• The Mathematical Education
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• v.63 no.3
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• pp.437-450
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• 2024

Self-directed learning in mathematics education is crucial because it enables students to think creatively and critically while continuously improving. The purpose of this study was to examine the mediating effects of class attitude and class satisfaction in mathematics on the relationship between mathematics teacher characteristics and self-directed learning. Furthermore, the study aimed to determine whether these structural relationships differ between male and female student groups. To achieve this, the theoretical model was tested using the 9th-year data (high school 3rd grade) of the Seoul Education Longitudinal Study (SELS) 2010, comprising 2,325 students (1,187 males and 1,138 females). The results revealed that the mediating effects of mathematics class attitude and class satisfaction on the relationship between teacher characteristics in mathematics and high school students' self-directed learning were significant. At this time, the direct effect of mathematics teacher characteristics on selfdirected learning was not significant, indicating that mathematics class attitude and class satisfaction had full mediating effects. Multi-group analysis results showed no significant differences in path coefficients between male and female student groups. Based on the research findings, implications for teacher education were presented to improve high school students' self-directed learning abilities in mathematics education, focusing on the mediating effects of affective factors in the classroom.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.5
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• pp.349-354
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• 2011

Introduction: Mandibular third molar extraction is one of the most common procedures performed in oral and maxillofacial surgery units. Although the overall complication rate is low with most complications being minor, mandibular third molar removal is so common that the population morbidity of complications might be significant. Therefore, efforts to limit intraoperative or postoperative complications might have a significant impact in terms of enhancing the patient outcome. The aims of this study were to identify the position and angulation associated complications after mandibular third molar extractions. Materials and Methods: This study surveyed 568 patients who had a mandibular third molar extracted, showed clinical complications and underwent a radiographic measurement of the available space, depth and spatial relationship. Results: The results obtained were as follows: 1. The complications were a dry socket, nerve injury, root rest, infection, bleeding, hamatoma, and adjacent teeth injury. 2. There were no significant differences between the complication and ramus relationship (available space) of the mandibular third molar. 3. There were no significant differences between the complications and depth of the mandibular third molar. 4. There were no significant differences between the complications and spatial relationship of the mandibular third molar. Conclusion: There were no significant differences in the complication rate, ramus relationship, depth and spatial relationship of the mandibular third molar. This suggests that the position and angulation of the mandibular third molar may not have an impact on the complications. The relationship between the position and angulation of the mandibular third molar, and complications deserves a further study using longitudinal data.

• Korea journal of population studies
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• v.33 no.1
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• pp.103-131
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• 2010

This study observes how the conjugal sharing of the roles such as breadwinning, housework/childcare, and leisure activities affects wives' marital satisfaction, and how the relationships among the considered variables are similar or different across age categories. Two dependent variables, the relationship satisfaction and the marital happiness, are measured and estimated as the concept of the marital satisfaction. Analysed is the Korean Longitudinal Survey of Women and Families 2008 collected by Korean Women's Development Institute. Among women in the ages of 30s-50s, full-time housewives with the breadwinning husbands feel happier with their marriage than the wives in dual career families, and those in dual career families are happier than the breadwinning women with the househusbands. Among the women in their 40s, the highest relationship satisfaction is reported by the those of the dual career families. Wives in their 30s prefer equal division of familywork in explaining the relationship satisfaction, while wives in the age of 40s and 50s show only the effect of reducing wives' portion. The co-spousal leisure activity is consistently significant in its positive relationship with the marital satisfaction across the age categories. There is a general tendency that the marital satisfaction is the highest in the youngest age bracket and the lowest in the oldest. For managing better marriages, individual efforts of both spouses as well as social support are required.

