• 한국압력기기공학회 논문집
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• 제4권2호
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• pp.13-19
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• 2008

In order to predict a remaining life of a plant, it is necessary to select the components that are critical to the plant life. The remaining life of those components shall be evaluated by considering the aging effect of materials used as well as numerous factors. However, when evaluating reliability of nuclear structural components, some problems are quite formidable because of lack of information such as operating history, material property change and uncertainty in damage models. Accordingly, if structural integrity and safety are evaluated by the deterministic fracture mechanics approach, it is expected that the results obtained are too conservative to perform a rational evaluation of plant life. The probabilistic fracture mechanics approaches are regarded as appropriate methods to rationally evaluate the plant life since they can consider various uncertainties such as sizes and shapes of cracks and degradation of material strength due to the aging effects. The objective of this study is to evaluate the structural integrity for a reactor pressure vessel under the small break loss of coolant accident by applying the deterministic and probabilistic fracture mechanics. The deterministic fracture mechanics analysis was performed using the three dimensional finite element model. The probabilistic integrity analysis was based on the Monte Carlo simulation. The selected random variables are the neutron fluence on the vessel inside surface, the content of copper, nickel, and phosphorus in the reactor pressure vessel material, and initial RTNDT.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 추계학술발표회논문집(1)
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• pp.244-250
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• 1997

The mean time to failure (MTTF) expressing the mean value of the system life is a measure of system effectiveness. To estimate the remaining life of component and/or system, the dynamic mean time to failure concept is suggested. It is the time-dependent Property depending on the status of components. The Kalman filter is used to estimate the reliability of components using the on-line information (directly measured sensor output or device-specific diagnostics in the intelligent sensor) in form of the numerical value (state factor). This factor considers the persistency of the fault condition and confidence level in measurement. If there is a complex system with many components, each calculated reliability's or components are combined, which results in the dynamic MTTF or system. The illustrative examples are discussed. The results show that the dynamic MTTF can well express the component and system failure behaviour whether any kinds of failure are occurred or not.

• International Journal of Reliability and Applications
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• 제7권2호
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• pp.177-186
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• 2006

Typical confidence intervals for a mean or mean residual life (MRL) are centered about the mean or mean residual life. We discuss novel confidence intervals that produce statements like "we are 95% confident that the MRL function, e(t), is greater than a prespecified $\mu_o$ for all t in the interval [0, $\hat{\theta})$)" where $\hat{\theta}$ is determined from the sample data, confidence level, and $\mu_o$. Also, we can have statements like 'we are 95% confident that the MRL of population 1, namely $e_1$(t), is greater than the MRL of population 2, $e_2$(t), for all t in the interval [0, $\hat{\theta}$)" where $\hat{\theta}$ is determined from the sample data and confidence level. We illustrate these one and two sample confidence intervals on internal bonds (tensile strengths) for an important modem engineered wood product, called medium density fiberboard (MDF), used internationally.

• 조명전기설비학회논문지
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• 제22권10호
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• pp.49-55
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• 2008

본 논문은 확률분포를 이용하여 전력설비의 기대여명을 산출하는 방법을 제안한다. 전력설비의 기대여명이란 해당 설비의 잔존수명으로, 기대여명은 전력시스템의 보수계획, 설비교체계획, 신뢰도 평가에 유용하게 이용될 수 있다. 본 논문에서는 각 운전년수별로 향후 운전가능년수에 대한 누적확률을 계산하고, 계산한 누적확률로 누적확률분포함수모델의 모수를 결정한 후, 모델함수의 평균값을 구하여 기대여명을 산정한다. 제안한 방법에서는 정립한 누적확률분포함수모델을 이용하여 기대여명 뿐만 아니라, 향후 특정 운전년수에 이르기 위한 기대확률까지도 쉽게 구할 수 있다. 제안한 방법은 우리나라 복합화력 발전소 발전기의 기대여명 추정에 적용하여 그 효용성을 입증하였다.

• 한국도로학회논문집
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• 제13권4호
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• pp.71-79
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• 2011

국내 고속도로의 교량은 2000년 이후 집중된 선형개량 및 신규 노선 증가 사업으로 10년 전과 비교하여 2배 이상 증가하였다. 이에 따라 유지관리 비용도 지속적으로 증가하고 있다. 현재 고속도로 유지관리 예산 비중이 가장 높은 항목은 아스팔트 교면 교량의 콘크리트 바닥판 열화에 의한 보강 부분이다. 2011년 고속도로 관리교량은 약 7,800여개에 도달한 시점에서 현재 방법으로는 향후 어느 정도 바닥판 보강 예산이 필요한지 어느 시기에 증액을 하여야되는지 명확하게 추정하기 어렵다. 본 연구에서는 신뢰도 분석 방법인 와이불 분포에 의한 생존 수명 예측 기법을 적용하여 현재 고속도로 아스팔트 계열의 교면 교량의 평균 수명을 추정하였고 이를 토대로 향후 예상 보강 비용을 추정하였다.

