Purpose: A slurry pump for flue gas desulfurization system performs a role that discharges the slurry of a plaster shape in a thermal power plant. Since a slurry pump transfers the slurry by the centrifugal force, it has the friction wear in the impeller and liner because of the slurry. Methods: In this study, failure analysis and test evaluation on the slurry pump have been proposed and the process that reliability of the product improves through design improvement has been presented. And failure cause of typical failure case has been investigated and improvement design has been presented. Results: Reliability improvement is established by analysis of the test results of before and after acceleration test. Conclusion: This study can be provided to improve the product reliability through failure analysis of a slurry pump.

Purpose: In order to fulfill the RAMS (Reliability Availability Maintainability and Safety) requirements in Korean railway systems, specific target metrics should be measured and met the requirements when ordering a new system. This paper presents a procedure to predict and demonstrate the availability, maintainability and safety of subway elevators, escalators and PSD (platform screen doors) systems. Methods: The system manufacturer predicts availability and maintainability with lab and field tested data. After installation, availability and maintainability are demonstrated based on the actual operational data. The data was collected from the FRACAS (Failure Report and Corrective Action System). Results: Methods and process of assessing and analyzing the availability, maintainability and safety are presented for elevating services and PSD systems. The data obtained through the actual operation of the equipment is analyzed and maintained to predict the RAMS based on the component and system level failure data acquired. Conclusion: This study presented an application using IEC 62278 and operational data which can be used in the design and development stage to achieve the RAMS target value of the subway elevators, escalators and PSD systems.

Purpose: Recently, Jiang defines the tradeoff B life to minimize a sum of life lost by preventive maintenance (PM) and corrective maintenance (CM) contribution parts and sets up an optimal replacement age of age replacement policy as this tradeoff life. In this paper, Jiang's model only considering the known lifetime distribution is extended by assigning different weights to two parts of PM and CM in order to reflect the practical maintenance situations in application. Methods: The new age replacement model is formulated and the meaning of a weight factor is expressed with the implied cost of failure under asymptotic expected cost model and also discussed with one-cycle expected cost criterion. Results: The proposed model is applied to Weibull and lognormal lifetime distributions and optimum PM replacement ages are derived with corresponding implied cost of failure. Conclusion: The new age replacement policy to escape the estimation of cost of failure in classical asymptotic expected cost criterion based on the renewal process is provided.

Purpose: Environment test support is urgent for small and medium defense companies in order to improve the reliability of weapons systems. Also, to reduce the burden of test costs, the voucher system must be strengthened. Quality assurance support should be accompanied by budget support. Methods: First of all, it is necessary to expand infrastructure for test equipment that suffers shortages by considering environmental test frequency and waiting periods to reduce the time required for environmental tests. Results: In regard to the environmental test, expansion for test equipment infrastructure, security of budget for the test, establishment of test plan, education and consulting support are required to resolve some limits of small and medium defense companies. Conclusion: Along with the opening of environmental test courses for industry operators, the expansion for consulting support projects of the defense industry support system is needed.

Purpose: This paper presents an application of Markov Process to reliability and availability analysis. In order to do that of analysis, we set up a specific case of Tablet PC and it's usage scenario. The case has it some spares and maintenance and repair processes. Methods: Different configurations of the tablet PC and as well as their functions are defined. The system configuration and calculated failure rates of components are modeled from Windchill Quality Solution. Two models, without a spare and with spare, are created and compared using Markov Process. The Matlab numerical analysis is used to simulate and show the change of state with time. Availability of the system is computed by determining the time the system stays in different states. Results: The mission availability and steady-state condition availability in accordance with the mission are compared and the availability of the system with spares have improved availability than without spares. Simulated data shows that downtime of the system increased which results in greater availability through the consideration of spares. Conclusion: There's many techniques and methods to do reliability and availability analysis and mostly are time-independent assumptions. But Markov Process, even though its steady-state and ergodic properties, can do time analysis any given time periods.

Purpose: The purpose of this study is to provide a sensitivity analysis of system reliability for recognizing effectiveness of changing of BD mode failures using reliability growth projection model based on NHPP. Methods: Crow extended reliability projection model (CERPM) is used to analyze the changing of two factors 1) the number of BD mode failures, 2) fix effectiveness factor (FEF) values. Results: The system reliability has increased in accordance with the number of BD mode failures and FEF values have increased. Conclusion: It is necessary to design failure modes and FEF values to supervise the reliability.

