• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.789-796
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• 2003

A reliability analysis is performed to investigate the influence of the uncertainty from the limited in-situ samples and the inherent heterogeneity of the ground on the probability of piping for the marine embankment near shore. The result are compared with those of the deterministic piping stability analysis performed using the fininte element flow analysis. The random variables used are hydraulic conductivity of the ground subsurface and embankment, and the water level of both internal and external side of the embankment. The probability of piping is most sensitive to the mean and standard deviation of internal water level of the embankment among the random variables included in the reliability analysis. It is found that the lower limits of internal water level which satisfies the allowable proability of piping failure for the embankment studied were E.L(-) 1.83m and E.L(-) 1.48m during and after the construction of the embankment, respectively.

• Journal of Korean Society for Quality Management
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• v.27 no.4
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• pp.114-122
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• 1999

As the rapid growth of Industrial society, many enterprises are inclined to ppm management from the traditional$3\'{o}$ management method. Therefore it is need to extend process capability index for guarantee of quality assurance level to ppm unit. Thus, in this paper, using the probability of standard normal distribution from $ 3\'{o}; to; 6\'{o}$ which was developed by Song(1997), the capability index which is proposed considers the numbers of inspection facility and quality assurance level. Also, quality assurance level is determined by considering the precision of inspection when one and two sided specification limits are given for the probability which is out of the specification limit.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2124-2135
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• 2006

In this paper, the reliability estimation of pipelines is performed by employing the probabilistic method, which accounts for the uncertainties in the load and resistance parameters of the limit state function. The FORM (first order reliability method) and the SORM (second order reliability method) are carried out to estimate the failure probability of pipeline utilizing the FAD (failure assessment diagram). And the reliability of pipeline is assessed by using this failure probability and analyzed in accordance with a target safety level. Furthermore, the MCS (Monte Carlo Simulation) is used to verify the results of the FORM and the SORM. It is noted that the failure probability increases with the increase of dent depth, gouge depth, operating pressure, outside radius, and the decrease of wall thickness. It is found that the FORM utilizing the FAD is a useful and is an efficient method to estimate the failure probability in the reliability assessment of a pipeline. Furthermore, the pipeline safety assessment technique with the deterministic procedure utilizing the FAD only is turned out more conservative than those obtained by using the probability theory together with the FAD. The probabilistic method such as the FORM, the SORM and the MCS can be used by most plant designers regarding the operating condition and design parameters.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.5
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• pp.405-409
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• 2009

Reliability analysis of coastal structure using importance sampling was shown. When Monte Carlo simulation is used to evaluate overturng failure probability of coastal structure, very low failure probability leads to drastic increase in simulation time. However, importance sampling which uses randomly chosen design candidates around the failure surface makes it possible to analyze very low failure probability efficiently. In the numerical example, failure probability of caisson type quay wall was analyzed by using importance sampling and performance according to the level of failure probability was shown.

• Journal of Environmental Science International
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• v.17 no.1
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• pp.57-66
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• 2008

The frequency analysis and the probability plot were applied to heavy metal contents of soils collected from the Goseong Cu mine area as a statistic method for the determination of the threshold value which was able to partition a population comprising largely dispersed heavy metal contents into the background and the anomalous populations. Almost all the heavy metal contents of soil showed a positively skewed distributions and their cumulative percentage frequencies plotted as a curved lines on logarithmic probability plot which represent a mixture of two or more overlapping populations. Total Cu, Pb and Cd data and extractable Cu and Pb data could be partitioned into background and anomalous populations by using the inflection in each curve. The others showed a normally distributed population or an largely overlapped populations. The threshold values obtained from replotted frequency distributions with the partitioned populations were Cu 400 mg/kg, Pb 450 mg/kg and Cd 3.5 mg/kg in total contents and Cu 40 mg/kg and Pb 12 mg/kg in extractable contents, respectively. The thresholds for total contents are much higher than the tolerable level of soil pollution proposed by Kloke(Cu 100 mg/kg, Pb 100 mg/kg, Cd 3 mg/kg), but those for extractable contents are not exceeded the worrying level of soil pollution proposed by Ministry of Environment(Cu 50 mg/kg, Pb 100 mg/kg). When the threshold values were used as the criteria of soil pollution in the study area, $9{\sim}19%$ of investigated soil population was in polluted level. The spatial distributions of heavy metal contents greater than threshold values showed that polluted soils with heavy metals are restricted within the mountain soils in the vicinity of abandoned mines.

