• Journal of the Korean Data and Information Science Society
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• 제11권2호
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• pp.269-277
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• 2000

독립이면서 로그정규분포를 따르는 두 모집단의 평균 차이에 대한 검정으로 Berger와 Pericchi(1996, 1998)가 제안한 내재적 베이즈 요인(intrinsic Bayes factor)을 이용한 베이지안 방법을 제안한다. 이 때 모수에 대한 사전분포로는 무정보적 사전분포(noninformative prior)를 사용한다. 제안한 검정 방법의 유용성을 알아보기 위해 실제 자료의 분석과 모의실험을 이용하여 고전적인 검정 방범과 그 결과를 비교한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.101-104
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• 2006

In the past study, the fragility curve for the evaluation of earthquake resistance and earthquake-related damage of concrete bearing wall structures were studied. The fragility curve represents the probability of being in or exceeding a given damage state such as Slight, Moderate, Extensive or Complete structural damage state, and is defined as a cumulative lognormal distribution. Each fragility curve is characterized by median and lognormal standard deviation values. We performed parametric pushover analysis for typical 12 and 24 stories apartment buildings. Based on the results, the fragility curves of concrete wall structures were standardized. Using the fragility curve, engineers can directly evaluate the probability of a damage state to a spectral displacement of interest.

• 대한교통학회지
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• 제26권5호
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• pp.217-226
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• 2008

통행시간 신뢰성은 통행자가 예측하기 힘든 통행시간의 변동을 설명하는 개념이다. 본 연구는 통행시간 신뢰성을 측정할 수 있는 지표를 개발하고, 국내 도로 및 철도 이용 실적자료를 바탕으로 통행시간 신뢰성 지표 원단위를 산정한다. 통행시간 신뢰성 측정 지표로 수정형 완충시간 지표를 제안하며, 신뢰성/비신뢰성의 임계점으로는 로그정규 통행시간분포를 기반으로 한 계획 통행시간과 실제 통행시간의 차이를 측정한다. 이를 통해 철도는 상수형 도로는 음의 포물선형 통행시간 신뢰성 지표함수를 개발한다. 본 연구의 결과가 도로 및 철도 투자사업의 신중한 의사결정에 일조할 수 있기를 기대한다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.319-325
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• 2003

The fragility curves of seismic retrofitted bridges by steel jacketing of bridge columns and restrainers at expansion joints after the 1994 Northridge earthquake are developed. Fragility curves are represented by lognormal distribution functions with two parameters(fragility parameters consisting of median and log-standard deviation) and developed as a function of peak ground acceleration (PGA). Two parameters in the lognormal distribution are estimated by the maximum likelihood method. The sixty ground acceleration time histories for Los Angeles area developed for FEMA SAC project are used for the dynamic analysis of the bridges and a computer code is developed to calculate hysterestic parameters of bridge columns before and after steel jacketing. The effect of retrofit is expressed in terms of the increase of the median value of the fragility curve for the retrofitted bridge from that of the bridge before retrofit. The comparison of fragility curves of the bridges before and after column retrofit demonstrates that the improvement of the bridges with steel jacketing on the seismic performance is excellent for the damage states defined in this study. The comparison of fragility curves of the bridges before and after restrainers at expansion joints also shows the improvement in the seismic performance of restrained bridges for the severe damage states.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.484-497
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• 2021

This paper proposes an extended time uncertainty analysis approach in Level 2 human reliability analysis (HRA) considering severe accident management (SAM) strategies. The method is a time-based model that classifies two time distribution functions-time required and time available-to calculate human failure probabilities from delayed action when implementing SAM strategies. The time required function can be obtained by the combination of four time factors: 1) time for diagnosis and decision by the technical support center (TSC) for a given strategy, 2) time for strategy implementation mainly by the local emergency response organization (ERO), 3) time to verify the effectiveness of the strategy and 4) time for portable equipment transport and installation. This function can vary depending on the given scenario and includes a summation of lognormal distributions and a choice regarding shifting the distribution. The time available function can be obtained via thermal-hydraulic code simulation (MAAP 5.03). The proposed approach was applied to assess SAM strategies that use portable equipment and safety depressurization system valves in a total loss of component cooling water event that could cause reactor vessel failure. The results from the proposed method are more realistic (i.e., not conservative) than other existing methods in evaluating SAM strategies involving the use of portable equipment.