• Korean small business review
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• v.43 no.1
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• pp.85-105
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• 2021

This study verified how R&D investment affects the management performance of SMEs, whether technology innovation mediates this relationship, and whether marketing competency moderates the relationship between technology innovation and management performance. A longitudinal analysis was conducted using data from the corporate panel survey performed by Daegu Technopark every year since 2013. Data from 349 companies in the Daegu-Gyeongbuk region were mainly used, and the size of 30 to 50 employees in the manufacturing industry was a major analysis target company. The results are as below. First, The results showed that R&D investment had a positive effect on management as well as technology innovation, but technology innovation did not affect management performance. Also, technological innovation did not mediate the relationship between R&D investment and management performance. This shows that in the case of small SMEs, even if technological innovation occurs through R&D investment, the technological innovation does not lead to management performance. Also, the relationship between technological innovation and management performance was not changed by marketing capabilities. This shows that technological innovation in small SMEs is not easy to lead to business performance.

• Journal of Korean Home Economics Education Association
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• v.34 no.2
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• pp.77-93
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• 2022

The purpose of this study was to identify the latent profiles according to the core competencies of middle school students and to examine whether the parent-child relationship predicts the latent profiles based on the core competencies for students defined by the Korean Ministry of Education. To achieve the purpose of the study, a total of 6,065 second-year middle school students were analyzed from the fourth year of the Korean Educational Longitudinal Study (KELS 2013), which was conducted by the Korean Educational Development Institute in 2016. The results of latent profile analysis and multinomial logistic regression are as follows. First, three latent profiles (higher competency group (19.54%), middle competency group (49.03%), and lower competency group (31.43%)) were derived according to the core competencies. For all groups, the highest competency was communication ability, and the lowest was creative ability. Second, the variables of the parent-child relationship (i.e., parental academic support, emotional support, and attachment level) were significant in predicting differences among the core competency latent profiles. In particular, the emotional support of parents was found to have the greatest influence on the core competencies of middle school students. This study identified the influence of the parent-child relationship on the development of core competencies. Further, it showed that a good family relationship is important for the holistic development of adolescents.

• Korean Journal of Social Welfare Studies
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• v.44 no.2
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• pp.169-199
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• 2013

This study has a purpose to analyze trajectories of life satisfaction of the elderly after their retirement and how the characteristics of individual, retirement and family relationship have an effect on the life satisfaction. This study has investigated the Korean elderly, who had been retired, using the data from three waves(1st wave(2005)~3rd wave(2009) of the Korean Retirement and Income Panel(KReIS). Data analysis has been used to identify the predictors of the intercept and slope related to the life satisfaction after retirement, focusing the trajectories of the life satisfaction after retirement and individual characteristics, retirement characteristics and family relationship with application of the growth curve model by Amos 20.0. First, the intercept of the life satisfaction after retirement was somewhat below average. Life satisfaction averagely increased little by little from 1st wave to 3rd wave. Second, by conducting the conditional growth curve model, the study revealed that the intercept of the life satisfaction after retirement is high on individual characteristics(sex, educational level, income, health status) and in retirement characteristics(voluntary retirement) and satisfaction with family relationship and married life). Furthermore, health status, voluntary retirement, and satisfaction with family relationship asserted the meaningful variables in the slope of life satisfaction after retirement.

• Safety and Health at Work
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• v.6 no.2
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• pp.90-96
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• 2015

Background: The physical work demands of construction work can be reduced using ergonomic measures. The aim of this study was to evaluate the use of ergonomic measures related to musculoskeletal disorders (MSDs) among construction workers. Methods: A questionnaire was sent at baseline and 2 years later to 1,130 construction workers. We established (1) the proportion of workers reporting an increase in their use of ergonomic measures, (2) the proportion of workers reporting a decrease in MSDs, (3) the relative risk for an increase in the use of ergonomic measures and a decrease in MSDs, and (4) workers' knowledge and opinions about the use of ergonomic measures. Results: At follow-up, response rate was 63% (713/1,130). The proportion of workers using ergonomic measures for vertical transport increased (34%, 144/419, p < 0.01); for measures regarding horizontal transport and the positioning of materials, no change was reported. The proportion of workers reporting shoulder complaints decreased (28%, 176/638, p = 0.02). A relationship between the use of ergonomic measures and MSDs was not found; 83% (581/704) of the workers indicated having sufficient knowledge about ergonomic measures. Lightening the physical load was reported to be the main reason for using them. Conclusion: Only the use of ergonomic measures for vertical transport increased over a 2-year period. No relationship between the use of ergonomic measures and MSDs was found. Strategies aimed at improving the availability of ergonomic equipment complemented with individualized advice and training in using them might be the required next steps to increase the use of ergonomic measures.

