• 제목/요약/키워드: model factor

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Viscoelastic Stress Analysis of Polymeric Thin Layer Under Moisture Absorption (수분 흡수로 인해 고분자 박막에서 발생하는 점탄성 응력 해석)

  • 이상순;장영철
    • Journal of the Microelectronics and Packaging Society
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    • v.10 no.1
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    • pp.25-29
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    • 2003
  • This paper deals with the stress singularity induced at the interface corner between the elastic substrate and the viscoelastic thin film as the polymeric film absorbs moisture from the ambient environment. The boundary element method is employed to investigate the behavior of interface stresses. The order of the singularity is obtained numerically for a given viscoelastic model. It is shown that the stress singularity factor is relaxed with time, while the order of the singularity increases with time for the viscoelastic model considered.

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Validation of a Scale for Elementary School Students' Attitudes toward Mathematics (초등학생용 수학에 대한 태도척도의 개발과 타당화)

  • Jung, Hye Young;Lee, Kyeong Hwa
    • Korean Journal of Child Studies
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    • v.27 no.5
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    • pp.49-65
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    • 2006
  • This attitudes scale for prediction of mathematics achievement by elementary school students was developed from 50 initial items from the literature rated for content validity by 30 experts. The ratings rendered 31 revised items used for exploratory factor analysis and reliability tests. The 31 items were administered to 183 elementary students in 4th, 5th, and 6th grades, yielding 4 factors : enjoyment, confidence, value, and motivation with high inter-items consistency. To confirm appropriateness of the constructed model and to test its predictability in mathematics achievements, confirmative factor analysis and discriminant analysis were performed on 693 cases. Results showed that the attitude scale model of 4 factors can be recommended for use in the measurement of elementary school students' attitudes toward mathematics.

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Asymmetric Impact of IS Quality on User Satisfaction: Development of Resource Allocation Strategy of e-Government in Agriculture

  • Park, Heun Dong;Kim, Haneul
    • Agribusiness and Information Management
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    • v.5 no.1
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    • pp.42-54
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    • 2013
  • Information System (IS) Success Model proposed by DeLone and McLean is applied as a successful operation tool of information system, with its basic assumption of symmetric relationship between independent variables and dependent variables of the structural equation modeling. However, because previous studies have proved asymmetry of quality factors' influence structure on dependent variable by applying three-factor analysis, this study examined asymmetry of impact structure of quality factors introduced in IS Success Model on user satisfaction. Also the study applies structure equation modeling (SEM), three-factor analysis and importance and performance analysis (IPA) to develop resource allocation strategy for IS success. The study is able to provide IS practitioners with strategic implications for allocating and managing limited resources more effectively.

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A Study on Evaluation Model Construction of Man-Machine System Using Transfer Function (전달함수를 이용한 Man-Machine System의 평가 모델 구축에 관한 연구)

  • 김만균;함효준
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.19 no.40
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    • pp.291-299
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    • 1996
  • This study is concerned with the evaluation model construction of Man-Machine System(MMS) using Transfer Function in order to improve the control characteristics of an operator in the system and the procedure for ergonomic system design, When man, as a subsystem, performs his allocated functions in a system, many physical and physiological problems such as fatigue, stress and error occur. And the imperfect design of a MMS may itself be a situational factor that accelerates stress as well as an idiosyncratic factor that causes errors. So, the economy of design should be considered together with the ergonomic characteristics on the evaluation of MMS.

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Fracture Characteristics of Concrete at Early Ages (초기재령 콘크리트의 파괴특성)

  • Lee, Yun;Kim, Jin-Keun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.05a
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    • pp.215-220
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    • 2001
  • The objective of this study is to examine the fracture characteristics of concrete at early ages such as critical stress intensity factor, critical crack-tip opening displacement, fracture energy based on the concepts of the effective-elastic crack model and the cohesive crack model. A wedge splitting test for Mode I was performed on cubic wedge specimens with a notch at the edge. By varying strength and age, load-crack mouth opening displacement curves were obtained and the results were analyzed by linear elastic fracture mechanics. The results from the test and analysis showed that critical stress intensity factor and fracture energy increased, and critical crack-tip opening displacement decreased with concrete age from 1 day to 28 days. The obtained fracture parameters at early ages may be used as a fracture criterion and an input data for finite element analysis of concrete at early ages.

