Central venous catheter (CVC) related thrombosis is a major cause of CVC dysfunction in patients under hemodialysis. The aim of our study was to investigate the impact of CVC insertion on hemodynamics in the central veins and to examine the changes in hemodynamic environments that may be related to thrombus formation due to the implantation of CVC. Patient-specific models of the central veins with and without CVC were reconstructed based on computed tomography images. Flow patterns in the veins were numerically simulated to obtain hemodynamic parameters such as time-averaged wall shear stress (TAWSS), oscillating shear index (OSI), relative residence time (RRT), and normalized transverse wall shear stress (transWSS) under pulsatile flow. The non-Newtonian effects of blood flow were also analyzed using the Casson model. The insertion of CVC caused significant changes in the hemodynamic environment in the central veins. A greater disturbance and increase of velocity were observed in the central veins after the insertion of CVC. As a result, TAWSS and transWSS were markedly increased, but most parts of OSI and RRT decreased. Newtonian assumption of blood flow would overestimate the increase in TAWSS after CVC insertion. High wall shear stress (WSS) and flow disturbance, especially the multidirectionality of the flow, induced by the CVC may be a key factor in initiating thrombosis after CVC insertion. Accordingly, approaches to decrease the flow disturbance during CVC insertion may help restrain the occurrence of thrombosis. More case studies with pre-operative and postoperative modeling and clinical follow-up need to be performed to verify these findings. Non-Newtonian blood flow assumption is recommended in computational fluid dynamics (CFD) simulations of veins with CVCs.

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Purpose: This study aimed to investigate the characteristics of male taekwondo players by evaluating their heart rate, oxygen intake, and cardiorespiratory function according to the growth period. Methods: This study enrolled 34 male middle school, high school, and university taekwondo players belonging to D city. Their heart rate, oxygen intake, and cardiorespiratory function were evaluated according to the growth period. Results: The resting heart rate was significantly different between the groups, and the values in high school athletes were lower than those in middle school athletes and university athletes. A significant difference was found between the groups in the maximum oxygen intake, with values higher in high school athletes than in middle school athletes and university athletes. The respiratory rate at the anaerobic threshold was significantly different between the groups, with values higher in middle school players than in high school players. Conclusion: This study revealed significant differences among the groups, and results will guide in creating a systematic training program for growing taekwondo players.

Basic precondition for effective curriculum on learning activities to take place, the internal and external environment of the school facilities, improve the environment of the classroom space and etc.Specifically, the use of classroom space, hardly learners improve their academic motivation to achievement tend to concentrate within the party regularly scheduled class hours. Physical environment surrounding them is giving considerable impact for behavioral psychological and bodily change of the learners.In this study, we are focused on the form of the learner in the general classroom space and classroom environment that can increase the learning effect will be examined. Consequently, What is appropriate classroom environment for learning increase the concentration of elements are presented.. 키워드：대학강의실, 좌석이용형태, 행동심리, 학업성취도, 선호도