• Journal of the Korean Graphic Arts Communication Society
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• v.12 no.1
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• pp.13-27
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• 1994

Litho printing ink vehicles based on rosin modified phenolic are faster drying, have better durability, are harder and glosser and have greater resistance to water than ones based on ester gums. Ink-Water balance and rheological properties are important in litho printing process. These physical properties is concerned with molecular weight of Resin to use vehicle. So this paper was studied about the effects of changing molecular weight of Rosin modified phenolic on surface tension, viscosity, pseudoplasticity and printablility of Litho Inks. The results were as follows. 1) The surface tension of model inks depended on the molecular weight of the resin : Dispersion componnent of ink increase but non dispersion component decrease as molecular weight of Resin increase. 2) Water pick-up of litho ink is more fast balance, using low molecular weight of Resin. 3) Viscosity, Yield value and Newtonian value of model inks increase as molecular weight of Resin increase. 4) The litho ink prepared with the modified phenolic of which molecular weight is about 20000 showed the highest printing density and gloss.

• Journal of the Korean Graphic Arts Communication Society
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• v.12 no.1
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• pp.145-157
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• 1994

Litho printing ink vehicles based on rosin modified phenolic are faster drying, have better durability, are harder and glosser and have greater resistance to water than ones based on ester gums. Ink-Water balance and rheological properties are important in litho printing process. These physical properties is concerned with molecular weight of Resin to use vehicle. So this paper was studied about the effects of changing molecular weight of Rosin modified phenolic on surface tension, viscosity, pseudoplasticity and printability of Litho Inks. The results were as follows. 1) The surface tension of model inks depended on the molecular \veight of the resin : Dispersion componnent of ink increase but non dispersion component decrease as molecular weight of Resin increase. 2) Water pick-up of litho ink is more fast balance, using low molecular weight of Resin. 3) Viscosity, Yield value and Newtonian value of model inks increase as molecular weight of Resin increase. 4) The litho ink prepared with the modified phenolic of which molecular weight is about 20000 showed the highest printing density and gloss.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.79-82
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• 2012

The gas-solid reactor, such as rotary kiln, sintering bed, incinerator and CFB boiler, is the one of most widely used industrial reactors for contacting gases and solids. the gas-solid reactor are mainly used for drying, calcining and reducing solid materials. In the gas-solid reactor, heat is supplied to the outside of the wall or inside of the reactor. The heat transfer in gas-solid reactor encompasses all the modes of transport mechanisms, that is, conduction, convection and radiation. The chemical reactions occurring in the bed are driven by energy supplied by the heat transfer. This paper deal with the effect of heat transfer and chemical reaction in the gas-solid reactor.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.43-47
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• 2003

Coke oven is used in an iron-making process for producing coke through devolatilization of the coking coal. An unsteady 2-dimensional model of solid bed is proposed to simulate a coke oven. The model contains governing equations with partial differential equation forms for the solid phase and the gas phase. Drying and devolatilization of coking coal, heat transfer, and generation of internal pores in the coking coal are also reflected to the source terms. Simulation results show a reasonable trend compared with the physical data.

• Computers and Concrete
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• v.15 no.2
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• pp.183-198
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• 2015

Chloride ingress implies a complex interaction between physical and chemical process, in which heat, moisture and chloride ions transport through concrete cover. Meanwhile, reinforced concrete structure itself undergoes evolution due to variation in temperature, relative humidity and creep effects, which can potentially change the deformation and trigger some micro-cracks in concrete. In addition, all of these process show time-dependent performance with complex interaction between structures and environments. In the present work, a time-dependent behavior of chloride transport in reinforced concrete beam subjected to flexural load is proposed based on the well-known section fiber model. The strain state varies because of stress redistribution caused by the interaction between environment and structure, mainly dominated by thermal stresses and shrinkage stress and creep. Finally, in order to clear the influence of strain state on the chloride diffusivity, experiment test were carried out and a power function used to describe this influence is proposed.

