• The Journal of Engineering Geology
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• v.33 no.3
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• pp.371-388
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• 2023

A stratum with a complex composition and a distributed low-permeability soil layer is difficult to remediate quickly because the soil remediation does not proceed easily. For efficient purification, the permeability should be improved and the soil remediation agent (H₂O₂) should be injected into the contaminated section to make sufficient contact with the TPH (Total petroleum hydrocarbons). This study analyzed a method for crack formation and effective delivery of the soil remediation agent based on pneumatic fracturing, plasma blasting, and vacuum suction (the PPV method) and compared its improvement effect relative to chemical oxidation. A demonstration test confirmed the effective delivery of the soil remediation agent to a site contaminated with TPH. The injection amount and injection time were monitored to calculate the delivery characteristics and the range of influence, and electrical resistivity surveying qualitatively confirmed changes in the underground environment. Permeability tests also evaluated and compared the permeability changes for each method. The amount of soil remediation agent injected was increased by about 4.74 to 7.48 times in the experimental group (PPV method) compared with the control group (chemical oxidation); the PPV method allowed injection rates per unit time (L/min) about 5.00 to 7.54 times quicker than the control method. Electrical resistivity measurements assessed that in the PPV method, the diffusion of H₂O₂2 and other fluids to the surface soil layer reduced the low resistivity change ratio: the horizontal change ratio between the injection well and the extraction well decreased the resistivity by about 1.12 to 2.38 times. Quantitative evaluation of hydraulic conductivity at the end of the test found that the control group had 21.1% of the original hydraulic conductivity and the experimental group retained 81.3% of the initial value, close to the initial permeability coefficient. Calculated radii of influence based on the survey results showed that the results of the PPV method were improved by 220% on average compared with those of the control group.

• Journal of Nutrition and Health
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• v.56 no.3
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• pp.300-314
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• 2023

Purpose: This study sought to predict the reasons for skipping breakfast by adolescents aged 13-18 years using the 7^th Korea National Health and Nutrition Examination Survey (KNHANES). Methods: The participants included 1,024 adolescents. The data were analyzed using a complex-sample t-test, the Rao Scott χ²-test, and the classification and regression tree (CART) algorithm for decision tree analysis with SPSS v. 27.0. The participants were divided into two groups, one regularly eating breakfast and the other skipping it. Results: A total of 579 and 445 study participants were found to be breakfast consumers and breakfast skippers respectively. Breakfast consumers were significantly younger than those who skipped breakfast. In addition, breakfast consumers had a significantly higher frequency of eating dinner, had been taught about nutrition, and had a lower frequency of eating out. The breakfast skippers did so to lose weight. Children who skipped breakfast consumed less energy, carbohydrates, proteins, fats, fiber, cholesterol, vitamin C, vitamin A, calcium, vitamin B1, vitamin B2, phosphorus, sodium, iron, potassium, and niacin than those who consumed breakfast. The best predictor of skipping breakfast was identifying adolescents who sought to control their weight by not eating meals. Other participants who had low and middle-low household incomes, ate dinner 3-4 times a week, were more than 14.5 years old, and ate out once a day showed a higher frequency of skipping breakfast. Conclusion: Based on these results, nutrition education targeted at losing weight correctly and emphasizing the importance of breakfast, especially for adolescents, is required. Moreover, nutrition educators should consider designing and implementing specific action plans to encourage adolescents to improve their breakfast-eating practices by also eating dinner regularly and reducing eating out.

• Journal of the Korean Society of Earth Science Education
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• v.17 no.2
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• pp.123-136
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• 2024

