• Journal of the Korean School Mathematics Society
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• v.25 no.3
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• pp.279-306
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• 2022

The purpose of this case study is to get an implication on elementary pre-service teacher education programs by exploring how a pre-service teacher's noticing changes within a learning community. The pre-service teacher participated in a learning community with researchers. Data includes recordings and transcription of actual class and pre- and post discussion in the learning community, the pre-service teacher's reflection essays, field notes, and students' worksheets. Results are as follows. First, the pre-service teacher's attending moved from the result of tasks to students' mathematical thinking. Second, the pre-service teacher's interpretation changed from a lack of diversity and specificity of evidence to diversity and specificity. Third, the pre-service teacher's decision-makings changed from unproductive deciding to productive deciding.

• The Mathematical Education
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• v.54 no.4
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• pp.351-363
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• 2015

In this study, 45 pre-service mathematics teachers were surveyed about how the perception of knowledge through teaching practicum have changed and how the knowledge learned in college and teaching practicum helped to format teachers' knowledge and analyzed survey's result. Pre-service mathematics teachers felt the knowledge for understanding students were needed the most and considered the experiences from teaching practicum were more useful than the knowledge learned from college classes. However, they had low appreciations on connecting knowledge on learned contents with real-life or other subjects and on necessity of knowledge of using various learning tools or mathematical materials in class. Also, they have answered the knowledges from college classes and teaching practicum were useless in those areas. Especially, they pointed out that guidance teachers during teaching practicum were insufficient in instructing. Therefore, we suggest the following two to improve the teaching ability of pre-service mathematics teachers through teaching practicum. First, college and secondary school cooperating programs such as class-observation and student-mentor system connected with local society should be developed. Second, the special re-training program for guidance teachers of teaching practicum is needed.

• The KSFM Journal of Fluid Machinery
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• v.15 no.3
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• pp.57-63
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• 2012

Effects of coolant pre-cooling and fuel pre-heating on the performance of a combined cycle using a F-class gas turbine were investigated. Coolant pre-cooling results in an increase of power output but a decrease in efficiency. Performance variation due to the fuel pre-heating depends on the location of the heat source for the pre-heating in the bottoming cycle (heat recovery steam generator). It was demonstrated that a careful selection of the heat source location would enhance efficiency with a minimal power penalty. The effect of combining the coolant pre-cooling and fuel pre-heating was also investigated. It was found that a favorable combination would yield power augmentation, while efficiency remains close to the reference value.

• Journal of the Korean Society of Earth Science Education
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• v.5 no.3
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• pp.307-315
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• 2012

The purpose of this study was to examine the effects of small inquiry method on space perception ability and creative personality. Testees of this research are 36 elementary pre-service teachers taking an astronomical observation class. Doing inquiry activity after 36 elementary pre-service teachers are classified into 6 Jigsaw small inquiry. Learning activity was split into two groups, expert group and a population. To find out research outcome, pre-test was executed space perception ability test, creative personality test. Analysis of test result was accomplished with statistical package SPSS 18.0 paired t testing hypothesis. The results of this study are as follows. First, 'source of season change' class using Jigsaw small inquiry method has effect on space perception ability improvement. This was interpreted that space perception ability improvement was effective because characteristic of Jigsaw small inquiry is made up of lots of semin Second, 'source of season change' class using Jigsaw small inquiry method has no effect on creative personality. This was interpreted that experiment and discussion activity getting accomplished in a short time has no effect on qualitative characterizing Creative Personality improvement.

• KIPS Transactions on Software and Data Engineering
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• v.9 no.12
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• pp.411-418
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• 2020

In the field of information security, IDS(Intrusion Detection System) is normally classified in two different categories: signature-based IDS and anomaly-based IDS. Many studies in anomaly-based IDS have been conducted that analyze network traffic data generated in cyberspace by machine learning algorithms. In this paper, we studied pre-processing methods to overcome performance degradation problems cashed by rare classes. We experimented classification performance of a Machine Learning algorithm by reconstructing data set based on rare classes and semi rare classes. After reconstructing data into three different sets, wrapper and filter feature selection methods are applied continuously. Each data set is regularized by a quantile scaler. Depp neural network model is used for learning and validation. The evaluation results are compared by true positive values and false negative values. We acquired improved classification performances on all of three data sets.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.145-146
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• 2006

The main objective of this research is to develop a system which will provide a more efficient fuel saying measure for the current marine products industry situation caused by the increased cost of oil. For that function, the developed system has been verified using the medium of blending oil known as the MF 30 class. As a result, MF 30 was confirmed meeting the International Standard for NOx emissions and content of Sulfur. Oil composition and soot level analysis showed that it is acceptable to use MF 30 class in condition of proper engine running operation and pre-refinery treatment.

