• Preventive Nutrition and Food Science
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• v.13 no.4
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• pp.348-353
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• 2008

Aerobic bacterial growth on Korean pan.fried meat patties as a primary quality deterioration factor was modeled as a function of temperature to estimate microbial spoilage on a real.time basis under dynamic storage conditions. Bacteria counts in the stretch.wrapped foods held at constant temperatures of 0, 5, 10 and $15^{\circ}C$ were measured throughout storage. The bootstrapping method was applied to generate many resampled data sets of mean microbial counts, which were then used to estimate the parameters of the microbial growth model of Baranyi & Roberts in the form of differential equations. The temperature functions of the primary model parameters were set up with confidence limits. Incorporating the temperature dependent parameters into the differential equations of bacterial growth could produce predictions closely representing the experimental data under constant and fluctuating temperature conditions.

• Korean System Dynamics Review
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• v.3 no.1
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• pp.5-42
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• 2002

The main purpose of this paper is analyzing long-term growth possibility of a telecommunication Company (Telco) H. First of all, to achieve this purpose, the precise understanding about causal relations among growth and decay factors of Telco H is required. Based upon the causal analysis, a basic computer simulation model is developed. Finally, several predictive examinations about growth possibility and pattern of the Telco H are conducted using three scenarios. From simulation results, the most important policy leverages are capabilities of market share sustenance, improvement of service quality and squeezing current network facility to elevate profitability and efficiency. Recently, telecommunication industry has become more and more competitive due to introduction of Internet and deregulation. Internet has brought about global competition as well as confusion between telecommunication and broadcasting industries. At the almost same time, deregulation is a universal tendency and a catalyst of unlimited competition. Telco H has been a dominant company in Korea for last century. However, the dominant position of Telco H has been threatened by the change of competition environment. The competitive environment has many elements and keeps changing dynamically. Therefore, System Dynamics simulation methodology is adopted to examine the problem.

• Computational Structural Engineering
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• v.10 no.4
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• pp.229-238
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• 1997

Mechanical behavior of asphalt concrete that accounts for viscoelasticity and damage evolution under cyclic loading conditions is modeled and presented in this paper. An elastic-viscoelastic correspondence principle in terms of pseudo variables is applied to separately evaluate viscoelasticity and time-dependent damage growth in asphalt concrete. A microcrack growth law, which is commonly employed in linear viscoelastic fracture mechanics, is successfully used for describing the damage growth in the body. A constitutive equation in terms of stress and pseudo strain is first established for controlled-strain mode, and then transformed to controlled-stress constitutive equation by simply replacing stress and pseudo strain with pseudo stress and strain. The transformed constitutive equation in terms of pseudo stress satisfactorily predicts the mechanical behavior of asphalt concrete all the way up to failure under controlled-stress modes.

• 한국도로학회:학술대회논문집
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• 2008.10a
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• pp.93-102
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• 2008

An energy based crack growth model is developed in this study to simulate the propagation of top-down cracking in asphalt pavements. A viscoelastic fracture mechanics approach, generalized J integral, is employed to model the crack growth of asphalt concrete. Laboratory fatigue crack propagation tests for three different asphalt mixtures are performed at various load levels, frequencies and temperatures. Disk-shaped specimens with a proper loading fixture and crack growth monitoring system are selected for the tests. It is observed from the tests that the crack propagation model based on the generalized J integral is independent of load levels and frequencies, while the traditional Paris' law model based on stress intensity factor is dependent of loading frequencies. However, both models are unable to take care of the temperature dependence of the mixtures. The fatigue crack propagation model proposed in this study has a good agreement between experimental and predicted crack growth lives, which implies that the energy based J integral could be a better parameter to describe fatigue crack propagation of viscoelastic materials such as asphalt mixtures.

• Nuclear Engineering and Technology
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• v.47 no.7
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• pp.867-874
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• 2015

Separation of cesium chloride (CsCl) and strontium chloride ($SrCl_2$) from the lithium chloride-potassium chloride (LiCl-KCl) salt was studied using a melt crystallization process similar to the reverse vertical Bridgeman growth technique. A ternary $SrCl_2-LiCl-KCl$ salt was explored at similar growth rates (1.8-5 mm/h) and compared with CsCl ternary results to identify similarities. Quaternary experiments were also conducted and compared with the ternary cases to identify trends and possible limitations to the separations process. In the ternary case, as much as 68% of the total salt could be recycled per batch process. In the quaternary experiments, separation of Cs and Sr was nearly identical at the slower rates; however, as the growth rate increased, $SrCl_2$ separated more easily than CsCl. The quaternary results show less separation and rate dependence than in both ternary cases. As an estimated result, only 51% of the total salt could be recycled per batch. Furthermore, two models have been explored to further understand the growth process and separation. A comparison of the experimental and modeling results reveals that the nonmixed model fits reasonably well with the ternary and quaternary data sets. A dimensional analysis was performed and a correlation was identified to semipredict the segregation coefficient.

