• 한국안전학회지
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• 제30권3호
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• pp.13-19
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• 2015

Railway vehicle equipment goes back again to the state just before when failure by the repair. In repairable system, we are interested in the failure interval. As such, a statistical model of the point process, NHPP power law is often used for the reliability analysis of a repairable system. In order to derive a quantitative reliability value of repairable system, we analyze the failure data of the air brake system of the train line 7. The quantitative value is the failure intensity function that was modified, converted into a cost-rate function. Finally we studied the optimal number and optimal interval in which the costs to a minimum consumption point as cost-rate function. The minimum cost point was 194,613 (won/day) during the total life cycle of the braking system, then the optimal interval were 2,251days and the number of optimal preventive maintenance were 7 times. Additionally, we were compared to the cost of a currently fixed interval(4Y) and the optimum interval then the optimal interval is 3,853(won/day) consuming smaller. In addition, judging from the total life, "fixed interval" is smaller than 1,157 days as "optimal interval".

• Structural Monitoring and Maintenance
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• 제2권2호
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• pp.133-143
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• 2015

Civil engineering infrastructure is aging and requires cost-effective maintenance strategies to enable infrastructure systems operate reliably and sustainably. This paper presents an approach for determining risk-cost balanced repair strategy of corrosion damaged reinforced concrete structures with consideration of uncertainty in structural resistance deterioration. On the basis of analytical models of cover concrete cracking evolution and bond strength degradation due to reinforcement corrosion, the effect of reinforcement corrosion on residual load carrying capacity of corroded reinforced concrete structures is investigated. A stochastic deterioration model based on gamma process is adopted to evaluate the probability of failure of structural bearing capacity over the lifetime. Optimal repair planning and maintenance strategies during the service life are determined by balancing the cost for maintenance and the risk of structural failure. The method proposed in this study is then demonstrated by numerical investigations for a concrete structure subjected to reinforcement corrosion. The obtained results show that the proposed method can provide a risk cost optimised repair schedule during the service life of corroded concrete structures.

• 한국신뢰성학회지:신뢰성응용연구
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• 제18권2호
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• pp.114-121
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• 2018

Purpose: This study proposes a process for evaluating the preventive maintenance policy for a system with degradation characteristics and for calculating the appropriate preventive maintenance cycle using time- and condition-based maintenance. Methods: First, the collected data is divided into the maintenance history lifetime and degradation lifetime, and analysis datasets are extracted through preprocessing. Particle filter algorithm is used to estimate the degradation lifetime from analysis datasets and prior information is obtained using LSE. The suitability and cost of the existing preventive maintenance policy are each evaluated based on the degradation lifetime and by using a minimum repair block replacement model of time-based maintenance. Results: The process is applied to the degradation of the reverse osmosis (RO) membrane in a seawater reverse osmosis (SWRO) plant to evaluate the existing preventive maintenance policy. Conclusion: This method can be used for facilities or systems that undergo degradation, which can be evaluated in terms of cost and time. The method is expected to be used in decision-making for devising the optimal preventive maintenance policy.

• 기본간호학회지
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• 제8권3호
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• pp.391-401
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• 2001

Purpose: The purpose of this study was to identify variables that influence smoking cessation based on the transtheoretical model. Methods: Variables that influence the stages of change in smoking cessation were selected based on transtheoretical model. Data were collected from 176 men aged 30-64 who smoked, Data collection was done in community settings in Seoul and vicinity, Korea between December, 1999 and June, 2000. Data were analyzed by descriptive statistics and logistic analysis using the pc-SAS program. Results: According to the logit model, the influence of significant variables on stage of change for smoking cessation suggest that ; When the scores for Pros in decision making for smoking cessation are high, the possibility that the subjects are in the action, precontemplation and contemplation stage of change will be lower than the possibility that the subjects are in the maintenance stage of change. When the scores of habitual craving in smoking temptation is high, the possibility that the subjects are in the precontemplation and contemplation stage of change will be higher than the possibility that the subjects are in the maintenance stage of change. When the scores of smoking temptation in negative affect situations are high, the possibility that the subjects are in the contemplation stage of change will be higher than the possibility that the subjects are in the maintenance stage of change. When the scores of cognitive process in the process of change are high, the possibility that the subjects are in the contemplation stage of change will be higher than the possibility that the subjects are in the maintenance stage of change. Conclusions : The results provide evidence that physical and psychological dependence on smoking are main barriers to smoking cessation. Therefore nursing interventions based on stage that focus on increasing motivation and intention for smoking cessation need to be developed.

