• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.11-20
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• 2024

In the recent era of NewSpace, unlike high-reliability satellites of the past, low-reliability satellites are being developed and mass-produced at a lower cost to launch constellations satellites. To achieve cost-effective cluster satellite development, satellite users and developers need to assess the feasibility of maintaining mission performance over the expected lifespan when cluster satellites are launched. Plans for replacements due to random failures should also be established to maintain performance. This study proposed a method for assessing system reliability and availability to maintain mission performance and establish replacement strategies for Earth observation constellation satellites. In this study, a constellation reliability and availability model considering mission performance required for a satellite constellation, situations of satellite backup, and additional ground backups was established. The reliability model was structured based on the concept of a k-out-of-n system and the availability model used a Markov chain model. Based on the proposed reliability model, the minimum number of satellites required to meet mission requirements was defined and satellites needed in orbit during the required mission period to satisfy mission reliability were calculated. This research also analyzed the number of spare satellites in orbit and on the ground required to meet the desired availability during required service period through availability analysis.

• Information Systems Review
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• v.24 no.1
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• pp.21-37
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• 2022

Drug repositioning, one of the methods of developing new drugs, is a useful way to discover new indications by allowing drugs that have already been approved for use in people to be used for other purposes. Recently, with the development of machine learning technology, the case of analyzing vast amounts of biological information and using it to develop new drugs is increasing. The use of machine learning technology to drug repositioning will help quickly find effective treatments. Currently, the world is having a difficult time due to a new disease caused by coronavirus (COVID-19), a severe acute respiratory syndrome. Drug repositioning that repurposes drugsthat have already been clinically approved could be an alternative to therapeutics to treat COVID-19 patients. This study intends to examine research trends in the field of drug repositioning using machine learning techniques. In Pub Med, a total of 4,821 papers were collected with the keyword 'Drug Repositioning'using the web scraping technique. After data preprocessing, frequency analysis, LDA-based topic modeling, random forest classification analysis, and prediction performance evaluation were performed on 4,419 papers. Associated words were analyzed based on the Word2vec model, and after reducing the PCA dimension, K-Means clustered to generate labels, and then the structured organization of the literature was visualized using the t-SNE algorithm. Hierarchical clustering was applied to the LDA results and visualized as a heat map. This study identified the research topics related to drug repositioning, and presented a method to derive and visualize meaningful topics from a large amount of literature using a machine learning algorithm. It is expected that it will help to be used as basic data for establishing research or development strategies in the field of drug repositioning in the future.

• Journal of Industrial Convergence
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• v.22 no.4
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• pp.57-64
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• 2024

This study was to confirm the effect of emotional intelligence on organizational commitment of general hospital nurses and the mediating effect of affect. Data was collected using a structured online self-report questionnaire on emotional intelligence, organizational commitment, and both negative and positive affect from 236 nurses working in general hospitals. The data collected were analyzed using descriptive statistics, Pearson's correlation, and a parallel multiple mediation model. This analysis was conducted with IBM SPSS Statistics (Version 27.0) and the PROCESS macro (Model 4). This study's findings revealed that emotional intelligence was significant correlated with positive affect, negative affect, and organizational commitment. Emotional intelligence had a significant direct effect on positive affect (β=.16, p=.015), negative affect (β=-.28, p<.001), and organizational commitment (β=.33, p<.001). Positive affect (β=.20, p=.001) and negative affect (β=-.25, p<.001), had a significant direct effect on organizational commitment. And the mediating effect of positive affect (β=.03, 95% bootstrap CI=0.01~0.07) and negative affect (β=.07, 95% bootstrap CI=0.03~0.12) was also significant. Based on these research results, it will be necessary to research various training programs that can manage emotional intelligence and affect together in developing programs to improve nurses' organizational commitment.

• Journal of The Korean Association For Science Education
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• v.26 no.6
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• pp.691-702
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• 2006

The purposes of the study are to portray Korean beginning secondary science teachers' ways of arranging science content, sense-making strategy, and factors contributing to the tensions between teachers' intentions and actual practice. Six beginning secondary science teachers participated in this study. Science classes taught by the participating teachers were observed and videotaped. Semi-structured interviews were conducted for science teachers participated in this study after science classes were observed. Instructional materials were also collected for each science class. Video- and audio-taped data were transcribed and analyzed using conceptual framework developed by the Michigan State University. The findings of this study produce the following conclusions: (1) beginning teachers' science classes are arranged in ways compatible to traditional school science, (2) frequently used sense-making strategies are procedural display and narrative reasoning, (3) tensions between beginning teachers' intentions and practice arise from two factors such as assessment and differences in educational views with peer teachers, and (4) learning experiences, lack of perceptions and preparations on reform science teaching, and the absence of systematic program for professional development programs for beginning science teachers are major obstacles to reform science teaching for beginning teachers.

• Journal of The Korean Association For Science Education
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• v.27 no.9
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• pp.854-869
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• 2007

In this study, we investigated secondary science teachers' internalization of constructivistic science teaching who participated in a collaborative program between teachers and researchers designed by researchers according to constructivist views. The program consisted of lecture, workshop, and small group activities. New trends in science education and framework for science teaching were introduced during lectures, and understanding about the framework were deepened by analyzing school science classes recorded during workshops. In small group activities, participating teachers and researchers cooperated to design science lesson plans using science teaching frameworks. Five secondary science teachers participated in collaborative workshops. Collaborative programs were video-taped. Semi-structured interviews were conducted before and after workshops. All data recorded were transcribed and analyzed. In the process of internalization, participating teachers attended on different parts. Various and discernable factors such as there own background, beliefs, values, and school context produced tensions with or facilitated internalization of constructivistic science teaching. Teaching experiences and student understanding affected teachers' lesson planning activities. Teachers also showed different understandings on inquiry, application, and model from the framework, and they interpret those concepts in the framework based on their prior understanding. They perceived that too much content should be dealt within relatively limited time. Therefore, they tended to separate science class into two parts when developing science lessons: explaining science content by lecture and science laboratory as a constructivistic activity. The results of the study provide meaningful implications to the constructivist teacher education and professional development.

