• Journal of Science Education
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• v.34 no.1
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• pp.1-11
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• 2010

This study analyzes the factors influencing academic achievement on mathematic and scientific subject and its change in Korean youth by using a sample from KYPS(Korea Youth Panel Survey) data. The results are as follows: First, academic achievement on mathematic and scientific subject of Korean youth shows quadratic curve that their interrelationship between intercept and slope of academic achievement are negative which is statistically significant. Second, analysis of Latent Growth Models shows that parents, teacher, peer group, self esteem, income of family, high school tracks are found to be a statistically significant factor on mathematic. And scientific subject is affected by parents, teacher, peer group, self esteem, income of family, high school tracks. Also, Interesting finding is that father's job is not significant to dependent variables. These findings show that academic achievement on mathematic and scientific subject of the Korean youth are the quadratic curve and influenced by parents, teacher, peer group, self esteem, income of family, high school tracks. To improve youth's mathematic and scientific, Korea educational fields and educators should have policy to care youth's relationship with parents, teachers and self esteem.

• Clean Technology
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• v.27 no.3
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• pp.223-231
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• 2021

In order to address many issues associated with large volume changes of silicon, which has very low electrical conductivity but offers about 10 times higher theoretical capacity than graphite (Gr), a silicon nanoparticles/hollow carbon (SiNP/HC) composite having bimodal-mesopores was prepared using silica nanoparticles as a template. A control SiNP/C composite without a hollow structure was also prepared for comparison. The physico-chemical and electrochemical properties of SiNP/HC were analyzed by X-ray diffractometry, X-ray photoelectron spectroscopy, nitrogen adsorption/desorption measurements for surface area and pore size distribution, scanning electron microscopy, transmission electron microscopy, galvanostatic cycling, and cyclic voltammetry tests to compare them with those of the SiNP/C composite. The SiNP/HC composite showed significantly better cycle life and efficiency than the SiNP/C, with minimal increase in electrode thickness after long cycles. A hybrid composite, SiNP/HC@Gr, prepared by physical mixing of the SiNP/HC and Gr at a 50:50 weight ratio, exhibited even better cycle life and efficiency than the SiNP/HC at low capacity. Thus, silicon/carbon composites designed to have hollow spaces capable of accommodating volume expansion were found to be highly effective for long cycle life of silicon-based composites. However, further study is required to improve the low initial coulombic efficiency of SiNP/HC and SiNP/HC@Gr, which is possibly because of their high surface area causing excessive electrolyte decomposition for the formation of solid-electrolyte-interface layers.

• Journal of Digital Convergence
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• v.17 no.3
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• pp.323-330
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• 2019

The purpose of this study was to investigate the effect of body mass index(BMI) and waist circumference(WC) on hemoglobin(Hb) in Korean Adult. This study analyzed the data of 2015, The Sixth KNHANES. Data were analyzed using descriptive statistics, t-test, ANOVA and Scheffe's test, Pearson correlation coefficient and multivariate logistic regression analysis(SPSS 25.0). The major findings, The subject's Hb In BMI, obese was the highest(F=97.862, p<0.001). The Hb In WC, $WC{\geq}90cm$ was higher for male(t=4.909, p<0.001), and $WC{\geq}85cm$ was higher for female(t=5.088, p<0.001). Hb has a significant positive correlated with BMI(r=0.188, p<0.001), WC(r=0.298, p<0.001). In male, Hyperhemoglobinemia was 2.30 times(p<0.001) higher in obese and 1.81 times(p<0.001) higher in $WC{\geq}90cm$. In female, Hyperhemoglobinemia was 1.99 times(p=0.002) higher in overweight, 5.66 times(p<0.001) higher in obese, and 4.27 times(p<0.001) higher in $WC{\geq}85cm$. In conclusion, adult obesity prevention and management programs should include exercises, diets, and education, and exercise interventions specifically for eliminating abdominal obesity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.173-181
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• 2021

Reinforced concrete structures are exposed to various environments, resulting in reinforcement corrosion due to moisture and ions penetration. Reinforced concrete corrosion causes a decrease in the durability performance of reinforced concrete structures. One solution to mitigate such issues is using FRP rebars, which offer several advantages such as high tensile strength, corrosion resistance, and light-weight than conventional rebars, in reinforced concrete instead of conventional steel rebars. The FRP rebar used should be examined at the limit state because FRP reinforced concrete has linear behavior until its fracture and can generate excessive deflection due to the low elastic modulus. It should be considered while designing FRP reinforced concrete for flexure. In the ultimate limit state, the flexural strength of FRP reinforced concrete as per ACI 440.1R is significantly lower than the flexural strength by applying both the environmental reduction and strength reduction factors accounting for the material uncertainty of FRP rebar. Therefore, in this study, the experimental results were compared with the deflection of the proposed effective moment of inertia referring to the local and international standards. The experimental results of GFRP and BFRP reinforced concrete were compared with the flexural strength as determined by ACI 440.1R and Fib bulletin 40. The flexural strength obtained by the experimental results was more similar to that obtained by Fib bulletin 40 than ACI 440.1R. The flexural strength of ACI 440.1R was conservatively evaluated in the tension-controlled section.

