• The KIPS Transactions:PartB
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• v.9B no.3
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• pp.293-302
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• 2002

Gradual scene change detection is known as more difficult problem then abrupt scene change detection on video data analysis for contents based retrieval. In this paper, we present a new method for scene change detection far both abrupt and gradual change using the variable dynamic threshold arid cut frame difference (CFD). For this, We present the characteristics arid mathematical models of gradual transitions anti then, how can be detected by the CFD. And also we present new scene change detection algorithm based on cut frame difference. By the experimental result using real world video data indicate that the proposed method detect various scene changes both abrupt and gradual change efficiently without time-consuming computation and any dependency on a kind of gradual change effects.

• The Mathematical Education
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• v.61 no.3
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• pp.419-439
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• 2022

This study is based on Freudenthal's mathmatising process and the didactical phenomenology of linear function concept, I have described and examined the process in which students represent the constant rate of change into tables, graphs and equations and, in this way, how they construct mental objects and essence of the linear function concept. The students used the proportionality as composite units, when they represented the phenomenon with constant rate of change into tables. When representing in graphs, all but one student represented it into a line. There were differences among the students in the level they were using the given conditions, co-variation perspective, and corresponding rules when formulating equations. The students compared the relationship between two variables in a multiplicative way, and under the guidance of teachers they reached to the understanding that its relationship becomes a constant. Moreover, they could construct mental objects of a constant rate of change, understanding the situation where the relationship between time difference and distance difference becomes one value, namely speed. The students had difficulties in connecting the rate of change with the inclination of a line. The students constructed the essence (concept) of linear functions, after building and organizing the image that the rate of change is constant, the graph is linear, and the equation is formulated as y=ax+b (a: inclination, b: intercept).

• Journal of the korean Society of Automotive Engineers
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• v.7 no.2
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• pp.45-54
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• 1985

Recently, the problem of exhaust gas pollution is increasingly being aggravated by the active use of the Diesel engine. For the fuel-injection system which affects the composition of exhaust gas from the Bosch type single-hole nozzle in the Diesel engine, a mathematical model was set up to study pressure variations in the high pressure pipe, the injection rate, and the needle lift. The fundamental equations of the mathematical model have been solved by the Newton Raphson Method applying the Finite Diffrence Method. The effective stroke of the injection pump plunger due to a change in engine rpm was calculated by the measurement of Control Rack, Pinion, and Plunger sizes and by the use of Characteristic Curve of Governor. The computed results for the pressure variations in the high pressure pipe and needle lift at 800 rpm and 1000 rpm are in good agreement with experimental ones in general. By a developed program, the effects of other various parameters will by calculated for the performance of the fuel-injection system.

• Research in Mathematical Education
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• v.16 no.1
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• pp.31-50
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• 2012

The present study explored whether the implementation of focused activities (intervention programme) can enhance 22 pre-service mathematics teachers' proficiency in solid geometry thinking level as well as change for the better their feelings in this discipline. Over a period of 6 weeks the pre-service teachers participated in activities and diversified experiences with 3D shapes, using illustration aids and actual experience of building 3D shapes in relation to the various spatial thinking levels. The research objectives were to investigate whether the intervention programme, comprising task-oriented activities of solid geometry, enhance mathematics pre-service teachers' mastery of their geometric thinking levels as well as examine their feelings towards this discipline before and after the intervention programme. The findings illustrate that learners' levels of geometric thinking can be promoted, entailing control on higher thinking levels as well as a more positive attitude towards this field.

• Journal of Power System Engineering
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• v.16 no.3
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• pp.64-68
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• 2012

Because the magnetic bearing supports levitating body without contact, wear, noise and vibration are very small comparing with mechanical bearings, it is very useful to high revolution machinery. In general, the magnetic attractive force function that is proportional to square of control current(x), and inversely proportional to square of an air gap(i) has been widely used. This paper proposed the new magnetic attractive force function that is proportional to cube of the control current, and inversely proportional to square of the air gap. The function was optimized to minimize the cost function that is the percentage of deviation about the change of a proportional constant(k), using the experimental data, ie, control currents and air gaps.

• Research in Mathematical Education
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• v.19 no.4
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• pp.211-227
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• 2015

Information Technology influenced on classroom to change the teaching and learning method. Recently, flipped learning method became a hot issue in education by using Information Technology. Learning management system that is introduced in our university in the spring semester 2015, made it possible to apply flipped learning method. So, we used the flipped learning method in a calculus course. In this paper, we found that flipped learning in Calculus we was a little bit affirmative in the aspect of motivation and active learning from students' response on flipped learning method. We analyzed the reason that students were not so positive in continuing flipped learning even though they liked flipped learning a little bit better than traditional learning. We suggest what we pay attention to for applying the flipped learning method effectively.

• Honam Mathematical Journal
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• v.39 no.4
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• pp.575-590
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• 2017

A new class of functions called $R_{\theta}$-supercontinuous functions is introduced. Their basic properties are studied and their place in the hierarchy of strong variants of continuity, which already exist in the literature, is elaborated. The class of $R_{\theta}$-supercontinuous functions properly contains the class of $R_z$-supercontinuous functions [39] which in turn properly contains the class of $R_{cl}$-supercontinuous functions [43] and so includes all cl-supercontinuous (clopen continuous) functions ([38], [34]) and is properly contained in the class of $R_{\delta}$-supercontinuous functions [24].

• East Asian mathematical journal
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• v.34 no.4
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• pp.487-509
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• 2018

We analyse the map of the west capital Pyongyangbu of Old Korea(AD 920) by topological method and geometrical method and compare it with the map of North Korea Pyongyang. By the analyse of the map we find the real place of the old map. The analysing and finding the real place of the old map is a very good example of geometry education. Many Koreans had learned and recognized that Old Korea(AD 920) was a small country located in the south part of Ablok river. But, after reading this paper they change their old recognitions and they take prides in Great Old Korea.

• Journal of the Korean Mathematical Society
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• v.35 no.3
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• pp.659-673
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• 1998

In this paper we consider a security market whose asset price process is a vector semimartingale. The market is said to be fair if there exists an equivalent martingale measure for the price process, deflated by a numeraire asset. It is shown that the fairness of a market is invariant under the change of numeraire. As a consequence, we show that the characterization of the fairness of a market is reduced to the case where the deflated price process is bounded. In the latter case a theorem of Kreps (1981) has already solved the problem. By using a theorem of Delbaen and Schachermayer (1994) we obtain an intrinsic characterization of the fairness of a market, which is more intuitive than Kreps' theorem. It is shown that the arbitrage pricing of replicatable contingent claims is independent of the choice of numeraire and equivalent martingale measure. A sufficient condition for the fairness of a market, modeled by an Ito process, is given.

• Journal of the Korean Mathematical Society
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• v.34 no.4
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• pp.973-1008
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• 1997

We reconsider the problem of calssifying all classical orthogonal polynomial sequences which are solutions to a second-order differential equation of the form $$ \ell_2(x)y"(x) + \ell_1(x)y'(x) = \lambda_n y(x). $$ We first obtain new (algebraic) necessary and sufficient conditions on the coefficients $\ell_1(x)$ and $\ell_2(x)$ for the above differential equation to have orthogonal polynomial solutions. Using this result, we then obtain a complete classification of all classical orthogonal polynomials : up to a real linear change of variable, there are the six distinct orthogonal polynomial sets of Jacobi, Bessel, Laguerre, Hermite, twisted Hermite, and twisted Jacobi.cobi.