemed to be inversely related to the lung volume. These results recommend to clinically apply HFV only at lung volumes above FRC.

• Journal of electromagnetic engineering and science
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• 제11권3호
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• pp.156-160
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• 2011

We have proposed and analyzed an equivalent circuit for a magnetically coupled wireless power transmission (WPT) system between two loop resonators by considering its coupling coefficient and radiation-related parameters. A complete formulation is provided for all the necessary circuit parameters. The mechanism of radiation loss is sufficiently explained. The circuit and electromagnetic (EM) simulation results have been shown to be in good agreement. Based on the proposed circuit formulation, a specific load impedance for maximum WPT efficiency was found to exist. The proposed modeling of the WPT in terms of circuit characterizations provides sufficient insight into the problems associated with WPT.

• Journal of electromagnetic engineering and science
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• 제10권4호
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• pp.219-223
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• 2010

Based on a provided closed-form wireless power transmission (WPT) efficiency formula, which may be used for any value of load, we have analyzed the WPT efficiencies between two metamaterial-inspired loop antennas in various aspects. Due to the modeling based on low frequency circuit theory, the provided formula at the center resonant frequency has been found to be accurate until when the distance between the two loop antennas increases to 15 cm (about $\lambda_0/6$ at 300 MHz). When the two loops get closer, the resonant frequency has been found to split into two in theory, simulations, and measurements. The EM-simulated and measured efficiencies at new resonant frequencies are 60.9 % and 46.3 %, respectively, at d=15 cm. With two extra rings around the loops, the maximum efficiency is enhanced to 93.7 % at d=15 cm. The effect of the additional two rings is about 30 %.

• 전기학회논문지
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• 제58권2호
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• pp.363-368
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• 2009

In the paper, we confirmed improvement Noise figure of the entire RF front-end using spiral inductor with PGS(Patterned Ground Shield) and current bleeding techniques. LNA design is to achieve simultaneous noise and input matching. Spiral inductor in input circuit of LNA inserted PGS for betterment of Q-factor. we modeling inductor using EM simulator, so compared with inductor of TSMC 0.18um. We designed and simulation the optimum structure of PGS using Taguchi's method. We confirmed enhancement of noise figure at LNA after substituted for inductor with PGS. Mixer designed using current bleeding techniques for reduced noise. We designed LNA using inductor with PGS and Mixer using current bleeding techniques, so confirmed improvement of noise figure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.854-857
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• 1998

에너지관리, 제어 시스템(EMS)은 전력계통의 실시간 제어 및 총체적인 관리를 최대화하기 하여 컴퓨터 및 통신 시스템으로 구축된 제어시스템이다. 본 EMS의 주요특성은, 첫째 상당히 빠른 속도로 발전되는 컴퓨터 및 통신 기술들을 수시로 수용할 수 있는 기능, 둘째 상대적으로 지속적이며 오래토록 사용되는 수학적인 알고리즘 및 Buiness Rule들을 처리하는 소프트웨어를 급변하는 Computing 환경에서 적응해 갈 수 있는 기능, 셋째 Heterogenous한 시스템에 접속시킬 수 있는 Database를 갖추었다. 끝으로, 대형 전력계통의 Modeling과 이에 부합하는 실시간 Data로 자동화된 전력계통 실시간 운영상의 결과들을 해석 및 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.605-607
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• 2000

Although Equvalent Magnetic Circuit (EMC) method. Using lumped parameter and numerical analysis method are widely used for electric machine analysis. these are neither always accurate enough nor sometimes available to easily use. Moreover three dimensional finite element method (3D-FEM) is inherently unsuitable for electric machine performance evaluation due to its poor computational efficiency, such as too long calculation time and difficulty in modeling for analysis. In this paper, Nonlinear Equivalent Magnetic Circuit (NEMC) method in combination with 2D-FEM is proposed to analyze the electric machine requiring 3D-FEM, and this method applys to torque evaluation for rotary actuator of Electro Magnetic Electronic Controller Power Steering (EM-ECPS).

• Journal of electromagnetic engineering and science
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• 제15권1호
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• pp.26-30
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• 2015

In this paper, a simple equivalent circuit model for a defected ground structure (DGS) microstrip line with stepped impedance slot-lines in the ground plane is presented. In addition, an analytic expression for the resonance frequency of the proposed structure is derived. In equivalent circuit modeling, the capacitance and the inductance of the resonance circuit are evaluated from the dimensions of the etched pattern in the ground plane. The resonance frequencies calculated from the proposed method are compared with those obtained with an electromagnetic (EM) simulation.

• 지구물리와물리탐사
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• 제23권4호
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• pp.223-229
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• 2020

소형 루프 전자탐사법은 효과적인 물리탐사법으로 다양한 목적으로 천부 조사에 널리 사용되고 있다. 소형 루프 전자탐사에서는 기하학적 수직탐사와 주파수 수직탐사가 적용되고 있으나, 주파수 수직탐사의 경우 그 유효성 대하여 논란이 지속되고 있다. 이 연구에서는 소형 루프 전자탐사에 대한 1차원 모델링을 통하여 기하학적 수직탐사와 주파수 수직탐사의 유효성을 검증하고자 하였다. 수치 실험 결과 기하학적 수직탐사는 효과적으로 지하의 심도에 따른 지하의 정보 해석이 가능한 것으로 나타났다. 반면 주파수 수직탐사는 송수신 간격이 비교적 클 경우, 즉 유도상수가 크다는 조건을 만족해야만 유효한 해석이 가능하며, 그렇지 못할 경우 하부 지층의 정보해석이 불가능한 것으로 나타났다.

• 응용통계연구
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• 제21권3호
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• pp.361-375
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• 2008

본 논문에서는 패널의 일부를 규칙적으로 교체하는 4-8-4 교체표본설계에서 발생할 수 있는 항목 무응답을 대체하는 방법에 대하여 연구하였다. 특히 소득이나 취업과 같이 민감한 질문에 대하여 발생할 수 있는 무응답에 대하여 무시할 수 없는 무응답(nonignorable nonresponse) 체계하에서 발생하는 무응답을 가정하였다. 무응답들의 대체방법으로 모형에 기반한 대체방법을 고려하였으며 베이지안 방법을 이용하여 사후확률밀도함수를 최대화하는 최대사후우도추정량(maximum posterior likelihood estimator)을 구하였다. 그리고 대체된 자료를 이용하여 면접시점이 달라질 때 발생하는 편향을 추정하였으며 추정된 편향을 제거한 후 연속적인 두 조사기간에서의 각 칸의 확률과 고정된 시점에서의 주변확률을 계산하였다. 모의실험을 통해 최종적으로 도출된 결과를 평균제곱오차와 편향의 관점에서 비교하였다.