• 한국과학교육학회지
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• 제27권9호
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• pp.870-880
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• 2007

이 연구에서는 과학실험활동에서 이루어지는 학습자의 상호작용 과정을 심층적으로 분석함으로써,인지수준별 모둠구성에서 나타나는 상호작용의 변화형태와 특성을 확인하여 상호작용 과정에 대한 실질적 이해를 돕고자 하였다. 이를 위해 1년 동안 13개의 탐구실험 활동이 진행되는 동안 교사가 추천한 두 모둠을 관찰 하면서 녹음/녹화하였다. 40차시의 녹음/녹화자료는 모두 전사되었으며,자료는 메모하면서 보고 듣는 과정을 반복하는 방법을 기초로 분석하였다. 이질모둠의 상호작용은 3A(형식적조작초기)학생이 문제해결을 주도하고 나머지 학생들은 상호작용에 참여하지 못한 채 일방적인 설명을 듣거나 답을 베끼는 식으로 변화하였다. 한편 낮은 능력의 학생은 상호작용에서 소외되고 있었으며,중간수준의 두 학생사이에 새로운 상호작용이 형성되고 있었다. 이로부터 상호작용을 강조한 활동의 진행과 모둠구성에 대한 시사점을 얻을 수 있었으며,이에 대해 논의하였다.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2419-2421
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• 2009

A simple and efficient method has been developed for Knoevenagel condensation between aldehydes or ketones and active methylene group by stirring in methylene chloride at 60 ${^{\circ}C}$ under heterogeneous conditions using silica supported ammonium acetate. The products are obtained in excellent yields and are in a state of high purity. The structures of the products were confirmed by IR, $^1H$ NMR and mass spectral data and comparison with authentic samples available commercially.

• 청정기술
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• 제22권4호
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• pp.250-257
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• 2016

As an attempt to replacing petroleum-based chemicals with bio-based ones, synthesis of furfural from biomass-derived xylose attracts much attention in recent days. Conventionally, furfural from xylose has been produced via the utilization of highly corrosive, toxic, and environmentally unfriendly mineral acids such as sulfuric acid or hydrochloric acid. In this study, microwave-assisted biphasic reaction process in the presence of novel bio-based heterogeneous acid catalysts was developed for the eco-benign and effective synthesis of furfural from xylose. The microwave was irradiated for reaction acceleration and a biphasic system consisting of $H_2O$ : MIBK (1 : 2) was designed for continuous extraction of furfural into the organic phase in order to reduce the undesired side products formed by decomposition/condensation/oligomerization in the acidic aqueous phase. Moreover, sulfonated amorphous carbonaceous materials were prepared from wood powder, the most abundant lignocellulosic biomass. The prepared catalysts were characterized by FT-IR, XPS, BET, elemental analysis and they were used as bio-based heterogeneous acid catalysts for the dehydration of xylose into furfural more effectively. For further optimization, the effect of temperature, reaction time, water/organic solvent ratio, and substrate/catalyst ratio on the xylose conversion and furfural yield were investigated and 100% conversion of xylose and 74% yield of furfural was achieved within 5 h at $180^{\circ}C$. The bio-based heterogeneous acid catalysts could be used three times without any significant loss of activity. This greener protocol provides highly selective conversion of xylose to furfural as well as facile isolation of product and bio-based heterogeneous acid catalysts can alternate the environmentally-burdened mineral acids.

• Journal of applied mathematics & informatics
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• 제8권3호
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• pp.919-934
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• 2001

The concepts of material frame-indifference and material symmetry group with respect to isotropic scalar functions, as represented by energy functions, are discussed. An energy function for a structured heterogeneous (transversal isotropic) medium in large elastic deformations, which is known to satisfy the Ponyting’s effect [1], is highlighted. It is shown that the constitutive relation due to this energt function is material frame-indifferent.

• 전자공학회논문지B
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• 제33B권7호
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• pp.51-59
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• 1996

The current network environment is composed of heterogeneous H/W and S/W resources. Integrating CSCW applications in such heterogeneous environments is highly complex. This paper describes the design and implementation of ASS (application sharing server) which supprot sharing of a single application between different operating systems. The ASS supports cooperative work among user group using its own window system (X-windwo or MS-windwos). We adopted improved managing heavy-weight data. ASS also provides development environment for vaious groupware application.

