• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.263-269
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• 2012

Condition-based maintenance (CBM) has been used as a useful concept for optimizing maintenance plan and decreasing maintenance cost in several kinds of plant sites. This study introduced an example that developed an integrated management system for maintenance parameters and hydraulic turbine of hydro-power plant in order to improve its maintenance system as applying CBM techinique. The integrated management system consists of three parts. One is a hardware part including PDA inspection system and several kind of precision measuring instruments. Another is a vibration monitoring system on hydraulic turbine. The other is a software part that takes charge of making hierarchy tree of maintenance parameters and their inspection route, managing accumulated database, assessing health condition of components, and supporting interface with other enterprise management system. The system has been installed at Chuncheon Hydro-power plant for test and demonstration. It is expected that the system can contribute database construction for diagnostics and prognostics on facility health condition and systematic accumulation of know-how on operation and maintenance of plant.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.6
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• pp.574-581
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• 2012

Condition-based maintenance(CBM) has been used as a useful concept for optimizing maintenance plan and decreasing maintenance cost in several kinds of plant sites. This study introduced an example that developed an integrated management system for maintenance parameters and hydraulic turbine of hydro-power plant in order to improve its maintenance strategy as applying CBM techinique. The integrated management system consists of three parts. One is a hardware part including PDA inspection system and several kind of precision measuring instruments. Another is a vibration monitoring system on hydraulic turbine. The other is a software part that takes charge of making hierarchy tree of maintenance parameters and their inspection route, managing accumulated database, assessing health condition of components, and supporting interface with other enterprise management system. The system has been installed at Chuncheon hydro-power plant for test and demonstration. It is expected that the system can contribute database construction for diagnostics and prognostics on facility health condition and systematic accumulation of know-how on operation and maintenance of plant.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.2
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• pp.123-137
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• 2014

The aviation gas turbine is composed of many expensive and highly precise parts and operated in high pressure and temperature gas. When breakdown or performance deterioration occurs due to the hostile environment and component degradation, it severely influences the aircraft operation. Recently to minimize this problem the third generation of predictive maintenance known as condition based maintenance has been developed. This method not only monitors the engine condition and diagnoses the engine faults but also gives proper maintenance advice. Therefore it can maximize the availability and minimize the maintenance cost. The advanced gas turbine health monitoring method is classified into model based diagnosis (such as observers, parity equations, parameter estimation and Gas Path Analysis (GPA)) and soft computing diagnosis (such as expert system, fuzzy logic, Neural Networks (NNs) and Genetic Algorithms (GA)). The overview shows an introduction, advantages, and disadvantages of each advanced engine health monitoring method. In addition, some practical gas turbine health monitoring application examples using the GPA methods and the artificial intelligent methods including fuzzy logic, NNs and GA developed by the author are presented.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.2
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• pp.123-134
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• 1999

Hot-wire anemometers are most commonly used in measuring hood capture velocities due to their accuracy and convenience. But it was ques tionable whether they have an appropriate accuracy and they are well maintained. To answer these questions, as eries of survey and the performance test were performed. The average error turns out to be 16.93%. Many of them were out of order due to bad maintenance. They were not frequently calibrated even though the users of anemometers think the periodic calibration is necessary for maintaining the accuracy of anemometers. A possible efficient maintenance program was thus discussed.

• International Journal of Railway
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• v.1 no.3
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• pp.94-98
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• 2008

Static inverters are essential devices onboard of rolling stock. State-of-the-art static inverters have an impact on both rail infrastructure and vehicle maintenance due to their new topology with new features. The paper describes two important aspects as examples of new features available in state-of-the-art static inverters: active input current control and the effects on the rail infrastructure as well as the detection of the state of charge and the state of health of batteries to simplify vehicle maintenance.

• Journal of the Korea Safety Management & Science
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• v.9 no.3
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• pp.15-19
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• 2007

This paper proposes a maintenance method to integrate worker's safety concerns into the process activities of the manufacturing system and it is to be considered as a part of the scope of maintenance engineering. The proposed method incorporates worker's health and safety considerations into maintenance engineering in each of the manufacturing process using reliability analysis. It can help to make a better planning and implementation of maintenance activities for the manufacturing system.

