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Modeling of unilateral effect in brittle materials by a mesoscopic scale approach

  • Pituba, Jose J.C.;Neto, Eduardo A. Souza
    • Computers and Concrete
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    • v.15 no.5
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    • pp.735-758
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    • 2015
  • This work deals with unilateral effect of quasi-brittle materials, such as concrete. For this propose, a two-dimensional meso-scale model is presented. The material is considered as a three-phase material consisting of interface zone, matrix and inclusions - each constituent modeled by an appropriate constitutive model. The Representative Volume Element (RVE) consists of inclusions idealized as circular shapes randomly placed into the specimen. The interface zone is modeled by means of cohesive contact finite elements developed here in order to capture the effects of phase debonding and interface crack closure/opening. As an initial approximation, the inclusion is modeled as linear elastic as well as the matrix. Our main goal here is to show a computational homogenization-based approach as an alternative to complex macroscopic constitutive models for the mechanical behavior of the quasi-brittle materials using a finite element procedure within a purely kinematical multi-scale framework. A set of numerical examples, involving the microcracking processes, is provided. It illustrates the performance of the proposed model. In summary, the proposed homogenization-based model is found to be a suitable tool for the identification of macroscopic mechanical behavior of quasi-brittle materials dealing with unilateral effect.

Environmental Impact on the KEPCO 765-kV Double Circuit Transmission Line (한전 765 kV 2회선 송전선로의 전기환경장애 특성)

  • Lee, D.I;Sin, K.Y;Kim, J.B
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.2
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    • pp.117-126
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    • 1999
  • The environmental impact of the KEPCO 765-kV transmission line was studied using a full scale test line in order to develop the design technology. Therefore this paper describes an environmental design summary of the audible noise, hum noise, wind noise, radio interference, TV interference and electric field measurement from the KEPRI 765-kV double circuit transmission test line with a bundle of $6-480mm^2$ conductors per phase. The analysis of the test results shows that 6-Rail and 6-Cardinal conductors bundle satisfy the audible noise criterion & TV interference under the stable rainy weather condition and the radio interference level under the fair weather. And the other items are also agreed with the design level criterion for KEPCO 765-kV transmission line.

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Influence of Family-friendly Corporate Environment on Women Managers' Self-efficacy and Career Success (가족친화적 기업환경이 여성관리자의 자아효능감과 경력성공에 미치는 영향)

  • Kim, Phil-Suk
    • Journal of Families and Better Life
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    • v.30 no.4
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    • pp.49-57
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    • 2012
  • This study aims examining a few elements representing a family-friendly corporate environment such as the attitude of CEOs, corporate culture, the support from direct supervisors and their influence on the sense of self-efficacy and career success of women managers. The summary and conclusion of the result of this study is as follows; first, the positive attitude of CEOs as one of the representing elements for family-friendly corporate environment was found to affect the sense of self-efficacy and the career success of married women managers with positive effects. Second, the support of superiors turned out to have a positive effect on career development of women managers. Finally, the sense of women's self-efficacy turned out to affect career success of women managers. For the use of female resources as a growth power, the attitude of CEOs who promote gender equality, and the support of supervisors will play a very important part, and in order to build a corporate culture with gender equality, promotion and policy-making on corporate as well as government level are required.

A Study on Korean Science Teachers' Points of View on Nature of Science (과학교사들의 과학의 본성에 관한 관점 조사)

  • Cho, Jung-Il;Ju, Dong-Ki
    • Journal of The Korean Association For Science Education
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    • v.16 no.2
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    • pp.200-209
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    • 1996
  • Recent literature in science education has emphasized nature of science in science teaching. The theme has been considered to be an important element for scientific literacy.The purpose of this study was to identify Korean science teachers' points of view on topics related to nature of science, such as definition of science, characteristics of scientific hypotheses, scientific theories and scientific laws, and their construction, scientists, and scientific methods. The relevant 13 items were selected from Views on Science-Technology-Society (VOSTS) by the authors for this study. Most teachers perceived science as an exploratory process or problem solving. Some perceived science as an application of knowledge to make this world a better place to live in. Teachers viewed scientific activities as scholastic and individualistic instead of pragmatic or collective. They did not hold clear understandings of the idea that scientific knowledge is subject to change. As identified in previous studies, teachers thought that scientific ideas develop from hypothesis to theories, and finally to scientific laws. They did not show sound understanding of inventiveness of scientific hypotheses and theories, nor discovery of scientific laws. In summary, teachers' major points of view reflected 'realism'. It suggested that they needed to understand nature of science in the ways which it has been described in recent literature of science education, in order to teach science with personal and social contexts.

