• 산업기술연구
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• 제26권B호
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• pp.83-92
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• 2006

A probabilistic analysis model. one of reliability analysis methods introducing the concept of variables, was developed to investigate the uncertainty of dominant factors influencing the degree of consolidation in the radial consolidation theories. Based on the developed probabilistic analysis model, sensitivity study of those factors was performed to find their trends of affecting the degree of consolidation in the vertical drain method. Various radial consolidation theories, proposed by Barron(1948), Hansbo(1979), Yoshikuni(1979) and Onoue(1988), were used for this parametric study with the influencing factors such as size of smear zone, reduction ratio of permeability in the smear zone, discharge capacity, permeability for horizontal flow and coefficient of consolidation for horizontal flow. As results of this sensitivity study, for the given consolidation theory, contribution of each factor to the degree of consolidation was figure out and compared to each other. For the given value of each factor, the sensitivity to the degree of consolidation in the various theories was evaluated and their applicability and limitations were assessed.

• 한국지반공학회논문집
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• 제29권3호
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• pp.41-50
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• 2013

지반 해석 결과에는 항상 불확실성이 존재하며, 이러한 불확실성은 주로 지반 구조의 불확실한 평가에 기인한다. 이러한 지반 구조의 불확실성에 따른 지반 해석 결과의 불확실성은 몬테카를로 시뮬레이션을 사용한 확률론적 해석에 의해 고려될 수 있다. 몬테카를로 시뮬레이션을 사용한 확률론적 지반 해석의 수행을 위해서는 대상 지반에서 존재 가능한 다양한 지반 구조의 생성이 필요하다. 본 연구에서는 확률론적 지반 해석을 위한 대상 지반에서 존재 가능한 다양한 지반 구조 생성 방법을 제안하였다. 제안된 방법은 대상 지반에서 획득된 지반 조사 결과를 바탕으로 하모닉 웨이브릿 변환을 사용하여 지반 구조를 평가한 후, 이로부터 대상 지반에 존재 가능한 다양한 지반 구조를 생성할 수 있다. 제안된 방법은 실제 현장 조사 결과들에 적용되었으며 이를 통해 제안된 방법의 현장 적용성을 확인할 수 있었다.

• Nuclear Engineering and Technology
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• 제44권5호
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• pp.471-482
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• 2012

To assess the risk of nuclear power plant operation and to determine the risk impact of digital systems, there is a need to quantitatively assess the reliability of the digital systems in a justifiable manner. The Probabilistic Risk Analysis (PRA) is a tool which can reveal shortcomings of the NPP design in general and PRA analysts have not had sufficient guiding principles in modelling particular digital components malfunctions. Currently digital I&C systems are mostly analyzed simply and conventionally in PRA, based on failure mode and effects analysis and fault tree modelling. More dynamic approaches are still in the trial stage and can be difficult to apply in full scale PRA-models. As basic events CPU failures, application software failures and common cause failures (CCF) between identical components are modelled.The primary goal is to model dependencies. However, it is not clear which failure modes or system parts CCF:s should be postulated for. A clear distinction can be made between the treatment of protection and control systems. There is a general consensus that protection systems shall be included in PRA, while control systems can be treated in a limited manner. OECD/NEA CSNI Working Group on Risk Assessment (WGRisk) has set up a task group, called DIGREL, to develop taxonomy of failure modes of digital components for the purposes of PRA. The taxonomy is aimed to be the basis of future modelling and quantification efforts. It will also help to define a structure for data collection and to review PRA studies.

• 대한기계학회논문집A
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• 제26권4호
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• pp.653-659
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• 2002

This paper describes a probabilistic fracture mechanics(PFM) analysis based on Monte Carlo(MC) simulation. In the analysis of CANDU pressure tube, the depth and aspect ratio of an initial semi-elliptical surface crack, a fracture toughness value and delayed hydride cracking(DHC) velocity are assumed to be probabilistic variables. As an example, some failure probabilities of piping and CANDU pressure tube are calculated using MC method with the stratified sampling MC technique, taking analysis conditions of normal operations. In the stratified MC simulation, a sampling space of probabilistic variables is divided into a number of small cells. For the verification of analysis results, a comparison study of the PFM analysis using other commercial code is carried out and a good agreement was observed between those results.

