• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.531-534
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• 2005

The basic prediction model was constructed to obtain optimal maintenance method for concrete structure under marine environment by exploring the mechanism of mono and combined deterioration in lab. This model was planned to be upgraded with data acquired from several exposure specimens under same environment as structures. The computer program developed to give useful guidance observer would be improved. Several repair materials and repair construction methods applied to exposure specimens will be tested for its performance of prohibit salt attack and freezing & thawing action during experimental period about ten years. All of these data could be available to complete the prediction system. The manager will be able to use the system for optimal maintenance of marine concrete structures.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2042-2043
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• 2008

수력발전기의 운전중 신뢰성 및 장기 사용된 발전기의 경우 노후도 평가를 위한 지표로 고정자권선의 물리적 절연상태를 평가하는 방법이 일반적으로 이용되고 있다. 시험방법은 크게 부분방전 특성을 검출하는 운전중(On-line) 진단기법과 정지중(Off-line) 진단기법이 있다. 운전중 진단기법은 발전기의 정지없이 상시 상태를 감시할 수 있는 장점이 있으므로 활용도가 증가되고 있고 정지중 진단기법은 고정자권선 절연상태를 정밀하게 평가할 수 있는 잘 알려진 시험법으로 권선의 절연상태를 모니터링하여 운영자에게 고장징후를 알려주고, 예측보전이 가능하도록 도움을 주고 있다. 이 논문에서는 장기간 운영된 대용량 수력발전기의 정지중 절연진단기법(성극지수, 교류전류, 유전정접, 부분방전) 결과의 통계적 추이변화 고찰을 통하여 대용량 수력발전기 고정자 권선의 신뢰성평가를 실시하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.260-266
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• 2009

Non-revenue water reduction(NRW) technologies are implemented to evaluate and manage leakages scientifically in water distribution systems under local governments. A development of quantitative leakage indicator by measuring minimum night flow, pressure control policy by installation of PRV(pressure reducing valve) and the establishment of leakage prevention schemes by residual life modeling of deteriorated water pipes are reviewed and studied. Estimation models of allowable leakage are developed by measuring and analyzing minimum night flow at residential and commercial area in Nonsan city, which is suggested from UK water industry and can improve an existing leakage indicator for the evaluation of non-revenue water. Also, pressure control method is applied and analyzed to Uti distribution area in Sacheon city in the operation aspect. As results, $466\;m^3/day$ of leakage can be reduced and it is expected that 113million won of annual cost can be saved. In the part of corrosion velocity and residual life assessment, non-linear prediction models of residual thickness are proposed by assessment of corrosion velocity based on exposure years, soil and water quality etc., since the deteriorated water pipe play a major role to increase leakage. It is expected that collection data and analyzing results can be applied effectively and positively to reduce non-revenue water by accumulating surveying data and verifying the results in the business field of water distribution systems under local governments.

• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.65-71
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• 2019

In this study, as a part of the aging aircraft performance improvement project for which no design information is provided, a new type of blade antenna is installed on the main part of the aging aircraft, and the method of proving the fatigue life of the main part of the aircraft is reviewed and summarized. There are various methods to prove fatigue life according to the manufacturer and aircraft design conditions. The fatigue life prediction and damage tolerance range of the relevant site were obtained through related regulations and industry examples. From these results, the fatigue life of newly installed antennas around the main parts of the aging aircraft was evaluated and the maintenance period and criteria were set according to the damage tolerance.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.275-287
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• 2017

During the feasibility study of new rail lines, maintenance cost of railway infrastructure has mostly been estimated based on the track length and on simplified parameters; however, the estimation reliability can be improved by employing the correction factor from UIC 715, as well as the line classification in UIC 714. The correlations between maintenance cost and various parameters such as weighted track length based on line classification, radius of curvature, gradient and worn -out rate have been analyzed according to the case studies. Prediction of the maintenance cost has been carried out using the cost data, which were representative of the whole cost data; as a result, it was demonstrated that a cost model based on the line classification and the correction factor was more reliable than the existing models. Furthermore, possibilities of using data from both the track measurement vehicle and from the maintenance information system, which are under development, have been investigated and, based on this investigation, a combined cost model using line classification, radius of curvature, gradient and worn-out rate, among other factors, will be proposed in the near future.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.463-465
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• 2024

