• Journal of Environmental Science International
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• v.22 no.2
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• pp.139-149
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• 2013

Anthropogenic increases in greenhouse gas concentrations, primarily through radiative forcing from carbon dioxide, continue to challenge earth's climate. This study quantified $CO_2$ storage and uptake by dominant forest types and age classes in the middle region of Korea. In addition, the role of forest landscapes in reducing atmospheric $CO_2$ against $CO_2$ emissions based on energy consumption was evaluated. Mean $CO_2$ storage and uptake per unit area by woody plants for three forest types and four age classes were estimated applying regression equations derived to quantify $CO_2$ storage and uptake per tree; and computations per soil unit area were also performed. Total $CO_2$ storage and uptake by forest landscapes were estimated by extrapolating $CO_2$ storage and uptake per unit area. Results indicated mean $CO_2$ storage per unit area by woody plants and soils was higher in older age classes for the same forest types, and higher in broadleaved than coniferous forests for the same age classes, with the exception of age class II (11-20 years). $CO_2$ storage by broadleaved forests of age class V (41-50 years) averaged 662.0 t/ha (US$331.0 hundred/ha), highest for all forest types and age classes evaluated. Overall, an increased mean $CO_2$ uptake per unit area by woody plants was evident for older age classes for the same forest types. However, decreased $CO_2$ uptake by broadleaved forests at age class V was observed, compared to classes III and IV with an average of 27.9 t/ha/yr (US$14.0 hundred/ha/yr). Total $CO_2$ storage by woody plants and soils in the study area was equivalent to 3.4 times the annual $CO_2$ emissions, and woody plants annually offset the $CO_2$ emissions by 17.7%. The important roles of plants and soils were associated with 39.1% of total forest area in South Korea, and $CO_2$ emissions comprised 62.2% of the total population. Therefore, development of forest lands may change $CO_2$ sinks into sources. Forest landscape management strategies were explored to maintain or improve forest roles in reducing atmospheric $CO_2$ levels.

• Journal of Nutrition and Health
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• v.6 no.2
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• pp.35-43
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• 1973

This study is concerned with the nutritional status of the packed lunch boxes which are brought by the junior high school students in Capital City of Seoul. Four hundred and eights students of the 8 school districts in Seoul had been randomly selected as subjects. The contained nutrients in the packed lunch were analysed by the Food Composition Table. To observe the influence of home economical status and mother's educational level on the nutrient concents of packed lunches, the chosen subjects were classified into three large groupings, which are upper, middle and low classes respectively. In addition, comparison between the Recommended Daily Allowanced for Korean people-13 to 15 age group-and the contained nutrients in the lunch boxed had been conducted. T-test was applied to clarify the significance of the differences between each group both economical and educational level. 1. The averaged rations between the Recommended Daily Allowances and the contained nutrients in the lunches stand: Calorie 59.7% (566 Cal.) protein 53.1% (18g), animal protein 48.6% (5g), fat 39.8% (5g), calcium 371.% (0.1g), ferret 66.4% (2.9g) Vitamin A 642 1.U. (31.3%), Vitamin $B_1$ 70.2% (0.3mg), Vitamin $B_2$ 41.4% (0.2g), Niacin 77.0%(4mg), Vitamin C 51.9% (13mg). All of the nctrients fall far behind the Recommended Daily, Allowances for 13 to 15 age group. 2. Home economical status brings influence on the kinds of foods which could been. Protein, animal protein, fat, Vitamin $B_2$, Vitamin C showed significance of diffierences between the upper and middle classes. Between the middle and low classes, Protein, animal protein, fat, calcium and Vitamin C showed significance of difference. And finally, between the upper and low classes, protein, fat, calcium, ferret, Vitamin $B_2$ and Vitamin C showed a great significance. 3. Regardless to the living conditions of the subject students, all the nutrients of the lunches packed by the mothers in the entire educational levels did not reach the Recommended Daily Allowances. Protein, animal protein, fat, ferret, Vitamin A, and Niacin showed the significance of the differences between the upper and middle classes. On the other hand, calorie, animal protein, fat, Vitamin A and Vitamin C showed the significance between the middle and low classes. Between the upper and the low classes, protein, animal protein, fat, and ferret showed significance. 4. The mairdish-ice of the lunch boxes supplied calorie, protein, Vitamin $B_1$, Vitamin $B_2$ and Niacin which stand at 83.8%, 56.1%, 52.5%, and 54.8% respectivly when compared with the whole nutritional contents. 5. The side-dishes of the packed lunch lack in variety of cooking methods. One interesting fact is that entire subject students are very favorable to the food cooked with every kind of grains.

