• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.41-47
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• 2012

There are PFD(Process Flow Diagram) and P&ID(Piping and Instrument Diagram) for designing and managing chemical process efficiently. They provide the operation condition and equipment specifications of chemical process, but they do not provide the reliability of chemical process. Therefore, in this study, Reliability Flow Diagram(RFD) which provide the cycle and time of preventive maintenance has been developed using Directed Graph Analysis methodology. Directed Graph Analysis methodology is capable of assessing the reliability of chemical process. It models chemical process into Directed Graph with nodes and arcs and assesses the reliability of normal operation of chemical process by assessing Directed Graph sequential. In this paper, the chemical process reliability transition according to operation time was assessed. And then, Reliability Flow Diagram has been developed by inserting the result into P&ID. Like PFD and P&ID, Reliability Flow Diagram provide valuable and useful information for the design and management of chemical process.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.465-470
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• 2011

Recently fault currents are increasing in a network. It is caused by increase in electric demand and high penetration of distributed generation with renewable energy sources. Moreover, distribution network has become more and more complex as mesh network to improve the distribution system reliability and increase the flexibility and agility of network operation. Accordingly, the fault current will exceed capacity of circuit breakers soon and all the various rational solutions to solve this problem are taken into account. Under these circumstances, superconducting fault current limiter(SFCL) is a new alternative in the viewpoint of technical and economic aspects. This study presents operation processes for a resistive-type of SFCL, and it proposes reliability model for the SFCL. When a SFCL is installed into a network, the contribution of decreased fault currents to failure for distribution equipments can be quantified. As a result, it is expected that a SFCL makes the reliability of adjacent equipments on existing network improve and these changes are analyzed. We propose a methodology to evaluate the reliability in the distribution network where a SFCL is installed considering a reliability model for resistive-type of SFCL and reliability changes for adjacent equipments which are proposed in this paper.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.119-120
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• 2020

In order to establish an evaluation method that can quantitatively evaluate the fire safety of existing buildings in Korea, a stochastic approach is needed to consider the extent of damage in the event of actual fire, along with the operation and installation of facilities. Accordingly, as a basic study for the establishment of fire safety assessment methods for buildings, this study aims to analyze the results of safety inspection and the degree of damage caused by the operation of fire doors and fire shutters in order to derive the reliability of fire doors and fire shutters. As a result, the results of inspection of fire shutters and fire doors and the results of operation using fire statisticians are as follows. As a result of the inspection, the positive rate of fire doors was about 82% and 98% of normal operation was derived from the fire investigation.

• KIEE International Transactions on Power Engineering
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• v.5A no.1
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• pp.9-15
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• 2005

In the operation of distribution systems, DGs (Distributed Generations) are installed as an alternative to extension and the establishment of substations, transmission and distribution lines according to the increasing power demand. In the operation planning of DGs, determining optimal capacity and allocation achieves economical profitability and improves the reliability of power distribution systems. This paper proposes a determining method for the optimal number, size and allocation of DGs in order to minimize the operation costs of distribution systems. Capacity and allocation of DGs for economical operation planning duration are determined to minimize total cost composed with power buying cost, operation cost of DGs, loss cost and outage cost using the GA (Genetic Algorithm).

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.6
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• pp.112-123
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• 2017

The accurate forecasting of the public transportation's transit and arrival time has become increasingly important as more people use buses and subways instead of personal vehicles under the government's public transportation promotion policy. Using bus management system (BMS) data, which provide information on the real-time bus location, operation interval, and operation history, it is now possible to analyze the bus schedule reliability. However, the punctuality should always be considered together with the operation safety. Therefore, this study suggests a new methodology to secure both reliability and safety using the BMS data. Unlike other studies, we calculated the bus travel time between two bus stops by dividing the total travel length into 6 sections using 5 different measuring points. In addition, the optimal travel time for each bus route was proposed by analyzing the mean, standard deviation and coefficient of variation of the each section's measurement. This will ensure the reliability, safety and mobility of the bus operation.

• Journal of Applied Reliability
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• v.8 no.2
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• pp.61-73
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• 2008

Reliability program in one of the most efficient tools for cost saving during the acquisition process including alternatives for design configurations, operation concepts, maintenance concepts. Industrial reliability centers have already equipped with infrastructure such as reliability standards, reliability apparatus. In this study revitalizing plans are proposed to apply industrial reliability technology to national defense technology.

• Proceedings of the Korean Reliability Society Conference
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• 2004.04a
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• pp.15-25
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• 2004

Inherent reliability depends on decisions made during design and manufacture. Reliability degrades with age and production rate (or usage level/intensity). System design based on some nominal production rate. Actual production rate can differ-depends on commercial considerations.(omitted)

• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.195-202
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• 2002

The primary objective of Supply Chain Management (SCM) is to optimize the cash, material and information flow for satisfying customer demands through coordinating the relationship between Supply Chain components such as suppliers, manufacturers, and inventories, etc. By Supply Chain Planning (SCP), operation tasks or goals, should be done in specific due date, are ordered to each SC component for achieving such objective. However, the achievement for operation tasks or goals is affected by uncertainties in SC. In general, reliability theory Is explained as the probability that a product or system will perform its specified function under prescribed conditions without failure for a specified period of time. Therefore, the reliability of SC can be defined as the probability that SC will satisfy customer demands until the specific due date. In this paper, a basic framework to evaluate reliability is respectively proposed as supply chain components, and then a overall framework to estimate the reliability for SC is also proposed.

• Journal of the Korean Society of Systems Engineering
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• v.5 no.1
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• pp.43-48
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• 2009

Korean Tilting trains have been tested on conventional lines since the beginning of 2007 for evaluating its reliability. We achieved some major performance tests which are the maximum operation speed, 180km/h test and the maximum curves increasing speed, over 30 percentage comparing with non-tilling operation train. In order to analysis reliability data of tilting train, we have used the special system engineering frame with interfacing between component suppliers effectively. And also we have developed the data aquisition system which consists of monitor, sensors and depot computer etc. As a results of calculation, until now we realized that the reliability are getting more increasing than starting point of running field test.

• Nuclear Engineering and Technology
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• v.29 no.6
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• pp.433-443
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• 1997

In this work, an analytic approach to the dependability of software in the operational phase is suggested with special attention to the hardware fault effects on the software behavior : The hardware faults considered are memory faults and the dependability measure in question is the reliability. The model is based on the simple reliability theory and the graph theory which represents the software with graph composed of nodes and arcs. Through proper transformation, the graph can be reduced to a simple two-node graph and the software reliability is derived from this graph. Using this model, we predict the reliability of an application software in the digital system (ILS) in the nuclear power plant and show the sensitivity of the software reliability to the major physical parameters which affect the software failure in the normal operation phase. We also found that the effects of the hardware faults on the software failure should be considered for predicting the software dependability accurately in operation phase, especially for the software which is executed frequently. This modeling method is particularly attractive for the medium size programs such as the microprocessor-based nuclear safety logic program.