• Journal of the KSME
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• v.29 no.2
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• pp.144-152
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• 1989

피로 해석과 관련한 기초적인 사항과 실제 현업에서 해석 혹은 계측을 통하여 피로 수명을 예측 하고자 할 때 고러할 점들과 적용례를 설명하였다. 설계단계에서부터 피로해석이 실용화되고 계측 등을 통한 자료축적으로 높은 신뢰도의 구조물이 설계. 제작되었으면 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.12
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• pp.1107-1114
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• 2011

In this paper, the fatigue life of a laser peened structure was predicted. In order to calculate residual stress induced by laser peening finite element simulation was carried out. Modified Goodman equation was used to consider the effect of compressive residual stress induced by laser peening in fatigue analysis. In addition, additive adjustment factor approach was applied to consider S-N curve model uncertainty. Consequently, the reliable bounds of the predicted fatigue life of the laser peened structure was determined.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5D
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• pp.453-461
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• 2012

Life analysis is conducted for economic analysis of equipment or facilities. The purpose of life analysis is to predict future indicators for scrapping construction equipment, and establish and utilize a wide variety of business strategies according to data predictions. First, this study shows the methods to figure out average life, life expectancy and life prediction of construction equipment and the analysis of life making methods, using survival curves. Second, the study proposes and examines the life expectancy making model depending on revenues and expenses. The result of the study reveals that the economic life of the same equipment varies with expenses, revenues and the initial cost. The life expectancy making model for construction equipment reflects respective management status for equipment and will help efficient management for companies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.2
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• pp.172-180
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• 2016

A cubesat classified as a pico-satellite typically uses commercial-grade components that satisfy the vibration and thermal environmental specifications and goes into mission orbit even after undergoing minimum environment tests due to their lower cost and short development period. However, its reliability exposed to the physical environment such as on-orbit thermal vacuum for long periods cannot be assured under minimum tests criterion. In this paper, we have analysed the reliability and life prediction of the failure mechanisms of the cubesat mission board during its service life under the launch and on-orbit environment by using the sherlock software which has been widely used in automobile fields to predict the reliability of electronic devices.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.505-511
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• 2014

The EPDM(ethylene-propylene diene monomer) rubbers used for manufacturing engine radiator hoses can be degraded by locally generated electrical stress in addition to thermal and mechanical stresses. This study presents an accelerated life prediction of the EPDM rubber under electrochemical stresses using the Arrhenius formula under various aging temperatures($60^{\circ}C$, $80^{\circ}C$, and $100^{\circ}C$). The modified life prediction formula considers the relationship between the gradient($E_a/R$) and the Arrhenius constant(C). The effects of tensile strain(5%, 10%) on the life of these rubbers were investigated. The aging temperature influences EPDM rubber life, and tensile strain was predicted. It was confirmed that the modified life prediction was within the data deviation level of the test.

• Journal of Welding and Joining
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• v.13 no.2
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• pp.25-31
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• 1995

발전 Plant는 고온.고압하에서 장기간 사용되며 파손발생시는 대형 사고로 확대되므로 경년에 따 른 운용기술의 확보가 현안 과제이다. 즉, 현재의 설비를 그대로 사용할 것인가 \ulcorner 또는 교체하여 야 할 것인가\ulcorner 그대로 사용한다면 취약부위는 어디이며 언제 보수하여야 하는가 \ulcorner 또 교체한다 면 그 시기는 언제인가 \ulcorner 에 대한 기술적 예측이 필요하다 수명예측기술은 이러한 의문에 대한 해답을 주는 Plant 설비 운용기술중 가장 최신 기술분야의 하나이다. 본고에서는 보일러 부분중 가장 사용조건이 가혹하고 교체하는데 많은 비용과 시간이 소용되는 최종과열기를 대상으로 균열 전파에 의한 수명예측에 관하여 기술코자 한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.3
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• pp.30-36
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• 2013

This paper presents a method to estimate a storage life for loss of stabilizer content as storage periods using accelerated life test data. The estimate of storage life based on deterministic accelerated life test and degradation data cannot describe a condition distribution and storage life distribution. Previously, the method to show the condition distribution and storage life distribution by using gamma process has been studied. But it has limitation because it is impossible to collect the deterioration data at initial production phase. The estimated storage life presented by this study shows the similar value to previous studies and the method can describe the condition distribution and storage life distribution. So, the estimation method studied in this paper can be used for a life cycle management about deterioration of propellant for propulsion unit or components of missile, too.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.907-915
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• 1991

본 연구에서는 피로 크랙 발생 및 파단수명의 통계학적 분포특성을 명확히 하 기 위해서 단축인장을 받고, 크랙 선단 곡율반경이 일정한 중앙 크랙을 가진 81개의 시험편을 사용하여 4개의 응력 레벨하에서 피로 시험을 행한후 많은 데이터들로 부터 피로크랙의 발생, 파단특성에 대한 신뢰성 있는 통계학적 확률특성을 제시하고, 이들 데이터를 활용하여 수명예측을 행해보고저 한다.

• Journal of the Korean Data and Information Science Society
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• v.8 no.1
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• pp.21-30
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• 1997

In accelerated life tests, the failure time of an item is observed under a high stress level, and based on the time the performances of items are investigated at the normal stress level. In this paper, when the mean of the prior of a failure rate is known in the exponential lifetime distribution with censored accelerated failure time data, we utilize the empirical Bayesian method by using the moment estimators in order to estimate the parameters of the prior distribution and obtain the empirical Bayesian predictive density and predictive intervals for a future observation under the normal stress level.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.338-343
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• 2018

Recently, a computer numerical control (CNC) machine is used widely for mold making in various industries. In the operation of a CNC machine, the production quality and safety of workers are becoming increasingly important as the product process increases. A variety of tool life prediction studies has been conducted to standardize the quality of production and improve reproducibility. When the tool life is predicted using the conventional tool life equation, there is a large error between the experimental result and result by the conventional tool life equation. In this paper, an algorithm that can predict the precise tool life was implemented using a genetic algorithm.