Youngsoo Ha

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In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: Abstract This paper is devoted to comparing numerical schemes for a differential(More)
Computational fluid dynamics simulations using the WENO-LF method are applied to high Mach number nonrelativistic astrophysical jets, including the effects of radiative cooling. Our numerical methods have allowed us to simulate astrophysical jets at much higher Mach numbers than have been attained (Mach 20) in the literature. Our simulations of the HH 1-2(More)
High Mach number astrophysical jets are simulated using a positive scheme, and are compared with WENO-LF simulations. A version of the positive scheme has allowed us to simulate astrophysical jets with radiative cooling up to Mach number 270 with respect to the heavy jet gas, a factor of two times higher than the maximum Mach number attained with the WENO(More)
OBJECTIVE Despite rapid evolution of shunt devices, the complication rates remain high. The most common causes are turning from obstruction, infection, and overdrainage into mainly underdrainage. We investigated the incidence of complications in a consecutive series of hydrocephalic patients. METHODS From January 2002 to December 2009, 111 patients(More)
We develop a theoretical tool to examine the properties of numerical schemes for advection equations. To magnify the defects of a scheme we consider a convection-reaction equation u t þ ðjuj q =qÞ x ¼ u; u; x 2 R; t 2 R þ ; q > 1: It is shown that, if a numerical scheme for the advection part is performed with a splitting method, the intrinsic properties of(More)
PURPOSE The optimal management of geometrically complex aneurysms remains challenging. The aim of this retrospective study was to evaluate the safety and feasibility of branch-selective technique (BT) in wide-necked aneurysms with an acute angle branch incorporated into the sac. MATERIALS AND METHODS Eight consecutive patients harboring wide-necked(More)