• The korean journal of orthodontics
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• v.45 no.3
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• pp.130-135
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• 2015

Objective: In our previous study, glass-fiber-reinforced plastics (GFRPs) made from polycarbonate and glass fibers were prepared for esthetic orthodontic wires using pultrusion. These laboratory GFRP wires are more transparent than the commercially available nickel-titanium wire; however, an investigation of the color stability of GFRP during orthodontic treatment is needed. Accordingly, in the present study, the color stability of GFRP was assessed using colorimetry. Methods: Preparation of GFRP esthetic round wires (diameter: 0.45 mm [0.018 inch]) using pultrusion was described previously. Here, to investigate how the diameter of fiber reinforcement affects color stability, GFRPs were prepared by incorporating either $13-{\mu}m$ (GFRP-13) or $7-{\mu}m$ glass (GFRP-7) fibers. The color changes of GFRPs after 24 h, and following 1, 2, and 4 weeks of coffee immersion at $37^{\circ}C$, were measured by colorimetry. We evaluated the color stability of GFRPs by two evaluating units: the color difference (${\Delta}E^*$) and National Bureau of Standards (NBS). Results: After immersion, both GFRPs showed almost no visible color change. According to the colorimetry measurements, the ${\Delta}E^*$ values of GFRP-13 and GFRP-7 were 0.73-1.16, and 0.62-1.10, respectively. In accordance with NBS units, both GFRPs showed "slight" color changes. As a result, there were no significant differences in the ${\Delta}E^*$ values or NBS units for GFRP-13 or GFRP-7. Moreover, for both GFRPs, no significant differences were observed in any of the immersion periods. Conclusions: Our findings suggest that the GFRPs will maintain high color stability during orthodontic treatment, and are an attractive prospect as esthetic orthodontic wires.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.3
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• pp.310-320
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• 2007

Statement of the problem. The fracture of acrylic resin dentures remains an unsolved problem. Therefore, many investigations have been performed and various approaches to strengthening acrylic resin, for example, the reinforcement of heat-cured acrylic resin using glass fibers, have been suggested over the years. But problems such as poor workability, rough surface, poor adhesion of glass fiber resin complex are not solved yet. Purpose. The aim of the present study was to investigate the effect of short glass fibers on the transverse strength of heat-polymerized denture base acrylic resin and roughness of resin complex after abrasion test. Material and methods. To avoid fiber bunching and achieve even fiber distribution, glass fiber bundles were mixed with acrylic resin powder in conventional mixer with a non-cutting blade, to produce the glass fiber($10{\mu}m$ diameter, 3mm length, silane treated) resin composite. Glass fibers were incorporated at 0%, 3%, 6% and 9% by weight. Transverse strength were measured. After abrasion test, surface roughness was evaluated and scanning electron microscope view was taken for clinical application. Results. 1. 6% and 9% incorporation of 3mm glass fibers in the acrylic resin enhanced the transverse strength of the test specimens(p<0.05). 2. Before abrasion test, incorporation of 0%, 3%, 9% glass fiber in the resin showed no dirrerence in roughness statisticaly(p>0.05). 3. After abrasion test, incorporation of 0%, 3%, 6% glass fiber in the resin showed same surface roughness value statistically(p>0.05). 4. In SEM, surface roughness increased as the percentage of the fibers increased. 5. In the areas where glass fiber bunchings are formated, a remarkably high roughness was noticed. Conclusion. 6% and 9% addition of silane-treated short glass fibers into denture base acrylic resin increased transverse strength significantly. Before and after abrasion test, incorporation of 0%, 3%, 6% glass fiber in the resin showed same surface roughness value statistically.

• Journal of the Korean GEO-environmental Society
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• v.17 no.8
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• pp.5-15
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• 2016

As the increase of domestic sewage treatment plant and reinforcement of the standard of effluent water quality continues, the volumes of sewage sludge are consistently increasing. Existing treatment of sewage sludge, such as incineration and ocean dumping has been prohibited because of air pollution and prohibitions towards ocean dumping, and in turn, recycling and energy recovery from waste methods have being studied recently. However, the lack of technical level and systematic analyses of application technique are problems, that future analysis of such relative technique would be required. The present study has been investigated as follows, management technique of sludge, patent on refuse-derived fuel and increase biogas production and utilizable technology, trend of research paper. Furthermore, research development from five developed nations (Korea, Japan, China, United States, and United Kingdom), domestic and foreign have been investigated and analyzed by section. In this study, the future technical field which is required for effective management of sludge has been suggested.

• Journal of the Korean GEO-environmental Society
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• v.11 no.3
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• pp.53-62
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• 2010

In the early 1990s, it was first introduced the soil nailing method for the slope stability and ground excavation and widely used as method of reinforcement. Also the application of soil nailing has been improved and developed. Most recently used for grout soil nailing greatly improve the methods and techniques for self-improvement techniques are classified as soil nailing. As the representative for the grout pressure method to improve the join method pressure grouting and improved method for the self-drilled soil nailing, removable soil nailing, extension grout method. Three dimensional finite difference analysis was used to evaluate characteristics of pull-out behavior of extension grout method. In this paper, it was described a characteristics of pull-out behavior of soil nailing with extension grout method through the result of numerical method.

