• Journal of the Korea Convergence Society
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• v.6 no.6
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• pp.293-299
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• 2015

MOOC (Massive Open Online Course) is an online course aimed at limited participation and open access via the web. There is even the prospect that MOOC may break down the existing university system and open a new horizon of education. However, MOOC is going differently from the first prospect that it would threat the existing higher education institutions. So this study wishes to provide a starting point of discussion that we can produce and utilize MOOC to fit our situation of higher education by revealing the inherent problems of MOOC. MOOC is a basically online education, so that it cannot help inheriting the essential weakness of the existing one: the interaction, supervision and evaluation. The newly added concept 'massive' raises the problem of class size which is the most sensitive part in the field of education. The concept 'open' reverses a customized education because MOOC is a kind of video clips of a lecture for unspecific massive learners. As a conclusion, we predicts that MOOC will be positioned as a higher education service for very prominent learners in self-led learning ability and people who cannot access even traditional online higher education institutions. Also MOOC is highly likely to be used as a means of Flipped Learning in universities. Therefore, considering these points in the future, we need to develop MOOC to suit these targets.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.247-254
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• 2014

Strain properties of concrete member which acts as an important factor in the stability of the concrete structure in the event of fire, significantly affected the characteristics of the coarse aggregate, which accounts for most of the volume. For this reason, there are many studies on concrete using artificial lightweight aggregate which has smaller thermal expansion deformation than granite coarse aggregate. But the research is mostly limited on concrete using clay-based lightweight aggregate. Therefore, in this study, the high temperature compressive strength and elastic modulus, thermal strain and total strain, high temperature creep strain of concrete was evaluated. As a result, remaining rate of high-temperature strength of concrete using lightweight aggregate is higher than concrete with general aggregate and it is determined to be advantageous in terms of structural safety and ensuring high-temperature strength from the result of the total strain by loading and strain of thermal expansion. In addition, in the case of high-temperature creep, concrete shrinkage is increased by rising loading and temperature regardless of the type of aggregate, and concrete using lightweight aggregate shows bigger shrinkage than concrete with a granite-based aggregate. From this result, it is determined to require additional consideration on a high temperature creep strain in case of maintaining high temperature like as duration of a fire although concrete using light weight aggregate is an advantage in reducing the thermal expansion strain of the fire.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.4
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• pp.384-392
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• 2013

Objective: This study inspected incident cases, legal control levels, and GHS(Globally Harmonized System of Classification and Labeling of Chemicals) classification results of strong acids such as hydrogen fluoride, hydrogen chloride, nitric acid, and sulfuric acid, which have been responsible for many recent chemical accidents. As a result, it is deemed necessary for legal control levels of these strong acids to be revised and GHS classification be managed nation-wide. Methods: This study inspected incident cases and legal control levels for strong acids such as hydrogen fluoride, hydrogen chloride, nitric acid, and sulfuric acid. The study analyzed and compared chemical information status and GHS classification results. Results: There were 76 domestic incidents involving strongly acidic hazardous materials over the five years between 2007 and 2011. They include 37 leakage incidents(46.7%) within a workplace, 30 leakage incidents(39.5%) during transportation, and nine leakage incidents(13.8%) following an explosion. The strongly acidic materials in question are defined and controlled as toxic chemicals according to the classes of Substances Requiring Preparation for Accidents, Managed Hazardous Substance, Hazardous Chemical(corrosive) as set forth under the Enforcement Decree of the Toxic Chemicals Control Act and Rules on Occupational Safety and Health Standards of Occupational Safety and Health Act. Among them, nitric acid is solely controlled as a class 6 hazardous material, oxidizing liquid, under the Hazardous Chemicals Control Act. The classification results of the EU ECHA(European Chemicals Agency) CLP(Commission Regulation(EC) No. 790/2009 of 10 August 2009, for the purposes of its adaptation to technical and scientific progress, Regulation(EC) No 1272/2008 of the European Parliament and of the Council on classification, labeling and packaging of substances and mixtures) and NIER (National Institute of Environmental Research) are almost identical for the three chemicals, with the exception of sulfuric acid. Much of the classification information of NITE (National Institute of Technology and Evaluation) and KOSHA(Korea Occupational Safety and Health Agency, KOSHA) is the same. NIER provides 12(41.4%) out of 29 classifications, as does KOSHA.

