• Korean Journal of Logic
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• v.16 no.1
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• pp.45-59
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• 2013

In his book Worlds and Individuals: Possible and Otherwise, Takashi Yagisawa Yagisawa argues that his own theory is better than Lewis's theory by showing that his own theory can deal with important objections to modal realism more successfully than Lewis's. In particular, Yagisawa claims that by adopting modal tenses, he can respond to many important objections to modal realism in a uniform way. In this paper, I argue that Lewis can also successfully respond to Peacocke's objection in an exactly parallel way to Yagisawa's by distinguishing existence at the actual world from existence at other possible worlds and that Yagisawa's response to van Inwagen's objection does not succeed. I conclude that Yagisawa fails to show that his own theory is better than Lewis's.

• Journal of the Korean Mathematical Society
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• v.40 no.4
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• pp.695-708
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• 2003

We study the existence of solutions for overdetermined PDE systems that admit prolongation to a complete system. We reduce the problem to a Pfaffian system on a submanifold of the jet space of unknown functions and then express the integrability conditions in terms of the coefficients of the original system. As possible applications we present some local problems in CR geometry: determining the CR embeddibility into spheres and the existence of infinitesimal CR automorphisms.

• Communications for Statistical Applications and Methods
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• v.11 no.2
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• pp.413-418
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• 2004

Statistically illiterate people seem to believe that there are some strategies for choosing winning numbers in lottery. One seemingly plausible strategy is to select the hot numbers which most frequently appeared in the past. In this article we investigate the existence of hot numbers in the Korean national lottery called Lotto. A numerical method is proposed to estimate the exact sampling distribution of test statistic for checking the existence of hot numbers among 45 possible numbers of choice.

• Journal of Multimedia Information System
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• v.8 no.2
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• pp.131-142
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• 2021

This paper traces the process of constructing a new one-dimensional chaotic map, and will provide a simple application in color image encryption. The use of Sarkovskii's theorem will make it possible to determine the existence of chaos and restrict all conditions to ensure the existence of this new sequence. In addition, the sensitivity to initial conditions will be proved by Lyapunov's index value. Similarly, the performance of this new chaotic map will be illustrated graphically and compared with other chaotic maps most commonly used in cryptography. Finally, a humble color image encryption application will show the power of this new chaotic map.

• Journal for History of Mathematics
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• v.30 no.2
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• pp.87-100
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• 2017

The ontological status of Newtonian space-time has been debated under the name of substantivalism-relationism controversy. The debates between the two parties are concerned with the nature of existence of space-time. Substantivalism maintains that the points of space-time have existence analogous to material substance. Relationism claims that space-time should be understood as the framework of possible spatio-temporal relations between bodies. Newtonian space is considered as a three dimensional entity in accordance with our geometric common sense. Yet given that the concept of motion is defined as the change of position throughout time, it is possible to interpret space-time as a 4 dimensional entity. In this essay, substantivalist-relationist debate is considered within the context of non-relativistic 4 dimensional space-time theory. This essay attempts to clarify the dispute over the ontology of space-time by elucidating the relationship between the ontology of space-time, motion, and space-time symmetry.

• 대한생식의학회:학술대회논문집
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• 2001.11a
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• pp.91-91
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• 2001

• Journal of applied mathematics & informatics
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• v.38 no.5_6
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• pp.375-406
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• 2020

The anti-predator factor due to fear of predator in eco- epidemiological models has a great importance and cannot be evaded. The present paper consists of a modified Lesli-Gower predator-prey model with contagious disease in the predator population only and also consider the fear effect in the prey population. Boundedness and positivity have been studied to ensure the eco-epidemiological model is well-behaved. The existence and stability conditions of all possible equilibria of the model have been studied thoroughly. Considering the fear constant as bifurcating parameter, the conditions for the existence of limit cycle under which the system admits a Hopf bifurcation are investigated. The detailed study for direction of Hopf bifurcation have been derived with the use of both the normal form and the central manifold theory. We observe that the increasing fear constant, not only reduce the prey density, but also stabilize the system from unstable to stable focus by excluding the existence of periodic solutions.

• Journal of the Korean Mathematical Society
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• v.33 no.1
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• pp.25-29
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• 1996

The Debreu-Gale-Nikaido theorem [2] is a potential tool to prove the existence of a market equilibrium price. Walras' law is of a quantitative nature (i.e. it measures the value of the total excess demand), and it is interesting to note that the existence result holds true under some qualitative assumptions. In fact, the Debreu-Gale-Nikaido theorem states that the continuity of the excess demand function and Walras' law has the following implication : For some price and corresponding value of the excess demand function, it is not possible to respond with a new price system such that the value at the new price of every element in the value of the demand function associated with the old price system is strictly positive.

• The Journal of the Korea Contents Association
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• v.21 no.4
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• pp.833-841
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• 2021

This study was an entertainer who was in charge of female music in the Joseon Dynasty, but the existence of gisaengs, who were recognized as'sexual partners' of the four grandfathers, and the Joseon Dynasty, when their existence was possible. I tried to reveal the social characteristics of Therefore, the research is meaningful in that it attempted to reveal the relationship between the grandfather and the gisaeng from various perspectives, and that it is possible to confirm the various social roles of the gisaeng. In the Confucian society, female musicians were not allowed to participate in Naeyeon and Chinjamrye, where women were the main pillars, so not only could the girl's music survive until the end of the Joseon Dynasty, but it was enough to reveal the existence of a professional artist. The existence of gisaengs is not irrelevant to the social background of the Joseon Dynasty, and therefore, it is impossible to define the Joseon Dynasty with the holy morality of modern society. It is believed that 『catching green onions is expected to enhance the aspect of a gisaeng as a celebrity, based on the interpretation that it is viewed from the perspective of an entertainer possessing an extraordinary and noble spirit rather than portraying the gisaeng in an erotic standard.

• Journal of Welding and Joining
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• v.5 no.4
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• pp.22-27
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• 1987

The debonding of clad steel was often occurred at interface between stainless steel and carbon steel during the fabrication of pressure vessel. In order to clarify the causes of debonding phenomena, the fabrication sequences were fully analyzed. As a result, possible factors were noticed for causing the debonding of clad steel, that is, thermal treatment on weldment and welding. Moreover the existence of hydrogen diffused from surroundings also expedites the debonding of clad steel. In this stud, the effect of welding thermal cycle, hydrogen and mixed condition under thermal treatment on the interfacial strength of clad steel were investigated to understand the debonding mechanism of clad steel. From this study, it has been confirmed that the interfacial strength of clad steel was remarkablely deteriorated due to welding and/or existence of hydrogen under thermal treatment. In the case of welding thermal cycle effect, the higher temperature at interface experienced by welding, the more reduction in interfacial strength of clad steel resulted in. And the existence of diffusible hydrogen also reduced the interfacial strength. It is also found that the interfacial strength of clad steel became much lower value than that of the as-received plate under coexistence of above mentioned factors.