• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.161-164
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• 1998

광대역 주파수 상에서 외부로부터 입사하는 전자파를 산란시키지 않고 유전체 내부에서 흡수시키기 위해 유전체를 다층으로 배열하여 전파 흡수체를 최적 설계하고자 한다. 수직 및 여러 각도로 전파가 입사하는 경우 각 유전층의 두께, 유전 상수, 손실 탄젠트 등의 설계변수를 유전자 앨거리즘을 이용하여 최적화한다. 다극함수에서의 부분 초기화 유전자 앨거리즘의 성능 향상을 위해 부분 초기화율, 부분 초기화 시점, 스케일 인자의 변화에 따른 성능을 비교, 개선하여 흡수체 설계에 적용하였다.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.1
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• pp.43-50
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• 2003

전자산업과 전파통신기술이 고도로 발전함에 따른 전파 이용의 증대로 인해 전자파환경 EMI/EMS이 사회적 문제를 야기하고 있다. 이에 따라, CISPR(Comite Internationale Special des Perturbations Radioelectrique), FCC (Federal Communications Commissions) ANSI (American National Standards Institute)등의 기구는 EMI/EMC 대책을 위해 전파환경의 규정을 제정하고 있다. 또한 EMI/EMC 측정을 위한 전파무향실(anechoic chamber)용 전파흡수체는 20 dB 이상의 전파흡수능이 요구된다. 종래의 EMI 측정 주파수 범위는 30 MHz～l,000 MHz 이었으나 1998년 11월, CISPR11은 1 GHz~18 GHz를 추가하는 안을 받아들였다. 본고는 새로운 형태의 다층형 페라이트 전파흡수체를 제안하고 등가재료정수법을 사용하여 광대역 설계를 시도한 것이다.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.4
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• pp.445-450
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• 2007

An optimum design process of the broad-band multi-layered radar absorbing material, using genetic algorithm, is established for the radar cross section reduction of a complex target, which consists of multiple reflection structures, such as surface warships. It follows the successive process of radar cross section analysis, scattering center analysis, radar absorbing material design, and reanalysis of radar cross section after applying the radar absorbing material. It is demonstrated that it is very effective even in the optimum design of the multi-layer radar absorbing material. This results from the fact that the three factors, i.e.. the incident angle range, broad-band frequencies, and maximum thickness can be simultaneously taken into account by adopting the genetic algorithm.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.1
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• pp.70-78
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• 1995

In order to implement broadband RAM's(Radar Absorbing Materials) made up of multiple dielectricl layers, the design variables such as the dielectrci constaints, the depths and the loss tangents of dielectric are optimized. The wave impedances regarding the reflective wave are found in dielectrics, input impedances and reflection coefficients with multiple dielectric layers are derived from the transmission line circuit theory. Finally, minimum average reflective power and optimum design variables are obtained by applying the numerical technique, called modified Powell method. In case of four dielectric layers with inequality constraints in design variables, a quite favourable and feasible result with the total depth of 1.1 cm, the average reflective power of 0.85% over the bradband frequency range is obtained for a specific example.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.3
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• pp.17-24
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• 1997

Broad-band RAM's (Radar absorbing materials) are designed by multi-layered lossy dielectrics. The depth, the relative permittivity and the loss tangent of each layer are optimized in order to meet the required reflective power over the specified frequency range using a genetic algorithm. The reflection coefficients are calculated by the continued fraction method. A new population model of the partial initialization method during iterations is applied for the multi-modal functions to enhance the performance of the genetic algorithm. The optimal RAN's are designed by setting the relative permittivity and the loss tangent of the dielectrics as a funtion of the frequency over 5~20GHz.