• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4186-4192
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• 2012

Because wind turbines are larger and more off-shore construction due to economic and environmental factors, it is more difficult to access the wind turbine as well as the necessary parts and the maintenance costs are increasing. So, we need to minimize fault elements and to prevent a secondary accident at failure through monitoring to reduce maintenance costs and to increase reliability of operation. In this paper we have implemented ZigBee based wireless sensor nodes and network for wind turbine condition monitoring using temperature, humidity, voltage, current, wind direction, and wind speed sensors. ZigBee wireless sensor nodes signals are transmitted to a central monitoring system via routers. Also, the sensor signals are collected and processed using LabVIEW program to monitor the wind turbine conveniently. The administrators and users can monitor the condition of wind turbine at remote site in real time over TCP/IP.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.5
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• pp.95-100
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• 2009

The water purification systems have been hardly used for agricultural purpose due to their complicated compositions and high costs for farmers, while only simple filtrations have been applied to irrigation systems in order to prevent the system from clogging problems. This study therefore developed a clean water supplying system, the Filter-Disinfection-Adsorption (FDA) system, especially for greenhouse cultivation of where low quality of water is available. This system has also been produced for providing convenience water to farmers in the areas of no water supply service systems for the purpose of washing their bodies or agricultural machineries after farm work. The FDA system consists of three stages of purification processes with an integral module, including disk and teflon filtrations and Ultraviolet (UV) sterilization processes. Indoor experiments were undertaken with a trial product of the FDA system to test its performance. The operation test of the process was performed as well as the condition check of each item including UV module, filters, control panel, pump, valves, etc. The results shows good performance of each test with no critical problems. The initial and maintenance costs were also analysed with other purification systems. From the comparisons, the FDA system found to be very economical and easy to use.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1279-1287
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• 2009

An increasingly competitive business environment has been concentrated on industries to reduce the operating costs. Industries such as gas, oil, petrochemical, chemical, and electric power have employed for the operation and used for large equipment or structures that require a high capital investment. In order to meet these requirements, the industries are increasingly moving toward saving the experimental verification and computer simulation. Therefore industries to reduce the maintenance costs without compromising the operational safety have been forced on finding for better and more efficient methods to inspect their equipment and structures. In this study, it focused on the development the real-time non-contract monitoring system as an efficient tool for the experimental study of weld defects based on the relationship between the measured voltage and input parameters.

• Convergence Security Journal
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• v.16 no.6_1
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• pp.67-74
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• 2016

The development of weapon systems that look only be introduced as a huge budget directly related to combat rea diness. If we develop the expensive equipment it will not be the same state or have to wait a lot of time in mainten ance facilities for maintenance, which will have a profound impact on the exercise Efficiency. In order to solve this problem, the operation and use state of the weapon system requires effort to successfully p erform the duties held by the defined and assigned, Further analysis should be conducted RAM in order to reduce m aintenance manpower and logistic support costs. The role of business is to increase the RAM system reliability by L ee to Fig system failure rate from the development and maintenance, and reduced life cycle costs. Therefore, the present study was to determine the RAM to perform analysis procedures and methods and limita tions of each element, such as to maximize the effectiveness of comprehensive logistics support and help to study to become an effective logistics support.

• Journal of Power Electronics
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• v.13 no.5
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• pp.737-745
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• 2013

Offshore wind farms are rapidly growing owing to their comparatively more stable wind conditions than onshore and land-based wind farms. The power capacity of offshore wind turbines has been increased to 5MW in order to capture a larger amount of wind energy, which results in an increase of each component's size. Furthermore, the weight of the marine turbine components installed in the nacelle directly influences the total mechanical design, as well as the operation and maintenance (O&M) costs. A reduction in the weight of the nacelle allows for cost-effective tower and foundation structures. On the other hand, longer transmission distances from an offshore wind turbine to the load leads to higher energy losses. In this regard, DC transmission is more useful than AC transmission in terms of efficiency because no reactive power is generated/consumed by DC transmission cables. This paper describes some of the challenges and difficulties faced in designing high-power-density power conversion systems (HPDPCSs) for offshore wind turbines. A new approach for high gain/high voltage systems is introduced using transformerless power conversion technologies. Finally, the proposed converter is evaluated in terms of step-up conversion ratio, device number, modulation, and costs.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.1-8
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• 2019

Modern weapon systems are multifunctional, with capabilities for executing complex missions. However, they are required to be highly reliable, which increases their total cost of ownership. Because it is necessary to produce the best results within a limited budget, there is an increasing interest in development, acquisition, and maintenance costs. Consequently, there is a need for tools that calculate the lifecycle costs of weapons systems development to facilitate decision making. In this study, we propose a cost calculation function based on the Markov process simulator-a reliability, availability, and maintainability analysis tool developed by applying the Markov-Monte Carlo method-as an alternative to these requirements to facilitate decision-making in systems development.

• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.896-904
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• 2017

Several Generation IV nuclear reactor concepts have goals for optimizing investment recovery through phased introduction of multiple units on a common site with shared facilities and/or reconfigurable energy conversion systems. Additionally, small modular reactors are suitable for remote deployment to support highly localized microgrids in isolated, underdeveloped regions. The long-term economic viability of these advanced reactor plants depends on significant reductions in plant operations and maintenance costs. To accomplish these goals, intelligent control and diagnostic capabilities are needed to provide nearly autonomous operations with anticipatory maintenance. A nearly autonomous control system should enable automatic operation of a nuclear power plant while adapting to equipment faults and other upsets. It needs to have many intelligent capabilities, such as diagnosis, simulation, analysis, planning, reconfigurability, self-validation, and decision. These capabilities have been the subject of research for many years, but an autonomous control system for nuclear power generation remains as-yet an unrealized goal. This article describes a functional framework for intelligent, autonomous control that can facilitate the integration of control, diagnostic, and decision-making capabilities to satisfy the operational and performance goals of power plants based on multimodular advanced reactors.

• Smart Structures and Systems
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• v.32 no.5
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• pp.309-318
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• 2023

The appropriate maintenance of highway roads is critical for the safe operation of road networks and conserves maintenance costs. Multiple methods have been developed to investigate the surface of roads for various types of cracks and potholes, among other damage. Like road surface damage, the condition of expansion joints in concrete pavement is important to avoid unexpected hazardous situations. Thus, in this study, a new system is proposed for autonomous expansion joint monitoring using a vision-based system. The system consists of the following three key parts: (1) a camera-mounted vehicle, (2) indication marks on the expansion joints, and (3) a deep learning-based automatic evaluation algorithm. With paired marks indicating the expansion joints in a concrete pavement, they can be automatically detected. An inspection vehicle is equipped with an action camera that acquires images of the expansion joints in the road. You Only Look Once (YOLO) automatically detects the expansion joints with indication marks, which has a performance accuracy of 95%. The width of the detected expansion joint is calculated using an image processing algorithm. Based on the calculated width, the expansion joint is classified into the following two types: normal and dangerous. The obtained results demonstrate that the proposed system is very efficient in terms of speed and accuracy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.742-746
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• 2008

With the trend of factory automation, nowadays, much industrial machinery tends to be put into 24-hours operation a day. However, these trends in industrial equipments also increase the possibility of various mechanical problems and bring about innumerable maintenance cost. There is a strong need of the condition monitoring and diagnosis for industrial equipment, especially rotating machinery, since they are connected not only to the reduction in the maintenance costs but also connected to the enhancement of production efficiency. Generally, to evaluate the operating conditions in the machinery in the industrial field, various physical properties are monitored. Among them, vibration and Noise signals are the mist important indicator and it is effectively used in many diagnosis systems for machinery. Much previous research is based in the FFT (Fast Fourier Transform) method. The spectral analysis is assumed that the signal is stationary. However, almost random signals are non-stationary. The wavelet transform has been recognized an efficient Method. Most interesting sounds have time-varying features. Signal processing techniques for the analysis of transient sound have been not clearly given yet.

• Korean Journal of Construction Engineering and Management
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• v.16 no.2
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• pp.29-37
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• 2015

Multi-household buildings are efficiently maintained from the mid- and long-term viewpoint according to the long-term repair coverage system etc. On the other hand, public buildings are not systematically maintained due to a lack of past maintenance cost data and inefficient budget plans, among other problems. Targeting public buildings in Incheon, this study analyzed operation costs variables. To verify the analysis results, they underwent a correlation analysis and a multi-regression analysis. With regard to public buildings electricity, gas and tap water cost, the influence power of the served life, floor area, and workforce were analyzed, revealing that electricity cost was highly correlated with workforce, while gas and tap water cost were correlated with tap water cost. Also, the correlation analysis results were verified through a multi-regression analysis, and a maintenance cost estimation model was presented using a regression equation.