• Journal of the Korean Data and Information Science Society
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• 제25권4호
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• pp.941-949
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• 2014

Unit level logistic regression model with mixed effects has been used for estimating small area proportions, which treats the spatial effects as random effects and assumes linearity between the logistic link and the covariates. However, when the functional form of the relationship between the logistic link and the covariates is not linear, it may lead to biased estimators of the small area proportions. In this paper, we relax the linearity assumption and propose two types of kernel-based logistic regression models for estimating small area proportions. We also demonstrate the efficiency of our propose models using simulated data and real data.

• Communications for Statistical Applications and Methods
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• 제15권2호
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• pp.265-271
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• 2008

It is commonly believed that diseases of human or economic traits of livestock are caused not by single genes acting alone, but multiple genes interacting with one another. This issue is difficult due to the limitations of parametric-statistic methods of gene effects. So we introduce multifactor-dimensionality reduction(MDR) as a methods for reducing the dimensionality of multilocus information. The MDR method is nonparametric (i. e., no hypothesis about the value of a statistical parameter is made), model free (i. e., it assumes no particular inheritance model) and is directly applicable to case-control studies. Application of the MDR method revealed the best model with an interaction effect between the SNPs, SNP1 and SNP3, while only one main effect of SNP1 was statistically significant for LMA (p < 0.01) under a general linear mixed model.

• 지역사회간호학회지
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• 제33권3호
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• pp.290-298
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• 2022

Purpose: This study was conducted to determine factors influencing changes in the self-esteem of multicultural adolescents over time. Methods: A longitudinal design was adopted to analyze secondary data. This study used the 2nd, 4th, and 6th year data of Multicultural Adolescents Panel Study (MAPS) collected by the Korea Youth Policy Institute. The linear mixed model was utilized to analyze self-esteem changes over time. Results: The factors of sex and age of the students, the mother's Korean writing ability, and the Filipino or Japanese mothers had a significant effect on the self-esteem change of multi-cultural adolescents over time. Specifically, it was found that female students' self-esteem was decreased by 0.04 (t=-2.39, p=.017) more than male students over time. As the subject's age and mother's Korean writing ability increased, self-esteem was decreased by 0.01 (t=-2.53, p=.011) and 0.03 (t=-2.52, p=.012) over time. In addition, compared to that of those who had mothers from Korea, self-esteem of those who had Filipino or Japanese mothers was decreased by 0.04 significantly. Conclusion: Therefore, when developing a self-esteem promotion program, it is necessary to develop content by reflecting the characteristics of mothers as well as the gender and age of students. Furthermore, the significance of this study is in that it established a foundation for a positive self-identity of multicultural adolescents whose number is increasing recently by identifying factors affecting their self-esteem.

• 자원ㆍ환경경제연구
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• 제26권2호
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• pp.173-203
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• 2017

본 연구는 2000~2013년까지 14년간 서울, 부산, 대구, 인천 4개 대도시에 대한 총 주행거리, 도로연장길이, 대중교통 이용객수, 지역내총생산, 지역인구, 석유류 소비량에 대한 횡단시계열자료를 활용하여 도로연장에 대한 반등효과가 우리나라에도 적용되는지를 실증분석하였다. 혼합효과모형으로 추정한 결과 도로연장은 총 주행거리와 동반상승관계에 있는 반면, 대중교통 이용량은 총 주행거리와 역관계에 있는 것으로 나타났다. 이는 도로연장을 중심으로 하는 공급관리형 교통정책이 도시 광역화로 자가운전의 편의성을 직접적으로 증진시키거나, "걷기 힘든" 환경조성을 통해 자가운전 외 교통수단 이용의 편의성을 절감시킴으로써 추가적인 도로이용을 유인함을 뜻한다. 즉, 교통혼잡 및 정체 개선을 위해서는 현재의 도로연장 중심의 정책보다는 대중교통의 편의성 증진을 골자로 하는 교통수요관리 정책에 맞추어야 함을 시사한다.

• Journal of the Korean Data and Information Science Society
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• 제25권5호
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• pp.987-998
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• 2014

본 연구에서는 우리나라 환경부에서 최근에 구축한 아동 동집단 경시적 자료인 아동 건강과 환경 연구 (CHEER) 자료에 기초하여 주의력 결핍 과잉행동 장애 (ADHD)와 혈중 납 농도의 상관을 선형혼합모형을 사용하여 규명하고, CHEER 자료의 경시적 특성으로 나타나는 ADHD 점수의 "평균으로의 회귀" 현상을 보고하고자 한다. 또한 ADHD를 종점으로 한 혈중 납 농도의 용량-반응 곡선을 도출하며, 이렇게 도출된 용량-반응 곡선에 기초하여 몇 가지 상황 하에서 독성기준치인 벤치마크 용량 하한 (BMDL)을 유도한다.

