• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.267-275
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• 2012

In this study, normal wind load and blast wind load are modeled mathematical. And the periodical torque and bending moments transmitted to the main shaft of wind turbine are investigated. A normal wind model assumed, of which the wind velocity is increased according to the height from ground. The average values and the harmonic terms of the transmitted moments are studied on the wind direction of range $-45^{\circ}{\sim}45^{\circ}$ and the bending moment characteristics are examined, which is regarded as the main source of the misalignment of gear train. In normal wind load case, excitation frequency is 3X (X : Rotor speed). When the wind direction is $+22.5^{\circ}$, the horizontal axis of bending moment occur the 50% of main torque. This result leads to edge contact of gear teeth by shaft elastic deformation. In blast wind load case, excitation frequency are 3X,6X,9X. Additional, in the (+) direction of wind load, relative harmonic percentage is increase.

• Journal of Educational Research in Mathematics
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• v.17 no.3
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• pp.271-293
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• 2007

Mathematics workbook is developed according to the amendment of the 7th national curriculum of mathematics. This study polled 300 national mathematics teachers in the elementary school, middle school, and high school to find out what they think in conjunction with the introduction of mathematics workbook such as needs for mathematics workbook, teachers' recognition about the system of mathematics textbook and workbook which are proper for lesson of achievement level and organization of mathematics workbook before using the mathematics workbook in school. As a results, mathematics teachers want the introduction of workbook because it helps students' self-regulated learning of mathematics and it is material very valuable for teachers to give lessons of achievement level. Also, we suggest the organization and contents of mathematics workbook on the base of our survey. Mathematics workbook has a lot of exercises assessing into the upper, intermediate, lower level in the contents, concepts of mathematics learning. It has the items developed with various problem solving methods and emphasis on performance tests, an essay-type examination and a periodical assessment. It has the problem posing items and the corner that helps students revise their mathematical errors and proposes useful, interesting mathematical activities and the commentary of a correct answer to questions at the tail of the book.

• Journal of Korean Library and Information Science Society
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• v.8
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• pp.127-154
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• 1981

Today's complicated society with a rapid change needs more objective and accurate data for the better managerical decisions and the prospect for the future other than the intuition or subjective experience by men themselves. These data can't be extracted without the analysis of actual data by a n.0, pplying any of mathematical techniques. One of these mathematical techniques, called bibliometrics has been newly developed in the field of library and information science to extract the objective data for the better services through the library operations. The Beadford's Law, one important law in bibliometrics has provided rather scientific and objective basis on the more valid building of library collection within the constraints of budget. The purpose of the study is to investigate the theory of the Bradford's Law, to clarify the possible areas of its a n.0, pplication, and to discern some problems in doing so. The results of the study can be summarized as follows; (1) There is certain difference between the graphical formulation and verbal formulation of Bradford's Law. But this law is very useful for the field of library and information science, owing to the flexibility of the a n.0, pplication of the law in the field. (2) The minimal nucleus can consist of a single periodical only if j, the number of relevant papers in the most productive journals is greater than Z/2. On the other hand, if j is less than or equal to Z/2, then the minimal nucleus will consist of 2 or more periodicals. (3) It is possible to design the most compact selection of scientific periodicals covering any specified percentage P among the total periodicals by using the formulation, log n=Plog N+(1-P)logs, or Nlog N/s=P center dot N log N/s. (4) If there is need to provide all the articles needed by users the given budget, the library can purchase the proper number of journals, by using the formulation, f center dot AN=An+PN (log N/s-logn/s). (5) In the building of the library collection based on the decreasing ratio of use, the library can subscribe to the proper number of journals according to the satisfactory degree of the need, by using the formulation, f=Nu+uNlogN/S-uNlogn/s / nNlogN/s = 1+logN/m /logN/s (6) If the order of valuable journals is decided according to the frequency of being cited, the order can't always represent the value. (7) The evaluation criteria for the journals with high value, but less cited should be made a further study.

• School Mathematics
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• v.5 no.3
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• pp.315-342
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• 2003

The goals of this study are basically to analyze the lectures related to mathematics education in national universities of education and in education training institutes, and ultimately to suggest the collaboration in the lectures related to mathematics education in national universities of education and education training institutes. In order to achieve the above goals, five universities were selected. Summing up these results, we suggest several ways to collaborate the mathematics education lectures in national universities of education and education training institutes. First, the training education in the national university of education has to offer more lectures which deal with the theory related with mathematical education and the fundamental area of mathematics. In addition to this, teaching in contents in terms of the area has to focus on the background knowledge related to the teaching contents. Second, based on the training education, the assigned education training institute has to reflect the periodical and social condition. In addition to this, it has to reflect the real condition around the school environment. With those efforts it has to make new kinds of lectures which concentrate on the recent trend or the understanding of the theory related with mathematical education. In this case, both obligatory and elective courses have to be offered. Third, the education training institute responsible for the staff development program has to open lectures with the contexts of real time teaching activities based on the experiences of the teachers. In this case, one or two particular subjects have to be dealt with in depth and lecturers have to be selected who are suitable for the lectures.

