• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.428-446
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• 1997

Restorative procedures can lead to weakening tooth due to reduction and alteration of tooth structure. It is essential to prevent fractures to conserve tooth. The resistance to fracture of the restored tooth may be influenced by many factors, among these are the cavity dimension and the physical properties of the restorative material. The placement of direct composite resin restorations has generally been found to have a strengthening effect on the prepared teeth. It is the purpose of this investigation to study the relationship between the cavity isthmus and the fracture resistance of a tooth in composite resin restorations. In this study, MO cavity was prepared on maxillary first premolar. Three dimensional finite element models were made by serial photographic method and isthmus(1/4, 1/3, 1/2 of intercuspal distance) were varied. Two types of model(B and R model) were developed. B model was assumed perfect bonding between the restoration and cavity wall and R model was left unfilled. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as follows : 1. Displacement of buccal cusp in R model occurred and increased as widening of the cavity, and displacement in B model was little and not influenced by cavity width. 2. There was a significant decrease of stress resulting in increase of fracture resistance in B model when compared with R model. 3. With the increase of the isthmus width, B model showed no change in the stress and strain. In R model, the stress and strain increased both in the area of buccal-pulpal line angle and the buccal side of marginal ridge, therefore the possibility of crack increased. 4. The stress and strain were distributed evenly on the tooth in B model, but in R model, were concentrated on the buccal side of the distal marginal ridge and buccal-pulpal line angle, therefore the possibility of fracture increased.

• Journal of Science Education
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• v.41 no.1
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• pp.111-134
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• 2017

The purpose of this study was to develop 'Silver Care Expert' STEAM Program for the elementary students and investigate the effects of the program on creative thinking activity, scientific attitude and leadership. Participants were 110 elementary school students. Before and after the program, the participants were asked to take the test about future time perspective, career awareness and scientific attitude. The major results of this study were as follows. First, the total score of experimental group's future time perspective and all 2 sub-domains was significantly improved than those of comparative group(p<.05). Second, total score of experimental groups' career awareness and all 4 sub-domains were significantly increased than those of comparative group after the STEAM program(p<.05). Third, the total score of experimental groups' scientific attitude and all 7 sub-domains were significantly improved than those of comparative group(p<.05). Fourth, according to students' post-program opinions, experimental group students showed very positive perception like that science class was very interesting and they became interested in science and technology. In conclusion, 'Silver Care Expert' STEAM Program was very effective to improve elementary students' future time perspective, career awareness, scientific attitudes.

• YAKHAK HOEJI
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• v.58 no.6
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• pp.397-404
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• 2014

The Ministry of Health and Welfare proposed the "undergraduate program specializing in pharmaceutical industry" in 2013, as part of its roadmap to assist domestic pharmaceutical companies to become the top-tier pharma companies in near future and provide skilled personnel tailored for pharmaceutical industry. However, it is not clear whether this "undergraduate program" meets the needs of pharmaceutical industry, especially when the number of pharmacy students increased from 1,200 to 1,700 per year since 2009. The purpose of this paper is to identify which educational background is preferred by pharmaceutical companies, by surveying the CEOs of domestic pharmaceutical companies and referring to recruitment advertisements shown in medical newspapers, specified by the fields within the companies. Two independent reviewers referred to recruitment session in Yakup newspaper and Dailypharm from May 2012 until January 2014, focusing on recruitments from pharmaceutical companies targeting bachelors' degree holders with no prior experience. 749 recruitments were observed during the study period, more than 90% of which were provided by domestic pharmaceutical companies, and regardless of the companies being domestic or multinational, pharmaceutical companies' preference for pharmacists was remarkable (44.3% for domestic and 65.8% for multinational), and the preference was especially high in the fields such as Medical, R&D, Market Access (regulatory affair/pricing and reimbursement), Business Development, and Marketing. Survey results showed that the need of establishing the undergraduate program specializing in pharmaceutical industry is mixed, suggesting that although there is need for the educating personnel targeting pharmaceutical industry, the undergraduate program would not be an answer due to current PEET system. Our study concludes that in the example of pharmaceutical companies' recruitments shown in medical newspapers, pharmaceutical companies prefer pharmacy major in almost all fields of the pharmaceutical companies, yet the pharmaceutical companies still perceive the gap between current bachelor's degree holders(including pharmacy majors) and the ideal personnel required for advancing to the "top-class" pharmaceutical companies.

