• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.3 s.55
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• pp.181-187
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• 2009

This paper is to investigate about a new technique (Bow system) which is to develop the disadvantages of the external post-tensioned method. The purpose of this paper is to analyze about the prestress loss when the loads apply along the long term and to improve the capacity of the members strengthened by Bow system. The variables in the test program are the span/depth ratio, the amount of tendon area. And the test was carried out to confirm the long term behaviour. It is shown that can apply the current code in the design, and have no the structural problems about the prestress loss.

• International Journal of Highway Engineering
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• v.19 no.5
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• pp.1-11
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• 2017

PURPOSES : This study is aimed at development of a stochastic pavement deterioration forecasting model using National Highway Pavement Condition Index (NHPCI) to support infrastructure asset management. Using this model, the deterioration process regarding life expectancy, deterioration speed change, and reliability were estimated. METHODS : Eight years of Long-Term Pavement Performance (LTPP) data fused with traffic loads (Equivalent Single Axle Loads; ESAL) and structural capacity (Structural Number of Pavement; SNP) were used for the deterioration modeling. As an ideal stochastic model for asset management, Bayesian Markov multi-state exponential hazard model was introduced. RESULTS:The interval of NHPCI was empirically distributed from 8 to 2, and the estimation functions of individual condition indices (crack, rutting, and IRI) in conjunction with the NHPCI index were suggested. The derived deterioration curve shows that life expectancies for the preventive maintenance level was 8.34 years. The general life expectancy was 12.77 years and located in the statistical interval of 11.10-15.58 years at a 95.5% reliability level. CONCLUSIONS : This study originates and contributes to suggesting a simple way to develop a pavement deterioration model using the total condition index that considers road user satisfaction. A definition for level of service system and the corresponding life expectancies are useful for building long-term maintenance plan, especially in Life Cycle Cost Analysis (LCCA) work.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.1
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• pp.279-288
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• 2003

This study is the development of method on repairing concrete structure for progressing the durability of reinforced concrete. This method is wet spray method which compress and conduct mortar pre-mixed with polymer powder to hose by high pressure pump and spray it on the section of concrete structure through nozzle made specially. Characters of this method are that materials are selected with the sort of structure and the cause of deterioration and macro pores are removed in repaired section by conducting with high pressure and spraying with high velocity for progressing the durability of concrete structure. This study has carried out that the minimum capacity of rebound was measured with various condition and physical properties of sample made by spray method were estimated in comparing with sample made by previous hand method. Also, properties of long-term have carried out after this method was applied on site. According to experimental study, the capacity of rebound showed below 5% and physical properties of sample made by spray method were superior to that of sample made by hand method and physical and durable properties of long-term showed excellence.

• Journal of the Korean institute of surface engineering
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• v.51 no.5
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• pp.316-324
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• 2018

Harsh seawater environment is subdivided into marine atmosphere, splash zone, tidal zone, submerged zone and bottom of sea depending on the exposed part. Since corrosion rate depends on the conditions of the exposed parts, proper protection and maintenance for each parts are essential for long-term use of steel structures in seawater environment. For steel structures which were installed in Shiwha Lake, a special maintenance system is required to guarantee its long-term durability and safety. As the tidal power plant has recently been operated, the salinity has risen due to the rapid influx of seawater upstream into Sihwa Lake and the corrosion tendency of the structure is variable according to the water level fluctuation. In this study, corrosion properties of steel structures under water level fluctuation was evaluated by corrosion rate measurement, visual inspection and natural potential measurement and their durability and life management were discussed in view of the effect of variation in of seawater level fluctuations in Shihwa Lake.

• Korean Medical Education Review
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• v.25 no.2
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• pp.126-131
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• 2023

The aim of this study was to systematically collect data for evaluating short- and long-term outcomes using Kirkpatrick's four-level evaluation model, Chonnam National Medical School has established plans for developing and managing a database of student and graduate cohorts. The Education Evaluation Committee, with assistance from the Medical Education Office, manages the development and maintenance of cohort data. Data collection began in the 2022 academic year with first- through fourth-year medical students and graduates of the year 2022. The collected data include sociodemographic characteristics, admission information, psychological test results, academic performance data, extracurricular activity data, scholarship records, national medical licensing exam results, and post-graduation career paths. The Education Evaluation Committee and the Medical Education Office analyze the annually updated student and graduate cohort data and report the results to the dean and relevant committees. These results are used for admissions processes, curriculum improvement, and the development of educational programs. Applicants interested in using the student and graduate cohort data to evaluate the curriculum or conduct academic research must undergo review by the Educational Evaluation Committee before being granted access to the data. It is expected that the collected data from student and graduate cohorts will provide a sound and scientific basis for evaluating short- and long-term achievements based on student, school, and other characteristics, thereby supporting medical education policies, innovation, and implementation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.40-48
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• 2017

