• 대한산업공학회지
• /
• 제29권2호
• /
• pp.126-134
• /
• 2003

Among a variety of models proposed by so far to calculate the real options value when the investment decision about the underlying project may be delayed, the Black-Scholes and the binomial lattice models have been widely used and discussed by academics and practitioners. However these two models do not provide us with intuition into how it is constructed and what it does really mean. In this paper, we will therefore explore its components and practically more intuitive meaning. With the components explored, we developed the mathematical model to calculate the real options value and thus strategic net present value, based on the opportunity cost concept, for which the investment decision about the underlying project is postponed by one year. We will finally present a short illustrative example for readers better understanding on the model proposed in the paper.

• 인터넷정보학회논문지
• /
• 제16권3호
• /
• pp.43-57
• /
• 2015

본 논문에서는 개념망을 이용한 효율적인 정보검색을 위한 방법을 제안한다. 본 논문은 일반적인 개념망을 기반으로 시스템을 설계하였기 때문에 온톨로지와 접근 방식은 같지만 사용자가 보다 효율적으로 정보검색을 하고자 하는 객체와 개념사이의 협업 관계를 구축하여 사용할 수 있도록 개념망을 제안한다. 제안한 시스템은 다음과 같다. 첫 번째, 입력 키워드 중심의 키워드 개념망과 전문가 그룹이 추천한 전문가 개념망 그리고 테마 개념망 이러한 세 종류의 개념을 이용하여 협업적 검색을 하며, 이를 기반으로 사용자가 원하는 정보를 검색할 수 있는 효율적인 검색 시스템을 제안한다. 그리고 전문가 개념과 키워드 개념이 결합되어 키워드의 빈도 및 카테고리의 빈도를 제공함으로써, 사용자가 입력한 검색어와 관련된 키워드를 추천하는 역할을 할 수 있다. 그리고 테마 개념망을 이용하여 사용자의 관심 테마에서 사용되는 키워드 또는 카테고리를 알려주는 기능도 제공한다. 두 번째, 사용자가 입력한 키워드가 없을 경우 2차 검색을 통해 입력 키워드와 관련 있는 키워드를 제공해줌으로써 관련키워드를 이용하여 검색의 목적달성이 가능하다. 세 번째, 이러한 정보들은 대부분 분산되어 관리되고 있기 때문에 이렇게 분산되어 관리되는 정보는 표현방식이 다를 뿐만 아니라 시간에 따라 정보가 변하게 된다. 따라서 분산된 정보의 효율적 데이터 접근 및 통합을 위해 XMDR(eXtended Mata-Data Registry)을 이용하였고, 본 논문에서는 분산된 데이터를 통합하기 위한 기법 및 검색 시스템을 제시한다.

• Nuclear Engineering and Technology
• /
• 제42권3호
• /
• pp.271-278
• /
• 2010

While the deterministic lattice physics/depletion codes use leakage-corrected critical spectrum (although approximate due to the B1 buckling search employed), Monte Carlo depletion codes currently in use do not have such a feature in spite of their heterogeneity and continuous-energy modeling capability. This paper describes an approach to Monte Carlo depletion with leakage-corrected critical spectrum derived from first principles. This is based on the concept of albedo eigenvalue treated as weight of the reflected neutron in Monte Carlo simulation.

• Nuclear Engineering and Technology
• /
• 제40권2호
• /
• pp.117-126
• /
• 2008

In this paper, a new reactor core design is proposed on the basis of a mixed core concept consisting of a thermal zone and a fast zone. The geometric structure of the fuel assembly of the thermal zone is similar to that of a conventional thermal supercritical water-cooled reactor(SCWR) core with two fuel pin rows between the moderator channels. In spite of the counter-current flow mode, the co-current flow mode is used to simplify the design of the reactor core and the fuel assembly. The water temperature at the exit of the thermal zone is much lower than the water temperature at the outlet of the pressure vessel. This lower temperature reduces the maximum cladding temperature of the thermal zone. Furthermore, due to the high velocity of the fast zone, a wider lattice can be used in the fuel assembly and the nonuniformity of the local heat transfer can be minimized. This mixed core, which combines the merits of some existing thermal SCWR cores and fast SCWR cores, is proposed for further detailed analysis.

• Nuclear Engineering and Technology
• /
• 제53권3호
• /
• pp.741-751
• /
• 2021

There has been a deep interest in trying to find better-performing fuel clad motivated by the desire to decrease the likelihood of the reactor barrier failure like what happened in Fukushima in recent years. In this study, the effect of move towards accident tolerant fuel (ATF) cladding as the most attracting concept for improving reactor safety is investigated for SMART modular reactor. These reactors have less production cost, short construction time, better safety and higher power density. The SiC and FeCrAl materials are considered as the most potential candidate for ATF cladding, and the results are compared with Zircaloy cladding material from reactor physics point of view. In this paper, the calculations are performed by generating PMAX library by DRAGON lattice physics code to be used for further reactor core analysis by PARCS code. The differential and integral worth of control and safety rods, reactivity coefficient, power and temperature distributions, and boric acid concentration during the cycle are analyzed and compared from the conventional fuel cladding. The rod ejection accident (REA) is also performed to study how the power changed in response to presence of the ATF cladding in the reactor core. The key quantitative finding can be summarized as: 20 ℃ (3%) decrease in average fuel temperature, 33 pcm (3%) increase in integral rod worth and cycle length, 1.26 pcm/℃ (50%) and 1.05 pcm/℃ (16%) increase in reactivity coefficient of fuel and moderator, respectively.