• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.5
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• pp.121-132
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• 2009

The agency which is responsible for work related to the restoration of vegetation on the quarry in Hong Kong is the Geotechnical Engineering Office of Civil Engineering and Development Department (CEDD). CEDD's environmental management system was certified as ISO 14001 : 2004 in 2006 and diverse instructions and technical documents about the restoration of the quarry were published and used for the performance of work and the implementation of the project. The restoration of the quarry is being carried out to respond to short-term and long-term goals. The general instructions for the restoration of vegetation says that a plant, when selected, should be self-sustainable with minimum maintenance required, have a high growth and survival rate, be tall enough to cover the rock slope faces, and preferably produce colourful flowers. These instructions prescribe the vegetation introduction technology, planting seasons, structural material of the vegetation works, maintenance and management, tree nursery operation, means of water supply, etc. This report introduced the outline of work on restoring vegetation carried out at Anderson Road, Shek O, Lam Tei, Turret Hill, Lamma, all large-sized quarries. In addition, it additzed Anderson Road's master plan. It is hoped that the Hong Kong examples so introduced are referred to in terms of institutional and technical considerations related to the nation's project for restoring quarries.

• Journal of the Korea Society for Simulation
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• v.28 no.4
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• pp.1-10
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• 2019

The Sea Water Reverse Osmosis (SWRO) plant should take into account the availability of the plant from the design stage for long-term and continuous fresh water production. As it occurs, it is necessary to establish a corrective maintenance plan and preventive maintenance plan to maintain availability. In the field of complex engineering structures such as seawater desalination plants, it is difficult to estimate the reliability or availability of the system in a mathematical way. This study develops RAM analysis framework and model, and proposes discrete event simulation model as a application sowtware specialized for seawater desalination plant. Considering the characteristics of the plant maintenance, in case of corrective maintenance, we propose a preventive maintenance policy that not only repairs or replaces a single-broken part, but also simultaneously maintains all accessible parts according to the level of overhaul. A case study was conducted to estimate the availability of the system based on the field data of the seawater desalination plant in Korea and Saudi Arabia. The result was close to the expected availability of the plant.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.04a
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• pp.125-128
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• 2007

The problem of water leakage due to damaging waterproof in concrete structure, causes the impediment in a long term and shortened the life span of durability. There are a lot of techniques for repair and reinforcement to improve using environment. However, the improper construction which is unconsidered various environmental conditions, could effect to increase the maintenance expenses. Therefore, this study will be compared and estimated the adhesion liquid and sheet integrate waterproofing material, as analyzing the existing problem. For those result, we would like to arrange the alterative plan for the long durability and user needs of concrete structure.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.1
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• pp.48-54
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• 2023

Guided missiles are a one-shot system that finishes their purpose after being used once, and due to the long-term storage until launch, the storage reliability is calculated during development, and performance is maintained through periodic inspections until the life cycle arrives. However, the reliability standards applied in the development of guided missiles were established by analyzing data accumulated by the United States during long-term operation in the country, and since they are different from our environment, the 00 guided missiles that have been deployed in the armed forces for more than 10 years under the premise that there is a difference from actual reliability. As a result of verifying the appropriateness of the current inspection cycle by analyzing the actual reliability of the missile, the necessity of changing the inspection period was derived because it was higher than the predicted reliability. It is proposed to build and utilize a lifespan management system that can systematically collect all data such as shooting and maintenance results by classification, and to establish a reliable reliability standard based on the accumulated data.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.42-45
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• 2002

Building remodeling concept includes maintenance & repair and renovation. We have long-term repair plan and special repair fund system for the apartment maintenance & repair, but they do not operate well. And laws and ordinances are being revised in relation with renovation. However, more policy improvement and assistance are needed in order to activate the apartment remodeling project. Especially preferential loan and tax reduction policy and deregulation of building provisions are the main tasks for the apartment remodeling.

