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정시영,정구영,어은경,노현기 대한응급의학회 2009 大韓應急醫學會誌 Vol.20 No.5
Purpose: The aim of this study was to examine the diagnostic accuracy and effectiveness of transvaginal ultrasonography (TVUS) performed by emergency physicians (EPs’) in the emergency department. Methods: In this study, female patients with lower abdominal pain who had risks for obstetric and gynecologic diseases were assessed. The accuracy and effectiveness of TVUS performed by emergency physicians was determined by comparing EPs’ interpretations of TVUS with the interpretations of TVUS by OGs CT findings, and surgical pathologic results. Results: Forty-one patients were included in the study. The diagnosis was changed in 48.8% of the patients after the TVUS had been performed by an EPs’. When the accuracy of diagnosis was compared pre- and post-TVUS, the accuracy of post-TVUS (80.5%) was higher than the pre-TVUS (39.0%). The agreement between the sonographic findings of EPs’ and OGs’ was substantial (accuracy=81.3~93.8%; κ=0.611~0.811; p<0.05). The accuracy of TVUS performed by EPs’ in obstetric and gynecologic diseases was 90.6%. The sensitivity and specificity were 100% and 90.9%, respectively, and the positive and negative predictive values were 96.8% and 100%, respectively. Conclusion: TVUS performed by EPs’ is of considerable help in establishing the correct diagnosis with a high degree of accuracy.
Electro-Rheological 유체를 이용한 무한폭 스퀴즈 필름 댐퍼 해석
정시영,최승복,조용철,Jeong, Si-Yeong,Choe, Seung-Bok,Jo, Yong-Cheol 한국정밀공학회 1992 한국정밀공학회지 Vol. No.
This paper addresses on the determination of damping coefficients of an infinitely long squeeze film damper operating with an electro-rheological (ER) fluid. The ER fluid behaves as Bingham fluid with an electric field dependent yield shear stress. AS phenomenological model of the fluid is adopted for the relationship between the yield shear and the intensity of the electric field imposed on the fluid domain. The model is then incorporated with the governing equation and associated boundary conditions of the squeeze film damper executing a circula centered orbit for the expression of dimension- less damping coefficients. Numerical simulation is performed to evaluate the performance improvement of the proposed squeeze film damper.
정시영,조광운 대한설비공학회 1998 설비공학 논문집 Vol.10 No.6
The present study has been directed at developing thermal models to investigate the dynamic behavior of a solar cooling system including an absorption chiller, solar collectors, a hot water storage tank, a fan coil unit, and the air-conditioned space. The operation of the system was simulated for 8 hours in two different operation modes. In the mode 1, the system operated without any capacity control.0 the mode 2, an auxiliary boiler supplied heat to the generator if hot water temperature became lower than a certain value. Moreover, the mass flow rate of hot water to the generator was controlled by comparing the instantaneous room air temperature with the design value. The variation of temperature and concentration in the system components and that of heat transfer rates in the system were obtained for both modes of operation. It was found that the room temperature was maintained near the desired value in the mode 2 by supplying auxiliary heat or controlling the mass flow rate of hot water, while the deviation of room temperature was quite great in the mode 2.