• Survey Research
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• v.10 no.3
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• pp.37-58
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• 2009

The purpose of this study were to identify the subgroups (i.e., latent classes) depending on early adolescents' change patterns in aggression and to test the effects of individual-background variables on determining the latent classes. For these goals, we applied Nagin's(1999) semi-parametric group-based approach to the Korean Youth Panel Study. Results showed that four latent classes were identified, which could be defined based on the patterns as low-level group, increasing group, intermediate-level group, and high-level group. By adding gender, self-control, parent attachment, teacher attachment, and the number of delinquent friends to the unconditional latent class model, we tested the effects of the variables on the latent classes. Multinomial logit analysis showed that gender, self-control, teacher attachment, and the number of delinquent friends were significant determinants of the latent classes. Findings from this study suggest the need to consider heterogeneity in the study of early adolescents' aggression to facilitate more refined targeting of intervention program.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.4
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• pp.92-103
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• 2017

As a professional occupation, landscape education focuses on fostering professional human resources and is one of the major axes of the landscape industry. In this study, a survey of landscape students on their learning and pedagogics was conducted with the aim to present basic information for the improvement of teaching on landscape construction. A total of 348 people answered 14 questions in the category of the impression of landscape construction classes included in the questionnaire. The results showed that the students found landscape construction classes academically important and recognized the necessity for completing these classes, but they were not satisfied with the learning environments and pedagogics used in these classes. They found what they learned not readily applicable to actual practice and saw these classes as part of their preparations for the landscape engineer qualification test. Their demands in relation to the classes included field practice-oriented teaching and participation in various programs for field practice, which highlights the necessity for human resource management-oriented classes that cover planning, design, construction, and management. Challenges in relation to field practice included the provision of environment, for example offering a variety of opportunities and improving treatment in practice. This study has significance in that it analyzed the views of students and discussed directions for future improvement since there is a lack of studies and discussions about education in the field of landscape construction. This study also has a limitation that only four-year universities were included in the study. Comprehensive studies including investigating junior college and graduate school curricula and case studies of landscape construction curricula overseas are needed in the future.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.107-115
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• 2023

High turbidity in source water can have adverse effects on water treatment plant operations and aquatic ecosystems, necessitating turbidity management. Consequently, research aimed at predicting river turbidity continues. This study developed a multi-class classification model for prediction of turbidity using LightGBM (Light Gradient Boosting Machine), a representative ensemble machine learning algorithm. The model utilized data that was classified into four classes ranging from 1 to 4 based on turbidity, from low to high. The number of input data points used for analysis varied among classes, with 945, 763, 95, and 25 data points for classes 1 to 4, respectively. The developed model exhibited precisions of 0.85, 0.71, 0.26, and 0.30, as well as recalls of 0.82, 0.76, 0.19, and 0.60 for classes 1 to 4, respectively. The model tended to perform less effectively in the minority classes due to the limited data available for these classes. To address data imbalance, the SMOTE (Synthetic Minority Over-sampling Technique) algorithm was applied, resulting in improved model performance. For classes 1 to 4, the Precision and Recall of the improved model were 0.88, 0.71, 0.26, 0.25 and 0.79, 0.76, 0.38, 0.60, respectively. This demonstrated that alleviating data imbalance led to a significant enhancement in Recall of the model. Furthermore, to analyze the impact of differences in input data composition addressing the input data imbalance, input data was constructed with various ratios for each class, and the model performances were compared. The results indicate that an appropriate composition ratio for model input data improves the performance of the machine learning model.

