• 한국안전학회지
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• 제29권4호
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• pp.180-183
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• 2014

The purpose of this study is to assess for scattering object for the missile ejection round due to analysis of the human body effectiveness safely. To achieve this goal the measurement method of scattering objects by comparative 2 measurement methods studied, the risk of scattering of the object is evaluated. Result of this study, applied in Europe and Japan, based on the safety criteria for the human body effectiveness when missile ejection round. data showed is not effectiveness to the operator's body safely. Data showed that satisfies the safety criteria for missile ejection round in Europe and Japan through the similarity for the case studies. In case of these safety criteria does not exist regulation in South Korea, this study will be referred as guidelines are considered.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권3호
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• pp.142-148
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• 2006

The resonances that contain the information on the properties of the scattering target can be used for target reconstruction approaches. The inverse scattering theory for the resonances has been applied to the problems of the scattering for a spherical, cylindrical dielectric objects and dielectrically coated conductors, shown reasonable results. Though by using this method the thickness and the dielectric constants of the target can be obtained from a determination of the spacing and of the widths of the scattering resonances, the radius of the target should be given. In this paper, we suggest the improved inverse theory combined with the resonance scattering theory to obtain the radius in addition to the dielectric constant of the target. The applications of this method for scattering problems of electromagnetic waves from cylindrical targets were accomplished, and it shows its validity.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.308-313
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• 2015

This paper describes a technique for complete identification of a two-dimensional scattering object and multiple objects immersed in air using microwaves where the scatterers are assumed to be a homogenous dielectric medium. The employed technique consists of initially retrieving the shape and position of the scattering object using a linear sampling method and then determining the electric permittivity and conductivity of the scatterer using adjoint sensitivity analysis. Incident waves are assumed to be TM (Transverse Magnetic) plane waves. This inversion algorithm results in high computational speed and efficiency, and it can be generalized for any scatterer structure. Also, this method is robust with respect to noise. The numerical results clearly show that this hybrid approach provides accurate reconstructions of various objects.

• 천문학논총
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• 제22권1호
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• pp.21-33
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• 2007

Ever since the identification of 6830 and 7088 features as the Raman scattered O VI 1032, 1038 resonance doublets in symbiotic stars by Schmid (1989), Raman scattering by atomic hydrogen has been a very unique tool to investigate the mass transfer processes in symbiotic stars. Discovery of Raman scattered He II in young planetary nebulae (NGC 7027, NGC 6302, IC 5117) allow one to expect that Raman scattering can be an extremely useful tool to look into the mass loss processes in these objects. Because hydrogen is a single electron atom, their wavefunctions are known in closed form, so that exact calculations of cross sections are feasible. In this paper, I review some basic properties of Raman scattered features and present detailed and explicit matrix elements for computation of the scattering cross section of radiation with atomic hydrogen. Some astrophysical objects for which Raman scattering may be observationally pertinent are briefly mentioned.

• 천문학회보
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• 제46권2호
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• pp.40.1-40.1
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• 2021

Hydrogen is the most abundant element in the universe, which is, in the cosmological context, attributed to its simplest structure consisting of a proton and an electron. Hydrogen interacts with an electromagnetic wave in astrophysical environments. Rayleigh scattering refers to elastic scattering, where the frequencies of the incident and scattered photons are the same. Rayleigh and resonance scattering is a critical role study Lyman Alpha objects in the early universe. The scattering causes the frequency and spatial diffusion of Lyα. In the case of Raman scattering, the energies of the incident and scattered photons are different. The photons near Lyβ convert to the optical photons near Hα through Raman scattering. The photon scattered by atomic hydrogen can carry both of the properties of the H I region and the emission region. I adopt a Monte Carlo approach to investigate the formation of the various spectral line features through Rayleigh and Raman scattering in highly thick media of atomic hydrogen. In this thesis, I present my works on radiative transfer involving the scattering processes between far UV photon and atomic hydrogen. I introduce scattering processes with atomic hydrogen and the spectral, spatial, and polarized information originating from the scattering.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.446-449
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• 1988

