• Journal of The Korean Association For Science Education
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• v.40 no.2
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• pp.217-226
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• 2020

The purpose of this research is to draw suggestions on the settling of the 2015 revised curriculum and the direction of science curriculum improvement by identifying the current status of science general elective courses for high school sophomores, and examining teachers' perception. To this end, with 12 city and provincial education offices' cooperation, we analyzed the status of science elective subjects that freshmen took in 2018 by school year, school type and region. In addition, in-depth interviews were conducted with nine science teachers of the focus group to discuss ways to improve curriculum operation and implementation of science general elective courses, and ways to raise the selection rate. The number of science general elective courses for high school students in 12 municipal and provincial education offices was confirmed to be 163,710 for Physics I, 216,754 for Chemistry I, 290,736 for Bioscience I, and 200,861 for Earth Science I. By school type, autonomous high schools have the highest completion rate, while specialized schools and vocational schools have very low rates. Units completed per semester for general elective courses were mostly three units (61.5%) and two units (28.7%). High school science teachers suggested reconstruction of three-unit elective courses that can be completed in one semester, content development focused on competences rather than knowledge, and the need for a teacher community to improve teachers' teaching competences. Based on the results of the research, ways to operate high school science elective curriculum in preparation for the high school credit system were suggested.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2003.10a
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• pp.34-63
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• 2003

Occupational and environmental exposure to manganese continue to represent a realistic public health problem in both developed and developing countries. Increased utility of MMT as a replacement for lead in gasoline creates a new source of environmental exposure to manganese. It is, therefore, imperative that further attention be directed at molecular neurotoxicology of manganese. A Need for a more complete understanding of manganese functions both in health and disease, and for a better defined role of manganese in iron metabolism is well substantiated. The in-depth studies in this area should provide novel information on the potential public health risk associated with manganese exposure. It will also explore novel mechanism(s) of manganese-induced neurotoxicity from the angle of Mn-Fe interaction at both systemic and cellular levels. More importantly, the result of these studies will offer clues to the etiology of IPD and its associated abnormal iron and energy metabolism. To achieve these goals, however, a number of outstanding questions remain to be resolved. First, one must understand what species of manganese in the biological matrices plays critical role in the induction of neurotoxicity, Mn(II) or Mn(III)? In our own studies with aconitase, Cpx-I, and Cpx-II, manganese was added to the buffers as the divalent salt, i.e., $MnCl_2$. While it is quite reasonable to suggest that the effect on aconitase and/or Cpx-I activites was associated with the divalent species of manganese, the experimental design does not preclude the possibility that a manganese species of higher oxidation state, such as Mn(III), is required for the induction of these effects. The ionic radius of Mn(III) is 65 ppm, which is similar to the ionic size to Fe(III) (65 ppm at the high spin state) in aconitase (Nieboer and Fletcher, 1996; Sneed et al., 1953). Thus it is plausible that the higher oxidation state of manganese optimally fits into the geometric space of aconitase, serving as the active species in this enzymatic reaction. In the current literature, most of the studies on manganese toxicity have used Mn(II) as $MnCl_2$ rather than Mn(III). The obvious advantage of Mn(II) is its good water solubility, which allows effortless preparation in either in vivo or in vitro investigation, whereas almost all of the Mn(III) salt products on the comparison between two valent manganese species nearly infeasible. Thus a more intimate collaboration with physiochemists to develop a better way to study Mn(III) species in biological matrices is pressingly needed. Second, In spite of the special affinity of manganese for mitochondria and its similar chemical properties to iron, there is a sound reason to postulate that manganese may act as an iron surrogate in certain iron-requiring enzymes. It is, therefore, imperative to design the physiochemical studies to determine whether manganese can indeed exchange with iron in proteins, and to understand how manganese interacts with tertiary structure of proteins. The studies on binding properties (such as affinity constant, dissociation parameter, etc.) of manganese and iron to key enzymes associated with iron and energy regulation would add additional information to our knowledge of Mn-Fe neurotoxicity. Third, manganese exposure, either in vivo or in vitro, promotes cellular overload of iron. It is still unclear, however, how exactly manganese interacts with cellular iron regulatory processes and what is the mechanism underlying this cellular iron overload. As discussed above, the binding of IRP-I to TfR mRNA leads to the expression of TfR, thereby increasing cellular iron uptake. The sequence encoding TfR mRNA, in particular IRE fragments, has been well-documented in literature. It is therefore possible to use molecular technique to elaborate whether manganese cytotoxicity influences the mRNA expression of iron regulatory proteins and how manganese exposure alters the binding activity of IPRs to TfR mRNA. Finally, the current manganese investigation has largely focused on the issues ranging from disposition/toxicity study to the characterization of clinical symptoms. Much less has been done regarding the risk assessment of environmenta/occupational exposure. One of the unsolved, pressing puzzles is the lack of reliable biomarker(s) for manganese-induced neurologic lesions in long-term, low-level exposure situation. Lack of such a diagnostic means renders it impossible to assess the human health risk and long-term social impact associated with potentially elevated manganese in environment. The biochemical interaction between manganese and iron, particularly the ensuing subtle changes of certain relevant proteins, provides the opportunity to identify and develop such a specific biomarker for manganese-induced neuronal damage. By learning the molecular mechanism of cytotoxicity, one will be able to find a better way for prediction and treatment of manganese-initiated neurodegenerative diseases.