• Journal of Elementary Mathematics Education in Korea
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• v.21 no.2
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• pp.391-414
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• 2017

The purpose of this study is to find the correlation between the level of 6th graders' achievement level in Probability and Statistics education, which were proposed in the curriculum, which targeted the 6th graders in the elementary school, and statistical literacy. For this, first, questions asking the achievement level in the probability and statistics(Part A), and questions asking the statistical literacy(Part B), were used to study the achievement level of the students. Second, the achievement level in the probability and statistics, and the statistical literacy were measured. In order to achieve the purpose of this study, questionnaire that consists of 10 questions was invented. The questionnaire was divided into Part 1 and Part 2 under the consideration upon the characteristics of the questions. The results of the questionnaires given to the students were classified into "high, medium, and low" and were separated into 7 categories. Results of comparing category 3 and category 6, which have shown opposing tendencies, we could find that students who are good at school mathematics and students with high statistical literacy have respective and different characteristics. For actually effective statistical education, consideration upon and reflection of core aspects such as intuition and critical thinking in the curriculum are needed.

• International Journal of Human Ecology
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• v.6 no.2
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• pp.63-72
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• 2005

This paper considered the impact of changing the product liability rule from consumer to producer liability on product safety under asymmetric information. In particular, it has been attempted to remove several constraints on antecedent studies. The main results of the study are as follows: under the misperception of the risk on a product, consumers may underestimate the probability of product failure. In this case, the accident rate can be lowered under the producer's liability rule. However, even under the asymmetric information, a consumer's estimation on the probability may be converged with the expected risk level, which could be called the 'rational expectation.' In this situation the probability of product failure can be lowered under the strict liability with contributory negligence. Additionally, it is possible to reduce the probability of product failure when a legal rule that imposes liability on cheapest cost avoider is admitted.

• Journal of Navigation and Port Research
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• v.35 no.9
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• pp.729-733
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• 2011

The maritime risk assessment is important not only to evaluate the safety level of the ports and waterways but also to reduce potential maritime accidents at sea in terms of the proactive measures of the maritime accidents. In this paper, the collision risk assessment in Mokpo waterways has been carried out based on the IALA recommended model, IWRAP. To evaluate the accident probabilities in Mokpo waterways, all data of vessels were collected from AIS and Radar observations data and the computer simulations were carried out. To assess the risk on the traffic, the scenario-base approach has been applied to the Mokpo waterway by using the maritime accident statics over the past 5 years.

• Geomechanics and Engineering
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• v.7 no.5
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• pp.539-552
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• 2014

A simplified probability-based design charts for stone column-improved ground have been presented based on the unit cell approach. The undrained cohesion ($c_u$) and coefficient of radial consolidation ($c_r$) of the soft soil are taken as the most predominant random variables. The design charts are developed to estimate the diameter of the stone column or the spacing between the stone columns by employing a factored design value of $c_r$ and $c_u$ so as to satisfy a specific probability level of the target degree of consolidation and/or a target safe load that needs to be achieved in a specified timeframe. The design charts can be used by the practicing engineers to design the stone column-improved ground by considering consolidation and /or bearing capacity of the improved ground.

• Computers and Concrete
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• v.10 no.5
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• pp.507-521
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• 2012

The capacity design of shear forces is one of the special demands of EC8 by which the ductile behavior of structures is implemented. The aim of capacity design is the formation of plastic hinges without shear failure of the elements. This is achieved by deriving the design shear forces from equilibrium conditions, assuming that plastic hinges, with their possible over-strengths, have been formed in the adjacent joints of the elements. In this equilibrium situation, the parameters (dimensions, material properties, axial forces etc) are random variables. Therefore, the capacity design of shear forces is associated with a probability of non-compliance (probability of failure). In the present study the probability of non-compliance of the shear capacity design in columns is calculated by assuming the basic variables as random variables. Parameters affecting this probability are examined and a modification of the capacity design is proposed, in order to achieve uniformity of the safety level.