• The Mathematical Education
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• v.61 no.4
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• pp.559-579
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• 2022

Research on lexicon and language provides insights into the interests, values and practices of a community where individuals use the language. The International Classroom Lexicon Project, in which ten countries participated, identified own country's mathematics teaching and learning lexicons by investigating mathematics classroom instruction from teachers' perspectives in a speaking-oriented community. This study, as an extension of the International Classroom Lexicon Project research, investigated pedagogical lexicons used in 「Mathematics and Education」 journals specialized for Korean professional mathematics teachers published by the Korean Society of Teachers of Mathematics. Using the text mining approach, we also traced how these pedegogical lexicons have changed quantitatively over the past 10 years with a diachronic perspective. As a results, several novel terms were found in the writing-oriented community, which were not identified in the speaking-oriented community. In addition, we could discover some pedagogical lexicons have increased statistically significantly and some lexicons appeared(increased) rapidly across years. This implies the teacher community's values and zeitgeist by reflecting these changes in the sociocultural, incidental and social changing (i.e., periodical change) contexts. This study has value as a first step in understanding zeitgeist for mathematics education in Korean mathematics teacher community according to changes of times over the past 10 years. Also, this study contributes to the methodological insights: the text mining technique provides a methodological contribution to researching changes in interests, values and zeitgeist according to these changes in the times.

• The Journal of Korean Philosophical History
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• no.35
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• pp.385-413
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• 2012

This thesis is a study on the relation of between Xiangshu Zhouyi Theory and mathematics, Zhouyi Theory as the one of the study of Chinese classics, was formed by Zhouyi' Eight Diagrams, the theory of Yinyangwuxing and the knowledge of natural science in Han dynasty. 'Xiangshu' had been regarded as the important concept and theory in the history of Zhouyi Theory From the beginning of Han dynasty to the end of Qing dynasty. At this developing of this Periodical Change, 'Xiangshu' had been endoded in the expression system of mathematics. This thesis considers binary system and surplus nembers, multiple and progression, magic square and circular constant, a proportional expression from Zhouyi Theory point of view. Xiangshu Zhouyi theory got the answer of these questions like the origin of Zhouyi, interpreting Guayao-word and Cosmology by using those expression systems of mathematics. Besides mathematics, Xiangshu Zhouyi theory was also related to astronomy, medicine, etc. Xiangshu Zhouyi theory had kept the pace with the general development of natural science. This thesis from the premise that Xiangshu Zhouyi theory kept the pace with natural science, summing up the mathematical expression system in the history of Zhouyi theory, proves that Xiangshu Zhouyi theory had developed according as the conditions of natural science.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.2 no.1
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• pp.178-210
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• 1974

It needs to put into practice the systems analysis in the analysis of some operations and status of library for the purpose of systematizing the work of reforming in the new easier form to process, to storage, to retrieve and to make use of the increasing informations and data of library. In this study, some of systems which are generally using in every library was caught in the case study of K university library. Having analyzed them with the two methods of the flowcharting and mathematical analysis, we found the obstructive factors in operation. As the result of this research, it was gained the new system as the alternative one. A. Alternative System B. Advantages of alternative systems 1. In the reference room When it converts the present system into the new system, it can profit 6.771 won/user (13.815won-7.044won=6.771 won). Therefore, a half the average required cost of the present system can be saved. If this saving would be alloted for the cost 33,000won required to make the cataloging cards, it would be taken for 94 days (33,000 won ${\div}$ 6,771 won/user=4,874users. 4,874users ${\div}$ 52users/day=94days) to get it. The saving cost/year by the new system will be 95,417 won, and in the first year the initial cost (33,000won) reduces the saving cost to 62,417won. 2. In the periodical room The average required time for using the materials of the present system is 17 minutes/user and the average required cost/user is 23.775won, while the average required time of the new system is 4 minutes and the average required cost/user is 5.33won. Therefore, the new system has profit 4 times of the present system. Accordingly, it occurs when the dispersed periodical materials get together. 3. In the classification and cataloging When one processes - the oriental books - by the Linear Programming Technique, the maximum of the process can be increased from 11.6 volumes per librarian of the present system to 12 volumes per librarian of the new system increased 0.4 volume in a day, and cataloging by the manual printer can be shorten from 3 minutes per card of the present system to 1.5 minutes per card of the new system. Consequently, we can complete the other operations (books equipment, updating of cataloging cards, etc.) with 141 minutes which are saved in the course of the afore-mentioned works. 4. In the status of collections The average growth rate of 4 years from 1968 to 1971 is 9.825 %, and that of the purchased materials is 6.2% similar to the advanced nations, but it has the different position from 215,000 volumes by the Standard Degree for Establishment of College and University, and the difference between the total collections 151,671 volumes and Dunns' growth model ($N_t=N_oe^{-at}$) claimed by Leimkuhler 155,297 volumes in 1971 is 3,626 volumes, and for the purpose of compensation the difference, we found the fact that it needs to have the increased budget of 24~30% per year, Thus, if the budget of 24~30 % per year. Thus, if the budget would be increased per year as the rate of the afore-mentioned figure, it would be reached at the Standard Degree for Establishment of College and University in 1975, and thereafter, it can be decreased to the lebel which is able to maintain the growth rate of 5~6% per year.