• Advances in concrete construction
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• 제5권6호
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• pp.587-611
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• 2017

This study focused on the influences regarding the use of polyepoxide-based polymer and silica fume (SF) on the fresh and hardened state properties of self-compacting lightweight concrete (SCLC) along with their impacts on electrical resistance and ultrasonic pulse velocity (UPV). To do so, two series of compositions each of which consists of twelve mixes, with water to binder (W/B) ratios of 0.35 and 0.4 were cast. Three different silica fume/binder ratios of 0, 5%, and 10% were considered along with four different polymer/binder ratios of 0, 5%, 10%, and 15%. Afterwards, the rupture modulus, tensile strength, 14-day, 28-day, and 90-day compressive strength, the UPV and the electrical resistance of the mixes were tested. The results indicated that although the use of polymer could enhance the passing and filling abilities, it could lead to a decrease of segregation resistance. In addition, the interaction of the SF and the polymeric contents enhanced the workability. However, the impacts regarding the use of polymeric contents on fresh state properties of SCLC were more prevalent than those regarding the use of SF. Besides the fresh state properties, the durability and mechanical properties of the mixes were affected due to the use of polymeric and SF contents. In other words, the use of the SF and the polymer enhanced the durability and mechanical properties of SCLC specimens.

• 한국초등수학교육학회지
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• 제15권2호
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• pp.247-282
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• 2011

7차 교육과정의 초등학교 수학교과서를 살펴보면 자와 컴퍼스를 사용하여 삼각형과 원을 그리며, 삼각자를 활용해 수직선과 평행선을 그리는 작도 교육이 이루어지고 있다. 본 연구는 2010년 초등학교 6학년 학생들의 작도 과정에서 나타나는 수학적 사고를 분석하여 초등학교 작도지도의 시사점을 제안하고자 한다. 연구결과 영재학급 6학년 학생들은 교사의 적절한 조언이 뒷받침되면 선분의 등분할 작도를 통해 유추, 연역, 발전, 일반화, 기호화의 사고와 같은 수학적 사고가 가능하며, 일반학급 학생들에게도 현행 교육과정보다 심화된, 자와 컴퍼스를 이용한 수직이등분선, 사각형, 마름모, 선분의 연장 등의 작도는 교육이 가능하다.

• 한국과학교육학회지
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• 제41권1호
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• pp.47-57
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• 2021

본 연구에서는 학습자의 인식적 행위주체성을 촉진하기 위하여 인식적 목표를 명시화하는 지식 구성 활동을 설계하여 초등 예비교사를 위한 생물학 강좌에 도입하였고, 이 활동에 참여한 예비교사들이 어떠한 유형의 인식적 목표를 어떻게 고안하였으며, 이 목표를 중심으로 정교한 수준의 인식적 특성을 지닌 지식 구성 활동이 형성되도록 촉진하거나 이를 제한한 요인을 탐색했다. 이를 위해 활동에 참여한 예비교사들의 실행 및 산출물을 녹음 및 수집했으며, 녹음 자료는 전사하여 본 연구의 분석 자료로 활용하였다. 분석 결과, 예비교사들이 고안한 인식적 목표의 유형은 '자연 현상에 대한 의미 형성하기', '실용적 선택안 제시하기', '문제 현상의 기작에 기반한 해결책 제시하기'로 도출되었다. 각 인식적 목표 유형은 예비교사들이 탐구하기로 선정한 자연 현상에 대한 지식을 바탕으로 어떠한 결론을 얻고자 하는가에 따라 서로 다르게 고안되었다. 예비교사가 인식적 목표를 명시화하는 활동 구조는 이들이 근거 기반의 지식 주장 정당화가 수반되는 지식 구성 활동을 고안하도록 촉진할 수 있는 것으로 분석되었다. 예비교사가 고안한 지식은 지식의 본성 측면에서 주로 현상에 관한 기술에 그쳤으며, 현상의 기작에 관한 설명 구성은 자연 현상이 일어나는 기작에 대한 의미를 형성하고자 하거나 현상의 기작에 대한 이해를 바탕으로 문제해결을 위한 해결책을 제시하고자 계획할 때 나타났다. 그러나 예비교사들이 활용 가능한 시간적·물리적 자원의 한계에 따라 기작에 대한 설명 산출 과정에서 정교한 수준의 인식적 특성을 지닌 지식 구성 활동이 제한될 수 있는 것으로 분석되었다. 본 연구는 학습자의 인식적 행위주체성을 촉진하는 교수학습 전략의 고안 및 인식적 행위주체성을 중심으로 한 예비교사 교육에 대한 논의에 기여할 수 있을 것으로 기대한다.

