• Journal of the Korean housing association
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• v.26 no.2
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• pp.67-79
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• 2015

As the Korean construction market in the apartment housing has changed to a housing consumer focused market, interest and importance on efficient use and management on existing buildings has increased rather than demand for new buildings. Interest of housing consumers on apartment house quality has increased in this market paradigm, and this spontaneously is connected to quality flaw related defect disputes and lawsuits that the importance of defect diagnosis has continuously increased. This defect diagnosis is directly connected to maintenance charges in defect dispute and lawsuit processes that rather objective and highly credible progress of duty is required. However, most defect diagnosis firms today that progress defect diagnosis are using different diagnosis methods and depend on the experience of experienced professionals that there is no standardized defect diagnosis process. Therefore, the purpose of this study is to provide common defect diagnosis process model for defect diagnosis firms utilizing the BPMN (Business Process Modeling Notation) modeling method. It is expected that this will contribute to professional and reliable task performances of concerned defect diagnosis workers. Furthermore, it is expected that design lawsuit damage will be substantially reduced by standardizing defect diagnosis processes.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.5
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• pp.343-350
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• 2016

Remaining lifetime prediction of the underground gas pipeline plays a key role in maintenance planning and public safety. One of main causes in the pipeline failure is metal corrosion. This paper deals with estimating the pipeline reliability in the presence of corrosion defects. Because a pipeline has uncertainty and variability in its operation, probabilistic approximation approaches such as first order second moment (FOSM), first order reliability method (FORM), second order reliability method (SORM), and Monte Carlo simulation (MCS) are widely employed for pipeline reliability predictions. This paper presents a fuzzy inference based reliability method (FIRM). Compared with existing methods, a distinction of our method is to incorporate a fuzzy inference into quantifying degrees of variability in corrosion defects. As metal corrosion depends on the service environment, this feature makes it easier to obtain practical predictions. Numerical experiments are conducted by using a field dataset. The result indicates that the proposed method works well and, in particular, it provides more advisory estimations of the remaining lifetime of the gas pipeline.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_2
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• pp.669-678
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• 2023

Recently, spatial information has been applied to various fields and its usability is increasing day by day. In particular, in the field of civil engineering and construction, BIM based on spatial information is being applied to all construction industries and related research has been conducted. BIM is a technology that utilizes spatial information from the design phase and aids in the construction and maintenance of buildings, including the management of their attributes. However, to apply BIM technology to existing buildings, it takes a lot of time and money to produce models based on design drawings along with current surveying. In this study, quantitative and qualitative analysis was conducted to determine the applicability of the acquired data and the applicability of BIM by generating data and analyzing the accuracy using UAV images and ground lidar, which are representative spatial information acquisition methods. Quantitative analysis revealed that TLS (Terrestrial Laser Scanner) showed reliable accuracy in both planar and elevation measurements, whereas unmanned aerial images exhibited lower accuracy in elevation measurements, resulting in reduced reliability. Qualitative analysis indicated that neither TLS nor unmanned aerial images alone provided perfect completeness. However, the combination of both spatial information sources, tailored to specific needs, resulted in the most comprehensive completeness. Therefore, it is concluded that the appropriate utilization of spatial information acquired through unmanned aerial images and TLS holds the potential for application in the fields of BIM and reverse engineering.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.191-198
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• 2001

Present status of railroad slopes through the field investigation in 26 selected slopes and/or rockfall at risk was grasped. From the evaluation of field data, main characteristics of railroad slopes are that 1) the possibility of failure by rockfall is high, 2) the Possibility of failure by slope itself is low and 3) rockfall's risk at the in and out part of tunnel is especially high. To maintain the railroad slopes systematically and reasonably, it is necessary to make and to use the database of slopes information along the railroad. Furthermore, through the construction of basic slopes' information, maintenance system of railroad slopes was developed in connection with IR-DiPS(Intelligent Railroad - Disaster Prevention System) in the future.

• Journal of Wind Energy
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• v.9 no.4
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• pp.5-8
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• 2018

Optimum performance and reliable operation of wind turbines and/or wind farms are crucial parameters for stakeholders such as OEMs, operators, owners and investors. The efficiency and life time of wind power heavily depends on operation and maintenance efforts. Every manufacturer or owner wants to have wind turbines with high reliability, which can be defined as the probability that a wind turbine will perform its designed function for a certain period of time under stated conditions. In this regard, IEC WG26 is now developing a technical specification defining information categories from which reliability metrics can be identified and reported.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.2
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• pp.16-26
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• 2020

Improving operator performance in complex and time-critical situations is critical to maintain plant safety and operability. These situations require quick detection, diagnosis, and mitigation actions to recover from the root cause of failure. One of the key challenges for operators in nuclear power plants is information management and following the control procedures and instructions. Nowadays Digital Twin technology can be used for analyzing and fast detection of failures and transient situations with the recommender system to provide the operator or maintenance engineer with recommended action to be carried out. Systems engineering approach (SE) is used in developing a digital twin for the CEDM system to support operator actions when there is a misalignment in the control element assembly group. Systems engineering is introduced for identifying the requirements, operational concept, and associated verification and validation steps required in the development process. The system developed by using a machine learning algorithm with a text mining technique to extract the required actions from limiting conditions for operations (LCO) or procedures that represent certain tasks.

