• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.100-107
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• 2024

Currently, in Korea, due to the rapid aging and deterioration of facilities, the minimum Maintenance Level and Performance Level' of facilities are required by the 'Facility Safety Act' or 'Infrastructure Management Act'. Since infrastructure assets have a long lifespan and the pattern of deterioration over time is complex, it is very difficult to maintain infrastructure as 'minimum maintenance state' or 'minimum performance state' by the current way of management. 'Asset Management' shall be performed not only by a technical perspective, but also by an accounting perspective such as cost and asset value. However, due to lack of awareness of 'asset management' among stakeholder, only technical perspective management is being carried out in practice. In order to effectively manage infrastructure assets, complex consideration of various asset value factors such as budget and service as well as safety and durability are required. In this paper, we presented a theory to evaluate and quantify the road network value for efficient asset management of the road network. We also presented a method of simulation to apply the theory presented in this paper. Through simulation and the results derived from this study, it is possible to specify the budget for the future national asset management, and to optimize the strategy for the management of old road facilities.

• Corrosion Science and Technology
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• v.14 no.2
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• pp.47-53
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• 2015

Recently, the bending process is greatly applied to fabricate the pipe line. Bending process can reduce welding joints and then decrease the number of inspection. Thus, the maintenance cost will be reduced. Induction heat bending process is composed of bending deformation by repeated local heat and cooling. By this thermal process, corrosion properties and microstructure can be affected. This work focused on the effect of induction heating bending process on the properties of ASME SA106 Gr. C low carbon steel pipes. Microstructure analysis, hardness measurements, and immersion corrosion test were performed for base metal and bended area including extrados, intrados, crown up, and down parts. Microstructure was analyzed using an optical microscope and SEM. Hardness was measured using a Rockwell B scale. Induction heat bending process has influenced upon the size and distribution of ferrite and pearlite phases which were transformed into finer structure than those of base metal. Even though the fine microstructure, every bent area showed a little lower hardness than that of base metal. It is considered that softening by the bending process may be arisen. Except of I2, intrados area, the others showed a similar corrosion rate to that of base metal. But even relatively high rate of intrados area was very low and acceptable. Therefore, it is judged that induction heat bending process didn't affect boric acid corrosion behaviour of carbon steel.

• Plant Journal
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• v.11 no.2
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• pp.39-44
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• 2015

According to a research that is based on a previous study, But in a different way, This study shows fault diagnosis of Induction motor bearing which runs in coal-fired power plant industries on Desulfurization absorber agitator using Spectrum analysis of Stator Current and visual inspection. As a result of harmonic content analysis of stator current spectrum, It was possible to detect ball and outer race fault frequency. The comparison in the context of this experiment proves that the amplitude of faulty frequency is increased in three times at a fault in ball and in outer race. Spectrum analysis of stator current can be used to detect the presence of a fault condition as well as experiment in faulty bearings, besides early fault detection in bearings can prevent unexpected power generation loss and emergency maintenance cost.

• Journal of the Korea Society of Computer and Information
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• v.25 no.10
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• pp.15-22
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• 2020

In this study, we propose an improvement method that can create U-Net model which detect fine concrete cracks by applying a weighted loss function. Because cracks in concrete are a factor that threatens safety, it is important to periodically check the condition and take prompt initial measures. However, currently, the visual inspection is mainly used in which the inspector directly inspects and evaluates with naked eyes. This has limitations not only in terms of accuracy, but also in terms of cost, time and safety. Accordingly, technologies using deep learning is being researched so that minute cracks generated in concrete structures can be detected quickly and accurately. As a result of attempting crack detection using U-Net in this study, it was confirmed that it could not detect minute cracks. Accordingly, as a result of verifying the performance of the model trained by applying the suggested weighted loss function, a highly reliable value (Accuracy) of 99% or higher and a harmonic average (F1_Score) of 89% to 92% was derived. The performance of the learning improvement plan was verified through the results of accurately and clearly detecting cracks.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.3
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• pp.1-10
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• 2011

This program was developed to operate and manage the massive digital forest cover type map using SDE(spatial database engine) in order to solve the problems of the analogue mapping system, mapping process and managing vast amounts of data. It was established the standardization process by performing the several functions of application related to the spatial DB search, mapping history and progress control, modification and inspection of the topology error, approval and reject of those maps. It can be possible to generate the effective mapping and distribute maps to the public service. It is expected that the results will be able to reduce time-cost.