This study examines the performance expectations (PEs) and clarification statements of each PE in the 2022 revised national science and mathematics education standards from a data visualization competency perspective. First, the authors intensively reviewed data visualization literature to define key competencies and developed a framework comprising four main categories: collection and pre-processing skills, technical skills, thinking skills, and interaction skills. Based on the framework, the authors extracted a total of 191 mathematics and 230 science PEs from the 2022 revised science and mathematics education standards (Ministry of Education Ordinance No. 2022-33, Volumes 8 and 9) as the main data set. The analysis process consisted of three steps: first, the authors organized the data (421 PEs) by the four categories of the framework and four grade levels (3-4th, 5-6th, 7-9th, and 10th grade); second, the numbers of PEs in each grade level were standardized by the accomplishing period (1-3 years) of each PE depending on the grade level; lastly, the data set was represented by heatmaps to visualize the relationship between the four categories of visualization competency and four grade levels, and the differences between the competency categories and grade levels were quantitatively analyzed using the Mann-Whitney U test and independent sample Kruskal-Wallis tests. The analysis results revealed that in mathematics, there was no significant difference between the number of PEs by grade. However, on average, the number of PEs categorized in 'thinking skills' was significantly lower than those in the technical skills (p = .002) and interaction skills categories (p = .001). In science, it was observed that as grade level increased, PEs also increased (pairwise comparison: Grades 5-6 vs. 7-9, p = .001; Grades 5-6 vs. Grade 10, p = .029; Grades 3-4 vs. 7-9, p = .022). Particularly, the frequency of PEs in 'thinking skills' was significantly lower than in the other skills (pairwise comparison: technical skills p = .024; collection and pre-processing skills p = .012; interaction skills p = .010). Based on the results, two implications for revising national science and mathematics standards and teacher education were suggested.

• The korean journal of orthodontics
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• v.36 no.5
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• pp.339-348
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• 2006

Objective: With development of the skeletal anchorage system, orthodontic mini-implant (OMI) assisted on masse sliding retraction has become part of general orthodontic treatment. But compared to the emphasis on successful anchorage preparation, the control of anterior teeth axis has not been emphasized enough. Methods: A 3-D finite element Base model of maxillary dental arch and a Lingual tipping model with lingually inclined anterior teeth were constructed. To evaluate factors influencing the axis of anterior teeth when OMI was used as anchorage, models were simulated with 2 mm or 5 mm retraction hooks and/or by the addition of 4 mm of compensating curve (CC) on the main archwire. The stress distribution on the roots and a 25000 times enlarged axis graph were evaluated. Results: Intrusive component of retraction force directed postero-superiorly from the 2 mm height hook did not reduce the lingual tipping of anterior teeth. When hook height was increased to 5 mm, lateral incisor showed crown-labial and root-lingual torque and uncontrolled tipping of the canine was increased.4 mm of CC added to the main archwire also induced crown-labial and root-lingual torque of the lateral incisor but uncontrolled tipping of the canine was decreased. Lingual tipping model showed very similar results compared with the Base model. Conclusion: The results of this study showed that height of the hook and compensating curve on the main archwire can influence the axis of anterior teeth. These data can be used as guidelines for clinical application.

• Clinical and Experimental Pediatrics
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• v.50 no.6
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• pp.531-535
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• 2007

Purpose : Indomethacin treatment is successful in about 90% of patent ductus arteriosus (PDA) in premature infants, but in some, repeated administration or surgical closure is required. The object of the present study is to determine the factors affecting the efficacy of indomethacin treatment and to predict the treatment result. Method : The 29 preterm neonates, admitted to neonatal intensive care unit of Kyunghee university medical center and Eulji university hospital between September 2002 and April 2006 were diagnosed of PDA and treated with indomethacin. The risk factors that might affect the efficacy of treatment were studied retrospectively. Results : The single-administered group was 19 patients out of 29 (65.5%) and among the repeated-administered group, 5 patients (17.2%) had repeated indomethacin administration and the other 5 patients (17.2%) underwent surgery due to reopening of the duct after repeated medical treatment. In repeated-administered group, the diameter of PDA was significantly larger ($3.66{\pm}0.8mm$ vs $2.55{\pm}0.8mm$, P<0.01), especially when larger than 3.5 mm (sensitivity: 70%, specificity: 89%). Also, the mean postnatal age of the first indomethacin administration was significantly delayed in repeated-administered group (19.7 days vs 12.5 days, P<0.05). There were no significant differences in gestational age (32 wk 5 days vs 30 wk 8 days) and in birth weight (1598.9 g vs 1750.5 g). There were no significant differences in associated morbidities. Conclusion : In patients with larger diameter of PDA (>3.5 mm) and older postnatal age (>7 days), the effect of indomethacin was decreased. Therefore in such cases, repeated dose of indomethacin or surgical ligation should be considered earlier.

