Experimental approach to evaluate software reliability in hardware-software integrated environment

Reliability in safety-critical systems and equipment is of vital importance, so the probabilistic safety assessment (PSA) has been widely used for many years in the nuclear industry to address reliability in a quantitative manner. As many nuclear power plants (NPPs) become digitalized, evaluating the reliability of safety-critical software has become an emerging issue. Due to a lack of available methods, in many conventional PSA models only hardware reliability is addressed with the assumption that software reliability is perfect or very high compared to hardware reliability. This study focused on developing a new method of safety-critical software reliability quantification, derived from hardware-software integrated environment testing. Since the complexity of hardware and software interaction makes the possible number of test cases for exhaustive testing well beyond a practically achievable range, an importance-oriented testing method that assures the most efficient test coverage was developed. Application to the test of an actual NPP reactor protection system demonstrated the applicability of the developed method and provided insight into complex software-based system reliability. (C) 2020 Korean Nuclear Society, Published by Elsevier Korea LLC

Evaluation of effectiveness of fault-tolerant techniques in a digital instrumentation and control system with a fault injection experiment

Recently, instrumentation and control (I&C) systems in nuclear power plants have undergone digitalization. Owing to the unique characteristics of digital I&C systems, the reliability analysis of digital systems has become an important element of probabilistic safety assessment (PSA). In a reliability analysis of digital systems, fault-tolerant techniques and their effectiveness must be considered. A fault injection experiment was performed on a safety-critical digital I&C system developed for nuclear power plants to evaluate the effectiveness of fault-tolerant techniques implemented in the target system. A software-implemented fault injection in which faults were injected into the memory area was used based on the assumption that all faults in the target system will be reflected in the faults in the memory. To reduce the number of required fault injection experiments, the memory assigned to the target software was analyzed. In addition, to observe the effect of the fault detection coverage of fault-tolerant techniques, a PSA model was developed. The analysis of the experimental result also can be used to identify weak points of fault-tolerant techniques for capability improvement of fault-tolerant techniques

Internal Labor Markets and Diversification Strategies in Financial Services

This paper assesses the fit between firm-level Internal Labor Markets (ILMs) and firm diversification in the U.S. financial services sector. The sector comprises a number of related sub-industries and recent deregulation has allowed firms to construct increasingly diversified portfolios of activities across these sub-industries. Recent deregulation, particularly in banking, has also loosened geographic restrictions on firm activities. Drawing on the “resource-based view” of firm strategy, we hypothesize that firms with stronger ILMs are more likely to diversify. We find support for this view in analysis of data from the Longitudinal Household-Employer Dynamics program matched to the Longitudinal Business Database. Firms with lower net turnover, lower wage dispersion, and greater opportunities for workers inside the firm tend to be those that diversify more subsequently

QUANTITATIVE SOFTWARE RELIABILITY ASSESSMENT OF THE SAFETY CRITICAL IN NUCLEAR REACTOR PROTECTION SYSTEM

Department of Nuclear Engineeringclos

Experimental Evaluation of the Reliability of Digitalized Reactor Protection System

[No abstract available

Optimization of Test Cases for Experimental Reliability Evaluation of Digital Reactor Protection System

Software reliability to evaluate the safety of digital I&C systems was assumed as extremely low or zero. The probability of Software Failure can be evaluated by two specific tests. This work is a part of the project to quantitatively evaluate the software reliability of digital RPS; Software Logic Exhaustive Test and Hardware-Software Integrated Test. This research offers experimental importance during the reliability evaluation to obtain approximate reliability with limited test cases. On the other word, test cases with low importance, which means that the test cases occur rarely, can be screened out according to the results of this research

Perceptual Space of Superimposed Dual-Frequency Vibrations in the Hands.

The use of distinguishable complex vibrations that have multiple spectral components can improve the transfer of information by vibrotactile interfaces. We investigated the qualitative characteristics of dual-frequency vibrations as the simplest complex vibrations compared to single-frequency vibrations. Two psychophysical experiments were conducted to elucidate the perceptual characteristics of these vibrations by measuring the perceptual distances among single-frequency and dual-frequency vibrations. The perceptual distances of dual-frequency vibrations between their two frequency components along their relative intensity ratio were measured in Experiment I. The estimated perceptual spaces for three frequency conditions showed non-linear perceptual differences between the dual-frequency and single-frequency vibrations. A perceptual space was estimated from the measured perceptual distances among ten dual-frequency compositions and five single-frequency vibrations in Experiment II. The effect of the component frequency and the frequency ratio was revealed in the perceptual space. In a percept of dual-frequency vibration, the lower frequency component showed a dominant effect. Additionally, the perceptual difference among single-frequency and dual-frequency vibrations were increased with a low relative difference between two frequencies of a dual-frequency vibration. These results are expected to provide a fundamental understanding about the perception of complex vibrations to enrich the transfer of information using vibrotactile stimuli

CEO labor market and R&D investment in high-technology firms: An empirical study on the disciplinary effect of CEO labor market

Copyright © The Author(s), 2022. Published by Cambridge University Press in association with Australian and New Zealand Academy of Management.Previous corporate governance research has paid little attention to the role of chief executive officer (CEO) labor markets in controlling CEO behaviors because the CEO labor market has been considered inefficient. With the increasing mobility of top executives across firms, however, the potential of CEO labor markets to serve as an external disciplining force has been growing. In this study, we argue that CEOs will be more pressured to engage in desirable behaviors as the CEO labor market becomes more efficient. Using a longitudinal sample of S&P 1500 firms in high-technology industries in United States from 2011 to 2019, we found that CEOs tend to increase R&D investment as CEO labor market supply increases. We also found that the tendency is greater when external CEO succession is more frequent in the market. Our results demonstrate that CEO labor markets have the potential to function as an effective external governance mechanism.N