• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.27-30
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• 2003

In this paper a new approach of digitalized ‘Takbon’ is introduced. By image signal processing, the letters which were written on stones can be deciphered. Epigraphic letter is detected by digital image device, digital camera. The two dimensional digital image is preprocessed because of sensor noise and detective turbulence. Color image is transformed into grey level. The letter image is analyzed in time/frequency domain. By the resultant analysis data decisive functions are calculated. Signal Processing techniques, such as scaling, clipping, digital negative, high/low filter, morphology and so on, provide algorithms that can extract letter from stones.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.881-884
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• 1999

In this paper, resonant frequency, electromagnetic field distribution, and resonant mode of a microstrip substrate-mounted dielectric resonator are investigated. A dielectric resonator is excited by the microstrip line. The data are obtained using the finite difference time-domain (FDTD) and compared with the experimental results and theoretical solutions the previous published paper.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.270-271
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• 2000

Among many optical modulators, we are interested in traveling-wave(TW) multiple quantum well(MQW) electro-absorption modulator which can be used for wide-band applications, covering DC to 30GHz or higher frequencies. In this study, we simulate a 1.3mm InGaAs/lnGaAsP TW MQW EAM using the 3D Finite Difference-Time Domain (FDTD) method. We identify that several geometric factors affect Microwave charateristics. Our calculated data provide useful information to optimize and fabricate ridge-type TW CPW EAM.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.6
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• pp.421-430
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• 2005

Brillouin time-domain analysis in optical fibres is a novel technique making possible a distributed measurement of temperature and strain over long distance and will deeply modify our view about monitoring large structures, such as dams, bridges, tunnels and pipelines, Optical fibre sensing will certainly be a decisive tool for securing dangerous installations and detecting environmental and industrial threats.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.319-324
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• 2001

An anatomical head and a multi-layered spherical head with a half-wave handset antenna have been analysed and compared using the Finite-Difference Time-Domain (FDTD) and the Eigenfuntion Expansion Method (EEM), respectively. The analysis shows that results from a simple spherical head with a half-wave antenna can be used to predict the main antenna radiation patters as well as estimates of the peak SAR in a handset user's head. Various representative design data are presented using a six-layered spherical head with a half-wave antenna at 900 MHz

• Bulletin of the Korean Mathematical Society
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• v.31 no.2
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• pp.309-318
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• 1994

The approach presented in this paper is based on the transformation of the Stefan problem in one space dimension to an initial-boundary value problem for the heat equation in a fixed domain. Of course, the problem is non-linear. The finite element approximation adopted here is the standared continuous Galerkin method in time. In this paper, only the regular case is discussed. This means the error analysis is based on the assumption that the solution is sufficiently smooth. The aim of this paper is the existence of the solution in a finite Galerkin system of ordinary equations.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1126-1127
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• 1999

연산자 분리 시영역 모델을 이용하여 광섬유 커플러 ADM(add-drop multiplexer)의 필터링 효과를 분석하였다. 이 모델은 방향성 결합기나 브래그 격자를 포함하는 소자의 해석에 유용하다. 본 논문에서는 비대칭 구조를 고려했으며 결합계수, 코어의 반경, 개구수, 굴절율 변조 등의 파라미터를 이용하여 최적의 필터링 효과를 얻기 위한 구조를 설계하였다.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.397-400
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• 2006

본 논문에서는 DSP를 이용하여 코히어런트 레이더에 사용될 수 있는 확장성이 용이한 디지털 펄스 압축기를 시간영역에서 설계하고 그 내용을 분석하였다. 수신 거리 셀 및 FIR 필터 탭(tap) 수에 따른 펄스압축 연산시간을 ADSP21060을 사용하여서 분석함으로써, 설계하고자하는 레이더 시스템 요구 파라미터 들이 정해지는 경우 펄스압축기 구성에 소요되는 DSP의 수행 기능과 소요 수를 쉽게 예측할 수 있도록 운용특성을 분석하였다.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.600-602
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• 2000

In this paper, channel dropping filters made of microring structure are analyzed by using a finite difference time domain(FDTD) method with Berenger's perfectly matched layer(PML) absorbing boundary condition.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.146-152
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• 2002

In this study, the singular thermal stresses induced during cooling down from high temperature to room temperature have been analyzed for the viscoelastic thin layer. The time domain boundary element method has been employed to investigate the behavor of stresses for the whole interface. Within the context of a linear viscoelastic theory, a stress singularity exists at the point where the interface between the elastic substrate and the viscoelastic thin layer intersects the free surface.