• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.1
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• pp.52-61
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• 2016

To inject huge amount of $CO_2$ for CCS application, high pressure pipeline transport is accompanied. Rapid depressurization of $CO_2$ pipeline is required in case of transient processes such as accident and maintenance. In this study, numerical analysis on the depressurization of high pressure $CO_2$ pipeline was carried out. The prediction capability of the numerical model was evaluated by comparing the benchmark experiments. The numerical models well predicted the liquid-vapor two-phase depressurization. On the other hands, there were some limitations in predicting the temperature behavior during the supercritical, liquid phase and gaseous phase expansions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1325-1330
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• 2010

The breakdown of any critical component of a turbine results in the outage of power plants. Unexpected failure decreases equipment utilization and causes enormous economic losses. Currently, we conduct conservative preventive maintenance for a maintenance period that is proposed by a vendor. In the rapidly changing business environment, reliability-based maintenance is required in order to remain competitive and reduce maintenance costs while maintaining the reliability of equipment. In order to determine an appropriate maintenance period for guaranteeing reliability, we must determine the failure probability by carefully analyzing the failure history of the equipment. In this study, we created a database of failure history for power-plant turbines, predicted the best repair time using the Weibull function, and investigated how the appropriate maintenance cycle can be determined.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.388-391
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• 2008

The Domestic housing Industry has to give consequence to the redevelopment and rebuilding of existing housings rather than the supply by developing a new building site, and now those tendencies are rapidly spreading out. Also, because apartment buildings occupies 50% over of the existing housing, its maintenance, repair, remodeling and reconstruction got to be necessary area for the slumming prevention of a residential area and the disaster prevention occurred by durability lowering of the building. It is increasing the interest for reusing and recycling of C&D waste. The government is doing efforts to diminish amount of C&D waste. But there couldn't find any efforts for developing Integrated system to manage and to estimate lightly generated amounts of C&D waste. So, this study presents a integrated computer system that can estimate easily quantity of C&D waste by using CAD draw and 3D Object.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.116-121
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• 2012

The construction of underground structures such as box culverts for electric power transmission is increasing more and more, and the life extension of these structures is very important. Carbonation-induced corrosion in concrete may often occur in a high carbon dioxide environment. In this study, the risk of carbonation of two concrete box culverts in an urban area was evaluated by measuring the carbonation rate and concrete cover depth. Then, the carbonation-free service life at the depth of the steel was calculated, based on in situ information, by the Monte Carlo simulation. The service life of box culvert due to carbonation was estimated over 250 years via Monte Carlo simulation.

• Journal of Korea Water Resources Association
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• v.36 no.1
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• pp.45-59
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• 2003

The method in this study, which is more efficiency than the existing method, propose the optimal rehabilitation model based on the deterioration prediction of the laying pipe by using the deterioration survey method of the water distribution system. The deterioration prediction model divides the deterioration degree of each pipe into 5 degree by using the probabilistic neural network. Also, the optimal residual durability is estimated by the calculated deterioration degree in each pipe and pipe diameter. The optimal rehabilitation model by integer programming base on the shortest path can calculate a time and cost of maintenance, rehabilitation, and replacement. Also, the model is divided into budget constraint and no budget constraint. Consequently, the model proposed by the study can be utilized as the quantitative method for the management of the water distribution system.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.1
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• pp.155-160
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• 2019

In this paper, we propose an efficient grid-independent ESS control system through the control of renewable energy and agricultural ICT by utilizing the prediction of energy production and consumption. The proposed system is an integrated management system that can perform maintenance and monitoring by visualizing the accurate phase and data of power system. It can automatically cope, collect, process, and control the data. Also, it can analyze the power generation of solar power generation, consumption pattern of installed facilities, and operation trend of facilities. Further, it can predict the consumption of energy production and present the optimal energy management method by using the OpenAPI of the Korea Meteorological Administration, thereby reducing unnecessary energy consumption and operating cost.

• KNOM Review
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• v.24 no.1
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• pp.1-12
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• 2021

VM (Virtual Machine) live migration is a server virtualization technique for deploying a running VM to another server node while minimizing downtime of a service the VM provides. Currently, in cloud data centers, VM live migration is widely used to apply load balancing on CPU workload and network traffic, to reduce electricity consumption by consolidating active VMs into specific location groups of servers, and to provide uninterrupted service during the maintenance of hardware and software update on servers. It is critical to use VMlive migration as a prevention or mitigation measure for possible failure when its indications are detected or predicted. In this paper, we propose two VNF live migration methods; one for predictive load balancing and the other for a proactive measure in failure. Both need machine learning models that learn periodic monitoring data of resource usage and logs from servers and VMs/VNFs. We apply the second method to a vEPC (Virtual Evolved Pakcet Core) failure scenario to provide a detailed case study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1D
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• pp.73-81
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• 2008

Hereafter, the domestic housing industry has to give consequence to the redevelopment and rebuilding of existing housings rather than the supply by developing a new building site, and now those tendencies are rapidly spreading out. Also, because apartment buildings occupies 50% over of the existing housing, its maintenance, repair, remodeling and reconstruction got to be necessary area for the slumming prevention of a residential area and the disaster prevention occurred by durability lowering of the building. Accordingly, C&D waste is rising largely by reason of demolition works in city is increasing. The right management of C&D waste is being one of very important things, but little research has been conducted to estimate correctly C&D waste. In this study is to suggest standard units of C&D waste which can estimate demolition quantity of apartment. This units can estimate easily and correctly C&D waste in demolition works, also can possible use very important material to carry out policy of national waste management.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.6
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• pp.525-533
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• 2016

The purpose of current tunnel maintenance system in South Korea is safety-based maintenance system for accident prevention, So it is difficult to conduct a strategic maintenance. The development of a new maintenance system can lead to effective investment of limited financial and it's effort is still in progress. In this study, to develop a performance-based assessment method, indexes for assessment are derived taking into account the safety, durability and serviceability. The indexes for performance-based assessment were selected by a literature analysis and a delphi survey. Then the importance among indexes were calculated by the AHP analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.77-85
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• 2020

Currently, life-cycle cost analysis methods are introduced to maintain large infrastructure facilities in Korea. However, there are not many cases in which maintenance models are applied that reflect conditions such as the location of a facility and its surroundings. In order to establish an appropriate maintenance strategy, a cost prediction, deterioration model, and a decision model reflecting uncertainty should be established. In this study, an economic analysis model was developed for long-term cost planning and management based on user decisions based on maintenance methods and judgment criteria for painting specifications applied to power generation structures. The performance of the paintwork was assessed through the paint deterioration test for the application of the economic analysis model, and the results of the economic analysis according to the applied paint specifications (Urethan, polysiloxane, fluorine) were verified by applying the proposed economic analysis model. In this study, it is believed that the selection of the repair cycle and evaluation methods applied with the development model rather than the performance of the painting can be expected to be used as basic data for the maintenance cycle, even if it is not limited to the painting.