• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.40 no.4
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• pp.173-180
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• 2014

Objectives: The purpose of this study was to investigate the neurogenic differentiation of human dental pulp stem cells (DPSCs), periodontal ligament stem cells (PDLSCs), and stem cells from apical papilla (SCAP). Materials and Methods: After induction of neurogenic differentiation using commercial differentiation medium, expression levels of neural markers, microtubule-associated protein 2 (MAP2), class III ${\beta}$-tubulin, and glial fibrillary acidic protein (GFAP) were identified using reverse transcriptase polymerase chain reaction (PCR), real-time PCR, and immunocytochemistry. Results: The induced cells showed neuron-like morphologies, similar to axons, dendrites, and perikaryons, which are composed of neurons in DPSCs, PDLSCs, and SCAP. The mRNA levels of neuronal markers tended to increase in differentiated cells. The expression of MAP2 and ${\beta}$-tubulin III also increased at the protein level in differentiation groups, even though GFAP was not detected via immunocytochemistry. Conclusion: Human dental stem cells including DPSCs, PDLSCs, and SCAP may have neurogenic differentiation capability in vitro. The presented data support the use of human dental stem cells as a possible alternative source of stem cells for therapeutic utility in the treatment of neurological diseases.

• Journal of the Korean Society for Library and Information Science
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• v.27
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• pp.3-73
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• 1994

It is widely known that the public library in Korea has not been developed as a social agency which makes communication process possible. The public library in Korea just plays a role of the public study room for students using their own books. There is almost no public libraries in the sense of an open collection of comprehensive materials designed for use by anyone who seeks information. This study starts from this situation. It aims at identifying the present stage of the development of public libraries in Korea through investigating librarians' consciousness in their everyday lives. For this, a case study method is used for investingating, collecting and organizing the 'discourse' of librarians in Pusan and Kyongsangnamdo area. Major suggestions include : First of all, it is most important for public library reformation to eradicate the 'conservatism' in the consciousness of librarians in their everyday lives. So, it is essential to collect their life stories in various library conditions, and make them public discourse of librarians. Secondly, the professional organization should play a role to unify the librarians. For this role, it should maintain a R&D department and strengthen PR programs. Thirdly, Researchers who study Library and Information Science in Korea should be always concerned with the real-life context in the field. The most important type of research in our third world situation is the one that is based on the present stage of the development of our own libraries and the real library situation in the field.

• Journal of the Korean School Mathematics Society
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• v.22 no.3
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• pp.241-256
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• 2019

In this paper, we analyzed the types of tasks presented in the 'Probability and Statistics' textbooks and how the cognitive competences required to perform the tasks provide students with opportunity-to-learn. To this end, the analysis of the 9 books of the 'Probability and Statistics' test textbooks according to the 2015 revised mathematics curriculum showed that the context-based tasks(CF type, RE type) ranged from 67.5% to 78.0% of the total number of tasks in each textbook, but the ratio of relevant and essential tasks related to real life is from 0.4% to 2.0%, it was found that most of the context-based tasks presented in the textbooks were disguised as real life materials. The cognitive competences of context-based tasks ranged from 29.6% to 50.0% in reproduction category, from 33.8% to 54.3% in connection category, and from 8.8% to 20.0% in reflection category. As a result, there was not enough opportunity-to-learn for students to experience reflective cognitive processes.

• School Mathematics
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• v.16 no.1
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• pp.83-110
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• 2014

This study analyzed the mathematics textbooks of middle grades in the first Korean curriculum, based on the modern trends of mathematics education curriculum, comparing with present Korean curriculum's other textbooks and the American textbook, MiC. The mathematics textbooks in the first Korean curriculum are based on various situations in our real life and introduce mathematical concepts throughout a set of mathematics problems. The textbooks present mathematical concepts with connected knowledge and include mathematical activities which make students use mathematical table, graph and formula at the same time. And students are actively required to discuss together during the mathematics problem solving process. As the results of this modern review on Korean 1st curriculum and middle grades mathematics textbooks, it would provide preliminary data and meaningful implications for the next curriculum and concomitant instructional materials.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.136-144
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• 2021

The purpose of this study was to develop and verify a precision transmission error measurement system for a gear pair. The transmission error measurement system of the gear pair was developed as a measurement unit, signal processing unit, and signal analysis unit. The angular displacement for calculating the transmission error of the gear pair was measured using an encoder. The signal amplification, interpolation, and transmission error calculation of the measured angular displacement were conducted using a field-programmable gate array (FPGA) and a real-time processor. A high-pass filter (HPF) was applied to the calculated transmission error from the real-time processor. The transmission error measurement test was conducted using a gearbox, including the master gear pair. The same test was repeated three times in the clockwise and counterclockwise directions, respectively, according to the load conditions (0 - 200 N·m). The results of the gear transmission error tests showed similar tendencies, thereby confirming the stability of the system. The measured transmission error was verified by comparing it with the transmission error analyzed using commercial software. The verification showed a slight difference in the transmission error between the methods. In a future study, the measurement and analysis method of the developed precision transmission error measurement system in this study may possibly be used for gear design.

