• 전기학회논문지P
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• 제58권2호
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• pp.158-163
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• 2009

A shading ring in an AC solenoid plays an important role in reducing vibration and humming sound. Estimation of performance of the shading ring placed in a stator pole of the AC solenoid is not an easy task due to the difficulty in measurement of the current and flux linkage of the shading ring. In this paper, dynamic performance of an AC solenoid with a shading ring is analyzed through the simulation using electromagnetic analysis software and the results are verified by simple AC and DC voltage tests. Both the simulation and experimental results show that the shading ring in the AC solenoid not only increases pull force, but also reduces operation time, vibration and humming sound.

• Journal of Magnetics
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• 제17권4호
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• pp.291-297
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• 2012

This paper presents an efficient methodology for accurate reliability assessment of electromagnetic devices. To achieve the goal, elaborate surrogated models to approximate constraint functions of interest are generated based on the dynamic Kriging method and a hypercube local window. Then, the Monte Carlo simulation scheme is applied to the surrogate models. This leads to reducing computational cost dramatically without degrading accuracy of the reliability analysis. The validity of the proposed method is tested and examined with a mathematical example and a loudspeaker design.

• Journal of information and communication convergence engineering
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• 제16권3호
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• pp.197-202
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• 2018

This paper reveals the impact of the insertion of electromagnetic band gap (EBG) structures on the performance of circularly polarized (CP) patch-slot antenna with offset slot. Several optimizations are necessary to precise physical parameters in the aim to fix the resonance frequency at 3.2 GHz. The proposed antenna possesses lightweight, simplicity, low cost, and circular polarization ensured by two feeding sources to permit right-hand and left-hand circular polarization process (RHCP and LHCP). The measured results compared with simulation results of the proposed circularly polarized EBG antenna with offset slot show good band operations with –10 dB impedance bandwidths of 9.1% and 36.2% centered at 3.2 GHz, which cover weather radar, surface ship radar, and some communications satellites bands. Our investigation will confirm the simulation and experimental results of the EBG antenna involving new EBG structures.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.234-237
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• 2003

The absorption and the interference shielding of the electromagnetic wave problem have been a very important issue for commercial and military purposes. This study dealt with the simulation reflection loss for electromagnetic absorbing sandwich type structures in X-band(8.2Ghz~12.4GHz). Glass/epoxy composites containing conductive carbon blacks were used for the face sheets and styrofoams were used for the core. Their permittivities in X-band were measured using the transmission line technique. Simulation results of 3-1ayered sandwich type structures showed the reflection loss using the theory about transmission and reflection in a multi-layered medium.

• Journal of Magnetics
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• 제19권3호
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• pp.266-272
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• 2014

In this paper, we suggest reliability as a metric to evaluate the robustness of a design for the optimal design of electromagnetic devices, with respect to constraints under the uncertainties in design variables. For fast numerical efficiency, we applied the sensitivity-assisted Monte Carlo simulation (S-MCS) method to perform reliability calculation. Furthermore, we incorporated the S-MCS with single-objective and multi-objective particle swarm optimization algorithms to achieve reliability-based optimal designs, undertaking probabilistic constraint and multi-objective optimization approaches, respectively. We validated the performance of the developed optimization algorithms through application to the optimal design of a superconducting magnetic energy storage system.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.560-564
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• 2003

In this paper, we carried out performance analysis of mobile station with built-in antenna for PCS(Personal Communication System) band. The radiation patterns for antenna and mobile phone were simulated by using 3D simulation program, HFSS(High Frequency Structure Simulator) and SEMCAD(Simulation Platform for Electromagnetic Compatibility Antenna Design Dosimetry). We observed radiation pattern variation according to installation of LED(Light Emitting Diode) circuit and ground pattern. The radiation pattern of prototype mobile phone was measured, and the radio sensitivity was measured by using Agilent E5515C and chamber. The measured maximum antenna gain at 1.87GHz was 0.21dBi. The measured radio sensitivity of prototype mobile phone shows proper performances comparable to other models with external antennas.

• 한국정밀공학회지
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• 제15권10호
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• pp.165-171
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• 1998

An axial electromagnetic levitation system using attractive force is a highly nonlinear system due to the nonlinearity of materials, variable air gap and flux density. To control the levitating system with large air gap, a conventional PID control based on the linear model is not satisfactory to obtain the desired performance and the position tracking control of the sinusoidal motion by simulation results. Thus, sliding mode control(SMC) based on the input-output linearization is suggested and evaluated by simulation and experimental approaches. Usefulness of the SMC to this system is conformed experimentally. If the expected variation of added mass can be included in the gain conditions and the model, the position control performance of the electromagnetic levitation system with large air gap will be improved with robustness.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2003년도 춘계학술대회논문집
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• pp.15-18
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• 2003

전자파 산란해석 방법으로서 유한요소법, 경계요소법 및 모멘트법 등은 임의 구조를 한 산란체의 산란현상을 다룰 수 있다. 그러나 이러한 해석방법들은 정상 파동문제를 다루는데 편중되어 있어 시간영역에서의 비정상 파동문제를 해석하기 위해서는 여러 가지 제약이 따른다. 본 논문에서는 본질적으로 시간영역 해석방법인 TLM(Transmission Line Matrix)법을 이용하여 프레넬 렌즈의 산란특성을 해석하고 키르호프의 근사식과 PO(Physical Optics)법과 비교 검토하여 그 유효성을 검증한다.

• Journal of electromagnetic engineering and science
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• 제13권4호
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• pp.263-266
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• 2013

A novel compact and low-loss VHF bandpass filter is presented with enhanced stopband performance using metamaterial zeroth order resonator (ZOR) characteristics. An in-line ZOR filter is initially suggested and changed to have transmission zeros (TZs) due to source-load coupling for effective improvement of the isolation from UHF wireless channels. The proposed filter is smaller than 1/10 of the conventional filters in terms of size and has relatively very low insertion loss (< 1 dB for the electromagnetic (EM) simulation and < 3 dB for the measurement) and return loss (<-20 dB) in the passband due to the approximately 80% size reduction and the higher isolation in the stopband due to the TZs. The circuit and EM simulation are in good agreement with the measurements.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.704-710
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• 2018

For the optimal design of electromagnetic device involving uncertainties in design variables, this paper proposes a new reliability-based optimal design algorithm for multiple constraints problems. Through optimizing the nominal objective function and maximizing the minimum reliability, a set of global optimal reliable solutions representing different reliability levels are obtained by the multi-objective particle swarm optimization algorithm. Applying the sensitivity-assisted Monte Carlo simulation method, the numerical efficiency of optimization procedure is guaranteed. The proposed reliability-based algorithm supplying multi-reliable solutions is investigated through applications to analytic examples and the optimal design of two electromagnetic problems.