• Journal of Korean Society for Quality Management
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• v.49 no.3
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• pp.299-312
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• 2021

Purpose: We provide a condition-based maintenance policy where a surrogate variable is used for monitoring system performance. We constructed a risk function by taking into account the risk and losses accompanied with erroneous decisions. Methods: Assuming a unique degradation process for the performance variable and its specific relationship with the surrogate variable, the maintenance policy is determined. A risk function is developed on the basis of producer's and consumer's risks accompanied with each decision. With a strategic safety factor considered, the optimal threshold value for the surrogate variable is determined based on the risk function. Results: The condition-based maintenance is analyzed from the point of risk. With an assumed safety consideration, the optimal threshold value of the surrogate variable is provided for taking a maintenance action. The optimal solution cannot be obtained in a closed form. An illustrative numerical example and solution is provided with a source code of R program. Conclusion: The study can be applied to situation where a sensor signal is issued if the system performance begins to degrade gradually and reaches eventually its functional failure. The study can be extended to the case where two or more performance variables are connected to a same surrogate variable. Also estimation of the distribution parameters and risk coefficients should be further studied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.533-542
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• 2016

The periodic maintenance of bridges is necessary once they have been constructed and its cost depends on various factors, such as their condition, environmental conditions and so on. To make a decision support system, it is essential to establish a basic reconstruction cost model. In this study, a regression model is suggested for calculating the reconstruction cost for typical cases and influential factors, depending on the type of bridge and its components, by analyzing the basic bridge specifications based on the data of the Bridge Management System (BMS). The details for each case were estimated in consideration of the cost calculation variables. The details for each case were estimated in consideration of the cost calculation variables. The cost model for the new construction of the superstructure, substructure and foundation and the temporary bridge construction and demolition costs were drawn from the regression analysis of the estimation results of typical cases according to the cost calculation variables. The reconstruction costs for different types of bridge were obtained using the cost model and compared with those in the literature. The cost model developed herein is expected to be utilized effectively in maintenance decision making.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.1-9
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• 2004

Repair of concrete structures has been a focus of attention in recent years not only in Japan but also worldwide. Concrete structures have fallen short of expectations at the time of construction-they should have been perpetual and maintenance-free. However, investigation into their premature deterioration reveals the primary causes: Concrete was made using inadequate materials and/or inadequate mixture proportions due to insufficient consideration and was placed inadequately under insufficient execution control. The secondary causes include insufficient consideration at the time of construction for the environmental conditions to which the structures were to be exposed. In any event, in the current economic climate, structures cannot be demolished and rebuilt as soon as they are damaged, but instead are expected to continue to be in service as long as possible with appropriate repair or retrofitting. This paper analyzes the causes of deterioration requiring repair and introduces relevant repair techniques. At the end, the repair project of the Sanyo Shinkansen Line in which the author was involved through committee activities is reported.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.70-83
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• 2001

The required standards for environmental tests for communication and electronic equipment used currently in the army are not standards into which the Korean climate and use environment are taken into consideration. But the environmental testing standards of the U.S. army at the time of its establishment(MIL-STD-810) “A” version has been used without taking into consideration the Korean domestic situation and conditions by simply translating the US standards. Adherence to these standards may limit the ability to supply materials in case of emergency since the increase in the manufacturing costs according to excessively strict standards induces an increase in the acquisition cost of military equipment, unnecessarily high maintenance and repair expenses are consumed, and stocks of parts for the military use have to be retained at all times.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.3
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• pp.105-112
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• 2000

For the purpose of building up the construction prospects of highway in consideration of natural environment. The tree planting and flower seeding in highway road side using native species were offered to natural landscape and resting area landscaping for peoples, and these area were 194place. The tree planting and flower seeding activity is to improve driving circumstances, and to conserve living and natural environment along the highways. And, preparation of ecotone and biotope at the highway surroundings for natural ecosystem conservation is an important activity, and planting of natural plants is generally carried out near wildlife ecoroads in order to give the way for animals. The primary purpose of this tree planting and seeding is not only to reduce environmental pollution, but also to enhance the ecological surroundings of highway circumference. Ultimately, It is essential that the constructive method of highway think over such as ecological environment and road design, surveying and management, construction, highway maintenance etc.

• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.468-475
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• 2002

This paper reports on the friction characteristics of a piston ring pack with consideration of mixed lubrication. The analytical model is presented by using the average flow antral asperity contact model. The effect of operating condition, and design parameters on the MOFT, maximum friction force, and mean frictional power loss are investigated. Piston ring prick shows mixed and hydrodynamic lubrication characteristics. From the predicted results, it was fand that the ring tension and height of surface roughness have great influence on the frictional power losses in a ring pack. Especially, ring tension is a dominant factor for the reduction of friction loss and maintenance of oil film thickness.

• Journal of Information Technology Applications and Management
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• v.20 no.3
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• pp.1-18
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• 2013

Software architecture is the blueprint for a software system and should provide consistent guidelines for design, implementation, and maintenance throughout the entire lifecycle of the system. Components, interactions between the components, well-formed structure, reasons, and various perspectives reflecting various stakeholders' concerns changing through the phases of software lifecycle are the key elements of software architecture. The architect identifies and engages the stakeholders, understands and captures stakeholder's concerns including those regarding life cycle, and lets the concerns reflected in the architecture. To do so, architect should take into consideration various contextual elements regarding the system too. We make an extended list of the elements, especially those of business application software architecture, that the architect should take into consideration and construct a model of the relationships between the elements.

• Journal of KIBIM
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• v.5 no.4
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• pp.23-29
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• 2015

The purpose of this study is to provide considerations for developing reverse engineering guidelines for AEC(Architecture, Engineering and Construction). The reverse engineering is a methodology which has the purpose of extracting and recognizing geometries and properties from physical objects such as buildings, facilities, terrain and infrastructure including roads, bridges, and tunnels. To handle them for the purpose of construction management, maintenance, and operation, we should know the exact position, orientation, and dimension of the objects including their properties. As the viewpoint of the information extraction from reverse engineering, it is necessary to derive consideration factors for developing reverse engineering guidelines.

• Journal of the Korean Professional Engineers Association
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• v.44 no.4
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• pp.44-49
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• 2011

For the pleasant dwelling place, the most of apartments are designed with the increased green area ratio in ground space and the underground parking lot. However, the condensation in underground space has occasionally occurred due to the insufficient ventilation and insulation treatment. Despite reinforcement of the insulation treatment and mechanical ventilation for the preventing method of condensation. It seems difficult to expect preventing effects for the condensation without consideration of the thermal characteristic of structures. Furthermore, no fundamental measure has been established because maintenance work for these defects incurs a lot of costs and these defects could be occurred again. This study suggests a new method for preventing floor surface condensation through analyzing the reasons of condensation which occurred in the underground floor.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1364-1371
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• 2011

Advanced EMU completed a production of test train, composed of 6 cars, after 5 years of development process, and it is currently under the process of integrated test and evaluation to inspect performance of car system, efficiency of transport, safety, punctuality, energy efficiency in accordance with urban railways act at Daebul test line. Advanced EMU was produced under consideration of transportation capacity, maintainability, reliability, energy saving, convenience of passengers, and traffic-vulnerables, so it has an epochal difference from former EMU system. And advanced EMU assures operation management from manager's perspective and efficiency of maintenance for practicalization of car and individual equipment. This paper introduces each major equipment of advanced EMU which is based on many years of experience of management and maintenance.