• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.111-114
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• 2005

While the existing reinforced concrete flat plate(RC flat plate) has a lot of advantages including reduced building height, it has some weak points such as many steel bars and the brittle rupture by punching shear. Compared with the RC flat plate, the post-tensioned flat plate (PT flat plate) has not only the same merits, but it also makes longer span possible and induces slab-column connections to be failed with the ductile behavior rather than with the brittle behavior by means of post-tensioning. However, it is difficult to define the joint behavior of PT flat plate under vertical and lateral loads since there are limit experimental results. For this reason, the experimental study is undertaken to investigate the comparison of behavior of PT flat plate and RC flat plate, and how flat plate(Gravity Load Resisting System) is displaced as lateral loads, like the wind and the earthquake, are occur. The result of this experiment shows that PT flat plate is generally superior to RC flat plate in terms of controlling crack, postponing stiffness deterioration, energy dissipation, etc.

• Korean Institute of Interior Design Journal
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• v.15 no.6 s.59
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• pp.172-177
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• 2006

Most of the Korean multi-dwelling houses have less than 20 years of lifespan. Because the environmental issues such as energy consumption, limited resources, and demolition waste problems became been more and more critical, we now need to focus on long lasting and adaptable buildings. Korean wall bearing apartment buildings are constructed with site cast concrete for core, exterior, and interior together with pipes varied, so when the buildings are old and life style of the users changes, it is difficult to maintain and renovate these buildings. In this study, to resolve the problems described above, two types of Korean long life multi-dwelling housing models which represent improved durability and adaptability responding user's needs and life style changes were proposed with various methods as follows: Either column and beam structure or flat slab structure was used to utilize space better. To make maintenance easier and renovation economical for both public space and each unit, plumbing pipes, ducts, and conduits were clustered at the cores and public corridors with access doors and light weight partitions with steel studs and raised floors or above-ceiling spaces were used in lieu of site cast concrete walls and floor slabs with varied pipes.

• Resources Recycling
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• v.6 no.1
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• pp.40-46
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• 1997

Sludgc d~sposal has been a major challenge in the wastewater treatment. Drying is operation which is separated fromsewage sludge to solid and liquid by heating. Drying needs to pretreatment process for effective "thation, incinerationand dispaal The objective of this work was to the drying dewatered sewage sludge by microwave heating, and tocompare the experimental rcsults with thcorctical rcsults. Microwave drylng is fast and has a high efficiency. In thepresent \ark, an unsteady state analysis of one dunensional drying, with microwave heating, is carried out. In drying ratecurve, moisture movement at falling rate period occured by dfision. A good agreement was abtamed between the modcland the experimental results using the slab sample of 0.2cm thickness. 0.2cm thickness.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.137-137
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• 2000

The surface collective modes of thin K films deposited on Al(111) have been investigated using frequency dependent photoyield measurements and momentum resolved inelastic electron scattering. Jellium based theoretical calculations have predicted a richer set of features in the thin films than for the surface of a semi-infinite solid because there are th interference between two interfaces (substrate-film and film-vacuum) and heavy damping on the substrate. The use of an optical probe and electron scattering has allowed us to draw a more complete picture of the dynamic screening in thin films. The number, dispersion, damping and optical activity of the collective modes of the thin films have been measured as a function of K film thickness. New overlayer-induced excitations are observed : At qII=0, they correspond to the antisymmetric slab mode and the multipole surface plasmon. At finite qII=0, these modes undergo a transition towards the K multipole and monopole surface plasmons. With increasing coverage, the overlayer excitations turn into the collective modes of semi-infinite K. For a consistent interpretation of photoyield and electron energy loss spectra it is crucial to account for the non-analytic dispersion of the overlayer modes at small parallel wave vectors and for the finite angular resolution of the detector. The observed dispersions confirm predictions based on the time-dependent density functional approach.

• Journal of the Geological Society of Korea
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• v.54 no.6
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• pp.683-694
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• 2018

Subduction has been the focal point of numerical studies for decades because it plays an important role in the Earth's mass and energy circulations and generates earthquakes and arc volcanoes which are closely related to the human lives. Among the studies on subduction, numerical modeling has been broadly applied to the quantitative studies on the subducting slab in the mantle which cannot be directly observed. In this study, we benchmark the numerical subduction modeling using a finite element package, COMSOL $Multiphysics^{(R)}$ and the results are consistent with the previously reported benchmark results.

• Steel and Composite Structures
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• v.33 no.2
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• pp.209-224
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• 2019

This paper describes a study of the mapping relationship between the vertical deformation of bridge structures and rail deformation of high-speed railway, taking the interlayer interactions of the bridge subgrade CRTS II ballastless slab track system (HSRBST) into account. The differential equations and natural boundary conditions of the mapping relationship between the vertical deformation of bridge structures and rail deformation were deduced according to the principle of stationary potential energy. Then an analytical model for such relationship was proposed. Both the analytical method proposed in this paper and the finite element numerical method were used to calculate the rail deformations under three typical deformations of bridge structures and the evolution of rail geometry under these circumstances was analyzed. It was shown that numerical and analytical calculation results are well agreed with each other, demonstrating the effectiveness of the analytical model proposed in this paper. The mapping coefficient between bridge structure deformation and rail deformation showed a nonlinear increase with increasing amplitude of the bridge structure deformation. The rail deformation showed an obvious "following feature"; with the increase of bridge span and fastener stiffness, the curve of rail deformation became gentler, the track irregularity wavelength became longer, and the performance of the rail at following the bridge structure deformation was stronger.

