• 한국안전학회지
• /
• 제12권4호
• /
• pp.180-190
• /
• 1997

A new method in the fault tree analysis (FTA) for the reliability calculation is suggested. Two steps are necessary in traditional method in evaluation of the occurrence probability of top event in fault tree (FT). The first step is to find the minimal outsets, and the second one is to substitute the result into the poincare equation. In order to reduce the enormous computing time of this method, lots of rapid algorithms have been developed. Almost of all achievements were, however, based on the partial structural properties of FT. In this paper, the FT is transformed to a non-linear graph G which has the same minimal outsets of original n, and then the reliability is calculated using the domination theory. In this new method, the required number of equation terms are at most $2^n$ (n is node number of graph G), while $2^m$-1 (m is the number of minimal cutsets) calculation terms are required in the poincare equation in traditional method. Since m>>n in general. our new method reduces the calculation time significantly.

• Journal of Electrical Engineering and Technology
• /
• 제8권4호
• /
• pp.780-786
• /
• 2013

In the reliability-based design optimization of electromagnetic devices, the accurate and efficient reliability assessment method is very essential. The first-order sensitivity-assisted Monte Carlo Simulation is proposed in the former research. In order to improve its accuracy for wide application, in this paper, the second-order sensitivity analysis is presented by using the hybrid direct differentiation-adjoint variable method incorporated with the finite element method. By combining the second-order sensitivity with the Monte Carlo Simulation method, the second-order sensitivity-assisted Monte Carlo Simulation algorithm is proposed to implement reliability calculation. Through application to one superconductor magnetic energy storage system, its accuracy is validated by comparing calculation results with other methods.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제15권2호
• /
• pp.90-100
• /
• 2015

Reliability growth rate (or reliability growth curve slope) have the two cases of trend as a constant or changing one during the reliability growth testing. The changing case is very common situation. The reasons of reliability growth rate changing are that the failures to follow the NHPP (None-Homogeneous Poisson Process), and the solutions implemented during test to break out other problems or not to take out all of the root cause permanently. If the changing were big, the "Goodness of Fit (GOF)" of reliability growth curve to test data would be very low and then reduce the accuracy of assessing result with test data. In this research, we are using Duane model and AMSAA model for assessing test data and projecting the reliability level of complex and repairable system as like construction equipment and vehicle. In case of no changing in reliability growth rate, it is reasonable for reliability engineer to implement the original Duane model (1964) and Crow-AMSAA model (1975) for the assessment and projection activity. However, in case of reliability growth rate changing, it is necessary to find the method to increase the "GOF" of reliability growth curves to test data. To increase GOF of reliability growth curves, it is necessary to find the proper parameter calculation method of interesting reliability growth models that are applicable to the situation of reliability growth rate changing. Since the Duane and AMSAA models have a characteristic to get more strong influence from the initial test (or failure) data than the latest one, the both models have a limitation to contain the latest test data information that is more important and better to assess test data in view of accuracy, especially when the reliability growth rate changing. The main objective of this research is to find the parameter calculation method to reflect the latest test data in the case of reliability growth rate changing. According to my experience in vehicle and construction equipment developments over 18 years, over the 90% in the total development cases are with such changing during the developing test. The objective of this research was to develop the newly assessing method and the process for GOF level increasing in case of reliability growth rate changing that would contribute to achieve more accurate assessing and projecting result. We also developed the new evaluation method for GOF that are applicable to the both models as Duane and AMSAA, so it is possible to compare it between models and check the effectiveness of new parameter calculation methods in any interesting situation. These research results can reduce the decision error for development process and business control with the accurately assessing and projecting result.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제5권4호
• /
• pp.427-438
• /
• 2005

This paper is concerned with the problem in predicting the reliability of an LCD product, Product reliability calculation methods classify accelerated life test (ALT) and using the reliability standard as MIL-HDBK-217F and Telcordia SR-332. The reliability standard can calculate estimating value more quickly than accelerated life test. The system MTBF was calculated in accordance of Telcordia SR-332 standard which includes directions of part electronic measurement, temperature rise and environmental test data. This research is intended to obtain the useful information for each electric design step to save time and cost.