• 한국과학교육학회지
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• 제21권4호
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• pp.668-676
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• 2001

이질적으로 구성된 소집단 협동학습에서의 내적 과정을 이해하기 위해서 이 연구에서는 과학 수업에서의 협동학습 과정에서 나타나는 성취 수준별 상호작용 양상을 조사하였다. 성취 수준별 언어적 행동의 빈도를 비교하여 언어적 상호작용에의 참여 정도 및 방식을 조사하였다. 그리고 상호작용에 대한 학생들의 인식을 조사하여 성취 수준에 따른 상호작용 양상도 분석하였다. 조사 결과, 상위와 중위 학생 사이에는 언어적 행동의 빈도에 차이가 없었으며, 소집단의 언어적 상호작용은 상위와 중위 학생이 서로 협력하여 공동으로 의미를 구성해나가는 방식으로 일어났다. 상위와 중위 학생 사이의 활발한 상호작용은 학생들의 인식 조사를 통해서도 확인되었다. 즉, 과학수업에서의 협동학습 과정에서는 중위 학생도 적극적이고 활발하게 소집단 활동에 참여하고 있었다.

• Journal of the Korean Statistical Society
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• 제36권1호
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• pp.129-148
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• 2007

Frailty estimates from the proportional hazards frailty model often lead us to conjecture the heterogeneity in frailty such that the variance of the frailty varies over different covariate groups (e.g. male group versus female group). For such systematic heterogeneity in frailty, we consider a regression model for the variance components in the proportional hazards frailty model, denoted by the MLFM. However, in many cases, the observed data do not show any statistically significant preference between the homogeneous frailty model and the heterogeneous frailty model. In this paper, we propose a Bayesian model averaging procedure with the reversible jump Markov chain Monte Carlo which selects the appropriate model automatically. The resulting regression coefficient estimate ignores the model uncertainty from the frailty distribution in view of Bayesian model averaging (Hoeting et al., 1999). Finally, the proposed model and the estimation procedure are illustrated through the analysis of the kidney infection data in McGilchrist and Aisbett (1991) and a simulation study is implemented.

• 한국초등과학교육학회지:초등과학교육
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• 제38권1호
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• pp.1-15
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• 2019

This study aimed to identify the effects of students' empathy ability on group creativity, when elementary school students perform scientific activity designed to express group creativity. A total of 12 elementary students from a fifth-grade science club participated in this study. A pretest to examine the students' empathic ability was performed to classify them into three groups: A group with high, low and heterogeneous empathic members. The linguistic interaction was analyzed to determine the process of group creativity manifestation; the results were classified into 'metacognitive', 'cognitive', and 'social-communicative'. As a result, groups with high empathic ability showed more frequent interaction in monitoring, planning, and divergent thinking. On the other hand, in the case of the group with low level of empathy, it was confirmed that there are many interactions related to regulation, convergent thinking, and noncohesive prosocial interaction. Also, in the case of heterogeneous group with empathy ability, group creativity utterance on all sides was relatively higher than other groups. As a result of this study, we could confirm the influence of empathy as a strategy to help the group creativity and discuss the educational implications.

• 한국가정과교육학회지
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• 제12권1호
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• pp.47-58
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• 2000

The purpose of this study is to investigate the effects of cooperative learning method on student achievement and attitude in Home Economics. and that what sort of effectiveness be existed between the two groups. Homogeneous & Heterogeneous one in achievement. A junior middle school in Kwangju was served for the study. Setting two groups: One is for cooperative learning and other for traditional learning. Two classes were provided with cooperative learning method. while one class with traditional learning method. Two hours of a week were devoted for the experiment. and it was also planned to be lasted six weeks from the third of June. 1998. until the 13th of July. 1998. The results are as follows: 1) Student achievement from cooperative learning method showed a little higher than those from traditional learning method. 2) Cooperative learning method was more effective than traditional learning method. mental attitude toward school. lessons and teachers were more higher than those the traditional learning method. 3) The group of Heterogeneous members was higher than the group of Homogeneous members in their student achievement. 4) It is noticeable that two groups under cooperative learning method. however showed some difference when each of them is placed in different organization. The group of Heterogeneous members was more affirmative attitude toward school. lessons and teachers than the one Homogeneous members.

• 한국수학교육학회지시리즈A:수학교육
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• 제54권4호
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• pp.335-350
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• 2015

The purpose of this study was to investigate the effectiveness of the differentiated instruction in mathematics by a meta-analysis. Among the studies conducted for last twenty three years, the relevant 49 research articles were selected, 80 effect sizes were calculated for the cognitive domain and 70 effect sizes for the affective domain. Effect sizes were analyzed with school levels, student level, group organization method such as homogeneous vs. heterogeneous, class transfer and adjusting class sizes for each cognitive domain and affective domain. The results are as the followings: In the cognitive domain, the overall effect size of the differentiated instruction produced a medium effect(effect size=0.68, U3=75.17%). The differentiated instruction showed the highest effect size on elementary school and middle school, mid level students, heterogeneous group, class transfer and not adjusted class size. And in the affective domain, the overall effect size of the differentiated instruction produced a low effect(effect size=0.36, U3=65.36%). The differentiated instruction showed the highest effect size on elementary school, mid level students, and heterogeneous group. Thus the differentiated instruction was proved to be effective in mathematics classes.