• Nuclear Engineering and Technology
• /
• v.21 no.3
• /
• pp.193-204
• /
• 1989

This paper develops a new method for reconstructing neutron flux distribution, that is based on the maximum entropy Principle in information theory. The Probability distribution that maximizes the entropy Provides the most unbiased objective Probability distribution within the known partial information. The partial information are the assembly volume-averaged neutron flux, the surface-averaged neutron fluxes and the surface-averaged neutron currents, that are the results of the nodal calculation. The flux distribution on the boundary of a fuel assembly, which is the boundary condition for the neutron diffusion equation, is transformed into the probability distribution in the entropy expression. The most objective boundary flux distribution is deduced using the results of the nodal calculation by the maximum entropy method. This boundary flux distribution is then used as the boundary condition in a procedure of the imbedded heterogeneous assembly calculation to provide detailed flux distribution. The results of the new method applied to several PWR benchmark problem assemblies show that the reconstruction errors are comparable with those of the form function methods in inner region of the assembly while they are relatively large near the boundary of the assembly. The incorporation of the surface-averaged neutron currents in the constraint information (that is not done in the present study) should provide better results.

• Proceedings of the KSME Conference
• /
• 2001.11a
• /
• pp.311-316
• /
• 2001

A failure probability model based on Von-Mises failure criterion and the standard normal probability function is proposed. The effects of varying boundary conditions such as internal fluid pressure, external soil, traffic loads, temperature change and corrosion on failure probability of the buried pipes are systematically investigated. To allow for the uncertainties of the design variables, a reliability analysis technique has been adopted; this also allows calculation of the relative contribution of the random variables and the sensitivity of the failure probability.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.4
• /
• pp.204-213
• /
• 2003

A survey for finding corrosion examples was performed on the underground steel piles buried for 19 years in the area of iron and steel making factory near Young-il bay. A failure probability model, which can be used to check the reliability of the corrosive mechanical element, based on Von-Mises failure criterion and the standard normal probability function is proposed. The effects of varying boundary conditions such as temperature change, soil-friction, internal pressure, earthquake, loading of soil, traffic loads and corrosion on failure probability of the buried steel piles are systematically investigated. To allow for the uncertainties of the design variables, a reliability analysis technique has been adopted; this also allows calculation of the relative contribution of the random variables and the sensitivity of the failure probability.

• The KSFM Journal of Fluid Machinery
• /
• v.16 no.2
• /
• pp.42-47
• /
• 2013

Ship stability prediction is very complex in reality. In this paper, risk based approach is applied to predict the probability of a certified ship, which is effected by the forces of sea especially the wave loading. Safety assessment and risk analysis process are also applied for the probabilistic prediction of ship stability. The survival probability of ships encountering with different waves at sea is calculated by the existed statistics data and risk based models. Finally, ship capsizing probability is calculated according to single degree of freedom(SDF) rolling differential equation and basin erosion theory of nonlinear dynamics. Calculation results show that the survival probabilities of ship excited by the forces of the seas, especially in the beam seas status, can be predicted by the risk based method.

• Journal of Computational Design and Engineering
• /
• v.1 no.4
• /
• pp.266-271
• /
• 2014

The survivability of the naval ship is the capability of a warship to avoid or withstand a hostile environment. The survivability of the naval ship assessed by three categories (susceptibility, vulnerability and recoverability). The magnitude of susceptibility of a warship encountering with threat is dependent upon the attributes of detection equipment and weapon system. In this paper, as a part of a naval ship's survivability analysis, an assessment process model for the ship's susceptibility analysis technique is developed. Naval ship's survivability emphasizing the susceptibility is assessed by the probability of detection, and the probability of hit. Considering the radar cross section (RCS), the assessment procedure for the susceptibility is described. It's emphasizing the simplified calculation model based on the probability density function for probability of hit. Assuming the probability of hit given a both single-hit and multiple-hit, the susceptibility is accessed for a RCS and the hit probability for a rectangular target is applied for a given threat.