• Journal of dental hygiene science
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• v.13 no.2
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• pp.165-173
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• 2013

The purpose of this study was to evaluate the surface change after 15% carbamide peroxide home bleaching to various restorative materials (composite resin [CR], resin modified glass ionomer [RMGI] and glass ionomer [GI]) and to observe the effect of surface condition of the materials on re-staining. Three esthetic restorative materials (Filtek Z250, 3M, USA; Fuji II LC, GC, Japan; Fuji II, GC, Japan) were used in this study. Twenty specimens per material group were made and divided into two groups (bleached and control). The specimens were immersed in coffee after applying bleaching agent. The color change and surface roughness were measured before and after bleaching and after immersion in coffee. The data were analyzed with SPSS 18.0. The results were as follows: 1. The color of all experiment groups was significantly changed after bleaching (p<0.05). RMGI was the greatest value of ${\Delta}E^*$ and ${\Delta}L^*$. GI and CR groups were in ordering (p<0.05). The ${\Delta}a^*$ value was decreased GI, RMGI and CR. RMGI was only significantly decreased in ${\Delta}b^*$ value (p<0.05). 2. The surface roughness before and after bleaching was significantly different on CR, RMGI and GI (p<0.05). 3. After staining with coffee, the value of ${\Delta}E^*$ was increased in GI, RMGI and CR, furthermore GI and RMGI showed significant difference in the bleaching groups (p<0.05). The ${\Delta}L^*$ value of GI and RMGI was significantly decreased. 4. The change of surface roughness after staining was not significantly different in all groups (p>0.05). The maintenance of color stability in esthetic restorations is one of the most important properties. Tooth whitening is for the aesthetic. Therefore, dental professionals should notice to patients about re-staining after tooth whitening. They should give an instruction that how to prevent and which kinds of agents could be stained.

• Journal of Korean Dental Hygiene Science
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• v.2 no.2
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• pp.31-39
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• 2019

Background: The purpose of this study was to investigate the effect of self-perception of halitosis on oral health behaviors of college students according to whether they worked in a non-service or service-related job. Methods: A self-reporting questionnaire of 150 university students working in service jobs and 150 university students working in non-service jobs in the metropolitan area was conducted from 26th April to 5th May 2018. The survey tool consisted of 3 general topic areas. There were 5 questions on oral health awareness behavior, 3 questions related to their self-perception of halitosis, and 8 questions on their oral health care practice. All were measured on the Likert 5-point scale. The frequency of their oral health behaviors and their self-perception of halitosis were analyzed according to the subjects' occupation. Pearson's correlation analysis and a linear regression analysis were conducted to confirm the influence of the two. The significance level for the statistical significance test was set to α = 0.05 (two-tailed). Results: In both the service and non-service groups, a coated tongue and food debris were found to influence halitosis(x²=10.95, p=0.027). According to the t-test, taking into account the self-perception of halitosis and oral health behaviors, both were higher in those that had a service job. Self-perception of halitosis and oral health behaviors were found to have a negative correlation(γ=-0.11, p<0.05). As the self-perception of halitosis increased, oral health care practices also increased(Beta=-0.185, p=0.020). Conclusions: Systematic interventions such as oral health programs and health promotion are needed to improve the oral health of service workers.

• Journal of Environmental Impact Assessment
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• v.27 no.2
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• pp.181-193
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• 2018

