• Nuclear Engineering and Technology
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• v.16 no.2
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• pp.70-79
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• 1984

With the help of the nuclear computational system for a large LMFBR (KAERI-26 group cross section library/1DX/2DB), the reactivity coefficients for the diagrid expansion and the pad expansion at the beginning of cycle of the equilibrium core of SUPER-PHENIX I are calculated and reviewed. the core is described using R-Z geometry model, and a two-dimensional multigroup diffusion theory is used. For reference cases, reactivity calculations for radial and axial uniform expansion are performed, and also calculated are reactivity variations due to changes in material density and core volume. The reactivity coefficient for the diagrid expansion is calculated to be -0.553pcm/mil. The temperature coefficient corresponding to the above value is -1.0766pcm/$^{\circ}C$ and is well in accord with the French datum of -1.09pcm/$^{\circ}C$ within 1.2% difference. With the use of 4he calculational method for the diagrid expansion effect, reactivity calculations for the pad expansion bringing about nonuniform expansion are performed, which show that the calculational method is very useful in the analysis of the pad expansion effect. The reactivity coefficients for the pad expansion are calculated to be -0.2743 pcm/mil and -0.2786pcm1mi1 for the averaged expansion model and for the integrated pancake model, respectively. Under the assumption of the free expanding core the temperature reactivity coefficients for each model are obtained to be -0.5766pcm/$^{\circ}C$ and -0.5858pcm/$^{\circ}C$, both of which agree with the French datum of -0.574pcm/$^{\circ}C$ within 2% difference.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.213-220
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• 2015

CFT column has a lot of structural advantages due to the composite behavior between in-filled concrete and steel tube. This paper deals with the development of an effective numerical model which can consider the bond-slip behavior between both components of concrete matrix and steel tube without taking double nodes. Since the applied axial load to in-filled concrete matrix is delivered to steel tube by the confinement effect and the friction, the governing equation related to the slip behavior can be constructed on the basis of the force equilibrium and the compatability conditions. In advance, the force and displacement relations between adjacent two nodes make it possible to express the slip behavior with the concrete nodes only. This model results in significant savings in the numerical modeling of CFT columns to take into account the effect of bond-slip. Finally, correlation studies between numerical results and experimental data are conducted to verifying the efficiency of the introduced numerical model.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.129-136
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• 2011

Simulated Moving Bed(SMB) process consists of multiple chromatographic columns, which are usually partitioned into four zones. Such a process characteristic allows a continuous binary separations those are impracticable in conventional batch chromatographic processes. Compared with batch chromatography, SMB has advantages of continuity, high purity and productivity. Various researches have been reported for the integration of reaction and recovery during process operation on the purpose of economics and effectiveness. Simulated Moving Bed Reactor(SMBR) is introduced to combine SMB as a continuous separation process and reactor. Several cases of SMBR have been reported for diverse reactions with catalytic, enzymatic and chemical reaction on ion exchange resin as main streams. With an early type of fixed bed using catalyst, SMBR has been developed as SMB using fluidized enzyme, SMB with immobilized enzyme and SMB with discrete reaction region. For simple modeling and optimization of SMBR, a method considering convection only is possible. A complex method considering axial dispersion and mass transfer resistance is needed to explain the real behavior of solutes in SMBR. By combining reaction and separation, SMBR has benefits of lower installation cost by minimizing equipment use, higher purity and yield by avoiding the equilibrium restriction in case of reversible reaction.

• Journal of the Korea Concrete Institute
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• v.27 no.6
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• pp.615-623
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• 2015

The previous strut-and-tie models (STMs) to evaluate the shear strength of squat shear walls with aspect ratio less than 2.0 do not consider the axial load transfer of concrete strut and individual shear transfer contribution of horizontal and vertical shear reinforcing bars in the web. To overcome the limitation of the existing models, a simple STM was established based on the crack band theory of concrete fracture mechanics. The equivalent effective width of concrete strut having a stress relief strip was determined from the neutral axis depth and effective factor of concrete strength. The shear transfer mechanism of shear reinforcement at the extended crack band zone was calculated from an internally statically indeterminate truss system. The shear transfer capacity of concrete strut and shear reinforcement was then driven using the energy equilibrium in the stress relief strip and crack band zone. The shear strength predictions of squat shear walls evaluated from the current models are in better agreement with 150 test results than those determined from STMs proposed by Siao and Hwang et al. Furthermore, the proposed STM gives consistent agreement with the observed trend of the shear strength of shear walls against different parameters.