• Journal of the Korean Society of School Health
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• v.6 no.2
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• pp.24-55
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• 1993

School health aims to guide and manage growing students from elementary schools to high schools in order to grow healthily through the formation of healthy life habits, the self-control health management guide and the making of pleasant school health environments. Even though this school health plays an important role in guiding the students who are in the period of growing to have a perfect personality as a democratic people of our country in the school education, there are many lacks, such as they still don't know the word itself, "school health" or recognize its importance. Also it's a real condition to practice items concerned with the health under the condition of unestablished structure. 1. The results of analyzing school health real conditions. Based on treatises concerned with school health and various statistical materials which are announced by concerned people. We divided and analyzed school health into the items concerned with health education, the items with health management, and the items with school health environments, and investigated the level of the present school health and its necessity. As the items concerned with health education, we investigated the necessary range of school health education, the effect of health education on children's daily life, family's health and the interesting contents of school health. And as the items with health management, I investigated children's obesity, dental caries, eyesight, clinics, a health examination, drug abuse, spirit health, providing meals for school children, and school health manpower. And as the items conerned with school health environments, we investigated the recognition of the problem of natural environments, the management of purification district around the school, the problem of environments within the school and classroom lighting. As the results of analyzing these, I realized that the present level of school health is still in unsatisfactory situation and school health is needed necessary. 2. The establishment of school health. In order to set the school health, above all, the management system of School health should be set. I classified and systemized the contents of each item which had been promoted till now according to the function. They are classified as followings Based on classifying school health into (1) health education, (2) health management and (3) health environments, I divided school health education into the health education of health subjects, the health education of concerned subjects and the education of health life. And I divided health management into the health managements for a prevention and a cure. And I divided health environments into the environment around the school and within the school. Each system set like these is not fixed invariably and I should keep the relationship of mutual supplement between health education and health management, between health management and health environments, and between health environments management and health education. When we run these systemetic school health, students' health could be maintained and improved to more proper directions.

• 대한공업교육학회지
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• v.37 no.2
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• pp.57-75
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• 2012

The purpose of this study was to survey and analyze the recognition and needs of elementary school teachers about STEAM education. Mail and E-mail surveys were conducted for 533 elementary school teachers for the purpose of the study. The following were found results of the study were as follow: First, although elementary school teachers understood positively the necessity of STEAM education, showed average levels of recognition on STEAM education. Second, the rate of the elementary school teachers who had experience in applying STEAM education was low. Third, elementary school teachers required to education closely related to real life, and interesting education according to the direction for STEAM education. Fourth, elementary school teachers asked for the integration centering activities related real life, followed by the integration focusing on thema related to real life, the integrating centering student's needs and interests, and the integration focusing on issues according to the appropriate integration methods for STEAM education. Fifth, elementary school teachers required creative design/problem solving ability, academic performance ability, and interpersonal relationship skills with regard to the ability to develop through STEAM education. Lastly, elementary school teachers demanded the development and distribution of STEAM education, teacher's recognition and attitudes towards STEAM education, teacher's training for STEAM education, the distribution of reference materials and etc in order to stimulate STEAM education.

• KIEAE Journal
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• v.10 no.6
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• pp.145-151
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• 2010

Bearing wall system was used extensively in most multi-residential apartment buildings in Korea. However, bearing wall apartments have the lack of architectural plan flexibility, remodelling-incompatible, causing serious economic losses in terms of construction waste. Recently, many researchers have studied the use of Rahmen structure as a potential alternative. The beam-column connection in the paper for long-life apartment housing forms connection of a Rahmen structure utilizing the advantages of steel and reinforced concrete. In addition, reduction of cast-in place concrete and construction schedule is expected by using precast concrete. Reduction effect of quantity decreased construction costs and $CO_2$ emission of key construction materials. However, verifying the feasibility of new construction method entails numerous challenges. Accordingly, the purpose of this study is to analyze the construction feasibility of sleeve, coupler, and pressure welding connections for long-life apartment building structure. A 3D modeling software was used to perform the analysis, and a real scale model was created to verify the results of construction feasibility. By verifying the construction feasibility of beam-column connections, this study will contribute to the efficient application of these methods on construction sites.

• Journal of the Ergonomics Society of Korea
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• v.30 no.1
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• pp.151-160
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• 2011

There have been many efforts to prevent accidents in Korea for the last 25 years. Many measures in the area of hardware sciences including electrical, mechanical, chemical engineering, etc. were applied to eliminate or at least reduce causes of accidents. However, the accidents rate has not been reduced much despite of these measures. This research aimed to find real causes of these accidents and to suggest a comprehensive model that can mainly be applied to industrial fields to find potential or existence of human errors during the pre-installation stage or after an accident. We tried to explain sequences of an operator's information process that might cause human errors on one hand, and life cycle stages of facilities involved when human errors occur on the other hand. With this comprehensive model presented in this research, one can follow up the sequence of human errors caused by operators. Further, errors made at the design stage which could be a main cause of accidents can be tracked. It is recommended that this comprehensive model should be used to prevent human errors in industrial fields since safety personnel can easily find out errors or error potentials through the life cycle stages of manmachine facilities.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.1025-1028
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• 2005

Generally, fiber-reinforced composites have the highest possibilities of impact damages with external object collisions. Also, resulting in fatigue fracture considering the continued impact load. For the reasons mentioned above, the accurate understanding of interactions between the impact of composites and the fatigue load will be essential to understand the safety level of material structures. Furthermore, the composite materials and structures, due to the geometrical effect, vary the life in connection with the impact-fatigue. Therefore, I have reached the point that a focus of this study will be to evaluate fatigue fracture characteristics by the impacts-fatigue load of fiber-reinforced composites. Thus, in this paper, I have tried to work on impacts-fatigue load causing aspects and impact characteristics through impact-fatigue test on HTV-5Hl Black 9250 material made- structure, along with to evaluate the expected lift of real structures, the FEM analysis was carried out.