• Nuclear Engineering and Technology
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• v.27 no.2
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• pp.203-215
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• 1995

A continued operation of RCPs during a certain small break LOCA may increase unnecessary inventory loss from the RCS causing a severe core uncovery which might lead to a fuel failure. After TMI-2 accident, the CEOG developed RCP trip strategy called “Trip-Two/Leave-Two” (T2/L2) in response to NRC requests and incorporated it in the generic EPG for CE plants. The T2/L2 RCP trip strategy consists of tripping the first two RCPs on low RCS pressure and then tripping the remaining two RCPs if a LOCA has occurred. This analysis determines the RCP trip setpoint and demonstrates the safe operational aspects of RCP trip strategy during a small break LOCA for YGN 3&4. The trip setpoint of the first too RCPs for YGN 3&4 is calculated to be 1775 psia in pressurizer pressure based on the limiting small break LOCA with 0.15 ft$^2$ break size in the hot leg. The analysis results show that YGN 3&4 can maintain the core coolability even if the operator fails to trip the second too RCPs or trips at worst time. Also, the YGN 3&4 RCP trip strategy demonstrates that both the 10 CFR 50.46 requirements on PCT and the ANSI standards 58.8 requirements on operator action time can be satisfied with enough margin. Therefore, it is concluded that the T2/L2 RCP trip strategy with a trip setpoint of 1775 psia for YGN 3&4 can provide improved operator guidance for the RCP operation during accidents.

• Journal of Chest Surgery
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• v.37 no.6
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• pp.482-491
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• 2004

Background: The xenogenic or allogenic valves after in Vitro repopulation with autologous cells or in vivo repo-pulation after acellularization treatment to remove the antigenicity could used as an alternative to synthetic polymer scaffold. In the present study, we evaluated the process of repopulation by recipient cell to the acellu-larized xenograft treated with NaCl-SDS solution and grafted in the right ventricular outflow tract. Material and Method: Porcine pulmonary valved conduit were treated with. NaCl-SDS solution to make the grafts acellularized and implanted in the right ventricular outflow tract of the goats under cardiopulmonary bypass. After evaluating the functions of pulmonary valves by echocardiography, goats were sacrificed at 1 week, 1 month, 3 months, 6 months, and 12 months after implantation, respectively. After retrieving the implanted valved conduits, histopathologic examination with Hematoxylin-Eosin, Masson' trichrome staining and immunohistochemical staining was performed. Result: Among the six goats, which had been implanted with acellularized pulmonary valved conduits, five survived the expected time period. Echocardiographic examinations for pulmonary valves revealed good function except mild regurgitation and stenosis. Microscopic analysis of the leaflets showed progressive cellular in-growth, composed of fibroblasts, myofibroblasts, and endothelial cells, into the acellularized leaflets over time. Severe inflammatory respon-se was detected in early phase, though it gradually decreased afterwards. The extracellular matrices were regenerated by repopulated cells on the recellularized portion of the acellularized leaflet. Conclusion: The acellularized xenogenic pulmonary valved conuits were repopulated with fibroblasts, myofibroblasts, and endothelial cells of the recipient and extracellullar matrices were regenerated by repopulted cells 12 months after the implantation. The functional integrity of pulmonary valves was well preserved. This study showed that the acellularized porcine xenogenic valved conduits could be used as an ideal valve prosthesis with long term durability.

• Korean Journal of Social Welfare Studies
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• v.49 no.1
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• pp.51-83
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• 2018

