• Title/Summary/Keyword: reduction theory

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REDUCTION METHOD APPLIED TO THE NONLINEAR BIHARMONIC PROBLEM

  • Jung, Tacksun;Choi, Q-Heung
    • Korean Journal of Mathematics
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    • v.18 no.1
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    • pp.87-96
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    • 2010
  • We consider the semilinear biharmonic equation with Dirichlet boundary condition. We give a theorem that there exist at least three nontrivial solutions for the semilinear biharmonic boundary value problem. We show this result by using the critical point theory, the finite dimensional reduction method and the shape of the graph of the corresponding functional on the finite reduction subspace.

Drinfeld modules with bad reduction over complete local rings

  • Bae, Sung-Han
    • Bulletin of the Korean Mathematical Society
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    • v.32 no.2
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    • pp.349-357
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    • 1995
  • In the theory of elliptic curves over a complete field with bad reduction (i.e. with nonintegral j-invariant) Tate elliptic curves play an important role. Likewise, in the theory of Drinfeld modules, Tate-Drinfeld modules replace Tate elliptic curves.

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LERAY-SCHAUDER DEGREE THEORY APPLIED TO THE PERTURBED PARABOLIC PROBLEM

  • Jung, Tacksun;Choi, Q-Heung
    • Korean Journal of Mathematics
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    • v.17 no.2
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    • pp.219-231
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    • 2009
  • We show the existence of at least four solutions for the perturbed parabolic equation with Dirichlet boundary condition and periodic condition when the nonlinear part cross two eigenvalues of the eigenvalue problem of the Laplace operator with boundary condition. We obtain this result by using the Leray-Schauder degree theory, the finite dimensional reduction method and the geometry of the mapping. The main point is that we restrict ourselves to the real Hilbert space instead of the complex space.

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ASYMPTOTICALLY LINEAR BEAM EQUATION AND REDUCTION METHOD

  • Choi, Q-Heung;Jung, Tacksun
    • Korean Journal of Mathematics
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    • v.19 no.4
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    • pp.481-493
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    • 2011
  • We prove a theorem which shows the existence of at least three ${\pi}$-periodic solutions of the wave equation with asymptotical linearity. We obtain this result by the finite dimensional reduction method which reduces the critical point results of the infinite dimensional space to those of the finite dimensional subspace. We also use the critical point theory and the variational method.

Fuzzy Modeling by Genetic Algorithm and Rough Set Theory (GA와 러프집합을 이용한 퍼지 모델링)

  • Joo, Yong-Suk;Lee, Chul-Heui
    • Proceedings of the KIEE Conference
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    • 2002.11c
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    • pp.333-336
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    • 2002
  • In many cases, fuzzy modeling has a defect that the design procedure cannot be theoretically justified. To overcome this difficulty, we suggest a new design method for fuzzy model by combining genetic algorithm(GA) and mush set theory. GA, which has the advantages is optimization, and rule base. However, it is some what time consuming, so are introduce rough set theory to the rule reduction procedure. As a result, the decrease of learning time and the considerable rate of rule reduction is achieved without loss of useful information. The preposed algorithm is composed of three stages; First stage is quasi-optimization of fuzzy model using GA(coarse tuning). Next the obtained rule base is reduced by rough set concept(rule reduction). Finally we perform re-optimization of the membership functions by GA(fine tuning). To check the effectiveness of the suggested algorithm, examples for time series prediction are examined.

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Application of Phase-Field Theory to Model Uranium Oxide Reduction Behavior in Electrolytic Reduction Process (전해환원 공정의 우라늄 산화물 환원 거동 모사를 위한 Phase-Field 이론 적용)

  • Park, Byung Heung;Jeong, Sang Mun
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.16 no.3
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    • pp.291-299
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    • 2018
  • Under a pyro-processing concept, an electrolytic reduction process has been developed to reduce uranium oxide in molten salt by electrochemical means as a part of spent fuel treatment process development. Accordingly, a model based on electrochemical theory is required to design a reactor for the electrolytic reduction process. In this study, a 1D model based on the phase-field theory, which explains phase separation behaviors was developed to simulate electrolytic reduction of uranium oxide. By adopting parameters for diffusion of oxygen elements in a pellet and electrochemical reaction rate at the surface of the pellet, the model described the behavior of inward reduction well and revealed that the current depends on the internal diffusion of the oxygen element. The model for the electrolytic reduction is expected to be used to determine the optimum conditions for large scale reactor design. It is also expected that the model will be applied to simulate the integration of pyro-processing.

