• Journal of Korean Society of Occupational and Environmental Hygiene
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• 제19권1호
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• pp.8-15
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• 2009

This study was examined to find out asbestos exposure level the factors which affected the level at asbestos abatement sites. We visited a total of thirteen building demolition sites(3 apartments, 3 schools, 4 stores, and 3 houses) were visited to collect samples and related data from August to November, 2006. The results of this study were as follows 1. The results of an analysis of bulk samples to identify types of asbestos at the asbestos abatement sites showed that the kinds of the asbestos detected were chrysotile by 50.0%, were tremolite by 2.6%, and were the contents of chrysotile by 3 to 20%. 2. The geometric mean concentration of asbestos was 0.007 f/cc(range 0.001-0.34 f/cc) and its geometric standard deviation was 5.83. Of the samples, however, 12 exceeded the Korean Occupational Exposure Limit(0.1f/cc). 3. Of the materials, textile material had the highest concentration with geometric mean of 0.016 f/cc. When asbestos-containing materials were removed using T type tools, the geometric mean concentration of asbestos was 0.061 f/cc. The level by this method was much higher than by other removal methods. In analysis by the type of building, the geometric mean concentration of asbestos in stores was 0.042 f/cc and was higher than in other buildings. 4. The Poisson regression analysis was applied to find out the factors that affect the airborne asbestos concentration. As a result of the analysis, removal using a T type tool was the most important factor affecting the asbestos concentration(p<0.01). In conclusion, the airborne asbestos concentration(geometric mean) in asbestos abatement sites was 0.007 f/cc(0.001~0.34 f/cc), and 12(14.6%) of all samples were over the 0.1 f/cc. These results showed that asbestos abatement workers have been exposed to the high level of airborne asbestos because they have not been keeping asbestos removal rule. In accordance with increases of the number of building demolition sites, the better government regulation on asbestos abatement methods should be made and be performed well at building demolition sites.

• Journal of Life Science
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• 제22권2호
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• pp.232-238
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• 2012

Kumjungsansung-Makgeolli$^{(R)}$ is a traditional Korean rice wine that is fermented from traditional nuruk and rice. In this study, we performed the PCR-denaturing gradient gel electrophoresis (DGGE) analysis targeting the 16S and 28S rRNA genes to characterize bacterial and fungal diversity during Makgeolli fermentation. The predominant bacteria in the PCR-DGGE profile during Makgeolli fermentation were Lactobacillus spp. (Lactobacillus curvatus, L. kisonensis, L. plantarum, L. sakei, and L. gasseri), Pediococcus spp. (P. acidilactici, P. parvulus, P. agglomerans, and P. pentosaceus), Pantoea spp. (P. agglomerans and P. ananatis), and Citrobacter freundii; these were identified on the base of analysis of 16S rRNA gene sequences. The dominant bacterium during Makgeolli fermentation was L. curvatus. The predominant fungi in PCR-DGGE profile during Makgeolli fermentation were Pichia kudriavzevii, Saccharomyces cerevisiae, Asidia idahoensis, Kluyveromyces marxianus, Saccharomycopsis fibuligera, and Torulaspora delbrueckii, and these were identified on the basis of analysis of 28S rRNA gene sequences. The dominant fungal species during Makgeolli fermentation changed from P. kudriavzevii at 0-2 days incubation to S. cerevisiae at 3-6 days incubation. This study suggests that PCR-DGGE analysis could be a suitable tool for the understanding of microbial diversity and structure during Makgeolli fermentation.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제13권10호
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• pp.4523-4535
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• 2012

As a way to popularize Karatedo, a curriculum for developing excellent trainers is needed. For that, DACUM was used to specifically look into the field of duty and work that a Karatedo trainer should have, and the purpose of this study is to present fundamental data necessary for developing and organizing the curriculum of cultivating Karatedo and create a useful material that can contribute to improve Karatedo trainers' performances who are working on site. A survey using Likert scale's 7 stages was conducted on DACUM meeting data, 28 managers and 108 trainers. Based on the collected data, this study had a test in order to solve the presented subject using DACUM method and SPSS WIN Ver. 14.0. This core work through the requirements analysis process. And karate leaders the necessary knowledge, skills, and tools, and attitude analysis was carried out to perform the tasks of each. Knowledge, skills, tools and attitude for each task, toward the results of the analysis were 47 core tasks. 167 knowledge items, function 143 items, the tool 60 items, 16 attitude items reclassified a total of 18 subjects were derived. The configuration of the karate leader training program curriculum model 'Karate practical expert area', 'theory karate expert area', 'Karate gym business area experts' was composed. Basic process of how it works Step 1, Step 2 integration process, replenishment process intensified Step 3 was composed.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제13권11호
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• pp.5452-5457
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• 2012

