• Journal of Korean Society of Water and Wastewater
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• v.26 no.5
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• pp.669-683
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• 2012

The water supply pipes are buried across wide range of areas, so it is hard to spot them using excavation and takes a large amount of expense. Thus, there is a high risk for direct research and application, accompanying many difficulties in implementation of them. Therefore, it is more economical and convenient to use indirect evaluation variables than direct evaluation of the buried pipes in assessing the degree of pipe deterioration. To assess the degree of pipe deterioration using the indirect evaluation variables, it should be done first to identify how and to what extent they affect the degree of deterioration. This study measured the evaluation variables for pipe deterioration using the pipe endoscope and analyzed the measurement results and the degree of impact on the pipes. In addition, this study attempted to evaluate the adequateness of the pipe deterioration evaluation using the indirect variables based on the analysis results. The evaluation variables measured through the pipe endoscope were the thickness of sediments, size of scale, degree of desquamation and condition of connections. For the indirect evaluation variables, the data such as the property data from GIS pipe network map as well as the material, diameter, age and pipe lining material of the pipe, road type, leakage frequency, average water velocity and water pressure using the leakage repair records was collected. Using the collected data, this study comparatively analyzed the indirect evaluation variables for the degree of pipe deterioration and the results from the pipe endoscope to choose appropriate variables for pipe deterioration evaluation and calculated the weights of the indirect variables on the degree of deterioration. The results showed that the order of the impact of indirect variables on deterioration was pipe age > pipe lining material > road type > leakage frequency > average water velocity with their weights of 0.45, 0.20, 0.15, 0.10, and 0.10, respectively. Conclusively, the results suggest that the measures of sediment thickness, scale size, degree of desquamation and condition of connections are appropriate for the evaluation of pipe deterioration and sufficient for the analysis of the impact of the indirect variables on deterioration.

• Journal of the Korean Wood Science and Technology
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• v.32 no.3
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• pp.33-41
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• 2004

In ancient wooden structures, the mechanical properties of the structural members have been reduced by time-dependent degradations such as fatigue or creep. Also, the external and internal deterioration was caused by environmental condition, fungi, bacteria, or insect, and then reduced the quality of structural members. However, the previous methods for evaluating the deterioration have been mainly depended on the visual inspection. In this study, therefore, ultrasonic stress wave test, accelerometer stress wave test were used to evaluate the deterioration of structural wood members in ancient wooden structures. Based on the results, the quantitative criteria of stress wave transmitted velocity were proposed to evaluate the deterioration of structural member. The proposed criteria were related to the degree of deterioration. In accelerometer stress wave, the criteria of deterioration of wave reciprocal velocity was below 1800 ㎲/m at incipient deterioration (below 12% ratio of deterioration), between 1800 and 2200 ㎲/m at moderate deterioration (12~17%) and above 2200 ㎲/m at severe deterioration (above 17%). The ultrasonic stress wave, the criteria of deterioration were 800 and 950 ㎲/m at below 8% and above 15% of the degree of deterioration respectively.

• Journal of the Korean Institute of Educational Facilities
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• v.24 no.6
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• pp.11-18
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• 2017

Education facilities have much affect to make a good condition for the learning environment. Therefore, various approaches have been conducted to improve the physical, social and educational achievement. Especially, the physical aspect is very important to get rid of the building defect and improve the student their learning environment. For these, it needs to explain the performance and function of components and materials, which is linked with the deterioration degree. The deterioration degree is a imperative factor to make a decision whether the component would be repaired or not and to provide the repair scope of its component. In this paper, it aimed at making the deterioration degree model of roof proof under the hypothesis of which deterioration degree would be equal the repair cost at this time. Results of the study are shown that first, the $3^{rd}$ function is most proper to explain the deterioration degree model among 11 functions in view of resulted statistics. Second, the inflection of deterioration is shown at 15yr of the elementary school and 13yr of the middle and high school. This study has a limit of disclassification of the component or materials and it is, therefore, favorable to include the classification of waterproof material and work. These results would make a change from the breakdown maintenance to preventive maintenance and give a decent the learning environment for student.

• Journal of Korea Water Resources Association
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• v.36 no.1
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• pp.61-74
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• 2003

This study(II) apply to the A city by using the optimal rehabilitation model based on the deterioration prediction of the water distribution system proposed the study(I). The deterioration prediction model divides factors into 14 factors with digging and experiment and 9 factor without digging and experiment and calculate the deterioration degree. The application results of the deterioration prediction model show that a difference of the deterioration degree according to factor numbers is within 1~2%. Also, the model can predict the deterioration degree of each pipe without digging and experiment. The optimal rehabilitation model is divided into the optimal residual durability of each deterioration factor and budget constraint or not. The application result is as follow: the rehabilitation time and cost increase according to the increasing of the optimal residual durability. When compared the model with budget constraint and model without budget constraint, the former model increase the cost of total contents. In case of budget constraint, the increasing tendency is concluded that the pipe rehabilitation is executed in same budget every year in condition that every rehabilitation cost do not exceed the every year budget within the optimal residual durability.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.293-298
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• 2016

Recently, interests for maintenance of transmission tower are increasing to extend life of structures and reduce maintenance cost. However, existing classical diagnosis method of corrosion deteriorated degree on the transmission tower steel members, visual inspection, has a problem that error often due to difference of inspector's individual knowledge and experience. In order to solve the problem, this study carried out to develop the corrosion deterioration inspection tool for transmission tower steel members. This tool is composed of camera equipment and computer-aided diagnosis system. We standardized the photographing method by camera equipment to obtain suitable pictures for image processing. Diagnosis system was designed to evaluate automatically degree of corrosion deterioration for member of transmission tower on the basis of the RGB color image processing techniques. It is anticipated that developed the corrosion deterioration inspection tool will be very helpful in decision of optimal maintenance time for transmission tower corrosion.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.04a
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• pp.37-43
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• 1990