• 대한공업교육학회지
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• v.38 no.1
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• pp.49-67
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• 2013

The purpose of this study is to analyze the external systems and the units 'problem solving and invention' of the middle school technology and home economics 1 textbooks of the revised 2011 national curriculum in an effort to provide some information on the content system of invention education in technology class, as invention education was provided as part of a regular subject for the first time. The findings of the study were as follows: First, 'Technology and Inventions' chapter of Technology and Home Economics 1 Textbooks occupied 10-18% share, with the subchapter of 'Problem Solving and Invention' unit taking up 6.7-29% of the textbooks. Second, for most textbooks, 'Technological Problem Solving', 'Idea Generation' 'Multi-dimensional Projection Method', 'Expansive Thought-Processing Methodology', 'Converging Thought Methodology' and 'Invention in Everyday Lives' were included as main contents based on the accomplishment criteria presented in education process interpretation documents. Third, the detailed structures were generally made up as follows: Introduction (Broad Chapter Title, Subchapter Table of Contents, Introduction, Subchapter Title, Study Objectives, Open Thinking); Development (Unit Title, Thinking Ahead, Core Terms, Main Text, Study Helper, Activities, Research Exercises, Supplemental Readings, In-depth Study Topics, Technology in Everyday Lives, Reading Topics, Discussion Topics, and Career Helpers); and Summary (Subchapter Summary, Study Summary, Terms Summary, Writing Follow-up, Self Review, Broad Chapter Evaluation). Fourth, based on the analysis of figures included, photographs had the largest share, followed by figures, tables, and graphs. The photos were used to illustrate various inventions, invention methodologies, and exercise activities, while figures were included to depict the contents included in the main text, and the tables to assist to preparation of process diagrams or materials lists. Fifth, based on the analysis of content weights, greater weights were placed on 'Inventions and Thoughts', and 'Invention Experiment Activities,' while 'Understanding Inventions' and 'Invention and Patents' chapters did not have a lot of texts involved. Sixth, based on the analysis of content presentation methods, most textbooks combined figures, tables, illustrations and texts to discuss the topics. Based on the above study results, we suggest the following: First, a consistent education curriculum should be developed over the topic of invention; and second, more precise and systematic analysis of textbooks would need to be performed.

• Korean Security Journal
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• no.31
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• pp.73-100
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• 2012