Purpose: We introduce ways to employ Markov chain model to evaluate the effect of preventive maintenance process. While the preventive maintenance process decreases the failure rate of each subsystems, it increases the downtime of the system because the system can not work during the maintenance process. The goal of this paper is to introduce ways to analyze this trade-off. Methods: Markov chain models are employed. We derive the availability of the system consisting of N repairable subsystems by the methods under various maintenance policies. Results: To validate our methods, we apply our models to the real maintenance data reports of military truck. The error between the model and the data was about 1%. Conclusion: The models developed in this paper fit real data well. These techniques can be applied to calculate the availability under various preventive maintenance policies.

Purpose: Recently, propensity score matching method is used in a large number of research paper, nonetheless, there is no research using fitness test of before and after propensity score matching. Therefore, comparing fitness of before and after propensity score matching by logistic regression analysis using data from 'online survey of adolescent health' is the main significance of this research. Method: Data that has similar propensity in two groups is extracted by using propensity score matching then implement logistic regression analysis on before and after matching separately. Results: To test fitness of logistic regression analysis model, we use Model summary, -2Log Likelihood and Hosmer-Lomeshow methods. As a result, it is confirmed that the data after matching is more suitable for logistic regression analysis than data before matching. Conclusion: Therefore, better result which has appropriate fitness will be shown by using propensity score matching shows better result which has better fitness.

Purpose: The purpose of this study is the analysis of the failure mechanisms effect of circuit design characteristics of the ballast for LED Lamp Methods: Recently, electronic circuit of ballasts for LED lamp are being occurred on various failure mechanisms (whiskers, ion migration, heat dissipation problem, switching element damage) because electronic ballast circuit design characteristics are becoming more and more diverse. Results: we analysis failure mechanisms that occurs in accordance with the circuit design characteristics The ballast for LED lamp were divided into three different types (Type A, Type B, Type C) considering circuit design characteristics (thermal design, PCB patten spacing, element material) and it was experimented in the acceleration test conditions ($85^{\circ}C$, 85% R.H). Conclusion: We confirmed that failure mechanism of the ballast for LED Lamp had occurred differently in accordance with the circuit design characteristics.

Purpose: The purpose of this research is to improve the reliability of the composite material blades used for the wind power generator, by applying the phased array ultrasonic testing technique out of the many nondestructive test into the blades. Method: The wind power generation composite blades are used, as a case study, in order to evaluate the reliability of the phased array ultrasonic testing technique. Defects that are most likely occurred in the field are injected into the different locations of the three different types of artificial test pieces and then phased array ultrasonic testing technique are applied to evaluate the reliability of its effectiveness. Result: As a result of the analysis of the defect signals by applying the A scan and B scan simultaneously, depth and width of the defect could be obtained. An area of defect was proportional to the amount of energy by color in B scan image. The larger amount of energy, reflected amount of energy was appeared in the order of red, orange, yellow, blue color. Conclusion: The most reliable testing method to detect the defect in composite blades for wind power generation is considered to be the combination of the other destructive testing technique with the phased array ultrasonic testing since the PAUT alone could not detect all range of the defects in the blades.

Purpose: With the advance of miniaturization of electronic products, stacked packages of high density semiconductors are commonly used. Potential failure modes and mechanisms of stacked packages are identified. Methods: Failure modes and mechanisms of thin chip stacked packages are determined through the categorization and failure analysis: delamination, non-wet, crack, ESD, EMI and the process related damages. Results: Those failure modes are not easy to find and require excessive amount time and effort for analysis and subsequent improvement. Conclusion: In this study, a method of estimating the failure rate based on the strength measurement is suggested.

Purpose: The purpose of this study is to propose efficiency of equipment testing the luminance degradation of OLED. Methods: The degradation model of Exponential model and Stretched exponential model is analyzed by goodness of fit test using calculated R-square. The degradation model having the higher R-square is finally selected. Scale parameter and Shape parameter using the selected degradation model is estimated. The activation energy and current density n using peck model among the accelerated model is estimated. the estimated parameters are analyzed by t-test. Results: The results of t-test show that the estimated parameters on chamber and hotplate are equal statistically. we can know the similarity of the luminance degradation rate and degradation pattern on chamber and hotplate. Conclusion: The result of the degradation test on chamber and hotplate is similar. when the accelerated degradation test on the panel of the OLED TV is performed, hotplate is requiring less samples, time and cost than chamber. so the accelerated degradation test on the panel of the OLED TV using the hoplate is efficient of time and cost.