• 한국ITS학회:학술대회논문집
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• 한국ITS학회 2003년도 제2회 정기총회 및 추계학술대회
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• pp.324-329
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• 2003

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2003년도 추계학술발표대회 요약집
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• pp.55.1-55.1
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• 2003

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.779-789
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• 2012

In the kinetic theory of dense fluids the many-particle collision bracket integral is given in terms of a classical collision operator defined in the phase space. To find an algorithm to compute the collision bracket integrals, we revisit the eigenvalue problem of the Liouville operator and re-examine the method previously reported [Chem. Phys. 1977, 20, 93]. Then we apply the notion and concept of the eigenfunctions of the Liouville operator and knowledge acquired in the study of the eigenfunctions to cast collision bracket integrals into more convenient and suitable forms for numerical simulations. One of the alternative forms is given in the form of time correlation function. This form, on a further manipulation, assumes a form reminiscent of the Chapman- Enskog collision bracket integrals, but for dense gases and liquids as well as solids. In the dilute gas limit it would give rise precisely to the Chapman-Enskog collision bracket integrals for two-particle collision. The alternative forms obtained are more readily amenable to numerical simulation methods than the collision bracket integrals expressed in terms of a classical collision operator, which requires solution of classical Lippmann-Schwinger integral equations. This way, the aforementioned kinetic theory of dense fluids is made fully accessible by numerical computation/simulation methods, and the transport coefficients thereof are made computationally as accessible as those in the linear response theory.

• Nuclear Engineering and Technology
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• 제24권3호
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• pp.319-328
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• 1992

일차원 구에서 유한요소법의 Galerkin formulation이 일차형태의 단일 에너지 중성자 수송방정식의 적분법에 적용되었다. 구분적으로 1차 혹은 2차인 Lagrange 다항식들이 선형대수 방정식들의 집합을 만들기 위해 적분법에 있는 각의존 중성자속(angular flux)에 대하여 활용되었다. 수치해석이 균질구에서의 임계문제와 비균질구에서의 scalar flux 분포에 대해서 행해졌다. 공간과 각에 대하여 연속적인 유한요소를 사용한 균질구에서의 임계문제에 대한 유한요소법의 결과들은 이론적인 해들자 비교되었다. 비균질 문제에서는 각자 공간에 대하여 불연속 유한요소를 사용하여 구한 scalar flux 분포는 ANISN code에 의한 계산결과와 잘 일치하였다.

• International Journal of Computer Science & Network Security
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• 제22권7호
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• pp.109-116
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• 2022

The article is devoted to perfecting the system of management of the financial potential of transport enterprises. It is established that transport as an integral part of the state economy has to organically enter the market economy and provide sustainable transport services to national economy enterprises regardless of ownership, as well as ensure passenger transportation. It is also determined that in the conditions of market relations, transport highways must perform their functions with sufficient economic benefit to keep their material and technical resources in good order, conduct an investment policy with extensive use of scientific and technological progress, as well as a social policy guaranteeing the conditions for employees' motivated work. The study reveals an association between the financial and strategic goals of transport enterprises and the minimization of their economic risks, the prevention of bankruptcy and profit margin shortfalls. It is found that transport enterprises need to strive for the overall improvement of their financial potential through increasing the components of financial potential and assessing the impact of risk factors on them: the capacity of fixed assets, the capacity of financial resources, the capacity of services, and the capacity of credit opportunities. These are the elements of transport enterprises' financial potential that ensure its desired level. It is demonstrated that of critical importance in managing the financial potential of a transport enterprise is the role of financial resources, as a subject cannot reach the desired strategic goals without them.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1999년도 춘계종합학술대회
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• pp.394-397
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• 1999

임팩트이온화는 고전계하에서 고에너지를 지닌 캐리어간 산란으로써 전자전송해석에 필수적인 요소이다. 그러나 포물선 또는 비포물선 E-k관계는 고에너지에서 실제 밴드구조와 매우 상이한 결과를 나타내므로 임팩트이온화에 대한 정화한 모델은 풀밴드 E-k관계와 페르미의 황금법칙을 이용하여 제시하고 있다. 본 연구에서는 풀밴드를 이용하여 실리콘 임팩트이온화율에 영향을 미치는 상태밀도와 에너지밴드구조 관계, overlap integral의 에너지에 대한 변화를 조사 분석하였다. 실리콘의 에너지밴드구조를 구하기 위하여 경험적 의사포텐셜방법을 사용하였으며 상태밀도를 구하기 위하여 사면체방법을 사용하였다. 또한 임팩트이온화율을 구하기 위하여 페르미의 황금법칙들 사용하였다. 결과적으로 상태밀도는 에너지증가에 따라 단조 증가하는 임팩트이온화율과 달리 에너지밴드구조에 따라 변화하였다. 그러나 overlap integral은 에너지증가에 따라 큰 값을 갖는 분포가 증가함으로써 임팩트이온화율에 직접 영향을 미치는 것을 알 수 있었다.