Republic of Korea for the last 2012 nuclear security summit in Seoul in three days from March 26, has held great success. This industry watchers at home and abroad through professional meetings and private organizations to promote global nuclear security was intended to draw, for the preparation of this event the most important one of the things that should be addressed at the meeting was over the top guard. The national guard of heads of state and nationally significant as the important issues should be dealt with. So who is responsible for national security summit national guard for a successful guard against participants should have a higher understanding, these stories ever to be dealt with important security subjects is the psychological state of cognition. This study is currently a source of honor to escort the psychological state of subjects, and whether the search as I looked at cognition. Qualitative research methods to conduct research in-depth interview technique was used for one of the transcribed data analysis program, a non-quantitative data were analyzed using NVivo 8. As a result of this study, analysis of the problem compared with the usual methods 39 (72.2%), fine-grained observation and 15 (27.7%), through the media how cognition 41 (73.2%), marginal help of 15 (26.7%) were. The usual comparison with how honored Issue sources to detect security of those words and actions and facial expressions, etc. Security of subjects over the state of mind cognition that he, detailed observation of the national guard to security subjects the psychological state of cognition which are pre-Thorough Information subjects that can have all the information about security and the state can be obtained by saying that. Media coverage through a cognitive approach national guard of the media coverage to understand the security subjects of the political situation to understand the prerequisite that were marginal for help through the cognitive approach of security subjects surrounding the execution of security workers, Secretary in charge of protocol and security, and be propagated through the selection techniques to be utilized was that.

• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.399-406
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• 2000

The effect of inlay surface treatment on bonding was investigated when resin inlay was bonded to resin-modified glass-ionomer base with resin cement. For the preparation of glass-ionomer base, resin-modified glass-ionomer cement (Fuji II LC, GC Co., Japan) was filled in class I cavities of 7mm in diameter and 2mm in depth made in plastic molds. Eighty eight resin inlay specimens were made with Charisma$^{(R)}$ (Kulzer, Germany) and then randomly assigned to the four different surface treatment conditions: Group I, $50{\mu}m$ aluminium oxide sandblasting and silane treatment ; Group II, silane treatment alone ; Group III, sandblasting alone, and Group IV (control), no surface treatment. After a dentin bonding agent with primer (One-Step$^{TM}$, Bisco Inc., IL., U.S.A.) was applied to bonding surface of resin inlay and base, resin inlay were cemented to glass-ionomer base with a resin cement (Choice$^{TM}$, Bisco Inc., IL., U.S.A.). Shear bond strengths of each specimens were measured using Instron universal testing machine (4202 Instron, lnstron Co., U.S.A.) and fractured surfaces were examined under the stereoscope. Statistical analysis was done with one-way ANOVA and Dunkan's multiple range test. The results were as follows: 1. Sandblasting and silane treatment provided the greatest bond strength(10.56${\pm}$1.95 MPa), and showed a significantly greater bond strength than sandblasting alone or no treatment (p<0.05). 2. Silane treatment provided a significantly greater bond strength(9.77${\pm}$2.04 MPa) than sandblasting alone or no treatment (p<0.05). However, there was no significant difference in bond strength between sandblasting treatment and silane one (p>0.05). 3. Sandblasting alone provided no significant difference in bond strength from no treatment (p>0.05). 4. Stereoscopic examination of fractured surface showed that sandblasting and silane treatment or silane treatment alone had more cohesive failure mode than adhesive failure mode. 5. In relationship between shear bond strength and failure mode, cohesive failure occurred more frequently as bond strength increased.

• 대한공업교육학회지
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• v.41 no.1
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• pp.68-87
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• 2016

This research conducted a survey for total 166 teachers of schools so as to analyze validity and satisfaction for performance objectives of SMB administration subsidy the HRDP and the CEP in Specialized High School. The results of research are as follows. First, teachers recognize that purpose of HRDP is to expand employment of specialized high school and provide human resource of SMB. And, they recognize that HRDP is important to improve school outcomes and makes a positive effect on the improvement of school outcomes. Second, teachers recognize that objectives of HRDP are improvement of student's understanding for SMB, improvement of teacher's understanding for SMB, improvement of SMB's understanding of school, cultivation of student's occupational view, systematization of career guiding program based on employment process, strengthening of industry-academia cooperation education, improvement of the level of student's skill, fulfillment of workplace experience and practice focusing workplace learning, training of customized human resource for SMB, improvement of student's adaptation to the workplace, improvement of employment rate for SMB, expansion of job opportunities for students with SMB, preparation of the base of connection between school and SMB, publicity of school, expansion of opportunities to cooperate between SMB and school, establishment of cooperative system among industrial association and school, introduction and operation of the employment connective model for joint education and employment, strengthening of field professionalism of teachers. However, satisfaction for the achievement of objectives of HRDP except for strengthening of industry-academia cooperation education and improvement of employment rate for SMB is relatively lower than the validity. Third, teachers in charge of human resource training business of middle and small sized company's specialized high school recognize that objectives of CEP are expansion of job opportunities for students with SMB, excavation of good-quality SMB, expansion of opportunities to cooperate between SMB and school, fulfillment of workplace learning, improvement of student's major foundation and in-depth skill, improvement of literacy, math, teamwork and communication abilities for students' job performance, improvement of student's working attitude and student's proper career exploration decision. However, satisfaction for achievement of objectives of CEP is relatively lower than the validity.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.3-4
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• 2000