• Journal of the Korean Society of Earth Science Education
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• v.7 no.1
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• pp.34-42
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• 2014

The purpose of this study was to examine the effects on the effects of science lessons using six thinking hats techniques on creativity and science academic achievement. To verify the research problem, the subject of this study was fourth-grade students selected from four classes of an elementary school located in Busan. For ten weeks, the experimental group of 40 students was taught using the six thinking hats techniques. The comparative group also of 40 students, was taught in normal classes which used a Text-book. Children were given a creativity test and academic achievement test in science to measure the effects on six thinking hats techniques. Likert scales were used to gather students feedbacks on creativity and science academic achievement. Through these procedures, the following results were obtained: First, the six thinking hats techniques had a more effect on creativity than the normal classes, where a text-book was used. Second, the six thinking hats techniques could be seen to be effective in improving the student's academic achievements in science than the normal classes which used a Text-book. Third, the result of the student recognition investigation, we could know that the students showed lots of interest in the science lessons using six thinking hats techniques, and they were able to understand the scientific theories. As a result, the elementary science class with six thinking hats techniques had the effects of developing creativity and science academic achievement. It means the science class with six thinking hats techniques has potential possibilities and value to develop creativity and science academic achievement.

• Hwankyungkyoyuk
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• v.19 no.2 s.30
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• pp.147-158
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• 2006

The purpose of this study is to closely examine the changes of food and drink waste amounts, and student's environmental literacy. By using creative methods, discretional activity classes, and programs to dispose of food and drink waste from students schoolmeals, and at the same time conduct and teach environmental education classes. To achieve this, students were given ten class lessons in creative discretional activities. Students were given flowerpots containing earthworms and were instructed to raise them, using food and drink waste from school meals. Four classes who were participating in project were examined for changes from March to July 2005. As a result the environmental education classes through creative discretional activities didn't have any significant influence on the students environmental literacy. However it did make a difference to the student's in-terms of their ecological knowledge. The project using earthworms to dispose of food and waste drink showed a decrease of 15% of the amount of waste food and drink from school meals. Moreover student's environmental literacy had been significantly influenced about environmental sensibility, value and causes. Through this study I found that the project using earthworms to dispose of waste food and drink, and creative discretional activities as a lesson decreased the amount of food and drink waste at the school, and the changes to students concerns and understanding about environmental sensibility, value and the various causes of waste food and drink.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.29-36
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• 2012

In this study, frequently passing vehicles with two, three, four, and five axles were chosen through traffic volume analysis in Kyung-In Expressway in order to analyze how the road roughness and vehicle speed affect on the dynamic loads for roads in various vehicle classes. Dynamic loads according to chosen vehicles are estimated by TruckSim program. Dynamic load amplification factor is ratio between dynamic and static loads, and it is also determined for each vehicle classes. From the result of dynamic loads estimated by the dynamic load amplification factor, it is shown that for three-axles vehicle, when IRI is 3.5 and vehicle speed is 100km/hr, asphalt pavements receive additional 36% of static loads in maximum. The analysis of the amplification factor according to each vehicle classes also indicates that the amplification factor increases as the distance between the axles becomes smaller and each axle receives more loads.

• Journal of The Korean Association For Science Education
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• v.22 no.3
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• pp.499-507
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• 2002

In this study, students' perceptions on small group activities in science classes were investigated. The relationships among students' values of and attitudes toward small group activities, gender, prior achievement level, and personality were also studied, Subjects were 226 students from four middle schools in which group activities were frequently used in science classes. In their classes, groups were mainly formed by teacher on the basis of grade and student number, or by drawing lots. Many students were dissatisfied with the grouping methods, preferred to make a group based on their friendship, and hoped that there would be different levels of knowledge among the members. Regardless of their gender or prior achievement level, students perceived positively on small group activities. Students with higher agreeableness and extraversion had higher values of and positive attitudes toward small group activities. Among five personality variables studied, agreeableness was the only one that significantly explained both values of and attitudes toward small group activities.

• 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.