• 한국농공학회지
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• 제38권5호
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• pp.125-139
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• 1996

This study was performed to provide the design method for soil structure which guarantees proper safety with uncertainty of soil parameters. For this purpose, the effect of uncertainty of soil parameters for slope stability was analyzed by Bishop's simplified method and Monte Carlo simulation(MC). And reliability analysis program, RESFEM, was developed by combining elastic theory, MC, FEM, SFEM, and reliability, which can consider uncertainty of soil parameters. For factor of safety(FS) 1.0 and 1.2 by Bishop's simplified method, the probability of failure(Pf) was analyzed with varying coefficient of variation(c.o.v.) of soil parameters. The Pf increased as c.o.v. of soil parameters increased. This implies that FS is not the absolute index of slope safety, and even if FS is same, it has different Pf according to c.o.v. of soil parameters. The RESFEM was able to express the Pf at each element in slope quantitatively according to uncertainty of soil parameters. The variation of Pf with uncertainty of soil parameters was analyzed by RESFEM, and it was shown that the Pf increased as the c.o.v. of soil parameters increased.

• 한국방재학회 논문집
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• 제2권3호
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• pp.89-99
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• 2002

본 연구에서는 가뭄빈도공식을 이용해서 목포지역의 가뭄을 평가하고자 하였으며, 이를 위해 Sharma(1997)가 제안한 가뭄빈도공식을 이용한 가뭄빈도해석을 실시하였다. 본 연구에서 적용된 가뭄빈도공식은 빈도계수법 형태인 연강수량 자료계열을 이용하였으며, 5년 가뭄빈도보다 큰 가뭄을 가뭄년으로 선정하고, 대상지역에 대한 과거 가뭄을 평가하였다. 이를 통해 목포지역의 가장 큰 가뭄은 1995년에 발생하였으며, 그 해의 연강수량은 613.2mm로서 30년 가뭄빈도에 해당됨을 알 수 있었다.

• International Journal of Contents
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• 제2권2호
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• pp.17-24
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• 2006

The work presented in this paper is divided into two parts. The first part presents finite urn problems which generate truncated negative binomial random variables. Some combinatorial identities that arose from the negative binomial sampling and truncated negative binomial sampling are established. These identities are constructed and serve important roles when we deal with these distributions and their characteristics. Other important results including cumulants and moments of the distributions are given in somewhat simple forms. Second, the distributions of the maximum of two chi-square variables and the distributions of the maximum correlated F-variables are then derived within the negative binomial sampling scheme. Although multinomial theory applied to order statistics and standard transformation techniques can be used to derive these distributions, the negative binomial sampling approach provides more information and deeper insight regarding the nature of the relationship between the sampling vehicle and the probability distributions of these functions of chi-square variables. We also provide an algorithm to compute the percentage points of these distributions. We supplement our findings with exact simple computational methods where no interpolations are involved.

• International Journal of Contents
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• 제3권1호
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• pp.1-8
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• 2007

The distributions of the minimum correlated F-variable arises in many applied statistical problems including simultaneous analysis of variance (SANOVA), equality of variance, selection and ranking populations, and reliability analysis. In this paper, negative binomial sampling technique is employed to derive the distributions of the minimum of chi-square variables and hence the distributions of the minimum correlated F-variables. The work presented in this paper is divided in two parts. The first part is devoted to develop some combinatorial identities arised from the negative binomial sampling. These identities are constructed and justified to serve important purpose, when we deal with these distributions or their characteristics. Other important results including cumulants and moments of these distributions are also given in somewhat simple forms. Second, the distributions of minimum, chisquare variable and hence the distribution of the minimum correlated F-variables are then derived within the negative binomial sampling framework. Although, multinomial theory applied to order statistics and standard transformation techniques can be used to derive these distributions, the negative binomial sampling approach provides more information regarding the nature of the relationship between the sampling vehicle and the probability distributions of these functions of chi-square variables. We also provide an algorithm to compute the percentage points of the distributions. The computation methods we adopted are exact and no interpolations are involved.

• 조명전기설비학회논문지
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• 제29권6호
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• pp.35-41
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• 2015

This paper presents a breakdown voltage and a process of breakdown progress in mineral oil under an quasi-uniform field with decomposition products which occur after the oil discharge. The breakdown voltage in the oil revealed the characteristics of dispersion regardless of an electrode gap. The cumulative probability distribution was used to analyze the dispersion of the breakdown voltage. In addition, the process of breakdown progress in the oil can be reasonably described by the electron breakdown theory based on both electrons emitted from the cathode and ions by field-aided dissociation of the oil. The proposed breakdown process will be used for the basic data to explain the behavior pattern of the decomposition product to cause the dispersion of the breakdown voltage.