• 응용통계연구
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• 제28권5호
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• pp.1035-1046
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• 2015

분산성분모형은 다양한 임의 요인들이 반응변수에 미치는 영향을 선형식의 형태로 나타내는 매우 유용하고 널리 사용되는 통계적 모형이다. 분산성분모형은 요인의 배치나 관측 자료의 구조에 따라 크게 교차배치와 지분배치로 나누어진다. 본 논문은 분산성분모형에서 요인의 배치구조와 분산성분의 크기에 따라 모형선택법의 경험적인 성질이 다르게 나타나는 현상을 체계적인 모의실험을 통하여 제시하고자 한다. 이원배치 분산성분모형에서 정보기준에 근거한 모형선택법, 즉 BIC 또는 AIC를 사용하는 경우 요인의 배치구조와 분산성분의 크기에 따라 모형선택법의 경험적인 성질이 다르게 나타나는 현상을 소규모 모의실험을 통하여 보여준다. 모의실험 결과에서 모형선택법의 경험적 성질이 요인의 배치 설계에 따라 다르게 나타난다는 사실을 확인하였으며 특히 요인의 배치구조가 지분 설계구조일때 내포된 요인의 분산성분의 상대적인 크기가 커짐에 따라 자료를 생성하는 모형보다 작은 모형을 선택하는 경향이 있다는 것이 모의실험으로 확인되었다.

• Structural Engineering and Mechanics
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• 제24권2호
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• pp.227-245
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• 2006

The performance of a three dimensional non-linear finite element model for hyperelastic material considering the effect of compressibility is studied by analyzing rubber blocks under different modes of deformation. It includes simple tension, pure shear, simple shear, pure bending and a mixed mode combining compression, shear and bending. The compressibility of the hyperelastic material is represented in the strain energy function. The nonlinear formulation is based on updated Lagrangian (UL) technique. The displacement model is implemented with a twenty node brick element having u, ${\nu}$ and w as the degrees of freedom at each node. The results obtained by the present numerical model are compared with the analytical solutions available for the basic modes of deformation where the agreement between the results is found to be satisfactory. In this context some new results are generated for future references since the number of available results on the present problem is not sufficient enough.

• Asian-Australasian Journal of Animal Sciences
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• 제19권4호
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• pp.468-474
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• 2006

Real time ultrasound data was generated on 10,596 live Hanwoo cows to study genetic variation on ultrasonic beef quality traits and to assess the best model to estimate genetic parameters on these traits. Pedigree stacking and data validation was done using the SAS statistical software and the genetic parameter estimates were obtained by EM-REML algorithm. Out of the five different multi-trait mixed animal models constructed, the optimal model included fixed effects of herd, year-season-appraisal, body condition score, linear and quadratic covariates for chest girth, the linear covariate effect of age and the random animal and residual effect of the five models studied. The heritability of longissimus muscle area (LMA), $12^{th}$ rib measurement of back fat thickness (BF) and marbling score (MS) was 0.11, 0.17 and 0.15, respectively. Genetic correlation of LMA vs. BF, LMA vs. MS and BF vs. MS was -0.15, 0.06 and 0.61, respectively. The results showed presence of genetic variation in these ultrasonic beef quality traits in Hanwoo cows and suggest that the selection of Hanwoo cows may be possible by performing ultrasonic scans on live animals, which will ultimately be helpful in reducing the generation interval and the cost of selection procedure.

• 보건행정학회지
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• 제33권3호
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• pp.295-310
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• 2023

Background: The long-term care (LTC) group has higher rates of chronic disease and disability registration compared to the general older people population. There is a need to provide integrated medical services and care for LTC group. Consequently, this study aimed to identify medical usage patterns based on the ratings of LTC and the characteristics of benefits usage in the LTC group. Methods: This study employed the National Health Insurance Service Database to analyze the effects of demographic and LTC-related characteristics on medical usage from 2015 to 2019 using a repeated measures analysis. A longitudinal logit model was applied to binary data, while a linear mixed model was utilized for continuous data. Results: In the case of LTC ratings, a positive correlation was observed with overall medical usage. In terms of LTC benefit usage characteristics, a higher overall level of medical usage was found in the group using home care benefits. Detailed analysis by medical institution classification revealed a maintained correlation between care ratings and the volume of medical usage. However, medical usage by classification varied based on the characteristics of LTC benefit usage. Conclusion: This study identified a complex interaction between LTC characteristics and medical usage. Predicting the requisite medical services based on the LTC rating presented a challenge. Consequently, it becomes essential for the LTC group to continuously monitor medical and care needs, even after admission into the LTC system. To facilitate this, it is crucial to devise an LTC rating system that accurately reflects medical needs and to broaden the implementation of integrated medical-care policies.

• 설비공학논문집
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• 제9권1호
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• pp.43-54
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• 1997

This paper presents an approximate analytical solution to a two-region one-dimensional model for the charging process of stratified thermal storage tanks with variable inlet temperature in the presence of momentum-induced mixing. Based on the superposition principle, an arbitrary-varying inlet temperature is decomposed into inherent discontinuous steps and continuous intervals approximated as a finite number of piecewise linear functions. This approximation allows the temperature of the upper perfectly-mixed layer to be expressed in terms of constant, linear and exponential functions with respect to time. Applying the Laplace transform technique to the model equation for the lower thermocline layer subject to each of three representative interfacial conditions yields compact-form solutions, a linear combination of which constitutes the final temperature profile. A systematic method for deriving solutions to the plug-flow problem having polynomial-type boundary conditions is also established. The effect of adiabatic exit boundary on solution behaviors proves to be negligible under the actual working conditions, which justifies the assumption of semi-infinite domain introduced in the solution procedure. Finally, the approximate solution is validated by comparing it with an exact solution obtained for a specific variation of inlet temperature. Excellent agreements between them suffice to show the necessity and utility of this work.