• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.4
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• pp.199-208
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• 2021

Purpose: The purpose of this study was to compare and evaluate the masking ability of three types of high translucent zirconia according to the various thicknesses and backgrounds. Materials and Methods: Using three types of high-translucency zirconia (Ceramill zolid fx white, Ceramill zolid ht+ white, Ceramill zolid ht+ preshade A2), 10 cylindrical specimens were fabricated in 10mm diameter and each with four thicknesses (0.6 mm, 1.0 mm, 1.5 mm, 2.0 mm), respectively by CAD/CAM method. The background was 10 mm in diameter and 10 mm in thickness. A1, A2, A3 flowable resin backgrounds, blue-colored core resin background, and Ni-Cr alloy background were prepared, and black, white backgrounds provided by the spectrophotometer manufacturer (x-rite, Koblach, Austria) were used. zirconia specimens and the background specimen were stacked to measure L, a^*, b^* with Spectrophotometer (Color i5, x-rite, Koblach, Austria) and the ΔE value with the other background is calculated. The Calculated mean ΔE values were compared based on perceptibility threshold 1.0 and acceptability threshold 3.7. Nonparametric tests such as Kruskal-Wallis test were performed to verify statistical significance (α = 0.05). Results: There was a significant difference in the mean ΔE value according to the zirconia type, background and thickness change (P = 0.000). Conclusion: According to the results of this study, the pre-colored high-translucent zirconia can obtain the desired zirconia shade when it is restored on teeth, composite resins, and abutments except for the blue resin core.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.1
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• pp.45-56
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• 2022

The purpose of this study is to evaluate changes of occlusion following the placement of preformed metal crown in the permanent first molar affected by severe caries or hypomineralization. The study was conducted on 24 patients who met the criteria among the patients with occlusion in the permanent first molar reaching the occlusal plane. Restorative treatment was performed on one first molar using preformed metal crown. Before treatment, immediately after treatment, after 4 weeks, and after 8 weeks, the T-scan III was used for measuring distribution of bite force at the maximum intercuspal position, and overbite was measured with digital vernier calipers and change of dental midline was surveyed. After 8 weeks, questionnaires survey was conducted. In most cases, immediately after treatment, the distribution of bite force between the restored side and non-restored side of arch was reversed compared to before treatment, and the overbite was decreased. However, after 4 weeks, bite force of the left and right side was balanced and the distribution of bite force on the restored and non-restored permanent first molars had similar values. Also, the changed overbite and midline were returned to pre-treatment status and there was no significant temporomandibular joint and masticatory discomfort after treatment. In this study, it was confirmed that spontaneous occlusal equilibrium was achieved one month after the placement of preformed metal crown.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.1
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• pp.104-112
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• 2023

A 3D-printed resin crown is a novel option for esthetic crown restoration for primary teeth, which are typically bonded with resin cement. The purpose of this study was to evaluate the bonding ability of a 3D printing resin and compare it with other indirect resin materials for crown fabrication. The shear bond strengths of two 3D printing resin materials, Graphy (GP) and NextDent (NXT), and two indirect resin materials, VIPI Block (VIPI) and MAZIC Duro (MZ), were compared in the study. For all materials, the shear bond strength at the interface between the surface of the resin material and resin cement was measured. The mean shear bond strength values of GP, NXT, MZ, and VIPI were 23.29 ± 3.88, 26.14 ± 4.67, 25.41 ± 4.03, and 18.79 ± 4.26 MPa, respectively. There was no significant difference among the SBSs of GP, NXT and MZ except for VIPI. The result of this study indicates that the 3D printing resin meets the essential requirement for clinical use by showing clinically adequate bond strength.

• Journal of the korean academy of Pediatric Dentistry
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• v.50 no.4
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• pp.409-420
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• 2023

The purpose of this study is to analyze trends in the prevalence of dental caries and demand for dental caries treatment among children under 14 years old using Health Insurance Review and Assessment data. The analysis was conducted using treatment records from a random sample of approximately 1 million pediatric patients from a population that included all children and adolescents for each year from 2011 to 2020. In this study, the number of children diagnosed with K02 dental caries and the number of children receiving dental caries treatment across all ages have increased. However, the number of children aged 10 to 14 who received pulp treatment or extraction has decreased. In the National Survey of Children's Oral Health, the decay-missing-filled teeth index for 5- and 12-year-olds has stagnated or increased slightly, but the percentage of the population with active dental caries has decreased. Accessibility and local environments for dental caries treatment have generally improved compared to the past, but preventive dental care has stagnated over the past decade. Therefore, it is necessary to evaluate the effectiveness of oral health programs implemented in Korea to promote and prevent dental caries among children.