• Nuclear Engineering and Technology
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• 제53권7호
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• pp.2221-2228
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• 2021

One-dimensional oxygen transport relation is indispensable to study the oxygen distribution in the LBE-cooled system with an oxygen control device. In this paper, a numerical research is carried out to study the oxygen transport characteristics in a gas-phase oxygen control device, including the static case and dynamic case. The model of static oxygen control is based on the two-phase VOF model and the results agree well with the theoretical expectation. The model of dynamic oxygen control is simplified and the gas-liquid interface is treated as a free surface boundary with a constant oxygen concentration. The influences of the inlet and interface oxygen concentration, mass flow rate, temperature, and the inlet pipe location on the mass transfer characteristics are discussed. Based on the results, an oxygen mass transport relation considering the temperature dependence and velocity dependence separately is obtained. The relation can be used in a one-dimensional system analysis code to predict the oxygen provided by the oxygen control device, which is an important part of the integral oxygen mass transfer models.

• Environmental Engineering Research
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• 제12권4호
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• pp.176-193
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• 2007

The ability to measure groundwater contaminant flux is increasingly being recognized as crucial in order to prioritize contaminated site cleanups, estimate the efficiency of remediation technologies, measure rates of natural attenuation, and apply proper source terms to model groundwater contaminant transport. Recently, a number of methods have been developed and subsequently applied to measure contaminant mass flux in groundwater in the field. Flux measurement methods can be categorized as either point methods or integral methods. As the name suggests, point methods measure flux at a specific point or points in the subsurface. To increase confidence in the accuracy of the measurement, it is necessary to increase the number of points (and therefore, the cost) of the sampling network. Integral methods avoid this disadvantage by using pumping wells to interrogate large volumes of the subsurface. Unfortunately, integral methods are expensive because they require that large volumes of contaminated water be extracted and managed. Recent work has investigated the development of an integral method that does not require extraction of contaminated water from the subsurface. We begin with a review of the significance and importance of measuring groundwater contaminant mass flux. We then review groundwater contaminant flux measurement methods that are either currently in use or under development. Finally, we conclude with a qualitative comparison of the various flux measurement methods.

• 한국전산유체공학회지
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• 제3권1호
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• pp.11-21
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• 1998

A vorticity-based method for the numerical solution of the two-dimensional incompressible Navier-Stokes equations is presented. The governing equations for vorticity, velocity and pressure variables are expressed in an integro-differential form. The global coupling between the vorticity and the pressure boundary conditions is fully considered in an iterative procedure when numerical schemes are employed. The finite volume method of the second order TVD scheme is implemented to integrate the vorticity transport equation with the dynamic vorticity boundary condition. The velocity field is obtained by using the Biot-Savart integral. The Green's scalar identity is used to solve the total pressure in an integral approach similar to the surface panel methods which have been well established for potential flow analysis. The present formulation is validated by comparison with data from the literature for the two-dimensional cavity flow driven by shear in a square cavity. We take two types of the cavity now: (ⅰ) driven by non-uniform shear on top lid and body forces for which the exact solution exists, and (ⅱ) driven only by uniform shear (of the classical type).

• 대한토목학회논문집
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• 제8권3호
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• pp.53-60
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• 1988

가로흐름으로 방류(放流)되는 연직상향평면부력(鉛直上向平面浮力)?의 거동(擧動)이 실험과 기본방정식(基本方程式)의 적분기법(積分技法)에 의하여 해석된다. 적분기법(積分技法)을 상사법칙(相似法則)과 특성(特性)길이를 도입한 연직상향 및 수평방향흐름영역에 대한 점근해(漸近解)이며, 실험은 상이한 속도비와 방류밀도 Froude 수를 변화시키면서 수행되었다. 실험결과(實驗結果)와 해석적해(解析的解)는 잘 일치하여, ?중심선(中心線)의 경로(經路)와 온도(溫度)는 멱법칙(冪法則)으로 표현될 수 있는 것으로 나타났다.