• Journal of Korean Elementary Science Education
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• v.29 no.4
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• pp.552-566
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• 2010

This paper is an in-depth case study to analyze integrated elementary science lesson planning and practical teaching by two teachers at an urban elementary schools. One is an experienced teacher and the other is a beginning teacher. For this study, researchers asked teachers to design 5 stages of lesson planning after sharing basic theories about the integrated science education. The first of the 5 lesson planning stages is curriculum analysis and choice of integrated science topic. The second stage is constructing the frame of integrated science lesson contents, and the third is drawing a diagram of the integrated science lesson development. The fourth stage is making a table of lesson plans, and the last stage is writing integrated science lesson plans. Then, the teachers implemented the lessons they created. They taught students one unit of science which is composed of 8 lessons. Difficulties that teachers meet during designing plans and integrated science class were analyzed. 5 staged lesson planning, video transcriptions, teacher interview about lesson planning and teaching, researchers' checklists, reports of inspection classes, teachers' self evaluation, and students interviews were used for this study. One of the significant results of this study is that both experienced and beginning teachers had many difficulties in deciding on time to teach and contents of science and other subjects, as well as selection and organization of whole topics of integrated science teaching. The beginning teacher especially had greater issues with developing definite teaching-learning strategy to conduct thoughts and views for integrated science at the whole unit and each lesson. However, the experienced teacher was using various teaching-learning strategies by utilizing integrated science teaching professionalism to develop students' integrated thinking ability during the instruction of other subjects. The outcomes of this study are that both teachers could deeply understand the need and value of integrated science education at the elementary school through planning and teaching 8 lessons, and that they could have self-confidence with development of teaching professionalism for integrated science teaching. It may be possible that this study could help the development of pre- and in-service program for improvement of integrated science teaching professionalism for elementary school teacher.

• Journal of The Korean Association For Science Education
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• v.40 no.4
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• pp.375-383
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• 2020

In this study, we investigated the effects of the multiple representation-based learning strategies using augmented reality in terms of students' conceptual understanding, achievement, and enjoyment of science lessons. 136 8^th-grade students in a coed middle school were randomly assigned to the treatment and the control group. The students learned the concept of the particulate nature of matter related to the properties of substances for four class periods. The multiple representation-based learning strategies designed to facilitate the connecting and integrating representations provided from augmented reality were developed and administered to the students of the treatment group. Results of two-way ANCOVA revealed that the scores of a conceptions test and enjoyment of science lessons test of the treatment group were significantly higher than those of the control group, regardless of their prior science achievement. In a conceptions test, there was a significant difference in the concept of preservation of particles. However, the difference was not statistically significant in the concept of distribution and motion of particles. In terms of an achievement test, there was a significant interaction effect by their prior science achievement. The scores of low-level students were significantly improved, but the effects were not significant to high-level students. On the bases of the results, educational implications for effective teaching and learning using augmented reality are discussed.

• Journal of Periodontal and Implant Science
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• v.25 no.3
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• pp.603-613
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• 1995

The purpose of this investigation was to evaluate on the biodegradability, biocompatibility and tissue regenerative capacity of synthetic bioabsorbable membranes in beagle dogs. For animal study, 9 adult beagle dogs were used to examination, on the surgical implantation of membranes and histological analysis. In each animal, the 3rd and 4th premolars of the both sides of the mandible were selected as test teeth. Two types of bioresorbable membranes including "Guidor membrane", "S-membranes" were used to examining for biological activity, and also Gore-tex membranes was used for positive control. Surgically created defects were made in 2 premolars of both sides of the mandible at $3{\times}4mm^2$ in size and tested membranes were implanted in the defected area. A plaque control regimen was instituted with daily tooth brushing with a 0.1% chlorhexidine digluconate during experimental periods. All the experimental animals were sacrificed after 2, 4, and 8 weeks from surgery and undecalcified slides were prepared using the "sawing and grinding" technique described by Donath and Breuner". In biodegradability, all the membranes were started their biodegradation from two weeks after implantation and gradually demolished of their frame morphology from eight weeks. However, demolition of membranes in 8 weeks after implantation was highest in Guidor membranes and followed by S-membranes. Biocompatibilityof two kinds of biodegradable membranes including Guidor and S-mambrane were shown to be well tolerated to the surrounding tissue, and were minimal accumulation of inflammatory cell infiltration around the implanted membranes to compare with Gore-tex membrane. Regeneration of defected alveolar bone was initiated from two weeks of membrane implantation and new bone formation was gradually increased from that time. However, pattern of new bone formation on the defected areas of two kinds of biodegrable membranes was almost similar and quite competitive comparing with Gore-tex membrane. These results implicate that bioresorbable membranes should be highly useful tool for guided tissue regeneration of periodontal defects.

