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휴대형 무선 단말을 위한 FERRITE-CORE LOOP ATENNA의 설계 제작
권원현,천경준,허선종,박한규 한국통신학회 1992 韓國通信學會論文誌 Vol.17 No.9
본 논문에서는 이동 통신용 소형 무선기기에 사용가능한 소형 Ferrite-core Loop 안테나를 설계 제작하고 그 특성을 고찰하였다. 안테나는 $10{\times}6{\times}15mm^3$의 크기를 갖는 loop 안테나 내부에 Ferrite core를 삽입하여 제작하였고 제작된 안테나는 $50\Omega$ 정합시 대역폭 (SWR 1.5이하)은 0.55 MHz, Q값은 280으로 동일 크기를 갖는 Loop 안테나 (BW=1.9 MHz, Q=81.4)에 비해 주파수 선택 특성이 우수하였다. 8 방향 방사특성시험 및 TEM Cell을 이용한 수신특성시험에서도 기존의 loop안테나에 비해 11dB이상 이득이 증가됨을 알 수 있었다. In this paper, ferrite-core loop antenna for portable radio receiver is designed and its characteristics are analyzed. Antenna is fabricated by inserting the ferrite core inside the planar conductor loop$(10{\times}6{\times}15mm^3)$. Bandwidth and Q factor of fabricated antenna measure 0.55 MHz and 280, respectively. These results show remarkable enhancement compared to the conventional loop antenna having the same physical dimension(BW=1.9MHz, Q=8.14). Experimental results show that the relative gain of the fabricated antenna is about 11 dB higher than that of the conventional antenna.
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정지혜,천경준,오용희,장훈상 한국품질경영학회 2017 품질경영학회지 Vol.45 No.4
Purpose: The purpose of this study was to evaluate the color stability of composite resins used for splinting teeth by comparing a self-cure resin cement (Superbond C&B, SB), a flowable composite resin (G-aenial Universal Flo A2, GU), and a composite resin exclusively used for splinting teeth (G-Fix, GF) before and after aging in NaOCl. Methods: Resin samples were fabricated to a size of 2 mm thickness and 8.5 mm diameter and light-cured with an LED light curing unit (G-Light, n = 12). Immediately after fabrication, CIE L*a*b* values of the resin samples were measured with a spectrophotometer (CM-5) as baseline. Then, the resin samples were immersed in 5% NaOCl at 60 ℃ and the color was measured after 23 hours every day for 4 days. Data were analyzed with one-way ANOVA followed by Duncan post hoc test (p<0.05), and color differences (ΔE) of resin samples before and after NaOCl aging were also calculated. Results: For SB, there were no changes in L* and a* values but changes were observed in b* values. For GU, there were no changes in L* and b* values but in a* values. For GF, changes were observed in L*, a*, and b* values. All resin samples showed highest ΔE between baseline and the 1st day of NaOCl immersion. ΔE of SB, GU, and GF was 4.6 – 5.8, 4.9 – 7.9, and 9.9 – 16.9, respectively. GF showed highest color change during NaOCl aging. Conclusion: The results of this color quality evaluation showed that the composite resin exclusively used for splinting teeth might be more vulnerable to color change during intraoral service.
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