• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.3
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• pp.66-75
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• 2017

Priority disciplines are an important scheme for service systems to differentiate their services for different classes of customers. (N, n)-preemptive priority disciplines enable system engineers to fine-tune the performances of different classes of customers arriving to the system. Due to this virtue of controllability, (N, n)-preemptive priority queueing models can be applied to various types of systems in which the service performances of different classes of customers need to be adjusted for a complex objective. In this paper, we extend the existing (N, n)-preemptive resume and (N, n)-preemptive repeat-identical priority queueing models to the (N, n)-preemptive repeat-different priority queueing model. We derive the queue-length distributions in the M/G/1 queueing model with two classes of customers, under the (N, n)-preemptive repeat-different priority discipline. In order to derive the queue-length distributions, we employ an analysis of the effective service time of a low-priority customer, a delay cycle analysis, and a joint transformation method. We then derive the first and second moments of the queue lengths of high- and low-priority customers. We also present a numerical example for the first and second moments of the queue length of high- and low-priority customers. Through doing this, we show that, under the (N, n)-preemptive repeat-different priority discipline, the first and second moments of customers with high priority are bounded by some upper bounds, regardless of the service characteristics of customers with low priority. This property may help system engineers design such service systems that guarantee the mean and variance of delay for primary users under a certain bounds, when preempted services have to be restarted with another service time resampled from the same service time distribution.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.611-620
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• 2010

The purpose of this study was to explore the structure and content of chemistry teacher's explanations from the perspective of 'persuasion'. Especially, this study was to explore how the argument structure and the conceptual change constructs in chemistry teachers' explanations were established and interacted. Data were collected from chemistryI classes considering the gas unit which includes kinetic theory of gas, Graham's law, Boyle's law, and Charles' law. The classes were vediotaped and transcribed. The transcriptions were analyzed with Toulmin's argument frame and the two constructs of conceptual change model; the conceptual ecology and the status of a conception to interpret the persuasive structure and content of the teacher's explanations. As the results of this study, four explanatory discourses which show various persuasive explanations in chemistry classes. Based on this results, discussion and implications for effective teachers' explanations in chemistry classes were presented.

• Journal of Digital Convergence
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• v.17 no.12
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• pp.67-75
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• 2019

This study was conducted to analyze the effects of mathematics classes using engineering tools on students' mathematics academic achievement and mathematics learning attitude, focusing on the basic figure and drawing sections of the first grade of middle school. Eighty students of first-grade at H Middle School in South Gyeongsang province were divided into two groups, taking a total of six weeks of classes using engineering tools(Algeomath) and traditional tools, and covariate analysis(ANCOVA) was used to analyze students' mathematics academic achievements and changes in mathematical learning attitude. The analysis found that classes using engineering tools were effective in students' mathematics academic achievements and attitude of learning math. Based on the results of the study, the necessity of utilizing various engineering tools in the future secondary school math class and the prospect and implications of the classes were discussed.

• Journal of Korean Elementary Science Education
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• v.39 no.1
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• pp.133-144
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• 2020

The purpose of this study is to identify the effect of Teacher Participation-oriented Education Program (TPEP) for Elementary School Teachers to Improve Class Expertise in Science Classes with a focus on visual attention. The participants were two elementary school teachers in Seoul and taught science subjects. The lesson topic applied to this study were 'Structure and Function of Our Body' in the second semester of fifth grade and 'Volcano and Earthquake' in the second semester of fourth grade. The mobile eye tracker SMI's ETG 2w, which is a binocular tracking system was used in this study. In this study, the actual practice time, participant's visual attention, visual intake time average, and visual intake time average were analyzed by class phase. The results of the study are as follows. First, as a result of analyzing the actual class execution time, the actual class execution time was almost in line with the lesson plan after the TPEP application. Second, visual attention in the areas related to teaching and learning activities was high after applying TPEP. Factors affecting the progress of the class and cognitive burdens were identified quantitatively and objectively through visual attention. Third, as a result of analyzing the visual intake time average of participants, there was a statistically significant difference in all classes. Fourth, as a result of analyzing the visual intake time average of participants, the results were statistically significant in the introduction(video), activity 1, activity 2, and activity 3 stages in the lecture type class. The Teacher Participation-oriented Education Program (TPEP) for Elementary School Teachers to Improve Class Expertise in Science Classes can extend elementary science class expertise such as self-class analysis, eye tracking, linguistic, gesture, and class design beyond traditional class analysis and consulting.

• Human Ecology Research
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• v.55 no.2
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• pp.193-204
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• 2017

This study examines the effect of 5-year-old children's mathematical problem solving ability and their self-esteem based on the Havruta method using math storybooks. The subjects of this study were 40 5-year-old students attending a kindergarten in the Incheon area: 20 students comprised the treatment group and 20 students comprised the control group. An instrument originally created by Ward (1993) but adapted by Hwang (1997) and later modified by Ryu (2003) was used to test the children's mathematical problem solving abilities. A modified version (Kim, 1997) of an instrument developed by Harter and Pike (1984) was used to measure children's self-esteem. Test results were analyzed using SPSS ver. 18.0 for Windows. The findings are as follows. First, the treatment group that had Havruta classes utilizing math story books was found to improve significantly more than the control group in their mathematical problem solving ability. Havruta classes had positive effects on children's mathematical problem solving abilities. Second, there was no significant difference found between the two groups in terms of self-esteem when the children's self-esteem was compared after Havruta classes that utilize math storybooks. It may not be possible to see immediate changes in children's self-esteem because positive parent and teacher feedback had the strongest influence on 5-year-old children's self-esteem, as opposed to self-learning. The results of this study provide meaningful basic data for Havruta classes that focus on questions and discussions through math story books to increase children's mathematical problem solving abilities in the child education field.

