• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.37-40
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• 2008

We have concentrated on the performance improvement of each part for durability, safety and cost of high pressure storage system for fuel cell vehicle so far. But for the mass production of fuel cell vehicle, it is necessary to evaluate durability and safety in system module. We built the standard to evaluate and collision safety of high pressure storage system for fuel cell vehicle, and could verify reliability of high pressure storage system.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.4 s.19
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• pp.26-35
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• 2004

The ASTP is the standard of the assessment ASRP that is monitoring the performance, reliability and safety characteristics of the ammunition items. The ASTP used in domestic now has applied to US Army's grade system and grading criteria so that it cause some problems. To resolve these problems of ASTP, we surveyed both the quality level of production and the field management of ammunition, which compared with grade system and classification criteria. As a result of study, we changed grade system from four steps to three steps and applied the Korean Military Specifications and the Malfunction Criteria to the classification criteria of grades. We are looking forward to improving the reliability and effectiveness of ASRP assessment by simplifying grade system and generalizing grading criteria of ASTP.

• International Journal of Reliability and Applications
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• v.9 no.2
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• pp.125-140
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• 2008

The new better than used failure rate (NBUFR), Abouammoh and Ahmed (1988), and new better than average failure rate (NBAFR) Loh (1984) classes of life distributions, have been considered in the literature as natural weakenings of NBU (NWU) property. The paper considers testing exponentiality against strictly NBUFR (NBAFR) alternatives, or their duals, based on goodness of fit approach that is possible in life testing problems and that it results in simpler procedures that are asymptotically equivalent or better than standard ones. They may also have superior finite sample behavior. The asymptotic normality are proved. Powers, Pitman asymptotic efficiency and critical points are computed. Dealing with censored data case also studied. Practical applications of our tests in the medical sciences are present.

• Proceedings of the Safety Management and Science Conference
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• 2001.05a
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• pp.149-160
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• 2001

The components of dependability are reliability, availability, maintainability, safety. The dependability thus often designated in terms of RAMS. International Standard IEC 60300 Dependability Management Part 3-5(IEC 60300-3-5) involves application guides of Reliability test conditions and Statistical test principles. This report presents the basic concepts of IEC 60300-3-5 and explanation of its detailed clauses.

• IE interfaces
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• v.12 no.3
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• pp.448-457
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• 1999

Accelerated degradation is concerned with models and data analyses for degradation of product performance over time at overstress and design conditions. Although there have been numerous studies with accelerated degradation theory in reliability, very few actually apply to parametric statistical analyses. This paper shows how to analyze degradation data, provides tests for how well the assumptions hold. Reel sensors, a sort of photointerrupters in home VCR, hive been tested, and least-square analyses are used to illustrate our approach. Tests for linearity of the performance-time relationship, dependence of the lognormal distribution, and the standard deviation on time are performed. The mean life of tested sensors is assessed at about 414,000 hours, and the Arrhenius activation energy of this reaction is concluded to be 0.39 eV as results.

• Structural Engineering and Mechanics
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• v.32 no.1
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• pp.37-53
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• 2009

In this paper the problem of calculating the probability that the responses of a wind-excited structure exceed specified thresholds within a given time interval is considered. The failure domain of the problem can be expressed as a union of elementary failure domains whose boundaries are of quadratic form. The Domain Decomposition Method (DDM) is employed, after being appropriately extended, to solve this problem. The probability estimate of the overall failure domain is given by the sum of the probabilities of the elementary failure domains multiplied by a reduction factor accounting for the overlapping degree of the different elementary failure domains. The DDM is extended with the help of Line Sampling (LS), from its original presentation where the boundary of the elementary failure domains are of linear form, to the current case involving quadratic elementary failure domains. An example involving an along-wind excited steel building shows the accuracy and efficiency of the proposed methodology as compared with that obtained using standard Monte Carlo simulations (MCS).

• Journal of Applied Reliability
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• v.9 no.1
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• pp.37-45
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• 2009

Recently mechanical watt-hour meters are being replaced by electronic watt-hour meters. The replacement period of mechanical watt-hour meters is 7 years. This period is based on long term historical data. The replacement period of electronic watt-meters is also 7 years. This period is determined using the replacement period of mechanical watt-hour meters. However lifetime of mechanical watt-hour meters is different from the lifetime of electronic meters. In order to determine desirable replacement period of electronic watt-hour meters, accelerated life tests of major components in electronic watt-hour meters were performed. The test results showed that LCD was the component which had the shortest lifetime. In this paper, lifetime of electronic watt-hour meters manufactured by 3 company was estimated and life test standard for LCD was developed.

• Journal of the Korean Society of Systems Engineering
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• v.11 no.1
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• pp.49-54
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• 2015

The RAMS Process is the Internationally required activity to secure Reliability, Availability, Maintainability, and Safety of system which will be acquired as customer requirements. The importance are situations that have been growing gradually. Specially, When developing railway system, the needs of customer about RAMS Process has been being proposed in a variety of railroad business. Through this paper, It introduces the international standards described the RAMS Process and also presents the requirements that should have to comply with it. Furthermore, the necessary activities to get certificate of a Railway system are suggested and not only the various acquisition cases of certificate but also lessons learned by cases in the field of railway signalling system are presented.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1836-1839
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• 2005

We have developed Ethernet based real-time communication systems called "Vnet/IP" for DCS which is the control system for process automation. This paper describes the features and the technologies of the ASIC which is utilized in the communication interface hardware for Vnet/IP. Vnet/IP has been developed for mission-critical communications. Hence it has real-time feature, high reliability and precise time synchronization capability. At the same time, it is able to deal with standard protocols without influence on mission-critical communications. The communication interface hardware has a host interface and dual redundant network interfaces. The host interface can be chosen PCI-bus or R-bus which is the proprietary internal bus developed for the high reliable redundant controller. Each network interface is a RJ45 connection with 1Gbps maximum in compliance with IEEE802.3.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.10
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• pp.99-108
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• 2007

As the structure of a mobile phone becomes thin to catch up with a slim product trend, the reliability of a LCD module is on the rise as a big issue for a product design. A drop test is the most basic and important verification method for a mechanical quality control but it requires much time and cost during a product development process. Thus many manufacturers have considered design guide lines using CAE and simulation for more effective usage of limited resources on the market. In this paper, the Maximum Principle Stress of a LCD glass panel is calculated on the basis of explicit FE Analyses method and input conditions are determined according to the general test standard. The design guideline for reliability improvements are suggested on the basis of the results of FE Analysis.