• International Journal of Quality Innovation
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• 제7권2호
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• pp.97-124
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• 2006

The purpose of this research is to create an expert risk-based piping system inspection model. The proposed system includes a risk-based piping inspection system and a piping inspection guideline system. The research procedure consists of three parts: the risk-based inspection model, the risk-based piping inspection model, and the piping inspection guideline system model. In this research procedure, a field plant visit is conducted to collect the related domestic information (Taiwan) and foreign standards and regulations for creating a strategic risk-based piping inspection and analysis system in accordance with the piping damage characteristics in the petrochemical industry. In accordance with various piping damage models and damage positions, petrochemical plants provide the optimal piping inspection planning tool for efficient piping risk prediction for enhancing plant operation safety.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 추계 학술논문 발표대회
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• pp.205-208
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• 2009

The purpose of this study is to apply the process model of the pre-design stage to CPLM(Construction Project Life-cycle Management). Life-cycle consists of 4 stage; Pre-design, Design, Construction, Maintenance. Each stage has organic relations between front and rear stage. Therefore it is important to manage and use the information data of each stage. But these data are not carried to the next stage smoothly, especially at the pre-design stage. It is even vague to define the process of the pre-design stage. To carry and share the information well, this study defines Pre-design stage process and CPLM at first, VA-Cityplanner which is the development system of the pre-design process model is applied to CPLM for the smooth current of the data between participants.

• 한국추진공학회지
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• 제21권3호
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• pp.91-100
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• 2017

복합화력 발전소의 가스터빈 정비 의사 결정을 지원하기 위한 솔루션을 개발하였다. 대상 엔진은 군산 복합화력 발전소에서 사용하고 있는 MHI 501G 가스터빈이다. 개발된 솔루션은 다음과 같은 모듈들을 통해 최적의 정비주기 계산 결과를 제공해주며, 각 모듈에는 실시간 성능 감시, 모델기반 성능진단, 성능 경향분석, 최적 오버홀 정비주기 예측, 압축기 최적 세정주기 관리, BPT (Blade Path Temperature) 분석 기능이 포함되어 있다. 모델 기반 성능진단은 실시간으로 계측되는 성능 파라미터 데이터와 가스터빈 시뮬레이션 결과를 비교하여 그 차이를 분석하여 진단을 수행한다. 압축기 세정주기 분석은 압축기 성능과 정비비용 사이의 최적 점을 제시한다.

• 한국시뮬레이션학회논문지
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• 제26권3호
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• pp.23-34
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• 2017

본 연구는 복수 품목을 정비하는 단일 정비부대의 정비 프로세스를 시뮬레이션으로 모델링하였다. 이를 통해 정비능력을 공유한 정비창이 최적 비용으로 구성품 가동률과 목표 가동율 등을 달성하는지를 분석할 수 있다. 구성품 가동률과 정비시간 등을 핵심 성과지표로 하여 육군 항공기 정비단 엔진 정비프로세스에 대한 시뮬레이션 모델을 구성하고 실증연구를 하였다. 영향요소의 식별을 위해 NOLH 실험설계법을 적용하여, 33가지 시나리오를 구성하고 다중회귀분석을 수행하였다. 이 비용분석 연구를 통해 정비 프로세스의 개선사항을 식별할 수 있었다. 본 연구는 시뮬레이션을 통해 복수품목을 정비하는 단일 정비부대의 비용대 효과 분석 모형을 제공했다는데 의의가 있다.

• International Journal of Ocean System Engineering
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• 제1권1호
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• pp.32-36
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• 2011

EG/AD/S type model ice was originally selected as the primary model ice material for the MOERI ice tank in Korea. The existence of a sugar component in the EG/AD/S mixture may cause a serious maintenance problem. In order to understand the influence of sugar in the original model ice, a series of tests with EG/AD/S and EG/AD model ices were performed, and their material properties compared. Because the target strength of model ice in the full-scale MOERI ice tank is expensive and difficult to control, tests were performed under cold room conditions using a miniature ice tank. This paper describes the material properties of EG/AD/S and EG/AD model ices, such as flexural strength, compressive strength and elastic modulus. In order to obtain the desired strength and stiffness levels for the model ice, a warm-up process was introduced.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.781-786
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• 2007

본 연구는 정부의 주거복지 지원계획과 관련한 공공임대주택의 양적인 공급 증가에 따라 유지관리의 필요성의 부각되고 있는 시점에서 현행 공공임대주택의 특성과 유지관리 시스템의 분석을 통해 장기적으로 유지관리방식의 문제점 개선과 효율성 향상을 위한 웹기반 유지관리 시스템으로의 발전가능성과 더불어 한계점도 파악해 보았다. 이 결과를 토대로 하여 PDA와 같은 IT를 활용한 유비쿼터스 장비의 이용가능성과 사용에 따른 기대효과를 제시함으로서 현재 연구${\cdot}$개발된 유지관리시스템의 문제점을 보완하여 사용자위주의 시스템을 제시하였다.