• Title/Summary/Keyword: Covariance Structure Analysis

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A statistical analysis of the fat mass repeated measures data using mixed model (혼합모형을 이용한 체지방 반복측정자료에 대한 통계적 분석)

  • Jo, Jinnam;Chang, Un Jae
    • Journal of the Korean Data and Information Science Society
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    • v.24 no.2
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    • pp.303-310
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    • 2013
  • Forty two female students whose fat mass ratio was over 30% were participated in the experiment of fat mass loss of two treatments for 8 weeks. They kept diary for foods they ate every day, took a picture of the foods, transmitted the picture to the experimenter by the camera phone. Among those, 28 students took the picture by regular camera phone (Treatment A), and the other students used smart phone (Treatment B). Fat mass weight and its related variables had been measured repeatedly four times at an interval of two weeks during 8 weeks. It was shown from mixed model analysis of repeated measurements data that AR(1) covariance matrix was selected as the optimal covariance matrix pattern. The correlation between two successive times is highly correlated as 0.838. Based upon the AR(1) covariance matrix structure, the students using smart phones were somewhat more effective in losing fat mass weight than the students using regular camera phones. The time effect was highly significant, but the treatment-time interaction effect was insignificant. The baseline effect and total cholesterol were found to be significant, but the calories with taking foods were somewhat significant, but the waist to hip ratio was found to be insignificant.

Particle filter for model updating and reliability estimation of existing structures

  • Yoshida, Ikumasa;Akiyama, Mitsuyoshi
    • Smart Structures and Systems
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    • v.11 no.1
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    • pp.103-122
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    • 2013
  • It is essential to update the model with reflecting observation or inspection data for reliability estimation of existing structures. Authors proposed updated reliability analysis by using Particle Filter. We discuss how to apply the proposed method through numerical examples on reinforced concrete structures after verification of the method with hypothetical linear Gaussian problem. Reinforced concrete structures in a marine environment deteriorate with time due to chloride-induced corrosion of reinforcing bars. In the case of existing structures, it is essential to monitor the current condition such as chloride-induced corrosion and to reflect it to rational maintenance with consideration of the uncertainty. In this context, updated reliability estimation of a structure provides useful information for the rational decision. Accuracy estimation is also one of the important issues when Monte Carlo approach such as Particle Filter is adopted. Especially Particle Filter approach has a problem known as degeneracy. Effective sample size is introduced to predict the covariance of variance of limit state exceeding probabilities calculated by Particle Filter. Its validity is shown by the numerical experiments.

Determination of flutter derivatives by stochastic subspace identification technique

  • Qin, Xian-Rong;Gu, Ming
    • Wind and Structures
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    • v.7 no.3
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    • pp.173-186
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    • 2004
  • Flutter derivatives provide the basis of predicting the critical wind speed in flutter and buffeting analysis of long-span cable-supported bridges. In this paper, one popular stochastic system identification technique, covariance-driven Stochastic Subspace Identification(SSI in short), is firstly presented for estimation of the flutter derivatives of bridge decks from their random responses in turbulent flow. Secondly, wind tunnel tests of a streamlined thin plate model and a ${\Pi}$ type blunt bridge section model are conducted in turbulent flow and the flutter derivatives are determined by SSI. The flutter derivatives of the thin plate model identified by SSI are very comparable to those identified by the unifying least-square method and Theodorson's theoretical values. As to the ${\Pi}$ type section model, the effect of turbulence on aerodynamic damping seems to be somewhat notable, therefore perhaps the wind tunnel tests for flutter derivative estimation of those models with similar blunt sections should be conducted in turbulent flow.

A Resiliency Model for Families of Children with Disabilities (장애아동가족의 복원모델 연구)

  • Oh, Seung Ah;Lee, Yang Hee
    • Korean Journal of Child Studies
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    • v.22 no.2
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    • pp.113-132
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    • 2001
  • In order to develop a model for better understanding of causal relationships in resiliency factors in families of children with disabilities, 200 families participated in this adaptation of the Resiliency Model of McCubbin and McCubbin(1993). The 6 latent variables included in the hypothesized model were family stress, family hardiness, family schema, community support, family problem-solving communication, and family adaptation. The models were developed on the basis of confirmatory factor analysis and compared using covariance structure modeling (LISREL). Adequate fitness of the model was observed. Family stress showed negative effect on family schema and on family hardiness. Family schema showed positive effect on community support and on family hardiness. Family hardiness showed positive effect on family problem-solving communication, and family problem-solving communication showed positive effect on family adaptation.

