• Title/Summary/Keyword: upper solutions

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ASYMPTOTIC STABILITY OF COMPETING SPECIES

  • Kim, June Gi
    • Korean Journal of Mathematics
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    • v.4 no.1
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    • pp.39-43
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    • 1996
  • Large-time asymptotic behavior of the solutions of interacting population reaction-diffusion systems are considered. Polynomial stability was proved.

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COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF THERMAL STRATIFICATION IN THE UPPER PLENUM OF THE MONJU FAST BREEDER REACTOR (몬주 고속증식로 상부플레넘에서의 열성층에 관한 전산유체역학 해석)

  • Choi, S.K.;Lee, T.H.
    • Journal of computational fluids engineering
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    • v.17 no.4
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    • pp.41-48
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    • 2012
  • A numerical analysis of thermal stratification in the upper plenum of the MONJU fast breeder reactor was performed. Calculations were performed for a 1/6 simplified model of the MONJU reactor using the commercial code, CFX-13. To better resolve the geometrically complex upper core structure of the MONJU reactor, the porous media approach was adopted for the simulation. First, a steady state solution was obtained and the transient solutions were then obtained for the turbine trip test conducted in December 1995. The time dependent inlet conditions for the mass flow rate and temperature were provided by JAEA. Good agreement with the experimental data was observed for steady state solution. The numerical solution of the transient analysis shows the formation of thermal stratification within the upper plenum of the reactor vessel during the turbine trip test. The temporal variations of temperature were predicted accurately by the present method in the initial rapid coastdown period (~300 seconds). However, transient numerical solutions show a faster thermal mixing than that observed in the experiment after the initial coastdown period. A nearly homogenization of the temperature field in the upper plenum is predicted after about 900 seconds, which is a much shorter-term thermal stratification than the experimental data indicates. This discrepancy is due to the shortcoming of the turbulence models available in the CFX-13 code for a natural convection flow with thermal stratification.

Bearing Capacity Factor of Shallow Foundation in Undrnined Clay Using the Diagrammatic Upper and Lower Bound Methods (도식적 상.하계법을 이용한 비배수 점토지반에서 얕은 기초의 지지력계수)

  • Lee, Yong-Joo
    • Journal of the Korean Geotechnical Society
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    • v.27 no.5
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    • pp.45-59
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    • 2011
  • This study introduces the diagrammatic Upper and Lower Bound (UB and LB) methods theoretically in order to derive the bearing capacity factor, $N_c$ in undrained clay and to compare with Prandtl's exact solution (1921). As a result of the theoretical study, an exact solution comes out when the UB and LB solutions are the same. In addition, the finite element analyses show that the failure loads approach to the bearing capacity factor of 5.14. Results of the FEA significantly depend on the finite element type, a number of elements, and a number of increments. From this study the exact solution defines that solutions from UB and LB are the same. However, this situation is very difficult to process, so we can confirm the exact solution as a range between UB and LB solutions.

Interpleural Catheter in the Management of Chronic Refractoy Upper Abdominal Pain -A case report- (늑막강내 카테터를 이용한 난치성 상복부통증의 치료경험 2예)

  • Lee, Kee-Heung;Lee, Geun-Bo;Park, Sung-Sik;Hong, Jung-Gil
    • The Korean Journal of Pain
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    • v.11 no.2
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    • pp.317-320
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    • 1998
  • Since Reiestad and Str$\ddot{o}$mskag reported interpleural installation of local anesthetic solutions as a technique for the management of postoperative pain in the patients undergoing cholecystectomy, renal surgery and breast surgery, many physician applied this technique for upper abdominal pain from various reasons such as technically simple, effective pain relief, less respiratory depression. So we tried interpleural analgesia in two patients who suffered from severe upper abdominal pain. One had upper abdominal pain due to chronic pancreatitis and the other had right upper abdominal pain after PTBD (percutaneous transhepatic bile drainage) for biliary cirrhosis and systemic jaundice. Both were injected 10 ml of 1% lidocaine and infused continuously with 1% lidocaine (2 ml/hr) using 2-Day Baxter$^{(R)}$ infusor. After bolus injection of lidocaine, pain scores (VAS 0~100) were recorded below 25mm and had not exceed that level during continuous infusion. After removing the catheters, two patients were all satisfied with this therapy. Our experiences with this technique showed that continuous infusion of local anesthetics through an interpleural catheter is effective in the control of refractory upper abdominal pain without any complication.

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QUASILINEARIZATION FOR SECOND ORDER SINGULAR BOUNDARY VALUE PROBLEMS WITH SOLUTIONS IN WEIGHTED SPACES

  • Devi, J.Vasundhara;Vatsala, A.S.
    • Journal of the Korean Mathematical Society
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    • v.37 no.5
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    • pp.823-833
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    • 2000
  • In this paper, we develop the method of quasilinearization comvined with the methos of upper and lower solutions for singular second order boundary value problems in weighted spaces. The sequences constructed converge uniformly and monotonically to the unique of the second singular order boundary value problem. Further we prove the rate of convergence is quadratic.

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FIXED POINTS AND VARIATIONAL PRINCIPLE WITH APPLICATIONS TO EQUILIBRIUM PROBLEMS ON CONE METRIC SPACES

  • Bae, Jong-Sook;Cho, Seong-Hoon
    • Journal of the Korean Mathematical Society
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    • v.50 no.1
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    • pp.95-109
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    • 2013
  • The aim of this paper is to establish variational principle on cone metric spaces and to give some existence theorems of solutions for equilibrium problems on cone metric spaces. We give some equivalences of an existence theorem of solutions for equilibrium problems on cone metric spaces.

Fluid flow in a Two-layer porous medium (다공질매체내의 류체류동)

  • 이충구;조성환
    • Journal of the KSME
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    • v.16 no.1
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    • pp.49-53
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    • 1976
  • Groundwater flow in a two-layer aquifer is studied theoretically and experimentally. Nonlinear differential equations are independently linearized for the upper and the lower layer, and approximate solutions are obtained. Fine sands and coarse sands are used in experiments. For steady flow, theoretical solutions agrees excellently with experimental results For unsteady flow, however, agreement is not so good, because the experimental conditions do not match with theoretical assumptions.

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Existence and Uniqueness of Solutions of Fractional Differential Equations with Deviating Arguments under Integral Boundary Conditions

  • Dhaigude, Dnyanoba;Rizqan, Bakr
    • Kyungpook Mathematical Journal
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    • v.59 no.1
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    • pp.191-202
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    • 2019
  • The aim of this paper is to develop a monotone iterative technique by introducing upper and lower solutions to Riemann-Liouville fractional differential equations with deviating arguments and integral boundary conditions. As an application of this technique, existence and uniqueness results are obtained.