• Journal of The Korean Association For Science Education
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• v.44 no.5
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• pp.361-378
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• 2024

This study explores elementary teachers' PCK change through the knowledge exchange between ePCK (enacted PCK) and pPCK (personal PCK) during modeling-based science inquiry instruction. For this purpose, three elementary school teachers were selected as research participants, and the CoRes(content representations) written by the participants before and after the lessons. The CoRes were, then, analyzed using qualitative content analysis to explore changes in pPCK, and the data related to the modeling-based science inquiry instruction (such as lesson plan, lesson videos, in-depth interviews) were analyzed using grounded theory research methods. The research indicated that the pPCK of elementary teachers who enacted modeling-based science inquiry instruction changed in regard to curricular knowledge, knowledge of students, pedagogical knowledge, and assessment knowledge. The data from the modeling-based science inquiry instruction showed that the changes of the teachers' pPCK was influenced by the knowledge exchange between ePCK and pPCK during the process of planning, teaching, and reflecting on the lessons. Based on the findings, this study discussed the need to identify personal factors that influence elementary teachers' knowledge exchange between PCK realms and suggested the need to develop effective modeling-based science inquiry teaching methods.

• Journal of The Korean Association For Science Education
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• v.44 no.1
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• pp.105-117
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• 2024

The purpose of this study was to explore changes in elementary teachers' modeling pPCK (personal PCK) resulting from knowledge exchange within the realms of PCK described in the Refined Consensus Model (hereafter RCM). For this purpose, a professional learning community (hereafter PLC) was established for three elementary school teachers to facilitate knowledge exchange specifically focused on science modeling instructions. The study then analyzed the CoRe (content representations) written by the research participants twice to explore any changes in modeling pPCK (personal PCK). In addition, the discourse shared by the participants in the PLC and the data from the in-depth interviews were also analyzed using grounded theory research methods. The results of the study showed that there was no significant change in knowledge of the science curriculum in elementary teachers' modeling pPCK, but there were changes in orientations toward teaching science, knowledge of students' understanding in science, knowledge of instructional strategies and representations, and knowledge of assessment of science learning. Furthermore, the analysis of PLC discourse and in-depth interviews showed that modeling instructions reflection (ePCK; enacted PCK) and educational research-based modeling cPCK (collective PCK) influenced these changes in teachers' modeling pPCK. Accordingly, this study suggests recommendations for pedagogical approaches aimed at improving teachers' modeling PCK.

• Journal of Korean Elementary Science Education
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• v.43 no.1
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• pp.95-107
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• 2024

In this study, we explored the mediating effect of grit in the relationship between elementary school science teachers' perceived personal pedagogical content knowledge (pPCK) and enacted pedagogical content knowledge (ePCK). Drawing on insights from a review of the literature, we developed a research hypothesis model that set pPCK, ePCK, and grit as latent variables. Pearson correlation was conducted to examine the interrelationships among the latent variables. Structural equation modeling (SEM) was then employed to analyze the model fit. Additionally, bootstrap analysis was performed to specifically investigate the mediating effect of grit in the relationship between pPCK and ePCK. The Pearson correlation analysis indicated statistically significant correlations among the measurement variables. Meanwhile, the SEM analysis revealed that the measurement model aligned with the research hypothesis model. Furthermore, the bootstrap analysis demonstrated that grit had a statistically significant mediating effect in the relationship between elementary school science teachers' perceived pPCK and ePCK. These findings quantitatively examine the importance and impact of grit in the teacher expertise domain, providing valuable insights for the development of teachers' expertise and teacher education research within elementary school science classes.

• Journal of The Korean Association For Science Education
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• v.32 no.8
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• pp.1378-1389
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• 2012

Environmental education is usually taught across the curriculum in most of the countries. This teaching approach has been a challenge for teachers to implement it especially in the Malaysian curriculum context. Thus, science teachers require effectual Pedagogical Content Knowledge of Environmental Education (PCK-EE). The purpose of this study was to explore the influence of teaching option and teaching experience on science teachers' PCK-EE. Five components of PCK-EE were investigated in this study, which were: a) knowledge of curriculum, b) knowledge of content, c) knowledge of student, d) knowledge of teaching strategies, and e) knowledge of evaluation. 347 secondary science teachers from the state of Selangor have participated in this survey study. The questionnaire used had 60 items. The findings revealed teaching option has a significant influence on science teachers' knowledge of content (p=0.000); knowledge of student (p=0.000) and knowledge of teaching strategies (p=0.016). In the case of teaching experience, it was found that there is a low correlation on knowledge of content (r=0.174) and knowledge of evaluation (r=0.170) only. Implication of this study leads to the suggestion in enhancing teachers' service training to improve their PCK-EE and subsequently their ability in teaching environmental education across curriculum.

• Journal of Microbiology and Biotechnology
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• v.26 no.8
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• pp.1452-1456
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• 2016

Overexpression of the genes encoding phosphoeneolpyruvate carboxykinase (pckA) and NAD-dependent malic enzyme (maeA) facilitates higher intracellular ATP and NAD(P)H concentrations, respectively, under aerobic conditions in Escherichia coli. To verify a hypothesis that higher intracellular energy reserves might contribute to H₂ fermentation, wild-type E. coli strains overexpressing pckA and maeA were cultured under anaerobic conditions in a glucose minimal medium. Overexpression of pckA and maeA enabled E. coli to produce 3-times and 4-times greater H₂ (193 and 284 nmol, respectively) than the wild type (66 nmol H₂). The pckA and maeA genes were further overexpressed in a hydrogenase-3-enhanced E. coli strain. The hydrogenase-3-enhanced strain (W3110+fhlA) produced 322 nmol H₂, whereas the ATP-enhanced strain (W3110+fhlA+pckA) produced 50% increased H₂ (443 nmol). Total H₂ in the NAD(P)H-enhanced strain (W3110+fhlA+maeA) was similar to that in the control strain at 319 nmol H₂. Possible explanations for the contribution of the increased cellular energy reserves to the enhanced hydrogen fermentation observed are discussed based on the viewpoint of metabolic engineering strategy.

