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백금 히터가 내장된 평면형 Bi - Sb 다중접합 열전변환기의 특성
이현철,김진섭,함성호,이종현,이정희,박세일,권성원 ( H . C . Lee,J . S . Kim,S . H . Ham,J . H . Lee,J . H . Lee,S . I . Park,S . W . Kwon ) 한국센서학회 1998 센서학회지 Vol.7 No.3
A planar Bi-Sb multijunction thermal converter with high thermal sensitivity and small ac-do transfer error has been fabricated by preparing the bifilar thin film Pt-heater and the hot junctions of thin film Bi-Sb thermopile on the Si₃N₄/SiO₂/Si₃N₄-diaphragm, which functions as a thermal isolation layer, and the cold junctions on the dielectric membrane supported with the Si-substrate, which acts as a heat sink, and its ac-do transfer characteristics were investigated with the fast reversed de method. The respective thermal sensitivities of the converter with single bifilar heater were about 10.1 mV/mW and 19.8 mV/mW in the air and vacuum, and those of the converter with dual bifilar heater were about 5.1 mV/mW and 7.fi mV/mW, and about 5.3 mV/mW and 7.8 mV/mW in the air and vacuum for the inputs of inside and outside heaters, indicating that the thermal sensitivities in the vacuum, where there is rarely thermal loss caused by gas, are higher than those in the air. The ac-do voltage and current transfer difference ranges of the converter with single bifilar heater were about ±1.80 ppm and ±0.58 ppm, and those of the converter with dual bifilar heater were about ±0.63 ppm and ±0.25 ppm, and about ±0.53 ppm and ±0.27 ppm, respectively, for the inputs of inside and outside heaters, in the frequency range below 10 kHz and in the air.
낮은 신호 대 잡음비 특성을 지닌 탄성파 신호에 적합한 P파 도달시간 결정 알고리즘 연구
이경수(K.S. Lee),김진섭(J.S. Kim),이창수(C.S. Lee),윤찬훈(C.H. Yoon),최종원(J.W. Choi) 한국암반공학회 2011 터널과지하공간 Vol.21 No.5
본 연구에서는 방사성폐기물처분장에서 발생하는 탄성파와 같이 낮은 신호 대 잡음비로 인하여 P파의 식별이 어려운 신호에 적합한 P파 도달시간 결정 알고리즘에 대한 연구를 수행하였다. 사용된 알고리즘은 임계전압법 Akaike Information Criterion(AIC) Two step AIC Hinkley criterion이며 샤프심 압절법에 의하여 생성된 탄성파 신호에 white noise를 적용하여 신호 대 잡음비를 낮추었다. 실험결과 임계전압 AIC Hinkley criterion 알고리즘의 경우 배경잡음 수준이 증가함에 따라 P파 도달시간의 정확성은 감소하였으나 Two step AIC 알고리즘의 경우 1차적으로 결정된 P파의 도달시간 주변의 신호를 중심으로 특성함수와 AIC 알고리즘을 반복적으로 적용함에 따라 배경잡음 수준에 관계없이 정확한 결과를 나타냈다. This paper introduces a new P wave arrival time determination algorithm of acoustic emission (AE) suitable to identify P waves with low signal-to-noise ratio generated in rock masses around the high-level radioactive waste disposal repositories. The algorithms adopted for this paper were amplitude threshold picker Akaike Information Criterion (AIC) two step AIC and Hinkley criterion. The elastic waves were generated by Pencil Lead Break test on a granite sample then mixed with white noise to make it difficult to distinguish P wave artificially. The results obtained from amplitude threshold picker AIC and Hinkley criterion produced relatively large error due to the low signal-to-noise ratio. On the other hand two step AIC algorithm provided the correct results regardless of white noise so that the accuracy of source localization was more improved and could be satisfied with the error range.