• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4D
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• pp.555-564
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• 2011

More than sixty percentages of the highway constructed by concrete pavements in South Korea and over half of the concrete pavements were twenty years or older. The most of South Korea road is hard to provide a bypass in conditions of network of roads. Asphalt concrete overlay has been used for the overlay of aged concrete pavement. However, the cost of maintenance and rehabilitation in an asphalt overlay is expensive by early damage. Therefore, bonded concrete overlay was recently attempted in South Korea as an alterative method of rehabilitation for aged concrete pavement. Hence, it needed to investigate the factors to find performance of the bonded concrete overlay life. However, there is no performance data of the concrete overlay in South Korea. This study was to make a database of an affecting of the pavement life and draws statistical analysis of the performance data on the LTPP (Long Term Pavement Performance) database of U.S.A.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.4
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• pp.425-433
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• 2012

Purpose: Basic design of virtual colored overlay, film overlay, colored lenses and colored glasses for people with Scotopic Sensitivity Syndrome. Methods: I calculated sRGB and RGB values of the overlays from measured data. I evaluated the relationship between the combinational chromaticities composed of Galaxy Tab white background and film overlays and the chromaticities of pure film overlays. Results: Implementable sRGB and RGB values of the overlays is calculated. The chromaticities of film overlays are different from them with white paper background and them with Galaxy Tab's white background, but showed a certain relationship between them. Light transmittances of Intuitive Overlay are the most (59%-79%) among them and average light reflectance of Reading Ruler is least(8%). Conclusions: The sRGB values and the RGB values are directly applicable to implement assistive tools and the light transmittances are used to calculate ${\alpha}$, transparency of virtual overlay in IT devices. It is recommended to consider the chromaticity of white color in implementing virtual colored overlay in the case which the chromaticity is considerably different to theoretical chromaticity of white color.

• Smart Media Journal
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• v.2 no.1
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• pp.8-16
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• 2013

The significant enhancement of the edge portion of computer networks including user-side machines and last mile network links encourages the research of the overlay network based data dissemination systems. Varieties of overlay network based data dissemination systems has distinct purposes, and each of them has a proper structure of an overlay network and a efficient communication protocol. In this paper, overlay network based data dissemination systems for Flash Dissemination, whose target is the distribution of relatively small size data to very large number of recipients within very short time, are explored. Mainly two systems, RECREW and FaReCAST, are introduced and analyzed in the aspects of design considerations for overlay networks and communication protocols. According to evaluations for flash dissemination scenarios, it is observed that the proposed overlay network based flash dissemination systems outperforms the previous overlay network based multicasting systems, in terms of the reliability and the dissemination delay. Moreover, the theoretical analysis of the reliability of data dissemination is provided by analysing FaReCAST.

• Journal of Industrial Technology
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• v.18
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• pp.363-370
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• 1998

This study focused on the development of an alternative stress estimation procedure to instantly calculate the critical stresses bonded concrete pavement. Closed form analysis is commonly used to analyze pavement structures. This type of analysis assumes linearelastic material properties and static loading conditions. The well-known ILLI-SLAB finite element program was used for the analysis. Bonded concrete overlay analyzed the stress distribution, behavior and load carrying capacity under track load is made evaluation standard of bonded concrete overlay. In the study, the following results were derived ; The properties of strength is that compress and 3-point bending strength of existing pavement is deteriorated with $184kg/cm^2$, $59kg/cm^2$ but compress and splitting tensile strength of overlay is satisfied with $465kg/cm^2$, $45kg/cm^2$. Load transfers is happen at adjacent slab by interlocking under track load. The stress distribution under interior, corner and edge load is described high loading position surrounding then loading position.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.191-196
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• 2002

The bonding strength of the interface between the actual bridge concrete deck and overlay was primarily affected by the shear that depended on the flexural behavior than pure tensile, but the field bonding test measured bonding strength by the pure tensile due to simplicity and field applicability. Therefore, the purpose this study was to evaluate the required direct bond strength for bridge deck overlay using Finite element analysis with the many variavles such as bridge deck types, span length, material properties, lanes, and loading types. The commercial program LUSAS was used in analysis. The analysis results were compared to the value of specification currently used in highway construction site.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.151-152
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• 2008

The planning and management of the watershed environment require huge amount of information regarding almost all aspects of natural and manmade features of the area. Until lately this study could be achieved through days of exhaustive surveys map generation and tedious calculations. Remote sensing and GIS provides huge temporal database for an area and GIS provides the powerful tool for spatial and non-spatial analysis of remotely sensed data. The paper highlights the assessment of land potentiality using weighed overlay analysis with drainage density, soil, slope and lineament, LULC map was used to identify the utilization area of the watershed. The arithmetic overlay analysis was performed with potential and utilization layer to assess the availability of land for the future development.

