• 한국정보통신학회논문지
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• 제14권10호
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• pp.2310-2316
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• 2010

이 논문에서는 형식 검증(formal verification)의 한 분야인 모델 검증(model checking)에 재타이밍(retiming) 기법을 적용하는 방법에서 대해 연구하였다. 재타이밍은 주어진 회로의 레지스터들을 재배치함으로써, 입출력 동작을 바꾸지 않으면서 전이 관계(transition relation)을 변환할 수 있는 기법이다. 이러한 재타이밍을 이용하면 모델 검증을 더 효율적으로 수행하도록 회로를 바꿀 수 있다. 이 논문에서는, 레지스터의 개수와 전이 관계의 특성을 반영한 cost 함수를 제안하고, 재타이밍으로 얻을 수 있는 회로 구조들을 효율적으로 탐색하는 heuristic annealing 알고리즘을 개발한다. 제안된 방법이 모델 검증의 성능을 향상시킬 수 있음을 실험 결과를 통해 보여주었다.

• 대한전자공학회논문지
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• 제9권3호
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• pp.9-16
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• 1972

본논문은 "s"를 변환함수로 하는 GIC회로가 자이레이터와 마찬가지로 인덕터를 RC능동회로로서 실헐할 수 있고, 또 임의의 안정한 전달함수가 GIC를 포함한 2단자대회로의 open-circuit voltage ratio로서 실현될 수 있음을 밝힌 것이다. 트랜지스터를 사용하여 GIC회로를 구성함에 있어시 트랜지스터의 nullator-norator model이 적어도 10kHz 이하의 주파수 범위에서 훌륭하게 적용될 수 있음이 밝혀졌다. GIC를 사용한 회로합성법의 특징은 다음괴 같다. 첫째로, 임의의 안정한 전달함수는 대단히 단순한 회로구성을 되풀이함으로서 체계계적으로 또 기계적으로 실현될 수 있다. 둘째로, 전체 회로에 있어서 GIC를 제외한 모든 회로요소는 저항뿐이다. 셋째로 n차의 전달함수를 실현하는데 있어서 필요한 콘덴서의 수효는 n이며, 이것은 가능한 가장 적은 수효라고 믿어진다.

• 전기학회논문지
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• 제58권11호
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• pp.2168-2174
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• 2009

Electrical railway system consists of rolling stock, track, signal and streetcar line system. Track circuit system is a vital system due to checking the location of trains. Track circuits are divided by using frequency and isolated electrically. Currently, there is not a regulation for the distance between track circuits using identical frequency. In case of installing additional track circuits in large stations or marshalling yard, the problem which is that the signal is not exactly transmitted to the track circuit occurs due to the mutual interference. In other words, the track circuit properly is not operated on account of wrong induction current by the mutual inductance between track circuits. In this paper, we suggest the electrical model between track circuits and numerically calculate demanded parameters in electrical model. The distance between track circuits satisfying the mutual inductance which does not happen to the mutual interference phenomenon is presented about the distance of track circuit. It is proved by using Matlab and PSpice program as the amplitude of mutual induced current.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.548-551
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• 2004

Magnetostrictive actuators have seen increasing use in fine positioning system because it has many advantages such as friction free, resolution of ${\mu}{\textrm}{m}$ or nm scale, and powerful output force. Usually, the magnetic circuit of magnetostrictive actuator has components which are flux return path, coil, and magnetostrictive material. It is classified in two types according to existence of the permanent magnet. The magnetic circuit having optimal performances transfer magnetic field which is obtained by providing input current at coil without energy loss. This paper described mathematical model of magnetic circuit for getting design variables. The modeling equation is obtained from the relations between flux and reluctance of the magnetic equivalent circuit. Also, finite element analysis has been used to study the performance of magnetic circuit according to change of design variables such as existence and shape of the permanent magnet, flux return path etc. The modification of dimensions enables us to optimize magnetic circuit.

