• BMB Reports
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• v.38 no.2
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• pp.248-252
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• 2005

Dihydrolipoamide dehydrogenase (E3) catalyzes the reoxidation of dihydrolipoyl moiety of the acyltransferase components of three $\alpha$-keto acid dehydrogenase complexes and of the hydrogen-carrier protein of the glycine cleavage system. His-457 of Pseudomonas putida E3 is suggested to interact with the hydroxyl group of Tyr-18 of the other subunit and with Glu-446, a component in the last helical structure. To examine the importance of the suggested interactions in human E3 function, the corresponding residue of human E3, Asn-473, was substituted to Leu using site-directed mutagenesis. The E3 mutant was expressed in Escherichia coli and highly purified using an affinity column. Its E3 activity was decreased about 37-fold, indicating that Asn-473 residue was important to the efficient catalytic function of human E3. Its slightly altered spectroscopic properties implied that small conformational changes could occur in the E3 mutant.

• Interaction and multiscale mechanics
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• v.1 no.4
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• pp.437-448
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• 2008

This paper examined the stability of high-dense dislocation substructures (HDDSs) associated with martensite laths in High Cr steels supposed to be used for FBR, based on a series of dislocation dynamics (DD) simulations. The DD simulations considered interactions of dislocations with impurity atoms and precipitates which substantially stabilize the structure. For simulating the dissociation processes, a point defect model is developed and implemented into a discrete DD code. Wall structure composed of high dense dislocations with and without small precipitates were artificially constructed in a simulation cell, and the stability/instability conditions of the walls were systematically investigated in the light of experimentally observed coarsening behavior of the precipitates, i.e., stress dependency of the coarsening rate and the effect of external stress. The effect of stress-dependent coarsening of the precipitates together with application of external stress on the subsequent behavior of initially stabilized dislocation structures was examined.

• Bulletin of the Korean Chemical Society
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• v.21 no.12
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• pp.1207-1212
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• 2000

The free energy simulation technique is used to evaluate the relative binding affinity of a set of hydroxyethylene isostere inhibitors of the HIV-1 protease. The binding reactions and an alchemical mutation construct the thermodynamic cycle, which reduces the free energy difference of the binding interactions into that of the alchemical processes. In the alchemical process, a methyl group is mutated into a hydrogen atom. Albeit the change is a small perturbation to the inhibitor-protease complex, it results in 25 fold difference in the binding constants. The simulation reproduces the experimentally measured binding affinities within 2% of the free energy difference. The protonation state of the catalytic aspartic acid residues is also investigated through the free energy simulations.

• Research in Mathematical Education
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• v.26 no.3
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• pp.127-146
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• 2023

Statistical thinking has a broad definition but focuses on the context of regression modelling in the present study. To foster students' statistical thinking within the context, teaching should no longer be seen as transfer of knowledge from teacher to students but as a process of engaging with learning activities in which they develop ownership of knowledge. This study aims at collaborative learning contexts; students were divided into small groups in order to increase opportunities for peer collaboration. Each group of students was asked to do a regression project after class. Through doing the project, they learnt to organize and connect previously accrued piecemeal statistical knowledge in an integrated manner. They could also clarify misunderstandings and solve problems through verbal exchanges among themselves. They gave a clear and lucid account of the model they had built and showed collaborative interactions when presenting their projects in front of class. A survey was conducted to solicit their feedback on how peer collaboration would facilitate learning of statistics. Almost all students found their interaction with their peers productive; they focused on the development of statistical thinking with concerted effort.

• The Journal of Korean Obstetrics and Gynecology
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• v.23 no.2
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• pp.71-84
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• 2010

Purpose: In the theory of traditional medicine, Glenditsia spina(GS) can resolve carbuncle, relive swelling, dispel wind and destroy parasites. This study was designed to investigate the effects of GS on gene expression of ovarian tissue in polycystic ovary syndrome(PCOS) rats. Methods: In this experiment, female rats injected with a single dose of 2 mg estradiol valerate(EV) and GS was given for 5 weeks. The genetic profile for the effects on ovarian tissue in PCOS rats was measured using microarray technique, and the functional analysis on these genes was conducted. Results: 985 genes were increased in control and restored to normal level in GS group. (B), 733 genes were decreased in control group and restored to normal level in GS group. (F). Metabolic pathways related in B group genes were Graft-versus-host disease, Allograft rejection, Autoimmune thyroid disease, Cytokine-cytokine receptor interaction, Small cell lung cancer, Type I diabetes mellitus. Metabolic pathways related in F group genes were Antigen processing and present, Adipocytokine signalling pathway, Focal adhesion, ECM-receptor interaction, Pancreatic cancer, Notch signalling pathway, Tight junction. The network of total protein interactions was measured using cytoscape program, and some key molecules, such as c-Fos, c-Myc, ABL1 related in B group, MAPK8, RASA1, CALR related in F group that can be used for elucidation of therapeutical mechanism of medicine in future were identified. Conclusion: These results suggest possibility of GS as anti-cancer and anti-hyperplasia drug in PCOS. In addition, the present author also suggests that related mechanisms are involved in suppression of proto-oncogene such as c-Fos, c-Myc and ABL1, and in regulation of cell cycle such as RASA1.

