• Korean Journal of Child Studies
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• v.33 no.3
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• pp.131-148
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• 2012

This study examines the scientific concept development of young children in terms of the day-night cycle. The subjects consisted of 180 three-, four-, and five-year-old children from two kindergartens and one children's center located in Seoul and Jeju. Individual interviews were conducted to collect verbal and pictorial responses on the day-night cycle. The scientific concepts on the day-night cycle are classified five stages including : no recognition, egocentric concept, initial mental models, synthetic mental models, and scientific mental models. Using two-way ANOVA, scores for the types of concept on the day-night cycles were then analyzed according to both the ages and genders of the children. The results reveal the existence of significant differences in terms of the types of concept of young children according to age. Most three-year-olds children had no recognition. Most three, four, and five-year-old children revealed egocentric concepts. Four-year-old children revealed that were in the initial stages of experiencing the mental models and synthetic mental models of the day-night cycle. Five-year-old children revealed that they were in the early stages of experiencing the initial, synthetic, scientific mental models of the day-night cycle. The results suggest appropriate ways of science education for young children based on the development of scientific concepts of the day-night cycle.

• Journal of the Ergonomics Society of Korea
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• v.22 no.1
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• pp.17-29
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• 2003

This study was initiated to develop a methodology for devising Korean virtual models for apparel shopping at internet shopping site. The data base for this study was the Korean National Anthropometric Survey in 1997. The subjects were 493 women and 626 men in 20's. The researchers also measured 88 males and females in age 20's to suggest back and front depth proportions which are not available from the survey. The virtual models' figure types were classified by the heights, drop value and bust(chest) girth. It was evaluated whether it is needed to separate figure type with bust(chest) girth. The body sizes of virtual models were suggested for side view model and front view model in 13cm height. Four female virtual models were suggested for front view and side view. Eight male virtual models were suggested for front view and side view. Each virtual model's height, breadth and depth proportions were calculated. Shoulder breadth. Bust(chest) breadth, waist breadth, hip breadth and proportions were calculated for front view model. The bust(chest) depth, waist depth, abdomen depth, hip depth and proportions were calculated for side view model. Height proportions were suggested for female and male virtual models.

• Computers and Concrete
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• v.5 no.4
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• pp.295-328
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• 2008

A previously published multiscale model for early-age cement-based materials [Pichler, et al.2007. "A multiscale micromechanics model for the autogenous-shrinkage deformation of early-age cement-based materials." Engineering Fracture Mechanics, 74, 34-58] is extended towards upscaling of viscoelastic properties. The obtained model links macroscopic behavior, i.e., creep compliance of concrete samples, to the composition of concrete at finer scales and the (supposedly) intrinsic material properties of distinct phases at these scales. Whereas finer-scale composition (and its history) is accessible through recently developed hydration models for the main clinker phases in ordinary Portland cement (OPC), viscous properties of the creep active constituent at finer scales, i.e., calcium-silicate-hydrates (CSH) are identified from macroscopic creep tests using the proposed multiscale model. The proposed multiscale model is assessed by different concrete creep tests reported in the open literature. Moreover, the model prediction is compared to a commonly used macroscopic creep model, the so-called B3 model.

• Korean Journal of Child Studies
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• v.26 no.6
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• pp.29-43
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• 2005

Emotional intelligence is a relatively new concept and little research to date has examined age differences. In order to examine developmental patterns in emotional intelligence(En, the Emotional Intelligence Test for Children(EITC, Lee, 2003) was administered to 367 children, 4- to 8-years of age. Data were analyzed by Multivariate Analysis of Variance(MANOVA) and post hoc univariate analyses of variables. Results showed significant differences by age in total and sub-total scores of EITC. When the means of test scores were presented graphically as developmental curves, EI totals and sub-scores showed the increases in EI that occurred with increased maturity. Additional research is needed to verify developmental models of EI and to explore which factors have an effect on EI.

• Journal of Families and Better Life
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• v.7 no.1
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• pp.119-138
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• 1989

This study attempts to apply its result to decision whether housewives are in the labor market or not by investigating the level of reservation wage of them and the influencing factors on it. The purpose of this study is to analyse the effects by identifying , on the basis of theoretical models, the factors that influence reservation wage, and to predict future state of female employment. 1) The level of reservation wage of housewives showed significant differences by husband's income, household asset, housewife's education level, housewife's age, number of children division of husband in household labor, and by three marketization of housework. 2) The variables which affected reservation wage of housewife independently had influence on it in the following order: Husband's income, education level, age affect positively reservation wage of housewife, and a negative relation has been found between division of husband, level of commodity substitution and reservation wage of housewife. 3) Husband's income, housewife's education level, housewife's age, division of husband in household labor, level of commodity substitution give direct effects on reservation wage of housewife. Education level, age, number of children and family type influenced reservation wage of housewife through level of commodity substitution indirectly.