• Investigative Magnetic Resonance Imaging
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• v.19 no.3
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• pp.178-185
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• 2015

Purpose: To compare the frequency of posterior globe flattening between two-dimensional T2-weighted imaging (2D T2WI) and three-dimensional (3D T2WI). Materials and Methods: Sixty-nine patients (31 female; mean age, 44.4 years) who had undergone both 5-mm axial T2WI and sagittal 3D 1-mm isovoxel T2WI of the whole brain for evaluation of various diseases (headache [n = 30], large hemorrhage [n = 19], large tumor or leptomeningeal tumor spread [n = 15], large infarct [n = 3], and bacterial meningitis [n = 2]) were used in this study. Two radiologists independently reviewed both sets of images at separate sessions. Axial T2WI and multi-planar imaging of 3D T2WI were visually assessed for the presence of globe flattening. The optic nerve sheath diameter (ONSD) was measured at a location 4 mm posterior to each globe on oblique coronal imaging reformatted from 3D T2WI. Results: There were significantly more globes showing posterior flattening on 3D T2WI (105/138 [76.1%]) than on 2D T2WI (27/138 [19.6%], P = 0.001). Inter-observer agreement was excellent for both 2D T2WI and 3D T2WI (Cohen's kappa = 0.928 and 0.962, respectively). Intra-class correlation coefficient for the ONSD was almost perfect (Cohen's kappa = 0.839). The globes with posterior flattening had significantly larger ONSD than those without on both 2D and 3D T2WI (P < 0.001; $6.14mm{\pm}0.44$ vs. $5.74mm{\pm}0.44$ on 2D T2WI; $5.90mm{\pm}0.47$ vs. $5.56mm{\pm}0.34$ on 3D T2WI). Optic nerve protrusion was significantly more frequent on reformatted 1-mm 3D T2WI than on 5-mm 2D T2WI (8 out of 138 globes on 3D T2WI versus one on 2D T2WI; P = 0.018). Conclusion: Posterior globe flattening is more frequently observed on 3D T2WI than on 2D T2WI in patients suspected of having increased intracranial pressure. The globes with posterior flattening have significantly larger ONSD than those without.

• School Mathematics
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• v.13 no.4
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• pp.651-674
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• 2011

Functional thinking is a central topic in school mathematics and the purpose of teaching functional thinking is to develop student's functional thinking ability. Functional thinking which has to be taught in elementary school must be the thinking in terms of phenomenon which has attributes of 'connection'- assignment and dependence. The qualitative methods for evaluation of development of functional thinking can be based on students' activities which are related to functional thinking. With this purpose, teachers have to provide students with paradigm of the functional situation connected to the other subjects which have attributes of 'connection' and guide them by proper questions. Therefore, the aim of this study is to find teaching method for functional thinking by situation posing connected with other subject. We suggest the following ways for functional situation posing though the process of three steps : preparation, adaption and reflection of functional situation posing. At the first stage of preparation for functional situation, teacher should investigate student's environment, mathematical knowledge and level of functional thinking. With this purpose, teachers analyze various curriculum which can be used for teaching functional thinking, extract functional situation among them and investigate the utilization of functional situation as follows : ${\cdot}$ Using meta-plan, ${\cdot}$ Using mathematical journal, ${\cdot}$ Using problem posing ${\cdot}$ Designing teacher's questions which can activate students' functional thinking. For this, teachers should be experts on functional thinking. At the second stage of adaption, teacher may suggest the following steps : free exploration ${\longrightarrow}$ guided exploration ${\longrightarrow}$ expression of formalization ${\longrightarrow}$ application and feedback. Because we demand new teaching model which can apply the contents of other subjects to the mathematic class. At the third stage of reflection, teacher should prepare analysis framework of functional situation during and after students' products as follows : meta-plan, mathematical journal, problem solving. Also teacher should prepare the analysis framework analyzing student's respondence.