본 연구는 중국 동북3성과 우리나라간의 카페리 화물 물동량 예측을 수행하여 노후 카페리선박에 대한 경제성 평가에 기초자료로 활용하고자 하며 친환경 선박으로의 대체하는데 있어 정책금융 지원에 대한 근거자료를 확보 하고자 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.1
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• pp.52-57
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• 2007

One of the hot issues in composite patching is to reduce the thermal residual stresses between composite patch and aluminum surface which occurs after bonding of composite patch. In this study, the edge crack patching is adopted for different curing cycles. For the analysis, three layer Mindlin plate elements are used, and Paris' law is adopted to predict the fatigue life of composite patch plate. The analysis results show a good agreement with the experimental fatigue life and this technique can be applied for the prediction of fatigue life of aircraft structures.

• Journal of Teachers' Pension
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• v.2
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• pp.209-241
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• 2017

본 연구에서는 2016년도 말 현재 사학연금의 연금부채 규모를 추정하고 이를 기반으로 연금기금의 적립수준을 평가한다. 연금부채 산정방식으로는 보편적으로 적용되고 있는 예측단위적립방식과 더불어 가입연령방식을 적용하였다. 예측단위적립방식은 발생주의 회계원칙에 가장 적합한 재정방식인 반면, 가입연령방식은 연금제도의 지속을 전제로 하는 공적연금제도의 특성을 가장 잘 반영할 뿐만 아니라 안정적 제도운영을 위한 비용 수준 역시 확인할 수 있도록 해주는 장점이 있기 때문이다. 예측단위적립방식과 가입연령방식의 적용 시 연금부채는 각각 114.4조원과 115.1조원으로 나타났으며, 연금부채 대비 적립기금 비율인 적립률은 각각 14.3%와 14.2%로 산출되었다. 또한 가입연령방식의 연금부채평가를 위해 산출한 가입연령별 수지상등 표준부담률은 현재 사학연금제도에서 적용하고 있는 부담률을 크게 상회하는 것으로 파악된다. 이러한 분석 결과는 연금재정의 지속가능성 측면에서 그 미래가 낙관적이지 못하며 이를 개선하기 위한 방안이 강구되어야 함을 시사한다. 다만 연금부채를 통한 재정진단 시에는 공적연금제도로서 사학연금이 지니는 특수성을 고려해야 한다. 우리나라의 공적연금은 제도의 도입목적에 따라 가입자의 부담수준에 비해 후한 급여체계로부터 시작되었기 때문이다. 따라서 민간 부문에서와 유사한 수준의 기금적립은 기대하기 어려울 수밖에 없다. 이를 감안하지 않을 경우 상기의 분석결과는 노후소득보장이라는 본연의 목적보다 재정안정화 수단만을 위한 근거로 이용될 수 있음에 유의해야 한다.

• 한국노년학
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• v.32 no.4
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• pp.1119-1135
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• 2012

The single and the married couples elderly are rapidly increasing in the next twenty years. Due to the size of these group, their level of living, life satisfaction, income and medical security and welfare services utilization have been a social issue in Korea. For these reasons, the purpose of this study was to analyze the determinants of welfare services utilization by the single and the married couples elderly. Their analyses were composed of a cross-tabulations and t-test, analysis of variance, duncan test, multiple regression analysis using 5'th Wave Korea Welfare Panel(2010). Data were collected from a survey of 2,716. The results showed that the elderly single women had the lowest level of income and health, the elderly single men needed the help about the emotional support for improvement of family and social relations. The married couples elderly are young and the participation rate of job opportunities for the elderly is high, relatively. The results of the multiple regression analysis indicated that the level of income and medical security and the satisfaction of family relationships were important factors as related to the welfare services utilization.

• Journal of the Korean Institute of Gas
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• v.7 no.2 s.19
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• pp.1-6
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• 2003

In this work, procedure evaluating failure modes such as pipe rupture, large scale leak, and small scale leak was suggested using equations to assess remaining strength by corrosion failure. Additionally, the method to predict probability of failure was suggested according to the aforementioned failure modes, and by combining data on corrosion rate, probability of long-term failure can be induced. This work will be very useful in predicting lifetime or exchanging period of pipeline.