A spectral inverse technique, which was developed by applying the pulse basis moment method procedure on the direct scattering problem in the reverse sequence for the reconstruction of complex permittivity profiles inside inhomogeneous dielectric objects, is modified to be applicable to the moment method with series-expanded basis. By performing numerical simulations for various type of dielectric objects, it is demonstrated that this inverse technique provides close reconstruction of permittivity profiles. Futhermore, compared to the previous scheme of the pulse basis, the presented method is shown to reduce the computation cost, relative error of reconstructed permittivity profiles by averaging in each cell, and the ill-posedness inherent to this inverse scattering problem.

• 전자공학회논문지A
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• 제32A권2호
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• pp.31-37
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• 1995

A ray-based approach is developed to calculate the scattering from inhomogeneous dielectric objects. This approach is a natural extension of the "shooting and bouncing ray(SBR)" technique developed earlier for calculating the radar cross section of cavity structures and complex targets. In this formulation, a dense grid of rays representing the incident field is shot toward the scatterer. The curved trajectory, amplitude, phase and polarization of the ray fields inside the inhomogeneous object are computed numerically based on the laws of geometrical optics. The contributions of the exting rays to the exterior scattered field are then calculated by using the equivalence principle in conjunction with " a ray-tube integration" scheme. The ray-based approach is applied for the effect of an arcjet plasma plume on satellite reflector performance and backscattering from inhomogeneous objects.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권11호
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• pp.551-558
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• 2002

A time-domain combined field integral equation (CFIE) is presented to obtain the transient scattering response from arbitrarily shaped three-dimensional conducting bodies. This formulation is based on a linear combination of the time-domain electric field integral equation (EFIE) with the magnetic field integral equation (MFIE). The time derivative of the magnetic vector potential in EFIE is approximated using a central finite difference approximation and the scalar potential is averaged over time. The time-domain CFIE approach produces results that are accurate and stable when solving for transient scattering responses from conducting objects. The incident spectrum of the field may contain frequency components, which correspond to the internal resonance of the structure. For the numerical solution, we consider both the explicit and implicit scheme and use two different kinds of Gaussian pulses, which may contain frequencies corresponding to the internal resonance. Numerical results for the EFIE, MFIE, and CFIE are presented and compared with those obtained from the inverse discrete Fourier transform (IDFT) of the frequency-domain CFIE solution.

• 전기전자학회논문지
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• 제23권2호
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• pp.614-621
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• 2019

본 논문은 integral equation-fast Fourier transform(IE-FFT)과 block matrix preconditioner(BMP)를 이용하여 침투 가능한 구조물의 전자기 산란 문제를 다룬다. IE-FFT는 모멘트 법(the method of Moments : MoM)에 의해 형성된 행렬방정식의 해를 계산하기 위하여 반복법의 연산량을 상당히 개선할 수 있다. 또한 전기적으로 커다란 구조물로부터 형성된 행렬방정식에 BMP가 적용된 반복법을 적용하면 반복 횟수를 크게 줄여 행렬방정식의 해를 빠르게 계산할 수 있다. 수치해석 결과는 IE-FFT와 BMP를 적용하여 침투 가능한 구조물의 전자기 산란 문제를 빠르고 정확하게 계산할 수 있음을 보여준다.

• Journal of electromagnetic engineering and science
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• 제10권3호
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• pp.166-170
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• 2010

To numerically calculate electromagnetic scattering from the electrical-large three-dimensional(3D) objects, the high-frequency approaches have been usually applied, but the accuracy and feasibility of these geometrical and physical optics(GO-PO) approaches, to some extent, are remained to be improved. In this paper, a new framework is developed for calculation of the near-field scattering field of an electrical-large 3D target by using a multilevel fast multipole algorithm(MLFMA) and generation of radar images by using a fast back-projection(FBP) algorithm. The MPI(Message Passing Interface) parallel computing is carried out to multiply the calculation efficiency greatly. Finally, a simple example of perfectly electrical conducting(PEC) patch and a canonical case of Fighting Falcon F-16 are presented.