This study examines whether the widening gap between income groups is worsening in the distribution of time use, similar to the worsening of income distribution after the IMF. To do this, we conducted multilevel analysis (HLM) on six countries including France, the Netherlands, Spain, the United Kingdom, the United States and Korea. The results of the analysis are as follows. First, in all countries, low income groups have a longer paid working time and shorter leisure time. Second, the low income groups in Korea have the longest paid work time and the shortest leisure time, the lowest level of work-leisure balance, and this aspect has not recovered since the IMF. Third, as the result of multilevel analysis, the lower the household income, the more time paid labor increased and the work-leisure balance decreased. Fourth, while average annual working hours increase paid working time, the expansion of family policy expenditure, redistribution policy and income maintenance policy has reduced it. Fifth, the annual average working hours decreased the work-leisure balance, but the family policy expenditure, the redistribution policy and the income guarantee policy increased the work-leisure balance. The significance of this study is that after the IMF, not only the income distribution but also the inequality among the income class in time use has deepened. Based on the results of the research this study suggests the reinforcement of labor time regulation, the activation of parental leave system, the realization of the income replacement rate, the expansion of the policy related to income redistribution, and the complementary development of the income guarantee and the time guarantee policy as the policy intervention strategy that restructures time.

• Journal of Elementary Mathematics Education in Korea
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• v.15 no.1
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• pp.19-38
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• 2011

The purpose of this study was to analyze the responses and the behavioral characteristics between mathematically promising students and normal students in solving open-ended problems. For this study, 55 mathematically promising students were selected from the Science Education Institute for the Gifted at Seoul National University of Education as well as 100 normal students from three 6th grade classes of a regular elementary school. The students were given 50 minutes to complete a written test consisting of five open-ended problems. A post-test interview was also conducted and added to the results of the written test. The conclusions of this study were summarized as follows: First, analysis and grouping problems are the most suitable in an open-ended problem study to stimulate the creativity of mathematically promising students. Second, open-ended problems are helpful for mathematically promising students' generative learning. The mathematically promising students had a tendency to find a variety of creative methods when solving open-ended problems. Third, mathematically promising students need to improve their ability to make-up new conditions and change the conditions to solve the problems. Fourth, various topics and subjects can be integrated into the classes for mathematically promising students. Fifth, the quality of students' former education and its effect on their ability to solve open-ended problems must be taken into consideration. Finally, a creative thinking class can be introduce to the general class. A number of normal students had creativity score similar to those of the mathematically promising students, suggesting that the introduction of a more challenging mathematics curriculum similar to that of the mathematically promising students into the general curriculum may be needed and possible.

• Education of Primary School Mathematics
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• v.21 no.3
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• pp.273-287
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• 2018

The purpose of this study was to analyze changing aspect of teacher and student's value in mathematics instruction. For this purpose, teacher and student's value are analyzed through value questionnaire by four times. The results of this study revealed that although value are individual's deep decision mechanism, it could change considerably by the time. Teacher wasn't compel students to follow her value. Rather, teacher was modified instruction goal to reflect students thinking what is important in mathematics lesson. First, in case of mathematical value, rationalism, objectism, mystery were convergent each other. And control was almost unchanged and openness has been onwards and upwards. Second, in case of mathematics educational value, understanding, pleasure, terminology and application were convergent each other. However achievement was almost unchanged. Also, to teach effectively, teacher using several kinds strategy while negotiate with student's value continuously. On the basis of these results, this paper includes several implications for the future study about values in mathematics which could be the critical factor in student centered instruction.

• Journal of Digital Convergence
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• v.16 no.9
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• pp.329-338
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• 2018

The purpose of this longitudinal study was to investigate confidence in core basic nursing skill each period of clinical practicum and discover the changes, depending on characteristics of periods. The data was collected for 94 nursing students attending a university located in J-do from Mar. 9 to Dec. 16 2016 for 4 times in total. For data analysis, the frequency analysis, descriptive statistics and paired t-test were used. The research findings showed that confidence in core basic nursing skill by each period of clinical practicum was lowest before clinical practicum in general but gradually increased depending on lapse of time and experience of clinical practicum. However, it decreased in all items after having first clinical practicum in the $2^{nd}$ semester, compared to after first clinical practicum in the $1^{st}$ semester. In addition, the difference of confidence in core basic nursing skill between clinical practicum periods was higher after the first clinical practicum in the $1^{st}$ semester and after clinical practicum at the end of school year, compared to before clinical practicum and after the first clinical practicum in the $2^{nd}$ semester respectively. Therefore, this study suggested that it's necessary to have efficient and systematic clinical practicum education strategy, reflecting the characteristics of periods in clinical practicum in order to improve the confidence in core basic nursing skill of nursing students.

