• Industrial Engineering and Management Systems
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• v.1 no.1
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• pp.1-9
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• 2002

Among the state-space description of discrete vent systems, the max-plus algebra is known as one of the effective approach. This paper proposes a model predictive control (MPC) design method based on the max-plus algebra. Several studies related to these topics have been done so far under the constraints that system parameters are constant. However, in practical systems such as production systems, it is common and sometimes inevitable that system parameters vary by each event. Therefore, it is of worth to design a new MPC controller taking account of adjustable system parameters. In this paper, we formulate system parameters as adjustable ones, and they are solved by a linear programing method. Since MPC determines optimal control input considering future reference signals, the controller can be more robust and the operation cost can be reduced. Finally, the proposed method is applied to a production system with three machines, and the effectiveness of the proposed method is verified through a numerical simulation.

• Journal of Information Science Theory and Practice
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• v.3 no.1
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• pp.66-76
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• 2015

This research uses a new approach to analyze the extent of influence journal papers have on the progress of varied research fields by estimation of subject-based influence on research other than impact factor that relies on citation index. It is initiated with the hypothesis that earlier established citation relations between journal and citing paper, which reveals the research field that contains the highest citation index and hence has received the greatest contribution from a particular journal, would have inconsistent contribution to the research field over the year of journal publication. The target research is primarily 128 journal papers and 4,123 citing papers from Information Systems Research published in the years 2001, 2004, 2007, and 2010. The characteristics of citation history and hallmarks of research field of citing papers were studied and analysis on significant distinction between citing fields based on the year of publication was performed. The analysis results show the order of citation rate to be highest from Computer Science (2,221 cases), Business & Economics (2,191 cases), and Information Science & Library Science (1,901 cases). The citation history of the journal, nonetheless, indicates increase in citation during 2-3 years after the earliest publication till it achieves constant citation. The statistical analysis shows significant variation in citing fields in accordance with the publication year; especially in 2010, journal contribution has increased in the fields of Business & Economics, Operations Research & Management Science, and Health Care Sciences & Services but, however, is reduced in Education & Educational Research and Social Sciences - Other Topics.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.1
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• pp.45-52
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• 2021

The capital structure is one of the hot financial topics among researchers and scholars. Its importance comes from the fact that capital structure is closely related to companies' ability to meet different stakeholders' needs. A suitable capital structure will boost the business and create a competitive advantage in the context of fierce competition. Many companies choose an optimal debt level based on the trade-off between interest and debt costs. This study aimed to test the existence of trade-off theory in capital structure, the case of Vietnam's real estate companies, which are growing very fast recently. Instead of considering constant optimal leverage to test the trade-off model, we take advantage of the dynamic capital structure determined by growth opportunities, profitability, tax incentives, tangibility, liquidity, and firm size. The dynamic panel data regression was estimated by the system Generalized Method of Moment (Sys-GMM). The empirical evidence showed that real estate companies listed in the Vietnamese stock market might change their leverage toward a target capital structure determined by influential factors in a long-term perspective. In particular, the debt-to-asset ratio will change by approximately 14 percent, positively, in response to the difference between the current debt-to-asset ratio and the dynamic target debt-to-asset ratio.

• Journal of Contemporary Eastern Asia
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• v.20 no.1
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• pp.44-72
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• 2021

This study analyses North and South Koreas' coverage as framed by the main Polish press titles from 1989 to 2019. The main method applied is a computational textual analysis of press articles based on frequency, correlations and co-occurrences. The purpose is to map the topics of the examined articles in the context of relations between Poland and the two Koreas in various areas, predominantly political and economic relations. Emphasis is placed on the impact the carmaker Daewoo's investment in Poland in the mid-1990s had on bilateral Polish-South Korean relations. First, the authors argue that Korean issues in the Polish press, mainly in the second half of the 1990s, particularly concerned economic affairs. Secondly, they argue that after Poland's accession to the European Union in 2004, the country's interest in the two Koreas decreased, and since that time has remained at a more or less constant level. Finally, the authors discuss the outcome of the research in the context of the main developments in Polish-Korean relations, taking into consideration the results of a Polish public opinion survey presenting the international linkages between national public opinion and foreign policy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.11
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• pp.2966-2986
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• 2023

Climate change is a constant threat to human life, and it is important to understand the public perception of this issue. Previous studies examining climate change have been based on limited survey data. In this study, the authors used big data such as news articles and social media data, within which the authors selected specific keywords related to climate change. Using these natural language data, topic modeling was performed for discourse analysis regarding climate change based on various topics. In addition, before applying topic modeling, sentiment analysis was adjusted to discover the differences between discourses on climate change. Through this approach, discourses of positive and negative tendencies were classified. As a result, it was possible to identify the tendency of each document by extracting key words for the classified discourse. This study aims to prove that topic modeling is a useful methodology for exploring discourse on platforms with big data. Moreover, the reliability of the study was increased by performing topic modeling in consideration of objective indicators (i.e., coherence score, perplexity). Theoretically, based on the social amplification of risk framework (SARF), this study demonstrates that the diffusion of the agenda of climate change in public news media leads to personal anxiety and fear on social media.

• Journal of the Korea Institute of Building Construction
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• v.14 no.4
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• pp.292-300
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• 2014

The construction progress control is very important because there are many unexpected factors affecting time schedule delay and cost overruns. A complicated measure including item quantity and inherent time and costs is used to monitor the progress. Another element to be considered is a productivity, which is cost effectiveness because productivity is primarily measured by the costs. Productivity is stated as constant in-place value divided by inputs such as worker-hour. The main purpose of this paper is to analyze the productivity of structural formwork using a 3D BIM. In order to achieve the research objective, an integrated model of a BIM with a daily foreman's report is developed. The quantities being extracted from a 3D model and information are integrated with manpower utilized. The developed model is applied to a case project to measure and analyze the productivity in terms of individual building and work crew team. The results are discussed and further research topics will be addressed.

