• Title/Summary/Keyword: Interaction Coefficient

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Effects of flange and web slenderness ratios on elastic flange local buckling of doubly symmetric I-girders (이축 대칭 I형 거더의 플랜지 탄성좌굴에 대한 플랜지와 복부판 세장비의 영향)

  • Lee, Jeong-Hwa;Lee, Kee-Sei;Byun, Nam-Joo;Kang, Young-Jong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.8
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    • pp.456-464
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    • 2016
  • Increasing the strength of structural materials allows their self-weight to be reduced and this, in turn, enables the structures to satisfy esthetic requirements. The yield strength of high-performance steel is almost 480 MPa, which is approximately 50% higher than that of general structural steel. The use of high strength materials, however, makes the sections more slender, which can potentially result in significant local stability problems. The strength of slender element sections might be governed by their elastic buckling behavior, and the elastic buckling strength is very sensitive to the boundary conditions. Because the web provides the boundary conditions of the compressive thin-flange, the stiffness of the web can affect the elastic buckling strength of the flange. In this study, therefore, the effects of the flange and web slenderness ratios on the elastic flange local buckling of I-girders subjected to a pure bending moment were evaluated by finite element analysis (FEA). The analysis results show that the elastic local buckling strength and buckling modes were affected not only by the web support conditions, but also by the flange and web slenderness ratios.

Study on Performance Variation According to the Arrangements of Adjacent Vertical-Axis Turbines for Tidal Current Energy Conversion (인접한 조류발전용 수직축 터빈의 배치방식에 따른 성능 변화)

  • Lee, Jeong-Ki;Hyun, Beom-Soo
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.19 no.2
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    • pp.151-158
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    • 2016
  • Tidal farm is a multi-arrayed turbine system for utilizing tidal stream energy. For horizontal-axis turbine(HAT) system, it is recommended that each unit has to be deployed far apart in order to avoid hydrodynamic interference among turbines, as proposed by the European Marine Energy Centre(EMEC). But there is no rule for the arrangement of vertical-axis turbine(VAT) yet. Moreover it has been reported that a proper arrangement of adjacent turbines can enhance the overall efficiency even greater than an arrangement without mutual interference effect. This paper suggests the layout of VATs showing the better performances, which turned out to be quite different from HATs' arrangement. Numerical calculations were performed to investigate the performance variation in terms of the rotational direction as well as the distance between turbines. It has been shown that the best combination of rotational direction and distance between turbines can increase its performance higher about 9.2% than that of two independently operated turbines. It is likely that such improvement is due to the increased velocity between adjacent turbines. For diagonally arranged turbines, the maximum normalized mean power coefficient was obtained to be higher about 5.6% than that of two independent turbines. It is expected that the present results can be utilized for conceptual design of tidal farm to harness the tidal stream energy.

Effect of Genetic-Environmental Interaction on Quality of Wheat (소맥(小麥) 품질특성(品質特性)의 유전(遺傳) 및 환경적(環境的) 변이(變異))

  • Chang, Hak-Gil;Kim, Chang-Sik;Hah, Duk-Mo;Shin, Hyo-Sun
    • Korean Journal of Food Science and Technology
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    • v.18 no.1
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    • pp.31-37
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    • 1986
  • Seven cultivars of hard and soft wheat were evaluated by regression analysis for five bread quality characteristics to determine varietal response to environments. The regression coefficients were used as the measure of adaptability, and determination coefficients were used as the measure of stability by models of Eberhart and Russell. Phenotypic, genotypic and environmental correlation coefficient estimated for 6 characters tested in this experiments. Statistical analyses confirmed the strong influence of environment on five bread quality. A significant positive correlation exists between protein content, sedimentation value, pelshenke value and specific loaf volume. High heritability was found for sedimentation value ($h^2=0.747$), protein content ($h^2=0.557$) and specific loaf volume ($h^2=0.551$).

