• Journal of Navigation and Port Research
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• v.30 no.2
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• pp.161-166
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• 2006

In order to construct an Anechoic Chamber satisfying international standards for EMI testing, it has been recognized that the absorption characteristics of the EM wave absorber must be higher than 20 dB over the frequency band from 30 MHz to 18 GHz. In this paper, an EM wave absorber with super wide-band frequency characteristics was proposed and designed in order to satisfy the above requirements by using the Equivalent Material Constant Method(EMCM) and Finite Difference Time Domain(FDTD). The proposed absorber is to attach a pyramidal absorber onto a hemisphere-type absorber on a cutting cone-shaped ferrite. As a result, the proposed absorber has absorption characteristics higher than 20 dB over the frequency band from 30 MHz to more than 20 GHz.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.229-229
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• 2012

It is significant issue to control the unwanted transverse electric (TE) modes in the vacuum chamber for preventing the position reading noise from the beam position monitor (BPM) of storage ring. We introduce shunt structure to control the frequency distribution of TE resonance modes excited in the vacuum chambers of the Pohang Light Source II (PLS-II). The design of shunt structure is performed using the full three dimensional finite-difference time-domain (FDTD) simulation. It is verified that the sympton of the BPM noise is not oberved up to the beam current of 190 mA in the commmissioning of PLS-II.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.239-239
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• 2013

The peak klystron power for the PAL (Pohang Accelerator Laboratory) XFEL (X-ray Free Electron Laser) is up to 80 MW which is higher than that of PLS-II LINAC. To prevent the RF breakdown such a high power operation, some of RF components need to be redesigned to reduce the surface electric field gradient to be less than the breakdown gradient at the vacuum-metal surface. For instances, the redesign of the Stanford Linear Accelerator Energy Doubler (SLED) system, the directional coupler and 3dB power splitter using the finite-difference time-domain (FDTD) simulation will be presented.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.405-410
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• 2014

In this paper, we compare the quality of images reconstructed by a conventional delayed-sum (DS) algorithm and radiation pattern-based DS algorithm. In order to evaluate the quality of images, we apply the target-to-clutter ratio (TCR), which is commonly used in synthetic aperture radar (SAR) image assessment. The radiation pattern-based DS algorithm enhances the TCR of the image by focusing the target signals and preventing contamination of the radar scene. We first consider synthetic data obtained through GprMax2D/3D, a finite-difference time-domain (FDTD) forward solver. Experimental data of a 2-GHz bandwidth stepped-frequency signal are collected using a vector network analyzer (VNA) in an anechoic chamber setup. The radiation pattern-based DS algorithm shows a 6.7-dB higher TCR compared to the conventional DS algorithm.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.183-186
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• 2000

We analyzed the cross-shaped microstripline-fed slot antenna with the reflector using FDTD(Finite-Difference Time-Domain) method in this paper. The proposed antenna uses RR Duroid-5880 substrate(relative permittivity 2.2 and height(1.578 mm) of dielectrics), and compares the optimized results of other kind substrates. The maximum bandwidth of the proposed antenna is from 1.91 GHz to 5.21 GHz, which is approximately 1.437 octave for the VSWR $\leq$ 2. It was found that the bandwidth of the antenna depend highly on the length of the horizontal and vertical feedline as well as the offset position of the feedline. The experimented data for the VSWR and the radiation pattern of the antenna are also represented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.214-217
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• 2001

Microwave continuous drier system mostly uses the ISM frequency band(915MHz or 2450MHz). It dry the material off from it's inside by the electromagnetic wave. The structure whose openings is needed for dry system to continuously feeds a materials into the system. So it is too difficult to shield the leakage of electromagnetic energy through the apertures. In this paper, we designed microwave continuous drier structure which operates at 2450MHz and analyzed the field distributions at the internal and external region of the structure.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1220-1223
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• 2009

The effect of silver (Ag) nano-particles on OLEDs was investigated by using a finite difference time domain (FDTD) tool. The proposed OLEDs employed Ag nanoparticles thermally deposited in a high vacuum on a cathode. The emission rate of the exciton was improved by 1.8 fold compared to the conventional OLEDs without Ag nano-particles. Less spacing between the dipole source and the Ag nano-particles resulted in a larger emission rate of the exciton in the OLED with nano-particles. The size of the Ag nano-particles was proportional to the emission rate of the exciton in a range of nano-meter scale of nano-particles. The enhancement of the emission rate of the exciton due to Ag nano-particles caused the improvement in the efficiency of the proposed OLED.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2174-2176
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• 2000

FDTD(Finite Difference Time Domain) 방법을 적용하여 마이크로웨이브 오븐 내부의 전자기장을 해석하였고, 적외선사진을 통하여 실험과 비교 검증하였다. 부하의 종류와 형태에 따른 전자기장의 패턴 변화를 고찰하였고, 여러 가지 포밍형태와 오프닝 형태에 따른 전자기장의 패턴을 적외선 사진과 비교하였다. 표면 보정 기법을 적용하여 부하표면에서의 전자파 패턴을 보다 정확히 예측할 수 있었으며, 또한 마그네트론의 공진 주파수에 따른 전자파 파워 패턴의 변화를 살펴 보았다. 이와 같이 개발된 마이크로 웨이브 오븐 내부의 전자파 해석 프로그램을 이용하면, 균일 가열 성능 향상을 위한 마이크로웨이브 오븐의 캐비티 설계 기간을 크게 단축할 수 있을 것으로 생각된다.

• Journal of the Optical Society of Korea
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• v.16 no.4
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• pp.432-442
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• 2012

In this paper, we propose, analyze and simulate the performances of some new plasmonic logic gates in two dimensional plasmonic waveguides with nanodisk resonators, using the numerical method of finite difference time domain (FDTD). These gates, including XOR, XNOR, NAND, and NOT, can provide the highly integrated optical logic circuits. Also, by cascading and combining these basic logic gates, any logic operation can be realized. These devices can be utilized significantly in optical processing and telecommunication devices.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.87-91
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• 2019

As a highly conductive and transparent electrode, ITO/Ag/ITO multilayers are fabricated using an in-line sputtering method. Optimal thickness conditions have been investigated in terms of the optical transmittance and the electrical conductance. Considering the optical properties, in this study, the experimental characteristics are analyzed based on theoretical phenomena, and they are compared with the simulated results. The simulations are based on the finite-difference-time-domain (FDTD) method in solving linear Maxwell equations. Consequently, the results showed that ITO/Ag/ITO multilayer structures with respective thicknesses of 39.2 nm/10.7 nm/39.2 nm are most suitable with an average transmittance of about 87% calculated for wavelengths ranging from 400-800 nm and a sheet resistance of about $7.1{\Omega}/{\square}$.