• East Asian mathematical journal
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• v.40 no.1
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• pp.75-83
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• 2024

For a reduced, irreducible and nondegenerate curve C ⊂ ℙ^r of degree d, it was shown that the arithmetic genus g of C has an upper bound π₀(d, r) by G. Castelnuovo. And he also classified the curves that attain the extremal value. These curves are arithmetically Cohen-Macaulay and contained in a surface of minimal degree. In this paper, we investigate the arithmetic genus of curves lie on a surface of minimal degree - the Veronese surface, smooth rational normal surface scrolls and singular rational normal surface scrolls. We also provide a construction of curves on singular rational normal surface scroll S(0, 2) ⊂ ℙ³ which attain the maximal arithmetic genus.

• The Mathematical Education
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• v.48 no.1
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• pp.81-91
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• 2009

This paper focuses on two problems in the 10th grade mathematics, the rational zero theorem and the content(the integer divisor) of a polynomial Among 138 students participated in the problem solving, 58 of them (42 %) has used the rational zero theorem for the factorization of polynomials. However, 30 of 58 students (52 %) consider the rational zero theorem is a mathematical fake(false statement) and they only use it to get a correct answer. There are three different types in the textbooks in dealing with the content of a polynomial with integer coefficients. Computing the greatest common divisor of polynomials, some textbooks consider the content of polynomials, some do not and others suggest both methods. This also makes students confused. We suggests that a separate section of the rational zero theorem must be included in the text. As for the content of a polynomial, we consider the polynomials are contained in the polynomial ring over the rational numbers. So computing the gcd of polynomials, guide the students to give a monic(or primitive) polynomial as ail answer.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.1-17
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• 2014

Cooperative spectrum sensing (CSS) is considered as a powerful approach to improve the utilization of scarce radio spectrum resources. However, most of CSS schemes assume all secondary users (SU) are honest, and thus offering opportunities for malicious SUs to launch the spectrum sensing data falsification attack (SSDF attack). To combat such misbehaved behaviors, recent efforts have been made to trust schemes. In this paper, we argue that powering CSS with traditional trust schemes is not enough. The rational SSDF attack is found in this paper. Unlike the simple SSDF attack, rational SSDF attackers send out false sensing data on a small number of interested primary users (PUs) rather than all PUs. In this case, rational SSDF attackers can keep up high trustworthiness, resulting in difficultly detecting malicious SUs in the traditional trust schemes. Meanwhile, a defense scheme using a novel trust approach is proposed to counter rational SSDF attack. Simulation results show that this scheme can successfully reduce the power of rational SSDF, and thus ensure the performance of CSS.

• Journal of Korea Port Economic Association
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• v.34 no.3
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• pp.183-200
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• 2018

This study empirically tests the presence of rational bubbles in the ship prices using time series data from October 1996 to April 2017. To detect the existence of ship prices' rational bubbles, we use integration and cointegration tests, which were proposed by Campbell and Shiller(1987) and Diba and Grossman(1988), for circumventing misspecification of ship price model and applying the bubble test to nonstationary time series. The result of integration test supports existence of tanker price's rational bubble. The co-integration test also shows that drybulk ship and containership prices have been overvalued relative to the market fundamental, drybulk and container freight rates, due to non-stationary rational bubbles. These results provide Korean shipping industry and authorities implications that anticyclical ship investment and long-term and steady fleet capacity expansion policy are needed.

• Journal of Korean Home Economics Education Association
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• v.31 no.4
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• pp.115-128
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• 2019

The purpose of this study was to examine the influence of self-esteem and consumer socialization agents on rational consumption patterns of middle school students. Using a convenient sampling method, the data were collected from middle schools in Seoul, Gyeonggi, Chungcheong, Jeonnam, and Gwangju and a total of 412 copies were analyzed. The descriptive statistics, Chronbach's α, t-test, and stepwise regression analysis were performed using the SPSS and the results were as follows. First, rational consumption behavior was 3.18 and self-esteem was 3.54 on a 5-Likert scale. As for consumer socialization agents, parents was the highest at 3.13, followed by school 2.83, mass media 2.78 and peers 2.73. Second, the average comparison of rational consumption behavior and consumer socialization agents by gender showed that there was no gender difference in rational consumption behavior, but in the case of consumer socialization, girls were higher than boys. Third, examining the influence of self-esteem and consumer socialization agents on rational consumption behavior, it was found that the amount of money, mass media, and peers showed an negative effects on rational consumption behavior, while self-esteem and parents showed positive effects on rational consumption behavior. In this regard, middle school students need to have more self-esteem and guide their peers so that their influence can be positive in the home economics class in order to become consumers with rational consumption behavior.

