• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.4
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• pp.184-191
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• 2009

In a technological driven environment, a depreciation estimate which is based on traditional life analysis results in a decelerated rate of capital recovery. This time pattern of technological growths models needs to be incorporated into life analysis framework especially in those industries experiencing fast technological changes. The approximation technique for calculating the variance can be applied to the six growth models that were selected by the degree of skewness and the transformation of the functions. For the Pearl growth model, the Gompertz growth model, and the Weibull growth model, the errors have zero mean and a constant variance over time. However, transformed models like the linearized Fisher-Pry model, the linearized Gompertz growth model, and the linearized Weibull growth model have increasing variance from zero to that point at which inflection occurs. It can be recommended that if the variance of error over time is increasing, then a transformation of observed data is appropriate.

• Journal of computational fluids engineering
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• v.13 no.4
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• pp.66-71
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• 2008

This research computes the viscous flow field and aerodynamics around the model of a commercial passenger airplane, Boeing 747-400, which cruises in transonic speed. The configuration was realized through the reverse engineering based on the photo scanning measurement. In results, the pressure coefficients at the several wing section on the wing surface of the airplane was described and discussed to obtain the physical meaning. The lift coefficient increased almost linearly up to $17^{\circ}$. Here the maximum lift occurred at $18^{\circ}$ according to the angle of attack. And the minimum drag is expected at $-2^{\circ}$. The maximum lift coefficient occurred at the Mach number 0.89, and the drag coefficient rapidly increased after the Mach number of 0.92. Also shear-stress transport model predicts slightly lower aerodynamic coefficients than other models and Chen's model shows the highest aerodynamic values. The aerodynamic performance of the airplane elements was presented.

• The Journal of the Korea Contents Association
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• v.11 no.4
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• pp.225-234
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• 2011

The purpose of this study was to survey the intervention model, intervention settings, intervention time, factors influencing selection of intervention model, relationship between intervention model and areas which supporting center for special education based occupational therapist was using. Study data were provided by 46 therapy supporting service professionals through e-mail and analyzed. The findings indicated that first, the therapy supporting service professionals often employed a direct therapy(individual) focusing on performance component of child. Second, they believed that direct therapy is most effective in improving children's performance and raising awareness of the importance of occupational therapy. Third, when choose intervention model, they took into consideration the child's performance components deficits and mind of team chief. Fourth, no correlation between the application time and the perception of effectiveness of intervention model. Also didn't find correlation between applying time of intervention model and intervention area. When putting the various research result together, the model school-based occupational therapists using was similar to medical model. Therefore it is need a study to develop effective intervention model and apply it in school environment.

• Elastomers and Composites
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• v.46 no.1
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• pp.54-59
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• 2011

One of the viscoelastic flow behaviors during profile extrusion is the swelling of extrudate. In this study, die swell of rubber compound in the capillary die have been investigated through experiment and computer simulation. Simplified viscoelastic model and non-linear differential viscoelastic model such as PTT model have been used in the computer simulation. The simulation results have been compared with experimental data. Experiment and simulation have been performed using fluidity tester and commercial CFD code, Polyflow respectively. Die swells predicted by two models showed good agreement with experimental results. Pressure and velocity distribution, and circulation flow at the corner of reservoir have been well predicted by PTT model. Simplified viscoelastic model can not predict circulation flow at the corner of reservoir. However this model has an advantage in computation time compare with full viscoelastic model, PTT model.

• Journal of the Ergonomics Society of Korea
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• v.35 no.5
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• pp.371-381
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• 2016

Objective:This study aims to evaluate the features of heart rate variability (HRV) and respiratory signals as indices for a driver's drowsiness and waking status in order to develop the classification model for a driver's drowsiness and waking status using those features. Background: Driver's drowsiness is one of the major causal factors for traffic accidents. This study hypothesized that the application of combined bio-signals to monitor the alertness level of drivers would improve the effectiveness of the classification techniques of driver's drowsiness. Method: The features of three heart rate variability (HRV) measurements including low frequency (LF), high frequency (HF), and LF/HF ratio and two respiratory measurements including peak and rate were acquired by the monotonous car driving simulation experiments using the photoplethysmogram (PPG) and respiration sensors. The experiments were repeated a total of 50 times on five healthy male participants in their 20s to 50s. The classification model was developed by selecting the optimal measurements, applying a binary logistic regression method and performing 3-fold cross validation. Results: The power of LF, HF, and LF/HF ratio, and the respiration peak of drowsiness status were reduced by 38%, 22%, 31%, and 7%, compared to those of waking status, while respiration rate was increased by 3%. The classification sensitivity of the model using both HRV and respiratory features (91.4%) was improved, compared to that of the model using only HRV feature (89.8%) and that using only respiratory feature (83.6%). Conclusion: This study suggests that the classification of driver's drowsiness and waking status may be improved by utilizing a combination of HRV and respiratory features. Application: The results of this study can be applied to the development of driver's drowsiness prevention systems.

