• The Mathematical Education
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• v.55 no.3
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• pp.317-334
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• 2016

Knowledge and data interpretation on statistical estimation was important to have statistical literacy that current curriculum was said not to satisfy. The author investigated mathematics teachers' MKT on statistical estimation concerning interpretation of confidence interval by using questionnaire and interview. SMK of teachers' confidence was limited to the area of textbooks to be difficult to interpret data of real life context. Most of teachers wrongly understood SMK of interpretation of confidence interval to have influence upon PCK making correction of students' wrong concept. SMK of samples and sampling distribution that were basic concept of reliability and confidence interval cognized representation of samples rather exactly not to understand importance and value of not only variability but also size of the sample exactly, and not to cognize appropriateness and needs of each stage from sampling to confidence interval estimation to have great difficulty at proper teaching of statistical estimation. PCK that had teaching method had problem of a lot of misconception. MKT of sample and sampling distribution that interpreted confidence interval had almost no relation with teachers' experience to require opportunity for development of teacher professionalism. Therefore, teachers were asked to estimate statistic and to get confidence interval and to understand concept of the sample and think much of not only relationship of each concept but also validity of estimated values, and to have knowledge enough to interpret data of real life contexts, and to think and discuss students' concepts. So, textbooks should introduce actual concepts at real life context to make use of exact orthography and to let teachers be reeducated for development of professionalism.

• School Mathematics
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• v.12 no.4
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• pp.493-506
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• 2010

In this study, we conducted classroom activities that are exploring and explaining visualized materials for problem solving of school mathematics with pre-service teachers in 2007~2009. After finishing these classroom activities, pre-service teachers recorded an afternote that includes changes of their thinking about mathematics and mathematics education through these activities in this study. We collected various opinions of pre-service mathematics teachers. From the analysis these data, we searched educational effects of our classroom activities. Through conducting the practice like these classroom activities of our study, pre-service mathematics teachers will have an opportunity of a practical training that supports the teaching of mathematical problem-solving. Moreover their PCK will be enhanced. Also, They will learn a good way to realize the aim of school mathematics curriculum.

• Journal of Practical Engineering Education
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• v.13 no.2
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• pp.293-300
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• 2021

The aim of this study was to measure preservice teachers' perceptions of Technological Pedagogical Content Knowledge (TPACK). The researcher analyzed responses on the TPACK scale of 307 students in A University located in Chungcheongbuk-do. During the statistical analysis, IBM SPSS 21 program was used to implement Independent Samples T-test, One-way Analysis of Variance, and Multiple Regression Analysis (Enter method). The results are as follows. First, for the mean difference by gender, the mean of female students was higher than that of male students in Pedagogical Knowledge, Pedagogical Content Knowledge, Technological Pedagogical Knowledge, and Technological Pedagogical Content Knowledge. Second, for the mean difference by grade level, the mean of the 1^st, 3^rd and 4^th graders was higher than that of the 2^nd graders in the Content Knowledge at a statistically significant level. Third, toward Technological Pedagogical Content Knowledge, Pedagogical Knowledge of .11 beta value, Pedagogical Content Knowledge of .11 beta value, and Technological Pedagogical Knowledge of .715 beta value were found to be statistically significant predictors. Finally, the researcher discussed development of the TPACK implementation manual and workbook and provision of various technology practice opportunities.

• Journal of the Korean Chemical Society
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• v.66 no.6
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• pp.459-471
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• 2022

The purpose of this study is to develop the workshop to improve teachers' questions considering the context of discourse. Four pre-service science teachers in the fourth grade participated in the study. Pre-service science teachers participated in the workshop. The characteristics of their reflection on the question considering the context of discourse were analyzed. Pre-service science teachers considered the types of questions they learned in the workshop during the reflection. But the affective domains of students were rarely considered. Whether the students respond was considered as an important factor of reflection. The questions were evaluated based on the frequencies. A single question without context was reflected on. Various PCK elements were not considered comprehensively. Based on the results, the practical implications to develop a program for improving teacher expertise related to the questions considering the context of discourse were discussed.

• The Mathematical Education
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• v.45 no.1 s.112
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• pp.75-96
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• 2006

The purpose of this study was to analyze how elementary pre-service teachers learned the pedagogical content knowledge of mathematics and to understand the challenges and difficulties that they experienced in the course of student teaching. A qualitative case study provided an in-depth description of the whole three weeks of student teaching process. Four pre-service teachers and two mentor teachers participated in this study. Multiple data collection techniques were used; classroom observations, in-depth interviews, document analysis, and researcher's field notes. The results of this study showed how pre-service teachers learn PCK of mathematics in designing mathematics lessons, understanding mathematics learners and delivering mathematics lessons and what are the difficulties and challenges they experienced. Finally this study discussed about some suggestions to pre-service program and future research.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.05a
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• pp.121-124
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• 2001

Using ordors with the different concentration of essential oils, e studied the effect of a pleasant olfactory stimulation on physiological responses. we examined psychological response, mental task and changes in cardiac, immunity and EEG in responses to 150times solution (feel easily) and 500times solution (feel with difficulty) which of essential oil (called PCK) were diluted in propylene glycol, and neutral (water). The 150times solution that was felt pleasant produced significant differences (p<0.05) in relative power change of beta activity in the left frontal region (Fp1, F3, F7) of the brain, and heart rate (HR) deceleration after mental task. these results are consistent with substantial research that has documented cardiac and EEG responses to pleasant stimuli. What is more, 150times solution increased the concentration of s-IgA know as an index of immunity.