• The korean journal of orthodontics
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• v.24 no.3 s.46
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• pp.535-546
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• 1994

The research work has been conducted in order to establish facts on posterior available space in patients with crowding. The relation between crowding and posterior available space was worked out through a cross sectinal study of fifty eight patients showing class I malocclusion. In addition, a longitudinal overlapping study was done by examing twenty patients who had their bicuspid extracted and forty nine patients who did not, at the orthodontic department of dental clinic affiliated in Chosun University. The patients had been examined for three years and eight months on a regular basis, and the study yielded the following conculusion. 1. There was a great difference in posterior available space between patients with serious crowding and those with slight crowding. The former marked 15.2mm of posterior available space and the latter 19.9mm. 2. Posterior crowding index was acquired by joint consideration of the diameter of posterior teeth and posterior available space, and manifested the highest relationship with crowding among measured items. 3. Patients who had their bicuspids extracted exhibited increase in posterior available space of 1.6mm/year and those who did not 1.8mm/year. 4. The absorption of anterior border of ramus turned out to be most deeply related with the increase of posterior available space. 5. Anterior border of ramus was absorbed at the average rate of 0.7mm/year during the period of observation. 6. The extraction of bicuspids had little influnce on the change in posterior available space.

• Geomechanics and Engineering
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• v.22 no.2
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• pp.133-142
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• 2020

The evolution of the mining-induced fracture network formed during longwall top coal caving (LTCC) has a great influence on the gas drainage, roof control, top coal recovery ratio and engineering safety of aquifers. To reveal the evolution of the mining-induced stress and fracture network formed during LTCC, the fracture network in front of the working face was observed by borehole video experiments. A discrete element model was established by the universal discrete element code (UDEC) to explore the local stress distribution. The regression relationship between the fractal dimension of the fracture network and mining stress was established. The results revealed the following: (1) The mining disturbance had the most severe impact on the borehole depth range between approximately 10 m and 25 m. (2) The distribution of fractures was related to the lithology and its integrity. The coal seam was mainly microfractures, which formed a complex fracture network. The hard rock stratum was mainly included longitudinal cracks and separated fissures. (3) Through a numerical simulation, the stress distribution in front of the mining face and the development of the fracturing of the overlying rock were obtained. There was a quadratic relationship between the fractal dimension of the fractures and the mining stress. The results obtained herein will provide a reference for engineering projects under similar geological conditions.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.4
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• pp.573-583
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• 2015

Objectives: This study was carried out to evaluate the effect of noise exposure and aging on changes in hearing threshold level and the relationship between age and noise. Materials: The author selected 274 male shipyard and assembly line workers as the noise exposed group and 582 males not exposed to noise as the general population group. Data were collected from five years of consecutive annual audiometric tests performed from 2008 to 2012. Results: In the general population and noise exposed groups, there was a reverse phenomenon that hearing threshold level for 2009 was lower than that of 2008, which seemed to be due to the learning effect, but from 2010 hearing threshold level increased. In the noise exposed group, the mean hearing threshold level in the left ear was significantly higher than that for right ear. In the general population group, the older was the age, the higher was the hearing threshold level, especially at 4000 Hz. In the general population and noise exposed groups, frequency, age group and noise exposure independently affected hearing threshold level, and there was no relationship between age and noise exposure. Over all frequencies, the change of hearing threshold level was larger in the noise exposed group than in the general population group. In the noise exposed group below thirty years old, the change at 4000 Hz was remarkable. Conclusions: Age and noise exposure seem to affect hearing threshold level independently and contribute to an additive effect on hearing threshold level.