• Journal of Chest Surgery
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• v.29 no.2
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• pp.171-176
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• 1996

From March, 1983 to June, 1994, twenty-two patients underwent coronary artery and combined operations. The ages of the patients ranged from 42 years to 72 years (mean 60.4$\pm$8.2 years). There were 17 male and 5 female patients. The left ventricular (LV) ejection fraction ranged from 25% to 65% (mean 46.9$\pm$14.2%). Nine patients had mechanical complication of myocardial infarction (MI), of which 5 were LV aneurysm, 3 ventricular septal defect and 1 mitral regurgitation. Nine patients had rheumatic valvular heart disease of whom 7 with aortic valve disease and 2 with mitral valve disease. Two other patients had left atrial thrombi, only one with atrial septal defect a d another with aneurysm of ascending aorta. An average of 2.1$\pm$1.0 bypasses was done, ranging from one to four. There were 3 postoperative complications; 2 perioperative MI and 1 leg wound infection. Among complicated patients, mortality was 1 patient (4.5%) due to low cardiac output syndrome after perioperative MI. With 3 to 136 months follow-up (mean 41.1$\pm$40.2 months), late mortality was 1 patient due to cerebral vascular accident. Among long-term survivors, all patients are in New York Heart Association functional class I or II. Although the number of patients was small, our surgical results were favorable. Therefore we think that coronary revascularization combined with heart operation does not increase the operative risk when associated coronary artery disease is present, and it reduces the occurrence of late death.

• Communications of Mathematical Education
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• v.34 no.3
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• pp.235-256
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• 2020

The purpose of this study was to investigate the experience of pre-service mathematics teachers who attended at a university course combined with teaching practicum based on design thinking process to identify the change of their awareness of its activities. For the research, 8 pre-service mathematics teachers participated in a mathematics major course, consisting of 5 phases of design thinking formed by Stanford d.school. In the end of the course, qualitative data were collected through individual and focus group interviews and the course activities. By data analysis, the results of this study were as follows. Firstly, the participants' perspectives of design thinking activities were changed from the difficulty and ambiguity of its activity in the beginning of the process to positiveness with competence of solving authentic problem in terms of teaching practicum over time. Secondly, the participating pre-service teachers emphasized that design thinking activities helped them prepare well teaching practicum and raise understanding of students they met in the school fields. Thirdly, some research participants went through the difficulty in utilizing their products drawn from 4th phase (prototyping) of design thinking process depending on the acceptance of their guidance teachers. Fourthly, the research participants also pointed out that the design thinking was a significant activity in that they learned how to understand and communicate with their students and how to collaborate with team members and it gave an insight about the preparation for a class. Through these results, this study identified the possibility of using the design thinking process for pre-service mathematics teachers' teaching practicum. In addition, the research put forward some implications for better use of design thinking in teacher education.

• Journal of Korean Society of Forest Science
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• v.79 no.3
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• pp.245-254
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• 1990

This study was carried out to analysis the structure of forest vegetation at the southern and northern slopes of Mt. Kum in Namhae. The results obtained were summarized as follows : The upper layer of south slope at the altitude of 100m was only distributed at Pinus thunbergii and Pinus densiflora. According to increase of altitude, the importance value of Pinus thunbergii was more decreased. In the upper layer of north slope, importance value of Pinus thunbergii was very high in the altitude of 100m, and was very low in the 200m. And also, importance value of Quercus variabilis and Steuortia koreana was high from 200m to 600m. The number of individuals of Pinus thunbergii and Pinus densiflora in the south slope were more increased than those of the north slope. The distributional class of D.B.H, showed an equal tendency in south and north slope, especially-Quercus variabilis and Quercus serrata had a good growth in north slope. The stand density in the upper lacer was high in south slope but mean acreage and mean distance of individual trees showed low. The species diversity indices were relatively lower in south slope than in north slope, and the maximum of species diversity showed slightly high in south slope. The evenness showed lower in south slope than in north slope relatively. By the cluster analysis used the similarity.

