• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.1-13
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• 2008

An efficient segregated algorithm for the coupling of velocity and pressure of incompressible fluid flow, called IDEAL Inner Doubly-Iterative Efficient Algorithm for Linked-Equations), has been proposed by the present authors. In the algorithm there exist double inner iterative processes for pressure equation at each iteration level, which almost completely overcome two approximations in SIMPLE algorithm. Thus the coupling between velocity and pressure is fully guaranteed, greatly enhancing the convergence rate and stability of solution process. The performance of the IDEAL algorithm for three-dimensional incompressible fluid flow and heat transfer problems is analyzed and a systemic comparison is made between the algorithm and three other most widely-used algorithms (SIMPLER, SIMPLEC and PISO). It is found that the IDEAL algorithm is the most robust and the most efficient one among the four algorithms compared. This new algorithm is used for the velocity prediction of a new interface capturing method. VOSET, also proposed by the present author. It is found that the combination of VOSET and IDEAL can appreciably enhance both the interface capture accuracy and convergence rate of computations.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년 추계학술대회논문집
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• pp.1-13
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• 2008

An efficient segregated algorithm for the coupling of velocity and pressure of incompressible fluid flow, called IDEAL (Inner Doubly-Iterative Efficient Algorithm for Linked-Equations), has been proposed by the present authors. In the algorithm there exist double inner iterative processes for pressure equation at each iteration level, which almost completely overcome two approximations in SIMPLE algorithm. Thus the coupling between velocity and pressure is fully guaranteed, greatly enhancing the convergence rate and stability of solution process. The performance of the IDEAL algorithm for three-dimensional incompressible fluid flow and heat transfer problems is analyzed and a systemic comparison is made between the algorithm and three other most widely-used algorithms (SIMPLER, SIMPLEC and PISO). It is found that the IDEAL algorithm is the most robust and the most efficient one among the four algorithms compared. This new algorithm is used for the velocity prediction of a new interface capturing method -VOSET, also proposed by the present author. It is found that the combination of VOSET and IDEAL can appreciably enhance both the interface capture accuracy and convergence rate of computations.

• 한국과학교육학회지
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• 제19권1호
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• pp.78-90
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• 1999

본 연구에서는 실험에 포함된 이상조건의 이해를 조사하기 위해 수행되었다. 주요 연구질문은 다음과 같다. (1) 실제 실험 상황에는 어떠한 이상조건이 포함 되어 있다고 생각하는가? (2) 실험에 포함된 이상조건들이 실제 실험에서 얼마나 만족되고 있다고 생각하는가 ? (3) 실험에 포함된 이상조건들이 실험 결과에 얼 마나 영향을 준다고 생각하는가 ? (4) 교사들은 실험에 포함된 이상조건에 대해 일반적으로 어떠한 관점을 가지고 있는가 ? 연구질문 1, 2, 3을 위해서 6개의 설문을 개발하여 총 85명의 고등학생과 과학교사에게 직접 실험과 함께 제시하여 응답하도록 하였으며, 연구질문 4를 위해서 과학교사 42명을 대상으로 4개의 설문을 개발하여 응답하도록 하였다. 응답결과는 연구 질문에 따라 분류되어 요약 제시되었으며, 물리 실험 지도를 위한 시사점 추출을 위해 사용되었다.

• 전기학회논문지
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• 제66권12호
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• pp.1759-1771
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• 2017

In this paper, an improved continuous integral variable structure systems(ICIVSS) with the prescribed control performance is designed for simple regulation controls of uncertain general linear systems. An integral sliding surface with an integral state having a special initial condition is adopted for removing the reaching phase and predetermining the ideal sliding trajectory from a given initial state to the origin in the state space. The ideal sliding dynamics of the integral sliding surface is analytically obtained and the solution of the ideal sliding dynamics can predetermine the ideal sliding trajectory(integral sliding surface) from the given initial state to the origin. Provided that the value of the integral sliding surface is bounded by certain value by means of the continuous input, the norm of the state error to the ideal sliding trajectory is analyzed and obtained in Theorem 1. A corresponding discontinuous control input with the exponential stability is proposed to generate the perfect sliding mode on the every point of the pre-selected sliding surface. For practical applications, the discontinuity of the VSS control input is approximated to be continuous based on the proposed modified fixed boundary layer method. The bounded stability by the continuous input is investigated in Theorem 3. With combining the results of Theorem 1 and Theorem 3, as the prescribed control performance, the pre specification on the error to the ideal sliding trajectory is possible by means of the boundary layer continuous input with the integral sliding surface. The suggested algorithm with the continuous input can provide the effective method to increase the control accuracy within the boundary layer by means of the increase of the $G_1$ gain. Through an illustrative design example and simulation study, the usefulness of the main results is verified.

• Kyungpook Mathematical Journal
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• 제57권4호
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• pp.545-558
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• 2017

In this paper, we introduce generalised quasi-ideals in ordered ternary semigroups. Also, we define ordered m-right ideals, ordered (p, q)-lateral ideals and ordered n-left ideals in ordered ternary semigroups and studied the relation between them. Some intersection properties of ordered (m,(p, q), n)-quasi ideals are examined. We also characterize these notions in terms of minimal ordered (m,(p, q), n)-quasi-ideals in ordered ternary semigroups. Moreover, m-right simple, (p, q)-lateral simple, n-left simple, and (m,(p, q), n)-quasi simple ordered ternary semigroups are defined and some properties of them are studied.

