• 한국전자파학회논문지
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• 제21권4호
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• pp.371-380
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• 2010

CATR(Compact Antenna Test Range)은 실내에서 반사판을 사용하여 균일 평면파를 제공하는 시험 시설이다. 반사판의 가장자리에서 발생되는 회절 전계는 균일 평면파의 리플(ripple)을 증가시키는 요인이 되기 때문에 CATR에서는 서레이션(serration)을 반사판의 가장자리에 부착하여 균일 평면파의 리플을 낮추게 된다. 일반적으로 서레이션의 회절 전계는 이중 적분으로 표현되는 프레넬 회절식(Fresnel diffraction formula)을 사용하여 해석하고, 서레이션 구조는 프레넬 회절식의 이중 적분 영역에 적용시키기 위해 푸리에 급수로 표현한다. 본 논문에서 는 새로운 shark-fin 형태를 갖는 서레이션을 사용하였고, 제안된 서레이션에 인접한 서레이션의 높이에 차이를 주는 구조를 제안하였다. 기존 삼각형 구조의 서레이션과 새로운 shark-fin 구조의 서레이션을 비교하여 제안한 shark-fin 구조의 서레이션에서 quiet zone의 크기를 보다 넓힐 수 있음을 확인하였고, 인접 서레이션의 높이에 변화를 주었을 때 동일한 높이보다 리플이 낮아짐을 확인하였다. 따라서 본 논문에서 제안한 shark-fin 형태의 높이가 다른 서레이션 구조는 CATR의 시험 영역에 리플이 낮은 균일 평면파를 제공할 수 있을 것으로 생각된다.

• 한국치위생학회지
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• 제12권3호
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• pp.513-520
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• 2012

Objectives : In this study, contact angle and shore D hardness were measured, and a shark fin test was conducted after selecting five addition silicon(Blu-Mousse, BM; EXABITE II, EX; PERFECT, PF; Regisil$^{(R)}$ Rigid, RE; Silagum$^{(R)}$, SI) in order to figure out the properties of elastomeric interocclusal recording materials and reduce errors at interocclusal recording. 8) Methods : A contact angle was measured using a contact angle analyzer. After placing a drop of liquid on the surface of the specimens of interocclusal recording materials, a contact angle was photographed with a CCD camera on the equipment. In terms of a shark fin test, interocclusal recording materials were mixed for the time proposed by the manufacturer and inserted into the split ring of the Shark fin device. Twenty (20) seconds exactly, a metal rod was removed to make the materials slowly absorbed. Once they hardened, fin height was measured with a caliper after separating molds and trimming the specimens. The shore D hardness was measured with a shore D hardness tester(Model HPDSD, Hans Schmidt & Co. Gmbh, Germany) in sixty (60) minutes after fabricating specimens. In each experiment, five specimens, mean and standard deviation were calculated. A one-way ANOVA test was performed at the p>0.05 level of significance. In terms of correlation among the tests, Pearson correlation coefficient was estimated. For multiple comparison, Scheffe's test was carried out. Results : A contact angle was the highest in EX with $99.23^{\circ}$ (p<0.05) while the result of the shark fin test was the longest in RE with 5.45mm. SI was the lowest (0.27mm) with statistical significance. Among the interocclusal recording materials, significant difference was observed in terms of means (p<0.05). The shore D hardness was the highest in SI with 31.0 while RE was significantly low with 16.4 (p<0.05). Among the materials, statistically significant difference was observed in terms of means when compared to the rest materials (RE), BM, RE and SI (PF and EX) and the remaining materials (BM and SI) (p<0.05). In terms of correlations among the tests, a negative correlation occurred between shore D hardness and shark fin test(r=-0.823, p=0.000). Conclusions : According to the study above, it is necessary to understand the properties of interocclusal recording materials and consider contact angle, shark fin test and properties of shore D hardness to select appropriate materials.