• 경영과학
• /
• 제23권3호
• /
• pp.157-182
• /
• 2006

Increasing attention has been paid to the home network business in Korea. The rate of growth of the business, however, has not been as high as it was expected. In this study we first categorize the business into three classes of services, with five distinct players. The business models of the five players differ from each other, which in turn keeps the business from visible growth. Based on this observation, we applied business alliance theories to the home network business to find out ways to make the players cooperate with each other. And we proposed five cooperation strategies for three different classes of home network services. Finally we made some suggestions to remove obstacles against business cooperation among the players.

• Nuclear Engineering and Technology
• /
• 제44권8호
• /
• pp.889-896
• /
• 2012

Recent progress in the computational fluid dynamics methods of two- and multiphase phase flows has already started opening up new exciting possibilities for using complete multidimensional models to simulate boiling systems. Combining this new theoretical and computational approach with novel experimental methods should dramatically improve both our understanding of the physics of boiling and the predictive capabilities of models at various scale levels. However, for the multidimensional modeling framework to become an effective predictive tool, it must be complemented with accurate mechanistic closure laws of local boiling mechanisms. Boiling heat transfer has been studied quite extensively before. However, it turns out that the prevailing approach to the analysis of experimental data for both pool boiling and forced-convection boiling has been associated with formulating correlations which normally included several adjustable coefficients rather than based on first principle models of the underlying physical phenomena. One reason for this has been the tendency (driven by practical applications and industrial needs) to formulate single expressions which encompass a broad range of conditions and fluids. This, in turn, makes it difficult to identify various specific factors which can be independently modeled for different situations. The objective of this paper is to present a mechanistic modeling concept for both pool boiling and forced-convection boiling. The proposed approach is based on theoretical first-principle concepts, and uses a minimal number of coefficients which require calibration against experimental data. The proposed models have been validated against experimental data for water and parametrically tested. Model predictions are shown for a broad range of conditions.

• 한국경영과학회지
• /
• 제35권4호
• /
• pp.33-53
• /
• 2010

When purchase prices of a raw material fluctuate over time, the total purchasing cost is mainly affected by reordering time. Existing researches focus on deciding the right time when the demand for each period is replenished at the lowest cost. However, the decision is based on expected future prices which usually turn out to include some error. This discrepancy between expected prices and actual prices deteriorates the performance of inventory models dealing with fluctuating purchase prices. In this paper, we propose a new inventory model which incorporates not only cost but also risk into making up a replenishment schedule to meet each period's demand. For each replenishment schedule, the risk is defined to be the variance of its total cost. By introducing the risk into the objective function, the variability of the total cost can be mitigated, and eventually more stable replenishment schedule will be obtained. According to experimental results from crude oil inventory management, the proposed model showed better performance over other models in respect of variability and cost.

• Journal of Mechanical Science and Technology
• /
• 제20권11호
• /
• pp.1891-1897
• /
• 2006

In this study, a new model to predict the effective elastic constants of composites with spherical fillers is proposed. The original Eshelby model is extended to a finite filler volume fraction without using Mori-Tanaka's mean field approach. When single filler is embedded in the matrix, the effective elastic constants of the composite are computed. The composite is in turn considered as a new matrix, where new single filler is again embedded in the matrix. The predicted results by the present model with a series of embedding procedures are compared with those by Mori-Tanaka, self-consistent, and generalized self-consistent models. It is revealed through parametric studies such as stiffness ratio of the filler to the matrix and filler volume fraction that the present model gives more accurate predictions than Mori-Tanaka model without using the complicated numerical scheme used in self-consistent and generalized self-consistent models.

• 한국산업정보학회논문지
• /
• 제6권2호
• /
• pp.63-73
• /
• 2001

An alternative approach to formulating a special class of linear goal programming (LGP) models is presented. We propose a formulation of the LGP model that can include the decision variables in the objective function. We specifically propose that the position of the decision variables in the objective function be used to eliminate goal constraints whose sole purpose is to indirectly optimize decision variables. For the select group of LGP problems wherever indirect optimization of decision variables are sought, the alternative LGP model formulation is able to reduce the size of these LGP models and in turn the computational effort required for their solution.