• Journal of the Korean housing association
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• v.16 no.5
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• pp.67-74
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• 2005

The performance of building should be deteriorated with time while the building would maintain and manage the function and performance to get a living condition. For the efficient maintenance of the building, the repair cycle would be provided and applied during the service-life time. The service-life time of the building components would be needed to determine the repair time and the repair scope. The service-life time of the building components would be calculated with the 1st repair time and the recovery rate of the performance, considering the recovery rate after repaired. In this paper, the 1st repair time would be estimated with the normal probability distribution, choice probability and 3rd quadratic function. The recovery rate of the building components assumes various level according to the research target and utility area. The results of this study are as follows ; first, most of the components of the building work would range about 30 years in the service-life time and the components of the mechanical works range from 28 years to 37 years, those of the electrical works would be about 31 years.

• Korean Journal of Construction Engineering and Management
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• v.20 no.6
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• pp.34-43
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• 2019

The maintenance cost for road pavement is gradually increasing due to the continuous increase in road extension as well as increase in the number of old routes that have passed the public period. As a result, there is a need for a method of minimizing costs through preventative grievance preventive maintenance requires the establishment of a strategic plan through accurate prediction of road pavement. Hence, In this study, the deep neural network(DNN) and the recurrent neural network(RNN) were used in order to develop the expressway pavement damage prediction model. A superior model among these two network models was then suggested by comparing and analyzing their performance. In order to solve the RNN's vanishing gradient problem, the LSTM (Long short-term memory) circuits which are a more complicated form of the RNN structure were used. The learning result showed that the RMSE value of the RNN-LSTM model was 0.102 which was lower than the RMSE value of the DNN model, indicating that the performance of the RNN-LSTM model was superior. In addition, high accuracy of the RNN-LSTM model was verified through the comparison between the estimated average road pavement condition and the actually measured road pavement condition of the target section over time.

• Journal of Korean Society for Quality Management
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• v.49 no.4
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• pp.581-594
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• 2021

Purpose: The purpose of this study is to compare machine learning models for anomaly detection of mechanical facility equipment and suggest an anomaly detection system for mechanical facility equipment in subway stations. It helps to predict failures and plan the maintenance of facility. Ultimately it aims to improve the quality of facility equipment. Methods: The data collected from Daejeon Metropolitan Rapid Transit Corporation was used in this experiment. The experiment was performed using Python, Scikit-learn, tensorflow 2.0 for preprocessing and machine learning. Also it was conducted in two failure states of the equipment. We compared and analyzed five unsupervised machine learning models focused on model Long Short-Term Memory Variational Autoencoder(LSTM-VAE). Results: In both experiments, change in vibration and current data was observed when there is a defect. When the rotating body failure was happened, the magnitude of vibration has increased but current has decreased. In situation of axis alignment failure, both of vibration and current have increased. In addition, model LSTM-VAE showed superior accuracy than the other four base-line models. Conclusion: According to the results, model LSTM-VAE showed outstanding performance with more than 97% of accuracy in the experiments. Thus, the quality of mechanical facility equipment will be improved if the proposed anomaly detection system is established with this model used.

• Korean Journal of Construction Engineering and Management
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• v.10 no.6
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• pp.67-77
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• 2009

Infrastructure asset management can be defined as the long term and cost effective management strategy to meet the required service level. In most developed countries, the major motivations of the introduction of asset management are increment in number of assets, extension of maintenance field, accounting approaches of public facilities, performance-based FM(Facility Management), limitations of public funds and public-private partnership, life cycle cost approach, and the development of information technology. This paper discusses the strategic and stepwise methods of introducing infrastructure asset management. Strategic approaches are suggested to develop the practical methods of condition and value assessment of assets, and long-term capital investment plan for optimized decision making(ODM). Required systematic processes are analyzed in terms of resource and technical limitations and detailed implementation plan for each development phases are suggested.

• Korean Journal of Construction Engineering and Management
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• v.19 no.1
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• pp.32-42
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• 2018

The importance of facility maintenance management cannot be overemphasized in that not only the value but also the performance of the facility is determined by the level of maintenance. The maintenance cost of the facility ranges from 3 to 10 times the initial construction cost depending the type and use of the facility over the life span. This maintenance importance is increased for the group of facilities and even more critical when the facilities compete for the limited budget with the limited resources such as manpower and equipment. This study analyzed sixteen public facility management corporations primarily for three items: 1) facility management system, 2) long-term rehabilitation plan, 3) the rehabilitation selection system. This paper provides and recommends the key elements of the facility maintenance management system based on the analysis of the sixteen corporations.