• Journal of Korean Academy of Nursing
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• v.30 no.4
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• pp.1018-1034
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• 2000

The purpose of this study was to construct model of sexual adjustment in people with spinal cord injury and to determine factors that relate to sexual adjustment using methodological triangulation. A total of 134 persons who were registered members of spinal cord injury organization and admitted rehabilitation unit in the hospital were included in the study. Participants answered questionnaire concerning importance of life events, sexual concern, sexual adjustment. Qualitative data were collected through semi-structured indepth interviews from 10 individuals with spinal cord injury who were previously included in the quantitative study. Constant compatative method was used to analyze the data. The results were as follows : 1) With respect to eleven other areas of life, sex life ranked the sixth and economic status ranked the highest in terms of importance. However social life ranked the lowest among the 11areas. 2) Among seven topics related to sexuality were methods and techniques to achieve sexual satisfaction, and helping a partner cope emotionally with limitation on sexual dysfunction was the second greastest. 3) The mean score for sexual adjustment was 19.47 which can be considered. 4) A process on how individuals with spinal cord injury adjust to their changed sexual life immerged from the qualitative data. It includs 4 stages: 'stage of loss' 'stage of endeavoring' 'stage of effort' and 'stage of adjustment'. Categories showing context for the action/interaction strategies were 'steadiness' and 'rediscovery as a sexual being'. There were three factors which may stimulate the adjustment process while the others may interrupt it. Those factors included personal matters, family matters and social matters. The individuals may follow each stage step by step but may go back to the previous step depending on the outcomes of their adjustment. 5) There were three factors which may stimulate the adjustment process while the others may interrupt it. Those factors included personal matters, family matters and social matters.

• The Mathematical Education
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• v.34 no.1
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• pp.17-63
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• 1995

The exploration of Mathematics-learningmodel on the basis of Cognitive development The purpose of this paper is to sequenctialize Mathematics-learning contents, and to explore teaching-learning model for mathematics, with on the basis of the theory of cognitive development and the period of condservation formation for children. The Specific topics are as follows: (1) Systemizing those theories of cognitive development which are related to Mathematics - learning for children. (2) Organizing a sequence of Mathematics - learning, on the basis of experimental research for the period of conservation formation for children. (3) Comparing the effects of 4 types of teaching - learning model, on the basis of inference activity and operational learning principle. $\circled1$ Induction-operation(IO) $\circled2$ Induction-explanation(IE) $\circled3$ Deduction-operation(DO) $\circled4$ Deduction-explanation(DE) The results of the subjects are as follows: (1) Cognitive development theory and Mathe-matics education. $\circled1$ Congnitive development can be achieved by constant space and Mathematics know-ledge is obtained by the interaction of experience and reason. $\circled2$ The stages of congnitive development for children form a hierarchical system, its function has a continuity and acts orderly. Therefore we need to apply cognitive development for children to teach mathematics systematically and orderly. (2) Sequence of mathematical concepts. $\circled1$ The learning effect of mathematical concepts occurs when this coincides with the period of conservation formation for children. $\circled2$ Mathematics Curriculum of Elementary Schools in Korea matches with the experimental research about the period of Piaget's conservation formation. (3) Exploration of a teaching-learning model for mathematics. $\circled1$ Mathematics learning is to be centered on learning by experience such as observation, operation, experiment and actual measurement. $\circled2$ Mathematical learning has better results in from inductional inference rather than deductional inference, and from operational inference rather than explanatory inference.

• The Journal of the Korea Contents Association
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• v.14 no.8
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• pp.528-541
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• 2014

The purpose of this study is to analyze Yun Chi-ho's English Diary both quantitatively and qualitatively. A corpus of 574 diary texts is created from his first and last years in an English speaking environment, and analyzed by two language analysis programs, RANGE and Coh-Metrix. His later diaries have more words in total, and longer average sentence length than his earlier diaries. Also, the Coh-Metrix indices in syntactic complexity and referential cohesion are higher in his later diaries. A qualitative analysis of 57 diary texts shows some improvement in his use of language forms. The most frequent topics of his journals are Christianity, everyday life, politics of Korea and his English studies. His constant effort to keep his journal and correspondence with foreigners, almost all in English, is estimated as one of the key factors for his successful English acquisition. Educational implications for EFL writing courses are discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.354-372
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• 2020

This study analyzed how North Korean defectors recognized and overcame conflict in the South Korean job culture during the course of entering and settling into South Korea, and the association between their old career and adaptation within their new careers. The study selected 13 employed participants who entered South Korea more than five years ago and experienced working. Interviews were conducted over the course of five years. The topics were analyzed after performing interviews 60 to 120 minutes long by recording and transcribing the recordings and using semi-structured questionnaires for the 13 people. The results reflected the job environment in North Korea, their career background, factors for a successful new life, their constant efforts for employment, the difficult adaption to South Korean life, pursuing job stability, accepting South Korean culture, and career compromises. The results of this study are as follows. First, they undergo difficulty in the course of selecting jobs due to the converted environment from passivity to autonomy. Second, they cannot use their previous job history and they complained about prejudice and the lack of job information. Third, major problems included their lack of adaptability, stress, and loss of economic power. The study suggests that these North Korean defectors undergo an integrated course of cultural learning. Fourth, they were hardly able to adapt. Fifth, they tried to overcome conflicts of job culture according to their personal characteristics.