• 한국대기환경학회지
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• 제16권1호
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• pp.1-10
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• 2000

The behavior of aerosos due to gravitational coagulation was studied experimentally and numerically. In experimental study, the geometric mean particel size increased as time elapsed in a vertical tube column, while the size decreased when the tube was set horizontally. The particle size distribution was observed to maintain the lognormal form during the coagulation process. Separately, numerical calculations were performed for studying the aerosol behavior under gravitational and Brownian coagulation using the moment method. By comparing the expeimented results with the numerical predictions, the governing mechanism of the aerosol behavior proved to be gravitational coagulation.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2000년도 추계학술대회
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• pp.299-311
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• 2000

This paper is concerned with the method of estimating lifetime distribution for field data in warranty period and for a situation where some additional field data can be gathered after the warranty period. Implementing the proposed methods in this paper will result in obtaining the more precise product life time estimation and product improvement.

• 한국산업융합학회 논문집
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• 제9권3호
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• pp.207-214
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• 2006

In this paper, the stability of SA(Spectral Acceleration) fragility curves is studied for the two sets of elastic modulus of concrete. In doing that, general purpose structural analysis program and generally used probability density function are used. The results of structural analysis are represented by Bernoulli distribution which says damage or no damage. By the use of Maximum Likelihood Method, two parameters of lognormal distribution - median and standard deviation - are found. With them, the fragility curves are constructed.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.840-849
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• 2013

This paper presents a statistical approach to analyze electrical tree inception voltage, electrical tree breakdown voltage and tree breakdown time of unsaturated polyester resin subjected to AC voltage. The aim of this work was to show that Weibull and lognormal distribution may not be the most suitable distributions for analysis of electrical treeing data. In this paper, an investigation of statistical distributions of electrical tree inception voltage, electrical tree breakdown voltage and breakdown time data was performed on 108 leaf-like specimen samples. Revelations from the test results showed that Johnson SB distribution is the best fit for electrical tree inception voltage and tree breakdown time data while electrical tree breakdown voltage data is best suited with Wakeby distribution. The fitting step was performed by means of Anderson-Darling (AD) Goodness-of-fit test (GOF). Based on the fitting results of tree inception voltage, tree breakdown time and tree breakdown voltage data, Johnson SB and Wakeby exhibit the lowest error value respectively compared to Weibull and lognormal.

• 한국정보전자통신기술학회논문지
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• 제12권4호
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• pp.327-335
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• 2019

본 연구는 5년간의 세탁기 및 화장실 용수의 실측 자료를 기반으로 표본가구의 가구 및 주택, 월 특성들을 나타내는 변수들을 조사하여 위의 두 가지 용수에 대한 수요예측모형을 개발하는 것이다. 그러나 반응변수인 세탁기 및 화장실 용수의 분포를 확인한 결과 양의 왜도, 즉, 왼쪽으로 치우친 형태로 정규분포를 따르지 않기 때문에 다중회귀모형 적용 시 추정치가 편의되는 문제가 있다. 따라서 이에 대한 대안으로 세탁기 및 화장실 용수 수요 예측모형을 와이블 및 대수정규회귀모형으로 가정하고, 3가지 모형을 적용하여 최적모형을 제시하고 이에 대한 해석을 제시하였다. 그 결과 와이블 분포를 가정한 회귀모형이 가장 적합하다고 나타났으며, 이에 대한 각 용수별 예측모형을 제시하고 해석하였다. 그 결과 두 용수 모두 공통적으로 실거주인원이 용수사용에 가장 큰 영향을 주는 인자로 나타났다. 분석결과를 토대로 세탁기 및 화장실 용수의 수요를 예측시 실거주인원에 대한 고려가 필요하다는 점을 시사하며, 예측모형을 통한 관리부서에서 장기적으로 물 수요관리에 대한 정책 수립, 수도 관련 시설 규격 및 기자재 결정 등의 기초자료로 활용 할 수 있을 것이라 판단된다. 추후 연구에서는 1인 가구 등과 같은 실태를 반영한 독립변수들을 고려한 실측연구 등이 필요할 것이다.