• Korean Journal of Metals and Materials
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• v.48 no.3
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• pp.187-193
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• 2010

The solute carbon content in ferrite is one of the important factors to obtain good formability in low carbon steels. Although most of the carbons are consumed by the formation of grain boundary cementite during coiling after hot-rolling, the carbon content after coiling is normally observed much more than that of equilibrium. In this study, a classical nucleation and growth model is used to simulate the precipitation kinetics of the grain boundary cementite from coiling temperature (CT) to room temperature (RT). The predicted precipitation behaviors depending on the initial carbon content and the cooling rate are compared with the reported. As a result, the lateral growth of thickening of cementite is a major factor for the sluggish reaction of grain boundary cementite. The reduction of solute carbon content after coiling is divided into three regions: a) increase due to no cementite precipitation, b) decrease due to the fast length-wise growth of cementite, c) increase due to the slow thickness-wise growth of cementite.

• Korean Management Science Review
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• v.17 no.3
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• pp.147-160
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• 2000

These days, a modeling tool or environment has to know about the others on the market and build bridges to them with which their customers insist on sharing models and data. When it is based on a closed architecture, a tangle of import/export point translators is required. Using an exchange standard, we can design an open architecture for the interchange of models and data. XML(Extensible Markup Language) provides a framework for describing the syntax for creating and exchanging data structures. The explosive growth of XML-based business proposals and standards reflects the urgent requirements and its strength. This paper proposes an XML-based language for sharing decision models within the MSOR/DSS community. The language is able to allow applications and on-line analytic processing tools to models obtained from multiple sources without having to deal with individual differences between those sources. It is expected to be a medium for B2B integration by supporting flexible interchange of decision models.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1796-1803
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• 2015

While considering the current scenario, in this world power demand goes on increases day by day. Frequent power outages occur in high voltage transmission line due to the deprived performance of polluted insulators; this affects overall operation of power system and may indirectly impinge on the growth of production sector. Many researchers are keenly taking efforts to provide highly reliable and stable power to neediest. In this paper, A.C pollution flashover performance of disc type glass insulator and composite long rod insulators investigation under various artificial pollutions by varying Equivalent Salt Density Deposition (ESDD) levels. Here, we use different types of pollution methods like binding method, dipping method and spraying methods with different types of pollutants concentration. Based on dimensional analysis, four different Mathematical models have been developed to predict the A.C pollution Flashover Voltage (FOV) of insulators. Both the experimental and mathematically modeled results are compared; it's observed that mathematical model 3 yields better results.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.276-281
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• 2002

A metallurgical model for bainite transformation kinetics in the coarse-grained heat affected zone(CGHAZ) on the basis of an Avrami-type equation was studied. Isothermal transformation tests were carried out to obtain the empirical equations for incubation time and Avrami kinetic constants for C-Mn-Mo-Ni steel. The effect of prior austenite grain size(PAGS) on the reaction rate of bainite was also investigated. Compared with experimental transformation behavior of bainite, the predicted behavior was in good agreement. It was also found that a smaller grain size retard the bainite reaction rate, contrary to the classical grain size effect and this is considered to be caused by constraint of grain size to bainite growth.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.247-252
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• 1996

In the concrete structures, cracks occur in various causes and the cracks seriously affect the functions of structures. The analysis techniques of progressive crack in the concrete have been improved with the advance of numerical techniques. The discrete crack model used in finite element program for the analysis of progressive failure is very effective, but it can not be easily implemented into numerical procedures because of difficult handing of nodal points in finite element meshes for crack growth. This paper introduces one of the techniques which skips the difficulty. In this paper, the modeling of progressive failure using finite element formulation is explained for the analysis of concrete fracture. The discontinuous element using the discontinuous shape function and the dual mapping technique in the numerical integration are implemented into finite element code for this purpose. It is shown that developed finite element program can predict the quasi-brittle behavior of concrete including ultimate load. The comparisons of the analysis results with other data are also shown.