• Journal of Korean Society of Water and Wastewater
• /
• v.13 no.3
• /
• pp.42-55
• /
• 1999

A mathematical model for biological nutrient removal in a sequencing batch reactor process, which is based on the IAWQ Activated Sludge Model No. 2 with a few modifications, has been developed. Twenty water quality components and twenty three kinetic equations are incorporated in the model. The model is structured in the matrix form based on the law of mass conservation using stoichiometry and kinetic equations. Stoichiometric coefficients and kinetic parameters included in the model equations are chosen from the literature. A multistep predictor-corrector algorithm of variable step-size is adopted for solving the vector nonlinear ordinary differential equations. The simulation for experimental results is conducted to evaluate the validity of the model and to calibrate coefficients and parameters. The simulation using the model well represents the experimental results from laboratory. The mathematical model developed in this study may be utilized for the design and operation of a sequencing batch reactor process under the steady and unsteady-state at various environmental conditions.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.33 no.3
• /
• pp.145-153
• /
• 2015

This study aims to accurately estimate population distribution more specifically than administrative unites using a RK (Regression-Kriging) model. The RK model is the areal interpolation technique that involves linear regression and the Kriging model. In order to estimate a population’s distribution using a sample region, four different models were used, namely; a regression model, RK model, OK (Ordinary Kriging) model and CK (Co-Kriging) model. The results were then compared with each other. Evaluation of the accuracy and validity of evaluation analysis results were the basis RMSE (Root Mean Square Error), MAE (Mean Absolute Error), G statistic and correlation coefficient (ρ). In the sample regions, every statistic value of the RK model showed better results than other models. The results of this comparative study will be useful to estimate a population distribution of the metropolitan areas with high population density

• Computers and Concrete
• /
• v.33 no.2
• /
• pp.147-162
• /
• 2024

This study presents a random-aggregate mesoscale model integrating the random distribution of the coarse aggerates and the damage mechanics of the mortar and interfacial transition zone (ITZ). This mesoscale model can generate the random distribution of the coarse aggregates according to the prescribed particle size distribution which enables the automation of the current methodology with different coarse aggregates' distribution. The main innovation of this work is to propose the "correction factor" to eliminate the dimensionally dependent mesh sensitivity of the concrete damaged plasticity (CDP) model. After implementing the correction factor through the user-defined subroutine in the randomly meshed mesoscale model, the predicted fracture resistance is in good agreement with the average experimental results of a series of geometrically similar single-edge-notched beams (SENB) concrete specimens. The simulated cracking pattern is also more realistic than the conventional concrete material models. The proposed random-aggregate mesoscale model hence demonstrates its validity in the application of concrete fracture failure and statistical size effect analysis.

• Journal of Science Education
• /
• v.42 no.3
• /
• pp.308-321
• /
• 2018

The purpose of the study is to develop a questionnaire that examines unskeptical attitudes in scientific inquiry context. The questionnaire items were developed through literature research, expert review, and statistical analyses for validity and the differences in scores were identified by gender and tracks. A total of 363 high school students participated in the study. To explore the validity evidence of items, the Rasch analysis and the reliability of internal consistency were performed, and the two-way ANOVA was performed to compare the scores of the unskeptical attitudes between gender and academic track. Self-reporting and Likert-scaling 23 items were developed to measure unskeptical attitudes in scientific inquiry context. The items were developed in the sub-domain of scientific inquiry: 'questioning and hypothesis generating,' 'experiment designing,' and 'explaining and interpreting.' Second, the validity and reliability of the unskeptical were identified in a rigorous method. The validity of items were identified by multi-dimensional partial score model analysis through the Rasch model, and all 23 items were found to be fit to model. Various reliability evidences were also found to be appropriate. It was found that there were no significant differences of unskeptical attitude score between the gender and academic track except one comparison. The developed questionnaire could be used to check an unskeptical attitude in the course of scientific inquiry and to compare the effects of scientific inquiry classes.

• Journal of Internet Computing and Services
• /
• v.17 no.5
• /
• pp.141-150
• /
• 2016

This study proposed the concept model of ICT-based Creative Talented Persons as the type of persons that gifted education in the ICT area should cultivate for the 21st century. The model of ICT-based Creative Talented Persons is made of three dimensions by 3 core competencies, 9 traits, and 27 characteristics. The field experts, that is, teachers on elementary and secondary school levels evaluate the validity of the model. Teachers expressed positive opinions about the validity of the multi-dimension model of ICT-based Creative Talented Persons. We expect that this model can provide a useful guide to designing and operating ICT education and ICT gifted education for cultivating talented persons to contribute for the future society.

