• The Journal of Society for e-Business Studies
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• v.23 no.2
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• pp.111-121
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• 2018

Many problems in rotating machinery such as aircraft engines, wind turbines and motors are caused by bearing defects. The abnormalities of the bearing can be detected by analyzing signal data such as vibration or noise, proper pre-processing through a few signal processing techniques is required to analyze their frequencies. In this paper, we introduce the condition monitoring method for diagnosing the failure of the rotating machines by analyzing the vibration signal of the bearing. From the collected signal data, the normal states are trained, and then normal or abnormal state data are classified based on the trained normal state. For preprocessing, a Hamming window is applied to eliminate leakage generated in this process, and the cepstrum analysis is performed to obtain the original signal of the signal data, called the formant. From the vibration data of the IMS bearing dataset, we have extracted 6 statistic indicators using the cepstral coefficients and showed that the application of the Mahalanobis distance classifier can monitor the bearing status and detect the failure in advance.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.2
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• pp.29-36
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• 2014

Finite failure NHPP software reliability models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, proposes the Gompertz distribution reliability model, which made out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on mean square error (MSE) and coefficient of determination$(R^2)$, for the sake of efficient model, was employed. Analysis of failure using real data set for the sake of proposing fixed shape parameter of the Gompertz distribution was employed. This analysis of failure data compared with the Gompertz distribution model of shape parameter. In order to insurance for the reliability of data, Laplace trend test was employed. In this study, the proposed Gompertz model is more efficient in terms of reliability in this area. Thus, Gompertz model can also be used as an alternative model. From this paper, software developers have to consider the growth model by prior knowledge of the software to identify failure modes which can was helped.

• Journal of Korean Society for Quality Management
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• v.17 no.2
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• pp.17-26
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• 1989

This paper is concerned with forecasting the existing number of errors in the computer software and optimizing the stopping time of the software test based upon the forecasted number of errors. The most commonly used models have assessed software reliability under the assumption that the software failure late is proportional to the current fault content of the software but invariant to time since software faults are independents of others and equally likely to cause a failure during testing. In practice, it has been observed that in many situations, the failure rate decrease. Hence, this paper proposes a mathematical model to describe testing situations where the failure rate of software limearly decreases proportional to testing time. The least square method is used to estimate parameters of the mathematical model. A cost model to optimize the software testing time is also proposed. In this cost mode two cost factors are considered. The first cost is to test execution cost directly proportional to test time and the second cost is the failure cost incurred after delivery of the software to user. The failure cost is assumed to be proportional to the number of errors remained in the software at the test stopping time. The optimal stopping time is determined to minimize the total cost, which is the sum of test execution cast and the failure cost. A numerical example is solved to illustrate the proposed procedure.

• Journal of the Korean Society of Safety
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• v.28 no.5
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• pp.10-14
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• 2013

This paper is aimed to investigate the actual conditions of standalone PV(Photovoltaics) streetlight in public place and analyze cause of failure and derive the method of decrease for standalone PV streetlight. The cost of installing standalone PV streetlight in a public for the safety and convenience of life is expensive(300 million won per unit). Management of standalone PV streetlight is important because it is operating system itself, after installation, but concern degree of management is very low and development of technology has not been done. Accordingly, standalone PV streetlight in public place is not operate in night, this phenomenon is lasted for several days to months. Therefore this study, for standalone PV streetlight constantly to keep the normal operation, investigation conducted to check status of standalone PV streetlight(50 units), the voltage of the main parts and analyze the cause of the failure. In addition, the improvement of standalone PV streetlight is suggested by using FTA(fault tree analysis).

• Journal of the Korean Society of Systems Engineering
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• v.11 no.2
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• pp.125-135
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• 2015

Various methods have been used for safety and reliability as it becomes more difficult to ensure safety owing to the increasing complexity and scale of systems. This study aims at making it easier and more efficient to discuss risks and countermeasures for completeness, review, and knowledge transfer by improving methods to create fault tree analyses which focus on the GSN [1], which are among the methods used to describe assurance cases. More specifically, the purpose of this study is to incorporate strategy and context, GSN concepts, along with reason, which is a new concept, into FTA; the study focuses on three points. One point is support for the safety designer to draw a mutually exclusive and collectively exhaustive (MECE) FTA. The second is to make it easier to understand diagrams and meanings of FTA compared with the usual methods. The third is to make creating an FTA more efficient and to pass on existing know-how. Eventually, FTA can achieve completeness, review, and knowledge transfer. An introduction is provided in the first section. Next, the methodology covered in this paper is explained in the second section. The third section describes the proposed notation method based on two proposals made in this paper. In the fourth and fifth sections, results and discussion are provided, respectively. Finally, in the sixth section, conclusions are described.

