• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.2
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• pp.102-109
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• 2000

This paper describes two different theories used to model the scattering of ultrasound by a volumetric flaw and a crack-like flaw. The elastodynamic Kirchhoff approximation (EKA) and the geometrical theory of diffraction (GTD) are applied respectively to a cylindrical cavity and a semi-infinite crack. These methods are known as high frequency approximations. The 2-D elastodynamic scattering problems of a plane wave incident on these model defects are considered and the scattered fields are expressed in terms of the reflection and diffraction coefficients. The ratio of the scattered far field amplitude to the incident wave amplitude is computed as a function of the angular location and compared with the boundary element solutions.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.3
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• pp.65-72
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• 2001

Generally, it is said that control of the inertia system is to track the reference input quickly while suppressing the vibration due to the system itself. In this case, the difficulty fur designing a controller is caused by modeling uncertainty and parameter variation. The purpose of this paper is to propose a design method to suppress the vibration of three-mass inertia system based on the LMI theory. That is, the generalized plant model by which we can cope with conservativeness of the existing H$_{*}$ theory is proposed and analyzed in terms of LMI. The results of simulation fur the three-mass inertia system show that the proposed design approach is quite effective under the given situations.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.3
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• pp.419-426
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• 1986

In an attempt to develop a method for the design of the aerial rope way, the traditional theories of rope way were examined and compared. The resulting formulas of the traditional and approximate parabolic curve theory were summarized and those of the catenary curve theory as an exact ones were summarized and newly developed when necessary. In particular, it was found that the resulting formulas from both of these theories can fully be expressed with only three dimensionless parameters $U^{*}$, $V^{*}$, and $W^{*}$, improving compactness and generality of these formulas. Comparision of the theories were done through error analysis, and it was shown that the error of the approximate parabolic curve is of order $U^{*2}$ and $V^{*}$. From this, it was concluded that the traditional parabolic curve theory has its limitation when the rope way becomes larger or steeper, leading to the necessity of the use of catenary curve theory.ve theory.

• Journal of Korean Society of Transportation
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• v.24 no.7 s.93
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• pp.139-148
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• 2006

In order to incorporate substitution effects between different transport modes in optimal road Pricing, relating economic theories and models have been reviewed. It includes unconstrained optimization problem of maximizing separable and non-separable social net benefit functions of different substitutable urban transport modes. In doing that, the problem and limitations such as path-independent conditions with the asymmetric Jacobian of the objective function have been reviewed. Consequently, a plausible way of deriving optimal road price under interdependent market conditions has been suggested so that the idea can help identifying desirable and acceptable urban transport policy alternatives in a more comprehensive way.

• Journal of the Korean association of regional geographers
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• v.13 no.3
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• pp.254-270
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• 2007

The concept of Regional Innovation System(RIS) has been developed with the accumulation of empirical research and the reflection on the political and economic environments. It is widely used as a nonnative concept to tackle the problem of regional disparities by enhancing regional innovative development. However, it seems that there is a gap between the theoretical framework of RIS and its actual application in reality. This paper attempts to extend our knowledge about RIS with critical viewpoint. It tries to unravel some values that RIS implies and its theoretical limitations, which were found through the evolution of RIS such as its theoretical roots, the development of its research and policy; and an example of its building in practice.

• Korean Journal of Logic
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• v.17 no.3
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• pp.399-424
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• 2014

The main objective of this paper is to examine critically White's claim that there is a conflict between Perceptual Dogmatism and Bayesian Theory of Confirmation. For this purpose, this paper is structured as follows: In Section 2, I will introduce White's argument. Section 3 is dedicated to explaining some elements of Bayesian Theory of Confirmation. In particular, I will provide an explanation of confirmation measures and Bayesian Favoring. Using these two conceptual apparatuses, it will be shown that, contrary to what White has thought, there is a way of supporting Perceptual Dogmatism by means of Bayesian Theory of Confirmation - in particular, Bayesian Theory of Favoring.

• Journal of Internet Computing and Services
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• v.8 no.6
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• pp.127-133
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• 2007

The u-learning environment has been developed through a number of iterations, and has now been formally evaluated, through analysis of student learning results and the use of quantitative and qualitative measures, Generally, for advance learning effect and analysis of student learning results, the most learning system be use to the item analysis method. But, nowadays, it has using the IRT(Item Response Theory) instead of the item analysis method, The IRT adopts explicit models for the probability of each possible response to a test. Therefore, I proposed the lightweight component based u-learning system using the IRT. Applied device of u-learning is PDA which is in Windows mobile 5.0 environments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.1
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• pp.87-93
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• 2002

The previous RST postulates that the scattering field, within each modal partial wave, comprise of the resonance and the background components. The new RST is recently developed by the product expansion of the scattering functions in the field of acoustics. The new formulation suggests that the scattering coefficients consist of resonance, non-resonance, and their interactional portions. In the scattering problems of acoustic waves, the moduli and phase of the resonance coefficient are obtained correctly by the new RST. In our recent works the new RST was successfully applied to the scattering problem of electromagnetic waves for coated conducting cylinder and sphere. In this paper, the new RST is extended to the 2-dimensional scattering problem of electromagnetic waves for a homogeneous dielectric cylinder, and the numerical results are compared with the previous RST.

• School Mathematics
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• v.18 no.2
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• pp.375-396
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• 2016

This study considered Elementary school textbook and teacher's manual in Korea in terms of theories on counting. First we considered the meaning of counting in elementary school mathematics based on many preceding researches. And we compared textbooks in Korea with foreign textbooks in Singapore, China, USA. As a result, compared with Korea, these foreign textbooks reflect the theories on counting more actively. First of all, they consider counting to be an important basis for the four operations. Teacher's manual in Korea introduces the theories on counting, but the content was limited and thread was not clear. Based on these consideration, We discussed reflection of elementary school textbook in terms of theories on counting.

• The Journal of the Korea Contents Association
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• v.21 no.8
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• pp.537-545
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• 2021

We hypothesize work jealousy can moderate the relationship between leader-member exchange (LMX) and two different work behaviors, counterproductive work behavior(CWB) and organizational citizenship behavior (OCB). The results supported our hypotheses and found an interaction between LMX and work jealousy such that the relationship between LMX and CWB is negative when jealousy is higher but not when jealousy is lower. We did not find an interaction between LMX and work jealousy on OCB, however. We test our hypotheses in a service organizational sample consisting of one hundred thirty-nine. Managerial implications and directors for future research are discussed.