• 한국신뢰성학회지:신뢰성응용연구
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• 제13권1호
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• pp.45-53
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• 2013

In this paper, we analyze the failure mechanism of the washer pump to find what is the failure cause in the road environment. The statistics show the field common failure mode is inner corrosion. The failure mechanism is assumed that the inner part of washer pump is corroded due to inflow of moisture through vent hole. To prevent the failure, we can think a method that is covering the vent hole. In general, the vent hole is designed to play an important role in an automobile parts. So, we need to prove the vent hole is not necessary. The first purpose of this paper is to make sure that the vent hole does not affect the durability of washer pump using the analysis of operating condition. The second purpose is to compare the durability properties if the vent hole is covered.

• 한국태양에너지학회 논문집
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• 제37권5호
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• pp.1-11
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• 2017

A study on Nacelle Lidar (Light detection and ranging) measurement error and the data reliability verification was carried out at Haengwon wind farm on Jeju Island. For measurement data error processing, the characteristics of Nacelle Lidar measurements were analyzed by dividing into three parts, which are weather conditions (temperature, humidity, atmosphere, amount of precipitation), mechanical movement (rotation of wind turbine blades, tilt variation of Nacelle Lidar) and Nacelle Lidar data availability. After processing the measurement error, the reliability of Nacelle Lidar data was assessed by comparing with wind data by an anemometer on a met mast, which is located at a distance of 200m from the wind turbine with Nacelle Lidar. As a result, various weather conditions and mechanical movement did not disturb reliable data measurement. Nacelle Lidar data with availability of 95% or more could be used for checking Nacelle Lidar wind data reliability. The reliability of Nacelle Lidar data was very high with regression coefficient of 98% and coefficient of determination of 97%.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.48-54
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• 2018

The hydraulic servo actuator has always operated very precisely with high frequency and small displacement, and is used continuously for a long time. The hydraulic servo actuator of the test equipment used in the accelerated life test in order to guarantee the service life of the automotive parts failed earlier than the products before finishing the test. This study performed an analysis on the cause of the failure of the hydraulic servo actuator used in the test equipment, changed the design of the actuator to solve the root cause of the main failure mode, and developed the improved servo actuator. Based on above process, this study established a better performances and longer lifetime of the servo actuator after testing.

• 전력전자학회논문지
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• 제27권3호
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• pp.221-227
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• 2022

The reliability improvement of PV systems is an important factor in reducing the cost of PV energy because it is closely related to the annual energy production as well as the maintenance cost of PV systems. The reliability of PV inverters plays a key role in the reliability of PV systems because it is regarded as one of the most reliable critical parts of PV systems. The lifetime evaluation of PV inverters considering the mission profile in the design phase plays an important role in reliability design to ensure the required lifetime of PV inverters. In this paper, the lifetime of representative single-phase T-type and I-type NPC inverters are comparatively evaluated by considering the mission profile of a PV system recorded at Iza, Spain. Furthermore, the effect of the pulse width modulation methods on the lifetime is also discussed. The lifetime evaluation of PV inverters is performed at the component-level first and then the system level by considering all power devices.

• 대한안전경영과학회지
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• 제25권1호
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• pp.15-21
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• 2023

In modern society, the delivery service market has grown explosively due to rapid changes in social structure and the recent COVID-19 pandemic. Therefore, various problems such as injury to workers and an increase in human accidents are occurring due to the loading and unloading of parcels. In order to solve this problem, domestic company n is developing a "robot-based cargo loading and unloading system". In developing a new technology system, quantitative reliability targets should be set for efficient operation and development. In this paper, reliability analysis was conducted through field data for the pneumatic gripper of the "robot-based cargo loading system". The reliability of the failure data was analyzed to estimate the distribution parameters and MTTF. Random data was derived for the probability of occurrence of a failure with the estimated value. By repeating the simulation to predict the number and year of failures according to the estimated parameters of the probability distribution, it was proposed as a method that reflects realistic probabilities rather than calculating with simple arithmetic using the average MTTF previously used in the field.

• 해양환경안전학회지
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• 제8권1호
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• pp.127-137
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• 2002

This paper deals with developing a Web-based Solver NRO(Network Reliability Optimizer) for solving three classes of reliability redundancy optimization problems which are generated in series systems. parallel systems and complex systems. Inputs of NRO consisted in four parts. that is, user authentication. system selection. input data and confirmation. After processing of inputs through internet, NRO provides conveniently the optimal solutions for the given problems on the Web-site. To alleviate the risks of being trapped in a local optimum, HH(Hybrid-Heuristic) algorithm is incorporated in NRO for solving the given three classes of problems, and moderately combined GA(Genetic Algorithm) with the modified SA(Simulated Annealing) algorithm.

• 한국안전학회지
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• 제30권3호
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• pp.114-122
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• 2015

In a fire hazard analysis (FHA) for nuclear power plant, various electrical circuit analyses are performed in the parts of fire loading analysis, fire modeling analysis, separation criteria analysis, associated circuit analysis, and multiple spurious operation analysis. Thus, electrical circuit analyses are very important areas so that reliability of the analysis results should be assured. This study is to establish essential electrical elements for each analysis for verification of the reliability of the electrical circuit analyses in the fire hazard analysis for nuclear power plants. Applying the results derived by the study to domestic nuclear power plants, it is expected to determine the adequacy of the fire hazard analysis report and contribute to the reliability of the fire hazard analysis of those plants.

• 정보처리학회논문지C
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• 제15C권3호
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• pp.199-204
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• 2008

CAN은 처음에는 차량 네트워크에서의 사용을 위해 고안되었으나 잡음에 강하고 신뢰성이 높아 공장자동화 등에서도 많이 사용되고 있다. 그러나 1:1통신에서 네트워크 기반의 통신방식으로 변화되면서 각 장치의 기계적인 동작뿐만 아니라 전자, 소프트웨어적인 동작에 대해서도 철저한 검증이 필요하게 되었다. 본 논문은 CAN 기반 시스템에서 통신의 신뢰성을 데이터의 정확성에 대한 부분과 시간상의 정확성에 대한 부분을 검증하는 방법을 제시하고 있다.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2009년도 춘계학술대회
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• pp.153-165
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• 2009

It is hot issue to get the competitiveness of product through reliability-growth as well as availability and safety in almost high-technology industry including military, chemistry, nuclear, telecommunication, transportation service and so on. In advanced countries, they experienced remarkable growth based on reliability technology in materials&parts industry as well as high-tech industry. It has become a symbol of national competitiveness and created a higher value added. This paper is taking on effectively developing ways to deploy IEC 60300 dependability management system and the base technology that are needed to improve competitiveness of industries in Korea.

• Corrosion Science and Technology
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• 제11권5호
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• pp.179-183
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• 2012

As one of promising solutions to overcome high oil price and energy crisis, the construction market of high value-added LNG plants is spotlighted world widely. The purpose of this study is to introduce LNG-RBI system to develop risk assessment technology with RAM(Reliability, Availability, Maintainability) modules against overseas monopolization. After analyzing relevant specific features and their technical levels, risk assessment program, non-destructive reliability evaluation strategy and safety criteria unification class are derived as core technologies. These IT-based convergence technologies can be used for enhancement of LNG plant efficiency, in which the modular parts are related to a system with artificial optimized algorithms as well as diverse databases of facility inspection and diagnosis fields.