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페이즈필드 설계법을 이용한 다중 유전체 구조의 RF 콜리메이터 설계
고주현,성홍경,김한민,박진우,유정훈 한국전산구조공학회 2018 한국전산구조공학회논문집 Vol.31 No.1
In this study, a collimator composed of multi-dielectric structures is designed using the phase field design method, a kind of topology optimization methods. It is also purposed to improve the mechanical-structural performance of a collimator by replacing previously used air regions with another dielectric material. Polypropylene and paraffin are selected as the dielectric materials for the design process taking manufacturability into account. The design objective is formulated by integrating the intensity of the electromagnetic field in the pre-determined target area to realize the collimating performance. The model for accurate numerical analysis was derived from the final result obtained from the design process through the simple cut-off method and it shows the improved performance of 105% compared with the free space wave propagation. For the designed model, the possibility of reverse transformation, the mechanical durability evaluation under the compression load, and the electromagnetic performance in the X-band range were also evaluated. 본 연구에서는 페이즈필드 설계법을 통한 다중 유전체로 구성된 콜리메이터 구조를 설계하였다. 제작 가능성을 고려하여 폴리프로필렌과 파라핀을 유전체 재질로 선정하였고, 측정영역의 전기장의 세기의 면적분으로 계산하여 이를 최대화하는 것으로 설계의 목적 함수를 설정하였다. 두 가지 유전체 재질을 이용하여 설계영역 내의 중공영역이 배제된 구조를 도출하였으며 컷오프를 통해 최종 형상을 모델링하였다. 수치해석을 통하여 설계된 다중 유전체 구조의 콜리메이터를 이용하는 경우 자유공간 내의 원형 전자기파 대비 측정영역에서 105%의 전기장 세기가 증가된 평행파를 생성하는 콜리메이터의 성능을 확인하였다. 설계된 모델의 수치해석을 통하여 콜리메이터의 역변환 가능성과 구조적 내구성의 증가를 확인하였고, X밴드 대역 전체에서의 성능을 평가하였다.
Optimal Shape Design of the Film-Coupled Nanoparticle using the Phase Field Design Method
이학용,성홍경,유정훈 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.4
Localized surface plasmon resonance (LSPR) occurs when an electromagnetic (EM) wave hits a metal nanoparticle. The interaction between a gold (Au) nanoparticle and a thin metal film produces a strong EM wave called as LSPR at the small gap between the nanoparticle and the film. The field strength of the LSPR increases dramatically as the distance between the Au nanoparticle and the film decreases. In this study, we focus on the field enhancement at the small gap by obtaining the appropriate shape of the Au nanoparticle. Since the shape or the size of a nanoparticle to enhance the LSPR is hard to be determined theoretically, the structural optimization method based on the phase field method is employed to design the shape of the nanoparticle. To obtain reliable results taking the small gap of 2 nm into account, we proposed a new filtering scheme based on a smoothed Heaviside function and applied it to nanoparticle design.