Search | Korea Science

Bark, Jai-Hyeong
- Journal of the Computational Structural Engineering Institute of Korea
- /
- v.20 no.5
- /
- pp.671-680
- /
- 2007
The objective of this work is to reduce drag on a bluff body within a viscous flow by applying suction or injection of fluid along the surface of the body. In addition to minimizing drag, the optimal solution tends to reduce boundary layer separation and flow recirculation. When discretized by finite elements, the optimal control problem can be posed as a large-scale nonlinearly-constrained optimization problem. The constraints correspond to the discretized form of the Navier-Stokes equations. Unfortunately, solving such large-scale problems directly is essentially intractable. We developed several Sequential Quadratic Programming methods that are tailored to the structure of the control problem. Example problems of laminar flow around an infinite cylinder in two dimensions are solved to demonstrate the methodology. We use these optimal control techniques to study the influence of number of suction/injection holes and location of holes on the resulting optimized flow. We compare the proposed SQP methods against one another, as well as against available methods from the literature, from the point of view of efficiency and robustness. The most efficient of the proposed methods is two orders of magnitude faster than existing methods.
PDF KSCI

Park, Jun Kyu;Kim, Soo Il;Kim, Dongchoul
- Transactions of the Korean Society of Mechanical Engineers B
- /
- v.38 no.7
- /
- pp.589-594
- /
- 2014
Recently, higher capacity and energy density of lithium ion batteries are increasingly demanded for enhancing their performance in view of the rise in the commercial distribution of electric and hybrid vehicles. Computational analysis of a porous structure of vanadium pentoxide cathode was performed, employing a phase field model. The incipient model was designed as a spherical structure with cylindrical-shaped pores. Modifying the diameters and lengths of the pore cylinder and the number of pores, we considered different conditions for the porous vanadium pentoxide cathodes for analyzing their effect on the amount of lithium ion intercalated to them. Subsequently, we optimized the porous structure to contain the largest amount of intercalated lithium ion during discharge.
https://doi.org/10.3795/KSME-B.2014.38.7.589 인용 PDF KSCI

Kim, Hyoung-Soo;Park, Seung-Rim;Kang, Joon-Soon;Lee, Woo-Hyeong;Kim, Ki-Wook
- Journal of the Korean Arthroscopy Society
- /
- v.5 no.1
- /
- pp.41-44
- /
- 2001
The muscular button holing of vastus medialis is a very rare case of irreducible knee dislocations, and rapid reduction of this can diminish the complications which delayed reduction accompanies. We diagnosed a patient who appeared posterolateral dislocation of the knee and protrusion of the medial femoral condyle with MRI grossly. That was reduced by open arthrotomy, followed the reconstruction of both cruciate ligaments and repair of medial collateral ligament. Patient didn't show joint instability except minor posterior sagging and had full range of motion postoperatively after 10 months.
PDF

김재오
- Journal of the Korean Society of Fisheries and Ocean Technology
- /
- v.32 no.4
- /
- pp.381-385
- /
- 1996
This paper described to experiment and analyze for the characteristic of underwater airbubble curtain which was generated by the air - bubble curtain generating unit consisted with air compressor (290l/min x 1.5Kw) and air tank(10kgf/$cm^2$) in order to provide foundation source for guiding fish schools. To layout the air - bubble curtain was made vinyl hoses( $cm^2$ emitting air - pressure, the wider hole interval of hose drilled the higher air - bubble curtain could be formed, and then the horizontal length of air - bubble curtain could be prolonged 45% according to be inclined vertical angle of air - bubble generating hose.
PDF