• Journal of the Korean housing association
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• v.23 no.3
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• pp.1-11
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• 2012

The purpose of this study was to make clear considerations in the planning of community housing and the roles of coordinators. Seongmisan village, a representative urban community village in Seoul, was selected for this study on problem solving between residents and opinion coordination between residents and coordinators. For this qualitative research, 2 residents and 2 coordinators answered 'open questionnaires' on prior basic planning, land purchase, financing, architectural planning, construction and inspection, and actual living conditions thereafter. They were each interviewed for 2 hours at a time that was 14-16 months after the residents started living in the new houses, and the records were transcribed. The following was the result. 1) The residents, who ruled the steps of prior basic planning and land purchase, did not have sufficient information or knowledge of the construction of community housing, so that they faced difficulties especially in the legal and financial aspects. 2) The coordinators participated in the project at the steps of architectural planning and construction. The residents accepted the coordinators' opinions on the choice of floor and position, and the coordinators listened to the residents' opinions on individual plans and finishing materials. In the construction step, however, there was conflict between them, and dissatisfaction occurred on the completion time and construction cost. For the successful construction of community housing, a professional coordination company needs to join the project to establish a system of opinion coordinating from the step of prior basic planning to the step of afterconstruction management.

• Korean Journal of Construction Engineering and Management
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• v.2 no.2 s.6
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• pp.37-46
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• 2001

Business boundaries of firms in the construction industry are strictly regulated in Korea. Under the current law, firms involved in construction processes are classified into five categories; general contractors, specialty contractors, architects' offices, engineering firms, and specialized in inspection. Among these types of firms, general contractors are prohibited to enter into specialty contractor's market and vice versa by the basic law in the construction industry. Also general contractors are not allowed to provide architectural services. The purpose of the law is to prohibit unlicensed companies from entering the construction market and to protect customers. However, the law causes critical problems e.g. low efficiency of production and rent creation. Therefore, we identify problems concerning business boundaries of firms in the construction industry and predict structural changes in the them when they are liberalized. So we surveyed general contractors and specialty contractors in Korea to estimate the effects of the liberalization on the construction industry. Most of contractors point to the enhancement of production efficiency as the motivation to integrate other construction process. If current regulations, which limit firms' decisions on business boundaries, are eliminated, firms will choose optimal business scopes taking into account types of contracts adopted by the Government for public works. Based on the cost/benifit analyses, they will decide whether to intergrate other production processes or not.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.261-271
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• 2014

Construction industry becomes large and complicated as that occurred in the construction processes and operations, and the growing social demand for more systematic and efficient methods of integrated management increases. Current facility maintenance system has been regarded as large labor-intensive and fairly stagnant, and faced on several issues including inefficiency in cost and time to collect and utilize various field information. Thus, this paper presents a maintenance prototype utilizing NFC technology and smart devices to efficiently collect and manage the field information in the course of the construction processes. By choosing dam facilities as a case study, construction data for dam inspection and maintenance were classified according to dam maintenance guideline, and database structure was constructed to incorporate with the NFC tags and smart device interface. The system prototype presented in this paper would improve the quality of the dam facilities maintenance system and provide business convenience and usability by contributing increased efficiency of field information management and sharing.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.1
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• pp.73-76
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• 2010

The issue of inspection and characterization of microstructures has emerged as a major consideration in design, fabrication, and detection of MEMS devices. However, the conventional measurement techniques, including scanning electron microscopy (SEM) imaging, atomic force microscopy (AFM) scanning, and mechanical surface profiler, require often destructive process or may be difficult to measure with a wafer scale. In this paper, we characterize the surface profiles of microstructures using an optical scanner based on a DVD pick-up module. Scanning images of the microstructures are successfully generated using the intensity of reflected light from different depths of the surface profiles, based on the focus error signal (FES) from photodiodes. It is shown that the proposed optical scanner can be used as an alternative measurement system with high performance and low cost, compared to conventional measurement techniques.

• Journal of Korean society of Dental Hygiene
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• v.7 no.2
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• pp.123-133
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• 2007

This document is about immigrant worker who use counseling office for human rights in the Daegu Gumin Church. We researched their oral health state so that we can understand their situation and support them properly. General characteristics of study subjects, habits related to oral health, the oral examination and treatment clinic, participated in oral heath education program were studied by designed administered questionaire. And decay, filling(treatment teeth), missing tooth(lost teeth by dental-caries)was counted by oral examination, and calculated DMFT-index. This study was done from the July, 9, 2006 to Aug. 8, 2006. In a total of 289 immigrant worker, 77.9% of them were men and 22.1% of them were women. 55.7% of their salary was from 1,000,000 won to 1,500,000 won and most of them were working for a fiber industry. Many of them are living in korea for more then three years. DMFT index for men was 2.77 and for women was 4.06 so average of DMFT index was 3.06. 46.7% of them said that they are healthy in oral health state. The question for having difficulty using dental clinic in korea, 65.1% of them said "it is difficult". First reason was a communication problem and second was time. Most of them didn't have a oral health education but 85.1% of them said that they are looking forward to attending oral health education. Immigrant worker had better DMFT index then that of korean blue color worker. But still it is quite difficult for them using dental clinic in korea also cost. It is necessary to support them properly that medical insurance system, medical facilities of quality, medical insurance subscriber beside, made by their language, manual for them. At once, medical service improvement a policy is necessary for immigrant worker in korea.