• Title, Summary, Keyword: Engineering education

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Physicochemical Properties and Distribution of Heavy Metals in Stream Sediments of the Daejeon Area (대전지역 주요하천 하상퇴적물의 물리화학적 특성 및 중금속 분포)

  • Jeong, Chan-Ho;Lee, Sang-Gu
    • Journal of the Mineralogical Society of Korea
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    • v.19 no.4
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    • pp.259-264
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    • 2006
  • This work carried out to analyze the physicochemical properties and investigate the assessment of heavy metal contamination of stream sediments of the Yudeung and the Gab streams in the Daejeon area. The pH of stream sediments of the Yudeung stream shows the range of weak acid and weak alkaline. Most of stream sediments contain about 80% sand grain and have low water and cation retention capacity. Hence the stream sediments are not suitable fur various plans to grow up. The analysis of heavy metals in the stream sediments shows that the concentration of Pb, Cr and Cd increases from upstream to down stream. It is likely that the trend has a relationship with the water. Contamination of stream water. The authors recommend that clay materials be replenished in the stream sediments to increase the self-purification capacity and to make the suitable condition for growing up of various plants, and that water quality of the stream which can Influence into the contamination of stream sediments be monitored.

A study on Protection Coordination Method for Electric Vehicle Charging Facility based on the Wireless Power Transmission (무선전력전송 전기충전설비용 전원공급장치의 최적운용방안에 관한 연구)

  • Ryu, Kyung-Sang;Kim, Byungki;Kim, Dae-Jin;Jang, Moon-Seok;Rho, Daeseok;Ko, Hee-Sang
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.9
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    • pp.42-51
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    • 2017
  • This paper deals with the power supply facility providing wireless power transmission for a type of electric vehicles called the on-line electric vehicle(OLEV) and proposes optimal protection coordination methods which analyze the faultsin the 60Hz and 20kHz bands using PSCAD/EMTDC, which is the typical commercial software for the distribution system. The simulation results show that the proposed methods can reduce the fault current by introducing an NGR (Neutral Ground Resistor) in the 60Hz band and prevent the malfunctioning of the protection device by installing a CT in the neutral wire in the 20kHz band when a ground fault occurs.

A Study on the Characteristics of Open Access in Korean Scholarly Journals: Focused on KCI Journals (국내 학술지의 오픈액세스 특성에 관한 연구: KCI 등재지를 대상으로)

  • Kim, Gyuhwan;Joung, Kyoung Hee
    • Journal of the Korean Society for information Management
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    • v.34 no.3
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    • pp.251-267
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    • 2017
  • This study aimed to analyze open access features of 1,890 Korean scientific journals registered in the Korea Citation Index (KCI). To this end, this study classified open access features of the target scientific journals into two main aspects, free access and free redistribution. The analysis results indicated that the target scientific journals had strong free access aspects. Based on websites, 67% of the target scientific journals allowed for free access without a login process and based on free database, 48% provided free access. On the other hand, the target scientific journals had weaker free redistribution aspects compared to their free access aspects. Only 14% of them offered the CC (creative commons) license. Another finding was that there were clear differences in open access aspects by academic field. Medicine, pharmacy, natural science, agriculture, fisheries, oceanography, and engineering had stronger open access aspects than humanities, sociology, arts, physical education, and interdisciplinary science. It appears that the difference was caused by the presence or absence of organizations supporting distribution of scientific journals of the fields concerned. To narrow the gap, it is recommended that the open access governance system is established to set up open access policies for Korean scientific journals regardless of academic fields and to support them.

Bone-level implants placed in the anterior maxilla: an open-label, single-arm observational study

  • Gao, EnFeng;Hei, Wei-Hong;Park, Jong-Chul;Pang, KangMi;Kim, Sun Kyung;Kim, Bongju;Kim, Soung-Min;Lee, Jong-Ho
    • Journal of Periodontal and Implant Science
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    • v.47 no.5
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    • pp.312-327
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    • 2017
  • Purpose: This study assessed marginal bone remodeling and soft tissue esthetics after the loading of single bone-level implants in the anterior maxilla. Methods: An open, single-arm observational clinical trial with 3 years of follow-up was performed, including 22 implants. The patients presented with a single tooth gap in the anterior maxilla (tooth positions 14-24), with natural or restored adjacent teeth. An implant was placed at least 8 weeks post-extraction and healed submerged for 6 weeks. After the second-stage operation, a fixed provisional prosthesis was provided. The final restoration was placed 6 months after the provisional restoration. The time of the provisional crown connection was considered to be the baseline in this study. Esthetic parameters and the marginal bone level were assessed at 6, 12, 24, and 36 months. Results: All implants were well integrated in the bone. A statistically significant increase was found in the mean implant stability quotient between the time of the provisional prosthesis and the time of the final prosthesis. Most implants (95.5%) revealed marginal bone resorption (<0.5 mm), and just 1 implant (4.5%) showed a change of 2.12 mm from baseline to 36 months (mean $0.07{\pm}0.48mm$), while the crestal bone level decreased significantly, from $2.34{\pm}0.93mm$ at baseline to $1.70{\pm}1.10mm$ at 36 months. The facial gingival margin and papilla were stable and the esthetic scores indicated high patient and dentist satisfaction. Conclusions: Platform-switching bone-level implants placed in maxillary single-tooth gaps resulted in successful osseointegration with minimal marginal bone resorption. The peri-implant soft tissue was also esthetically satisfying and stable.

