Sangdo Lee¹, Jun-Ho Huh^2,*

CMC-Computers, Materials & Continua, Vol.69, No.3, pp. 3659-3684, 2021, DOI:10.32604/cmc.2021.015632

Abstract An analysis of the recent major security incidents related to industrial control systems, revealed that most had been caused by company employees. Therefore, enterprise security management systems have been developed to focus on companies’ personnel. Nonetheless, several hacking incidents, involving major companies and public/financial institutions, were actually attempted by the cooperative firms or the outsourced manpower undertaking maintenance work. Specifically, institutions that operate industrial control systems (ICSs) associated with critical national infrastructures, such as traffic or energy, have contracted several cooperative firms. Nonetheless, ICT's importance is gradually increasing, due to outsourcing, and is the most vulnerable factor in security. This… More >

Ruiyuan Xue¹, Shurong Yu^{1, *}, Xiheng Zhang¹

CMC-Computers, Materials & Continua, Vol.65, No.1, pp. 789-805, 2020, DOI:10.32604/cmc.2020.011340

Abstract Nuclear power plants (NPP) contain plenty of valve piping systems (VPS’s) which are categorized into high anti-seismic grades. Tasks such as seismic qualification, health monitoring and damage diagnosis of VPS’s in its design and operation processes all depend on finite element method. However, in engineering practice, there is always deviations between the theoretical and the measured responses due to the inaccurate value of the structural parameters in the model. The structure parameters identification of VPS within NPP is still an unexplored domain to a large extent. In this paper, the initial 2Dfinite element model (FEM) for VPS with a DN80… More >

Jin-Ho Park¹, Joon-Hyun Lee²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.13, No.4, pp. 65-66, 2009, DOI:10.3970/icces.2009.013.065

Abstract The on-line structural integrity monitoring systems and the related techniques have been developed in Korean nuclear power plant for the purpose of Condition Based Maintenance(CBM). There are four different kinds of systems such as IVMS(Internal Vibration Monitoring System), LPMS(Loose Part Monitoring System), ALMS(Acoustic Leak Monitoring System), and RCP-VMS(Reactor Coolant Pump Vibration Monitoring system). The purpose of the IVMS is to monitor and diagnose the axial preload of the core support barrel and the abnormality of the motion of the fuel bundles inside the reactor pressure vessel. The LPMS is being operated to detect and alarm the presence of loose parts… More >

Heekun Ju, Hyung-Jo Jung^*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.1, pp. 7-7, 2019, DOI:10.32604/icces.2019.05846

Abstract Latin hypercube sampling (LHS) is widely applied to estimate a probabilistic floor response spectrum (FRS) of nonlinear nuclear power plant (NPP) structure. ASCE 4-16 Standards recommend that the minimum number of simulations should be larger than 30 when using LHS. Although this recommendation is commonly used for the minimum number of the simulation, there is no theoretical background. The variability of the estimations may exist according to the number of the simulation. Stated differently, the minimum number of the simulation may be varied depending on the characteristics of the problem (i.e., problem-dependent). In this context, the required sample size of… More >

Hyung-Jo Jung, Heekun Ju

The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.1, pp. 6-6, 2019, DOI:10.32604/icces.2019.05761

Abstract The floor response spectrum (FRS) of a nuclear power plant (NPP) structure considering nonlinear behavior of shear walls is numerically investigated. The Hysteretic Material from OpenSees program is applied to a lumped-mass model to consider the nonlinear hysteretic behavior of the element representing the shear wall. Parameters that determine the hysteretic behavior are changed to examine the effects of the parameters on the resulting FRS. The pinching effect, damage due to ductility and energy, and degraded unloading stiffness can be considered with changes in parameter values. The hysteretic behavior of the structure with different parameter values was analyzed. Elements in… More >