• 설비공학논문집
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• 제11권4호
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• pp.511-517
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• 1999

Determining the simultaneous flow rate in any particular section of piping is the important step in order to determine the size of water supply piping. Now we are using the diversity curve of common water closet in order to determine the simultaneous flow rate of water supply piping, but there is a difference between a determined flow rate of general water closet and that of water closet for water saving. This study aims to find out the fixture unit of a flush valve type water closet for water saving in office building, and to determine the correlation between the fixture units and peak flow rates on the basis of the probability theory. A flush valve type water closet for water saving that have a 7.5 second duration of flush operation with an average design flow rate 72 $\ell$/fin was considered. Simulation results indicate that the number 5 is shown to be reasonable to the fixture unit of water closet for water saving. And the design can be undersized considerably with the revised diversity curves using modified fixture unit.

• 한국지진공학회논문집
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• 제6권5호
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• pp.29-36
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• 2002

교량의 내진성능확보를 위한 유지보수계획을 수립하는데 있어서, 전체 생애주기비용의 최소화를 통하여 최적의 검사 및 수리회수의 결정방법을 제시한다. 생애주기 비용에는 초기비용, 파괴비용 뿐만 아니라, 검사 및 보수비용이 포함된다. 시간에 따른 내진성능저하모델을 손상함수를 이용하여 표현하였으며, 손상감지정도에 따른 Event Tree Analysis를 통하여 유지보수에 따른 파괴확률을 랜덤진동이론을 이용하여 산출한다. 예제로서 10경간 연속교의 최적유지보수방법을 살펴본 결과, 가속도계수가 증가하고, 연약지반일수록 최적유지보수회수는 증가하는 것으로 나타났다.

• Wind and Structures
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• 제20권2호
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• pp.169-189
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• 2015

To investigate the effects of "sudden change" of wind fluctuations on vehicle running performance, which is caused by the artificial discrete simulation of wind field, a three-dimensional vehicle model is set up with multi-body dynamics theory and the vehicle dynamic responses in crosswind conditions are obtained in time domain. Based on Hilbert Huang Transform, the effects of simulation separations on time-frequency characteristics of wind field are discussed. In addition, the probability density distribution of "sudden change" of wind fluctuations is displayed, addressing the effects of simulation separation, mean wind speed and vehicle speed on the "sudden change" of wind fluctuations. The "sudden change" of vehicle dynamic responses, which is due to the discontinuity of wind fluctuations on moving vehicle, is also analyzed. With Principal Component Analysis, the comprehensive evaluation of vehicle running performance in crosswind conditions at different simulation separations of wind field is investigated. The results demonstrate that the artificial discrete simulation of wind field often causes "sudden change" in the wind fluctuations and the corresponding vehicle dynamic responses are noticeably affected. It provides a theoretical foundation for the choice of a suitable simulation separation of wind field in engineering application.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.275-276
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• 2009

본 논문에서는 중성화에 노출된 콘크리트 구조불의 내구성을 예측하기 위한 새로운 접근 방법을 제시한다. 이 예측 방법은, 새로운 계측 데이터 있을 때 베이스 이론에 근거하여 지속적으로 업데이팅 을 할 수 있다. 모델 매개변수의 확률론적인 특성이 고려된다. 염해 해석 모델의 절차는 라틴 하이퍼 큐브 샘플 추출법으로 간단하게 정리되고 이를 통해 얻는 표본으로 결정된다. 이러한 새로운 방법은 중요한 콘크리트 구조물을 설계하기에 아주 유용하고 모니터링을 통한 실 콘크리트 구조물의 잔존수명을 예측 할 수 있다.

• 한국인터넷방송통신학회논문지
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• 제14권6호
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• pp.47-54
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• 2014

러프집합을 구성하는 식별불가능 관계를 표현하는 정보시스템에서 데이터의 중복이나 비일관성은 피할 수 없기 때문에 속성의 감축은 매우 중요하다. 러프집합이론에 있어서 일관적인 정보시스템과 비일관적인 정보시스템의 속성감축의 차이를 극복하고 자, 본 연구에서는 조건 및 결정속성에 대한 상관분석에 베이지언 사후확률을 적용한 새로운 불확실성 척도와 속성감축 알고리즘을 제안한다. 정보시스템의 불확실성에 대하여 제안된 척도와 기존의 조건부 정보엔트로피 척도를 비교해 본 결과, 정보시스템의 조건속성과 결정속성의 상호정보를 이용하여 속성간의 불확실성을 측정하는데 있어 제안된 방법이 조건부 정보엔트로피에 의한 방법보다 정확성이 있음을 보여준다.