Research on Reduction and Recycling of Food Waste by Separating Raw Food Waste and Earth Worm Composting in the Apartment (공동주택의 음식물 생쓰레기 분리배출과 지렁이퇴비화를 이용한 음식물쓰레기 감량 및 자원화 모델 연구)

  • Choi, Kwang-Soo
    • Journal of Environmental Science International
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    • v.20 no.1
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    • pp.137-146
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    • 2011
  • In this research, food waste source reduction model for apartment was investigated. In spite of prohibition of direct landfill of food waste and continuous efforts made by government and local government, food waste production increases steadily. Recycling ratio of the food waste increases every year, but its products have many problems like low quality, stability, salt, odor etc. Household occupies 63.3% of whole food waste production and this is subject to be a key factor to control food waste. We surveyed S apartment in Kwangju city as a model case, in which administrative office and women's association adopted clean plate eating, separation of raw food waste and earth worm composting as a series of method for source reduction and recycling inside the apartment. With the help of residents' participation and practice, food waste production decreased 15.6% from 0.31 g/capita/day in 2007 to 0.26 g/capita/day in 2009 (domestic average 0.30 g/capita/day). Separation of raw food waste and its composting using earth worm were very effective, and were subject to resolve the problems of present food waste treatment technologies. And earth worm composting was very useful in environmental, economical, societal and educational aspects. Instead of economical incentive, educational programs about food value, environmental problem and critical method for food waste separation were more effective for promotion of source reduction. From the analyses on the process and success factors in this model, we could conclude that leader's role was one of the key factors for the settlement of source reduction, and that was to understand the seriousness of the food waste and to seek solution, to test techniques, and to practice by oneself. Furthermore, networking and collaboration among residents, local government, NGO and local press promoted residents' participation, and it was through various education and investigation. Finally, source reduction and self recycling model of food waste in the apartment, that applies separating raw food waste and earth worm composting based on the collaboration among residents, local government, NGO, and local press, should be disseminated, and environmental policy also should be changed to make it possible.

A study on the Correlation between Key Competencies and Teacher Efficacy of Pre-service Industrial Teachers (예비 공업교사의 직업기초능력과 교사효능감과의 상관관계 연구)

  • Lee, Kyu-Nyo;Kim, So-Yeon;Park, Ki-Moon
    • 대한공업교육학회지
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    • v.36 no.2
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    • pp.181-199
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    • 2011
  • The purpose of this study is to determine the level of key competencies and teacher efficacy of pre-service industrial teachers as related to their personal backgrounds, and to analyze the correlation between personal variables, key competencies and teaching efficacy. This will be provided as basic resources for pre-service teacher training program to improve the understanding of key competencies and teaching efficacy of pre-service industrial teachers. The results of this study are as follows. First, the teacher efficacy of pre-service industrial teachers was found to be above average (M=3.0), and teaching efficacy (M=3.41) was found to be a bit higher than personal teacher efficacy (M=3.28). Upon analyzing the significant differences of teacher efficacy resulting from background variables, it was found that gender and major had no difference while the effect of school year on teaching efficacy of teacher efficacy showed statistically significant differences. Second, the lower regions of key competencies of pre-service industrial teachers all were above the average 3.0. Gender and school year were exhibited no significant difference, and only the global competence of key competencies showed significant difference. Third, it was found that the gender and major of pre-service industrial teachers had no correlation with teacher efficacy and key competencies. On the other hand, school year variable showed significant positive correlation with teacher efficacy (r=.274) and key competencies (r=.168). Lastly, it was found that key competencies and teacher efficacy had positive correlation of r=.475.

Development of Traffic Safety Behavioral Index on Elementary School Children (초등학교 어린이 교통안전 행동지수 검사도구 개발연구)

  • Hwang, Dae-Chul;Choi, Beom-Seok
    • International Journal of Highway Engineering
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    • v.13 no.4
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    • pp.187-198
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    • 2011
  • Researches on children's traffic behavior have only focused on traffic accidents and the number of accidents, and therefore it's been impossible to deal with more broad field of study. In this research we can review the possibility of traffic accidents of children and provide them with traffic education. The goal of this research is to develop a device for measuring possibility of children in terms of traffic behavior. Around 600 elementary students of two schools involved in the pretest with 259 questions and about 3,500 students(junior level 53 questions & senior level 72 questions) involved in practical test. At the result of the research, junior level extracted 4 factors(Lack of behavioral control, Aggressive, Self-regulation, Impulsive Instinct) and 44 questions, and senior level extracted 4 factors(Lack of behavioral control, Depression, Sense-oriented, Aggressive) and 69 questions. We take the gender consideration in separate the groups whether the group has traffic behavioral problem or not. In these series of research, we got the standard score such as junior male student, 63 & female student, 50 and senior male student, 110 & female student, 99.