• Journal of the Korean Society of School Health
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• v.12 no.2
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• pp.217-230
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• 1999

The purpose of this study is to find out problems in obesity management through survey and analysis of the actual conditions from the view of a elementary schools school-nurses and to establish fundamental data for efficient obesity management. The subjects for this study were 313 numbers of elementary school-nurses in Kyung-Sang-Pook-Do. The data were collected through mail questionaries from November 1 to November 30, 1997. The major findings in this survey were as follows: 49.8% of the school-nurses who responded in the survey were in their 30s. The average career was 7.3years. The average service duration in their present school was 2.3 years, 55.6% of them were serving at schools which have less than ten classes total 77.2% of them were serving rural areas, 79.6% of them were serving at schools with fewer than 100 obese students. The total obesity prevalence rate was 11.4%, 13.3% were girls, 9.3% were boys. The measurement of height and weight is performed once a year for all surveyed students (91.7%), but obese students were measured as much five times (51.1%). The rate of obesity management planning was 74.1%, however the rates of evaluation and role assignment were 41. 2%, and 24.3%. 79.6% of the surveyed schools have health education classes for obesity, the rate compared (8.0 periods per year) to the whole of health education (79.1 periods per year) is 10.1%. 99.9% of the schools had counseling rooms for obesity (combined with nursing rooms) but they were used. The roote of individual counseling was 84.3%. The frequency counseling was six times a year for about 15 minutes. Obesity counseling records were kept 93.6% of the time and individual information cards were kept 98.7% of the time. The frequency of parents counseling was 42.8% and the survey shows that the main problem here was insufficient counseling facilities. The frequency of dietary guidance and exercise therapy was 84.3% and the dietary instructor was usually the school nurse at 51.7%. The frequency of obesity student exercise was 1-2 times a week and more-than-10-minutes at a time. They skip rope during the morning self-study class. The number on problem of exercise guidance at 56.2% was students' non-cooperativeness. School-nurses, 87.9%, answered that obesity management at school is necessary and 86.9% mentioned the shortage of obesity related information in present physical exercise books. From the plural responses of executing the obesity management, there are many similar problems: lack of knowledge and non-cooperation in parents at 41.9%, is predominant followed by of knowledge and non-cooperation in the children. The third problem is the lack of funds and facilities.

• Journal of Chest Surgery
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• v.27 no.4
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• pp.272-280
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• 1994

Total 400 St.Jude Medical Bileaflet Valves were implanted in 336 pts from January 1983 to June 1993; 64 were aortic, 205 were mitral, 64 were double valve and 3 were tricuspid position. The follow up period extended from 6 months to 10 years[mean 24.3 months]. Male to female ratio was 1:1.7. There were total 27 deaths[cardiac related 20, cardiac non-related 7]. Overall mortality was 2.9%/pt-yr. There were 10 early deaths[3.0%] and 10 late cardiac related deaths [3.0%]. Prosthetic valve related complications occurred in 19 patients[5.7%] and among them, seven died; four died of thromboembolic events, two died of anticoagulants therapy related hemorrhagic complications and one died of bacterial endocarditis. NYHA class improved significantly especially in aortic valve replacement and double valve replacement. In AVR cases, the mean NYHA was 2.8 preoperatively and 1.3 postoperatively. And in DVR cases, 3.3 preoperatively and 2.2 postoperatively. The decision to employ a particular prosthesis was made according to the anticipated or known complications of the valve. The St.Jude Medical Valve retains all the hazards of other mechanical valves, most notably, thromboembolism. But the hemodynamic performance of St.Jude Medical Valve compared most favorably with other substitute valves in many reports. 0ur experience didn`t show any differences compared other authors in terms of valve related complication. So we concluded St. Jude Medical Valve can be primarily considered in the selection of artificial valve except in the patients when the usage of anticoagulant therapy is contraindicated.