• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.396-398
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• 2006

Predictive maintenance is not an unfamiliar concept because it has been used to predict the failures of electrical equipment such as transformers, motors and so on. By thoroughly monitoring the status of individual equipment and tracing how the various characteristics change over time, we can be aware of its exact condition and prevent the impending failure by taking appropriate actions. In this paper, I will extend the concept of predictive maintenance for individual electrical equipment to the power distribution system and show how to use the data obtained from power quality monitors to improve the power system.

• International Journal of Railway
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• v.9 no.2
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• pp.27-35
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• 2016

In spite of recent advances in ballasted railway track, the correct choice of ballast for rail track is still considered critical because aggregates progressively deteriorate under traffic loading and environmental exposures. Various ballast requirements, functions and duties have been defined by researchers, railway companies and countries' regulations even though it needs to be integrated to make following proper decision during track operation and maintenance. A proper understanding of ballast properties and suitable tests are prerequisites for minimizing maintenance costs. This paper presents a capable classification for ballast characteristics which need to be investigated beforehand to such a way, firstly to assign ballast functions, secondly need to clarify ballast requirements, thirdly to map appropriate tests to evaluate ballast characteristics and then it must be such that if ballast cannot carry out one of these duties, be able to call there is ballast defect. The paper is structured in order to achieve these objectives.

• Journal of Korean Society of Rural Planning
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• v.8 no.2 s.16
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• pp.50-56
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• 2002

In 1980s, studies on the river environment and the management techniques to maintain the quality of water achieved actively. From the beginning of 1990s, the concept considering the river ecology and conservation in urban area have been introduced in Korea. Recently, some environment friendly projects on the rivers have been executed and some are under way. Many small rivers in rural areas have been maintained considering landscape and partly ecology. However until the pilot project named Songsam drainage channel project started in 1998, there were no studies and projects on the irrigation and drainage channels considering environment friendly maintenance. Korea Agricultural and Rural Infrastructure Corporation (KARICO) is going to introduce environment friendly and naturally favorable maintenance technique when the new projects to reform the irrigation and drainage channels are planned. Irrigation channel in O-dong project site in Yeomsan-myeon, Younggwang-gun was designed considering environment friendly consolidation and maintenance.

• Journal of the Semiconductor & Display Technology
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• v.11 no.4
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• pp.1-6
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• 2012

Keeping the polarization direction of the projection light unchanged is of crucial importance for high quality of images on a double-screen 3D projection display system. It has been found that the deposition of oxide layers on the surfaces of scattering polarizer film results in an improvement of polarization maintenance property of the film. The secondary image formed on the front screen by the light scattered from the rear screen decreases by 30% through the application of oxide layers on both surfaces of the screen. Since the oxide layer can also be used as an anti-reflection (AR) coating of the film, this method is very effective for the projection display applications.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.236-237
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• 2015

Concrete is the one of the most widely used in every country as a structural materials. On the other hand, a lot of fire incident has been occurred all over the world. But maintenance methods such as inspection and diagnostic methods, design methods, quality control methods for the purpose of improving the performance of concrete structures damaged by fire has made in its own way. Therefore, the purpose of this proposal of new working item is is to ensure the safety of the concrete structures damaged by fire in the field of assessment of damage, design, repair methods and so on through the International Organization for Standardization.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.1
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• pp.113-120
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• 1999

Due to the heterogeneous nature of a concrete, periodic inspections are compulsory to maintenance of quality of concrete structures. The major object of this study is to analyze and investigate experimentally the experimental equation for the estimate of compressive strength of prestressed concrete. In this study, surface hardness method, ultrasonic method are investigated to evaluate strength of concrete specimens. Specimens are cast in laboratory and cores are cut from specimens in order to estimate the accurate strength. These values are used to compare with calculated values from test data. The result shows that the proposed equation can reproduce the results at prestressed concrete beam girders more appropriately than previous equations.

• International Journal of Reliability and Applications
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• v.2 no.1
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• pp.57-71
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• 2001

Global competition to increase production output and to improve quality is spurring manufacturing companies to use condition monitoring and fault diagnostic systems for predictive maintenance. As monitoring, testing, and measuring techniques develop, predictive control of components and complete systems have become more practical and affordable. In this article, we will consider the computer based data acquisition system for condition monitoring and the condition parameter analysis techniques for fault detection and diagnostics in the machinery and briefly discuss reliability prediction and the limit value determination in condition monitoring.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1294-1302
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• 2008

Talk-Back systems comprised of master-equipment at the control room and slave-equipment at turnouts refer to the intercommunication facilities that optimize mutual communication between maintenance staff on trackside and the control room to facilitate quickness and accuracy of train operation control and its maintenance within depot and on mainlines with turnouts for direction switching of the trains in operation. The weakness lies in additional maintenance costs of cables since the Talk-Back system installed on line 1 along with line 2-4 has a profound effect on the voice quality leading to the attenuation and crosstalk of the system due to the deterioration of cables and environmental factors. This paper discusses the Talk-Back system in a radio communication environment with the application of RF(Radio Frequency) communication system from the wire communication system by cables to ameliorate these problems, and deals with the energy saving environmentally friendly facilities in consideration of replacing power section at salve-equipment with solar batteries benefitting the system in light of energy consumption.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.5
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• pp.59-66
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• 2017

Preeminent water treatment plans are essential to preserve the water quality of aquatic biotopes. Previous studies have not been sufficient to provide cost-effective maintenance method since they focused only on the purification of deteriorated water that requires a continuous supply of clean water. This study proposes an economical method of water quality maintenance using water treatment media block constructed vertically using porous ceramics, zeolite, and river pebble. The water treatment media block does not require a separate purification area because it functions as a purifier within the ecological pond which can maximize the biotope area. To evaluate the performance of the water treatment media block, we longitudinally tracked the change of water quality indicators (pH, TDS, COND, DO, T-P, T-N, COD) suggested by Water Environment Standards, Ministry of Environment, Republic of Korea. We compared the water quality of one control (A: general ecological pond composition method of the laminated structure) and two experimental groups (B: a combination of aquatic plants and a water treatment media block, C: a water treatment media block only). As a result, we confirmed that the water treatment media block is an efficient and economical method to maintaining the water quality of the ecological pond for a long time. The water treatment media block will be a great help in providing a better aquatic biotope space for aquatic insects and fishes living in clear water.

• Korean Journal of Poultry Science
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• v.7 no.1
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• pp.1-11
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• 1980

About 6 to 8% of the eggs annually produced are broken or cracked between the hen and the consumer's carton. The majority of this breakage is due to interrelationships between egg shell quality and the many biological, environmental and managerial factors which have been individually identified as affecting breakage. Some of the factors associated with shell damage discussed in this review include age of hens, temperature ana humidity of the laying house, design of the cage systems and of the cage floors, type of material used to manufacture the cages frequency of daily egg collection in the laying house and, Probably most important, the frequency and quality of handling equipment maintenance. Age and genetic constitution of the hens, environmental temperature, and design and quality of equipment maintenance are the major factors that influence shell breakage. There is a curvilinear relationship between shell quality and shell breakage which explains why small changes in shell quality may be associated with large changes in the incidence of breakage. Published data indicate the incidence of breakage may range from as low as 1 to 2% to 35% or more for other egg producers.