• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.12
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• pp.181-188
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• 2019

The maintenance of school building is pivotal issue. However, it is difficult to obtain basic analysis data for LCC(Lifecycle Cost) analysis and maintenance planning of school building. Therefore, this study proposed System Dynamics(SD) techniques to make maintenance decisions for school building. The interaction between the major parameters related to the aging of a building, maintenance activities, and cost were expressed in Causal Loop Diagram. Based on this, the formula for the relationship between causal maps was defined and converted to Stock and Flow Diagram. Through the completed SD model the 50-year plan of 214 educational building were tested by considered in account budget, maintainability, and budget allocation opinions. As a result, the integrated SD model demonstrated that it can support strategic decision making by identifying the status class and LCC behavior of school buildings by scenario. According to the scenario analysis, the rehabilitation action of preventive maintenance that primarily repairs the buildings in condition grade C showed the best performance improvement effect relative to the cost. Therefore, if the proposed SD model is expanded to consider the effects of other educational policies, the crucial performance improvement budget can be estimated in the long-term perspective.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.4
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• pp.505-516
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• 2018

In order to establish an efficient bridge maintenance strategy, the future performance of a bridge must be estimated by considering the current performance, which allows more rational way of decision-making in the prediction model with higher accuracy. However, personnel-based existing maintenance may result in enormous maintenance costs since it is difficult for a bridge administrator to estimate the bridge performance exactly at a targeting management level, thereby disrupting a rational decision making for bridge maintenance. Therefore, in this work, we developed a representative performance prediction model for each bridge element considering uncertainty using domestic bridge inspection data, and proposed a bayesian updating method that can apply the developed model to actual maintenance bridge with higher accuracy. Also, the feasibility analysis based on calculation of maintenance cost for monitoring maintenance scenario case is performed to propose advantages of the Bayesian-updating-driven preventive maintenance in terms of the cost efficiency in contrast to the conventional periodic maintenance.

• Journal of the Korean Institute of Educational Facilities
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• v.9 no.3
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• pp.5-12
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• 2002

This study attempts to suggest a standard for maintenance and repair cost per each unit area, by analyzing the causes and cost of various maintenance and repair work in the university facilities. The result of my study on the data of maintenance and repair work for 12 years between 1990 and 2001 in the two campuses of the university that I selected for my case study is the following. (1) The yearly average for maintenance and repair cost in the facilities of the university with 67 old and new buildings for the past 12 years was $W4,422/m^2$. In addition, the repair cost based on the calculation of the degree of decrepitude of the buildings was $W10,291/m^2$. (2) The number of causes of maintenance and repair work increase steadily every year, due to the development of universities and changes in the educational environment. A special case like a university merger also appears, which also demands maintenance and repair work of university facilities. (3) It is important that a budget for interior maintenance is increased or added to an extent, in order to minimize the maintenance and repair cost of the university facilities, and to cope with changing educational environments flexibly. (4) The publication of a white paper that includes the planning of a building, construction process, and changes in design, seems to be required for the sake of users' convenience and efficient maintenance and repair work.

• Journal of the Korea Society for Simulation
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• v.30 no.1
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• pp.65-73
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• 2021

The maintenance of the guided missiles typically requires the efficient management of spare parts and maintenance time. This study analyzed the impact of the maintenance time on operational availability. This study classifies the maintenance team with consideration of the skill level of the Harpoon guided missile maintenance and the goal is to analyze the impact on the operational availability with the skill levels quantitatively. Based on the real maintenance data of Harpoon guided missiles, a simulation model is constructed and analyzed. The analysis of the simulation result shows the trade-off between the maintenance time and operational availability. It is expected that the simulation model can help the maintenance policies of guided missiles.

• Journal of the Korean Society of Safety
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• v.38 no.4
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• pp.1-7
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• 2023

The steel wheels of urban railway vehicles gather a lot of data through regular measurements during maintenance. However, limited research has been carried out utilizing this data, resulting in difficulties predicting the maintenance period. This paper studied a machine learning model suitable for mileage prediction by studying the characteristics of mileage change according to diameter and flange thickness changes. The results of this study indicate that the larger the diameter, the longer the travel distance, and the longest flange thickness is at 30 mm, which gradually shortened at other times. As a result of research on the machine learning prediction model, it was confirmed that the random forest model is the optimal model with a high coefficient of determination and a low root mean square error.