• 대한수학회보
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• 제31권2호
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• pp.167-172
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• 1994

For a given $C^{*}$-dynamical system (A, G, .alpha.) with a G-simple $C^{*}$-algebra A (that is A has no proper .alpha.-invariant ideal) many authors have studied the simplicity of a $C^{*}$-crossed product A $x_{\alpha{r}}$ G. In [1] topological freeness of an action is shown to guarantee the simplicity of the reduced $C^{*}$-crossed product A $x_{\alpha{r}}$ G when A is G-simple. In this paper we investigate the pure infiniteness of a simple $C^{*}$-crossed product A $x_{\alpha}$ G of a purely infinite simple $C^{*}$-algebra A and a topologically free action .alpha. of a finite group G, and find a sufficient condition in terms of the action on the spectrum of the multiplier algebra M(A) of A. Showing this we also prove that some extension of a topologically free action is still topologically free.

• 한국과학교육학회지
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• 제19권1호
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• pp.62-77
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• 1999

이상화는 물리학 연구뿐 아니라 물리학을 배우는 학습 과정에서도 중요한 역할을 한다. 본 연구에서는 역학과 전기, 그리고 열역학 영역에서 문제 해결 과정과 현상의 설명 과정에는 어떠한 이상 조건이 포함되어 있다고 생각하는지에 대해 일반계 고등학생과 과학고 학생, 그리고 과학 교사를 대상으로 조사하였다. 조사 결과, 과학교육학자들이 예상했던 것과는 달리 많은 학생들이 다양한 종류의 이상 조건들을 잘 언급하였음을 알 수 있었다. 물론, 이상 조건과 일반적 조건을 구분하지 못하거나 현상을 그대로 기술하거나 법칙을 언급하는 것으로 이상 조건을 대신하기도 하였다. 특히, 이상 조건에 대한 생각에서 여러 가지 오개념이 발견되어 이상 조건에 대한 연구와 오개념 연구가 연관성을 가질 수 있음을 발견하였다.

• 대한수학회지
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• 제54권3호
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• pp.847-865
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• 2017

For a finite or an infinite set X, let $2^X$ be the power set of X. A class of simple graph, called strong Boolean graph, is defined on the vertex set $2^X{\setminus}\{X,{\emptyset}\}$, with M adjacent to N if $M{\cap}N={\emptyset}$. In this paper, we characterize the annihilating-ideal graphs $\mathbb{AG}(R)$ that are blow-ups of strong Boolean graphs, complemented graphs and preatomic graphs respectively. In particular, for a commutative ring R such that AG(R) has a maximum clique S with $3{\leq}{\mid}V(S){\mid}{\leq}{\infty}$, we prove that $\mathbb{AG}(R)$ is a blow-up of a strong Boolean graph if and only if it is a complemented graph, if and only if R is a reduced ring. If assume further that R is decomposable, then we prove that $\mathbb{AG}(R)$ is a blow-up of a strong Boolean graph if and only if it is a blow-up of a pre-atomic graph. We also study the clique number and chromatic number of the graph $\mathbb{AG}(R)$.

• East Asian mathematical journal
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• 제30권5호
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• pp.617-623
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• 2014

Due to Bell, a ring R is usually said to be IFP if ab = 0 implies aRb = 0 for $a,b{\in}R$. It is shown that if f(x)g(x) = 0 for $f(x)=a_0+a_1x$ and $g(x)=b_0+{\cdots}+b_nx^n$ in R[x], then $(f(x)R[x])^{2n+2}g(x)=0$. Motivated by this results, we study the structure of the IFP when proper ideals are taken in place of R, introducing the concept of insertion-of-ideal-factors-property (simply, IIFP) as a generalization of the IFP. A ring R will be called an IIFP ring if ab = 0 (for $a,b{\in}R$) implies aIb = 0 for some proper nonzero ideal I of R, where R is assumed to be non-simple. We in this note study the basic structure of IIFP rings.

• Journal of applied mathematics & informatics
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• 제41권5호
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• pp.1037-1046
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• 2023

The reason behind to investigate axiom systems with fewer axioms into investigate what types of results still hold, and what results become more general. Seminearrings obtained by the generalisation of nearrings and semirings. Clearly, seminearrings are common abstraction of semirings and nearrings. The aim of this work is to carry out an extensive study on algebraic structure of seminearrings and the major objective is to further enhance the theory of seminearrings in order to study the special structures of seminearrings, this work addresses some special structures of seminearrings such as right duo seminearrings. The right ideal of a seminearring need not be a left ideal. We focused on those seminear-rings which demonstrate this property. A seminearring S is right duo if every right ideal is two sided. Here we have concentrated on the seminearring which are right duo and regular. Main aim of this paper is to deal with properties of regularity in right duo seminearring. We have given some results on right duo seminearring. Followed by that, we have derived some theorems on the relation between the properties of seminearring such as regularity, semi simplicity and intra-regularity in right duo seminearring. We also illustrate this concept with suitable examples.