A new rotational force model for quasi-steady theory of plate-like windborne debris in uniform flow

  • Lin, Huatan;Huang, Peng;Gu, Ming
    • Wind and Structures
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    • v.35 no.2
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    • pp.109-120
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    • 2022
  • The force coefficients of rotating plates in the acceleration stage will vary with rotation rate from 0 to stable rotation rate w0, which are important for quasi-steady theory of plate-like windborne debris to simulate the trajectory. In this paper, a wind tunnel experiment is carried out to study the effects of geometry and the Reynolds number on the variations of mean force coefficients of rotating plates. The rotational lift coefficients are sensitive to both geometry effect and Reynolds number effect, while the rotational drag and moment coefficients are only sensitive to geometry effect. In addition, new empirical formulas for the rotational lift coefficient and moment coefficients are proposed. Its accuracy is verified by comparing the predicted results with existing test data. Based on the experimental data of rotating plates, a new rotational force model for quasi-steady theory, which can be applied to a wider scope, is proposed to calculate the trajectory of plate-like windborne debris. The results show that the new model provides a better match with the tested trajectories than previous quasi-steady theories.

Design of Gas Identification System with Hierarchically Identifiable Rule base using GAS and Rough Sets (유전알고리즘과 러프집합을 이용한 계층적 식별 규칙을 갖는 가스 식별 시스템의 설계)

  • Haibo, Zhao;Bang, Young-Keun;Lee, Chul-Heui
    • Journal of Industrial Technology
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    • v.31 no.B
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    • pp.37-43
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    • 2011
  • In pattern analysis, dimensionality reduction and reasonable identification rule generation are very important parts. This paper performed effectively the dimensionality reduction by grouping the sensors of which the measured patterns are similar each other, where genetic algorithms were used for combination optimization. To identify the gas type, this paper constructed the hierarchically identifiable rule base with two frames by using rough set theory. The first frame is to accept measurement characteristics of each sensor and the other one is to reflect the identification patterns of each group. Thus, the proposed methods was able to accomplish effectively dimensionality reduction as well as accurate gas identification. In simulation, this paper demonstrated the effectiveness of the proposed methods by identifying five types of gases.

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Sound Reduction Index of Interior Door by Aperture Sizes at Door's Bottom (하부틈새 크기에 따른 도어의 음향감쇠계수 분석)

  • Kim, Myung-Jun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.9
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    • pp.834-840
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    • 2010
  • The Sound reduction indices(SRIs) of interior door with 13 different size apertures are measured in acoustic chamber. Also, as a theoretical approach, the SRIs are estimated using Gomperts' theory. In this study, the aperture of interior door is focused on the lower part of door leaf which is well known as a main cause to deteriorate the sound insulation performance of door. The results show that the SRI of door strongly depends on the aperture width and the dip in the measured sound reduction index curve by the resonance effect within aperture is observed at high-frequency. On the whole, the values calculated by theory are in good agreement with the measured values including the position of resonance dip. The average difference between the measured and the calculated values is 0.9 dB for 13 doors with different size aperture in terms of the weighted SRI.

Reduction of Unstressed Prevocalic /u/ in English

  • Hwangbo, Young-Shik
    • Journal of English Language & Literature
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    • v.55 no.6
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    • pp.1139-1161
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    • 2009
  • This paper deals with the reduction of unstressed prevocalic /u/ and the appearance of /w/ which are observed in such words as ambiguity [ˌæm bǝ ˈgju: ǝ ti] - ambiguous [æm ˈbɪ gjǝ wǝs]. This phenomenon is recorded in Merriam-Webster Online Dictionary, Webster's Third New International Dictionary, Unabridged, and the draft revisions of Oxford English Dictionary Online. Since this phenomenon has not been studied in detail up to now, this paper aims 1) to collect the data related to the reduction of unstressed prevocalic /u/, 2) to classify them systematically, and 3) to explain the phenomenon in terms of Optimality Theory. In the course of analysis, Prevocalic Lengthening, which is crucial to the preservation of unstressed prevocalic /u/, is reinterpreted as one of the ways to prevent hiatus (annual /æ nju: ǝl/). /w/-insertion is another way to prevent hiatus (annual /æ njǝ wǝl/). In addition it is argued that prevocalic /u/ behaves differently from prevocalic /i/ due to the difference in the articulators involved.