• Magazine of the Korea Concrete Institute
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• v.9 no.6
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• pp.195-206
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• 1997

산업폐기물인 폐주물사를 재활용하여 에너지절감과 환경오염방지효과를 얻을 수 있다. 반요인실험법을 사용하여 폐주물사를 잔골재에 일정비율 치환한 콘크리트의 적정배합설계제시를 위한 예비실험에서 물-시멘트비, 폐주물사의 잔골재치환율, 잔골재율, 슬럼프와 같은 주요변수와 변수사이의 2차상호작용을 파악하였다. 예비실험결과 폐주물사의 잔골재치환율 70%까지 실시하였을 때 폐주물사를 혼입한 콘크리트의 강도 발현에 가장 중요한 변수는 물-시멘트비로 분석되었고 폐주물사의 잔골재치환율은 거의 영향이 없는 것으로 분석되어 폐주물사를 콘크리트의 잔골재로 대체할 수 있음을 알 수 있었다. 각 변수의 2차상호작용에서는 폐주물사의 잔골재치환율과 잔골재율의 상관관계가 콘크리트의 강도발현에 가장 큰 영향을 미치는 것으로 나타났다. 목표압축강도에 대한 적정배합조건을 폐주물사의 잔골재 치환율에 따라 물-시멘트비, 잔골재율에 대해 제시하였다.

• Journal of the Korean Chemical Society
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• v.60 no.4
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• pp.276-285
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• 2016

This study aimed to examine preservice science teachers' modeling ability and how it has changed in argument-based chemistry laboratory investigations. The participants for this study were twenty-one freshman students from teachers’ college and they carried out six topics of argument-based chemistry laboratory investigation. Students’ written modeling samples were collected and analyzed to investigate preservice science teacher's modeling ability and changes in it. The results of this study showed that preservice science teacher's modeling ability has improved and progressed through argument-based chemistry laboratory investigations.

• Journal of The Korean Association For Science Education
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• v.26 no.7
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• pp.826-834
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• 2006

The purpose of this study is to examine the pre-service teachers' concept of measurement uncertainty. The subject of this study were 27 pre-service middle-school teachers in Seoul. They carried out open-ended inquiry tasks and surveyed two kinds of open questionnaires, and interviewed several persons. We analysed their behavior and responses. Through the analysis, we summarize pre-service teachers' concept about measurement uncertainty with representation data, precision and accuracy, error analysis, propagation of uncertainty. The results show that the teachers' concept is different from scientists' concept. They make a mistake in using term of precision and accuracy and pay no attention to measure precisely. Also they only point out sources of error but don't consider how the error affects the results of experiment. The results of study will give! 1 some implications for the curriculum and teaching material developers in order that pre-service teacher and student gain scientific concept.

• Journal of the Korean Chemical Society
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• v.62 no.1
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• pp.52-63
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• 2018

The purpose of this study was to observe and analyze how pre-service secondary chemistry teachers conduct open-ended, free style, exploratory chemistry experiments. The study examined common difficulties and tendencies that teachers showed in the chemistry labs. The study also investigated how these teachers deal with their difficulties and obstacles, such as unexpected results and device errors. Next, the study explored how students' epistemic goals and considerations have been shaped and changed as they interacted with one another and participated in their experiments over time. The study suggests that it could be more effective to gradually decrease guided-features of the experiment by providing appropriate scaffolding, than to start with completely open-ended inquiry labs. The study also suggests that the establishment of epistemic agency among group members influences the way they conduct experiments. Consequently, it is necessary to consider how instructional design for open-ended inquiry labs may provide students with scaffolds to encourage their active participation and to build responsibility in group discussions.

• Journal of Science Education
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• v.35 no.1
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• pp.80-90
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• 2011

The purpose of this study is to investigate manual skills of experimental apparatuses of pre-service elementary school teachers by examining and analyzing the process of experiments conducted by pre-teachers. For this study, 24 pre-service elementary school teachers were selected as the subjects and 4 experimental apparatuses were chosen through analyzing science textbooks from 3rd grade to 6th grade in elementary school. The selected experimental apparatuses were alcohol burner, dropper, microscope, instruments for making a prepared specimen. In addition, a task was carefully chosen to conduct an investigation in real settings and a series of evaluation standards was developed. While 3 subjects conducted experiments in separated and independent space at the same time, 3 collaborators observed the experiment process and recorded whether the subject met the evaluation standards or not, using O, X. The study suggests that pre-service elementary school teachers' manual skills of experimental apparatuses were under far below our projections. Particularly, in case of alcohol burner, the subjects showed lower ability to properly light the burners - which is to brush through the lampwick with fire - and to adjust the height of tripods according to the flame. Also, when it comes to dropper, they were not held the way they were supposed to be. In addition, when designing prepared specimen, the subjects used their hands instead of tweezers and often skipped the process of dripping water drop and wiping water with an oilpaper. Moreover, they did not know how to use a microscope properly so there were many times that they could not focus a microscope, failing to observe the objects. Educational implications are discussed.