• Journal of Digital Convergence
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• v.10 no.3
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• pp.179-189
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• 2012

The purpose of this study examines the influence of brand concepts(symbolic vs. functional) and thinking styles(holistic vs. analytic) on the attitude toward extension ads.(rational/emotional) and product. The moderating effect of thinking styles was also tested. The results of this study are as follows: I) Brand concepts of parent brand had a significant effect on the attitude toward extension ads.(symbolic: no differences between rational and emotional ads., functional: rational ads. > emotional ads.) and extension product. 2) Thinking styles of consumers also did.(holistic: no differences between rational and emotional ads., analytic: rational > emotional ads.) and extension product. 3) The moderating effect of thinking styles was(rational ads.: symbolicfunctional).

• Proceedings of the Korean Society of Rheology Conference
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• 2002.11a
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• pp.101-103
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• 2002

• Journal of applied mathematics & informatics
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• v.6 no.3
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• pp.771-771
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• 1999

• Journal of Families and Better Life
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• v.26 no.5
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• pp.241-257
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• 2008

The purpose of this study waw to investigate the effect of consumer knowledge of adolescents, money attitudes and consumption values on rational consumption behavior and the direct and indirect effects of these variables on rational consumption behavior. The subjects of this study were 524 students who were in the first grade and second grade of high school in Daegu. Multiple Regression Analysis and Path Analysis were employed for the data analysis. The major findings of this study were as follows: First, the knowledge of money management, the purchase knowledge and the consumerism knowledge effected on the money attitude, which regarded money as an instrument of future safety. Among these, it was found that the money management knowledge had the highest affect on this money attitude. The result suggests that the consumer knowledge affects desirable money attitude which regarded money as an instrument of future safety, and then consumer education influences positively money attitude. Second, the money attitude which regarded money as an instrument of future safety affected consumption values most, and the money attitude which regarded money as a means for approval of another person affected the ostentation, the conformity, the discrimination and the aesthetic enjoyment of consumption values. Third, the present study showed that the money attitude which regards money as an instrument of future safety and the economical consumption values were the important factor which affecting each subdimension of the rational consumption behavior. The result suggests the adolescents, who managed money well, saved it for the future, and saved the resources as much as possible when consuming, behaved rational and planned way through all process all process all consumption behaviors. Fourth, the consumer knowledge did not affect the rational consumption behavior directly, but indirectly through the money attitude and the consumption values. Therefore, the consumer knowledge, the money attitude and the consumption values were the important factor for the rational consumption behavior, and it revealed money attitude and consumption values played role as mediate variable. This study results suggest the consumer knowledge that adolescent have learned in school was theoretical and abstract, so it does not affect directly the rational consumption behavior. However these consumer consumption values affect the consumption behavior.

• Journal of the Korean School Mathematics Society
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• v.10 no.2
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• pp.237-246
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• 2007

According to 7-th curriculum, irrational number should be introduced using non-repeating infinite decimals. A rational number is defined by a number determined by the ratio of some integer p to some non-zero integer q in 7-th grade. In 8-th grade, A number is rational number if and only if it can be expressed as finite decimal or repeating decimal. A irrational number is defined by non-repeating infinite decimal in 9-th grade. There are misconceptions about a non-repeating infinite decimal. Although 1.4532954$\cdots$ is neither a rational number nor a irrational number, many high school students determine 1.4532954$\cdots$ is a irrational number and 0.101001001$\cdots$ is a rational number. The cause of misconceptions is the definition of a irrational number defined by non-repeating infinite decimals. It is a cause of misconception about a irrational number that a irrational number is defined by a non-repeating infinite decimals and the method of using symbol dots in infinite decimal is not defined in text books.