• Agribusiness and Information Management
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• v.9 no.2
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• pp.22-26
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• 2017

This study aims to understand why public information systems in agricultural fields have shown lower performances than other industrialized fields and industries and how these problems would be fixed and overcame. To accomplish this research purpose, this study would overview the previous studies on developing agricultural information systems in public sectors and would find out meaningful and considerable factors. This study would accept the methodologies of literature review and systems thinking approaches to understand the relationships among the found factors and to suggest the conceptual research model. Agricultural information system should take care to reduce implement and maintenance costs to reduce the negative relationships between costs and expected service value and between expected service value to perceived service value. Also, it should be understood that impersonal response would reduce the eager to use the services, so the government sectors should consider positively to adopt the concept of CRM even though the government sectors traditionally have ignored its necessity. The failure of public information systems/services may be caused not only by lack of the contents but also by the failure of the persistent post management.

• KIEAE Journal
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• v.14 no.4
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• pp.19-26
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• 2014

The building section is providing immediate causes for global climate change problems since it takes about 50% of carbon emission, 20~50% of waste discharge, 33% of energy consumption, 40% of resource use, and 17% of water consumption. So, many countries over the world have developed and implemented green building certification systems to assess sustainable performances of buildings since the early 1990s. In korea, the green building certification system to induce the diffusion of sustainable buildings was first introduced in 2002 and developed as an improved version of the G-SEED(Green Standard for Energy and Environmental Design) system in 2013 after major revisions of related legislations. This research conducts a survey targeting residents on an apartment building that was certified as green building and examines the importance of assessment criteria on apartment buildings to certify green buildings using the Analytic Hierarchy Process(AHP) method. And it proposes a new direction on certification assessment standards from the resident's prospective. As a result, assessment criteria such as indoor environment, ecological environment, energy & environment pollution, and maintenance management among 7 main ones turned out important on assessing the G-SEED system for apartment buildings, while criteria such as material & resource, water circulation management, and land use & transportation did relatively unimportant.

• Journal of Energy Engineering
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• v.26 no.2
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• pp.1-11
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• 2017

While they are becoming more viable, synthetic natural gas (SNG) plants, with their high temperatures and pressures, are still heavily dependent on advancements in the state-of-the-art technologies. However, most of the current work in the literature is focused on optimizing chemical processes and process variables, with little work being done on relevant mechanical damage and maintenance engineering. In this study, a combination of pipe system stress analysis and detailed local stress analysis was implemented to prioritize the inspection locations for main pipes of SNG plant in accordance to ASME B31.3. A pipe system stress analysis was conducted for pre-selecting critical locations by considering design condition and actual operating conditions such as heat-up and cool-down. Identified critical locations were further analyzed using a finite element method to locate specific high-stress points. Resultant stress values met ASME B31.3 code standards for the gasification reactor and lower transition piece (bend Y in Fig.1); however, it is recommended that the vertical displacement of bend Y be restricted more. The results presented here provide valuable information for future risk based maintenance inspection and further safe operation considerations.

• Journal of Wetlands Research
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• v.19 no.1
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• pp.45-51
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• 2017

Nepal is a landlocked mountainous country in South Asia, located between China to the north and India to the south, east, and west. As such, wastewater management has become one of the most significant problems in urban area of Nepal. In Nepal, the centralized wastewater treatment systems were dysfunctional due to high cost of operation, discontinuous power supply, lack of proper maintenance and proper technical workforce to address the issues. As such, constructed wetlands (CW) were applied to treat various secondary wastewater as alternative to wastewater treatment facilities. Generally, efficiency and sustainability of CW technology depends on proper operation and maintenance and active community involvement. This study summarizes information about 26 CW in Nepal. Specifically, factors including data banking, removal efficiency, quality of discharged water, compliance to water quality standard of Nepal and operation and maintenance were investigated. Considering removal efficiency per pollutant, Ka-1 achieved the greatest reduction for most pollutant followed by B-1, L-3, Ka-5 and K-1. Nepal has practiced CW technology for more than 2 decades but currently, development of technology was interrupted by the inefficient performance of existing facilities. Public awareness about the technology, natural disaster, unavailability of specified substrate materials, lack of fund for further research and experiments has hindered the expansion of technology. In spite of these concerns, CW was still proven as an alternative solution to the present wastewater problems in urban areas of Nepal.