• 대한가정학회지
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• 제33권4호
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• pp.173-188
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• 1995

This study examined the characteristics of the relationship of HOME, sociodemographic variables and children's verbal ability at age four, five, six, Expecially this study investigated causal relationships amoong the variables which are supposed to affect children's verbal ability by children's age and sex. The subject of this study were 180 children and their mothers. Instruments included inventory of home stimulation(HOME), inventory of socio-demographic variables, inventory of the children's verbla ability. The results obtained from this study were as follows : 1. For the most part, HOME and socio-demographic variables had a significant positive correlation with children's verbal ability. 2. The variables that significantly predicted children's verbal ability differed according to children's age and sex. That is, play materials, breadth of experience and economic status of the home were predictive of boy's verbal ability at age four, while aspects of physical environment, breadth of experience were predictive at age five, fostering maturity and independence, parent's education were predictive at age six. And developmental stimulation and breadth of experience were predictive of girl's verbal ability at age four, while developmental stimulation, economic status of the home were predictive at age five, developmental stimulation and play materials were predictive at age six. 3. the results of the analysis of the causal model showed that the kind of variables that affected children's verbal ability directly differed according to children's age and sex. That is, indirect stimulation and direct stimulation affected boy's verbal ability directly at age four and five, while indirect stimulation and parent's education affected boy's verbal ability at age six. And indirect stimulation, direct stimulation, emotional climate of the home affected girl's verbal ability directly at age four, while direct stimulation, economic status of the home, indirect stimulation affected directly at age five, parent's education, indirect stimulation and direct stimulation affected girl's verbal ability at age six. 4. Another causal model of the HOME, socio-demographic variables affecting children's verbal ability showed that total HOME scores more significantly affected boys and girl's verbal ability directly than socio-demographic variables at all ages.

• Journal of Radiation Protection and Research
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• 제46권4호
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• pp.170-177
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• 2021

Background: The International Commission on Radiological Protection is preparing to provide reference dose coefficients for environmental radioiodine intake based on newly developed age-specific biokinetic models. However, the biokinetics of iodine has been reported to be strongly dependent on the dietary intake of stable iodine; for example, the thyroidal uptake of iodine may be substantially lower in iodine-rich regions than in iodine-deficient regions. Therefore, this study attempted to establish a system of age-specific thyroid dose estimation for South Koreans, whose daily iodine intakes are significantly higher than that of the world population. Materials and Methods: Korean age-specific biokinetic parameters and thyroid masses were derived based on the previously developed Korean adult model and the Korean anatomical reference data for adults, respectively. This study complied with the principles used in the development of age-specific biokinetic models for world population and used the ratios of baseline values for each age group relative to the value for adults to derive age-specific values. Results and Discussion: Biokinetic model predictions based on the Korean age-specific parameters showed significant differences in iodine behaviors in the body compared to those predicted using the model for the world population. In particular, the Korean age-specific thyroid dose coefficients for ¹²⁹I and ¹³¹I were considerably lower than those calculated for the world population (25%-76% of the values for the world population). Conclusion: These differences stress the need for Korean-specific internal dose assessments for infants and children, which can be achieved by using the data calculated in this study.

• 농촌계획
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• 제11권3호
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• pp.59-67
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• 2005

According to diverse studies in population migration, there has been a strong age-dependent population distribution in Korea. It is shown that a particular age-group tends to reside in a particular locale or community and the effect possesses usually statistical significance. We quantitatively address this issue: how certain division of age group resides in different region of the country, and investigate possible cause of this migration pattern for different age groups. In this study, population migration trend at age groups of 20s, 30s, 40s and 50s has been analyzed incorporating a spatial econometrics model that accounts for diverse statistical pitfalls such as spatial autocorrelation and spatial dependency. We found that migration trend for different age group corresponds to regional characteristics differently. The study concludes with some policy implications and suggests a need of further study.