It is saving material cost and construction cost by replacing conventional building materials, and It has advantages for aesthetic value. In the Europe, the United States, Japan and other country research about BIPV is actively being carried out and marketability is also being infinity expanding. Arch type PV systems efficiency characteristics is different depending on PV array's directly connection, parallel connection and arches angle, but is a lack of analysis on this nowadays. When the arch type PV system design up, they consider about aesthetic value and they didn't consider about generation efficiency. In this paper, we try to improve the efficiency through optimization of arch type PV system and estimation of the efficiency parameters of the arch type PV system, such as latitude, longitude, temperature, insolation, arch angle and each kind loss from system organization. For improving Arched PV system efficiency, proposed multiple control inverter system, and using simulation tool of Arched PV system "Solar pro", flat-plate type and many arch type PV system configuration the driving characteristics were compared and analyzed.

• Journal of The Korean Association of Information Education
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• 제7권1호
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• pp.27-36
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• 2003

Environmental problems can be dealt in the diverse areas such as engineering, public administration, and law. However, the education on environmental preservation is conceived as the fundamental solution for environmental problems, because the education can make the person of action. Specifically, building the attitude and habit of environmental preservation through environmental education is the effective and efficient way of environmental preservation. This research was conducted to develop an education system that is designed to build students' attitude and habit of environmental preservation through acquiring knowledge and functions of natural environment. The proposed system supports diverse learning activities such as writing, drawing, listening natural sounds and music, and problem solving. The system is technically designed on the Web to promote students' creativity and autonomy, and also are theoretically based on constructivism to build the will of environmental preservation. Moreover, the proposed Web-based system includes diverse functions such as classes, material resources, environmental quiz pool, environmental work gallery, which motivate students' learning activities. Therefore the proposed Web-based system is expected as an effective tool to achieve the goals of environmental education such as acquiring environmental knowledge and functions, building attitude of environmental preservation, and participating in the environmental preservation activities.

• The Journal of the Acoustical Society of Korea
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• 제33권5호
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• pp.300-308
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• 2014

Photoacoustic imaging is a useful tool for the diagnosis of atherosclerosis because it is capable of providing anatomical and pathological information at the same time. A photoacoustic signal detector is a pivotal element to achieve high spatial resolution, so that it should have broadband spectrum with a high center frequency. Since a photoacoustic imaging probe is directly inserted into blood vessel to diagnose atherosclerosis, the total size of the photoacoustic signal detector should be less than 1 mm. The main purpose of this paper is to demonstrate that PVDF can be used as an active material for the photoacoustic signal detector with a high frequency and broadband characteristic. The photoacoustic signal detector developed in this study was a single element ultrasound transducer with an aperture of $0.5{\times}0.5mm$ and the total size of 1 mm. In the design stage, the natural focal depth was adjusted for an effective focal area to cover the region of interest, i.e., 1~5 mm in depth. This was because geometrical focusing could not be used due to the small aperture. Through a pulse-echo test, it was ascertained that the developed photoacoustic signal detector has the -6 dB bandwidth ranging between 40.1 and 112.8 MHz and the center frequency of 76.83 MHz.

• Journal of Elementary Mathematics Education in Korea
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• 제20권4호
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• pp.695-715
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• 2016

This study is on the teaching method for the students who belong to the same school (one, the gifted class, passed gifted education of Science High school ), 1-1, face-to-face learning (two, good students in regular classroom) with a teacher, paired learning teams (4 people, gifted classes), and group lessons (20 people, gifted classes) and using the justification analysis framework tool(PIRSO) of Kim(2010) analyzes the justification element of the students in the group classes regular polygons paper was to explore ways to improve the justification of the folding maps activities. As a result, the width of the largest polygon difficulty level appropriate to the class for gifted elementary school classes but the individual learning style of the 1-1 face-to-face with a teacher or discussion with colleagues and cooperative approach is justified, rather than the material of the study of origami activities it turned out to be more effective in improving the level of justification. Unlike the individual learning activities, the exploration for class is the need to strain in parallel to the student is selected as needed, rather than serial manner was confirmed that it is necessary to clearly present problems even from the beginning. Development of teaching through the implications obtained from this method of reconstruction activities and proposed improvement measures for questioning.

