• Corrosion Science and Technology
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• v.6 no.5
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• pp.233-238
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• 2007

Due to the occasional occurrence of a localizedcorrosion such as a SCC and pitting in steam generator tubing(Alloy 600), leading to a significant economical loss, an effective repair technology is needed. For a successful electrodeposition inside a tube, many processes should be developed. Among these processes, an anode to be installed inside a tube, a degreasing condition to remove any dirt and grease, an activation condition for a surface oxide elimination, a strike layer forming condition which needs to be adhered tightly between an electroforming layer and a parent tube and a condition for an electroforming layer should be established. Through a combination of these various process condition parameters, the desired material properties can be acquired. Among these process parameters, various material properties including a mechanical property and its variation along with the height of the electrodeposit inside a tube as well as its thermal stability and SCC resistance should be assessed for an application in a plant. This work deals with the material properties of the Ni electrodeposits formed inside a tube by using the anode developed in this study such as the current efficiency, hardness, tensile property, thermal stability and SCC behavior of the electrodeposit in a 40wt% NaOH solution at $315^{\circ}C$. It was found that a variation of the material properties within the entire length of the electrodeposit was quite acceptable and the Ni electrodeposit showed an excellent SCC resistance.

• Korean Journal of Construction Engineering and Management
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• v.12 no.2
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• pp.101-110
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• 2011

Because bridges can cause more significant damage than other infrastructure a certain level of safety shall necessarily be secured for users. As most of bridges' service life become 20-30 years there will be a dramatic increase in the maintenance and repair cost but the budget and human resource will be limited. Asset management technique can help the efficiency in maintenance and budget management with the limited resource. For its application, there must be a way to evaluate how bridges provide service to users. The level of service can be quantified by a performance measure. This study introduces performance measures and an evaluation process for the determination of level of service. The evaluation results will be used as a fundamental information in the determination of maintenance/repair/management targets and in the decision making process of the bridge asset management.

• Journal of the Korea Institute of Building Construction
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• v.23 no.1
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• pp.57-68
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• 2023

To maintain the normal function of an aging building, regular inspection, repair, and reinforcement must be performed. However, the form of information and decision-making generated in the current building maintenance stage still depends on inefficient methods. This causes an increase in cost and waste of time in building maintenance. Therefore, this study proposed a COBie-IM document for building inspection and maintenance information management by benchmarking COBie, and suggested a method of checking information by linking it with BIM. In addition, a method for visualizing the designation of colors according to the damage grade of defects occurring in the building was suggested. Through this, we are able to systematically integrate and manage the information generated during inspection and maintenance in the building maintenance stage. This is expected to increase work efficiency by supporting decision-making that determines the priority of repair and reinforcement for defects.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.73-80
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• 2009

To repair the deteriorated concrete structures, the deteriorated parts should be removed by using surface treatment methods and replaced by new construction materials. Hydrodemolition is one of the most effective methods for chipping off the deteriorated concrete and treating the remaining concrete. The water jet can remove the deteriorated concrete without damaging the reinforcement steel and surrounding aggregates. Using the water jet system improves surface texture, which ensures to improve adhesive strength between new and old concretes. In this study, three different concrete slab strengths and two water jet machine sets were investigated. Experimental results showed the relationship between concrete strength and water jet condition and this would enable to provide the information of the domestic water jet system and specification, which would contribute to automatization and efficiency of concrete repairing and rehabilitation works.

• Journal of the Korea Institute of Building Construction
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• v.24 no.3
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• pp.355-362
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• 2024

The sustained upkeep of apartment buildings necessitates ongoing maintenance and timely repairs, particularly given their complex nature due to extensive areas, common facilities, and multiple residential and service structures. Additionally, the need for cost-effective maintenance is paramount for ensuring safety, preserving value, and maintaining economic efficiency. However, the multitude of external variables influencing apartment complex maintenance, coupled with the challenges in data collection, have resulted in limited research in this domain. To address this gap, the current study aims to develop a framework for predicting maintenance costs utilizing deep learning techniques, grounded in real-world apartment complex maintenance cost data. This study intends to provide a practical and valuable contribution to the field of apartment complex management, empowering stakeholders with enhanced predictive capabilities for optimizing maintenance strategies and resource allocation.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.459-465
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• 2007

This study was conducted to calculate the LCC of a apartment complex with a type of heating system, district heating and cogeneration system. For the purpose of analyzing LCC according to size of apartment complex, 500, 1,500 and 4,000 houses of model apartment selected. This research performs design of heating system and the life cycle cost analysis including an initial cost, energy cost, maintenance and operation cost, replacement cost and renovation cost during the project period(15years). According to the calculated results, 1) Initial cost of cogeneration system with 500, 1500 and 4000 houses is higher than district heating system each of 20%, 13%, 12%. 2) In case of cogeneration system, the payback period by electric generation is 5.21, 4.92 and 4.47 years and saving cost was calculated 29 billion won, 94 billion won and 262 billion won after payback period. 3) Cogeneration system LCC was 1.12, 1.07 and 1.06 times larger than district system with the size of apartment complex. According to the case of this study district heating system is more efficient than cogeneration system in terms of the reduction of LCC. 4) Gas Engine Co-generation System is more efficient than other systems because it can collect progressive part from electric charge progressive stage system. However, the efficiency is decreasing because of raising of fuel bills(LNG) and lowering of power rate for house use. Especially the engine is foreign-made so the cost of maintenance and repair is high and the technical expert is short. 5) District heating is also affected by fuel bills so we should improve energy efficiency through recovering of waste heat(incineration heat, etc.). Also, we should supply district cooling on the pattern of heat using of let the temperature high in winter and low in summer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.759-767
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• 2021

