• 한국초등과학교육학회지:초등과학교육
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• 제27권4호
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• pp.446-454
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• 2008

The purpose of this study was to examined the effects of different grouping according to the levels of students' achievement in science cooperative learning on students' science academic achievements, science-related attitudes, perceptions of science learning environment and self-efficacies. The results of this study can be summarized as following. First, the homogeneous grouping was more effective than the heterogeneous grouping in improving the science academic achievements of high academic ability students. Second, the homogeneous grouping was more effective than the heterogeneous grouping in improving the science-related attitude of students, especially for low academic ability students. Third, both the homogeneous grouping and the heterogeneous grouping improved the perceptions of science learning environment of students. For low academic ability students, the homogeneous grouping was more effective. Fourth, the homogeneous grouping was more effective than the heterogeneous grouping in improving self-efficacies of students, especially for middle and low academic ability students.

• 영어어문교육
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• 제12권4호
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• pp.185-210
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• 2006

This study has two purposes. First, it aims to suggest an appropriate approach to English writing education for Korean high school students in a cooperative learning situation. It also aims to suggest what type of learner grouping, either homogeneous or heterogeneous, is appropriate by comparing the learners' writing abilities and the changes of their affective factors after being exposed to cooperative EFL writing instruction. Two homogeneous classes were selected and instructed to write in English for 11 weeks. One was composed of homogeneous small groups based on the students' writing scores, and the other was composed of heterogeneous small groups, again based on the students' writing scores. The results showed that the improvement between the two class types was quite different across different proficiency levels. For example, although there is little difference between the homogeneous and the heterogeneous classes of low and intermediate-level learners in writing ability improvement, high-level students showed a significant difference between the classes. In addition, it was found that class participation correlated significantly to writing ability improvement. Cooperative learning was proved to be an effective writing instructional approach to encourage learners' interest and increase their self-confidence; however, the results did not show any significant differences in learners' affective domain between the homogeneous and the heterogeneous classes. Similarly, the learners' grouping preference was not affected by the grouping method.

• 설비공학논문집
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• 제28권4호
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• pp.153-157
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• 2016

In case of metal insulation, which is produced by stacking stainless steel sheets and air layers in a multi-stack manner at a specific thickness, insulation performance will be evaluated based on thermal transmittance rather than the intrinsic physical properties of each material such as thermal conductivity. However, there is no standard for measuring thermal transmittance targeted for non-homogeneous insulation which is used in relatively high temperature conditions such as a power station. In this study, the thermal conductivity of homogeneous insulation acquired by the standardized guard hot plate method and the thermal conductivity of homogeneous insulation measured by the newly developed performance tester were compared to verify the confidence level of the tester. As a result, thermal conductivity acquired by the newly developed thermal transmittance tester was about 6% higher than the thermal conductivity measured by the existing guard hot plate method under the anticipated service temperature conditions.

• 한국주조공학회지
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• 제33권3호
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• pp.122-126
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• 2013

Recently, heat-resistant aluminum alloy has been re-focused as a downsizing materials for the internal combustion engines. Heat-resistant Al alloy development and many researches are still ongoing for the purpose of improving thermal stability, high-temperature mechanical strength and fatigue properties. The conventional principle of heat-resistant Al alloy is the precipitation of intermetallic compounds by adding a variety of elements is generally used to improve the mechanical properties of Al alloys. Heat resistant aluminum alloys have been produced by CrW homogeneous solid solution to overcome the limit of conventional heat resistant aluminum alloy. From EPMA, it is found that CrW homogeneous soild solution phases with the size of $50-100{\mu}m$ have been dispersed uniformly, and there is no reaction between aluminum and CrW alloy. In addition, after maintaining at high temperature of 573 K, there is no growth of hardening phase, nor desolved, but CrW still exists as a homogeneous solid solution.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.157-163
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• 2008

The HCCI combustion mode poses its own set of narrow engine operating by knocking. In order to solve this, inhomogeneity method of mixture and temperature is suggested. The purpose of this research is to get fundamental knowledge about the effect of thermal stratification on HCCI combustion of PRF -Air mixture. The temperature stratification is made by buoyancy effect in combustion chamber of RCM. The analysis items are pressure, temperature of in-cylinder gas and combustion duration. In addition, the structure of flames using the two dimensional chemiluminescence's images by a framing camera are analyzed. Under stratification, the LTR starting time and the HTR starting time are advanced than that of homogeneous. Further, the LTR period of homogeneous conditions became shorter than that of the stratified conditions. With the case of homogeneous condition, the luminosity duration becomes shorter than the case of stratified condition. Additionally, under stratified condition, the brightest luminosity intensity is delayed longer than at homogeneous condition.

• 대한수학회지
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• 제50권5호
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• pp.1033-1050
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• 2013

We show the existence of smooth isolated curves of different degrees and genera in Calabi-Yau threefolds that are complete intersections in homogeneous spaces. Along the way, we classify all degrees and genera of smooth curves on BN general K3 surfaces of genus ${\mu}$, where $5{\leq}{\mu}{\leq}10$. By results of Mukai, these are the K3 surfaces that can be realised as complete intersections in certain homogeneous spaces.

• 호남수학학술지
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• 제33권1호
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• pp.1-9
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• 2011

In this paper we study oscillatory integrals with analytic homogeneous phase functions for smooth radial functions. We give their sharp asymptotic behavior in terms of spherical Newton distance.

• Communications for Statistical Applications and Methods
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• 제15권5호
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• pp.793-798
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• 2008

Extreme value inference deals with fitting the generalized extreme value distribution model and the generalized Pareto distribution model, which are recently combined to give a single model, namely a two-dimensional non-homogeneous Poisson exceedance point process model. In this paper, we extend the two-dimensional non-homogeneous Poisson process model to include non-stationary effect or dependence on covariates and then derive the likelihood for the extended model.

• Journal of applied mathematics & informatics
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• 제8권1호
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• pp.71-80
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• 2001

The purpose of this paper is to give the classification of homogeneous integral table algebras of degree 5 containing a faithful real element of which 2. In fact, these algebras are classified to exact isomorphism, that is the sets of structure constants which arise from the given basis are completely determined. This is work towards classifying homogeneous integral table algebras of degree 5. AMS Mathematics Subject Classification : 20C05, 20C99.

• Journal of applied mathematics & informatics
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• 제8권2호
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• pp.569-580
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• 2001

In this paper, we obtain some results on the Hyers-Ulam stability for the family of the functional equation f(xоy) = $H(f(x)^{1/t},f(y)^{1/t}$) (x, $y{\in}S$), where H is a homogeneous function of degree t and о is a square-symmetric operation on the set S.