Due to advancements in technology and manufacturing capability, it is not uncommon that life tests yield no or few failures at low stress levels. In these situations it is difficult to analyse lifetime data and make meaningful inferences about product or system reliability. For some products or systems whose performance characteristics degrade over time, a failure is said to have occurred when a performance characteristic crosses a critical threshold. The measurements of the degradation characteristic contain much useful and credible information about product or system reliability. Degradation measurements of the performance characteristics of an unfailed unit at different times can directly relate reliability measures to physical characteristics. Reliability prediction based on physical performance measures can be an efficient and alternative method to estimate for some highly reliable parts or systems. If the degradation process and the distance between the last measurement and a specified threshold can be established, the remaining useful life is predicted in advance. In turn, this prediction leads to just in time maintenance decision to protect systems. In this paper, we describe techniques for mapping product or system which has degrading performance parameter to the associated classical reliability measures in the performance domain. This paper described a general modeling and analysis procedure for reliability prediction based on one dominant degradation performance characteristic considering pseudo degradation performance life trend model. This pseudo degradation trend model is based on probability modeling of a failure mechanism degradation trend and comparison of a projected distribution to pre-defined critical soft failure point in time or cycle.

In industrial situation, electronic and electro-mechanical systems have been using different type of batteries in rapidly increasing numbers. These systems commonly require high reliability for long periods of time. Wider application of battery for low-power design as a prime power source requires us knowledge of failure mechanism and reliability of batteries in terms of load condition, environment condition and other explanatory variables. Battery life is an important factor that affects the reliability of such systems. There is need for us to understand the mechanism leading to the failure state of battery with performance characteristic and develop a method to predict the life of such battery. The purpose of this paper is to develope the methodology of monitoring the health of battery and determining the condition or fate of such systems through the performance reliability to predict the remaining useful life of primary battery with load condition, operating condition, environment change in light of battery life variation. In order to evaluate on-going performance of systems and subsystems adopting primary batteries as energy source, The primitive prototype for performance reliability analysis device was developed and related framework explained.

The purpose of this paper is to examine the effects on reliability of equipment or product which spends a great deal of its time in the non-operating condition. The paper will look at the effects on the failure modes, the failure rates, the failure distribution and the possible reliability models. Many military and commercial systems experienced periods of non-operating stage throughout their life cycle, such as periods of operational storage where the system waits, ready for use. The design of such systems must account for how these periods of non-operating effects system performance. The simulation methodology for reliability analysis was developed to support the evaluation of nonoperating modes of operation of systems and subsystems. For proper handling of the non-operating environment, issues relating to non-operating failures need to be taken into consideration from design stage of the life cycle. Furthermore, the relevant environmental concerns and issues that need to be taken into consideration are discussed.

The purpose of this paper is to examine the effects on reliability of equipment or product which spends a great deal of its time in the dormant condition. Many systems experienced periods of dormancy throughout their life cycle, such as periods of operati

  The purpose of this study is to identify the factors determining users" acceptance of individualized virtual community. While there has been considerable research on the Technology Acceptance Model (TAM) that has predicted whether individuals will accep

  This paper presents the conceptual framework for estimating and predicting system’s susceptibility to failure as function of condition parameter value which is representing the current status of performance measure using on-line performance reliability.

본 연구에서는 기상청 산하 30년 이상의 관측치를 갖고 있는 기상관측소 58개 지점을 대상으로, 과거 관측자료 및 대표농도경로(RCP) 시나리오에 의한 강수량 자료를 이용하여 지점 및 지역 확률강수량을 산정하였다. 기후변화 시나리오 자료의 편의를 제거하기 위하여 분위사상법(Quantile Mapping)과 이상치 검정을 실시하였다. 이를 통해 보정된 시나리오 값을 이용하여, 빈도해석을 통한 미래 목표기간별 확률강수량의 변화율을 살펴보았다. 기후변화에 따른 미래 확률강수량은 지속시간 24hr의 경우 현재에 대비하여 RCP 4.5시나리오 에서는 지점확률강수량 값은 평균 14~22%가 증가하였으며, 지역확률강수량 값은 평균 12~22% 증가하였다. RCP 8.5 시나리오에서는 지점확률강수량 값은 평균 8~27%가 증가하였고, 지역확률강수량 값은 7~27% 증가하는 것으로 분석되었다. 기후변화로 인한 강수량의 증가와 도시화에 따른 유출특성 변화로 자연재해 발생 및 피해는 더욱 증가할 것으로 예측된다. 이에, 본 연구에서 제시한 극치통계분석 및 확률강수량 자료는 미래 홍수 안전도 및 방재시설물 설계기준을 수립하는데 기초자료로 활용할 수 있을 것으로 기대된다.

습지는 수질정화, 재해관리, 생물서식처 제공, 기후변화 대응 등의 다양한 기능을 지닌다. 특히 습지는 환경적인 이수기능 뿐만 아니라 유속과 수위를 낮추는 치수기능 목적으로도 활용이 가능하므로 하천변 인공습지의 조성은 홍수조절을 위한 새로운 대안으로 제시되고 있다. 하지만 기존 연구들은 습지의 수질정화 기능과 종의 다양성 등에 생태적 기능에 관한 것이 대부분으로, 인공습지 조성에 따른 홍수조절효과에 관한 연구는 아직 미비한 실정이다. 본 연구에서는 안양천중류 유역에 속하는 목감천에 대하여 인공습지 조성 전과 후의 수리특성 변화를 검토하였다. 이를 위해 안양천중류 유역에 속하는 목감천을 대상유역으로 하여 HEC-HMS 모형을 통한 유출량을 산정하고 수리모형인 HEC-GeoRAS모형으로 가상의 인공습지를 모형화하여 습지 조성 전·후 수위와 유속의 시공간적 분포를 분석하였다. 결과자료를 토대로 대상유역의 인공습지 조성 전·후에 대한 수리특성을 검토하고 수위, 유속 변동에 따른 목감천의 홍수저감효과를 평가하였다. 본 연구는 인공습지 조성 사업 시 사업의 타당성을 평가하며, 설계 시 기초자료로 활용될 수 있을 것으로 기대된다.