• Proceedings of the Korean Society for Bioinformatics Conference
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• 2005.09a
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• pp.373-378
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• 2005

The diagrammatic language for pathways is widely used for representing systems knowledge as a network of causal relations. Biologists infer and hypothesize with pathways to design experiments and verify models, and to identify potential drug targets. Although there have been many approaches to formalize pathways to simulate a system, reasoning with incomplete and high level knowledge has not been possible. We present a qualitative formalization of a pathway language with incomplete causal descriptions and its translation into propositional temporal logic to automate the reasoning process. Such automation accelerates the identification of drug targets in pathways.

• Communications of the Korean Mathematical Society
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• v.33 no.3
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• pp.1039-1048
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• 2018

In this paper we study the dynamics of a general ${\omega}-periodic$ model. Necessary and sufficient conditions for the global stability of zero steady state of the model are given. The conditions under which there exists a unique periodic solutions to the model are determined. We also show that the unique periodic solution is the global attractor of all other positive solutions. Some applications to mathematical models for cancer and tumor growth are given.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.1
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• pp.138-152
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• 2007

There has been much effort to improve the accuracy of the Internet topology model and include its quantitativeand/or qualitative effects on studies of a variety of network problems. Such improvement is the primarymotivation of this paper in listing and classifying the body of literature addressing the Internet topology. Themetrics, which characterize the fundamental properties of the Internet, are also divided into five categories andtheir importance and applications are discussed. Finally, we suggest several future research topics for theInternet topology models to be more realistic and applicable.

• Journal of Korean Institute of Industrial Engineers
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• v.22 no.2
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• pp.209-229
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• 1996

Scheduling problems which determine the sequence of jobs are one of the Important issues to many industries. This paper deals with a single-machine job sequencing problem which has complex constraints and an objective function. To solve the problem, an expressive constraint description language and an automatic code generator are developed for our scheduling system. The user just needs to describe the scheduling problem using the constraint description language that allows to express both quantitative and qualitative constraints as well as an objective function in real world semantics. Then, a complete scheduling program based on constraint satisfaction technique is automatically generated through the code generator. Advantage of this approach is that models of the scheduling problems are easily developed and maintained because models ore formulated by using the language which reflects real world semantics.

• International Journal of Automotive Technology
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• v.5 no.3
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• pp.145-153
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• 2004

Potential fuel economy improvements and environmental legislation have renewed interest in Gasoline Direct Injection (GDI) engines. Computational models of fuel injection and mixing processes pre-ignition are being developed for engine optimisation. These highly transient thermofluid models require verification against temporally and spatially resolved data-sets. The authors have previously established the capability of PDA to provide suitable temporally and spatially resolved spray characteristics such as mean droplet size, velocity components and qualitative mass distribution. This paper utilises this data-set to assess the predictive capability of a numerical model for GDI spray prediction. After a brief description of the two-phase model and discretisation sensitivity, the influence of initial spray conditions is discussed. A minimum of 5 initial global spray characteristics are required to model the downstream spray characteristics adequately under isothermal, atmospheric conditions. Verification of predicted transient spray characteristics such as the hollow-cone, cone collapse, head vortex, stratification and penetration are discussed, and further improvements to modelling GDI sprays proposed.

• Journal of Agricultural Extension & Community Development
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• v.16 no.1
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• pp.69-98
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• 2009

This study empirically studies the effects of Agricultural Technology Service Center's educational program for farmers on their incomes. The educational program for farmers has widely been managed in discourse and policy in Korea. In 2008, Agricultural Technology Service Center managed 88 educational program for farmers, where 6,409 farmers received a certificate. While there are important studies, most of them have concentrated on qualitative analysis and noneconomic effects to an educational program for farmers. This study tried to analyze whether or not there is an economic effect of an educational program for farmers, focusing on the relationship between the educational program for farmers and their income status. Multilevel models (or hierarchical linear models) were applied to this study. Multilevel model is a quantitative model of parameters that vary at more than one level and show hierarchical structures between levels. This study particularly accentuates that an educational program for farmers is more meaningful when it can raise farmers' incomes by region and by educational program for farmers.

• Journal of the Ergonomics Society of Korea
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• v.9 no.2
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• pp.47-54
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• 1990

These are preisely the controlling foators that we must deal with and measure in order to get relatistic answers. We must stop making simplifying assumptions to suit our quqntitative models man deal with complex situations. To be relistic our models must include and measure all important tangible and intangible, quantitatively measureable, and qualitative factors. This is precisely what we do with the analytic hierarchy process (AHP). In this paper, the statistics of industrial accidents are classified with its causes, and safety organization in D heavy industry company be evaluated by Analytic hierarchy model. The influence weight of level of safety organization can be ordered supervisor (0.364), operator (3.10), top manager (0.232) and executive (o.164) by AHP.

• Proceedings of the Korean Institute of Interior Design Conference
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• 1999.04a
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• pp.94-97
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• 1999

The purpose of this study was to prepare the visual communication tool, which would be used for the interior design consulation to reduce the communication gap between an interior designer and a client. To achieve the study purpose, review of literature, questionnaire survey, qualitative analysis and design research methods were used. The major results of this study were as follows: 1) "Image Cube" was designed as a comprehensive rule to classify interior image types. By this, eight interior image types were classified: SFU(Simple-Formal-Urbane), SFN(Simple-Formal-Natural), SCU(Simple-Casual-Urbane), SCN(Simple-Casual-Natural), DFU(Decorative-Formal-Urbane), DFN(Decorative-Formal-Natural), DCU(Decorative-Casual-Urbane), DCN(Decorative-Casual-Natural). 2) The Interior image collages were composed to present the overall feeling of each interior image type. 3) The Interior image models which would be used as the standard to be modified to various sub-types through the interior design consultation were produced corresponding to interior image types.age types.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.734-741
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• 2002

The importance of efficient Supply Chain Management is increasing in accordance with recent industrial environment, such as globalization of business, complexity and diversity of company's management structure, and variety of customer's demand. In a rapidly changed environment of business, quick and efficient decision making is the important matter to the survival of the company. The purpose of this study supports decision making for efficient supply chain management. In this study, we consider simultaneously and mutually reflecting the preference of each constituent (Supplier, Manufacturing plant, Distribution center, Customer) on supply chain network, and decide company's strategic choice and coordinated production/distribution models of company. The Analytical Hierarchy Process is used for decision making of qualitative and quantitative elements. We use the results of AHP as inputs and propose mathematical models thru Mixed Integer Programming.

• Journal of the Korean Mathematical Society
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• v.58 no.1
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• pp.45-67
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• 2021

In this paper, a mathematical dynamical system involving both deterministic (with or without delay) and stochastic "SIR" epidemic model with nonlinear incidence rate in a continuous reactor is considered. A profound qualitative analysis is given. It is proved that, for both deterministic models, if ��d > 1, then the endemic equilibrium is globally asymptotically stable. However, if ��d ≤ 1, then the disease-free equilibrium is globally asymptotically stable. Concerning the stochastic model, the Feller's test combined with the canonical probability method were used in order to conclude on the long-time dynamics of the stochastic model. The results improve and extend the results obtained for the deterministic model in its both forms. It is proved that if ��s > 1, the disease is stochastically permanent with full probability. However, if ��s ≤ 1, then the disease dies out with full probability. Finally, some numerical tests are done in order to validate the obtained results.