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이명석,조정연,김승협 대한초음파의학회 2010 ULTRASONOGRAPHY Vol.29 No.2
Purpose: To retrospectively evaluate the diagnostic value of ultrasonographic differentiation of small angiomyolipomas (AMLs) from renal cell carcinomas (RCCs) by measuring relative echogenicity (RE) on PACS. Materials and Methods: Thirty-six cases of < 3 cm, pathologically-proven RCCs and 42 cases of size-matched AMLs were enrolled. We measured the grayscale representing echogenicity of the mass, the renal cortex, and the sinus fat on PACS using a ROI cursor. The RE of the tumor was calculated by setting the grayscale of the renal cortex and sinus fat as 0% and 100%, respectively. We compared REs of AMLs and RCCs, including subgroups of each tumor. ROC analyses between RCCs and AMLs or non-fatty AMLs were performed for obtaining diagnostic performance (Az value) of RE measurement and for extracting sensitivities of RE with fixed specificities of 90%and 95%. Results: The RE of AMLs was higher than RCCs (p < 0.05). The RE of non-fatty AMLs was significantly lower than fatty AMLs, and higher than any subgroups of RCCs (p < 0.05). RE measurement provided good diagnostic performance (Az ≥0.840, p < 0.05) with competitive sensitivity/specificity for differentiating AMLs from RCCs regardless of AML subgroups. Conclusions: RE measurement on PACS can be helpful in the differential diagnosis of small AMLs and RCCs with the intrinsic merits of ultrasonography.
이명석,정경모,공경철,Lee, Myoungseok,Jung, Kyungmo,Kong, Kyoungchul 제어로봇시스템학회 2015 제어·로봇·시스템학회 논문지 Vol.21 No.7
DOB (Disturbance Observer) is an useful control method for estimating the disturbance applied to dynamic systems. Disturbance observer can be used to implement a robust control system to generate a control input for rejecting the disturbance, and it can be also used to estimate the disturbance to obtain information. The system that uses disturbance estimation is investigated for high performance control such as automatic door systems, walking robot and electric power steering system in vehicles. In this paper, a novel disturbance observer which is called disturbance and current observer for estimating load torque in the motor system is proposed. The difference between the DOB for disturbance rejection and DCOB is mathematically verified. Current and angular velocity are required for estimating the load torque of the motor in DOB. However, the DCOB can estimate load torque and current without current sensor. DCOB is designed based on modeling of the motor system. Appropriate Q-filter is selected and the applicability of DCOB is verified by simulation. The estimated disturbance and current of the electric motor can be verified without current sensor, as experiments of the actual motor system.