This paper develops practical models and methods for the assessment of safety and rating of damaged and/or deteriorated bridges by incorporating a system identification technique for the explicit inclusion of the degree of deterioration or damage and of the actual bridge response. And, based on the proposed model, reliability-based rating methods are proposed as LRFR(Load and Resistance Factor Rating) and system reliability-index rating criteria. The proposed limit state model explicitly accounts for the degree of deterioration or damage in terms of the damage and response factors. The damage factor in the paper is proposed as the ratio of the current stiffness to the intact stiffness. Based on the observation and the results of applications to existing bridges, it may be concluded that the proposed rating models, which explicitly account for the uncertainties and the effects of degree of deterioration or damage based on the system identification technique, provide more realistic and consistent safety-assessment and capacity-rating.

• Journal of Korea Water Resources Association
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• v.36 no.1
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• pp.45-59
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• 2003

The method in this study, which is more efficiency than the existing method, propose the optimal rehabilitation model based on the deterioration prediction of the laying pipe by using the deterioration survey method of the water distribution system. The deterioration prediction model divides the deterioration degree of each pipe into 5 degree by using the probabilistic neural network. Also, the optimal residual durability is estimated by the calculated deterioration degree in each pipe and pipe diameter. The optimal rehabilitation model by integer programming base on the shortest path can calculate a time and cost of maintenance, rehabilitation, and replacement. Also, the model is divided into budget constraint and no budget constraint. Consequently, the model proposed by the study can be utilized as the quantitative method for the management of the water distribution system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.341-347
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• 2008

Among coating systems used for steel bridge coatings on highway such as red lead-pigmented alkyd, chlorinated rubber, waterborne inorganic zinc, inorganic zinc/epoxy/urethane and inorganic zinc/epoxy/fluororesin, evaluation of deterioration degree and prediction of lifetime through regression analysis were carried out for coating systems widely used and grossly degraded. For evaluation of deterioration degree, 75 bridges on highway were selected, and evaluations were carried out according to point offering method regulated by Guideline of maintenance coating for steel bridges used in Korea Expressway Corporation. Lifetime prediction results showed 13.0~13.3 years for the whole nation, 11.8 years for urban and industrial region in the metropolitan area, 13.2 years for rural region except the metropolitan area, 13.5~13.7 years for chlorinated rubber coating systems, and 12.86 years for red lead-pigmented alkyd systems. For prediction of the rest life of coating, we tried to execute parallel translations of standard deterioration curve to current life and deterioration degree for both x and y axes, and it was thought that parallel translation for x axis corresponded to deterioration aspects in actual environment. Maximum and minimum equations were derived from standard deterioration equation by adding and subtracting error values deduced in regression analysis to/from each coefficient in order to establish maintenance coating criteria for overall steel bridges on highway. Whole domain was divided into 8 parts in order to predict the rest life of coating and optimum time of maintenance coating, and maintenance coating criteria for each 8 domains were presented.

• 보존과학연구
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• s.7
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• pp.246-264
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• 1986

Micoromorphological alterations of sea-waterlogged woods by marinemicro-oragnisms were investigated by the light and scanning electron microscopy as a part of serial investigations on the shipwrecked materials which were excavated at the sea shore of Wando-Kun, southern coast of Korea in 1984.Deterioration of sea-waterlogged wood by marine microorganisms were varied with the wood species. The degree of deterioration even in the same wood specieswas different according to the part where it was in mud of sea-water. However, the resistance of Torreya nucifera over the marine organisms was marked. Deterioration in cell wall may be classified into three types; thinning of cell wall, separation of secondary wall from compound middle lamella and tunneling of cell wall. Thinning and separation were frequently observed, while the tunneling was rare. Among the wood cell elements of hardwoods, vessel wall was the least deteriorated. The difference degree of degradation of cell wall constituents and the accumulation of inorganic substances in cell lumen indicate that some factors to be considered for the conservation treatment were discussed. The kinds of marine microorganisms invading and/or inhabiting in wrecked wooden ship were also discussed.

• Journal of Korean Society of Water and Wastewater
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• v.16 no.6
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• pp.686-699
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• 2002

The purpose of this study is to estimate deterioration factors and weighting factors in pipe network which each local self-governments takes rehabilitation and replacement work present time. Deterioration factors in pipe network are able to effected of specific province or location related with water supply. Most of water supply pipes are laid under the ground, it is hard to quantify deterioration degree of water system. Moreover, the timing and economic limitation and insufficient information on the spot survey gives a difficulty to look over how old water supply system is. Accordingly, this study collects and analyses five data as the laying environment, visual analysis, analysis of soil contents, analysis of pipe material, and questionary survey data in water pipe of A city. The deterioration factor estimates 14 factors with excavation and experimental analysis and 9 factors without excavation and experimental analysis. Also, the weighting factors are estimated by using the multiple linear regressions and the linear programming. The estimated deterioration factor and weighting results are compared the analysis result of visual, pipe material, and soil contents with the Probabilistic Neural Network Model. Consequently, the model results of estimated 9 factors in this study and 14 factors show the 1-2% difference. The result show that the proposed model could be used to decide the deterioration condition of pipe line with real excavation and experimental analysis.