• Journal of Digital Convergence
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• v.19 no.12
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• pp.91-102
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• 2021

This study explored the educational effects of the digital citizenship teaching and learning model on middle school science classes. For this purpose, two classes of the third grade of middle school in Gyeonggi-do were selected, and the experimental group(28 students) was taught science classes using digital citizenship learning model, and the control group(28 students) was taught in regular lectures. The measurements used to verify the effects of science classes using the digital citizenship learning model were digital citizenship and empathy tools. The data collected for the effect verification were analyzed by independent sample t-test and ANCOVA. As a result, the experimental group applying the digital citizenship learning model showed higher scores of digital citizenship and empathy than the control group. Therefore, it can be seen that the middle school science class applying the digital citizenship learning model was effective in cultivating the digital citizenship and empathy of middle school students. In future studies, it is necessary to examine the effects of digital citizenship learning model at different school levels and other subjects.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.350-358
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• 2021

The purpose of this study is to analyze the status of rights for online learning of students with developmental disabilities in the COVID-19 situation and suggest plans to promote the rights focusing on parents with children with disabilities. This research conducted the mixed method, which utilizes the survey of 200 parents with children in chungbuk, who have developmental disabilities, and FGI of six parents. The survey analysis shows that 50.5% of the respondents could not support their children due to telecommuting. The most urgent support system for learning assistance was identified as support for assistive personnel. As a result of the analysis of FGI, two categories of "status of online classes in the COVID-19," "improving non-contact learning environment considering the nurturing environment," "diversifying teaching methods such as video classes," "introducing of a contextual assessment," and "enhancing health support." Based on these findings, the study proposed to review legal grounds for online classes for disabled students, expand the dispatch of learning support personnel and prepare plans to promote the online learning environment.

• Journal of the Korean Society for Library and Information Science
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• v.55 no.1
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• pp.541-565
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• 2021

The study is aimed at designing an effective edutech platform based on online remote classes, and clarifying the effect of empathy competence of youths through the operation linked with the empathic reading program focusing on reading. To this end, after constructing the environment for education and drawing a class model based on components of edutech for remote classes on the basis of previous studies and elaborating the empathic reading education program, this study has been conducted for one semester for 107 students in 4 classes in their 1st grade at S middle school, Gyeonggi-do in order to apply them to fields. As a result of the study, the empathy reading program that a remote class model was applied has shown a meaningful difference among groups in cognitive empathy and emotional empathy, and it was found that there was a statistically meaningful difference between the two groups in total scores. Besides, the effect and meaning of adolescents' empathy competence have been verified through the remote empathy reading education and the empirical analysis, and the direction to develop the empathy reading program has been suggested for a solution to settle differences in students' learning due to COVID-19.

• Imaging Science in Dentistry
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• v.52 no.1
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• pp.75-82
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• 2022

Purpose: This cross-sectional study evaluated and categorized the tomographic sagittal root position (SRP) of the maxillary anterior teeth in a Brazilian population. Materials and Methods: Cone-beam computed tomographic scans of 420 maxillary anterior teeth of 70 patients (35 men and 35 women, mean age 25.2±5.9 years) were evaluated. The SRP was classified as class I, II, III, or IV. In class I, the root is positioned against the buccal cortical plate; in class II, the root is centered in the middle of the alveolar housing; in class III, the root is positioned against the palatal cortical plate; and in class IV, at least two-thirds of the root engage both the buccal and palatal cortical plates. Results: In total, 274 teeth (65.2%) were class I, 39 (9.3%) were class II, 3 (0.7%) were class III, and 104 (24.8%) were class IV. The frequency distribution over the teeth groups was different from the overall analysis. Important differences were found in the frequencies of classes I, II, and IV compared to other populations. Sex was not associated with the SRP classes (P=0.307). Age distribution was significantly different over the classes (P=0.004). Conclusion: The findings of this study on the distribution of SRP classes among the Brazilian population compared to other populations demonstrate that the SRP should be analyzed on a case-by-case basis for an accurate treatment plan in the maxillary anterior area.

• Journal of Korean Society on Water Environment
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• v.39 no.1
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• pp.1-8
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• 2023

Monitoring and prediction of water quality are essential for effective river pollution prevention and water quality management. In this study, a multi-classification model was developed to predict chlorophyll-a (Chl-a) level in rivers. A model was developed using CatBoost, a novel ensemble machine learning algorithm. The model was developed using hourly field monitoring data collected from January 1 to December 31, 2015. For model development, chl-a was classified into class 1 (Chl-a≤10 ㎍/L), class 2 (10<Chl-a≤50 ㎍/L), and class 3 (Chl-a>50 ㎍/L), where the number of data used for the model training were 27,192, 11,031, and 511, respectively. The macro averages of precision, recall, and F1-score for the three classes were 0.58, 0.58, and 0.58, respectively, while the weighted averages were 0.89, 0.90, and 0.89, for precision, recall, and F1-score, respectively. The model showed relatively poor performance for class 3 where the number of observations was much smaller compared to the other two classes. The imbalance of data distribution among the three classes was resolved by using the synthetic minority over-sampling technique (SMOTE) algorithm, where the number of data used for model training was evenly distributed as 26,868 for each class. The model performance was improved with the macro averages of precision, rcall, and F1-score of the three classes as 0.58, 0.70, and 0.59, respectively, while the weighted averages were 0.88, 0.84, and 0.86 after SMOTE application.