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RISS 인기검색어
- 검색키워드
- 저자 : Sijin Li (검색결과 3 건)
- 무료
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Correcting the Elastic-modulus Error of Quartz Glass Using Digital Speckle-pattern Interferometry
Ziyang Song,Weixian Li,Sijin Wu,Lianxiang Yang 한국광학회 2023 Current Optics and Photonics Vol.7 No.4
Three-point bending is the main method for measuring the elastic modulus of a thin plate. Although various displacement transducers may be used to measure the bending, these are single-point measurements, and it is difficult to eliminate the error caused by eccentric load and shear force. Error-correction models for the elastic modulus of quartz glass using digital speckle interferometry are proposed for eccentric load and shear force. First, the positional misalignment between maximum deflection and load is analyzed, and the error caused by eccentric load is corrected. Then, the additional displacement caused by shear force at different positions of the quartz glass plate is explored. The effect of shear deformation is also corrected, by measuring two points. Since digital speckle interferometry has the advantage of full-field measurement, it can simultaneously obtain deflection data for multiple points to realize error correction. Experimental results are presented to demonstrate that the proposed model can effectively correct the measurement error of the elastic modulus.
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Junction temperature measurement method for IGBTs using turn-on miller plateau duration
Guo, Chunsheng,Zhang, Shiwei,Wei, Lei,Li, Hao,Wang, Sijin,Zhu, Konggang The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.9
A new method is proposed for the measurement of the junction temperature of insulated gate bipolar transistors (IGBTs) during operation. The application of this method overcomes the problems arising from the complexity of measurement circuits or the difficulty of tests. The proposed measurement method uses the turn-on Miller plateau duration (t<sub>mon</sub>), i.e., the duration from the first rising edge to the second rising edge of the gate-emitter voltage, of an IGBT. The obtained results show that t<sub>mon</sub> is strongly linear with respect to temperature. For comparison, the temperature-sensitive electrical parameters (TSEPs) turn-off Miller plateau duration (i.e., the duration between the two falling edges of the V<sub>ge-off</sub> curve) were also measured. The obtained results show that t<sub>mon</sub> exhibits a high sensitivity that permits accurate determination of the junction temperatures of IGBTs.
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Rui Yan,Jianbo Song,Zhifang Wu,Min Guo,Jianzhong Liu,Jianguo Li,Xinzhong Hao,Sijin Li 대한영상의학회 2015 Korean Journal of Radiology Vol.16 No.4
To determine the efficacy of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in the detection of radiation-induced myocardial damage in beagles by comparing two pre-scan preparation protocols as well as to determine the correlation between abnormal myocardial FDG uptake and pathological findings. The anterior myocardium of 12 beagles received radiotherapy locally with a single X-ray dose of 20 Gy. 18F-FDG cardiac PET/CT was performed at baseline and 3 months after radiation. Twelve beagles underwent two protocols before PET/CT: 12 hours of fasting (12H-F), 12H-F followed by a high-fat diet (F-HFD). Regions of interest were drawn on the irradiation and the non-irradiation fields to obtain their maximal standardized uptake values (SUVmax). Then the ratio of the SUV of the irradiation to the non-irradiation fields (INR) was computed. Histopathological changes were identified by light and electron microscopy. Using the 12H-F protocol, the average INRs were 1.18 ± 0.10 and 1.41 ± 0.18 before and after irradiation, respectively (p = 0.021). Using the F-HFD protocol, the average INRs were 0.99 ± 0.15 and 2.54 ± 0.43, respectively (p < 0.001). High FDG uptake in irradiation field was detected in 33.3% (4/12) of 12H-F protocol and 83.3% (10/12) of F-HFD protocol in visual analysis, respectively (p = 0.031). The pathology of the irradiated myocardium showed obvious perivascular fibrosis and changes in mitochondrial vacuoles. High FDG uptake in an irradiated field may be related with radiation-induced myocardial damage resulting from microvascular damage and mitochondrial injury. An F-HFD preparation protocol used before obtaining PET/CT can improve the sensitivity of the detection of cardiotoxicity associated with radiotherapy.
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