• Journal of The Korean Astronomical Society
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• v.28 no.2
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• pp.119-137
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• 1995

The $UBVI_{KC}$ CCD photometry was performed in the central region(${\sim}20'{\times}20'$) of the extremely young open cluster IC1805. Member stars were selected in the (B-V)-(U-B) and (V-I)-(B-V) color-color planes. Applying recent stellar evolutionary models, we derived the age, age-spread, and initial mass function(IMF) of the cluster. IC1805 was found to be an extremely young($t_{age}{\sim}1.5Myr$) and has a flat IMF with the slope of ${\Gamma}=-1.0{\pm}0.2$.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.170-181
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• 2022

We live in a digital age. Smartphones are used by everyone from children to the elderly. And many smart devices are pouring out and changing our daily life a lot. However, even in the development of this digital age, there are some marginalized groups. There are also those who are reluctant to expose their information in the digital age. They have difficulty making reservations on their smartphones, using payment systems, logging into the site using various authentication and verification procedures, and entering and leaving buildings. We still carry most IDs, seals, certificates, etc. in physical form. Those who use smartphones are enjoying the convenience of the times. However, among the underprivileged, the desire to pass everything with only one device is growing. In this study, the most suitable smart band model was proposed by collecting the Delphi survey and the opinions of the general public. Future research is required to improve practical usability and utility by developing cheaper and more convenient models.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.3
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• pp.303-310
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• 2015

The study was conducted to analyze the genetic parameters of somatic cell score (SCS) of Holstein cows, which is an important indicator to udder health. Test-day records of somatic cell counts (SCC) of 305-day lactation design from first to fifth lactations were collected on Holsteins in Korea during 2000 to 2012. Records of animals within 18 to 42 months, 30 to 54 months, 42 to 66 months, 54 to 78 months, and 66 to 90 months of age at the first, second, third, fourth and fifth parities were analyzed, respectively. Somatic cell scores were calculated, and adjusted for lactation production stages by Wilmink's function. Lactation averages of SCS ($LSCS_1$ through $LSCS_5$) were derived by further adjustments of each test-day SCS for five age groups in particular lactations. Two datasets were prepared through restrictions on number of sires/herd and dams/herd, progenies/sire, and number of parities/cow to reduce data size and attain better relationships among animals. All LSCS traits were treated as individual trait and, analyzed through multiple-trait sire models and single trait animal models via VCE 6.0 software package. Herd-year was fitted as a random effect. Age at calving was regressed as a fixed covariate. The mean LSCS of five lactations were between 3.507 and 4.322 that corresponded to a SCC range between 71,000 and 125,000 cells/mL; with coefficient of variation from 28.2% to 29.9%. Heritability estimates from sire models were within the range of 0.10 to 0.16 for all LSCS. Heritability was the highest at lactation 2 from both datasets (0.14/0.16) and lowest at lactation 5 (0.11/0.10) using sire model. Heritabilities from single trait animal model analyses were slightly higher than sire models. Genetic correlations between LSCS traits were strong (0.62 to 0.99). Very strong associations (0.96 to 0.99) were present between successive records of later lactations. Phenotypic correlations were relatively weaker (<0.55). All correlations became weaker at distant lactations. The estimated breeding values (EBVs) of LSCS traits were somewhat similar over the years for a particular lactation, but increased with lactation number increment. The lowest EBV in first lactation indicated that selection for SCS (mastitis resistance) might be better with later lactation records. It is expected that results obtained from these multi-trait lactation model analyses, being the first large scale SCS data analysis in Korea, would create a good starting step for application of advanced statistical tools for future genomic studies focusing on selection for mastitis resistance in Holsteins of Korea.

• Computers and Concrete
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• v.34 no.3
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• pp.279-296
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• 2024

In this study, ensemble machine learning (ML) models are employed to estimate the hardened properties of Self-Compacting Geopolymer Concrete (SCGC). The input variables affecting model development include the content of the SCGC such as the binder material, the age of the specimen, and the ratio of alkaline solution. On the other hand, the output parameters examined includes compressive strength, flexural strength, and split tensile strength. The ensemble machine learning models are trained and validated using a database comprising 396 records compiled from 132 unique mix trials performed in the laboratory. Diverse machine learning techniques, notably K-nearest neighbours (KNN), Random Forest, and Extreme Gradient Boosting (XGBoost), have been employed to construct the models coupled with Bayesian optimisation (BO) for the purpose of hyperparameter tuning. Furthermore, the application of nested cross-validation has been employed in order to mitigate the risk of overfitting. The findings of this study reveal that the BO-XGBoost hybrid model confirms better predictive accuracy in comparison to other models. The R² values for compressive strength, flexural strength, and split tensile strength are 0.9974, 0.9978, and 0.9937, respectively. Additionally, the BO-XGBoost hybrid model exhibits the lowest RMSE values of 0.8712, 0.0773, and 0.0799 for compressive strength, flexural strength, and split tensile strength, respectively. Furthermore, a SHAP dependency analysis was conducted to ascertain the significance of each parameter. It is observed from this study that GGBS, Flyash, and the age of specimens exhibit a substantial level of influence when predicting the strengths of geopolymers.

• Journal of The Korean Astronomical Society
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• v.17 no.1
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• pp.1-14
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• 1984

Analyses of an integrated form $N(\tau)={\int}_{\tau}^{\infty}n(\tau)d{\tau}$ of the distribution of cluster ages, rather than its differential form $n(\tau)$, demonstrate that the observed distribution has clusters older than about 500 million years in a significant excess over theoretical model distributions. Considerations on cluster disruption processes show that a single disruption time-scale, frequently employed by current theoretical models, is no longer an adequate parameter for describing survival probability of clusters over wide age range, because different initial conditions of these clusters produce corresponding spreads in their lifetimes. To take into account for the spread in initial conditions, we have introduced an age-dependent disruption time, and deduced its age-dependence from the present-day age distribution of clusters. Results show a distinct two-stage variation: The newly introduced disruption time stays constant at about 50 million years for clusters younger than about 100 million years, while for clusters older than that it increases monotonically with the cluster age. This leads us to conclude that clusters experience different types of disrupting causes as they get old.