• Journal of Korean Society of Forest Science
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• v.76 no.1
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• pp.17-26
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• 1987

To develop the rehabilitation measures for rockily denuded forest lands which are widely distributed in Seoul metropolitan area, erosional characteristics of denudation should, first of all, be evaluated and analysed. As a fundamental study for developing such technical measures, the rockily denuded lands were classified into 6 types according to denudation features of the mountain land, and also movements of stone debris-and-sand on rock-exposed hillslopes were measured and analysed. The 6 basic types of denudation features include a) natural rock-outcrop-exposed land, b) stone debris-and-sand scattered land, c) stone debris-and-sand deposited land, d) coarse sand producing bare land susceptible to weathering and erosion, e) dwarfed pine growing land, and f) torrential valley susceptible to the debris slides. In the stone debris-and-sand scattered hillslopes (type b), average amount of moved-down debris reached to about 3.9 ton/ha/yr due to surface washing and slidings. In the particle size distribution of the moved-down debris, it amounts to about 25% of 10-25mm, about 15% of 5-10mm, about 24% of 2-5mm, and about 36% of less than 2mm in diameter class, respectively. The detailed experimental studies should be accomplished further more about the denudation processes including weathering, erosion and debris slides on rock-exposed hillslopes.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.3
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• pp.184-193
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• 2016

Purpose: To evaluate marginal leakage of bulk fill flowable composite resin filling with different curing time by using microcomputed tomography technology. Materials and Methods: 30 previously extracted human molars were randomly divided into 6 groups based upon restorative system and different curing time. Class II cavities (vertical slot cavities) were prepared. An individual metallic matrix was used to build up the proximal wall. The SonicFill or SureFil SDR flow was inserted into the preparation by using 1 bulk increment, followed by light polymerization for different curing times. The different exposure times were 20, 40, and 60 seconds. All specimens were submitted to 5,000 thermal cycles for artificial aging. Micro-CT scanning was performed by using SkyScan 1272. One evaluator assessed microleakage of silver nitrated solution at the resin-dentin interface. The 3D image of each leakage around the restoration was reconstructed with CT-Analyser V.1.14.4. The leakage was analyzed with the Mann-Whitney test. Results: Significant differences were observed between the light curing times, but no significant differences were found between the bulk fill composite resins. Increasing in the photoactivation time resulted in greater microleakage in all the experimental groups. Those subjected to 60 seconds of light curing showed higher microleakage means than those exposed for 20 seconds and 40 seconds. Conclusion: Increasing the photoactivation time is factor that may increase marginal microlekage of the bulk fill composite resins. Further, micro-CT can nondestructively detect leakage around the resin composite restoration in three dimensions.

• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.384-388
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• 2000

For the control of Corythucha ciliata, the insecticidal activity of five commercial pesticides (Monocrotophos 25%SL, Phosphamidon 50%SL, Imidacloprid 20%DC, Thiamethoxam 15%DC and Acetamiprid 20%SL) were examined with trunk injection method in Seoul, Sanbon and Chungju. The insecticidal activity of five commercial pesticides was >88%. The insecticidal activity of Monocrotophos maintained 31 days later after trunk injection when treated leaves were supplied to this pest. This result indicates that one application of trunk injection is enough to control this pest, and this method can save the control cost compared with ground application which should be applied two or three times per year to control this pest. To make the model of treatment dosage at each D.B.H class (cm), $1.0m{\ell}/DBH$, $1.5m{\ell}/DBH$ and $2.0m{\ell}/DBH$ pesticide dosage was used. At <20cm, the insecticidal activity of $1.0m{\ell}$ dosage was >95%, and $1.5-2.5m{\ell}$ dosage was needed for the effective control at 30~50cm. More than $2.5m{\ell}$ dosage was effective at >50cm. Spray method was used in laboratory to select pesticides for ground application. Three commercial pesticides (Ethofenprox 20%EC, Ethofenprox 10%WP and Cyfluthrin 1%EC) were used, and all pesticides showed >95% insecticidal activity.

• Journal of the Korean earth science society
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• v.23 no.5
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• pp.397-405
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• 2002

This study investigated science gifted middle school students' philosophical views on scientific knowledge, and the effects of discussing and reading related to the knowledge. Ten eighth-graders in a science gifted class participated in this study. The results can be summarized as follows: 1, At the beginning, the students had one of six positions: (a) relativism (n = 2); (b) falsificationism (n = 2); (c) borderline between relativism and eclecticism (n = 1); (d) borderline between falsificationism and eclecticism (n = 3); (e) borderline among relativism, falsificationism, and eclecticism (n = 1); and (f) borderline inductivism and eclecticism (n = 1). This result indicated that most students had on almost modern philosophical view of scientific knowledge. 2, Some students, who had chosen the item of inductivism in some questions of the instrument at the beginning, maintained their selection despite discussions and readings related to scientific knowledge. The data were examples which indicated the difficulty of changing from a traditional view to a modern view of scientific knowledge.