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A Study on the Mothers' Level of Consumer Socialization Influencing the Children's Level of Consumer Skills (어머니의 소비자사회화수준이 자녀의 소비자기능에 미치는 영향에 관한 연구)

  • 문숙재
    • Journal of the Korean Home Economics Association
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    • v.27 no.4
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    • pp.105-122
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    • 1989
  • The purpose of this study is to provide the basic data to analyze the importance of family as the consumer socialization agents influencing consumer socialization and to enhance the adolescent children's level of consumer skill. The summary of research results is as follows: 1. There were significant differences in the mothers' level of consumer socialization according to the age, education level, consumer attitude, children's grade. 2. The factors showing significant relations to children's level of consumer skills were found to be children's sex, their grade, mother's age and their consumer attitude. The similar results were found for the various aspects of consumer skills. 3. Both the mother's level of consumer socialization with respect to themselves and with respect to children were found to be positivily correlated to children's level of consumer skills. 4. The result of analyzing the independent contribution of the factors in affecting the childern's level of consumer skills is that in order of increasing contribution the factors are the mother's level of consumer socialization with respect to children, children's grade, their sex, the mother's age. 5. The mother's level of consumer socialization with respect to themselves and with respect to children were found to be considerably influenced by demographics and socio-psychological variables. And it was confirmed that the mother's level of consumer socialization has causal relations to children's level of consumer skills.

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Influences of Various Electrolytes on the Low-Temperature Characteristics of Ni-MH Secondary Battery (Ni-MH 2차 전지의 저온특성에 미치는 전해액의 영향)

  • Park, Chae-Gyu;Shim, Jong-Su;Jang, Min-Ho;Park, Choong-Nyeon;Choi, Jeon
    • Journal of Hydrogen and New Energy
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    • v.18 no.3
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    • pp.284-291
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    • 2007
  • The Ni-MH batteries for HEV and industry are normally placed in outdoor, consequently causing an too weak discharge power problem due to a cold weather specially in winter time. In order to improve the low temperature performances of the Ni-MH battery for HEV and industrial uses, it has been investigated the low temperature discharge characteristics of Ni-MH battery with various electrolytes at $-18^{\circ}C$. The summary of experimental results are as follows. The low temperature characteristics depended strongly on the characteristics of electrolytes. When the concentration of the electrolytes were too high or too low the low temperature performance was poor. The best electrolyte was composed of KOH 6.2M+LiOH 1.2M. An addition of RbOH or CsOH to electrolyte improved the low temperature performance. The best total concentration of electrolyte composed of KOH, NaOH and LiOH was about 7M.

An Analysis of the Determinants of Consumers' Perceived Medical Service Quality and Complaining Behavior (소비자들이 지각한 의료서비스 품질결정요인과 불만호소행동 특성 분석 -인천, 부천 지역을 중심으로-)

  • 강이주
    • Journal of the Korean Home Economics Association
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    • v.35 no.2
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    • pp.217-234
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    • 1997
  • This study attempts to analyze some determinants of consumers' medical service quality and their complaining behavior. The results can be summerized as follows: 1. The determinants of consumers' perceived medical service quality could be categorized as five factors; i.e. nursery, hospital environment, medical doctors, other staffs service fee. Among them nursery sector consists of 32% variance. 2. According to the discriminant analysis, those determinants are of great value to distinguish between satisfied/unsatisfied group. The hit ratio was 85.4% which is relatively high score. 3. The type of complaining behavior could be grouped into no action, private and public complaining behavior. Most of respondents belonged to no action group and a few showed private complaining behavior. Any respondents who were willing to show public complaining behavior could not be found out. 4. These variables which influence complaining behavior were preconception toward hospital, barrier to complaining process and expected complaining behavior. Among them the first one was most influential variable. 5. In order to distinguish between complaining/non complaining behavior group, discriminant analysis was done. The result showed the above three variables had a significantly discriminatory power, the hit ratio reaching above 70%. In summary, we can see that consumers' evaluation on the whole medical service depends on the external factor such as staffs' attitude or hospital facilities due to the lack of their ability to evaluate highly specialized service like doctor's treatment.