• 산업공학
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• 제19권4호
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• pp.316-323
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• 2006

In this study, based on Weibull proportional age reduction model and age replacement policy, we analyze economic life of cutting tool which allows re-grinding. Re-grinding task, usually for high-priced machining tools(e.g., broaching tool), is a kind of preventive maintenance activities to extend tool life at the completion of a lot production. The numerical results are also presented. Among the parameters of Weibull proportional age reduction model, the re-grinding effect parameter and Weibull shape parameter have a strong effect on economic tool life, and in the cost parameters, shortage cost is most sensitive. With further study on the parameter estimation of tool life process and cost function, this study can be expected to give more practical contribution to management of general machining tools.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.397-402
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• 2001

Microstructural characteristics such as hydrates and porosity greatly influence the development of concrete strength. In this study, a strength estimation model for early-age concrete considerig, the microstructural characteristics was proposed, which considers the effects of both an increment of degree of hydration and capillary porosity on a strength increment. Hydration modeling and compressive strength test with curing temperature and curing ages were carried out. By comparing test results with estimated strength, it is found that the strength estimation model can estimate compressive strength of early-age concrete with curing ages and curing temperature within a margin of error.

• Journal of applied mathematics & informatics
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• 제30권1_2호
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• pp.183-200
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• 2012

A two-strain epidemic model with an age structure mutation and varying population is studied. By means of the spectrum theory of bounded linear operator in functional analysis, the reproductive numbers according to the strains, which associates with the growth rate ${\lambda}^*$ of total population size are obtained. The asymptotic stability of the steady states are obtained under some sufficient conditions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권7호
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• pp.2480-2495
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• 2014

This paper describes a hierarchical method for image-based age estimation that combines age group classification and age value estimation. The proposed method uses a coarse-to-fine strategy with different appearance features to describe facial shape and texture. Considering the damage to continuity between neighboring groups caused by fixed divisions during age group classification, a dynamic grouping technique is employed to allow non-fixed groups. Based on the given group, an ordinal hyperplane ranking (OHRank) model is employed to transform age estimation into a series of binary enquiry problems that can take advantage of the intrinsic correlation and ordinal information of age. A set of experiments on FG-NET are presented and the results demonstrate the validity of our solution.

• 한국조리학회지
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• 제12권2호
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• pp.137-150
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• 2006

The aim of this study was to determine the relative importance of a set of attributes which influence purchase decision of leaf mustard kimchi such as color, package, taste, availability and price, and to identify tourist product factor combinations which confer the highest utility to tourists of each age group. Conjoint model was used for this study. The findings from this study were as follows. First, it was found that all age groups regarded taste and price as the very important factor. Second, it was found that the products with different attribute levels were preferred by age groups. Third, it was found that the most preferred product in each age group was significantly different by cluster. Finally, it was found that the most preferred simulation product was different by age groups.

• 한국생활과학회지
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• 제16권5호
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• pp.1031-1040
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• 2007

The purpose of this study was to assess the causal relationships of attitude toward fish eating, health involvement, convenience, fish consumption and age. A total of 235 questionnaires were completed. Structural equation model was used to assess the causal relationships among constructs. Results of the study demonstrated that the structural equation analysis result for the data also indicated excellent model fit. The influences of age on health involvement and convenience were statistically significant. The influences of health involvement on attitude toward fish eating and fish consumption behavior were statistically significant. The influence of convenience on fish consumption behavior were statistically significant. Moreover, the age had a significant indirect effect on attitude toward fish eating through health involvement. The age also had a significant indirect effect on fish consumption behavior through convenience.

• 콘크리트학회논문집
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• 제12권2호
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• pp.31-42
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• 2000

This paper discusses the validity of models predicting the compressive strength of concrete subjected to various temperature histories and the shortcomings of existing rate constant model and apparent activation energy concept. Based on the discussion, a modified rate constant model is proposed. The modified rate constant model, in which apparent activation energy is a nonlinear function of curing temperature and age, accurately estimates the development of the experimental compressive strengths by a few researchers. Also, the apparent activation energy of concrete cured with high temperature decreases rapidly with age, but that of concrete cured with low temperature decreases gradually with age. Finally generalized models to predict apparent activation energy and compressive strength are proposed, which are based on the regression results.