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Yini Chen,Changping Li,Shuang Li,Moran Xu,Lei Huang,Shujian Li,Pengnan Li,Xinyi Qiu,Tae Jo Ko 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.3
Electric discharge machining (EDM) is used widely in machining titanium alloys, but the modified layer formed can weaken the mechanical properties of the parts. The present study examined the formation of craters and the evolution of the modified layer (melting layer + heat-affected layer) in RC-type EDM using a fluid–solid coupled temperature field model. This model adopts the level set method to track the liquid–solid two-phase and the driving force equation to control the recoil pressure. The results showed that the discharge energy has a significant effect on the formation of the modified layer. The formation of the modified layer showed phased characteristics with time. The variation law and formation mechanism of the modified layer are described in detail. A verification experiment showed that the diameter and depth of the crater were in good agreement with the simulation results. These results can provide an important reference for EDM to formulate the machining parameters.
Xueyi Zheng,Yini Huang,Yubo Liu,Yun Wang,Rushuang Mao,Fei Li,Longhui Cao,Jianhua Zhou 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.2
Objective: To determine the added value of a shear-wave elastography (SWE) quality map (QM) in the diagnosis of breast lesions and in predicting the biological characteristics of invasive breast cancer. Materials and Methods: Between January 2016 and February 2019, this study included 368 women with 368 pathologically proven breast lesions, which appeared as poor-quality regions in the QM of SWE. To measure shear-wave velocity (SWV), seven regions of interest were placed in each lesion with and without QM guidance. Under QM guidance, poor-quality areas were avoided. Diagnostic performance was calculated for mean SWV (SWVmean), max SWV (SWVmax), and standard deviation (SD) with QM guidance (SWVmean + QM, SWVmax + QM, and SD + QM, respectively) and without QM guidance (SWVmean - QM, SWVmax - QM, and SD - QM, respectively). For invasive cancers, the relationship between SWV findings and biological characteristics was investigated with and without QM guidance. Results: Of the 368 women (mean age, 47 years; SD, 10.8 years) enrolled, 159 had benign breast lesions and 209 had malignant breast lesions. SWVmean + QM (3.6 ± 1.39 m/s) and SD + QM (1.02 ± 0.84) were significantly different from SWVmean - QM (3.29 ± 1.22 m/s) and SD - QM (1.46 ± 1.06), respectively (all p < 0.001). For differential diagnosis of breast lesions, the sensitivity and areas under the receiver operating characteristic curve (AUC) of SWVmean + QM (sensitivity: 89%; AUC: 0.932) were better than those of SWVmean - QM (sensitivity, 84.2%; AUC, 0.912) (all p < 0.05). There was no significant difference in sensitivity and specificity between SD + QM and SD - QM (all p = 1.000). Among the biological characteristics of invasive cancers, lymphovascular involvement, axillary lymph node metastasis, negative estrogen receptor status, negative progesterone receptor status, positive human epidermal growth factor receptor status, and aggressive molecular subtypes showed higher SWVmean + QM (all p < 0.05), while only lymphovascular involvement showed higher SWVmean - QM (p = 0.036). Conclusion: The use of QM in SWE might improve the diagnostic performance for breast lesions and facilitate prediction of the biological characteristics of invasive breast cancers.