• Journal of the Korean Institute of Rural Architecture
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• v.1 no.2
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• pp.63-73
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• 1999

The study is focused on making space of the abolished primary school for college dormitory in rural area which has regional type nearby city. We, firstly, analysed regional conditions and then surveyed various data for space conditions of dormitory. By surveying exterior space and interior renovation, and analysing the actual conditions of dormitory, we propose design factors and model of using facilities of the abolished primary school. So, the purpose of it is to suggest making space and a model of dormitory utilization of abolished school in regional type nearby city. It is a spacial case of re-using facilities of abolished school in rural area, but we expect that abolished school make an offer another type of using facilities.

• Korean Journal of Child Studies
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• v.28 no.3
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• pp.101-113
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• 2007

The present study investigated the print richness of early childhood classrooms and examined differences in classroom literacy environment by teacher demographics. The 117 participants were teachers of kindergartens and daycare centers. They responded to a 33-item questionnaire constructed by Wolfersberger et al.(2004). Questionnaire categories included literacy items pertaining to classroom environment and literacy items pertaining to teacher-student interactions. Major findings were that the classroom literacy environment was usually satisfactory. The age and career of teachers was the predictor of the classroom literacy environment, especially 'providing the classroom with literacy tools' and 'arranging literacy tools in the classroom space'.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.12
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• pp.1035-1042
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• 2003

As the desire for a better condition in classroom increases, the distribution rate of warming and cooling conditioners increases. But it is known that according to the way by which the equipments put and are operated the comfortableness felt by persons who are in classroom can make a difference. Therefore, proper equipments in accordance with the size of classroom should be considered as well as operational methods when ceiling warming and cooling conditioners put. This study makes conclusions as follows through a simulation to get improvements in accordance with the size of classroom and to improve the heating performance of ceiling warming and cooling conditioners in classroom.

• Journal of the Korean Institute of Rural Architecture
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• v.15 no.4
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• pp.25-34
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• 2013

The purpose of this study is to clarify the actual condition of the plan of middle schools in the rural area. Recently, many middle schools are remodeling the buildings and facilities based on the department system. This study, through analyzing on 3 remodeling cases of middle school in the rural area. This article discuses about the basic characteristics of the plan composition and the education programs of 3 middle schools. This study is showing the variation before and after remodeling and space organization types. The results of this study are summarized as follows; 1) Most of them take horizontal zoning system in the department classrooms. 2) Consideration is given to the space of homebas. 3) In the short term, if there is not enough classroom space utilization ratio should be adjusted in the classroom.

• Journal of the Korean Institute of Rural Architecture
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• v.13 no.2
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• pp.47-54
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• 2011

According to the master plan of the Ministry of Education, Science and Technology, departmentalized class system will be extended to all general middle & high schools by 2014 with the exception only of those having less than 6 classes located in small cities in rural areas. Under departmentalized class system, according to class timetable, students need to move from classroom to another classroom and areas where homebases, lounges, media spaces, rest places, and etc. This study has been undertaken to provide architectural data required in planning for student & learning support space for schools operating departmentalized class system, by investigating and analyzing cases in use at schools operating the system in Chungbuk area. As departmentalized class system is increasingly introduced, student & learning support space should be understood newly as spaces indispensable for students.

• Journal of the Korean Institute of Rural Architecture
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• v.15 no.2
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• pp.33-40
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• 2013

The purpose of this study is to clarify the actual condition of the plan of high schools in the rural area. Recently, many high schools are remodeling the buildings and facilities based on the departmentalized classroom system. This study, through analyzing on 2 remodeling cases of small high schools in the rural area of gyeongnam. This article discuses about the basic characteristics of the plan composition and the education programs of 2 small high schools. This study is showing the variation before and after remodeling and space organization types. The results of this study are summarized as follows; 1) Most of them take horizontal zoning system in the department classrooms. 2) Number and area of teachers' laboratory ware increased in most of floors. 3) Sample schools took much more spaces of homebase than before. 4) Consideration is given to the main subject spaces before the other subject spaces.