RC flat plates may be governed by a serviceability as well as a strength condition, and a construction sequence and its impact on the distributions of gravity loads among slabs tied by shores are decisive factors influencing short and long term behaviors of flat plate. Over-loading and tensile cracking in early-aged slabs significantly increase the deflection of a flat plate system under construction, and a reshoring work may be helpful in reducing slab deflections by controlling the vertical distributions of loads in a multi-shored flat plate system. In this study, a effect of reshoring works on short and long term deflections of flat plate systems are analyzed. The slab construction loads with various reshoring schemes and slab design and construction conditions are defined by a simplified method, and the practical calculation of slab deflections with considering construction sequences and concrete cracking and long term effects is applied. From parametric studies, the reshoring works are verified to reduce slab deflections, and the optimized conditions for the reshoring works and slab design and constructions are discussed.

• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.71-78
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• 2023

In general, electric submersible pumps (ESPs), which have an average life of 1.0 to 1.5 years, experience a decrease in performance and a reduction in life of the pump depending on oil and gas reservoir characteristics and operating conditions in wells. As the result, the failure of ESP causes high well workover costs due to retrieval and installation, and additional costs due to shut down. In this study, a flow loop system was designed and established to predict the life of ESP in long­term operation of oil and gas wells, and the life cycle data of ESP from the time of installation to the time of failure was acquired and analyzed. Among the data acquired from the system, flow rate, inlet and outlet temperature and pressure, and the data of the vibrator installed on the outside of ESP were analyzed, and then the performance status according to long-term operation was classified into five stages: normal, advice I, advice II, maintenance, and failed. Through the experiments, it was found that there was a difference in the data trend by stage during the long­term operation of the ESP, and then the condition of the ESP was diagnosed and the failure of the pump was predicted according to the operating time. The results derived from this study can be used to develop a failure prediction program and data analysis algorithm for monitoring the condition of ESPs operated in oil and gas wells.

• Land and Housing Review
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• v.10 no.2
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• pp.1-13
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• 2019

This study suggests that the system improvement priority of the Natural Conservation Zone of the Metropolitan Area Maintenance Planning Law, which was enacted for about 37 years. First of all, through the precedent research and the consultation meeting, the improvement plan was divided into the short term and the mid(or long) term. Important findings and implications are as follows. The short-term priority results were 'Improve water quality regulation', 'Strengthen individual location regulations of factories and induce multi-use plan position', and 'Improvement of waterfront area regulation', which were both critical and urgent. The mid-term(or Long-term) priority results were 'To integrate development and environmental duplication regulations', 'Abolition and unification of environmental laws', and 'Adjustment and resetting of natural conservation areas', which were both critical and urgent. On the other hand, 76.4% of the residents and 64.5% of the experts are concerned about the necessity of improvement of the Natural Conservation Zone system. Both residents and experts seem to be aware of the necessity. Opinions about Improvement and mitigation of regulations on Natural Conservation Zone that were constantly raised. In the past, there was a temporary and fragmented institutional mitigation of the government. However, with the rapid development of eco-friendly technologies since 2010, Our Country Conditions is in a transition period. This study has significant implications for the improvement and mitigation of metropolitan area regulations.

• Journal of Korean Association for Spatial Structures
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• v.21 no.3
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• pp.85-92
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• 2021

The purpose of this paper is to understand the key factors for efficient maintenance of rapidly aging facilities. Therefore, the safety inspection/diagnosis reports accumulated in the unstructured data were collected and preprocessed. Then, the analysis was performed using a text mining analysis method. The derived vulnerabilities of tunnel facilities can be used as elements of inspections that take into account the characteristics of individual facilities during regular inspections and daily inspections in the short term. In addition, if detailed specification information and other inspection results(safety, durability, and ease of use) are used for analysis, it provides a stepping stone for supporting preemptive maintenance decision-making in the long term.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.388-392
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• 2009

Operation of LNG (Liquefied Natural Gas) plants requires an effective maintenance strategy. To this end, the long-term and short-term trend of faults, such as mechanical and electrical troubles, should be identified so as to take proactive approach for ensuring the smooth and productive operation. However, it is not an easy task to predict the fault trend in LNG plants. Many variables and unexpected conditions make it quite difficult for the facility manager to be well prepared for future faulty conditions. This paper presents a model to predict the fault trend in a LNG plant. ARIMA (Auto-Regressive Integrated Moving Average) model is combined with Wavelet Transform to enhance the prediction capability of the proposed model. Test results show the potential of the proposed model for the preventive maintenance strategy.