• International Journal of Industrial Entomology and Biomaterials
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• 제35권1호
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• pp.30-38
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• 2017

The red-spotted apollo butterfly, Parnassius bremeri Bremer, 1864 (Lepidoptera: Papilionidae), is an endangered species in South Korea. Development and application of molecular markers to assess population genetics perspectives can be used as a basis to establish effective conservation strategies. In this study, we developed 12 microsatellite markers specific to P. bremeri using Illumina paired-end sequencing and applied the markers to South Korean populations to understand population characteristics. Genotyping of 40 P. bremeri individuals from three localities showed that at each locus, the observed number of alleles ranged from 6 to 22 and the observed and expected heterozygosities were 0.500-1.00 and 0.465 to 0.851, respectively. Significant deviation from the Hardy-Weinberg equilibrium was not observed in all loci studied. The population based $F_{ST}$ and $R_{ST}$ collectively suggest that at least the Samcheok population in northernmost Gangwon Province has a significant divergence from the remaining two populations (P < 0.01), and this result is also reflected in the forewing length. Further studies with an increased sample size will be necessary to draw robust conclusions and devise conservation strategies.

• 여성건강간호학회지
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• 제9권4호
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• pp.467-478
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• 2003

Purpose: This study investigated elderly women's health care at doctorless farm villages based on information-about the perception and management of their health. Method: Grounded theory method as mapped out by Strauss and Corbin-was used to record and transcribe open-ended interviews. The data from these interviews were analyzed. Result: We found 18 categories and 28 sub-categories. In data analysis, the core phenomenon was named "movement in pain". Causal condition as essential prerequisites were aging symptoms, bad state of health, comfortable life to live alone, longevity, deficiency of health care resources, and sub-categories of the phenomena revealed acceptance of discomfort, enduring pain, continuity of movability. Elderly women's health-related activities included enduring as it is, movement consciously, applying resources, difficult in using health medical institutions. Family support, economic level, disease condition, support system of community were influenced to their health-related activities. Consequently, the results indicated that they wanted to accept given life, expected easy death. held out remaining life. Conclusion: This study revealed that the most important factor of elderly women's health care was "movement in pain". On the basis of this study, we needed to develop diverse nursing implementation plans for maintaining and improving' movability without pain'.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(II)
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• pp.483-488
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• 2003

Calibration and gauge factor readjustment process made for the health monitoring system installed in the railway bridges is reviewed and some findings are explained in this study: specifically, the calibrators made for this purpose are illustrated and the regression processes of the calibration on long-term displacement using water level sensor, longitudinal displacement using LVDT sensor, instantaneous displacement using LVDT sensors and accelerometer are described in details. Based on the regression results, new gauge factors are obtained from regression equation and another verification is made by performing another calibration again with new factors. From the second calibration, it was found that the suggested regression curves and their factors are appropriate and much better results are expected. Future work will be concentrated on the long-term analysis of the measurement data and on the database structures so that the assessment of the structure such as damage detection and remaining life estimation is possible.

• 전기학회논문지
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• 제65권1호
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• pp.214-218
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• 2016

Catenary maintains the tension of the catenary using automatic tensioning devices to meet performance require m ents exhibited by the house is generated in accordance with the new external temperature changes. Double spring type autom a tic tensioning device is permanent and does not require the usual maintenance, and a deterioration due to no recognizable ab normalities characteristic of the nature of the internal state has the disadvantage that can not be confirmed. The disassembled for automatic spring-tension capabilities ensure efficient operation and life expectancy of the adjustment device via a check by analyzing the changes in old age determine the remaining lifetime is expected to be available as a basis for maintenance in the future.

• 한국건설관리학회논문집
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• 제6권2호
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• pp.111-119
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• 2005

일반적으로 공동주택의 수명은 50년이지만, 보통 20년이 경과하면 철거되거나 재건축되어 경제적인 낭비를 초래하고 있다. 이에 본 연구는 LCC이론을 기초로 초기투자비와 경과년수에 따른 유지관리비용의 합이 최소가 되는 시점을 추정 $\cdot$ 분석하여 공동주택의 적정 리모델링 시기를 도출함을 목적으로 하였다. 본 연구의 결과를 보면 내용년수 50년까지의 건축물의 생애 총유지관리비용의 합은 초기투자비의약 4.69배가 되고, 공동주택의 적정 리모델링 시기는 할인율 $4.17\%$를 적용했을 경우 30년으로 파악되었으며 서울시에서 발표한 법정허용년수인 40년이 경제수명으로 설정되려면 할인율은 $6.122\%$가 설정되어야 한다. 또한 할인율 변동에 따른 민감도 분석결과 할인율이 감소할 경우 적정 리모델링 시기는 연장되며, 증가할 경우 단축되는 것으로 나타났다. 이에 본 연구의 결과는 공동주택의 철거 또는 재건축 시기를 예측할 수 있으며, 보수 및 대수선의 적절한 시기를 예측하여 공동주택의 수명을 최대한 연장시킬 수 있는 기초자료로 활용될 수 있을 것으로 기대한다.