Many researchers are interested in the synthesis and characterization of carbon nitride and diamond-like carbon (DLq because they show excellent mechanical properties such as low friction and high wear resistance and excellent electrical properties such as controllable electical resistivity and good field electron emission. We have deposited amorphous carbon nitride (a-C:N) thin films and DLC thin films by shielded arc ion plating (SAIP) and evaluated the structural and tribological properties. The application of appropriate negative bias on substrates is effective to increase the film hardness and wear resistance. This paper reports on the deposition and tribological OLC films in relation to the substrate bias voltage (Vs). films are compared with those of the OLC films. A high purity sintered graphite target was mounted on a cathode as a carbon source. Nitrogen or argon was introduced into a deposition chamber through each mass flow controller. After the initiation of an arc plasma at 60 A and 1 Pa, the target surface was heated and evaporated by the plasma. Carbon atoms and clusters evaporated from the target were ionized partially and reacted with activated nitrogen species, and a carbon nitride film was deposited onto a Si (100) substrate when we used nitrogen as a reactant gas. The surface of the growing film also reacted with activated nitrogen species. Carbon macropartic1es (0.1 -100 maicro-m) evaporated from the target at the same time were not ionized and did not react fully with nitrogen species. These macroparticles interfered with the formation of the carbon nitride film. Therefore we set a shielding plate made of stainless steel between the target and the substrate to trap the macropartic1es. This shielding method is very effective to prepare smooth a-CN films. We, therefore, call this method "shielded arc ion plating (SAIP)". For the deposition of DLC films we used argon instead of nitrogen. Films of about 150 nm in thickness were deposited onto Si substrates. Their structures, chemical compositions and chemical bonding states were analyzed by using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and infrared spectroscopy. Hardness of the films was measured with a nanointender interfaced with an atomic force microscope (AFM). A Berkovich-type diamond tip whose radius was less than 100 nm was used for the measurement. A force-displacement curve of each film was measured at a peak load force of 250 maicro-N. Load, hold and unload times for each indentation were 2.5, 0 and 2.5 s, respectively. Hardness of each film was determined from five force-displacement curves. Wear resistance of the films was analyzed as follows. First, each film surface was scanned with the diamond tip at a constant load force of 20 maicro-N. The tip scanning was repeated 30 times in a 1 urn-square region with 512 lines at a scanning rate of 2 um/ s. After this tip-scanning, the film surface was observed in the AFM mode at a constant force of 5 maicro-N with the same Berkovich-type tip. The hardness of a-CN films was less dependent on Vs. The hardness of the film deposited at Vs=O V in a nitrogen plasma was about 10 GPa and almost similar to that of Si. It slightly increased to 12 - 15 GPa when a bias voltage of -100 - -500 V was applied to the substrate with showing its maximum at Vs=-300 V. The film deposited at Vs=O V was least wear resistant which was consistent with its lowest hardness. The biased films became more wear resistant. Particularly the film deposited at Vs=-300 V showed remarkable wear resistance. Its wear depth was too shallow to be measured with AFM. On the other hand, the DLC film, deposited at Vs=-l00 V in an argon plasma, whose hardness was 35 GPa was obviously worn under the same wear test conditions. The a-C:N films show higher wear resistance than DLC films and are useful for wear resistant coatings on various mechanical and electronic parts.nic parts.

