• Korean Journal of Construction Engineering and Management
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• v.5 no.1 s.17
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• pp.99-106
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• 2004

Efficiency and efficient management on maintenance/repair/operation (MRO) phase is getting important with advance in technologies and complex functionalities of building and facility, Using software systems as well as advanced hardware systems in MRO area is spreading along with this trend to take advantage of information technology. Information of building and facility for MRO phase is derived from engineering/procurement/construction (EPC) phase. But most current commercial software systems in EPC and MRO are focusing on their own phase, which arise lack of consistency of information from EPC to MRO phase. But, the information system now used at the MRO phase stop flowing the building and the facilities information and then newly create. Moreover, from an asset management point of view, asset particulars such as the structures and equipments are different the value fluctuation. In order to reflect these information rationally, the construction costs are correctly distributed and the initial price of the asset particulars have to be estimated. In this study, develop the information model which can apply the cost information at the EPC phase to the MRO phase.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.86-93
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• 2020

The demand for maintenance in Korea infrastructure facilities constructed since the 1970s has increased significantly compared to the demand for new construction. Moreover, after the Gyeongju and Pohang earthquakes, seismic performance evaluation, repair, and retrofitting projects have been carried out. Therefore, in this study, a specimen was designed following the L-type GFRP Plate Externally Bonded Retrofit method, one among other retrofit methods. The L-type GFRP Plate was bonded to the specimen by epoxy and a washered steel nail. A four-point bending test was performed to confirm the strengthening effect of the Externally Bonded Retrofit method using an L-type GFRP Plate. The strengthening effect of the L-type GFRP plate was proven experimentally, and the behavior of the beam designed following the L-type GFRP Plate Externally Bonded Retrofit method was evaluated according to Korea's "Design Manual & Specification for Strengthening of RC Structures by Advanced Composites System". Furthermore, the effectiveness of the bonding method, a combination of epoxy and washered steel nail, was also checked. The results showed that the design, according to the guidelines mentioned above, predicted the strength of the member well, but the failure mode did not satisfy the design assumption because of unexpected damage to the GFRP plate due to the fixing method, washered steel nail.

• Journal of Korean Society of Steel Construction
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• v.17 no.2 s.75
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• pp.227-241
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• 2005

This paper presents a practical and realistic Life-Cycle Cost (LCC) optimum design methodology for steel bridges considering the long-term effect of environmental stressors such as corrosion and heavy truck traffics on bridge reliability. The LCC functions considered in the LCC optimization consist of initial cost, expected life-cycle maintenance cost, and expected life-cycle rehabilitation costs including repair/replacement costs, loss of contents or fatality and injury losses, road user costs, and indirect socio-economic losses. For the assessment of the life-cycle rehabilitation costs, the annual probability of failure, which depends upon the prior and updated load and resistance histories, should be accounted for. For the purpose, Nowak live load model and a modified corrosion propagation model, which takes into consideration corrosion initiation, corrosion rate, and repainting effect, are adopted in this study. The proposed methodology is applied to the LCC optimum design problem of an actual steel box girder bridge with 3 continuous spans (40m+50m+40m=130m). Various sensitivity analyses are performed to investigate the effects of various design parameters and conditions on the LCC-effectiveness. From the numerical investigation, it has been observed that local corrosion environments and the volume of truck traffic significantly influence the LCC-effective optimum design of steel bridges. Thus, these conditions should be considered as crucial parameters for the optimum LCC-effective design.

• Journal of the Korean association of regional geographers
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• v.17 no.6
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• pp.710-725
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• 2011

The purpose of this study is to analyze both residential conditions and the resident impressions of the transition zone of central Daegu. The results drawn from a questionnaire survey of the residents are summarized as follows: 1) The proportion of people over the age of 60 living on a low income is high and consists mostly of retired citizens who have lived in the transition zone, in their own homes, for an extended length of time 2) The condition of infrastructure in the transition zone is very poor, however, despite the housing deterioration, the internal repair and maintenance of houses is more satisfactory than their external appearance. 3) Residential satisfaction received high ratings in every category except pollution and housing price. This response appears to stem from the easy commute of residents as well as the ready availability of facilities in the city center. 4) In terms of residential satisfaction, the residents can be divided into two groups. The first, with a high satisfaction rate, consists mainly of senior citizens who possess both personal homes and a stable living, having resided in the city center for most of their lives. The second, with a lower satisfaction rate, is composed mostly of younger residents who have lived temporarily in inexpensive rental homes. As a results, the residential area in the transition zone of central Daegu does not appear to be a problematic area like the slum of the West, but instead a stable settlement for its residents.