• 대한산업공학회지
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• 제42권4호
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• pp.249-255
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• 2016

Recently, transaction data is accumulated everywhere very rapidly. Association analysis methods are usually applied to analyze transaction data, but the methods have several problems. For example, these methods can only consider one-way relations among items and cannot reflect domain knowledge into analysis process. In order to overcome defect of association analysis methods, we suggest a transaction data analysis method based on probabilistic graphical model (PGM) in this study. The method we suggest has several advantages as compared with association analysis methods. For example, this method has a high flexibility, and can give a solution to various probability problems regarding the transaction data with relationships among items.

• 터널과지하공간
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• 제6권1호
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• pp.30-38
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• 1996

A two dimensional analysis program for groundwater flow in fractured network was developed to analyze the influence of discontinuity characteristics on groundwater flow. This program involves the generation of discontinuities and also connectivity analysis. The discontinuities were generated by the probabilistic density function(P.D.F.) reflecting the characteristics of discontinuities. And the fracture network model was completed through the connectivity analysis. This program also involves the analysis of groundwater flow through the discontinuity network. The result of numerical experiment shows that the equivalent hydraulic conductivity increased and became closer to isotropic as the density and trace length increased. And hydraulic head decreased along the fracture zone because of much water-flow. The grouting increased the groundwater head around cavern. An analysis of groundwater flow through discontinuity network was performed around underground oil storage cavern which is now under construction. The probabilistic density functions(P.D.F) were obtained from the investigation of the discontinuity trace map. When the anisotropic hydraulic conductivity is used, the flow rate into the cavern was below the acceptable value to maintain the hydraulic containment. But when the isotropic hydraulic conductivity is used, the flow rate was above the acceptable value.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.988-992
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• 2011

The buckling characteristics of the continuous welded rail track(CWR) is uncertainly varied by many influence factors, such as rail temperature, operating conditions of a train and maintenance of the track etc. Therefore, applying the probabilistic approach method is essential to rationally consider uncertainty and randomness of the various parameters that affect the track buckling. In this study, the probabilistic approach analysis was carried out and the results were compared with the deterministic approach using the buckling probability evaluation system of CWR tracks developed by our research team. From the comparison, it was identified that a probabilistic approach can quantitatively assess the reliability of the CWR tracks based on failure probability and can be used as a tool for decision making in track design, maintenance and operating etc.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권4호
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• pp.711-725
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• 2013

A heuristic with multi-byte suffix matching plays an important role in real pattern matching algorithms. By skipping many characters at a time in the process of comparing a given pattern with the text, the pattern matching algorithm based on a heuristic with multi-byte suffix matching shows a faster average search time than algorithms based on deterministic finite automata. Based on various experimental results and simulations, the previous works show that the pattern matching algorithms with multi-byte suffix matching performs well. However, there have been limited studies on the mathematical model for analyzing the performance in a standard manner. In this paper, we propose a new probabilistic model, which evaluates the performance of a heuristic with multi-byte suffix matching in an average-case search. When the theoretical analysis results and experimental results were compared, the proposed probabilistic model was found to be sufficient for evaluating the performance of a heuristic with suffix matching in the real pattern matching algorithms.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1211-1215
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• 2003

Pressure tubes are major component of nuclear reactor, but only selected samples are periodically examined due to numerous numbers of tubes. Current in-service inspection result show there is high probability of flaw existence at un-inspected pressure tube. Probabilistic analysis is applied in this study for the integrity assessment of un-inspected pressure tube. But all the current integrity evaluations procedures are based on conventional deterministic approaches. So many integrity evaluation parameters are not directly apply to probabilistic analysis. As a result of this study failure assessment diagram are proposed based on test data.

• 한국방재학회 논문집
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• 제9권2호
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• pp.45-51
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• 2009

지구기후모델을 이용하여 예측된 (1) 물성치와 (2) 현재 및 미래의 표면 에너지 입력상수의 가변성을 고려한 동결 및 융해깊이를 예측하기 위하여 확률론적 접근법이 도입되었다. 확률론적 접근법을 예시하기 위하여 극지방에서의 융해깊이 예측을 고려해보았다. 특히 확률론적 융해깊이 예측을 위하여 몬테카를로 시뮬레이션과 함께 Stefan 공식이 사용되었다. 시뮬레이션 결과는 물성치의 가변성을 보여주었다. 표면 에너지 입력상수와 온도 데이터는 융해깊이를 예측하는데 상당한 불확실성을 야기시킬 수 있다.