• Journal of The Korean Association For Science Education
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• v.19 no.1
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• pp.137-145
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• 1999

This study investigated the influences of the cooperative and the individualistic learning strategies on the academic achievement and the attitudes toward science instruction and science by the level of achievement. These two learning strategies endowed students with the responsibility of learning and emphasized student-centered learning which included higher order thinking activities. Cooperative learning group students studied the tasks through small group discussion, and individualistic learning group students solved the same ones individually. In the traditional group. teacher-centered expository lesson was used. The subjects of this study were 7th graders of coed middle school, and were taught about separation of mixture for 10 class periods. Two-way ANCOVA results revealed that the test scores of academic achievement for cooperative learning group were significantly higher than those of individualistic and traditional learning groups. The attitudes toward science instruction and science were also more positive in cooperative learning group than the others. No interactions between the treatment and the level of previous achievement indicated that the cooperative learning strategy was effective regardless of the level of achievement.

• Journal of The Korean Association For Science Education
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• v.35 no.3
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• pp.419-429
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• 2015

In this study, we explored students' epistemological framing during scientific argumentation and how interactions among group members influenced group argumentation. Twenty-one gifted science students divided into groups of three or four participated in this study. Students' discussions related to data interpretation concerning the rate of photosynthesis were analyzed. Students' activities were videotaped in groups so the discourse could be transcribed and students' behavioral cues analyzed. Students' epistemological framing has been identified through analysis of their speech and behavioral responses to the anomalous data from the inquiry process. Subsequently, their sources of warrant and group argumentation levels were explored. We found out that group members framed the inquiry in two ways: "understanding phenomena" and "classroom game." Group members whose framing was "understanding phenomena" required other members to justify the anomalous data by examining its validity and reliability, which conclusively demonstrated a high level of argumentation. On the other hand, when group members used "classroom game" to frame their argumentation, they did not recognize the necessity of explaining the anomalous data; rather, these students used simple empirical justification to explain the data, reflecting a low level of argumentation. When students using different epistemological framing disagreed over interpretations of anomalous data throughout the discussion, clashes ensued that resulted in emotional conflict and a lack of discussion. Students' framing shifts were observed during the discussion on which group leaders seemed to have a huge influence. This study lays the foundation for future work on establishing productive framing to prompt scientific argumentation in science classrooms.

• Journal of The Korean Association For Science Education
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• v.26 no.2
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• pp.212-221
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• 2006

The purposes of this study were to examine the characteristics of teacher help in small group Thinking Science(TS) activities and analyze the way students respond to teacher help. For this study, twenty-four 5th grade and twenty-four 7th grade students were selected, to undertake TS activities. Out of the 8 activities students participated in, the verbal interactions in activity 4 and 6, by students in four small groups, which incorporated relatively active argumentation was analyzed. Students' cognitive level was identified through a science reasoning task and the students were grouped heterogeneously according to their cognitive level. This study showed that teachers predominately used simple confirmation questions in preference to metacognitive question. Also, teacher help varied according to one's personal traits, work experience and degree of activity recognition. It was discovered that when the teacher provided student appropriate metacognitive questions and sufficient feedback, students actively engaged in argumentation. On the other hand, when the teacher asked simple confirmation questions and interfered in the activity, students did not participate in argumentation actively.

• Journal of Gifted/Talented Education
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• v.20 no.1
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• pp.107-130
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• 2010

The purpose of this study is to investigate the characteristics that indicate scientifically gifted students by analyzing the verbal interactions in developmental biology inquiry-experimental classes. The subjects were 20 first-grade middle school students who were participating in SNU Science Gifted Education Center. In these experimental classes which were developed based on the CPS Model, we conducted a total of four experimental sessions of small group discussions, and the students' verbal interactions were both taped and video recorded, and observed. From the transcriptions, the patterns of question-answer and the characteristics of scientifically gifted students were analyzed. In the case of question-answer patterns, thinking questions appeared 3~6 times more frequently than the standard information questions. Especially, the case of experimental class I showed 40% more thinking questions as well as standard information questions that the other 3 classes. Through the results of analysing verbal interactions, we were able to find more detailed aspects to creativity that were not identifiable in paper-pencil examinations, as well as affective characteristics such as task commitment and leadership. We believe our findings upon inquiry will be of substantial significance in substituting for the paper-pencil examination in distinguishing and selecting scientifically gifted students.

• Journal of The Korean Association For Science Education
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• v.38 no.1
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• pp.69-85
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• 2018

The purpose of this study is to explore teachers' responsive moves that affect students' argumentation practices, and to propose responsive teaching strategies in argumentation-based science classroom. Two teachers, who have not implemented argumentation in their classes, and 57 students, participated in this study. We recorded and transcribed their classes and interviews for the analysis. According to grounded theory approach, we categorized the teachers' responsive moves as focused on either structural or dialogical aspects of argumentation, and qualitatively analyzed their responsive teaching practices in classes. We discovered that the teachers mostly responded to structural rather than dialogical aspects of argumentation, particularly during the students' small-group discussions. This was mainly due to their instructional goals, which focused on the structural aspect of argumentation, and the limited time available for supporting small-groups. Regarding the structural aspects, those responsive moves that explored the students' thinking or facilitated their reasoning helped them to share their thinking and justify their arguments further with recognition of learning goals in the argumentation activities. Regarding the dialogical aspects, which were seen mostly in whole-class discussions, the moves that underlined similarities and differences between arguments, facilitated the sharing of a small-group's arguments with the entire class, or asked a specific student to evaluate the arguments were notable. These moves supported clarification of various small-groups' arguments, which led to reconstruction of coherent argument through evaluation and rebuttal of these arguments, consequentially facilitating dialogical interactions. Based on these results, we proposed responsive teaching strategies in an argumentation-based science classroom.