• Journal of Korean Society of Steel Construction
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• v.18 no.1
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• pp.47-51
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• 2006

Measuring the track geometry of a high-speed railway is the most important task in track construction and track maintenance work. Measuring accuracy is particularly sign the formulation of the maintenance plan and in the assessment of the work quality, and because it can set the train speed limit. To determine the track geometry of a high-speed railway, it is important to use KNR's track recording coach (EM-120). According to the result of the spectrum analysis, noise near the 1-m wave band was found on the track recording data. A new filter was thus applied to remove the noise from the track recording data. A similar result can be acquired when this method is used in real track geometry.

• International Journal of Advanced Culture Technology
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• v.12 no.1
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• pp.254-261
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• 2024

Among eco-friendly energy, solar energy is one of the renewable energy sources that is developing in the spotlight in many countries. In line with this, the Korean government and local governments are carrying out projects to provide subsidies for the distribution of household solar power, raising the spread of household solar power and awareness. However, due to the lack of research on consumer perception of household solar power, this study investigated the perception of household solar power from 2015 to 2022 by setting the central word as solar power. As a result, 2016 had the highest number of collections, and when the top 50 words for each year were analyzed, it was confirmed that words related to the installation and maintenance of household solar power dominated. And through CONCOR analysis, a total of four were derived: solar energy recognition, renewable and eco-friendly energy recognition, solar government policies, solar companies, and perceptions of households. Through emotional analysis, it was confirmed that 2021 had the most positive data. As a result, consumer perception of household solar power is positive based on what was mentioned above, but research on how to use negative opinions on waste control and installation and maintenance should be conducted.

• Journal of KIISE:Databases
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• v.33 no.2
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• pp.175-187
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• 2006

The data cube is an aggregation operator that computes group-bys for all possible combination of dimension attributes. %on the number of the dimension attributes is n, a data cube computes $2^n$ group-bys. Each group-by in a data cube is called a cuboid. Data cubes are often precomputed and stored as materialized views in data warehouses. These data cubes need to be updated when source relation change. The incremental maintenance of a data cube is to compute and propagate only its changes. To compute the change of a data cube of $2^n$ cuboids, previous works compute a delta cube that has the same number of cuboids as the original data cube. Thus, as the number of dimension attributes increases, the cost of computing a delta cube increases significantly. Each cuboid in a delta cube is called a delta cuboid. In this paper. we propose an incremental cube maintenance method that can maintain a data cube by using only $_nC_{{\lceil}n/2{\rceil}}$ delta cuboids. As a result, the cost of computing a delta cube is substantially reduced. Through various experiments, we show the performance advantages of our method over previous methods.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.2
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• pp.84-94
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• 2018

In recent years, the diminishing of operation and maintenance cost using advanced maintenance technology is attracting many companies' attention. Especially, the heavy machinery industry regards it as a crucial problem since a failure of heavy machinery requires high cost and long downtime. To improve the current maintenance process, the heavy machinery industry tries to develop a methodology to predict failure in advance and to find its causes using usage data. A better analysis of failure causes requires more data so that various kinds of sensor are attached to machines and abundant amount of product usage data is collected through the sensor network. However, the systemic analysis of the collected product usage data is still in its infant stage. Many previous works have focused on failure occurrence as statistical data for reliability analysis. There have been less works to apply product usage data into root cause analysis of product failure. The product usage data collected while failures occur should be considered failure cause analysis. To do this, this study proposes a methodology to apply product usage data into failure cause analysis. The proposed methodology in this study is composed of several steps to transform product usage into failure causes. Various statistical analysis combined with product usage data such as multinomial logistic regression, T-test, and so on are used for the root cause analysis. The proposed methodology is applied to field data coming from operated locomotive and the analysis result shows its effectiveness.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.503-508
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• 2007

The Equipment Expenses section of the Poom-Saem, that is used for Construction Cost Estimation on public sectors in Korea, has been rarely revised, and so does not reflect changes of construction equipment technology and construction methods, since it was established based on data from Japan and the U.S in the early 1960s. In order to make reasonable estimation of maintenance costs(Interest, Storage, Insurance, Tax), the equipment expenses section of the Poom-Saem and the domestic and overseas documentary records were investigated. Further, 16 construction sites were visited, and 20 Construction Equipment leasing services were surveyed. Based on results from analysing figures related with the estimation of maintenance costs, the maintenance cost is redefined. Then, construction equipment was classified into 6 exclusive construction equipment and general one, and realistic figures of the maintenance cost, which consists of interest, storage, insurance, tax, are suggested respectively. The optimum level of each item which consists of equipment costs was revealed based on the result of the analysis on the figures of equipment costs calculation from the Poom-Saem and the collected data. The research will be the foundation that helps to estimate appropriate construction costs and the ground work of related studies.