• 한국수학교육학회지시리즈A:수학교육
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• 제42권5호
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• pp.607-622
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• 2003

The research was aimed at finding the dynamic aspects of the linguistic and social interaction with mathematical concept development using a graphing calculator in collaborative learning. This study was broadly divided into two categories: "Knowledge Construction Statement" for understanding how the verbal interaction works when a graphing calculator is used, and "Teacher's Instructional Role" for the research on the reaction of the students and on the teacher's role as a guide in helping students to construct their knowledge. This research used a case study in a collaborative learning environment. An attempt was made to show clearly how the students interacted with one another in a technology environment using a graphing calculator as a tool. A graphing calculator promoted the students' linguistic interaction and changed the characteristics of the linguistic interaction. Although it didn't show the different aspects completely, some changes of the linguistic traits were perceived.aits were perceived.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제19권2호
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• pp.101-115
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• 2015

In the present paper, we argue any research concerning human knowledge construction, components, or types needs to clarify its epistemological stance regarding 'knowledge' in that such viewpoint might have much influence on the nature of knowledge the researcher sees and the way in which evidence for knowledge development is gathered. Thus, we suggest two alternative research groups who conducted their studies on mathematical knowledge for teaching with an explicit epistemological standpoint. We finalize our discussion by reviewing concrete examples in the previous literature on teacher knowledge of fraction conducted by the two groups.

• 수산해양교육연구
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• 제19권3호
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• pp.373-382
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• 2007

As the Internet users are growing, GIS researchers that would like to integrate various GIS informations have more interests for information searching technologies based on Web. But, even though these researches is growing a infinite possibility of utilizing the map, there are not yet providing more functionalized GIS services. This paper proposes a searching mechanism for the teacher information based on the SVG(Scalable Vector Graphics) format transformed the SHP format. We also implement the home-page link function inserted Web-connection information of the specific locations that could connect specific school web site within SVG file. We also provide the services to interpret requested query with proposed scheme.

• 아동학회지
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• 제19권2호
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• pp.115-132
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• 1998

The present study investigated the construction of the moral concepts of 3-, 4-, and 5- year old Korean children. Instruments were the Maternal Behavior Research Instrument by Schaefer for mother and feather nurturing attitudes, and the Domain Distinctiveness Model for children's moral judgments. Maternal and teacher attitudes were categorized by the affection-rejection factor consisting of affection-affection, affection-rejection, rejection-affection, and rejection-rejection dimensions, and by the permissive, -control factor consisting of permissive-permissive, permissive-control, control-permissive, and control-control dimension. Children's data were collected with an individualized interview in which children were asked to judge moral and social conventional transgression events. 30 children were assigned to each of the maternal/teacher attitude dimensions; thus, there were 120 children for each factor. Results showed that (1) the affection-affection cohort was must strongly related to moral rules using both the seriousness criterion and deserved punishment criterion, and (2) the permissive-permissive cohort was most strongly related to reasoning and action. However, this cohort did not break out of children's structural limitation (limited responses to the intangible).

• Advances in concrete construction
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• 제5권2호
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• pp.87-99
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• 2017

After passing through a magnetic field, the physical quality of water improves, and magnetic water (MW) is produced. There are many investigations on the effects of magnetic field on water that shows MW properties like saturation and memory effect. This study investigates the fresh and hardened properties of concrete mixed with MW, which contains silica fume (SF) and superplasticizer (SP). The test variables included the magnetic field intensity for producing MW (three kinds of water), SF content replaced cement (0 and 10 percent), water-to-cementitious materials ratio (W/CM=0.25, 0.35 and 0.45) and curing time (7, 28 and 90 days). The results of this study show that MW had a positive impact on the workability and compressive strength of concrete. By rising the intensity of the magnetic field which was used for producing MW, its positive influence on both workability and compressive strength improved. MW had greater positive impacts on samples containing SP that did not have SF. Moreover, the best compressive strength improvements of concrete achieved as W/CM ratio decreased.

• 한국과학교육학회지
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• 제24권1호
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• pp.90-108
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• 2004

This study is to understand preservice science teachers' previous experience, beliefs about teaching and learning, and visions of themselves as future teachers. The data were collected from two individual interviews with 7 voluntary students and analyzed qualitatively for category construction. As the results of this study, we presented two cases, which showed that their different views of teaching science are strongly related to their previous experiences as learners and observers in schools, and that there is the apparent consistency between each participant's beliefs about science teaching and learning and their own visions of teaching in a science classroom. Implications for preservice science teacher education related to the results were discussed.

• Advances in concrete construction
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• 제4권4호
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• pp.305-317
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• 2016

Porous materials such as concrete could be subjected to aggressive ions transport. Durability of cement paste is extremely depended on water and ions penetration into its interior sections. These ions transport could lead different damages depending on reactivity of ions, their concentrations and diffusion coefficients. In this paper, chloride diffusion process in cement hydrates is simulated at atomistic scale using molecular dynamics. Most important phase of cement hydrates is calcium silicate hydrate (C-S-H). Tobermorite, one of the most famous crystal analogues of C-S-H, is used as substrate in the simulation model. To conduct simulation, a nanopore is considered in the middle of simulation cell to place water molecules and aggressive ions. Different chloride salts are considered in models to find out which one is better for calculation of the transport properties. Diffusion coefficients of water molecules and chloride ions are calculated and validated with existing analytical and experimental works. There are relatively good agreements among simulation outputs and experimental results.