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Analysis of Assessment Types, Scoring Methods and Reliability of Science Performance Assessment in Middle and High School (중등학교 과학 수행평가의 평가 유형과 채점 방식 및 신뢰도 분석)

  • Lee, Ki-Young;An, Hui-Soo
    • Journal of The Korean Association For Science Education
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    • v.25 no.2
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    • pp.173-183
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    • 2005
  • In this study, we questioned what assessment types and scoring methods of science performance assessment(SPA) were being used in middle and high school, and how much these SPA scores were reliable(generalizable). To answer these questions, SPA data obtained from the seven schools were classified according to assessment type and scoring method. Based upon this classification, we analyzed the reliability by applying generalizability theory. The result, from the classification of assessment type and scoring method, showed that SPA types of the seven schools were divided into two types: paper-pencil type and task type. Paper-pencil type included answer(content)-restricted essay-type test solely. Task type has two parts: process and outcome assessment. As the results of analyzing scoring methods of the seven schools, there were two cases in the way of scoring methods: one case is scoring all essay-type items and performance tasks by one teacher, the other is scoring assigned performance tasks by two teachers. But the case of scoring assigned essay-type items or the case of cross scoring by two or more teachers were not found. The findings of the reliability analysis are as follows: (1) Effect of essay-type item to SPA score was larger than that of performance task. (2) There was remarkable difference among the seven schools' interaction effect of person and rater in scoring performance tasks. (3) Most of generalizability(reliability) coefficients of SPA for the seven schools were smaller than the acceptable generalizability coefficient(0.80). Therefore, the population of statistical parameters such as number of item, task and rater, should be increased for approaching the acceptable generalizability level.

A Study on the Interaction with Preservatives and UV-Filters, Packaging Materials for Sunscreen Preservation (자외선차단제품의 방부력 확보를 위한 방부제와 자외선 차단제, 제품 포장재의 상관성 연구)

  • Park, Tae-Hun;Kwack, Il-Young;Jeon, Gi-Boong;Kim, Hyun-Hee;Kim, Han-Kon;Shin, Kye-Ho
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.36 no.4
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    • pp.259-263
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    • 2010
  • We measured and compared the partition coefficients and absorption levels of preservative phenoxyethanol (PE), antimicrobial ethylhexylglycerin (EG) and UV-filters widely used in cosmetic products and more specifically evaluated the relative absorption level of PE depending on various packaging materials. The resulting partition coefficients of 11 UV filters in relation to PE and EG displayed EG with a relatively higher partition coefficients. The partition coefficients of Tinsorb M and Solaveil CT434 were also high. Among the UV-filter ingredients with EG absorption levels exceeding 40 % were Gransil PSQ, UV Titan M 160 and Micro $TiO_2$ MT 100 TV, whereas Gransil PSQ and Scadder showed PE absorption levels above 40 %. In addition, we confirmed that PE had displayed an absorption level of 7 ~ 8 % as a result of 1 month-long exposure to packaging material polyoxymethylene. This extensive research illustrates the possibility of producing the most potent preservative contents based on studying the relative compatibility between UV-filters and preservatives and selecting the adequate preservatives to be used. Furthermore, preservative level can also decline with passage of time depending on the type of packaging material used.

Development of a Maternal Identity Scale for Pregnant Women (임부의 모성 정체성 측정을 위한 척도개발)

  • 김혜원;홍경자
    • Journal of Korean Academy of Nursing
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    • v.26 no.3
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    • pp.531-543
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    • 1996
  • This study was done to develop a Maternal Identity Scale for Pregnant Women and to test the validity and reliability of the scale. A convenience sample of 161 pregnant women were asked to complete the MISP questionnaire which consisted of 45 item, this was done from December 20, 1995 to January 15, 1996. The research procedure were as follows. The first step was to identify a conceptual definition of maternal identity using Robin(1984)'s maternal identity and maternal experience during pregnancy. The second step was to operationalize the maternal identity, that is, perception of image possible of selves as mother, maternal role play by imagination, and the experiences of various emotional responses which are embedded in the mother-fetus dyad. The third step was item development which resulted in 45 items as appropriate measurement of maternal identity are except for the perception of image possible of selves as mother. The result findings were as follows : 1) Four factors for MISP (finally 40 items) were extracted through the principal component analysis and varimax rotation, and these contributed 49.3% of the variance in the total score. All 40 items in the scale loaded above .43 on one of 4 factors. 2) Each factor was named : factor 1 was named maternal role imagery and has 10 items, factor 2 was named happiness and has 11 items, factor 3 was named maternal fetal interaction and has 10 items, and the last factor 4 was named negative emotion and has 9 items. 3) Cronbach's -alpha coefficient for internal consistsncy was .92 for the total 40 items and .89, .90, .86, .78 for the four subscales in that order. Recommendations are suggested below : 1) The developed MISP be used to assess maternal readiness in pregnancy. 2) Replication study be done to test validity and relaibility. 3) For the overall measure of Maternal Identity in Pregnancy, scale for the perception of image possible of selves as mother, and cognitive domain be reorganized for the maternal identity in pregnancy. 4) It is necessary to identify variables that influences maternal pregnancy. 5) It Is necessary to identify that maternal identity in pregnancy is a reliable index of motherhood, to do correlation studies on maternal identity and major maternal variables in maternal transition period, to reoperationalize the maternal identity in postpartum, and finally to designate a longitudinal study of the maternal identity changes or stabilities.

