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Uddanapalli Sreeramulu Srinivasan,Natarajan Raghunathan,Lawrence Radhi 대한척추외과학회 2014 Asian Spine Journal Vol.8 No.4
Study Design: It is a case series involving clinical presentation, radiological findings, surgical technique and long term outcome of Non-dysraphic intramedullary spinal cord lipomas in adults along with the review of the literature. Purpose: The purpose of the study is to find out from our series as well as from literature what determines the long term outcome and how it can be improved in patients diagnosed to have intramedullary spinal cord lipomas. Overview of Literature: Non-dysraphic spinal intramedullary lipomas in adults are extremely rare. Majority of cases occur in children and in cervico-dorsal regions. Only eight cases of dorso-lumbar spinal lipomas without spinal dysraphism in adults have been reported in the English literature till 2013. Methods: Here we report our experience with three such cases in the dorsolumbar region and discuss the surgical technique and the long term outcome of such cases. Results: Review of literature and from our own cases we conclude that long term outcome after surgery is determined by the preoperative neurological status. Conclusions: Earlier surgical intervention with preserved neurological status results in better outcome. Radical subtotal excision without producing iatrogenic postoperative neurological deficit should be the goal of the surgery and it stabilizes the disease process in the long run. When early clinico-radiological signs of recurrence develop, such patient’s to be reoperated immediately to prevent them from developing a fixed neurological deficit.
Analysis of the 3D Zone of Flow Establishment from a Ship's Propeller
Wei-Haur Lam,Gerard Hamill,Desmond Robinson,Srinivasan Raghunathan,Yongchen Song 대한토목학회 2012 KSCE Journal of Civil Engineering Vol.16 No.4
In the present study an experimental investigation of the time-averaged velocity and turbulence intensity distributions from a ship’s propeller, in “bollard pull” condition (zero speed of advance), is reported. Previous studies have focused mainly on the velocity profile of not a rotating ship propeller but a plain jet. The velocity profile of a propeller is investigated experimentally in this study. The velocity measurements were performed in laboratory by using a Laser Doppler Anemometry (LDA). The measurements demonstrated two-peaked ridges velocity profile with a low velocity core at the centre within the near wake. The two-peaked ridges combined to be one-peaked ridge at 3.68 diameters downstream indicating the end of the zone of flow establishment. The study provides useful information from a rotating ship’s propeller rather than a simplified plain jet to researchers investigating flow velocity generated from a propeller and probably resulting local scouring.
이영기(Young-Ki Lee),김희동(Heuy-Dong Kim),Srinivasan Raghunathan 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
Flight bodies are subject to highly unstable and severe flow conditions during taking-off and landing<br/> periods. In this situation, the flight bodies essentially experience accelerating or decelerating flows, and the<br/> aerodynamic characteristics can be completely different from those of steady flows. In the present study,<br/> unsteady aerodynamic characteristics of an aerofoil accelerating at subsonic speeds are investigated using a<br/> computational method. Two-dimensional, unsteady, compressible Navier-Stokes simulations are conducted<br/> with a one-equation turbulence model, Spalart-Allmaras, and a fully implicit finite volume scheme. An<br/> acceleration factor is defined to specify the unsteady aerodynamics of the aerofoil. The results show that the<br/> acceleration of the subsonic aerofoil generally leads to a variation in aerodynamic characteristics and it is<br/> more significant at angles of attack.
A Computational Study of a Supersonic Flow with Base Bleed
Young-Ki Lee(이영기),Heuy-Dong Kim(김희동),Srinivasan Raghunathan 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
A numerical analysis has been performed to give an understanding of the physics of a compressible base flow with mass bleed in a Mach 2.47 freestream. Axisymmetric, compressible mass-averaged Navier-Stokes equations are computed using a two-equation turbulence model, standard k-ω, and a fully implicit finite volume scheme. The mass bleed is characterized by the change in the mass flow rate of the bleed jet nondimensionalized by the product of the base area and freestream mass flux. The result showing that there is an optimum bleed condition with maximum base pressure, leading to a minimum base drag, is clearly predicted and the validation with experimental data shows reasonable agreement.