The present study was conducted to analyze the quality of the habitats of Abies koreana WILS. by using the InVEST model based on the analytic hierarchy process (AHP) technique and to evaluate the economic value by estimating the carbon fixation. Abies koreana WILS., an original biological species of South Korea, may be an essential element in establishing the national biological sovereignty in the future. The subjects of the present study were the national parks in Mt. Halla, Mt. Jiri, and Mt. Sobaek, which are the habitats of Abies koreana WILS. As suggested by previous studies as a limitation of the InVEST model, the utilization of the data from relevant international publications as the input data, due to the lack of the domestic input data, may decrease the accuracy of the modeling. Therefore, the AHP technique was applied for the input data. The modeling was performed with reference to the years of 1980, 1990, and 2000 for the scenario analysis. The result of the modeling showed that the habitat quality was changed most in the national park in Mt. Halla, as the habitat quality score was decreased from 0.96 in 1980 to 0.97 in 1990 and 0.94 in 2000. In the national part of Mt. Sobeak, the habitat quality was changed most in the sub-alpine zone, as the habitat quality score was decreased from 0.98 in 1980 and 0.98 in 1990 to 0.97 in 2000. The habitat quality was best conserved in the national part in Mt. Jiri, as the habitat quality score was 0.98 in 1980, 0.99 in 1990, and 0.99 in 2000. The estimated economic loss by the change of the habitat quality was 19,280,000 USD for Mt. Halla and 8,030,000 USD for Mt. Sobeak. In the present study, the habitat quality of the Abies koreana WILS, the original species of South Korea, was evaluated and the economic value of the ecological services provided by the habitats was estimated quantitatively. The result showed that the ecosystem service model may be used to qualitatively analyze the quality of a habitat located in a specific region and to estimate the economic value quantitatively. The objective evaluation of ecosystem services demonstrated in the present study may be applied to promote sustainable utilization of natural resources and conservation of the ecosystem by predicting the changes that may be caused by external factors including the development of preservation areas.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.3
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• pp.51-63
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• 2011

The purpose of this study is to create a landscape image that considers the selection of techniques that can enhance landscape reproduction in streetscape evaluation using 3 dimensional simulations and to evaluate ways to verify similarities and the psychological changes on the part of users by season. In the comparison of technique, the Low(apply normal map) technique was selected for the natural representation of trees in a near and middle view and the Plane technique was selected for the distant view. As the result of the verification, all indicators of physical similarity were evaluated over 4.50 points and most indicators of psychological similarity were found to have no difference except for indicators of 'disordered orderly' and 'dirty - clean'. According to the results of analyzing the landscape simulation by season, images of 'bright', 'beautiful', and 'static', etc., were evaluated high for the spring streetscape. The images of 'open', 'refresh', and 'animate' appeared high in summer and images of 'warm' and 'dark' were found to be high in fall. On the other hand, all images were evaluated as low except for the 'orderly' image. In the preference of streetscape by season, summer and spring were highly preferred at 5.01 and 4.98 with winter as the lowest at 3.48. As the results of the analysis of preference factor, the spring streetscape was found to be a major influence in preference by 0.540 in 'aesthetics'. In the case of summer, 'order' was found to be high at 0.417 while influences in preference included 'variety' and 'aesthetics' in fall and 'variety', 'aesthetics', and 'order' in winter. A determination of suitable spatial planning using a comparative analysis of various city streets will be enabled through the methods of this study.

• Journal of agricultural medicine and community health
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• v.29 no.1
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• pp.133-145
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• 2004

Objectives: Depression is a major health concern that can be life threatening if not recognized and treated early. However, there is few report on the depressive disorder of Hansen disease patients in Korea. Therefore, the authors executed this study in order to check factors related to a depressive disorder of a Hansen disease patients and compare with factors to reach to a depressive symptoms of ordinary people with studying their life state and the trouble that Hansen disease patients were currently experiencing Method: The authors surveyed depressive symptoms using self-reported questionnaires in 74 Hansen disease patients and 84 controls. The severity of depressive symptoms was measured using Korean Form of Geriatric Depression Scale (KGDS) score. Result: Positive rate of depressive disorders among Hansen disease patients was 70.3% and that the referents was 31.0%. There is significant difference positive rate of depressive disorders between Hansen disease group and the referents in the factors such as gender, age, frequency of going out, familial type, and familial income. Depressive disorder of Hansen disease group was associated with sex, familial income. According to the multiple logistic regression, the odds ratios of the Hansen disease group versus referents, gender, familial income, frequency of going out were significant (p<0.05). Conclusion: Hansen disease patients had statistically significant higher depressive symptom score than the referents. Also, Hansen disease patients who have lower familial income were more likely to have depressive disorders. Therefore, Economical supports and policy are required for the Hansen disease patients.