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An analysis of horizontal deformation of a pile in soil using a continuum soil model for the prediction of the natural frequency of offshore wind turbines (해상풍력터빈의 고유진동수 예측을 위한 지반에 인입된 파일의 연속체 지반 모델 기반 수평 거동 해석)

  • Ryue, Jungsoo;Baik, Kyungmin;Lee, Jong-Hwa
    • The Journal of the Acoustical Society of Korea
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    • v.35 no.6
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    • pp.480-490
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    • 2016
  • As wind turbines become larger and lighter, they are likely to respond sensitively by dynamic loads applied on them. Since the responses at resonances are particularly interested, it is required to be able to predict natural frequencies of wind turbines reliably at early design stage. To achieve this, the foundation-soil analysis is needed to be carried out and a finite element approach is adopted in general. However, the finite element approach would not be appropriate in early design stage because it demands heavy efforts in pile-soil modelling and computing facilities. On the contrary, theoretical approaches adopting linear approximations for soils are relatively simple and easy to handle. Therefore, they would be a useful tool in predicting a pile-soil interaction, particularly in early design stage. In this study an analysis for a pile inserted in soil is performed. The pile and soil are modelled as a beam and continuum medium, respectively, within an elastic range. In this analysis, influence factors at the pile head for lateral loads are predicted by means of this continuum approach for various length-diameter ratios of the pile. The influence factors predicted are validated with those reported in literature, proposed from a finite element analysis.

Study on the Perceived Stress Level of Mothers in Neonatal Intensive Care Unit (NICU에 입원한 미숙아 어머니의 스트레스)

  • Kim, Tae-Im
    • Journal of Haehwa Medicine
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    • v.8 no.1
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    • pp.865-878
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    • 1999
  • With advances in neonatal medicine, smaller and sicker infants are surviving premature birth. As these tiny patients battle for their lives, their parents also struggle with psychological consequences of an unexpected role. The birth of a sick infants has long been documented as stressful events for the parents. High stress levels may alter parents' interaction with their baby and impair their communication with health professionals, which can in turn affect parents' participation in care planning and decision making. Nursing interventions aimed at reducing the parental stress and anxiety levels during this crisis may have a positive impact on their ability to form an attatchment to their baby and make prudent decisions about his care. The planning of such interventions would be inhanced if the contributions of various factors to increased parental stress levels were identified. This descriptive study was conducted to understand the contents and degree of parental stress in the NICU during their premature's hospitalization, and to give a baseline data in developing nursing intervention program. Subjects were the 60 mother of hospitalized newborn in NICU of 2 University Hospital in Taejon City from April 1st, 1999 to June 30th, 1999, who agreed to take part in this study. The instrument used in this study were Parental Stressor Scales:NICU(PSS:NICU) developed by Miles et al.. and validated by 3 NICU practitioners and 3 child health nursing faculties. The questionnaire has 4 dimensions and 45 items; sight and sounds of NICU(5 items), babies' appearance and behavior nursing intervention(19 items), parental role alteration and relationship with their baby(10 items), health team communication(11 items). The questionnaire asks parents to rate each item on a five-point Likert type scale that ranges from "not stressful" (1) to "extremely stressfu1"(5). Total scores representing overall stress from the NICU environment are calculated by summing response to each item. A high score indicates high stress. A subscale score is calculated by summing the responses to each item in the subscale. Cronbach's ${\alpha}$ coefficients were .93. The data was analyzed as average, Frequency, Standard deviation, t-test, ANOVA, Pearson correlation coefficient by use of SPSS/PC+. The results of this study is summarized as follows ; 1. The total perceived stress level score of mothers of premature baby was slightly high($3.66{\pm}1.1$). The highest scored dimension was 'relationship with their baby and parental role change'($4.21{\pm}0.9$), and next were 'appearance and behavior of the baby'($3.92{\pm}1.1$), 'communication with health team'($3.32{\pm}1.3$), 'sight and sounds of NICU'($3.30{\pm}1.1$). 2. There were statistically significant correlation noted ; mother's perceived severity of the baby's condition(F=8.0012, P= .0125) and baby's gestational age(r = -.4724, P = .0500). In summary, information about physical environment of NICU, the mother's perceived severity of premature baby's state, maternal role change related variables and the knowledge of characteristics of premature baby must be included in nursing intervention program of mother's of premature baby in reducing the parental stress and anxiety level. It is suggested that each NICU needs to develop a nurse managed supportive care program for parents of premature baby. Also, it is suggested that there need to investigate the coping mechanism of mother of premature baby.