• Nuclear Engineering and Technology
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• v.43 no.6
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• pp.489-498
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• 2011

UK National Nuclear Laboratory's (NNL's) version of the ENIGMA fuel performance code is described, including details of the development history, the system modelled, the key assumptions, the thermo-mechanical solution scheme, and the various incorporated models. The recent development of ENIGMA in the areas of whole core analysis and dry storage applications is then discussed. With respect to the former, the NEXUS code has been developed by NNL to automate whole core fuel performance modelling for an LWR core, using ENIGMA as the underlying fuel performance engine. NEXUS runs on NNL's GEMSTONE high performance computing cluster and utilises 3-D core power distribution data obtained from the output of Studsvik Scandpower's SIMULATE code. With respect to the latter, ENIGMA has been developed such that it can model the thermo-mechanical behaviour of a given LWR fuel rod during irradiation, pond cooling, drying, and dry storage - this involved: (a) incorporating an out-of-pile clad creep model for irradiated Zircaloy-4; (b) including the ability to simulate annealing out of the clad irradiation damage; (c) writing of additional post-irradiation output; (d) several other minor modifications to allow modelling of post-irradiation conditions.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.850-859
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• 2012

Devolatilization is an important mechanism in the gasification and pyrolysis of woody biomass, and has to be accordingly considered in designing a gasifier. In order to describe the devolatilization process of wood particle, there have been proposed a number of empirical correlations based on experimental data. However, the correlations are limited to apply for various reaction conditions due to the complex nature of wood devolatilization. In this study, a simple model was developed for predicting the devolatilization of a wood particle in a fluidized bed reactor. The model considered the drying, shrinkage and heat generation of intra-particle for a spherical biomass. The influence of various parameters such as size, initial moisture content, heat transfer coefficient, kinetic model and temperature, was investigated. The devolatilization time linearly increased with increasing initial moisture content and size of a wood particle, whereas decreases with reaction temperature. There is no significant change of results when the external heat transfer coefficient is over 300 $W/m^2K$, and smaller particles are more sensitive to the outer heat transfer coefficient. Predicted results from the model show a similar tendency with the experimental data from literatures within a deviation of 10%.

• Computers and Concrete
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• v.12 no.5
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• pp.669-680
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• 2013

This paper unveils a new computer based stabilization methodology for automated modeling analysis and its experimental verification for corrosion in reinforced concrete structures under the effect of varying oxygen concentration. Various corrosion cells with different concrete compositions under four different environmental conditions (air dry, submerged, 95% R.H and alternate wetting-drying) have been investigated under controlled laboratory conditions. The results of these laboratory tests were utilized with an automated computer-aided simulation model. This model based on mass and energy stabilization through the porous media for the corrosion process was coupled with modified stabilization methodology. By this coupling, it was possible to predict, maintain and transfer the influence of oxygen concentration on the corrosion rate of the reinforcement in concrete under various defined conditions satisfactorily. The variation in oxygen concentration available for corrosion reaction has been taken into account simulating the actual field conditions such as by varying concrete cover depth, relative humidity, water-cement ratio etc. The modeling task has been incorporated by the use of a computer based durability model as a finite element computational approach for stabilizing the effect of oxygen on corrosion of reinforced concrete structures.

• Computers and Concrete
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• v.12 no.6
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• pp.739-754
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• 2013

Creep and shrinkage have pronounced effects on the long-term deflection of prestressed concrete members. Under repeated loading, the rate of creep in prestressed concrete members is often accelerated. In this paper, an iterative computational procedure based on the well known Model B3 for creep and shrinkage was developed to predict the time-dependent deflection of partially prestressed concrete members. The developed model was validated using the experimental observed deflection behavior of a simply supported partially prestressed concrete beam under repeated loading. The validated model was then employed to make predictions of the long-term deflection of the prestressed beams under a variety of conditions (e.g., water cement ratio, relatively humidity and time at drying). The simulation results demonstrate that ignoring creep and shrinkage could lead to significant underestimation of the long-term deflection of a prestressed concrete member. The model will prove useful in reducing the long-term deflection of the prestressed concrete members via the optimal selection of a concrete mix and prestressing forces.

• Journal of Korea Water Resources Association
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• v.33 no.4
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• pp.483-493
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• 2000

Two dimensional finite element model, RMA, is used to simulate flood inundation phenomena from main channel to floodplain. The marsh porosity method allows finite elements to simulate gradual transition between wet and dry states. The model is applied to prismatic trapezoidal channel to test the applicability of wetting and drying. The floodwave in a river which meanders through a floodplain is also analyzed. The short-circuiting effects, in which the flow leave the meandering main channel and takes a more direct route on the floodplain, are analyzed with various sinuosity factor and roughness coefficients. Finally, the model is applied to the midstream of the Keum River. Wet/dry calculation can simulate the various discharge condition with the same finite element networks.