• Communications of Mathematical Education
• /
• v.30 no.1
• /
• pp.1-22
• /
• 2016

We had a full scale of literature survey and case survey of mathematics Flipped Learning class models. The purpose of this study is to design and adopt a Flipped Learning 'Linear Algebra' class model that fis our need. We applied our new model to 30 students at S University. Then we analyzed the activities and performance of students in this course. Our Flipped Learning 'Linear Algebra' teaching model is followed in 3 stages : The first stage involved the students viewing an online lecture as homework and participating free question-answer by themselves on Q&A before class, the second stage involved in-class learning which researcher solved the students' Q&A and highlighted the main ideas through the Point-Lecture, the third stage involved the students participating more advanced topic by themselves on Q&A and researcher (or peers) finalizing students' Q&A. According to the survey, the teaching model made a certain contribution not only to increase students' participation and interest, but also to improve their communication skill and self-directed learning skill in all classes and online. We used the Purposive Sampling from the obtained data. For the research's validity and reliability, we used the Content Validity and the Alternate-Form Method. We found several meaningful output from this analysis.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.12
• /
• pp.5963-5973
• /
• 2011

Current design and analyzing methods about soil nailing structures, developed on the basis of results obtained from experiments in laboratory or in field and numerical analyses, have applied different interaction mechanisms between the reinforced nails and the surrounding ground, and different safety factors against failure have been obtained. They might be proper approaches if the assumptions about rigidity of nails and ground conditions are met with actual conditions occurred in field. Otherwise, they would result in designing on analyzing in inappropriate ways so that it is needed to evaluate the validity of them. Therefore, in this research using the Centrifugal Model Testing, numerical parameters experiments about soil nailing structures' behavior and failure mechanism were performed. In the numerical parameters experiments, transmuted nail's length, setting angle, nail's front panel, stiffness variously, and increased the level of gravity until wall model was destroyed. Based on experimental results, we compared the effect, failure mechanism caused from parameters changes. By reviewing and comparing centrifugal model test results and methods currently in use, verified validity of existing methods.

• Asia Pacific Journal of Business Review
• /
• v.6 no.2
• /
• pp.27-60
• /
• 2022

Previous studies stated that low carbon innovation performance could be influenced by government regulations and the green market, which is the new trend of consumer consumption in the present time, mainly focusing on external factors. Before study augured that low carbon innovation performance could be driven by internal and external factors of cooperation such as institutional pressure, stakeholder pressure, and innovation resources. However, the study of green transformational leadership and organizational environmental culture on low carbon innovation performance is rare, especially in Chinese manufacturing, as well as the effect of influencing factors of TPB model: environmental attitude, subjective norm, and perceived behavior capability on low carbon innovation performance. Previous studies mostly used the TPB model for predicting individual behavior. This study established a theoretical model combining the TPB model with green transformational leadership and organizational environmental culture of Chinese automobile manufacturing on low carbon innovation performance. This study consists of two sections of research methodology: section 1 related to questionnaire design and data collection. We established a questionnaire and distributed it online, targeting responses from the managerial level working in Chinese automobile manufacturing. Eventually, 155 valid questionnaires were used for analysis. Section 2 involved data analysis using statistical software. Reliability and data validity was examined by reliability analysis and factor analysis. Correlations and convergent validity analyses were applied, and structural equation modeling was conducted to test the proposed hypotheses. The findings indicated that green transformational leadership, organizational environmental culture, and essential factors of TPB model; environmental attitude, subjective norm and perceived behavior capability positively affect low carbon innovation performance. In addition, the indirect effect of green transformational leadership was tested and found that organizational environmental culture and TPB factors mediated the relationship between transformational leadership and low carbon innovation performance.

• Journal of Industrial Technology
• /
• v.21 no.B
• /
• pp.273-280
• /
• 2001

In this study, a driver model based on the lead-lag controller for stable maneuver of a highly nonlinear, multi-dimensional, numerically stiff multibody vehicle model according to the various handling test requirements such as steady-state cornering, double lange change, etc. is presented The lead-lag controller is developed with lead and lag compensation. which use the transfer function with cross-over frequency by frequency response method. The proposed driver model is applied to a vehicle model in steady-state and slalom maneuver to verify its effectiveness and validity. The results show that the proposed path control strategy is excellent both in pursuing the desired course and stability of the vehicle.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.1
• /
• pp.139-147
• /
• 2001

In this study a path control scheme of simulation models of various vehicles to evaluate their handling characteristic is developed. Based on the forward target method, path deviation error is estimated and the required steering effort to reduce the error is computed by Ziegler-Nichols PID control rule. Velocity control model is also included in the proposed path control scheme to achieve the desired velocity. The path control scheme is implemented on a full vehicle model to perform ISO test procedures, such as steady state cornering, lane change, and sinusoidal input, etc. Through the simulations of ISO test procedures and comparison with actual tests, effectiveness and validity of the path control model is demonstrated.