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Varietal and Yearly Differences of Lignan Contents in Fruits of Collected Lines of Schizandra chinensis Baillon (오미자 수집종별 리그난 함량의 연차간 차이)

  • Kim, Kwan-Su;Park, Chun-Gun;Bang, Jin-Ki
    • Korean Journal of Medicinal Crop Science
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    • v.11 no.1
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    • pp.71-75
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    • 2003
  • To know the varietal difference and yearly changes of lignan contents in the fruits of collected lines of Schizandra chinensis Baillon, three lignan compounds, schizandrin, gomisin A, and gomisin N, were quantitatively analyzed using High Performance liquid Chromatography. The average contents of schizandrin, gomisin A, and gomisin N, showed 0.78%, 0.25%, and 0.63% in the 6-year-old fruits of 24 lines harvested in 1996, and 0.72%, 0.22%, and 0.63% in the 7-year-old ones of 59 lines harvested in 1997. There were the wide range of coefficient of variation (CV) values, the significant differences by the lines and harvest years, and the significant interaction between line and year for lignan contents. Schizandrin contents during 3 years, $1995{\sim}1997$, showed relatively higher amounts more than 0.9% in Chungju 143, Chungju 453, and Chungju 532. Among 23 lines analyzed from 1995 to 1997, Chungju 542, Chungju 547, and Chungju 580 contained continuously higher amounts more than 0.8% of schizandrin and had lower CV values of lignan contents by the harvest years than the other lines. There were a highly significant and negative correlation between fruit weight and lignan contents, and a positive correlation among contents of schizandrin, gomisin A, gomisin N, and total lignan.

Development and Evaluation of Separation Anxiety Scale for Mothers Using Child Care Facilities (보육시설 이용 어머니의 격리불안 측정 도구 개발 및 평가)

  • Cha, Hyo Sung;Ko, Jihyun;Lee, Kyoung Ju;Choi, Aelee;Lee, Gunjung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.1
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    • pp.409-420
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    • 2016
  • The aim of this study was to develop and validate an instrument to measure the separation anxiety of mothers who use child care facilities. The scale was developed as follows: initial items generated, validity and reliability tests performed, and final items extracted. The initial items were developed through a literature review and interviews. The content validity was verified by five experts. Using a final questionnaire, the data was collected from 204 mothers who used child care facilities with a convenient sampling method. The construct validity was evaluated by item analysis, exploratory factor analysis and confirmatory factor analysis. The results of confirmatory and exploratory factor analyses showed that the separation anxiety consisted of 6 factors: the mother's guilty feelings (5-items), safety of child care facilities (5-items), trust of teachers (5-items), child's anxiety (4-items), interaction anxiety with the child (4-items), and management of child care facilities (3-items). The separation anxiety scale for mothers using child care facilities consisted of 26 items. The reliability of the developed scale was examined. The Cronbach's ${\alpha}$ coefficient was 0.93. These results show that this scale is a valid and reliable instrument for measuring the separation anxiety level of mothers who use child care facilities.