• Journal of Distribution Science
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• v.8 no.3
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• pp.5-15
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• 2010

Business corporations have become specialized and on the basis of various interests try to strengthen their competitiveness through a cooperative system of purchase, distribution, service and IT technology. And an advanced Internet-based electronic commerce has witnessed explosive growth and a business-to-business (B2B) electronic commerce. Through E-marketplace. business corporations achieve such diverse utilities as expenditure curtailment, process reduction and prime cost reduction. And with business depression worldwide and soaring prices of materials, many business corporations consider the introduction of comprehensive purchase of MRO (maintenance, repair and operation) materials. The Purpose of this study was to examine the definition of B2B E-marketplace and the utilities of MRO commerce correctly focusing on an empirical analysis of cases of MRO supply and purchase business corporations. The indications acquired from this research results are as follows. Firstly, as for MRO integrated purchase under the characteristics of the market environment, it had to use the supplier obligatorily through the integrated purchase on the level of CEO's decision-making or the group rather than the voluntary will of the purchasing department or the procurement department. Secondly, as for the present B2B E-marketplace MRO purchase, the purchasing agency business has formed the mainstream, but it is aiming at the diversification of the benefit by supplementing/correcting the business model such as category type, mediation business type, MRO-type advancing in the store inclusive of the purchasing agency business, keeping pace with the potential market of MRO. Thirdly, as for analysis of the products, the purchaser wants more various products and assortment of goods than those of the present time, and also to be provided with the precise product information. Especially, as the importance of the product sourcing becomes high, the whole energy has been bestowed on acquirement of the excellent suppliers. Fourth, as for use of B2B E-marketplace MRO integrated purchasing system, there are the purchasing companies complaining the inconvenience even until now, and there is the demerit spending the long time during the image move and the process treatment. It shall try to shorten the searching time and the process treatment time as the system is centered on the purchaser. In order to enhance the efficiency of MRO E-marketplace purchase, followings must be considered: First, because the importance of product sources ever increases, an excellent supplier must be secured earnestly. Second, the time of process must be reduced focusing on purchasers. B2B E-marketplace will increase and diversify electronic commerce continuously. Through MRO E-marketplace, business corporations will reduce expenditure, achieve a transparent and speedy trade, and purchase products of fine quality, thus establishing a most effective market. In addition, in this study the investigator brings focus into MRO which has not been clearly discussed in the academic and business world so far and intensively highlights an indirect material-oriented expenditure curtailment effect. By taking all the aspects of supplier, purchaser and practical economical value into account, the investigator presents a strategic direction for the successful comprehensive purchase of B2B MRO.

• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.101-109
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• 2011

As climate change is becoming the main issue, various efforts are focused on saving building energy consumption both at home and abroad. In particular, it is very important to save energy by maintenance, repair and rehabilitation of existing multi-family housing complex, because energy consumption in residential buildings is not only forming a great part of gross energy consumption in Korea but the number of deteriorated complexes is also sharply increasing. However, energy saving is not considered as a main factor in decision making on rehabilitation project. Also, any supporting tool is not appropriately prepared in existing process. As the first step for development of decision support system on rehabilitation, this paper developed a breakdown structure, which makes clusters of multi-family housing complexes. Decision tree, one of data mining methods, was used to make clusters based on the characteristics and energy consumption data of multi-family housing complexes. Energy saving and CO2 reduction will be maximized by considering energy consumption during rehabilitation process of multi-family housing complex, based on these results and following research.

• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.11-18
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• 2013

Cement concrete pavement offers long-term service life and excellent applicability for heavy traffic. It is easier to purchase and more durable and economical than the asphalt pavement. However, it is difficult to repair and rehabilitate compared to the asphalt pavement when it comes to the maintenance problem. Since the crack is the main reason of the damage of concrete pavement, it is necessary to control the early and long-term crack in the concrete pavement. In this experimental study, the basic performance tests have been carried out to investigate the effect of hybrid fibers which were composed of micro fibers with small diameter and high aspect ratio and macro fibers with large diameter and low aspect ratio on the concrete pavement, in which lower water ratio and larger aggregates were used compared to the general concrete mixture. The test results showed that the flexural strength and toughness of concrete pavement mixture have been increased with the use of hybrid fibers in the concrete pavement mixture, even though they were less effective compared to the normal concrete mixture. It was found that the hybrid fibers were effective to control the early shrinkage of the concrete pavement which is one of the main reasons of the damage in the concrete pavement.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.45 no.4
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• pp.415-422
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• 2019

Human epidermal stem cells(ESCs) residing in the basement membrane of the skin have an important role in maintenance of skin homeostasis of epidermal layer. Although, ESCs provide new cells to repair damaged tissue in response to tissue injury, subsets of stem cells remain in the quiescent state protected from differentiation and senescence for prolonged survivals. In this perspective, the stem cell niche, which is specific microenvironment composed of niche cells and an extracellular matrix(ECM), supplies the relevant signal to save stem cells from microenvironmental damages. The expression of stemness marker on the surface of ESCs contributes to the attachment on their ECM of the basement membrane, which lead to growth potential and apoptotic resistance against environmental stimuli. In this study, we observed that UV irradiation, a major factor of environmental stimuli, reduced the expression of α2, β1 and α6 integrin in ESCs. Rhus Semialata M extract(RSE) showed inhibitory effect on the UVB-induced reduction of integrin expression. Furthermore, RSE could upregulate the expression of Col-IV and Laminin, which contribute to the attachment of ESCs. These results indicated that RSE could be a potent ingredient for the protection of ESCs from UV irradiation by increasing the expression of integrin and substrate ECM components at their niche.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1215-1224
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• 2013

Great efforts have been made worldwide to reduce the Green House Gas (GHG) emission following the "Kyoto Protocol" declared during the United Nations Framework Convention on Climate Change in 1997. Many industries have restructured to meet the standard set by the Protocol. However, no clear guidance has been established for the purpose of reducing the GHG emission in construction industry. In addition, no significant effort has been made to conserve the energy during construction activities. For more effective energy saving in construction industry, it is essential to collect data about energy consumption, quantity of environmental emissions and costs. However, most studies on sustainable construction have been concentrated on the use of equipment, maintenance and repair works during construction due to the difficulties of collecting such data. This study suggests a method to select the most environmentally friendly equipment combination for earthwork with comparing environmental loads and costs using the database of Life Cycle Inventory in the Ministry of Knowledge Economy and Ministry of Environment of Korea.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.5
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• pp.515-528
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• 2020

Underground concrete structures are usually designed to be used for decades, but in recent years, many of them are nearing their original life expectancy. As a result, it is necessary to promptly inspect and repair the structure, since it can cause lost of fundamental functions and bring unexpected problems. Therefore, personnel-based inspections and repairs have been underway for maintenance of underground structures, but nowadays, objective inspection technologies have been actively developed through the fusion of deep learning and image process. In particular, various researches have been conducted on developing a concrete crack detection algorithm based on supervised learning. Most of these studies requires a large amount of image data, especially, label images. In order to secure those images, it takes a lot of time and labor in reality. To resolve this problem, we introduce a method to increase the accuracy of crack area detection, improved by 0.25% on average by applying adversarial learning in this paper. The adversarial learning consists of a segmentation neural network and a discriminator neural network, and it is an algorithm that improves recognition performance by generating a virtual label image in a competitive structure. In this study, an efficient deep neural network learning method was proposed using this method, and it is expected to be used for accurate crack detection in the future.