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Factors Affecting Emotional·Behavioral Problems in Early Adolescence: A Multilevel Model Study

  • Park, Hee Young;Choi, Yeon Hee
    • Research in Community and Public Health Nursing
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    • v.28 no.4
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    • pp.482-493
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    • 2017
  • Purpose: This study aims to investigate the individual and environmental factors related to emotional/behavioral problems to early adolescence in Korea by applying multilevel modeling. Methods: From the database of the 2014 Korean Child and Youth Panel Survey (KCYPS), the researchers selected 1,977 adolescents who are in the second year of middle school. Multilevel model analysis was performed to estimate the impact of relevant factors at the individual and environmental levels. Results: At the individual level, the significant factors associated with emotional/behavioral problems included BMI and study tendency in boys, and drinking, study tendency and economic levels in girls. At the environmental level, the significant factor associated with emotional/behavioral problems included relationship with the teacher. Conclusion: The emotional/behavioral problems of early adolescence are influenced not only by the individual factors but also by the environment factor. Therefore, the environment surrounding the adolescents should also be considered to prevent emotional/behavioral problems.

Analysis and Auto-tuning of Scale Factors of Fuzzy Logic Controller

  • Lee, Chul-Heui;Seo, Seon Hak
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 1998.06a
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    • pp.51-56
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    • 1998
  • In this paper, we analyze the effects of scaling factors on the performance of a fuzzy logic controller(FLC). The quantitative relation between input and output variables of FLC is obtained by using a qualsi-linear fuzzy model, and an approximate transfer function of FLC is dervied from the comparison of it with the conventional PID controller. Then we analyze in detail the effects of scaling factor using this approximate transfer function and root locus method. Also we suggest an on-line tuning method for scaling factors which employs an sample performance function and a variable reference for tuning index.

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Characteristics of Leakage and Rotordynamic Coefficients for Annular Seal with Multi-Land (이종 표면을 갖는 실의 특성해석)

  • Ha, Tae Woong
    • 유체기계공업학회:학술대회논문집
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    • 2002.12a
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    • pp.447-452
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    • 2002
  • An honeycomb/smooth land seal alternating with the honeycomb seal is suggested for structural enhancement in high pressure turbomachinery. Governing equations are derived for an honeycomb/smooth land annular gas seal based on Hirs' lubrication theory and Moody's friction factor model for smooth land and empirical friction factor model for honeycomb land. By using a perturbation analysis and a numerical integration method, the governing equations are solved to yield leakage and the corresponding dynamic coefficients developed by the seal. Theoretical results show that leakage is increasing and rotordynamic stability is decreasing as increasing the length of smooth land part in the honeycomb/smooth land seal.

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Characteristics of Leakage and Rotordynamic Coefficients for Annular Seal with Honeycomb/Smooth Land (Honeycomb/Smooth 표면을 갖는 비접촉 환상 실의 특성해석)

  • Ha, Tae-Woong
    • The KSFM Journal of Fluid Machinery
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    • v.5 no.4 s.17
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    • pp.40-46
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    • 2002
  • An honeycomb/smooth land seal alternating with the honeycomb seal is suggested for structural enhancement in high pressure turbomachinery. Governing equations are derived for an honeycomb/smooth land annular gas seal based on Hirs' lubrication theory and Moody's friction factor model for smooth land and empirical friction factor model for honeycomb land. By using a perturbation analysis and a numerical integration method, the governing equations are solved to yield leakage and the corresponding dynamic coefficients developed by the seal. Theoretical results show that the leakage increases and rotordynamic stability decreases as increasing the length of smooth land part in the honeycomb/smooth land seal.

Optimal Design of a Parallel-Flow Heat Exchanger by Using a Response Surface Method (반응표면법을 이용한 평행류 열교환기의 설계인자 최적화)

  • Oh, Seok-Jin;Lee, Kwan-Soo
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1028-1033
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    • 2004
  • The heat and flow characteristics in a single-phase parallel-flow heat exchanger was examined numerically to obtain its optimal shape. A response surface method was introduced to predict its performance approximately with respect to design parameters over design domain. Design parameters are inflow and outflow angle of the working fluid and horizontal and vertical location of inlet and outlet. The evaluation of the relative priority of the design parameters was performed to choose three important parameters in order to use a response surface method. A JF factor was used as an evaluation characteristic value to consider the heat transfer and the pressure drop simultaneously. The JF factor of the optimum model, compared to that of the base model, was increased by about 5.3%.

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