• Proceedings of the Korean Reliability Society Conference
• /
• 2000.04a
• /
• pp.135-143
• /
• 2000

일반적으로 제어시스템은 독립된 기능을 갖는 전자제어모듈들로 구성되고, 제어시스템의 보수에 있어서 최소 교체단위가 전자제어모듈이기 때문에 제어시스템의 신뢰성을 평가하는 것은 전자제어모듈의 신뢰성을 평가하는 것으로부턴 출발한다. 전자모듈의 신뢰성을 평가할 때 주로 사용하는 평가척도는 MTBF이고, 제조업체에서는 일반적으로 MIL-HDBK-217의 수명예측방법을 이용하여 산출한 MTBF를 제시하고 있다. 하지만 현장의 구매자들은 물론 전자모듈을 개발하는 엔지니어도 MIL-HDBK-217 데이터를 이용한 계산만으로 산출한 MTBF가 실제 사용할 때와 큰 차이가 없는지 확인하기를 원한다. 본 논문에서는 이러한 요구에 따라서 MIL-HDBK-217의 수명예측 방법을 이용하여 예측한 수명을 가속수명시험을 통하여 보증하는 방법을 제시하고, 제시한 방법을 실제 국내에서 제작한 2종류의 전자제어모듈에 적용한 사례를 기술하였다. 국내에서 제작한 2종류의 전자제어모듈에 대하여 본 논문에서 제시한 보증시험방법에 따라서 시험한 결과 신뢰수준 60%에서 예측 수명을 보증할 수 있었고, 보증시험 후에 수명을 추정하기 위하여 추가적으로 장시간 시험하여 수명을 추정한 결과 추정된 수명이 MIL-HDBK-217을 이용하여 예측된 수명에 비하여 2.86∼3.40배길게 나타났다.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.5
• /
• pp.1455-1461
• /
• 1991

본 연구에서는 Kachanov의 재료손상(material damage)모델을 이용하여 새로운 수명예측식을 만들고, 이 수명예측식의 타당성을 조사하기 위하여, 최근에 발표된 크 립 수명과 기공분포와의 실험결과와 비교하였다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2020.11a
• /
• pp.978-981
• /
• 2020

제품이나 부품의 잔존 수명을 정확하게 예측할 수 있다면 고장이나 중단으로 인한 손실을 방지하는 것이 가능해질 것이다. 제품의 잔존 수명은 시계열 데이터 분석을 통해 예측될 수 있으며, 최근에는 딥러닝을 이용한 잔존 수명 예측 연구가 활발하게 진행되고 있다. 본 연구에서 우리는 컴퓨터 기반 시스템의 주요 고장 요소가 되고 있는 하드디스크의 잔존 수명을 예측하는 문제에 1D CNN-LSTM 을 이용한 모델을 적용하고, RMSE 와 R-Square 값을 이용해 적용한 모델의 성능을 평가하였다.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.26 no.5
• /
• pp.1-10
• /
• 2022

For Cu-Cr alloy developed for rocket engines, estimated fatigue lives were calculated using various fatigue life prediction methods and compared with fatigue life acquired from low-cycle fatigue tests. The utilized methods for fatigue life prediction are as follows: Coffin-Manson relation, plastic/total strain energy density relations, Smith-Watson-Topper relation, Tomkins relation, and Jahed-Varvani relation. As results of estimation of fatigue lives, it satisfied within scatter band two compared to the test fatigue lives in all methods. The quantitative calculation of the deviation of predicted fatigue lives gives that the total strain energy density relation presents the best result.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.3
• /
• pp.259-265
• /
• 2016

Recently, life prediction models for Pb-based and Pb-free solders used in chip resistor assemblies under thermal cycling have been introduced. The models suggest that the field lifetimes of Pb-free solders would be better than those of Pb-based solders when used for chip resistors under thermal cycling conditions, while the lifetime of the chip assemblies under accelerated test conditions show a reverse relationship. In this study, the prediction models were verified by applying the model to another research case. Finite element models were built, thermal cycling conditions were applied, and the energy densities were calculated. Finally, life prediction analysis was conducted for the cases where Pb-based and Pb-free solders were used. The prediction results were then compared with the test data of the case. It was verified that the predictions of the developed life cycle models are on the practical scale.