Most weapons systems that are Force Integration are expensive equipment that reflects the latest technology, and the operation and maintenance cost is increasing continuously. Factors that efficiently operate and maintain these weapon systems include maintenance plans, economic costs, and repair part requirements. Among them, predicting the repair parts requirements during the life cycle in advance is an important way to increase operation and maintenance cost efficiency and operating availability. The start of requirement analysis for repair parts is a calculation of the CSP (CSP: Concurrent Spare parts, CSP hereafter) that is distributed when the weapon system is deployed. The CSP is an essential component of achieving the operating availability during this period because the weapon system aims to successfully perform a given operation mission without resupply for an initial set period. In the present study, the CSP calculation method was analyzed, reflecting the failure rate and operating time of items, but the analyzed CSP was aimed at preparing for technical failure, but in the initial operating environment, it is limited in coping with unexpected failures caused by human error. The failure is not included in the scope of free maintenance and is a serious factor in making the weapon system inoperable during the initial operation period. To prevent the inoperable status of a weapon system, CSP that considers human error is required in the initial operating environment, and the calculation criteria and measures are proposed.

• Industry Promotion Research
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• v.8 no.4
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• pp.37-46
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• 2023

Due to the aging, advancement, and complexity of chemical facilities, non-routine work such as facility inspection, repair, or maintenance work is increasing. Of the 1,483 accidents that occurred over the past 10 years at chemical product manufacturing sites subject to PSM, accidents that occurred during non-routine work accounted for 56% (932 Cases) of the total. It can be seen that more accidents occur during non-routine work than during routine work. In particular, in order to improve the economy and efficiency of factory operation, there are cases where some facilities are stopped without stopping the entire factory and then inspection, repair, or maintenance work is performed while isolated from the operating facilities. Therefore, first, a safe isolation method must be selected by establishing an isolation standard (Baseline Isolation Standard) based on the chemicals handled, operating conditions, and risk level of the equipment in the chemical plant. Second, since current domestic laws and standards do not suggest the need for specific quarantine standards, it is necessary to institutionalize the preparation of quarantine standards. Technical and institutional improvements are needed to prevent fires, explosions, and poisoning accidents caused by leaks of chemical substances.

• Journal of the Korean Solar Energy Society
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• v.34 no.2
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• pp.32-43
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• 2014

This study set out to identify the importance of each factor influencing facility selection with a survey among public medical facilities under the category of public buildings and apply the importance of economy, technology and environment with the weighting factor method, thus proposing optimal application plans. The research content of each section can be summarized as follows:1) Estimated energy consumption according to the energy simulation was 65,129MWh/yr, which was 18.7% higher than that according to the calculation equation. Of the energy consumption, more than 80% was used by heating and cooling facilities and construction facilities, and 20% was used by electronics such as medical equipments and in and outdoor lighting. 2) The results of a survey on the factors influencing the importance when selecting a new and renewable energy system reveal that the upper items had a priority in economy, environment, and technology in the descending order and that the lower item shad a priority in initial investments, maintenance and repair costs=energy costs, supply reliability, energy efficiency and $CO_2$ emissions in the descending order. 3) The application alternatives were analyzed in economy, technology, and environment. As a result, a geothermal system turned out to be the most excellent one a cross all the upper and lower comparison items. Of the other systems, a solar thermal system was superior in initial investments, maintenance and repair costs, and energy efficiency, where as a photovoltaic system was superior in energy costs, supply reliability, and $CO_2$ emissions. 4) As for the mixed application ratio among economy, technology, and environment, when the percentage of a geothermal system was approximately 80% or higher in anew and renewable energy system, it was the best and most optimal application plan.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.109-118
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• 2012

Large number of part design for aircraft and automobile is preceded by functional or sectional design groups for efficiency. However, interferences and gaps can be found when the parts and sub-assemblies by those design groups are to be assembled. These interferences and gaps cause design changes and additional repair processes. While interference problem has been resolved by digital mockup and concurrent engineering methodology, gap problem has been covered by temporary treatment of filling gap with sealant. This kind of fast fix causes fatal problem of leakage when the gap is too big for filling or the treatment gets old. With this research, we have developed a program to find the gap automatically among parts of assembly so that users can find them to correct their design before manufacturing stage. By using decomposition model representation method, the developed program can search the gap among complex car body parts to be visualized with volumetric information. It can also define the boundary between the gap and exterior empty space automatically. Though we have proved the efficiency of the developed program by applying to automobile assembly, application of the program is not limited to car body only, but also can be extended to aircraft and ship design of large number of parts.