• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.1
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• pp.66-72
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• 2014

In this paper, we establish common fixed point theorem for type(${\beta}$) compatible four mappings with implicit relations defined on an intuitionistic fuzzy metric space. Also, we present the example of common fixed point satisfying the conditions of main theorem in an intuitionistic fuzzy metric space.

• International Journal of Reliability and Applications
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• v.8 no.2
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• pp.175-182
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• 2007

In this note, some comments concerning the testing procedures for the problems of stochastic comparison, testing IFR and testing NBU ageing properties are presented showing that the tests proposed in Belzunce, Candel and Ruiz(1998) are cumbersome to calculate and do not have as good asymptotic Pittman efficacies as simpler others already in the literature. This is done via new presentations of the measures on which Belzunce et al. base their tests.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.11 no.2
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• pp.108-112
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• 2011

Kaneko et a1.[4] etc many authors extended with multi-valued maps for the notion of compatible maps in complete metric space. Recently, O'Regan et a1.[5] presented fixed point and homotopy results for compatible single-valued maps on complete metric spaces. In this paper, we will establish some common fixed point theorems using compatible maps in intuitionistic fuzzy metric space.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.4 no.2
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• pp.39-54
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• 1994

In cryptography, the notion of zero-knowledge is important. It is also related to complexity theory. In this paper we briefly survey the zero-knowledge proofs in the literature. 1987 Maathematics Subject Classification: 69D56, 69E30, 69F21, Keywords and phrases: interactive proofs, zero-kniwledge, cryptography, complexity theiry.

• Journal of the Korean School Mathematics Society
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• v.9 no.4
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• pp.575-595
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• 2006

In this paper, we investigated the effects of mathematics classes using play-action programs in the course of mathematics education of future elementary school teachers. This study was conducted with 43 junior university students who selected 'Play Mathematics' in 2006. All the participants in this course was divided 11 groups. Play-action mathematics programs was consisted of 12 themes. For example, there was tangram, somacube, hexamino, tessellation, geoboard etc. In the beginning of lessons, we investigated theses themes itself through plays, puzzles, games, and computer programs. And next time, we investigated the relationships between these themes and elementary mathematic textbooks(i.e. mathematical contents). In 14th and 15th lessons, all the groups took a project presentation lessons that included all things about play mathematics in all group categories. And they developed two themes of play mathematics in accordance with grades, contents, levels as course tasks. Through this study, three educational effects induced. First, future elementary school teachers have a deep understanding about play-action mathematics. They are interested in these play themes, and take part in these play mathematics programs of their own accord. And they realize that these play themes are related to elementary mathematics. Second, future elementary school teachers' attitude and mind about mathematical are improved after this course. Third, future elementary school teachers comprehend various instruction methods relating to play mathematics. Therefore, we suggest that future elementary school teachers need to have many opportunity to experience and develop a mathematics classes using play mathematics.

• Journal of the Korean Institute of Navigation
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• v.1 no.1
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• pp.27-44
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• 1977

The Maneuvering Indices of a ship are the values that decide the quantity of her motion in turning when her rudder is turned over to an angle to the starboard or the port. They consist of two kinds of indices, one of which is called index K and the other, index T. Index K decides a ship's turning ability and index T does the length of time delay of a normal turning motion after her rudder has finished the turn of an ordered angle. Generally, the values of the indices are calculated through some mathematic formulas with figures of her heading degrees recorded at a fixed time intervals during her Z test. The values of the same kind index of a ship appear differently according to the ship'sspeed, trim, rudder angle and loaded condition, etc. In this paper, the author analyzed all the amthematic formulas required to calculate the values of the indices in their forming process and examined them from the point of mathematics and dynamics and also actually figured out the values of maneuvering indices of the M.S. "HANBADA", the training ship of Korea Merchant Marine College through her Z test. The author supposed a case in which two same typed ships as the "HANBADA" in size, shape and conditions were approaching each other in meeting end on situation and each ship turned her rudder hard over to the starboard respectively when they approached to the distance of 3 times as long as the ship's length. The author worked out mathematic formulas calculating forward and transverse ship's motions within the above mentioned situation for the quantative analysis of the collision avoding action to certify whether they are in collision status or not. Applying the calculated values of the maneuvering indices of the "HANBADA" to the motion calculating formulas, the author found out the two ships were passing over each other with the clearing distance o 39m between their port quarters. With the above mentioned examinations and explanations, the author demonstrated that a ship's motion in any collision avoiding action can be shown with quantities of time and distance within reliable limit.istance within reliable limit.