• Korean Journal of Childcare and Education
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• v.15 no.6
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• pp.117-137
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• 2019

Objective: The purpose of this study was to investigate the effects of a cyclical empathy model-based empathy enhancement program on young children's empathy, peer competence and emotional intelligence. Methods: A total of 40 subjects were selected for this study from 5-year-old children attending S Day Care Center located in Seoul, out of whom 20 were assigned to an experimental group and the remaining 20 to a comparative group (control group). The SPSS 21 statistical program was used to determine whether there was a significant difference between the two groups in the effectiveness of the program implementation. Results: There were statistically significant differences in the changes between the pre and post scores of the experimental group and the comparative group, which showed that the cyclical empathy model-based empathy enhancement program was effective for the young children's empathy, peer competence and emotional intelligence. Conclusion/Implications: This study suggests that if a young children's empathy enhancement program can be applied to child care sites to help the teachers in the field children can overcome empathy-related difficulties by themselves. This study also provides basic information in order to have meaningful educational experiences in young children's education institutions.

• 한국경영정보학회:학술대회논문집
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• 2008.06a
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• pp.454-471
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• 2008

This study suggests the dynamic pricing model which reveals the organic relationship between ASP (Application Service Provider) price and the related factors, using system dynamics methodology. Basically, we applied the law of supply and demand for analyzing price changes. Then, we deducted ASP price, focusing on fixed cost and variable cost. We also researched the customer's buying behavior according to version differentiation policy. In the version policy, we set up the proposition about customer's satisfaction and willingness-to-pay, using option system. As a result, this research designed the simulation model which analyzes the changes of the sales according to version differentiations and customer's willingness-to-pay. Through this research, we can find effective version differentiation strategies. This paper also found that the larger the number of package, the greater the demand and customer's willingness-to-pay. The increase of the number of package causes the increase of the sales. The increase of the sale is not exactly relative to the number of package. Drawing S-curve, the sales was increased. This dynamic pricing model suggests the ground that the ASP price changes based on the existing version differentiation theory and the demand of customers can affect the changes of the sales. We expect that this model suggests a clear standard of ASP pricing by combining real cases.

• Journal of information and communication convergence engineering
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• v.7 no.2
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• pp.92-97
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• 2009

Lately, influence of information rises and interest about satisfaction estimation of information providing service is risin. According to rapid change in information environment, information-providing service is being changed in various form, in which center development is made in relation to the effort for customer satisfaction intended to enhance user's satisfaction level through providing more convenient and higher service centered on information service user rather than information service provider. Organizations providing information service is also changing their service from traditional one centered on service provider to that for user's satisfaction and service quality, and evaluation of information service quality and measurement of user's satisfaction as the result of using information service are regarded important. In this respect, it is needed to measure user's satisfaction level for environmental factors of information service and analyze what kind of influence they have to enhance user's satisfaction level of information service. Also function and efficiency of information offer service are important. Therefore, interest for satisfaction survey to heighten contents satisfaction of information-providing service, service satisfaction, satisfaction of user of system satisfaction is increased. In this paper, we propose a model of the user satisfaction index for information-providing services and present the user satisfaction index is measured to the model. Also we this study suggest qualitative improvements of information-providing service required for change to user-centric information-providing service through measuring user satisfaction index of ITFIND system and schemes to improve information quality

• Journal of Ubiquitous Convergence Technology
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• v.2 no.2
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• pp.97-104
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• 2008

In this paper, we demonstrate the boundary effect of a deployed regions on the effective coverage of a mobile node. A node coverage area is not uniform throughout the entire deployed region. Assuming a uniform coverage can result in significant error in calculations. In this study, we analyze the behavior of a node's coverage area as a function of its transmission range throughout the entire deployed region. Using this analysis, a mathematical model for effective coverage in mobile wireless communications is created. The mathematical model considers the effect of the deployed regions boundaries on the coverage area of a mobile node. Lastly, we present simulation results to verify the analytical model and to compare this model with that of a uniform coverage.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.12
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• pp.75-78
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• 1994

Clinically, proximal bone resorption in the femur is frequently seen postoperatively on the follow up X-rays after total hip replacement(THR). We developed the finite element model of cementless THR. The model is two dimensional side plate model, whereby the three dimensional structural integrity of the bone can be accounted for by a separate two dimensional mesh, a side plate. The subject of this article is the development and application of this two dimensional side plate FEM to study the reverse effect of the various degree of bone resorption of femur after THR. The results of this study indicates that two dimensional side plate model is good and simple alternative to complex three dimensional model and the severity of the proximal bone resorption has the effect of more increasing stress on the cortex at the level of femoral stem tip.