• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.10 s.103
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• pp.1202-1210
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• 2005

This paper develops a computer model for estimating the bump characterisitcs of a cat)over type large-sized truck. The truck is composed of front and rear suspension systems, a frame, a cab, and ten tires. The computer model is developed using MSC.ADAMS. A shock absorber, a rubber bush, and a leaf spring affect a lot on the dynamic characteristic of the vehicle. Their stiffness and damping coefficient are measured and used as input data of the computer model. Leaf springs in the front and rear suspension systems are modeled by dividing them three links and joining them with joints. To improve the reliability of the developed computer model, the frame is considered as a flexible body. Thus, the frame is modeled by finite elements using MSC.PATRAN. A mode analysis is performed with the frame model using MSC.NASTRAN in order to link the frame model to the computer model. To verify the reliability of the developed computer model, a double wheel bump test is performed with an actual vehicle. In the double wheel bump, vortical displacement, velocity, acceleration are measured. Those test results are compared with the simulation results.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.1983-1989
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• 2020

The human reliability analysis is a method by which, in general terms, the human impact to the safety and risk of a nuclear power plant operation can be modelled, quantified and analysed. It is an indispensable element of the PSA process within the nuclear industry nowadays. The paper herein presents a sensitivity study of the human reliability analysis performed on a real nuclear power plant-specific probabilistic safety assessment model. The analysis is performed on a pre-selected set of post-initiator operator actions. The purpose of the study is to investigate the impact of these operator actions on the plant risk by altering their corresponding human error probabilities in a wide spectrum. The results direct the fact that the future effort should be focused on maintaining the current human reliability level, i.e. not letting it worsen, rather than improving it.

• Journal of Information Processing Systems
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• v.14 no.2
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• pp.377-395
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• 2018

Aiming at the problem of service reliability in resource reservation in cloud computing environments, a model of dynamic cloud resource reservation based on trust is proposed. A domain-specific cloud management architecture is designed in which resources are divided into different management domains according to the types of service for easier management. A dynamic resource reservation mechanism (DRRM) is used to test users' reservation requests and reserve resources for users. According to user preference, several resources are chosen to be candidate resources by fuzzy cluster analysis. The fuzzy evaluation method and a two-way trust evaluation mechanism are adopted to improve the availability and credibility of the model. An analysis and simulation experiments show that this model can increase the flexibility of resource reservation and improve user satisfaction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.906-911
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• 2004

In the development of sheet-handling machinery, it is important to be able to predict the italic and dynamic behavior of the sheets with a high degree of reliability because the sheets are fed and stacked at such a high speed. In this paper, a spring-mass-beam model is introduced. This model consists of rotational springs, shear springs and masses. The formulations for static and dynamic behavior of sheets are introduced. And some simulations are presented for static and dynamic cases.

• Structural Engineering and Mechanics
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• v.7 no.2
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• pp.217-224
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• 1999

A semi-stochastic process model of reliability was established for hyperbolic cooling towers subjected to combined loadings of wind force, self-weight, temperature loading. Effect of the soil-structure interaction on reliability was evaluated. By involving the gust factor, an equivalent static scheme was employed to convert the dynamic model to static model. The TR combination rule was used to consider relations between load responses. An analysis example was made on the 90M cooling tower of Maoming, Guangdong of China. Numerical results show that the design not including interaction turns to be conservative.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.2
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• pp.213-222
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• 2014

In this paper, we introduce that MAAB style guideline has effects on the codes generated from Simulink models for static and dynamic software testing, when weapon system embedded software design and implementation are performed using the model based method. As showing the effects, MAAB guideline is helpful for defect prevention related with coding rules and run time errors associated with the DAPA weapon system embedded software guide. Thus, we check related items between MAAB and DAPA software reliability testing including static and dynamic analysis. And then we propose the criterion to select proper items from MAAB for DAPA guideline and show how to verify the relationship and the effects on reliability of models in Simulink. In addition, we show the needs for clear logics in conditional block models or statements and simple complexity models for Simulink model based design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.1
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• pp.19-26
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• 2015

This paper proposes a design method for improving the frequency-domain performance reliability of dynamic systems with uncertain and degrading components. Discrete frequencies are used in this method as surrogates for the frequency band of interest, and the conformance of the frequency responses to the specification at these frequencies is utilized to model the frequency-domain performance reliability. A meta-model for the frequency responses, an extreme-value event, and the set-theory are integrated to improve the computational efficiency of the reliability estimation. In addition, a sample-based approach is presented to evaluate and optimize the estimated performance reliability. A case study of a vibration absorber system showed that the proposed design method has engineering applications.

• Earthquakes and Structures
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• v.14 no.5
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• pp.425-436
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• 2018

The design of seismically isolated structures considering the stochastic nature of excitations, base isolators' design parameters, and superstructure properties requires robust reliability analysis methods to calculate the failure probability of the entire system. Here, by applying artificial neural networks, we proposed a robust technique to accelerate the estimation of failure probability of equipped isolated structures. A three-story isolated building with susceptible facilities is considered as the analytical model to evaluate our technique. First, we employed a sensitivity analysis method to identify the critical sources of uncertainty. Next, we calculated the probability of failure for a particular set of random variables, performing Monte Carlo simulations based on the dynamic nonlinear time-history analysis. Finally, using a set of designed neural networks as a surrogate model for the structural analysis, we assessed once again the probability of the failure. Comparing the obtained results demonstrates that the surrogate model can attain precise estimations of the probability of failure. Moreover, our proposed approach significantly increases the computational efficiency corresponding to the dynamic time-history analysis of the structure.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.10
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• pp.512-519
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• 2005

E-BLP security model considers the reliability of the processes that are real subjects in systems. This paper deals with the implementation of the E-BLP model for secure embedded systems. Implemented EBSM(E-BLP Based Security Module) consists of three components: identification and authentication, access control and BRC(Dynamic Reliability Check) that checks the process behavior dynamically. Access Control of EBSM ensures unreliable processes not to access the sensitive objects and the DRC detects the buffer overflow attack by normal user. Besides, the performance overhead of the embedded system applying the EBSM is introduced.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.2_2
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• pp.315-325
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• 2023

Recently, various dynamic risk analysis methods have been suggested for estimating the risk index by predicting the possibility of accidents and damage. It is necessary to maintain and support the safety system for responding to accidents by continuously updating the probability of accidents and the results of accidents, which are quantitative standards of ship risk. In this study, when a LNG leakage that may occur in the LN G Fuel Gas Supply System (FGSS) room during LN G bunkering operation, a reliability physical model was prepared by the change in monitoring data as physical parameters to estimate the accident probability. The scenario in which LNG leakage occur were configured with FT (Fault Tree), and the coefficient of the covariate model and Weibull distribution was estimated based on the monitoring data. The possibility of an LNG leakage, which is the top event of FT, was confirmed by changes in time and monitoring data. A method for estimating the LNG leakage based on the reliability physical analysis is proposed, which supports fast decision-making by identifying the potential LNG leakage at the accident.