• Journal of the Korean School Mathematics Society
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• v.18 no.3
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• pp.281-309
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• 2015

The purpose of this study is provides an implication of further teaching learning process by analyze the common and difference and characteristic of mathematical self-efficiency between three peer tutoring groups discourse in the mathematical teaching leaning process that use peer tutoring. To achieve this goal, three groups formed that consist of one peer tutor who received a first grade of mathematic achievement and one peer student. Peer student of each group is divided into high grade, middle grade, low grade of mathematic achievement. Then analyze the discourse in the exponential function problem solving process. Based on the results of study, this paper provides a concrete example of merit of peer tutoring on the peer tutor. Result of study also provides a practical help to make a peer tutoring group by considering a difference of grades between peer tutor and peer student. Because there is a possibility of mutual discourse on the tutoring group that consist of similar grades.

• Journal of the Korean School Mathematics Society
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• v.14 no.1
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• pp.31-42
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• 2011

The purpose of this study is to explore how elementary mathematics teachers' adaptations of a reform-oriented mathematics curriculum material in the USA, Everyday Mathematics, influence elementary students' opportunities to learn mathematics. I illustrate how elementary mathematics teachers alter the curriculum material and how such alterations influence their students' opportunities to learn mathematics in their mathematics classrooms. Results suggest that the teachers with Everyday Mathematics did not appear to maintain the cognitive demand of mathematical tasks as appeared in the curriculum material, as set up by the teacher, and as enacted in the classrooms. The results also show that the teachers seemed to omit components including important tasks and suggestions in the curriculum material. As a consequence, the students did not have an opportunity to think and understand mathematics conceptually and meaningfully; they were exposed and encouraged to learn mathematics procedurally.

• Journal for History of Mathematics
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• v.19 no.4
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• pp.31-62
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• 2006

In this article, the theoretical basis of applying mathematical his tory in lessons is inquired in various educational aspects. It also covers the psychological genetic principle, mainly concerning the childish development and states that it has to be compatible with the historico-genetic principle, which is suggested mainly concerning the development of data. In addition, it evolves the arguments about the meaning of mathematical history in math lessons based on the mentioned aspects besides that in ordinary math lessons. Next, the link between the apply of mathematical history and education for gifted children is examined. Last, cases of mathematic history applied to mathematic education is suggested mainly concerning the understanding of differential concepts.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2119-2128
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• 2016

Due to detection and control errors, some high-frequency harmonics with voltage-source characteristics cause circulating currents in modular inverters. Moreover, the circulating currents are usually affected by the output filters (OF) of each module due to their filter and resonance properties. The interaction among the circulating currents in the modules increase the power loss and reduce system stability and control precision. Therefore, this paper reports the results of a study on the SPWM high-frequency harmonics circulating currents for a double-module VSI. In the paper, an analysis of the circulating-current circuits is briefly described. Next, a mathematic model of the single-module output voltage based on the carrier frequency of SPWM is built. On this basis, through mathematic modeling of high-frequency harmonic circulating currents, the formation mechanism and distribution characteristics of circular currents and their influences are studied in detail. Finally, the influences of the OF on the circulating currents are studied by mainly taking an LC-type filter as an example. A theoretical analysis and experimental results demonstrate some important characteristics. First, the carrier phase shifting of the SPWM for each module is the major cause of the SPWM harmonic circulating currents, and the circulating currents are in an odd distribution around n-times the carrier frequency $n{\omega}_s$, where n = 1, 2, 3, ${\ldots}$. Second, the harmonic circular currents do not flow into the parallel system. Third, the OF can effectively suppress the non-circulating part of the high-frequency harmonic currents but is ineffective for the circulation part, and actually reduces system stability.