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마이크로스트립 라인-프로브 급전구조를 갖는 광대역 패치 안테나의 설계
박종열,이윤경,윤현보 한국전자파학회 2002 한국전자파학회논문지 Vol.13 No.7
본 논문에서는 중심주파수가 5.8 GHz에서 동작하는 새로운 급전구조를 갖는 광대역 마이크로스트립 패치 안테나를 설계 및 제작하였다. 제안된 새로운 급전구조인 마이크로스트립 라인-프로브 급전구조는 광대역 특성을 가지며, 안테나의 패치 크기를 줄일 수 있다. 광대역 특성을 확인하기 위해 기존의 프로브 급전 마이크로스트립 패치 안테나와 비교하였으며, 그 결과 대역폭은 34.5 % 증가하였으며, 패치의 크기는 45 % 축소되었다. The design of broadband patch antenna with the new feeder structure is proposed in this paper. The antenna operates in the center frequency 5.8 GHz. Proposed the new feeder structure has also broadband characteristic and reduced antenna size. To confirm broadband characteristic, compared with probe feeder antenna. After designing and manufacturing, the antenna bandwidth enhanced by 34.5 % and the patch size reduced by 45 %.
朴鍾烈 영남이공대학 1981 論文集 Vol.10 No.-
It is one of the weak point of cement mold that, at low temperture, delay of coagulating rreaction of cement comes to lengthen out the strip time. So it is necessisary using hardening accelerator in winter. In order to improve the slowhardening of cement sand, Cacl_2·NaOH·Al Powder can be added as hardening accelerator. At 5℃ sand temperature, strip time of ordinary portland cement sand was 12hours. But adding CaCl_2(2%) or NaOH(1%) shortened strip time to less then 3 hours. NaOH was more efficient accelerator than CaCl_2. Its addition amount was small and it accelerated not only coagulating reaction but also hardening reaction of cement. Al powder was so excellent accelerator that adding small amount (0.1%) with NaOH (1%) shortened strip time to 1 hour. But it is difficult to use Al powder because bench life was too short to establish molding time. Then it can be efficiently used under intense cold atmosphere with NaOH to shorten strip time.