• Clean Technology
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• v.27 no.4
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• pp.359-366
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• 2021

Halloysite nanotubes (HNTs), the multiwalled clay mineral with the composition of Al₂Si₂O₅(OH)₄·nH₂O, have been highlighted as a low-cost adsorbent for the removal of dyes from wastewater. Although a powder of halloysite presents a high specific surface area, forming media are significantly considered due to sludge-clogging induced by the water-bound agglomeration. However, higher firing temperature to achieve the structural durability of the media and lower utilization rate due to longer penetration depth into the media act as hurdles to increase the dye-adsorption capacity. In this work, the retention of the adsorption capacity of halloysite was evaluated with methylene blue solution after the heat treatment at 750 ℃. In order to improve the utilization rate, tubular media were fabricated by extrusion. The images taken by transmission electron microscopy show that HNTs present excellent structural stability under heat treatment. The HNTs also provide superb capacity retention for MB adsorption (93%, 18.5 mg g^-1), while the diatomite and Magnesol^® XL show 22% (7.65 mg g^-1) and 6% (11.7 mg g^-1), respectively. Additionally, compositing with lignin enhances adsorption capacity, and the heat treatment under the hydrogen atmosphere accelerates the adsorption in the early stage. Compared to the rod-type, the tubular halloysite media rapidly increases methylene blue adsorption capacity.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.14 no.3
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• pp.59-71
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• 2019

The domestic unemployment rate is now seriously increasing due to the impact of the international trend of incurring high costs using only a small number of manpower in a situation where the business has been being reduced in size. The nation is taking start-up promotion policies as a way to overcome the problem, but with the advent of excessive entrepreneurs and their concentration on specific areas, their survival is in an unclear situation. Thus, this study was intended to provide a useful direction for successful start-ups by identifying the impact of entrepreneurial motivation and entrepreneurship, internal characteristics of entrepreneurs, and of competency characteristics, external characteristics of them, on sustainability through business performance. Thus, the purpose of this study was to provide a useful direction for successful start-ups by identifying the impact of entrepreneurial motivation and entrepreneurship, internal characteristics of entrepreneurs, competency, and external characteristics, on sustainability through business performance. The result of verifying the hypothesis has showed that entrepreneurial motivation, entrepreneurship, and competency characteristics had a positive effect on business performance, and on the other hand, the business performance had a positive effect on sustainability. In addition, in terms of the impact of entrepreneurial motivation, entrepreneurship, and competency characteristics on sustainability, all of them had mediating effects on business performance. It is obvious that studies on the factors affecting business performance and corporate sustainability up to now have been carried out by only collecting the independent variables of this study individually or two of them. so it is judged that if the study, which has verified the practical direction in general through the verification of entrepreneurs's internal and external characteristics from various angles, is performed more comprehensively along with the addition of background characteristics of entrepreneurs, such as characteristics of start-up preparation, etc., in the future, more in-depth results will be able to be obtained.

• Journal of the Korean Chemical Society
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• v.66 no.4
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• pp.323-332
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• 2022

The purpose of this study is to investigate the effects of science classes using smart devices that combine augmented reality (AR) and virtual reality (VR) on the scientific attitude of middle school gifted students. In addition, it is intended to find out the perception of science classes using these smart devices. In addition to actual experiments, a science class program that allows students to experience science experiments virtually using AR and VR was applied to 15 middle school gifted students. Before and after the application of the program, the questionnaire is to investigate the interest in scientific classes, the attitude toward science exploration, and the professional interest in science, and the recognition of classes that combine AR and VR. In addition, through in-depth interviews, the perceptions of gifted students was accurately investigated. As a result of this study, the content of science classes and instructors showed high class satisfaction, but the smart devices and applications used during the science classes showed lower class satisfaction than others. As a result of comparing and analyzing the pre-post of gifted students, interest in science class, attitude toward science inquiry, and professional interest in science increased significantly among the sub-areas of the scientific attitude test. As a result of analyzing free responses and indepth interviews, gifted students responded with the advantage that classes using smart devices that combine AR and VR can be tested quickly and safely for a short time compared to actual experiments. On the other hand, they responded with low completeness of the application and dizziness when operating virtual reality. Based on this, implications for the development of applications and instructional programs using advanced technologies that can experience realistically limited scientific experiments such as experimental preparation, class time, and risk factors were obtained.