• Proceedings of the Korean Society for Quality Management Conference
• /
• 2004.04a
• /
• pp.95-99
• /
• 2004

장기수명특성 분포를 나타내는 제품의 유효수명 예측은 경험적인 Data와 현장정보만으로는 한계가 있으며, 이러한 한계를 극복하기 위해서는 초가속수명시험을 근거로 하는 유효수명예측이 반드시 필요한 상황이다. 그러나, 현장의 문제점은 이러한 사실을 바탕으로 하더라도 MTTF 혹은 MTBF, 심지어 Br수명분포까지도 제품 유효수명과의 상관관계가 어떻게 분포하는지에 관해 정확한 GUIDE LINE없이 적용하는 문제로 인하여 기업의 COPQ 부담이 증대하고 있다. 따라서 본 연구에서는 기업의 COPQ부담을 경감시키고, 제품의 유효수명예측의 정밀도를 향상하기 위한 대안으로서 HALT와 제품유효수명간의 상관관계를 규명하는데 주력하였다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.3
• /
• pp.273-281
• /
• 2010

In this paper, a method to predict the fatigue life of an axle drive shaft by the calibrated accelerated life test (CALT) method is proposed. The CALT method is very effective for predicting lifetimes, significantly reducing test time, and quantifying reliability. The fatigue test is performed by considering two high stress and one low stress levels, and the lifetime at the normal stress level is predicted by extrapolation. In addition, in this study, the major reliability parameters such as the lifetime, accelerated power index, shape parameter, and scale parameter are determined by conducting various experiments. The lifetime prediction of the axle drive shaft is verified by comparing the experimental results with load spectrum data. The results confirm that the CALT method is effective for lifetime prediction and requires a short test time.

• Journal of Astronomy and Space Sciences
• /
• v.15 no.2
• /
• pp.459-473
• /
• 1998

As the satellite system becomes more complex, the probability of unpredictable failures may be increased due to design inadequacy, experience deficiency, lack of problem recognition. Poor quality control, improper testing, and workmanship fault. Consequently, these problems can lead to the reduction or end of the satellite mission lifetime. This article addresses general satellite failure modes and factors influencing satellite mission life. The mission life factors of LEO sun-synchronous KOMPSAT spacecraft are investigated, in which its mission life is predicted based on these factors. Since the end of mission due to random failures is not predictable, the predictable mission life factors such as power budget, propellant budget, battery charging/discharging cycle, radiation effects payload reliability, single point failure, and redundancy are primarily investigated.

• Journal of Convergence for Information Technology
• /
• v.11 no.11
• /
• pp.44-50
• /
• 2021

Recently, enterprise storage systems that require large-capacity storage devices to accommodate big data have used large-capacity flash memory-based storage devices with high density compared to cost and size. This paper proposes a high-efficiency life prediction method with slope descent to maximize the life of flash memory media that directly affects the reliability and usability of large enterprise storage devices. To this end, this paper proposes the structure of a matrix for storing metadata for learning the frequency of defects and proposes a cost model using metadata. It also proposes a life expectancy prediction policy in exceptional situations when defects outside the learned range occur. Lastly, it was verified through simulation that a method proposed by this paper can maximize its life compared to a life prediction method based on the fixed number of times and the life prediction method based on the remaining ratio of spare blocks, which has been used to predict the life of flash memory.

• Journal of Internet of Things and Convergence
• /
• v.7 no.4
• /
• pp.9-14
• /
• 2021

In computing systems that require high reliability, the method of predicting the lifetime of a storage device is one of the important factors for system management because it can maximize usability as well as data protection. The life of a solid state drive (SSD) that has recently been used as a storage device in several storage systems is linked to the life of the NAND flash memory that constitutes it. Therefore, in a storage system configured using an SSD, a method of accurately and efficiently predicting the lifespan of a NAND flash memory is required. In this paper, a method for optimizing the lifetime prediction of a flash memory-based storage device using the frequency of NAND flash memory failure is proposed. For this, we design a cost matrix to collect the frequency of defects that occur when processing data in units of Drive Writes Per Day (DWPD). In addition, a method of predicting the remaining cost to the slope where the life-long finish occurs using the Gradient Descent method is proposed. Finally, we proved the excellence of the proposed idea when any defect occurs with simulation.