• Journal of The Korean Association For Science Education
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• v.28 no.6
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• pp.565-578
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• 2008

The purpose of this study is to search for the factors that influence students' understanding of the nature of science through the experience of the cognitive processes of authentic open inquiries. The freshmen of a science high school practiced authentic open inquiries reflecting epistemological characteristics of authentic science. The case study was conducted with four focus students who were successful or unsuccessful at learning the nature of science during the authentic open inquiry activity. Questions that the focus students asked during the inquiries as well as students' answers to pre- and post-VNOS (C type) were analysed, and then elaborated in the semi-structured interview. The findings suggest that open inquiry activities provide the inquiry contexts that help science high school students to understand the nature of science, and that the characteristics of students' cognition influence the understanding of the nature of science. For instance, designing experiments with their own research questions had an influence on the students' understanding about the scientific methods and the diversity of research types, and drawing conclusions from their own data made students experience scientific reasoning. In addition, the experience of collecting anomalous data helped students to understand the role of inferences in generating scientific knowledge and the creative nature of scientific knowledge. In this inquiry context, the reflective thinking that came from proactive discussion among students, made students think about the validity of the designing experiments and interpreting data, and helped them to understand the uncertain nature of reasoning and the diverse nature of scientific methods. Moreover, divergent thinking linked to analogical thinking helped students to understand the creative nature of science.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.333-341
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• 2008

Three embankments are located in the Chunggye Bay, each named as Changpo, Bokkil and Kuil and environmental changes are expected due to freshwater input. To investigate this phenomenon, three sample sites in front of each embankment gate were selected in Nov. 2006(autumn), Feb. 2007(winter), May. 2007(spring) and Aug. 2007(summer). At every point of embankment spot, large cells(micro-size, >$20\;{\mu}m$) of phytoplankton were turned out to be a major cause of algal bloom in Feb. 2007 and nano-size($2-20\;{\mu}m$) phytoplankton became dominant during rainy season. In rainy season, each point of embankment showed low salinity and transparency with higher ammonium and phosphorus concentrations than dry season. However, the number of phytoplankton has decreased and it is expected that freshwater influx has more influence on high turbidity and radical decrease of salinity than nutrient. According to the results of this study, therefore, nutrient could have more influence on growth of phytoplankton in dry season, but high turbidity and radical changes of salinity have more influence in rainy season.

• Journal of The Korean Association For Science Education
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• v.29 no.6
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• pp.593-610
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• 2009

The purpose of this study was to investigate students' views on the value of school science lessons and the aspects of science lessons that appeal to students. For the investigation, semi-structured in-depth interviews with 16 secondary school students were conducted. The results showed that about half of the participants thought that science lessons are important, but not all students have to learn science. And they considered only intrinsic interest and career hopes as critical elements in judging the necessity of science education for all. To appeal to students: first, science lessons should have relevance to students' career hopes, interest, curiosity, abilities, real life, experiences, and test scores. Second, they should acquire students' understanding. Third, they should include more experiments. Finally, they should be related to real life, reflect students' interest and concerns, and link new things with what students already know in terms of contexts and contents. Students thought that science lessons are not suitable for students who don't desire to pursue a science-related career. This suggests that present science curriculum perceived by students doesn't match well with the idea of science education for all. To overcome this problem, students need to be included in the debate about the relevance of science curriculum.

• Journal of The Korean Association For Science Education
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• v.27 no.4
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• pp.346-353
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• 2007

In order to be efficient in teaching, a teacher should understand the current learner's level through diagnostic evaluation. This study has examined the major issues arising from the noble diagnostic assessment tool based on the theory of knowledge space. The knowledge state analysis method is actualizing the theory of knowledge space for practical use. The knowledge state analysis method is very advantageous when a certain group or individual student's knowledge structure is analyzed especially for strong hierarchical subjects such as mathematics, physics, chemistry, etc. Students' knowledge state helps design an efficient teaching plan by referring their hierarchical knowledge structure. The knowledge state analysis method can be enhanced by computer due to fast data processing. In addition, each student's knowledge can be improved effectively through individualistic feedback depending on individualized knowledge structure. In this study, we have developed a diagnostic assessment test for measuring student's learning outcome which is unattainable from the conventional examination. The diagnostic assessment test was administered to middle school students and analyzed by the knowledge state analysis method. The analyzed results show that students' knowledge structure after learning found to be more structured and well-defined than the knowledge structure before the learning.

• Journal of The Korean Association For Science Education
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• v.27 no.9
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• pp.893-906
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• 2007

The purposes of this study are to understand pre-service science teachers' areas of practice concern and reflections on the science classes during student-teaching, and to grasp the factors affecting their concerns and reflections. Four pre-service science teachers participated in this study. Data were collected from four pre-service science teachers' practice journals, instructional materials, and semi-structured individual interviews after their student-teaching. The results are as follows: firstly, the pre-service teachers' concern is focused on the teaching environment and strategies, particularly classroom atmosphere and class management. On the other hand, they pay little attention to science content. Secondly, pre-service teachers' reflections are confined within the limited areas such as classroom management, the proper role as science teachers, or various teaching materials. The level of their reflections is low, mostly concentrated on 'routine' or 'technical' level. Higher levels of reflections, such as 'dialogic' or 'transformative' are not revealed at all. Thirdly, the mentor teachers have the biggest influence upon the concerns and reflections of pre-service teachers during student-teaching.