• 한국방재학회 논문집
• /
• 제8권3호
• /
• pp.77-86
• /
• 2008

현재 사용되고 있는 여러 가지 얕은기초 침하량 예측식에 대한 신뢰성 평가를 위해 얕은기초에 대한 각종 재하시험 데이터, 기초의 형상과 위치 및 지반 원위치시험 관련사항을 조사하여 데이터베이스(D/B)로 구축하였으며 이를 바탕으로 통계분석을 실시할 수 있는 해석프로그램을 제작하여 기존 침하량 산정 공식의 정확도(accuracy)와 신뢰수준(reliability), 특히, 기존 침하량 공식의 침하비(s/B) 대비 안정성을 평가하여 기 사용 5개식에 대한 평가결과를 제시하였다. 현재수준의 분석결과는 D/B의 양과 질에 좌우되므로 양질의 데이터를 추가로 확보하고 5가지 이외의 방법까지 분석하면 신뢰성과 정확성을 파악하면서 설계에 적용할 수 있을 것으로 판단된다.

• 산업경영시스템학회지
• /
• 제43권4호
• /
• pp.123-132
• /
• 2020

Currently, there are two types of trainer in Korea : basic and advanced. Both models have been in operation for more than 10 years, and compared to the early stage of operation, reliability has gradually improved and failure rates have also entered a trend of stabilization. Therefore, it is necessary to extend the maintenance period considering economic feasibility. This study investigates the three maintenance period calculation methods: NAVAIR 00-25-403 [17], DOD, U.S. [4], CERL and US Army [3], with intention to extend the maintenance period of the trainer from current 200 hours to 400 hours. In addition, the maintenance period was calculated by the three methods with actual operational data. Common standards and procedures were established to apply operational data to the existing maintenance period calculation methods, the required reliability indicators were derived, and the maintenance periods was calculated based on the results, additionally, a review on the field applicability of the three maintenance cycles was conducted. An on-site interviews were conducted with the calculation results, and 11 out of the 15 items were expected to be extended by 400 hours. It was suggested that the remaining 4 items could be extended to 400 hours by supplementing the inspection method through additional analysis such as functional analysis, inspection content verification, and site connection.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제3권2호
• /
• pp.121-135
• /
• 1999

This paper studies the problem of inverting minimal path sets to obtain minimal cut sets for complex system. We describe efficiency of inversion algorithm by the use of boolean algebra and we develop inclusion-exclusion algorithm and pivotal decomposition algorithm for reliability calculation of complex system. Several examples are illustrated and the computation speeds between the two algorithms are undertaken.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.1025-1026
• /
• 2011

Monte Calrlo Simulation (MCS) and Sensitivity-based MCS (SMCS) are studied and compared in this paper. Quantitative analysis of the influence factors for reliability calculation accuracy is performed through a analytic function and finally applied to TEAM problem 22.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 추계학술대회 논문집
• /
• pp.328-333
• /
• 2004

With the introduction of KTX, in my view it is necessary to secure the reliability of high-speed trains, make them stabilized at the earliest moment possible, and completely digest them as our own system for the purpose of being second to none in the area of railroad business. I am going to study in this thesis through analysis of train failures by help of MKBSF calculation, breaking from the convention in maintaining the high-speed trains, in order to establish and apply the computerized system called as RCM (Reliability Centered Maintenance), foster manpower in charge of the reliability maintenance, and realize the scientific and efficient maintenance covering the whole field of maintenance. Depending on how efficiently and scientifically we can perform the maintenance activities, we will be able to not only reduce the maintenance cost but also ensure the railroad security, and as a natural consequence improve the railroad image much better.

• Nuclear Engineering and Technology
• /
• 제54권10호
• /
• pp.3595-3603
• /
• 2022

Nuclear safety-class DCS is used for nuclear reactor protection function, which is one of the key facilities to ensure nuclear power plant safety, the maintenance for DCS to keep system in a high reliability is significant. In this paper, Nuclear safety-class DCS system developed by the Nuclear Power Institute of China is investigated, the model of reliability estimation considering nuclear power plant emergency trip control process is carried out using Markov transfer process. According to the System-Subgroup-Module hierarchical iteration calculation, the evolution curve of failure probability is established, and the preventive maintenance optimization strategy is constructed combining reliability numerical calculation and periodic overhaul interval of nuclear power plant, which could provide a quantitative basis for the maintenance decision of DCS system.