• Journal of Convergence for Information Technology
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• v.8 no.3
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• pp.145-152
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• 2018

This study aims to investigate the effects of literary texts as a teaching tool to enhance college students' English communicative competence both in linguistic aspects and affective ones. The control group used only the course book as study material, whereas the target group read four short stories along with it and engaged in a series of follow-up tasks. To measure their English competence, the researcher had both groups take a pre-test and a post-test, compared the results, and analyzed the data using SPSS. The study indicates that though the target students' post-test scores increased, the result failed in reaching a significant level. Nevertheless, reading and discussing literature facilitated the target students' affective aspects of communication. This article points out some other limitations of utilizing literary texts in language teaching and suggests the need for further research to deal with the issues.

• Information Systems Review
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• v.25 no.3
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• pp.27-41
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• 2023

Unlike the previous works focusing on the state-of-the-art methodologies to improve the performance of machine learning models, this study improves the 'quality' of training data used in machine learning. We propose a method to enhance the quality of training data through the processing of 'local grammar,' frequently used in corpus analysis. We collected a vast amount of unstructured corporate review text data posted by employees working in the top 100 companies in Korea. After improving the data quality using the local grammar process, we confirmed that the classification model with local grammar outperformed the model without it in terms of classification performance. We defined five factors of work engagement as classification categories, and analyzed how the pattern of reviews changed before and after the COVID-19 pandemic. Through this study, we provide evidence that shows the value of the local grammar-based automatic identification and classification of employee experiences, and offer some clues for significant organizational cultural phenomena.

• Journal of The Korean Association For Science Education
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• v.34 no.5
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• pp.449-457
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• 2014

Recent studies have shown that teachers should have be aware of and understand students' misconceptions, which is one of the major components of PCK. However, teachers often have difficulties in understanding misconceptions and in applying appropriate instructional strategies to change misconceptions. Thus, we designed a method course for pre-service teachers (PSTs) adapting the concept of "teacher as researcher". In the course, PSTs conducted research to investigate students' misconceptions in physics. Twenty-five female PSTs participated in the study. They went through the research process including creating question items, administering items to their target populations, collecting and analyzing student responses, and writing a research paper. Data source included individual interviews with the PSTs, field notes during classroom observation and PSTs' research papers. The results were as follows. First, the PSTs confirmed students' misconceptions and learning difficulties in physics. They experienced discrepancies between their conjecture and research findings. Second, PSTs developed the sophisticated understanding of students' misconceptions and appropriate teaching strategies. Third, the research experience provided the PSTs opportunities to reexamine their physics content knowledge while creating items and explaining scientific concepts. They realized that physics teachers should develop sound understanding of physics concepts for guiding students to have less misconception. Lastly, they realized the necessity of being a teacher as a researcher.

• Korean Journal of Cognitive Science
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• v.20 no.4
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• pp.507-533
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• 2009

This paper examines the time course and processing patterns of filler-gap dependencies in Korean relative clauses, using an eyetracking method. Participants listened to a short story while viewing four pictures of entities mentioned in the story. Each story is followed by an auditorily presented question involving a relative clause (subject relative or dative relative). Participants' eye movements in response to the question were recorded. Results showed that the proportion of looks to the picture corresponding to a filler noun significantly increased at the relative verb affixed with a relativizer, and was largest at the filler where the fixation duration on the filler picture significantly increased. These results suggest that online resolution of the filler-gap dependency only starts at the relative verb marked with a relativiser and is finally completed at the filler position. Accordingly, they partly support the filler-driven parsing strategy for Korean, as for head-initial languages. In addition, the different patterns of eye movements between subject relatives and dative relatives indicate the role of case markers in parsing Korean sentences.