• Journal of Information Technology Applications and Management
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• v.23 no.4
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• pp.117-125
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• 2016

Software reliability in the software development process is an important issue. In infinite failure non-homogeneous Poisson process software reliability models, the failure occurrence rates per fault. can be presented constant, monotonic increasing or monotonic decreasing pattern. In this paper, the reliability software cost model considering decreasing intensity function was studied in the software product testing process. The decreasing intensity function that can be widely used in the field of reliability using power law process, log-linear processes and Musal-Okumoto process were studied and the parameter estimation method was used for maximum likelihood estimation. In this paper, from the software model analysis, we was compared by applying a software failure interval failure data considering the decreasing intensity function The decreasing intensity function model is also efficient in terms of reliability in the arena of the conservative model can be used as an alternating model can be established. From this paper, the software developers have to consider life distribution by preceding information of the software to classify failure modes which can be gifted to support.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.4
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• pp.109-115
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• 2005

In the study, Methods for operating measures in equipment security to find out dangerousness timely in the system and to need for the prevention and measures. The method for analyzing and reconstructing the causes of accident of equipment in site, and try to save the information of site in real-time and to analyze the state of equipment to look for the factors of accidents. By this analysis, one plan for efficiency of production, Equipment Fault Diagnosis Management and security is integrating and building module of using the Fuzzy Inference based on fuzzy theory. The case study is applied to the industrial electric motors that are necessarily used to all manufacturing equipment. Using the sensor for temperature is attached to gain the site information in real time and to design the hardware module for signal processing. In software, realize the system supervising and automatically saving to management data base by the algorithm based in fuzzy theory from the existing manual input system

• Journal of the Korea Safety Management & Science
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• v.13 no.3
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• pp.1-8
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• 2011

The overall goal of a safety based railroad system is either to eliminate hazards in designing or to minimize the possibility of it. In order to indicate system safety or low risk although it may not be possible to achieve zero risk conditions, first, it shall ensure that any disasters would occur due to system operation because the prescribed specifications are properly fulfilled and there are no failures of any kind. Second, the risk of faults or failures leading to a mishap must be eliminated or minimized by using fault-tolerance or fail-safe procedures. This paper will attempt to summarize the personal and social risk criterion at widely scattered points, presently used as a safety approach in all over EU, in order to establish the step by step procedures of the detailed standard for railway facilities. In addition, we present the new safety analysis method using the SIL-based evaluation standard and the Reachability Graph of the Petri Net.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.19-27
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• 2014

Software reliability in the software development process is an important issue. Software process improvement helps in finishing with reliable software product. Infinite failure NHPP software reliability models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, proposes the reliability model with log type mean value function (Musa-Okumoto and log power model), which made out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on mean square error (MSE) and coefficient of determination($R^2$), for the sake of efficient model, was employed. Analysis of failure using real data set for the sake of proposing log type mean value function was employed. This analysis of failure data compared with log type mean value function. In order to insurance for the reliability of data, Laplace trend test was employed. In this study, the log type model is also efficient in terms of reliability because it (the coefficient of determination is 70% or more) in the field of the conventional model can be used as an alternative could be confirmed. From this paper, software developers have to consider the growth model by prior knowledge of the software to identify failure modes which can be able to help.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1648-1653
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• 2012

In general, fault of a virtually finished product that is value-added one, since it has gone throughout the most of processes, may give rise to quality cost nearly amount to its selling price and can be a main cause that decreases the efficiency of manufacturing process. This paper proposes a dispatching algorithm for manufacturing process with quality volatilities with consideration of due-dates and required quality level. In order to evaluate the proposed algorithm, this paper examines the performance of the proposed method by comparing it with that of the existing dispatching algorithms in terms of minimizing the mean tardiness. In addition, from the perspective of process capability based on required quality level, this study shows the superiority of the proposed dispatching algorithm.