• Journal of Korean Academy of Rural Health Nursing
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• v.14 no.2
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• pp.23-29
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• 2019

Purpose: This study was done to identify the cultural capacity of college nursing students and the relationship of intercultural communication. Methods: The participants were 200 students in colleges of nursing from 6 universities in C city, who understood the purpose of the study and agreed to participate. Collected data were analyzed with t-test, ANOVA, correlation analysis, and stepwise regression analysis using SPSS/WIN 22.0. Results: Cultural sensitivities in this study (r=.372, p<.001), cultural knowledge (r=.399, p=.001), cultural awareness (r=.547, p<.001), and cultural technology (r=.550, p<.001) each showed a statistically significant correlation with intercultural communication skills. Conclusion: The results of this study show that reinforcement of the cultural and intercultural communication ability of college nursing students, in-depth exploration of the cultural area and religious inspection, cultural and professional backgrounds, assessment and consideration of cultural characteristics, nursing diagnosis, and health appropriate to the cultural background. It is suggested that education such as service provision should be conducted systematically.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.3
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• pp.322-327
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• 2007

Researchers in the field of psychology used Electroencephalographic (EEG) to record activities of human brain lot many years. As technology develope, neural basis of functional areas of emotion processing is revealed gradually. So we measure fundamental areas of human brain that controls emotion of human by using EEG. Hands gestures such as shaking and head gesture such as nodding are often used as human body languages for communication with each other, and their recognition is important that it is a useful communication medium between human and computers. Research methods about gesture recognition are used of computer vision. Many researchers study emotion recognition method which uses one of physiological signals and gestures in the existing research. In this paper, we use together physiological signals and gestures for emotion recognition of human. And we select the driver emotion as a specific target. The experimental result shows that using of both physiological signals and gestures gets high recognition rates better than using physiological signals or gestures. Both physiological signals and gestures use Interactive Feature Selection(IFS) for the feature selection whose method is based on a reinforcement learning.

• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.35-44
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• 2020

Design techniques for the deep mixing method, one of the soft ground improvement methods, include two ways to interpret the ground as composite ground and pile ground. However, since comparative studies on these two approaches are insufficient, it is difficult to clearly define the analysis criteria in the design. In this study, two-dimensional and three-dimensional analyses have been performed with different conditions. The three conditions, the embankment height, depth of soft ground, and replacement ratio of reinforcement zones were varied and the analysis was performed on the basis of the assumption of composite ground and pile ground for each condition. As a result, the minimum depth of improvement in the two-dimensional analysis was deeper by 6.85~9.08% than in the three-dimensional analysis. The pile ground analysis showed that the depth of improvement was deeper by 12.22~14.45% than the composite ground analysis. Based on these results, it is concluded that for more accurate design, three-dimensional analysis should be performed rather than two-dimensional analysis. also, it is judged that necessary to analyze the ground as composite ground for economical design, and as the pile ground analysis for stable design.

• Journal of the Korean Geotechnical Society
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• v.29 no.11
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• pp.107-118
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• 2013

Geosynthetic reinforced soil (GRS) walls have been increasingly applied recently due to its numerous geotechnical engineering applications. However failure occurs in some cases of constructed GRS walls. These GRS wall failures are mostly due to the unpredictable characteristics of intensive rainfall. Hence, the need for new and innovative ideas for rehabilitation methods has been getting attention. This paper introduces a case study for the design and restoration method of collapsed GRS wall using Limit equilibrium and Numerical Analyses. Restoration method includes: (1) soil nailing without backfill excavation and (2) reconstruction with GRS wall after collapsed backfill excavation. Analyses results show minimal horizontal displacements and shear strain on the reinforced concrete facing for the restoration case with soil nailing. On the other hand, horizontal displacements are developed in the middle of the mortar block facing and shear strains are developed at the bottom facing with spiral curves for the reconstructed GRS wall after collapsed backfill excavation. Therefore, the collapsed GRS wall was restored with the soil nailing without backfill excavation and its construction procedures are discussed in this paper.

• Journal of the Korean Geotechnical Society
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• v.33 no.6
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• pp.17-25
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• 2017

In this research, post grouting methods were applied on PHC piles, and static load tests were conducted to confirm the effect of post grouting on bearing capacity enhancement of PHC piles. Grouting pressures of 1.9 MPa and 3.5 MPa were applied, and bearing capacities of grouted piles were compared with that of non-grouted pile. From the static load test results, the bearing capacities of grouted piles were about 3 times higher than that of non-grouted pile. In addition, the design efficiency (allowable bearing capacity/nominal bearing capacity) increased from 32% to 97% after post grouting, and the axial stiffness of piles also increased by about 1.3 times per grouting pressure.

• Journal of Families and Better Life
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• v.33 no.2
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• pp.119-134
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• 2015

The purpose of the study is to explore how parenting attitudes, ego resilience, and care affects adolescents' adjustment to school so as to provide a necessary basic guideline needed to seek various intervention methods. To achieve this end, the study referred to the 2014 Annual Report of the Korean Children and Youth Panel Survey. By using both SPSS 19.0 and AMOS 19.0, the study yielded the following results. First, the study showed that parenting attitudes, ego resilience, care, and school adjustment all have a positive correlation. Second, by conducting path analysis in order to verify the mediating effect of ego resilience and care with regards to the relationship between parenting attitudes and school adjustment, the direct influence that parenting attitudes had on school adaptation was shown to be relevant. Third, adolescents' ego resilience and care have a partial mediating effect on the relationship between parenting attitudes and school adaptation. Therefore, together with intervention in actual school settings, assessing various factors that would aid the recovery of adolescents' characters and pursuing a positive reinforcement of character by finding protective factors would enable this study to be used as a basic guideline that would prevent adolescents' maladjustment to school and social deviance as well as aid the growth of their characters.