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Analytical similitudes applied to thin cylindrical shells

  • De Rosa, Sergio;Franco, Francesco
    • Advances in aircraft and spacecraft science
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    • v.2 no.4
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    • pp.403-425
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    • 2015
  • This work is focused on the definition and the analysis of both complete and incomplete similitudes for the dynamic responses of thin shells. Previous numerical and experimental investigations on both structural and structural-acoustic systems motivated this further analysis, mainly centred on the incomplete (distorted) similitudes. These similitudes and the associated scaling laws are defined by using the classical modal approach (CMA) and by invoking also the Energy Distribution Approach (EDA) in order to take into account both the cinematic and energetic items. The whole procedure is named SAMSARA: Similitude and Asymptotic Models for Structural-Acoustic Research and Applications. A brief summary of the procedure is herein given and the attention is paid to the analytical models of thin stiffened and unstiffened cylindrical shells. By using the well-known smeared model, the stiffened cylinder equations are used as general framework to analyse the possibility to define exact (replicas) or distorted similitudes (avatars). Despite the extreme simplicity of the proposed models, the results are really encouraging. The final aim is to define equivalent models to be used in laboratory measurements.

Parenting Stress with her Infant and Social Support and Parenting Efficacy of Mother who commit their infants to child-care facilities (보육시설 영아반에 자녀를 보내는 어머니의 양육 스트레스 및 사회적 지지와 양육 효능감)

  • Ryu, Ki Ja;Kim, Young Joo;Song, Yeon Sook
    • Korean Journal of Childcare and Education
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    • v.5 no.1
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    • pp.1-23
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    • 2009
  • The purpose of this study was to investigate mother's parenting stress with her infant and social support and parenting efficacy. The object of the study were 234 mothers who commit their infant to 10 child-care facilities in U metropolitan city. The method of research was questionnaire method. Followings are the summary of it ; The mother's parenting efficacy was generally high. Regression analysis was carried out to investigate the relative influence of the factors related to the mother's parenting efficacy. The variables that influence the mother's parenting efficacy were the social support, the parenting stress, the mother's age, the mother's academic background, income and the order of birth etc.

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SUMMARY OF THE RESULTS FROM THE PHEBUS FPT-1 TEST FOR A SEVERE ACCIDENT AND THE LESSONS LEARNED WITH MELCOR

  • Park, Jong-Hwa;Kim, Dong-Ha;Kim, Hee-Dong
    • Nuclear Engineering and Technology
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    • v.38 no.6
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    • pp.535-550
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    • 2006
  • The objectives of this paper are twofold to summarize the new findings and confirmed results from the Phebus FPT-1 experimental data and to report useful information to MELCOR users regarding the better use of MELCOR. For the core damage behavior, the early stage of a melt progression was predicted well; however, the late phase models, concerned with fuel dissolution, oxide cladding failure, fuel slumping, rubble debris heat up, effects of burn-up fuel, and so on, still showed limitations in MELCOR. For the fission product behavior, the comparison showed unexpected phenomena, various limitations, unresolved issues, and even absence of models. The issues summarized in this study have revealed the main areas where our endeavors need to be intensified in order to improve our understanding of severe accident phenomena. From the analysis of the Phebus FPT-1 test results, not only new core damage features, such as foaming or core expansion, but also possible new fission product release patterns due to effects from a high burn-up fuel have raised alternative challenging phenomena that should be solved in the next severe accident research phase.