• Journal of Educational Research in Mathematics
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• v.19 no.3
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• pp.461-477
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• 2009

In this study, an operational analysis in the context of linear equations is presented. For the analysis, several second-order models concerning students' whole number knowledge and fraction knowledge based on teaching experiment methodology were employed, in addition to our first-order analysis. This ontogenetic analysis begins with students' Explicitly Nested number Sequence (ENS) and proceeds on through various forms of linear equations. This study shows that even in the same representational forms of linear equations, the mathematical knowledge necessary for solving those equations might be different based on the type of coefficients and constants the equation consists of. Therefore, the pedagogical implications are that teachers should be able to differentiate between different types of linear equation problems and propose them appropriately to students by matching the required mathematical knowledge to the students' potential constructs.

• Korean Journal of Plant Resources
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• v.13 no.1
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• pp.80-88
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• 2000

External morphology and numerical taxonomy by principal component analysis and cluster analysis were investigated to understand the taxonomic relationships on the populations of Hanabusaya asiatica from 6 different habitats. Additionally H. latisepala was used as a outgroup. The distinct characters to each habitat were not present in the measurement of 21 qualitative characters except for some native individuals in the top of Mt. Sorak and Hyangrobong based on leaf shape and bracts. This results were recognized as the continuous variations of external morphology. The populations of H. latisepala and H. asiatica were identified by calyx lobe shape. The results obtained based on the principal component(PC) analysis of treated 78 OTU were divided into two groups by PC 1,2,3, and the sums of contributions for the total variance were 50.07% (PC1 22.3% , PC2 15.7%, PC3 12.0%, respectively), and six populations were not distinctly identified as illustrated in two dimensions with PC1 and PC2. In cluster analysis based on average linkage cluster analysis and Ward's method, there were similarities in the composition of clustered taxa, and each populations were not identified.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.10
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• pp.1815-1821
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• 2006

In this paper, the subthreshold swing has been analyzed for FinFET under channel length of 20nm. The analytical current model has been developed , including thermionic current and tunneling current models. The potential distribution by Poisson equation and carrier distribution by Maxwell-Boltzman statistics are used to calculate thermionic emission current and WKB(Wentzel-Kramers-Brillouin) approximation to tunneling current. The cutoff current is obtained by simple adding two currents since two current is independent. The subthreshold swings by this model are compared with those by two dimensional simulation and two values agree well. Since the tunneling current increases especially under channel length of 10nm, the characteristics of subthreshold swing is degraded. The channel and gate oxide thickness have to be fabricated as am as possible to decrease this short channel effects, and this process has to be developed. The subthreshold swings as a function of channel doping concentrations are obtained. Note that subthreshold swings are resultly constant at low doping concentration.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.608-611
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• 2011

Laser-induced combustions and explosions generated by high laser irradiances were explored by Laser-Induced Breakdown Spectroscopy (LIBS) in rich, and stoichiometric conditions. The laser used for target ablation is a Q-switched Nd:YAG laser with 7 ns pulse duration at wavelength of 1064 nm laser energies from 40 mJ to 2500 mJ ($6.88{\times}10^{10}-6.53{\times}10^{11}\;W/cm^2$). The plasma light source from aluminum detected by the echelle grating spectrometer and coupled to the gated ICCD(a resolution (${\lambda}/{\Delta}{\lambda}$) of 5000). This spectroscopic study has been investigated for obtaining both the atomic signals of aluminum (fuel) - oxygen (oxidizer) and the calculated ambient condition (plasma temperature and electron density). The essence of the paper is observing specific electron density ratio which can support the processes of combustion and explosion between ablated aluminum plume and oxygen from air by inducing high power laser.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.66-74
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• 2017

This study was aimed to construct a theoretical model for managing persons with early psychosis. We systematically searched SCOPUS, PubMed, RISS, Web of Knowledge, and KoreaMed for related factors to manage persons with early psychosis. Significant terms or phrases for a preliminary structural model were obtained from 19 studies since 2000 regarding the management of persons with early psychosis. Moreover, the content validity for the model was evaluated by 22 professionals. The study results revealed 51 factors for managing persons with early psychosis extracted by meta-analysis, and all factors were divided into 21 medium classification and 8 categories. A theoretical model was constructed with 8 categories, by using the middle range theory of Peplau's Interpersonal Relationships in Nursing. The results suggest that the theoretical model for the management of persons with early psychosis provides a sound theoretical basis for future study.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.399-410
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• 2015

The primary goal of the study is to examine the possibility of applying the time series model to forecasting demand and supply of social services. In the study, we used survey data based on a nationally represented sample which is secondary processed data. We selected developmental rehabilitation service. The analysis, we made models of a demand and a supply using time series analysis. Utilizing the estimates, we identified each model's pattern. This study provides an empirical evidence to suggest benefits of using the time series model for forecasting the demand and the supply pattern of newly introduced social services. We also provide discussions on policy implications of utilizing demand and supply time series models in the process of developing new social services.