• Journal of Information Processing Systems
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• v.17 no.3
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• pp.630-644
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• 2021

Educational data analysis is attracting increasing attention with the rise of the big data industry. The amounts and types of learning data available are increasing steadily, and the information technology required to analyze these data continues to develop. The early identification of potential dropout students is very important; education is important in terms of social movement and social achievement. Here, we analyze educational data and generate predictive models for student dropout using logistic regression, a decision tree, a naïve Bayes method, and a multilayer perceptron. The multilayer perceptron model using independent variables selected via the variance analysis showed better performance than the other models. In addition, we experimentally found that not only grades but also extracurricular activities were important in terms of preventing student dropout.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.210-212
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• 2015

The growth-share matrix is a portfolio planning tool developed by the Boston Consulting Group (BCG) to assist competitive positioning in the international market including those in the construction industry. This matrix is helpful in balancing the firm's cash-flow, and it can suggest strategic directions for each business unit. However, its effectiveness and applicability have long been debated in the academic field due to the complex and unique industrial context of construction. To solve the dispute, this research clarifies the applicability of theories underlying the growth-share matrix to the construction industry. Empirical research based on actual financial data of Korean construction firms is adopted for the statistical analysis including one-way analysis of variance and correlation analysis. The results of this research show that empirical findings on the relationship between performance variables. In this context, this research can provide important insights on the concept of portfolio management in the construction industry.

• Journal of muscle and joint health
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• v.5 no.2
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• pp.206-221
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• 1998

The purpose of this study was to validate translated Multidimensional Assessment of Fatigue(MAF) scale. The scale is a 16-item scale that measures four dimensions of fatigue : severity, distress, impact, timing. Fourteen items are numerical rating scales and 2 items have multiple choice responses. Data were collected from the 137 patients with rheumatoid arthritis after content validation. Criterion validity was tested by correlation coefficient with Piper Fatigue Scale, which resulted in 0.7573(p<.0000). Construct validity was tested by item analysis and factor analysis. Corrected item-total correlation coefficients were 0.63-0.88. And factor analysis showed 2 factors : fatigue degree factor and fatigue impact factor. These two factors explained 73.5% of total variance. Reliability of internal consistency was 0.96 in Cronbach's alpha. Further validation study is necessary in each factor in other settings with other subjects.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2001.10a
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• pp.171-174
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• 2001

This study investigates the differences in critical dimensions which impact on operations and strategy in Internet EC of service related intangible product. For this purpose, services are newly classified by two selected dimensions such as 1)the proportion of substitute by on-line, and 2)the needs of interaction and customization. Secondly, on the classification of services, the differences of 1) customer needs of geographical accessibility, 2) needs of cooperation with off-line functions, and 3) customer purchase intention in Internet EC are tested among classified groups. Finally, implementations on operations and strategy in Internet EC are suggested, based on the results of analysis. Data are collected by the survey on the customer groups, and analyzed by statistical method, such as mean score plot, cluster analysis, and analysis of variance.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.198-206
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• 1999

An automobile outside rear view mirror system has been analyzed and designed to reduce vibration with a finite element model. model analysis is conducted for the calculation of natural frequencies. harmonic analysis is utilized to estimate the displacements of the glass surface under dynamic loads. The model is verified with the vibration experiment of the parts and the assembled body. The structure of the mirror system is optimized for the robustness defined by the Taguchi concept. At first, many potential design variables are defined. Final design variables are selected based on the amount of contribution on the objective function. That is, sensitive variables are chose. The SN ratio in the Taguchi method is replaced by an objective function with the mean and the standard deviation of the quality characteristic. The defined objective function is appropriate in the structural design in that the vibration displacements are minimized while the robustness is improved.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.1
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• pp.28-33
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• 2011

In this paper, structural design for 2kW class composite blade is performed by using design of experiment(DOE). A full factorial design is applied to meet the design specifications at the manufacturing process. The analysis of variance(ANOVA) is made in order to determine the significance of effects in an analysis. Structural analysis by using of commercial software ABAQUS is performed to compute the displacement and safety factor of filament wound composite blade. The results show that the proposed method is suitable to analyze the factors at the design of wind turbine blade.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.755-760
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• 2012

In this study, three dimensional cutting force components and surface roughness appeared in high speed cutting by using tungsten carbide endmill tools implanted ion or not found mutual relations through several analysis of statistical dispersion. It is showed that cutting force(Fx) is affect with spindle speed and feed rate, cutting force(Fy) is affect with spindle speed and ion implantation time and cutting force(Fz) is affect with feed rate in interaction through the statistical method of ANOVA of cutting force and surface roughness, it is analyzed that it is affected of spindle speed and feed rate in surface roughness.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.422-422
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• 2009

This paper describes the structural design of small wind turbine blade by using design of experiments. Blade structure consists of skin, spar and foam. The materials for skin and spar are a kind of Glass/Epoxy and form is polyurethane. It has 7 lay-ups with different ply angle. A factorial design is applied to design the ply angles considering manufacturing constraints and to investigate the safety factor which is calculated by structural analysis. In order to perform the structural analysis, the commercial software ABAQUS is used. Tsai-Wu failure criterion is chosen to compute safety factor. The determination of the significance of effects in the experiments is made through the analysis of variance. The results show that ply angle at skin affects the safety factor of wind turbine blade. And from this result, optimal ply angles of composite blade are achieved.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.157-162
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• 2003

This Paper presents a robust design of an Electrorheological(ER) damper using Taguchi method. Taguchi method is a robust design method that determines control parameters in the presence of noise effect. Electrode length, electrode gap, base oil viscosity and the weight ratio of ER particles are chosen for the control parameters and the temperature is considered to be a noise factor. The sensitivity of each factor with signal-to-noise(S/N) ratio and analysis of variance are investigated. The analysis results show that the electrode length and base oil viscosity of the ER fluid mostly affect the damping force in the absence of electric field. On the other hand, when the voltage is applied to the ER damper, the electrode length and the weight ratio of ER fluid exhibit significant effect. Based on the Taguchi method, an optimal configuration was designed and the robustness of the designed ER damper was validated by comparing the analysis and experimental results.

• Structural Engineering and Mechanics
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• v.14 no.5
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• pp.505-520
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• 2002

Based on the modal coordinates of the structure, a finite-element and CQC (complete quadratic combination) method for analyzing the coupled buffeting response of long-span bridges is presented. The formulation of nodal equivalent aerodynamic buffeting forces is derived based on a reasonable assumption. The power spectral density and variance of nodal displacements and elemental internal forces of the bridge structure are computed using the finite-element method and the random vibration theory. The method presented is very efficient and can consider the arbitrary spectrum and spatial coherence of natural winds and the multimode and intermode effects on the buffeting responses of bridge structures. A coupled buffeting analysis of the Jiangyin Yangtse River Suspension Bridge with 1385 in main span is performed as an example. The results analyzed show that the multimode and intermode effects on the buffeting response of the bridge deck are quite remarkable.