• Journal of the Korea Society of Computer and Information
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• v.25 no.7
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• pp.213-224
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• 2020

This study analyzes the effects of programming-based TPACK education programs, designed by Kim and Lee (2019), on the teaching expertise of pre-service teachers. The research subjects were 40 pre-service teachers, divided into an experimental group and a control group. The experimental group underwent the programming-based TPACK education program, and the control group used an ICT-based TPACK education program. A test tool was used to measure not only teaching expertise but also teaching efficacy and self-efficacy beliefs about technology integration. As a result of the study, teaching expertise, teaching efficacy, and self-efficacy beliefs about technology integration improved significantly in the experimental group. The pretest showed no significant difference between the experimental group and the control group, but in the post-test, the experimental group showed significantly higher teaching expertise than the control group. These results showed that the programming-based TPACK education program is effective for developing teaching expertise in pre-service teachers.

• Journal of The Korean Association For Science Education
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• v.41 no.6
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• pp.519-531
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• 2021

This study investigates the science teacher identity of pre-service science teachers (PSTs) in the context of a teaching practice course. Twenty-two PSTs who took the 'Biological Science Lab. for Inquiry Learning' course at the College of Education participated in this study. Artifacts created during the course were collected, and the teaching practices and reflections were recorded and transcribed. In addition, semi-structured interviews were conducted with nine PSTs, recorded, and transcribed. We found the science teacher identity was not well revealed at the beginning of the course. Authoritative discourse appeared in the early oral reflections of PSTs, indicating that the PSTs perceived oral reflection activities as 'evaluation activities for teaching practice'. This perception shows that pre-service teachers participate in teaching practice courses as students attending a university, performing tasks and receiving evaluations from instructors. After the middle of the course, discourses showing the science teacher identity of the PSTs were observed. In the oral reflection after the middle part, dialogic discourses often arose, showing that the PSTs perceive the oral reflection activities as a 'learning activity for professional development'. In addition, in the second half, discourse appeared to connect and interpret one's experience with the teacher's activity, indicating that the PSTs perceive themselves as teachers at this stage. In addition, the perception of experimental classes was expanded through the course. During the course, the practice of equalizing the authority of the participants, providing a role model for reflection, and experiencing various positions from multiple viewpoints in the class had a positive effect on the formation and continuation of the teacher identity. This study provides implications on the teacher education process for teacher identity formation in PSTs.

• Journal of the Korean Chemical Society
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• v.66 no.2
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• pp.150-162
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• 2022

In this study, we investigated pre-service science teachers' NOS-PCK by analyzing their NOS lesson planning and demonstration. Four pre-service science teachers participated in the study. They planned and demonstrated NOS lessons in the context of 'Science Inquiry Experiment' developed under the 2015 Revised National Curriculum. Their lessons were observed. All of the teaching-learning materials were collected, and semi-structured interviews were also conducted. The analyses of the result revealed that pre-service teachers mainly referred to the curriculum and textbooks when selecting the NOS learning objectives. However, they felt difficulty because the curriculum and textbooks did not clearly present the NOS to be dealt. Although all of them took explicit approaches, there were not many open and divergent reflective approaches. In addition, they expected that high school students would consider scientific knowledge absolute and would have negative perceptions of NOS lessons. They rarely assessed students' NOS learning, and were reluctant to assess. Finally, most of them had a negative perception that learning NOS is not necessary for all students. On the bases of the results, educational implications for improving the expertise of pre-service science teachers in NOS lessons were discussed.

• Journal of the Korean Chemical Society
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• v.65 no.6
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• pp.441-454
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• 2021

In this study, pre-service science teachers' difficulties in teaching practice were investigated from the perspectives of pre-service teachers and cooperating teachers. Nine pre-service teachers who were attending a department of chemistry education at a college of education in Seoul and participated in teaching practice, and two of their cooperating teachers participated in the study. Teaching practice were observed, documentary data were collected, and interviews were conducted. The collected data were analyzed using analysis method of grounded theory. As results of the analysis, the pre-service teachers had difficulties in preparing and executing lessons which include experiments, because education related to experiments in middle and high schools was insufficient at the college of education and environments of cooperating school were unfamiliar to them. They had difficulties in encountering various responses from students in student-centered activities and tried to control students. Cooperating teachers did not provide specific assistance to ensure the autonomy of pre-service teachers, so that pre-service teachers suffered. Guiding science club activities was a meaningful experience to pre-service teachers, but it was a burden on both pre-service teachers and cooperating teachers. Educational implications of these findings were discussed.

• Journal of the KSME
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• v.32 no.6
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• pp.524-535
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• 1992

형단조 제품의 예비성형체의 결정이 중요하며, 그 형상은 최종 제품의 설계 조건에 따라서 수 치적으로 결정될 수 있음을 알았다. 축대칭이나 평면 변형과 같은 2차원 해석이 필요한 제품의 경우에는 체계적인 방법으로 예비성형체의 모양을 결정할 수 있으며, 그 결과를 이용하여 일련의 단조 공정이 설계된다. 이러한 수치해석적 설계 방법은 단조에서 CNE의 근간이 되어 설계의 자동화에 직접적으로 기여할 수 있을 것이다. 이 분야에서 앞으로의 연구방향은 기존에 확립되어 있는 수치해석적 설계방법을 보편화하여 현장에서 사용하기 쉽도록 패키지화할 것과, 모형실험 또는 실제 공정을 통한 해석결과 및 설계를 검증할 것 등이다. 또한, 일반 3차원 형단조의 공정 해석도 활발하게 이루어져 복잡한 정밀 단조에 대한 설계 자동화도 연구되어야 할 것이다.