• Journal of Animal Science and Technology
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• v.48 no.3
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• pp.375-382
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• 2006

This study was conducted to investigate the effects of dietary herbal plant mixture on growth performance, blood immunological parameters, fecal VFA and NH3-N concentrations in growing pigs. The dietary treatments were 1) NC (negative control; antibiotics-free diet), 2) PC (positive control; NC diet added 0.16% antibiotic), 3) NCK0.2 (NC diet added 0.2% herbal plant mixture (koppuul??)) and 4) PCK0.1 (PC diet added 0.1% herbal plant mixture (koppuul??)). Eighty crossbred (Landrace×Yorkshire×Duroc) pigs (16.35±0.05kg average initial body weight) were used for 42 days. The pigs were assigned to the treatments according to body weight and each treatment had 5 replicates of 4 pigs per pen in a randomized complete block design. During the whole experimental period, PCK0.1 and PC treatments had significantly higher ADG than NC treatment (P<0.05). Gain/feed of pigs fed PC diet was higher than that of pigs fed NC diet (P<0.05). For blood immunological parameters investigations, white blood cells (WBC) counts and IgG level increased in the pigs fed PC, NCK0.2 and PCK0.1 diets compared to pigs fed NC diet. In addition, higher (P<0.05) serum lymphocyte concentration was found in PCK0.1 treatment compared to NC treatment. NH3-N concentration in pigs fed NCK0.2% diet was lower than that in pigs fed PC and NC diets. There were no significant differences in DM and N digestibilities among the treatments. In conclusion, the results suggested that the dietary additions of herbal plant mixture or antibiotics increase ADG, the concentrations of WBC counts and IgG, lymphocyte, while decrease NH3-N concentration in feces.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.2
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• pp.95-99
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• 2002

A pckA gene encoding phosphoenolpyruvate carboxykinase (PEPCK) was cloned and sequenced from the succinic acid producing bacterium Mannheimia succiniciproducens MBEL55E. The gene encoded a 538 residue polypeptide with a calculated molecular mass of 58.8 kDa and a calculated pI of 5.03. The deduced amino acid sequence of the M. succiniciprodutens MBEL55E PEPCK was similar to those of all known ATP-dependent PEPCKS.

• Journal of Life Science
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• v.20 no.2
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• pp.213-218
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• 2010

In the present study, we investigated anti-proliferative activities of capsaicin and gene expression changes in response to capsaicin treatment in human colorectal HCT116 cells. The results showed that capsaicin decreased cell viabilities in a dose dependent manner and induced global gene expression changes. We found that 103 genes were up-regulated more than twofold, whereas 153 genes were down-regulated more than twofold by $100\;{\mu}M$ capsaicin treatment. Among the up-regulated genes, we selected 4 genes (NAG-1, DDIT3, GADD45A and PCK2) and performed RT-PCR to confirm the microarray data. We found that $100\;{\mu}M$ of capsaicin increased tumor suppressor p53 gene expression. In addition, the results showed that NAG-1, DDIT3 and GADD45A expressions were not dependent on p53 presence, whereas PCK2 expression. The results of this study may help to increase our understandings of the molecular mechanism of anti-proliferative activity mediated by capsaicin in human colorectal cancer cells.

• 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 KACE
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• 2018.01a
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• pp.21-23
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• 2018

테크놀로지의 중요성이 증가함에 따라 다양한 영역에 테크놀로지가 활용되고 있다. 교육에서도 효과적인 학습을 촉진하기 위하여 테크놀로지를 도입하고 있다. 하지만 테크놀로지에 대한 교사의 지식 부족으로 인하여 맹목적인 테크놀로지 활용이 이루어지고 있다. 이러한 문제를 해결하기 위하여 TPACK 연구가 활발하게 진행되고 있으며, 김성원과 이영준(2017)은 프로그래밍을 도입한 TPACK-P 교육 프로그램을 개발하였다. TPACK-P 교육 프로그램은 예비 교사의 Technological Pedagogical Knowledge (TPK), Pedagogical Content Knowledge (PCK), Technological Pedagogical Content Knowledge (TPACK) 발달에는 효과적이었지만, Technological Content Knowledge (TCK)에는 영향을 주지 않았다. 본 연구에서는 이러한 문제를 해결하기 위하여 프로그래밍 기반 수업 사례 탐색 및 분석을 보완한 TPACK-P 교육 프로그램을 개선하였다. 개선한 TPACK-P 교육 프로그램이 예비 교사의 TPACK에 미치는 영향을 살펴보기 위하여, K 대학에 다니고 있는 예비 교사 20명을 대상으로 개선한 TPACK-P 교육 프로그램을 적용하였다. 예비 교사의 TPACK 변화를 살펴보기 위하여 박기철과 강성주(2014)의 TPACK 검사 도구를 사용하였다. 이러한 실험을 통하여 TPACK-P 교육 프로그램은 예비 교사의 TPACK 향상에 효과적인 것을 확인할 수 있었다. 또한, TPACK의 모든 세부 영역의 발달에 효과적인 것을 확인할 수 있었다. 본 연구에서는 단일 집단을 대상으로 개선한 교육 프로그램을 적용하였다. 향후 연구에서는 대조군을 설정하고, TPACK-P 교육 프로그램이 예비교사의 TPACK에 미치는 영향을 비교 분석하여야 한다.