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An Analysis of Single PPM Quality Innovation's Status using Covariance Structure Model (공분산구조모델에 의한 싱글 PPM 품질혁신 운동 추진현황 분석)

  • Koo, Il-Seob;Kim, Tae-Sung
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.28 no.4
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    • pp.102-108
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    • 2005
  • Single PPM Quality Innovation Movement is originally developed quality program in Korea for supplier's quality level-up since 1995. The quality target is below the 10ppm(parts per million) in outgoing quality and delivered goods plus field claim. Recently 1,053 companies is received Single PPM Quality Certification from government. This quality program is to realized the anticipated results not only duality level's increasing, but also company's confidence, competitiveness. We were able to obtain participations of 75 questionnaire, and derived statistics by means of SPSS/PC version 10.0. In this study, we find the bottleneck factor for promotion and upgrade S-PPM, and suggest a way out of difficulties.

A Study of Domestic Construction Quality Management Factor Analysis using Covariance Structure Model (공분산구조모델을 이용한 건설현장 품질경영 요인 분석)

  • Koo Il Seob;Kim Tae Sung;Lim Nam Gyu
    • Proceedings of the Safety Management and Science Conference
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    • 2005.05a
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    • pp.467-475
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    • 2005
  • This research has been conducted in order to assess the effects on quality management factor of the construction sites. 30 companies abiding by the 'construction industry law' and 32 companies abiding by the 'housing construction promotion law' have been researched in areas of quality-management environment, quality-management understanding, quality-management education on construction field, quality-system and quality-improvement. This construction quality factors are to realized the anticipated results not only quality level's increasing, but also company's confidence, competitiveness. We were able to obtain participations of 62 questionnaire, and derived statistics by means of SPSS/PC version 10.0. In this study, we find the bottleneck factor for promotion and upgrade quality management factor of the construction sites and suggest a way out of difficulties.

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A Study of Domestic Construction Quality Management Factor Analysis - (using Covariance Structure Model) (국내건설현장 품질경영 요인 분석에 관한 연구(공분산구조모델을 이용))

  • Kim Tae Sung;Koo Il Seob;Lim Nam Gyu
    • Journal of the Korea Safety Management & Science
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    • v.7 no.3
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    • pp.29-36
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    • 2005
  • This research has been conducted in order to assess the effects on quality management factor of the construction sites. 30 companies abiding by the 'construction industry law' and 32 companies abiding by the 'housing construction promotion law' have been researched in areas of quality-management environment, quality-management understanding, quality-management education on construction field, quality-system and quality-improvement. This construction quality factors are to realized the anticipated results not only quality level's increasing, but also company's confidence, competitiveness. We were able to obtain participations of 62 questionnaire, and derived statistics by means of SPSS/PC version 10.0. In this study, we find the bottleneck factor for promotion and upgrade quality management factor of the construction sites and suggest a way out of difficulties.

Causal Relationships in Children's Academic Achievement and Related Variables (아동의 학업성취 관련변인의 인과적 구조분석)

  • Lee, Kyeong Hwa;Jung, Hye Young
    • Korean Journal of Child Studies
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    • v.27 no.3
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    • pp.271-284
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    • 2006
  • In order to define their relative influence, this study analyzed causal relationships between academic achievement of elementary school students and such related variables as self-esteem and the psychological and economic environment of the home, including clarification of other significant variables affecting academic achievement. Participants were a sample of 485 5th grade students from 8 elementary schools in Busan. Correlation, analysis of covariance structure modeling, and model-fitness tests were applied to the data. Results indicated that the psychological environment of the home has the most significant influence on the academic achievement of children, and the economic environment of the home and self-esteem have relatively low or indirect influence.

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Structural Equation Model of Middle School Students' Stress, locus of control, and Adjustment (중학생의 스트레스 및 통제소재와 학교적응의 구조분석)

  • Lee, Kyeong-Hwa;Jung, Hye-Young
    • Journal of Fisheries and Marine Sciences Education
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    • v.19 no.1
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    • pp.8-18
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    • 2007
  • In order to define their relative influence, this study analyzed causal relationships between school adjustment of middle school students and such related variables as locus of control and stress, including clarification of other significant variables affecting school adjustment. Participants were a sample of 331 students from 3 middle schools in Busan. Correlation, analysis of covariance structure modeling, and model-fitness tests were applied to the data. Results indicated that stress on the school, home, social relationships, and self has the more significant influence on the school adjustment, and the locus of control has relatively low influence.

Families of Children with Disabilities: The Test of a Structural Model of Family Income, Hardiness, Pile-up Stress, Communication and Family Adaptation (장애아동 가족의 수입, 내구력, 누적 스트레스, 의사소통, 가족적응에 대한 구조모델검증)

  • 오승아
    • Journal of the Korean Home Economics Association
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    • v.40 no.9
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    • pp.175-189
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    • 2002
  • The purpose of this study was to test a structural model about family income as causally related to family hardiness, pile-up stress, communication, and family adaptation in families of children with disabilities. 250 families of children with disabilities participated as subjects. The models were developed on the basis of confirmatory factor analysis and compared using covariance structure modeling(LISREL). Adequate fitness of the model was observed. Family income showed negative effect on pile-up stress and positive effect on family adaptation. Pile-up stress showed negative effect on family hardiness. Family hardiness showed positive effect on family communication, and family communication showed positive effect on family adaptation.