A Service Framework for Supporting XML-based National Research and Development Report Contents (XML 기반 국가연구개발보고서 콘텐츠 서비스의 프레임워크 설계)

  • Shon, Ho-Sun;Lee, Jong-Yun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.1
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    • pp.427-435
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    • 2011
  • The information management system for the national R&D reports on the level of each government department have been operated in order to have special affiliated organizations collect detailed information, construct databases for R&D reports, and operate their information system; thus, the current classification system for the R&D reports on the governmental level is insufficient. Also, each department requires to prepare a standardized electronic original text service system since mutually different electronic original text services have been provided. therefore, this paper sets up the following research goals and detailed research contents. The goals of this study are to establish methods to standardize the forms of national R&D reports and suggest the framework for XML-based national R&D reports services by analyzing the problems in the forms of previous national R&D reports services. As detailed research contents, first, Identify the current R&D electronic original reports services by each government department. Second, this paper analyzed primary overseas science technology information service systems related with national research and development reports and related database schemata. this paper proposed the XML-based national R&D reports service framework through analyzing the problems in the framework of the existing national R&D reports service system and also established and suggested the methods to provide database schema design and report portal services. Lastly, it is expected that this paper will have academic contribution to enhancing R&D investment efficiency by utilizing collaboratively the information and resources related with national R&D through establishing the general information management system for national-dimension R&D reports and also managing science technology information efficiently and developing a user-centered integrated information system.

Changes of Microbial Load on the Hands of Food Preparers (손의 미생물 오염도의 경시적 변화 - 조리종사자를 중심으로)

  • Kim, Jong-Gyu;Park, Jeong-Yeong;Kim, Joong-Soon
    • Journal of Food Hygiene and Safety
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    • v.26 no.2
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    • pp.154-159
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    • 2011
  • Inadequate food handling and poor hand hygiene playa major role in the occurrence of foodborne diseases. The objective of this study was to find out if the level of microbial contamination on the hands of food preparers varies by time during their working period. This study focused on the contamination of aerobic plate count, total and fecal coliforms, Escherichia coli, Staphylococcus aureus, and Salmonella spp. Sampling from left hand and right hand of twenty food preparers was done with glove-juice method at every two hours during their work. Microbiological testing was conducted according to the Food Code of Korea. The microbiological load on the hands was changed over time. Samples taken from their hands before work and at 8 hours showed higher levels of bacteria than those taken at 2, 4, and 6 hours during work and/or after work (p < 0.05). The contamination levels of microorganisms were consistently higher in right hand than in left hand. Poor hand hygiene practices were indicated by the positive results for total and fecal coli forms, E. coli, S. aureus, and Salmonella spp. on the hands of some food preparers. This study indicates food preparers' hands can be a vehicle of pathogen during their work. The results of this study emphasize the importance of hand hygiene education and training targeting the food preparers.

Policy Model for Securing and Utilizing Foreign Brains - focusing on the Higher Education - (외국인 인재 유치 및 활용을 위한 정책 모형 연구 - 고등교육기관을 중심으로 -)

  • Shin, Jun-Woo;Kwon, Jang-Woo;Lee, Jung-Mann
    • The Journal of the Korea Contents Association
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    • v.10 no.3
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    • pp.423-435
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    • 2010
  • The number of professionals in the science and engineering fields decreases all over the world. Especially in Korea, the declining rate of both the laborable and economically active population, aging of the population at the fastest level, and the declining birth rate make it tougher to secure the core brains of the future. After speculation of all programs above, some common factors have been derived and every program appeared to have the support for each level of inducing, caring, and utilizing. And the means of support could be categorized into the financial, legal, and social aspects. Lastly, a logical tool called Systems Thinking has been applied to the FLS Conditions and the Brain Internalization Process to assure the efficacy and applicability of the models. This is to minimize any de facto side effects by analyzing all 'feedback loops' stemming from the models. And the 'causal loop diagrams' have been utilized to come with the complementary measures. Such series of verification could convince the virtue of the models. Governments and universities can make use of the FLS Conditions and the Brain Internalization Process so the policies or plans about the foreign brains can be built in a uniformized and consistent framework. I hope, as a result, the international competency of Korea to induce and utilize the foreign brains be raised with the constant and standardized formality.