• 산업공학
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• 제15권4호
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• pp.374-381
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• 2002

In this paper, we design and implement a real-time route guidance system(RGS) in large-scale networks. Coupled with the well-known mathematical routing algorithms, we devise an RGS for knowledge aquisition and self-learning ability within the framework of the expert system. Through off-line construction of database, on-line treatment of unexpected traffic accidents, etc., the developed RGS can provide drivers with good quality real-time routing information. The practical effectiveness of the proposed system is demonstrated in terms of response time and route appropriateness.

• Structural Engineering and Mechanics
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• 제51권1호
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• pp.163-180
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• 2014

In the displacement based finite element analysis of composite beams that consist of two Euler-Bernoulli beams juxtaposed with a deformable shear connection, the coupling of the displacement fields may cause oscillations in the interlayer slip field and reduction in optimal convergence rate, known as slip-locking. In this study, the B-bar procedure is proposed to alleviate the locking effects. It is also shown that by changing the primary dependent variables in the mathematical model, to be able to interpolate the interlayer slip field directly, oscillations in the slip field can be completely eliminated. Examples are presented to illustrate the performance and the numerical characteristics of the proposed methods.

• Membrane and Water Treatment
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• 제7권2호
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• pp.87-100
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• 2016

A numerical simulation of membrane evaporation process was carried out in this work. The aim of simulation is to describe transport of water through porous membranes applicable to the concentration of aqueous solutions. A three-dimensional mathematical model was developed which considers transport phenomena including mass, heat, and momentum transfer in membrane evaporation process. The equations of model were then solved numerically using finite element method. The results of simulation in terms of evaporation flux were compared with experimental data, and confirmed the accuracy of model. Moreover, profile of pressure, concentration, and heat flux were obtained and analyzed. The results revealed that developed 3D model is capable of predicting performance of membrane evaporators in concentration of aqueous solutions.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제8권1호
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• pp.33-50
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• 2004

This study is intended to investigate the effect on the development of multiplicative thinking and multiplicative ability by teaching repeated addition, rate, comparison, area-array, and combination problems. Two research questions are established: first, is there any difference of multiplicative thinking between the experimental group(the modeling of problem situation learning group) and the control group(the traditional learning group)\ulcorner Second, is there any difference of multiplicative ability between the experimental group and the control group\ulcorner The treatment process for the experimental group is based on modeling problem situations for nine lesson periods. In order to answer the research questions the chi-square analysis was used for the first research question and the t-test was used for the second one. The findings are summarized as follows: there is no significant difference of multiplicative thinking be1ween the experimental and the control group but there is significant difference of multiplicative ability.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제2권2호
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• pp.103-112
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• 1998

The purpose of this study is to analyze the effects of the Problem Centered Instruction(PCI) and the Explanatory Instruction(El). Two classes of third grade children(69 children) were sampled from an elementary school in Chung-Buk and given a treatment. The results of this study as follows： (1) There was no significant difference between the PCI group and the El group. This means that the PCI doesn't decrease the computational ability, even though the ordinary calculation methods are not taught in the PCI group. (2) The PCI group got scores significantly higher than the El group on application problems. It may be interpreted that the PCI is more effective than the El in problem solving.

• Journal of applied mathematics & informatics
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• 제29권3_4호
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• pp.721-741
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• 2011

In this paper we have considered a dynamical mathematical model of the sub-populations of potential smokers (non-smokers), smokers, smokers who temporarily quit smoking, smokers who permanently quit smoking and a class of smoking associated illness by introducing time dependent parameters and distributed time delay to acquire smoking habit. Here, we have established some sufficient conditions on the permanence and extinction of the smoking class in the community by using inequality analytical technique. We have introduced some new threshold values $R_0$ and $R^*$ and further obtained that the smoking class in the community will be permanent when $R_0$ > 1 and the smoking class in the community will be going to extinct when $R^*$ < 1. By Lyapunov functional method, we have also obtained some sufficient conditions for global asymptotic stability of this model. Computer simulations are carried out to explain the analytical findings. The aim of the analysis of this model is to identify the parameters of interest for further study, with a view to informing and assisting policy-maker in targeting prevention and treatment resources for maximum effectiveness.

• 한국경영과학회지
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• 제4권1호
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• pp.33-39
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• 1979

The cash management problem as a part of working capital management has been extensively studied. By and large the articles surveyed lacked consideration of long-term assets and the proper tax treatment of them. Recognizing that investment activities - long-term as well as short-term generate cash inflows, leads one to conclude that these investments should be included in the cash management problem. The liquidity of long term investments is an integral part of the cash management problem. This paper formulated a cash management model which incorporate the effect of long term investments and their liquidity on cash holdings. Although all of the models formulated could be solved using mathematical programing techniques, the mere size of the problem in terms of the number of variables and constraints leads one to seek other methods. For this reason rules were developed using the Kuhn-Tucker conditions thereby substaintially avoiding the programming calculations or at least easing them significantly.

• Architectural research
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• 제8권2호
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• pp.27-36
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• 2006

Structural uncertainties are generally modeled using probabilistic approaches in order to quantify uncertainties in behaviors of structures. This uncertainty results from the uncertainties of structural parameters. Monte Carlo methods have been usually carried out for analyses of uncertainty problems where no analytical expression is available for the forward relationship between data and model parameters. In such cases any direct mathematical treatment is impossible, however the forward relation materializes itself as an algorithm allowing data to be calculated for any given model. This study addresses a new method which is utilized as a basis for the uncertainty estimates of structural responses. It applies double uniform random numbers (i.e. DURN technique) to conventional Monte Carlo algorithm. In DURN method, the scenarios of uncertainties are sequentially selected and executed in its simulation. Numerical examples demonstrate the beneficial effect that the technique can increase uncertainty degree of structural properties with maintaining structural stability and safety up to the limit point of a breakdown of structural systems.

• 한국유체기계학회 논문집
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• 제14권6호
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• pp.85-90
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• 2011

Recently, many high elevation fountain are constructed for the beauty of beach landscape. Typically, a fountain has several nozzles that shoots water upwards or at an angle into the air. But unfortunately, the weather and wind can cause the water soak nearby walkways and pedestrians. Therefore, in this study, a mathematical model of high elevation fountain is suggested to predict the actual travelling distance of water droplet by the wind. To simplify our treatment of the water flow and to avoid issues such as fluid dynamics and surface tension, we have adopted a particle model for the fountain water. The particles are assumed not to interact with each other, and do not deform during their flight through air.

• Molecular & Cellular Toxicology
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• 제3권2호
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• pp.77-84
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• 2007

Millions of individuals worldwide are currently afflicted with neurodegenerative disorders such as Parkinson's disease and multiple sclerosis which are caused by the death of specific types of specialized cells in the Central Nervous System (CNS). Recently, Neural Stem Cells (NSCs) are able to replace these dead cells with new functional cells, thereby providing a cure for devastating neural diseases. The clinical use of neural stem cells (NSCs) for the treatment of neurological diseases requires overcoming the scarcity of the initial in vivo NSC population. Thus, we developed a novel 3-dimentional cellular automata model for optimum production of neural stem cells and their derivatives in large scale to treat neurodegenerative disorder patients.