• Journal of The Korean Association For Science Education
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• v.14 no.2
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• pp.111-122
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• 1994

This study tried to find the effect to the representation patterns of science concepts upon the momentum effect. The previous studies showed that the momentum effect is influenced by students' cognitive levels and the abstractness of test items. The representation patterns of science concepts are divided into 4 different types: quantitative and qualitative, verbal and image. The research method used in this study is time series design. The period is 50 days. The period is divided into "pre-lest", "intervention-test", "post-test". Pre-test period is 5 days and in this period class instruction does not exist. Intervention-lest period is 30 days and in this period class instruction exist. Post-test period is 15 days and in this period class instruction does not exist. The results showed longer momentum effect on the image-qualitative representation pattern than the other representation patterns. Qualitative concepts is formed better than quantitative. Momentum effects is not artifact but the essential characteristics of science study.

• Journal of The Korean Association For Science Education
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• v.14 no.1
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• pp.70-84
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• 1994

This study tried to find the effect to cognitive structure upon the momentum effect. The previous studies showed that the momentum effect is influenced by students' cognitive levels and the abstractness of test items. The cognitive structure is examined by cognitive level and cognitive style. Cognitive levels and cognitive styles are determined by GALT and GEFT respectively. The research method used in this study is time series design. The period is 50 days. The period is divided into "pre-test", "intervention-test", "post-test". Pre-test period is 5 days and in this period class instruction does not exist Intervention-test period is 30 days and in this period class instruction exist Post-test period is 15 days and in this period class instruction does not exist. Field independent students showed longer momentum effect than field dependent students. Formal level students showed less ratio of decrease on post-test than nonformal level students. Momentum effects is not artifact but the essential characteristics of science study.

• Journal of Chest Surgery
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• v.23 no.2
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• pp.236-244
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• 1990

To improve the prognosis of mitral valve replacement surgery, analysis and evaluation of pre and intra operative risk factors will be very much valuable. Author studied 205 cases of mitral valve replacement from Feb 1982 to June 1989 for the risk factors of hospital death. 90 patients were male and 115 were female, and age was from 16 to 59 years, Mitral stenosis dominant lesions were 91 cases and regurgitation 114. Suspected risk factors were NYHA functional class, cardiothoracic ratio, implanted valve type and size, operation time, age and sex, thrombus in left atrium, atrial fibrillation, aortic cross clamping time, left ventricular end diastolic and systolic dimension, nephropathy, hepatopathy and respiratory insufficiency. Statistic analysis was performed by X2 test between survivors and death group. Statistical significances as pre and intraoperative risk factors of hospital death after mitral valve replacement were confirmed in those presence of AF on the EKG, NYHA functional class[>IV], cardiothoracic ratio[>70%], and implanted valve size[>33mm]

• Journal of Ocean Engineering and Technology
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• v.16 no.3
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• pp.59-64
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• 2002

In the present study, we examined the influence of prestrain on creep strength of Class M alloy(STS310S) and Class A(STS310J1TB) alloys containing precipitates. Prestrain was given by prior creep at a higher stress than the following creep stresses. Creep behaviour before and after stress change and creep rate of pre-strained specimens were compared with that of virgin specimens. Pre-straining produced the strain region where the strain rate was lower than that of a virgin specimen both for STS310J1TB and STS310S steels. The reason for this phenomenon was ascribable to the viscous motion of dislocations, the interaction between dislocations and precipitates in a STS310J1TB steel, and the interaction of dislocations with sub-boundaries in a STS310S steen which has the higher dislocation density and smaller subgrain size resulted from pre-straining at higher stress.