• Asia pacific journal of information systems
• /
• 제30권3호
• /
• pp.457-496
• /
• 2020

This study aims to extensively analyze the performance of various Machine Learning (ML) techniques for predicting version to version change-proneness of source code Java files. 17 object-oriented metrics have been utilized in this work for predicting change-prone files using 31 ML techniques and the framework proposed has been implemented on various consecutive releases of two Java-based software projects available as plug-ins. 10-fold and inter-release validation methods have been employed to validate the models and statistical tests provide supplementary information regarding the reliability and significance of the results. The results of experiments conducted in this article indicate that the ML techniques perform differently under the different validation settings. The results also confirm the proficiency of the selected ML techniques in lieu of developing change-proneness prediction models which could aid the software engineers in the initial stages of software development for classifying change-prone Java files of a software, in turn aiding in the trend estimation of change-proneness over future versions.

• Computers and Concrete
• /
• 제17권3호
• /
• pp.353-386
• /
• 2016

Realistic assessment of the performance of reinforced concrete structural members like columns is needed for designing new structures or maintenance of the existing structural members. This assessment requires analytical capability of employing proper material models and cyclic rules and considering various load and displacement patterns. A computer application was developed to analyze the non-linear, cyclic flexural performance of reinforced concrete structural members under various types of loading paths including non-sequential variations in axial load and bi-axial cyclic load or displacement. Different monotonic material models as well as hysteresis rules, were implemented in a fiber-based moment-curvature and in turn force-deflection analysis, using proper assumptions on curvature distribution along the member, as in plastic-hinge models. Performance of the program was verified against analytical results by others, and accuracy of the analytical process and the implemented models were evaluated in comparison to the experimental results. The computer application can be used to predict the response of a member with an arbitrary cross section and various type of lateral and longitudinal reinforcement under different combinations of loading patterns in axial and bi-axial directions. On the other hand, the application can be used to examine analytical models and methods using proper experimental data.

• 한국생산제조학회지
• /
• 제22권6호
• /
• pp.1025-1031
• /
• 2013

A library of parametric CAD models should be provided for the reuse of design data in configuration design. Mechanical products have many options and parameters, which in turn, require a large number of CAD models for configuration designs. Existing methods for library construction are limited in their ability to decrease the number of CAD models and ensure independency between the configuration design system and the library. To solve these problems, we propose a method that controls a CAD library based on part-shape information model, and also present its technical details. To verify the proposed method, a CAD library for bicycles was constructed and design modification experiments using a prototype part-shape controller were performed. From the experiments, we found that the proposed method can effectively decrease the required number of CAD models by reusing models for configuration designs.

• 복식문화연구
• /
• 제17권3호
• /
• pp.459-471
• /
• 2009

The purpose of the study is to examine the effect of VMD image appropriateness in apparel shopping contexts. Two competing models are utilized. The first model is developed from the emotion-cognition theory which explains that environmental cues(i.e., VMD image appropriateness) generate consumers' emotion, and in turn, consumers' behaviors. The second model is developed based on the cognitive theory of emotions and posits that environmental cues stimulates consumers' cognitive perceptions of retail environments, subsequently influencing consumers' emotional and behavioral response. A 2(VMD image appropriateness: high vs. low) between-subjects factorial design experiment was conducted. Female college students(n=592) participated in the experiment. Using structural equation modeling the study found that the emotion-cognition model better explains the effect of VMD image appropriateness on consumers' emotional, cognitive, and behavioral responses.

• Journal of Power Electronics
• /
• 제16권2호
• /
• pp.778-785
• /
• 2016

An excess carrier lifetime extraction method is derived for physics-based insulated gate bipolar transistor (IGBT) models with consideration of the latest development in IGBT modeling. On the basis of the 2D mixed-mode Sentaurus simulation, the clamp turn-off test is simulated to obtain the tail current. The proposed excess carrier lifetime extraction method is then performed using the simulated data. The comparison between the extracted results and actual lifetime directly obtained from the numerical device model precisely demonstrates the accuracy of the proposed method.