• Korean Journal of Human Ecology
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• v.21 no.4
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• pp.629-647
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• 2012

This study explored what Korean college students, especially preservice teacher in early childhood education, experienced and how they constructed the meanings of experiences about their subject- matter course (early childhood mathematics education) taught in English. One cohort- 20 senior students- majoring in early childhood education in a 4-year university was participated in this study. Using action research method and narrative research method, data were analyzed. The findings were as follows: 1) preservice teacher experienced some difficulties to construrct professional knowledge through English. 2) They challenged to overcome these difficulties through active participation. 3) They got supports from instructor and peer group. 4) They accomplished the course with self-satisfaction. 5) They experienced the conflicts between social requirements and personal needs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.249-252
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• 1997

Electroluminescence(EL) devices based on organic thin layers have attracted lot of interests because of their possible application as large-area display-emitting display. One of the problems of such devices is lifetime of the cell, where the degradation of the cell is partially due to the crystalliyzation of organic layers. In large part, this problem can be solved by using a multilayer device structure prepared by vapor deposition technique. In this study, blue light-emitting multilayer organic electroluminescence devices were fabricated vsing Poly (9-vinylcarbaEole) (PVK) and 2- (4-tert-butylphenyl)-5-(4$^{#}$-bis-phenyl) 1,3,4-oxadiazole (PBO) as hole trasport and electron transport material, respectively, where trim(8-hyd roxyquinolinate) aluminum (Al $q_3$) was used as a luminescenct material. A cell structure of glass sub- strate/indume-tin-oxide(ITO)/PCK/Al $q_3$/PBD/Mg:In was employed. Blue emission peak at 510nm was observed with this cell structure.e.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.229-230
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• 2017

테크놀로지의 중요성이 증가함에 따라 교사와 예비 교사의 테크놀로지 관련 지식의 중요성이 증가하고 있다. 이에 따라 예비 교사의 TPACK을 향상시키기 위한 다양한 연구가 진행되고 있다. 본 연구에서는 프로그래밍을 접목한 TPACK-P 모델을 기반으로 개발한 교육 프로그램을 예비 교사에게 적용하고, 예비 교사의 TPACK 변화를 관찰하였다. 교육 프로그램의 적용은 K 대학의 2016년 2학기 강의의 일부로 진행하였으며, 연구 대상은 수업을 수강하는 예비 교사 19명이었다. 교육 프로그램을 적용하기 전과 후에 박기철과 강성주(2014)의 검사 도구를 활용하여 예비 교사의 TPACK을 측정하였고, 대응 표본 t-검정을 통하여 예비 교사의 TPACK 변화를 통계적으로 분석하였다. 분석한 결과, TPACK-P 기반 교육 프로그램은 예비 교사의 TPACK 발달에 효과적인 것으로 나타났다. 세부 영역에서는 PCK를 제외한 모든 영역에서 통계적으로 유의미한 차이가 나타났다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.191-192
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• 2012

옥외 LED 조명은 수 많은 응용 분야가 있고, 출력 전력 크기에 따라 전력단이 single-stage 와 two-stage 구조로 나뉜다. Single-stage 구조는 낮은 전력 LED 조명에 적합하지만, 60~70W 이상에서는 효율이 떨어지고 변압기의 크기가 커져서 적용하기가 힘들다. 반면에 two-stage 구조는 보통 큰 전력이 필요한 응용분야에 사용되지만, 낮은 부하에서 낮은 역율을 나타내므로 넓은 출력전력 범위를 갖는 분야에 사용되기 어렵다. 이 문제를 해결하기 위하여 본 논문은 pulse duty cycle, pulse frequency modulation 제어 방법을 갖는 interleaved single-stage flyback AC-DC converter 를 제안한다. 제안된 컨버터는 입력 전압이 낮고 부하가 큰 경우 높은 효율을 보이고, 입력 전압이 높고 부하가 아주 작은 경우에도 높은 역율과 낮은 전류 왜곡을 보인다. 그 결과 하나의 AC-DC 컨버터를 넓은 출력전력 범위를 갖는 LED 조명분야 적용시킬 수 있다. 제안된 컨버터의 타당성을 검증하기 위하여 81W prototype을 가지고 실험하였다.