• Computers and Concrete
• /
• v.15 no.1
• /
• pp.37-54
• /
• 2015

In general, cracks significantly deteriorate the in-situ performance of concrete members and structures, especially in urban metro tunnels that have been embedded in saturated soft soils. The microcapsule self-healing method is a newly developed healing method for repairing cracked concrete. To investigate the optimal microcapsule parameters that will have the best healing effect in concrete, a 3D analytical probability healing model is proposed; it is based on the microcapsule self-healing method's healing mechanism, and its purpose is to predict the healing efficiency and healing probability of given cracks. The proposed model comprehensively considers the radius and the volume fraction of microcapsules, the expected healing efficiency, the parameters of cracks, the broken ratio and the healing probability. Furthermore, a simplified probability healing model is proposed to facilitate the calculation. Then, a Monte Carlo test is conducted to verify the proposed 3D analytical probability healing model. Finally, the influences of microcapsules' parameters on the healing efficiency and the healing probability of the microcapsule self-healing method are examined in light of the proposed probability model.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.8 no.3
• /
• pp.465-470
• /
• 2013

Dempster-Shafer Evidence Theory is available for multi-sensor data fusion. Basic Probability Assignment is essential for multi-sensor data fusion using Dempster-Shafer Theory. In this paper, we proposed a novel method of BPA calculation with signal assessment. We took notice of the signal that reported from the sensor mote at the time slot. We assessed the variation rate of the reported signal from the terminal. The trend of variation implies significant component of the context. We calculated the variation rate of signal for reveal the relation of the variation and the context. We could reach context inference with BPA that calculated with the variation rate of signal.

• Nuclear Engineering and Technology
• /
• v.44 no.7
• /
• pp.755-766
• /
• 2012

A Binary Decision Diagram (BDD) is a graph-based data structure that calculates an exact top event probability (TEP). It has been a very difficult task to develop an efficient BDD algorithm that can solve a large problem since its memory consumption is very high. Recently, in order to solve a large reliability problem within limited computational resources, Jung presented an efficient method to maintain a small BDD size by a BDD truncation during a BDD calculation. In this paper, it is first identified that Jung's BDD truncation algorithm can be improved for a more practical use. Then, a more efficient truncation algorithm is proposed in this paper, which can generate truncated BDD with smaller size and approximate TEP with smaller truncation error. Empirical results showed this new algorithm uses slightly less running time and slightly more storage usage than Jung's algorithm. It was also found, that designing a truncation algorithm with ideal features for every possible fault tree is very difficult, if not impossible. The so-called ideal features of this paper would be that with the decrease of truncation limits, the size of truncated BDD converges to the size of exact BDD, but should never be larger than exact BDD.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1990.10a
• /
• pp.22-27
• /
• 1990

Since an eigenvalue problem in structural analysis has been recognized as an important process for the assessment of structural strength, it is usually to be carried out the eigenvalue analysis or buckling analysis of structures when the compression behabiour of the member is dorminant. In general, various variables involved in the eigenvalue problem have also shown their variability. So it is natural to apply the probabilistic analysis into such problem. Since the limit state equation for the eigenvalue analysis or buckling reliability analysis is expressed implicitly in terms of random variables involved, the probabilistic finite element method is combined with the conventional reliability method such as MVFOSM and AFOSM for the determination of probability of failure due to buckling. The accuracy of the results obtained by this method is compared with results from the Monte Carlo simulations. Importance sampling method is specially chosen for overcomming the difficulty in a large simulation number needed for appropriate accurate result. From the results of the case study, it is found that the method developed here has shown good performance for the calculation of probability of buckling failure and could be used for checking the safety of the calculation of probability of buckling failure and could be used for checking the safely of frame structure which might be collapsed by either yielding or buckling.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.6 s.171
• /
• pp.183-191
• /
• 2005

Axiomatic design offers a scientific base for design in an efficient way. It is well known that it has two axioms: the Independence Axiom and the Information Axiom. Many applications of the Independence Axiom have been published, however, the Information Axiom has been mainly applied to IFR (functional requirement) - 1DP (design parameter) problems except fer a few case studies. This research presents various methods for calculation of information content. Generally, the information content is evaluated by the probability of success. The probability of success is calculated in two ranges: the FR range and the DP range. In the FR range, the graphical method is utilized with uniform distribution of the DP. In the FP range, the integration method is employed. It is noted that any distribution function of the DP can be accommodated in the integration method. The developed method can be applied to a decoupled design with multiple FRs and DPs. The developed method is extended to a coupled design and a design with a hierarchical structure of axiomatic design.