• 전기학회논문지
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• 제60권2호
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• pp.301-308
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• 2011

This paper deals with the coupled electromagnetic-mechanical field analysis for short-circuit electromagnetic force of the dry-type transformer. The short-circuit currents are calculated using external circuit in accordance with short-circuit test equipment. According to short-circuit current, the generated magnetic leakage flux density in dry-type transformer model is calculated by finite element method. The radially-directed electromagnetic forces in windings are calculated using electromagnetic field analysis and then axially-directed electromagnetic forces in windings are calculated using electromagnetic-mechanical field analysis. The calculated axially-directed electromagnetic forces in high voltage winding are compared to those of measured ones and showed good agreement with experimental results.

• 대한전자공학회논문지SD
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• 제41권6호
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• pp.91-98
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• 2004

본 논문은 일반적인 SPICE 시뮬레이터에서 사용 가능한 PCB 평판 해석 모형을 제안한다. 제안된 모형은 주파수에 따라 증가하는 두 가지 손실, 즉, 표피 손실과 유전 손실의 영향을 반영한다. 평판은 메시(mesh) 구조로 조각을 낸 후, 각각의 단위모형은 전송선 소자와 손실 모형을 이용하여 모형화된다. 손실 모형은 DC 손실을 위해서 하나의 저항이 요구되고, 표피 손실을 위해 직렬 RL ladder 회로, 유전 손실을 위해서 직렬 RC ladder 회로가 요구된다. 제안된 모형의 검증을 위해 주파수 가변저항을 사용한 SPICE ac 해석결과를 통해 비교하고, 전형적인 데스크탑 PC용 FR4 4층 PCB 적층 구조를 만들어 VNA 측정치와도 비교할 것이다. 이 모형은 RLGC 수동 소자들로만 구성되므로 주파수 영역 및 시간 영역에서도 다양한 선형/비선형 소자들과 결합하여 과도 해석이 가능하다.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1759-1768
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• 2018

The energy density, power density and ohm resistance of battery change significantly as results of battery aging, which lead to decrease in the accuracy of the equivalent model. A parameter identification method of the equivale6nt circuit model with 3 R-C branches based on the test database of battery life cycle is proposed in this paper. This database is built on the basis of experiments such as updating of available capacity, charging and discharging tests at different rates and relaxation characteristics tests. It can realize regular update and calibration of key parameters like SOH, so as to ensure the reliability of parameters identified. Taking SOH, SOC and T as independent variables, lookup table method is adopted to set initial value for the parameter matrix. Meanwhile, in order to ensure the validity of the model, the least square method based on variable forgetting factor is adopted for optimizing to complete the identification of equivalent model parameters. By comparing the simulation data with measured data for charging and discharging experiments of Li-ion battery, the effectiveness of the full life cycle database and the model are verified.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권3호
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• pp.267-271
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• 2005

This paper deals with two kinds of novel shape switched reluctance motors (SRM) with magnetic barriers in order to improve operating performances of prototype. The magnetic barriers make rotor poles more saturated, and consequently inductance profiles are distorted. The changed inductance affects input current shape and eventually torque characteristics. In order to analyze the complicated flux pattern of the SRM with magnetic barriers and its terminal characteristics simultaneously, coupled field circuit modeling method is used. The finite element method is used to model the nonlinear magnetic field, and coupled to the circuit model of the SRM overall system. After experimental results are presented to prove the accuracy of the method, the several analysis results are compared, and the improved rotor shape is presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.370-374
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• 1991

This paper presents a static circuit model for static ant dynamic simulation of induction motors and identification of motor parameters. Instead of usual T-circuits, equivalent ${\pi}$-circuit has been proposed so that power Inputs into motor terminals can very easily calculated with very well known load flow method. It has been shown that, with wide range variation of applied voltage and frequency, successful static simulations can be performed and further the proposed static model can be used to simulate dynamic characteristics. Finally it is shown also that motor parameters can easily be identified based on the proposed static circuit.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.562-564
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• 1994

IGBT devices have the best features of both power MOSFETs and power bipolar transistors, i. e., efficient voltage gate drive requirements and high current density capability. The interaction of the IGBT with the load circuit can be described using the device model and the state equation of the load circuit. The protection circuit requirements are unique for the IGBT and can be examined using the model.