• Computers and Concrete
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• v.27 no.2
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• pp.153-162
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• 2021

This paper aims to simulate the isotropic elastic damage theory of Liu Jun (2012) using the self-programmed UMAT subroutine in the interface of ABAQUS. Liu Jun (2012)'s method based on the mechanic theory can not be used interactively with the currently commonly used finite element software ABAQUS. The advantage of this method in the paper is that it can interact with ABAQUS and provide a constitutive program framework that can be modified according to user need. The model retains the two scalar damage variables and the corresponding two energy dissipation mechanisms and damage criteria for considering the tensile and compressive asymmetry of concrete. Taking C45 concrete as an example, the relevant damage evolution parameters of its tensile and compressive constitutive model are given. The study demonstrates that the uniaxial tensile stress calculated by the subroutine is almost the same as the Chinese Concrete Design Specification (GB50010) before the peak stress, but ends soon after the peak stress. The stress-strain curve of uniaxial compression calculated by the subroutine is in good agreement with the peak stress in Chinese Concrete Design Specification (GB50010), but there is a certain deviation in the descending stage. In addition, this paper uses the newly compiled subroutine to simulate the shear bearing capacity of the shear key in a new structural system, namely the open-web sandwich slab. The results show that the damage constitutive subroutine has certain reliability.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1391-1402
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• 2021

The aim of this work is to prepare a neutron noise calculator based on the second order of average current nodal expansion method (ACNEM). Generally, nodal methods have the ability to fulfill the neutronic analysis with adequate precision using coarse meshes as large as a fuel assembly size. But, for the zeroth order of ACNEM, the accuracy of neutronic simulations may not be sufficient when coarse meshes are employed in the reactor core modeling. In this work, the capability of second order ACNEM is extended for solving the neutron diffusion equation in the frequency domain using coarse meshes. For this purpose, two problems are modeled and checked including a slab reactor and 2D BIBLIS PWR. For validating of results, a semi-analytical solution is utilized for 1D test case, and for 2D problem, the results of both forward and adjoint neutron noise calculations are exploited. Numerical results indicate that by increasing the order of method, the errors of frequency dependent coarse mesh solutions are considerably decreased in comparison to the reference. Accordingly, the accuracy of second order ACNEM can be acceptable for the neutron noise calculations by using coarse meshes in the nuclear reactor core.

• Computers and Concrete
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• v.29 no.2
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• pp.69-79
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• 2022

For long underground box utility tunnels, post-tensioned precast concrete is often used. Between precast tunnel segments, sealed waterproof flexible joints are often specified. Fault displacement can lead to excessive deformation of the joints, which can lead to reduction in waterproofing due to diminished contact pressure between the sealant strip and the tunnel segment. This paper authenticates utilization of a finite element model for a prefabricated tunnel fault-crossing founded on ABAQUS software. In addition, material parameter selection, contact setting and boundary condition are reviewed. Analyzed under normal fault action are: the influence of fault displacement; buried depth; soil friction coefficient, and angle of crossing at the fault plane. In addition, distribution characteristics of the utility tunnel structure for vertical and longitudinal/horizontal relative displacement at segmented interface for the top and bottom slab are analyzed. It is found that the effect of increase in fault displacement on the splice joint deformation is significant, whereas the effects of changes in burial depth, pipe-soil friction coefficient and fault-crossing angle on the overall tunnel and joint deformations were not so significant.

• Advances in concrete construction
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• v.13 no.2
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• pp.153-162
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• 2022

Prefabricated exterior wall panel is the main non-load-bearing component of assembly building, which affects the comprehensive performance of thermal insulation and durability of the building. It is of great significance to develop new prefabricated exterior wall panel with durable and lightweight characteristics for the development of energy-saving and assembly building. In the prefabricated sandwich insulation hanging wall panel, the selection of material for the outer layer and the arrangement of the connector of the inner and outer wall layers affect the mechanical performance and durability of the wall panels. In this paper, high performance cement-based composites (HPFRC) are used in the outer layer of the new type wall panel. FRP bars are used as the interface connector. Through experiments and analysis, the influence of the arrangement of connectors on the mechanical behaviors of thin-walled composite wall panel and the panel with window openings under two working conditions are investigated. The failure modes and the role of connectors of thin-walled composite wallboard are analyzed. The influence of the thickness of the wall layer and their combination on the strain growth of the control section, the initial crack resistance, the ultimate bearing capacity and the deformation of the wall panels are analyzed. The research work provides a technical reference for the engineering design of the light-weight thin-walled and durable composite sandwich wall panel.