• 천문학회지
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• 제38권2호
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• pp.161-164
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• 2005

We present a theoretical formalism by which the global and the local mass functions of dark matter substructures (dark subhalos) can be analytically estimated. The global subhalo mass function is defined to give the total number density of dark subhalos in the universe as a function of mass, while the local subhalo mass function counts only those sub halos included in one individual host halo. We develop our formalism by modifying the Press-Schechter theory to incorporate the followings: (i) the internal structure of dark halos; (ii) the correlations between the halos and the subhalos; (iii) the subhalo mass-loss effect driven by the tidal forces. We find that the resulting (cumulative) subhalo mass function is close to a power law with the slope of ${\~}$ -1, that the subhalos contribute approximately $10\%$ of the total mass, and that the tidal stripping effect changes the subhalo mass function self-similarly, all consistent with recent numerical detections.

• 한국수학교육학회지시리즈A:수학교육
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• 제52권4호
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• pp.497-516
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• 2013

Inspite of many strengthens of storytelling mathematics education, some problems are expected: when math is taught in concrete contexts, students may have trouble to extract concepts, to transfer to noble and abstract contexts, and they may experience inert knowledge problem. Low achieving students are particularly prone to these issues. To solve these problems some suggestions are made by the author. These are analogous encoding and progressive formalism. Using analogous encoding method students can construct concepts and schema more easily and transfer knowledge which shares structural similarity. Progressive formalism is an effective way of introducing concepts progressively moving from concrete contexts to abstract context.

• 천문학회지
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• 제45권4호
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• pp.101-110
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• 2012

I present here one approach to general relativistic radiation hydrodynamics. It is based on covariant tensor conservation equations and considers only the frequency-integrated total energy and momentum exchange between matter and the radiation field. It is also a mixed-frame formalism in the sense that, the interaction between radiation and matter is described with quantities in the comoving frame in which the interaction is often symmetric in angle while the radiation energy and momentum equations are expressed in the fixed frame quantities in which the derivatives are simpler. Hence, this approach is intuitive enough to be applied straightforwardly to any spacetime or coordinate. A few examples are provided along with caveats in this formalism.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.141-143
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• 2002

In 1995, the American Association of Physicists in Medicine (AAPM) Task Group 43 published a report dealing with the dosimetry of interstitial brachytherapy sources, generally known as the TG-43 report. Compared to previously adopted formalisms, a formalism proposed in this report provides a more accurate and systematic brachytherapy dose calculation method, especially for Ir-192 and other low energy gamma sources such as 1-125 and Pd-l03. In this lecture, an overview of the TG-43 formalism will be presented, along with the lecturer's experience in determining the TG-43 parameters by the Monte Carlo method and experimental methods such as TLD and radiochromic film.

• 한국컴퓨터산업학회논문지
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• 제3권7호
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• pp.891-900
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• 2002

시간 페트리네트는 동시발생적인(concurrent) 시스템을 명세하기 위해 폭 넓게 사용되는 형식론 중의 하나이다. 하지만 시간 페트리네트는 그 형식론 내에서 명확하게 시스템의 역학(dynamics)을 표현하지 못하는 단점을 가지고 있다. 이와 같은 불완전한 형식론은 설계자로 하여금 형식론 자체뿐만 아니라 특정 문제에 의존적인 시뮬레이션 알고리즘까지 고려하게 함으로서 모델링을 매우 어렵게 한다. 이 논문에서는 시스템의 역학을 표현할 수 있는 동적 시간 페트리네트 형식론과 추상적인 시뮬레이터를 제안한다.

• Nuclear Engineering and Technology
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• 제31권1호
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• pp.58-67
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• 1999

The purpose is to produce a model of nuclear reactor trip logic caused by the steam generator water level of Wolsong 2/3/4 unit through an activity chart and a statechart and to produce C language automatically using Statechart-based Formalism and Stalemate MAGNUM toolset suggested by David Harel Formalism. It was worth attempting auto-generation of C language though we manually made Software Requirement Specification(SRS) for safety-critical software using statechart-based formalism. Most of the phases of the software life-cycle except the software requirement specification of an analysis phase were generated automatically by Computer Aided Software Engineering (CASE) tools. It was verified that automatically produced C language has high productivity, portability, and quality through the simulation.

• Journal of Electrical Engineering and information Science
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• 제2권5호
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• pp.100-107
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• 1997

W have developed the simplified formalism of PSBM in order to save calculation time and to increase the accuracy. Using this new formalism of PBM, we have evaluated the loss of the three kinds of waveguide; bent, Y-branch, and cascaded Y-branches. It takes nearly half of the conventional PBM calculation time, even in spite of increasing of he calculation accuracy. This simplified formalism of PBM would be used efficiently in analysis of complicated three dimensional dielectric optical waveguide.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1999년도 추계학술대회논문집
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• pp.35-42
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• 1999

In order to cope with the changes of container terminal situation in these days, many simulation studies for container terminal have been accomplished. But established simulation studies using simulation language have restrictions in model representation and difficulties in modeling of large scaled container terminal system. To make these problems better, in this paper addresses object-oriented simulation of container terminal system using a DEVS formalism. In a step of system modeling, using a DEVS formalism aim at the exact system modeling that has a basis of semantics and utilizing the object-oriented manner can flexibly cope with the changes of system environment. In this study a model was developed and verified through the simulation of some alternatives.

• 한국시뮬레이션학회논문지
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• 제10권3호
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• pp.1-14
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• 2001

A hybrid system is defined as a mixture of continuous systems and discrete event systems. This paper first proposes a framework for hybrid systems modeling, called Hybrid Discrete Event System Specification (HDEVS) formalism. It then presents a method for simulators interoperation in which a continuous system simulator and a discrete event simulator are executed together in a cooperative manner. The formalism can specify a hybrid system in a way that a continuos system and a discrete event system are separately modeled by their own specification formalisms with a support of well-defined interface. We call such interface an A/E converter for analog-to- event conversion and an E/A converter for event-to-analog conversion. Simulators interoperation is based on the concept of pre-simulation in which simulation time for a continuous simulator is advanced in accordance with a discrete event simulator.

• 한국시뮬레이션학회논문지
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• 제1권1호
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• pp.64-76
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• 1992

The DEVS(discrete event system specificaition) formalism specifies a discrete event system in a hierarchical, modular form. DEVSIM++ is a C++based general purpose DEVS abstract simulator which can simulate systems modeled by the DEVS formalism in a sequential environment. This paper describes P-DEVSIM++which is a parallel version of DEVSIM++ . In P-DEVSIM++, the external and internal event of DEVS models can by processed in parallel. For such processing, we propose a parallel, distributed optimistic simulation algorithm based on the Time Warp approach. However, the proposed algorithm localizes the rollback of a model within itself, not possible in the standard Time Warp approach. An advantage of such localization is that the simulation time may be reduced. To evaluate its performance, we simulate a single bus multiprocessor architecture system with an external common memory. Simulation result shows that significant speedup is made possible with our algorithm in a parallel environment.