• Korean Journal of Child Studies
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• v.12 no.1
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• pp.78-90
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• 1991

This study investigated the relation between oral counting and numerical abilities of young children. The subjects were 33 four-year-old children and 47 five-year-old children from 2 preschools and 2 kindergartens in Kwangju. The test was individually administered in an empty classroom or a hallway by using counting buttons and number cards. The data were analyzed by t-test, Pearsons correlation and multiple regression analysis. The results indicated that (1) older children did better than younger children in oral counting. (2) but the older children did not do better than the younger children in the numerical abilities, (3) the numerical abilities of young children differed according to the degree of oral counting, and (4) the oral counting of young children was one significant predictor of numerical abilities. Findings support the inclusion of activities for oral counting in kindergartens.

• Journal of the Korean Home Economics Association
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• v.46 no.1
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• pp.117-129
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• 2008

In present study, using 1572 low-income families and 266 Head Start teachers from Family and Child Experiences Survey (FACES) in the U.S., we examined the effects of mothers' reading and the characteristics of interaction between teacher-child interaction on 4-and 5-year-olds' cognitive development represented by their verbal and numerical abilities. Frequencies of mothers' reading at home consistently predicted higher scores of children's Peabody Picture Vocabulary Test and Woodcock Johnson Applied Problems. Teachers' sensitivity and permissiveness in their interactions with children in classroom were positively related to children's verbal abilities and teachers' sensitivity predicted better numerical abilities of children after controlling for mothers' reading and the characteristics of family and teacher. The findings shed light on the contributions of teacher behaviors and familial factors to children's cognitive development calling for attention to the need for parent education on cognitively stimulating family environments and continuing education for early childhood teachers focusing on quality interactions with young children.

• The Korean Journal of Community Living Science
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• v.22 no.1
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• pp.145-154
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• 2011

This study investigated the effects of young children's learning-related skills and the maternal involvement on academic abilities. The sample consisted of 310 children from 7 child-care centers located in Seoul and Gyeonggi Province. All variables were measured by the teachers and the mothers of surveyed children. The instrument included the Korean Child Development Inventory(K-CDI) for 4 to 6-year olds and Preschool Learning Behavior Scale(McDermott et al 2000) and the questionnaire on mother's involvement about their children's education. The collected data was analyzed by t-test and hierarchical regression using the SPSS Program. The findings are as follows. First, regardless of the family income level, verbal comprehension and numerical abilities were positively associated with their learning-related skills of young children. Second, the interaction effect of learning-related skills and the mothers' involvement on verbal comprehension of young children in the low-income families was observed. However, no interaction effect was seen in terms of learning-related skills and the maternal involvement on verbal comprehension and numerical abilities of young children in the high-income families. These findings highlight the importance of learning-related skills and their mothers' involvement during the preschool period for the low-income family in improving the early academic achievement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.730-734
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• 2003

A beamforming method is a kind of spatial filter that focus the amy's signal capturing abilities in a desired direction. In this paper, we detect the location of a source under reflective condition using the multi-dimensional MUSIC algorithm then, we can iud the image source locations from the experimental geometry, and we reconstruct the partial fields for direct wave and reflected wave by using Adaptive nulling algorithm. Numerical simulations are performed to verify its performance under various conditions.

• Structural Engineering and Mechanics
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• v.76 no.1
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• pp.101-114
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• 2020

In this paper, an improved experience-based learning algorithm (EBL), termed as IEBL, is proposed to solve the nonlinear hysteretic parameter identification problem with Bouc-Wen model. A quasi-opposition-based learning mechanism and new updating equations are introduced to improve both the exploration and exploitation abilities of the algorithm. Numerical studies on a single-degree-of-freedom system without/with viscous damping are conducted to investigate the efficiency and robustness of the proposed algorithm. A laboratory test of seven lead-filled steel tube dampers is presented and their hysteretic parameters are also successfully identified with normalized mean square error values less than 2.97%. Both numerical and laboratory results confirm that, in comparison with EBL, CMFOA, SSA, and Jaya, the IEBL is superior in nonlinear hysteretic parameter identification in terms of convergence and accuracy even under measurement noise.

• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.89-94
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• 2011

In recent years there have been considerable attentions on nanoimprint lithography (NIL) by the display device and semiconductor industry due to its potential abilities that enable cost-effective and high-throughput nanofabrication. A major disadvantage of thermal NIL is the thermal cycle, that is, heating over glass transition temperature and then cooling below it, which requires a significant amount of processing time and limits the throughput. One of the methods to overcome this disadvantage is to improve the cooling performance in NIL process. In this paper, a numerical analysis model of cooling system in thermal NIL was development by CAD/CAE program and the performance of the cooling system was analyzed by the model. The calculated temperatures of nanoimprint device were verified by the measurements. By using the analysis model, the case that the cooling material is replaced by liquid nitrogen is investigated.

• Journal of Microbiology
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• v.34 no.2
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• pp.105-116
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• 1996

Of actinomycetes isolated from volcanic compost soils, 115 representative strains which showed distinctive morphologicla features were numerically classified, compared with reference strains of Streptomyces. One hundred and twenty unit characters were tested and the average probability of error was 4.27%. The cluster analysis resulted in two groups: group A included strains of actinomycetes except streptomycetes. Group A was divided into 2 major clusters (over 5 strains), 10-diaminopimelic acid. Group B was divided into 5 clusters, of which 4 clusters contained mesodiminopimelic acid and 1 cluster LL-diaminopimelic acid. The major clusters of group A showed higher abilities of substrate utilization and degradation, and higher resistance to inhibitors, whereas the minor and single member clusters of group A showed relatively higher antimicrobial activities. On the other hand, all clusters of group B showed relatively lower abilities of substrate utilization and degradation and lower resistance to inhibitors.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2500-2505
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• 2007

The vacuum interrupter (VI) is used for medium-voltage switching circuits due to its abilities and advantages as a compact and environmental friendly circuit breaker. In general, the application of a sufficiently strong axial magnetic field (AMF) permits the arc to be maintained in a diffused mode to a high-current vacuum arc. A full understanding of the vacuum arc physics is very important since it can aid to improve the performance of vacuum interrupter. In order to closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and hydrodynamic fields, simultaneously. In this study, we have investigated the electromagnetic behaviors of high-current vacuum arcs for two different types of AMF contacts, which are coil-type and cup-type, using a commercial finite element analysis (FEA) package, ANSYS. The present results are compared with those of MAXWELL 3D, a reliable electromagnetic analysis software, for verification.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.1
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• pp.7-12
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• 2008

The vacuum interrupter (VI) is used for medium-voltage switching circuits due to its abilities and advantages as a compacted environmental friendly circuit breaker. In general, the application of a sufficiently strong axial magnetic field (AMF) permits the arc to be maintained in a diffused mode to a high-current vacuum arc. A full understanding of the vacuum arc physics is very important since it can aid to improve the performance of vacuum interrupter. In order to closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and hydrodynamic fields, simultaneously. In this study, we have investigated the effect of changing geometrical parameters for electromagnetic behaviors of high-current vacuum arcs with two different types of AMP contacts, which are coil-type and cup-type, using a commercial finite element analysis (FEA) package, ANSYS. The present results are compared with those of MAXWELL 3D, a reliable electromagnetic analysis software, for verification.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2515-2518
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• 2008

The vacuum interrupter (VI) is widely used in medium-voltage switching circuits due to its abilities and advantages as an environmental friendly circuit breaker. An understanding of the vacuum arc flow phenomena is very important for improving the performance of vacuum interrupter. In order to closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and the thermal flow fields, simultaneously. In this study, we have investigated arc plasma constriction phenomena and an effect of AMF on the arc plasma with the high-current vacuum arcs for the cup-type AMF electrode by using a commercial finite element analysis (FEA) package, ANSYS. The simulation results applied with various AMFs and constant Joule heat generation show that strong axial magnetic field (AMF) permits the arc to be maintained in a diffused mode to a high-current vacuum arc. However, further studies are required on the two-way coupling method and radiation model for arc plasma in order to accomplish the advanced analysis method.