• Journal of Korea Association of Health Promotion
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• v.3 no.2
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• pp.189-198
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• 2005

This study examined the applicability of the transtheoretical model(TTM) to understanding exercise behavior of early adulthood. A cross-sectional study was conducted and data wee collected from 1618 adults aged from 20 to 39 through internet survey. Major conclusions wee as follows: 1. Stage distribution for exercise behavior was 15.6%, 26%, 25%, 19%, 14.4% for precentemplation, contemplation, preparation, action, maintenance stages, respectively. 2. Behavioral processes were more frequently utilized than cognitive processes for action and maintenance stage. 3. Self-reevaluation, social liberation and reinforcement were frequently used in precontemplation, contemplation and preparation stages. Self-reevaluation, reinforcement, self-liberation were frequently used in action and maintenance stages. 4. Pros of exercise behavior began to be higher than cons of exercise behavior from the actions stage and continued to increase to maintenance stage. 5. Self-efficacy was higher in action stage than precontemplation, contemplation and preparation stages and the highest in maintenance stage.

• Journal of muscle and joint health
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• v.22 no.3
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• pp.228-235
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• 2015

Purpose: The purpose of this study was to examine factors related with the maintenance of physical activity in Korean old adults with hypertension based on the social cognitive theory. Methods: A cross-sectional survey of 300 old adults with hypertension from five public health centers in Korea was conducted using a self-reported questionnaire. Participants were designated as "maintainer" or "discontinuer" based on the reports to the Stages of Readiness to exercise Questionnaire. Results: One hundred seventeen participants (39%) were designated as maintainers. The predictors of the maintenance of physical activity were gender (OR=3.19, p=.049), education (OR=3.50, p=.049), outcome expectation (OR=1.21, p<.001), self-efficacy (OR=.22, p=.007), and physical activity planning (OR=1.19, p=.002). Conclusion: Findings from this study suggest that nursing interventions to improve the maintenance of physical activity in the hypertensive elderly should focus on increasing outcome expectation, self-efficacy, and physical activity planning strategies especially on the female elderly with lower education level.

• Safety and Health at Work
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• v.7 no.2
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• pp.120-123
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• 2016

Background: To assess in a laboratory setting the ability to stay awake in a sample of workers of an Italian hospital and to investigate the association between that ability and the risk of occupational injury. Methods: Nine workers at the University Hospital of Udine who reported an occupational injury in the study period (cases), and seven noninjured workers (controls) underwent a polysomnography and four 40-minute maintenance of wakefulness tests (MWT). Differences in sleep characteristics and in wakefulness maintenance were assessed using Wilcoxon's rank sums tests and Fisher's exact tests. Results: Controls had greater sleep latency, lower total sleep time, fewer leg movements, and a higher percentage ratio of cycling alternating pattern, were more likely not to fall asleep during the MWT and were less likely to have two or more sleep onsets. Although not all the differences reached statistical significance, cases had lower sleep onset times in Trials 1-3. Conclusion: In the literature, the evidence of an association between MWT results and real life risk of accidents is weak. Our results suggest a relationship between the MWT results and the risk of injury among hospital workers.

• Journal of muscle and joint health
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• v.22 no.1
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• pp.13-19
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• 2015

Purpose: The purpose of this study was to identify the relationships among network centrality, psychological well-being (PWBS), and intention to exercise maintenance in participants of an aquatic exercise program. Methods: Using a single-experimental design, 17 osteoarthritis patients participated in an aquatic exercise program. The questionnaire to connect the network of members was used to peer nomination by Moreno (1953). Data were analyzed with the UCINET using centrality (degree, closeness, betweenness) and SPSS using descriptive statistics, wilcoxon signed ranked test, and spearman's rho. Results: Closeness centrality, PWBS, and intention to exercise maintenance were significantly different between 4 weeks and 8 weeks. At 4 weeks, PWBS was positively correlated with closeness centrality. Intention to exercise maintenance was positively correlated with degree, closeness, and betweenness centrality. At 8 weeks, PWBS was positively correlated with closeness centrality. Intention to exercise maintenance was positively correlated with closeness centrality. Conclusion: The aquatic exercise program can be effective in increasing closeness centrality, psychological well-being, and intention to exercise maintenance. This was the first study attempted to analyze construction of member relationships in osteoarthritis patients participating an exercise program by using social network analysis.