• Journal of the Korean Institute of Gas
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• 제21권4호
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• pp.84-91
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• 2017

Recent years have witnessed the increased usage of flammable metals, such as aluminum or magnesium, in wide range of high-tech industries. These metals are indispensable for the improvement of physical properties of materials as well as the design capability of the final product. During the process, unwanted metal dusts could be released to the environment. This can lead to an occupational health and safety issues. Due to their flammable nature, more serious problem of an explosion can happen in extreme cases. The explosion is the combustion of tiny solid particles and vapor mixture, caused by pyrolysis. This complex composition makes engineering analysis more difficult, compared to simple gas explosions or vapor cloud combustions. The study was conducted to assess this light metal dust explosion in an effort to provide the bases for a risk assessment. Dust explosion characteristics of each material was carefully evaluated and an appropriate analysis tool was developed. A comprehensive database was also constructed and utilized for the calibration of the developed response model and the verification for its accuracy. Subsequently, guidelines were provided to prevent dust explosions that could occur in top-notch industrial processes.

• Applied Chemistry for Engineering
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• 제8권5호
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• pp.742-748
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• 1997

Diamond films which have high hardness and thermal conductivity can be used to improve the performance of WC-Co as a cutting tool material. However, it is difficult to get such coatings of good uniformity and adhesiveness due to the surface characteristics of WC-Co. To get better coatings, some techniques, such as the surface treatment of substrate or the formation of interlayer between substrate and diamond film, have been tried. In the present work, the nickel interlayer is formed onto WC-Co by electroless Ni-P plating, which is introduced as a new method, and then diamond film is deposited on the interlayer. Formation and uniformity of three layers, i.e., substrate, electroless plate, and diamond film, and the adhesiveness of interlayers were studied. To investigate the effects of pretreatment on electroless plating, two different methods such as acid treatment and diamond powder treatment were used. The effects of heat treatment of the electroless plated surface on adhesiveness between the substrate and the interlayer were examined. It was found that as the temperature increases, the Ni crystals grow and then result in improved adhesiveness. Diamond film coatings of pure diamond phase were obtained at $800^{\circ}C$. It is concluded that the heat treated electroless Ni-P plating can be effectively used as a interlayer between WC-Co substrate and diamond film.

• The korean journal of orthodontics
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• 제33권6호
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• pp.465-474
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• 2003

The great variety of commercial brands of orthodontic wires available on the market, stimulated by the so called superior wires (nickel titanium with shape memory effect and superelastic nickel titanium), makes the professional choice for a suitable and less expensive material difficult. The in vitro study of the mechanical properties of the orthodontic wires acts as an auxiliary tool for the professional. In this paper, a comparative study of mechanical properties was made, using stress strain tests for 4 types of orthodontic wires (conventional stainless steel, multistranded steel, superelastic nickel titanium and thermoactivated nickel titanium) separated into 5 groups. A series of 6 tests were tested for each group of wires. Initially, each group was tested 3 times until the wires broke. Furthermore, 3 more tests for each group were performed, stretching the wires under standardized activation loads, for a reliable comparison of their mechanical properties, during loading and unloading. 1 tests were applied to check differences among the groups. In vitro, the results suggest that regarding the mechanical properties supposedly desirable for physiological teeth movement, such as resilience, elasticity modulus, strength liberated during unloading, and the way that strength is liberated, thermoactivated nickel titanium wires, acting under mouth temperature, seems to be a good choice, fellowed by superelastic nickel titanium, multistranded stainless steel, and conventional stainless sleet. Superelasticity was demonstrated for superelastic nickel titanium wires. When at $37^{\circ}C$, thermoactivated nickel titanium wires showed shape memory effect, showing that temperature is important for enhancing the mechanical properties.