• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.137-140
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• 2003

This study presents a mathematical model for simulating the fate and transport of a reactive organic contaminant degraded through cometabolism in dual-porosity soils during the in situ bioaugmentations. To investigate the effect of dual-porosity on transport and biodegradation of organic hydrocarbons, a bimodal approach was incorporated into the model. Modified Monod kinetics and a microcolony concept [Molz et at., 1986〕 were employed to represent the effects of biodegrading microbes on the transport and biodegradation of an organic contaminant. The effect of permeability reduction due to biomass accumulation on the flow field were examined in the simulation of a hypothetical field-scale in situ bioaugmentation. Simulation results indicate that the presence of the immobile region can decrease the bioavailablity of biodegradable contaminants and that the placement of microbes and nutrients injection wells should be considered for an effective in situ bioaugmentation scheme.

• 신재생에너지
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• 제2권4호
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• pp.19-26
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• 2006

Tower shell design is very important because tower takes about 20% of overall wind turbine cost. This paper contains procedure of tower analysis and tower shell thickness optimization concept. Some of requirements like eigenfrequency and buckling evaluated by numerical method. But strength and fatigue can be derived by mathematical method simply. Using this procedure, tower shell thickness can be designed without repetition of complicated calculation.

• Kyungpook Mathematical Journal
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• 제52권1호
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• pp.91-97
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• 2012

Let $R$ be a commutative semiring. We define a proper ideal $I$ of $R$ to be 2-absorbing (resp., weakly 2-absorbing) if $abc{\in}I$ (resp., $0{\neq}abc{\in}I$) implies $ab{\in}I$ or $ac{\in}I$ or $bc{\in}I$. We show that a weakly 2-absorbing ideal $I$ with $I^3{\neq}0$ is 2-absorbing. We give a number of results concerning 2-absorbing and weakly 2-absorbing ideals and examples of weakly 2-absorbing ideals. Finally we de ne the concept of 0 - (1-, 2-, 3-)2-absorbing ideals of $R$ and study the relationship among these classes of ideals of $R$.

• 공학교육연구
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• 제6권1호
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• pp.32-41
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• 2003

본 논문에서는 자바 애플릿을 이용하여 웹 기반의 미분방정식 학습용 컨텐츠를 개발하였다. 컴퓨터 분야의 컴포넌트 기반의 소프트웨어 개발기법을 도입하여, 사용하기에 단순하고 편리한 자바 빈즈 컴포넌트를 먼저 개발하고, 이를 활용하여 미분방정식 학습용 컨텐츠를 개발하였다. 개발된 컨텐츠는 높은 상호작용 기능을 가지고 있어서, 학습자가 흥미를 갖고 학습할 수 있고, 풀이 절차를 반복적으로 확인할 수 있으며, 복잡한 수학적 개념을 쉽게 이해할 수 있다.

• 한국수학사학회지
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• 제30권5호
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• pp.289-304
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• 2017

The interdisciplinary study explores the discussion of actual infinity between Georg Cantor and Roman Catholic Church. Regarding the actual infinity, we first trace the theological background of Cantor by interpreting his correspondence and major works including ${\ddot{U}}ber$ die verschiedenen Standpunkte in bezug auf das aktuelle Unendliche(1885) and Mitteilungen zur Lehre vom Transfiniten (1887), and then investigate his argumentation for two points at issue: (1) pantheism and (2) inconsistency of the necessity with freedom of God. In terms of mathematics and theology, Cantor defined the actual infinity(aphorismenon) as characterized by (1) the transfinite infinity(Transfinitum) and (2) the absolute infinity(Absolutum). Transfinitum is conceptualized here in mathematical terms as a multipliable actual infinity, whereas Absolutum is not as a multipliable actual infinity. The results imply that Cantor's own concept of Transfinitum and Absolutum is adequate for Roman Catholic theology as well as mathematics including the reflection principle.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제6권1호
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• pp.39-45
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• 1999

The concept of pseudoLindelof spaces is introduced. It is shown that the followings are equivalent: (a) for any two disjoint zero-sets in X, at least one of them is Lindelof, (b) $\mid$vX{\;}-{\;}X$\mid${\leq}{\;}1$, and (c) for any space T with $X{\;}{\subseteq}{\;}T$, there is an embedding $f{\;}:{\;}vX{\;}{\rightarrow}{\;}vT$ such that f(x) = x for all $x{\;}{\in}{\;}X$ and that if $X{\;}{\times}{\;}Y$ is a z-embedded pseudoLindelof subspace of $vX{\;}{\times}{\;}vY,{\;}then{\;}v(X{\;}{\times}{\;}Y){\;}={\;}vX{\;}{\times}{\;}vY$.

• 산업경영시스템학회지
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• 제13권21호
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• pp.29-41
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• 1990

An assessment of risk in industrial and urban environments is essential in the prevention of accident and in the analysis of situations which are hazardous to public health and safety. The risk imposed by a particular hazard increases with the likelihood of occurence of the event, the exposure and the possible consequence of that event. In a traditional approach, the calculation of a quantitative value of risk is usually based on an assignment of numerical values of each of the risk factors. Then the product of the values of likelihood, exposure and consequences called risk score is derived. However vagueness and imprecision in mathematical quantification of risk are equated with fuzziness rather than randomness. In this paper, a fuzzy set theoretic approach to risk analysis is proposed as an alternative to the techniques currently used in the area of systems safety. Then the concept of risk evaluation using linguistic representation of the likelihood, exposure and consequences is introduced. A risk assessment model using approximate reasoning technique based on fuzzy logic is presented to drive fuzzy values of risk and numerical example for risk analysis is also presented to illustrate the results.

• 동력기계공학회지
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• 제4권1호
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• pp.51-59
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• 2000

Active suspension systems have been using for improving ride quality and stability for vehicles. An active suspension system is composed of a hydraulic pump, pressure control valves, hydraulic dampers, vehicle body, tires and other components. In this study, the mathematical model for the active suspension system based on the quarter car concept is derived, and a program for analysing the dynamic behaviour of the suspension system is developed. The computed results by the developed program are compared with the experimental results for confirming the reliability and usefulness of the developed program.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.571-576
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• 2007

This study presents stiffness-based optimal design to control quantitatively lateral drift of frame-shear wall structures subject to seismic loads. To this end, lateral drift constraints are established by introducing approximation concept that preserves the generality of the mathematical programming and can efficiently solve large scale problems. Also, the relationships of sectional properties are established to reduce the number of design variables and resizing technique of member is developed under the 'constant-shape' assumption. Specifically, the methodology of dynamic displacement sensitivity analysis is developed to formulate the approximated lateral displacement constraints. The 12 story frame-shear wall structural models is considered to illustrate the features of dynamic stiffness-based optimal design technique proposed in this study.

• Kyungpook Mathematical Journal
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• 제47권4호
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• pp.473-480
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• 2007

In this paper we define prime right ideals of semirings and prove that if every right ideal of a semiring R is prime then R is weakly regular. We also prove that if the set of right ideals of R is totally ordered then every right ideal of R is prime if and only if R is right weakly regular. Moreover in this paper we also define prime subsemimodule (generalizing the concept of prime right ideals) of an R-semimodule. We prove that if a subsemimodule K of an R-semimodule M is prime then $A_K(M)$ is also a prime ideal of R.