• Structural Engineering and Mechanics
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• v.65 no.5
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• pp.535-546
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• 2018

The objective of this study is to understand the behaviour of hollow core slabs strengthened with FRP and hybrid techniques through numerical and analytical studies. Different strengthening techniques considered in this study are (i) External Bonding (EB) of Carbon Fiber Reinforced Polymer (CFRP) laminates, (ii) Near Surface Mounting (NSM) of CFRP laminates, (iii) Bonded Overlay (BO) using concrete layer, and (iv) hybrid strengthening which is a combination of bonded overlay and NSM or EB. In the numerical studies, three-dimensional Finite Element (FE) models of hollow core slabs were developed considering material and geometrical nonlinearities, and a phased nonlinear analysis was carried out. The analytical calculations were carried out using Response-2000 program which is based on Modified Compression Field Theory (MCFT). Both the numerical and analytical models predicted the behaviour in agreement with experimental results. Parametric studies indicated that increase in the bonded overlay thickness increases the peak load capacity without reducing the displacement ductility. The increase in FRP strengthening ratio increased the capacity but reduced the displacement ductility. The hybrid strengthening technique was found to increase the capacity of the hollow core slabs by more than 100% without compromise in ductility when compared to their individual strengthening schemes.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.185-192
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• 2002

The performance of old and the new concrete construction depends upon bond strength between old and the new concrete. Current adhesive and strength measurement method ignores the effect of stress concentration from shape of specimens. Therefore, this research calculates stress concentration coefficient as the ratio of drilling depth to drilling diameter($h_s/D$), the ratio of overlay thickness to drilling diameter($h_0/D$), the ratio of steel disk thickness to drilling diameter(t/D), the ratio of overlay elastic modulus to substrate modulus($E_1/E_0$), the distance from core to corner border(L_$_{corner}$) and the distance between cores(L_$_{coic}$) vary. The finite element method is adapted to analysis The results from 'the F.E.M analysis are as follows. The stress concentration effects can be minimized when the ratio of drilling depth to drilling diameter($h_s/D$) is 0.20~0.25, the elastic modulus ratio($E_1/E_0$) is 06~1.0, and the ratio of steel disk thickness to drilling diameter(t/D) is 3.0. The overlay thickness, the distance from specimens to corner border(L_$_{corner}$), the distance between cores(L_$_{coic}$) almost do not affect to the stress concentration.

• International Journal of Highway Engineering
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• v.9 no.2 s.32
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• pp.63-76
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• 2007

The transformed field domain analysis method was developed in this study to investigate the aspects of the stress distribution in overlaid concrete pavement systems under multi-axle vehicle loads. The overlay was assumed to be perfectly bonded or perfectly unbonded to the existing concrete pavement. The loads considered included the dual tired single-axle, tandem-axle, and tridem-axle loads, and the effects of the overlay's thickness, elastic modulus, and Poisson's ratio on the stress distribution were investigated. Details of the analysis method in the transformed field domain to analyze the overlaid pavement was described in this paper and the analysis results were verified by comparing with those obtained using the finite element method. From the analysis, it was found that the maximum tensile stress in the existing slab decreased as the overlay's thickness, elastic modulus, and Poisson's ratio increased, and the bonded overlay showed more significant effects than the unbonded one. The overlay's Poisson's ratio did not much affect the stresses, and the features of the maximum stress reduction in the existing slab due to the increase of the thickness, elastic modulus, and Poisson's ratio of the overlay were investigated. The effects of the number of axles on the stress distribution and the maximum stress were also investigated.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.138-144
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• 2013

The automation technology for overlay welding is needed due to the occurrence of severe corrosion and abrasion on the surface of internal contact in different shape of fittings. In Korea, different shapes of fittings have been manufactured by using the imported equipment of overlay welding automation at some companies. Thus the research on the development of overlay welding automation system (in short, OWAS) for a large L-type tube is urgently needed. In this paper, the investigation is focused on the optimal design of a supporting base for the (currently developing) OWAS of large L-type tube. Specifically we assume that the base which supports the equipment during the process of overlay welding is loaded as self-weight in the direction of gravity through static analysis especially when it is rotated 180 degree on the OWAS. For optimal design of a supporting base for OWAS of large L-type tube, Solidworks(R) (for 3-dimensional modelling) and ANASYS Workbench(R) (for structural analysis) are incorporated so as to proceed an optimization routines based on Response Surface Method (RSM) and Design of Experiment (DOE). In more specific, DOE finds out major factors (or dimensions) of the supporting base by using MINITAB(R). Then the regression equations between design variables (the major factors of supporting base) and response variables (deformation, stress and safety factor for the supporting base), which will be resulted in by RSM, verify the major factors of DOE. In the next step, Central Composite Design (CCD) plans 20 simulations of ANASYS Workbench(R) and then figures out the optimal values of design variables which will be reflected on the manufacturing of supporting base. Finally welding experiment is conducted to figure out the influence of overlay welding quality in applying the optimized design values of supporting base to the actual OWAS.