• Journal of the Korea Institute of Building Construction
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• v.4 no.1
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• pp.119-126
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• 2004

Generally, reinforced concrete is one of the most commonly used structural materials and it prevents corrosion of steel bar by high pH of interior, But, as time elapsed, reinforced concrete structure become deteriorated by many of combined deterioration factors and environmental conditions. And, there are large number of deteriorate mechanism of the reinforced concrete structure and it acts complexly. It is recognized that steel bar corrosion is the main distress behind the present concern regarding concrete durability. In this study, to institute combined deterioration environments, established acceleration condition and cycle for combined deterioration environments has a resemblance to environments which are real structures placed. After that to confirm corrosion properties of reinforced concrete due to permeability with covering depth and types of surface cover under combined deterioration environments, measured carbonation velocity coefficients, chloride ion diffusion coefficients, water absorption coefficients, air permeability coefficients and electric potential, corrosion area ratio, weight reduction, corrosion velocity of steel bar. The results showed that an increase in age also decrease carbonation velocity coefficients, increase Chloride ion diffusion coefficients and increases water absorption coefficients. As well, an increase in age also increases corrosion of steel bar. Data on the development of corrosion velocity of steel bar with types of surface cover made with none, organic B, organic A, inorganic B, and inorganic A is shown. As well, permeability and corrosion velocity of steel bar with covering depth is superior to 10mm than 20mm. And it is confirmed permeability and corrosion properties of steel bar are closely related.

• Magazine of the Korea Concrete Institute
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• v.22 no.4
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• pp.28-32
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• 2010

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.64-72
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• 2015

Risk Based Inspection (RBI) Period was proposed for highway bridges in Korea. Hazard factors affecting bridge condition deterioration were found by analyzing condition data from Highway Bridge Management System (HBMS). Certain level of correlations between those factors and condition deterioration were found. They are used to evaluate hazard score. Summarizing several hazard factors, final hazard is classified as three level;high, moderate, low. Vulnerability is assessed only by the current state of bridge. Then, risk matrix is suggested for inspection periods. Inspection periods of the bridges with grade C, D, and E are maintained the same as before. But, those of grade A and B with moderate and high hazard score are elongated to maximum 6 years while the maximum inspection period is three years at present. By adjusting inspection period according to risk assessment, it was shown that 27% of average inspection manpower can be saved.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.177-186
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• 2005

The latest concrete structure has showed that the deterioration of durability has been increased by the damage from salt, carbonization, freezing & thawing and the others. Therefore, the measures for the concrete which has deteriorated durability have been taken. Among them, it has been often used that surface treatment which cuts off the deterioration factors of durability by protecting the surface of concrete. However, troubles such as fracture and rupture in the repair layer have been reported as time goes by due to the difference between the organic repair material like epoxy and concrete properties. Researchers have been developing the repair material which can cut off the deterioration factors of durability such as $CO_2$ gas, chloride ion and water by making the formation of concrete elaborate through the reaction with calcium ion when the surface improving agent is coated on the concrete. The main ingredient of that is inorganic substance which is the same as the concrete property. This study was evaluated the surface improving agent for permeability, watertightness, air-permeability, chemical resistance and elution resistance. As a result, it has been reported that the surface improving agent improves watertightness and air-permeability by penetration more than 10mm within concrete. Therefore, it is concluded that the surface improving agent developed in this research prevents deterioration of concrete durability when it is coated on the concrete structure.

• International Journal of Reliability and Applications
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• v.5 no.4
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• pp.115-128
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• 2004

Reliability of a power supply timber pole depends on complex combination of age, environmental factors involved in deterioration process ans inspection and maintenance actions influencing reliability and safety. In this paper soil and human factors are identified, models have been developed and analyzed for optimal maintenence decisions related to electrical power supply timber poles.

• Computers and Concrete
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• v.15 no.6
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• pp.879-902
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• 2015

The remaining service life (RSL) of buildings has been an important issue in the field of building and facility management, and its development is also one of the essential factors for achieving sustainable infrastructure. Since the estimation of RSL of buildings is heavily affected by the subjectivity of individual inspector or engineer, much effort has been placed in the development of a rational method that can estimate the RSL of existing buildings more quantitatively using objective measurement indices. Various uncertain factors contribute to the deterioration of the structural performance of buildings, and most of the common building structures are constructed not with a single structural member but with various types of structural components (e.g., beams, slabs, and columns) in multistory floors. Most existing RSL estimation methods, however, consider only an individual factor. In this study, an estimation method for RSL of concrete buildings is presented by utilizing a fuzzy theory to consider the effects of multiple influencing factors on the deterioration of durability (e.g., concrete carbonation, chloride attack, sulfate attack), as well as the current structural condition (or damage level) of buildings.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.220.2-220.2
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• 2011

Biodiesel and biodiesel blend fuel are receiving increasing attention as alternative fuels for diesel engines without substantial modifications. Biodiesel fuels and blending have been widely studied and applied in diesel engine because of biodiesel's lower sulfur, lower aromatic hydrocarbon and higher oxygen content. Biodiesels have the potential to be oxidized in different condition. It has reported that oxidation deterioration of biodiesel is different in the condition of storage and oxidation causes chemical property change of methyl esters. Sunlight intensity, temperature, material of container and contact surface with oxygen are key dominant factors accelerating oxidation deterioration. In this study, we chose temperature among key oxidation conditions and metal container filled with biodiesel was heated at about $110^{\circ}C$ for 10 days in order to accelerate oxidation deterioration. To better understand the effect of biodiesel blends on emission, steady state tests were conducted on a heavy duty diesel engine. The engine was fueled with Ultra Low Sulphur Diesel(ULSD), a blend of 10% and 20%(BD10, BD20) on volumetric basis, equipped with a common rail direct injection system and turbocharger, lives up to the requirements of EURO 3. The experimental results show that the blend fuel of normal biodiesel with BD10 and BD20 increased NOx. The result of PM was similar to diesel fuel on BD10, but the result of PM on BD20 was increased about 63% more than its of diesel. The blend fuel of Oxidation biodiesel with BD10 and BD20 increased NOx as the results of normal biodiesel. But PM was all increased on BD10 and BD20. Especially THC was extremely increased when test fuel contains biodiesel about 140% more than its of diesel. Through this study, we knew that oxidation deterioration of biodiesel affects emission of diesel engine.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1096-1101
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• 2014

This study (II) has appled the new assessment model of large-diameter pipe deterioration proposed by the study (I) to the metropolitan multi-regional water supply system (1st phase). In the total 30 pipelines, 24 and 27 pipelines were required for improvement as results from the existing evaluation methods 1995 and 2002, respectively. The assessment results were almost similar in the new developed model and the existing methods. It is founded that the new simple model developed in this study can produce reliable results, consistent with those from the existing methods requiring many factors for a pipe deterioration assessment. It is therefore expected that the new model would be helpful in practical applications of a pipe deterioration assessment since it can save both temporal and economic costs for experiments and analysis, as compared with existing assessment methods.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.181-189
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• 2003

Because of the gravitation of population toward large cities, a number of masonry buildings have been constructed since 1960. They have been rapidly deteriorated as time passed by. Therefore the purpose of this paper is to present basic data on timeworn masonry buildings which have been managed by metropolitan government and to analyse their deterioration factors. And then, the results of this paper can be used to establish the policy of managing timeworn masonry buildings. According to this study, the crack of masonry wall is the most effective deterioration factor and timeworn masonry buildings have a problem with foundation. The structure grade have an interrelation with occupancy type more than building age. Also, the longer building age becomes, the sooner deterioration speeds. A timeworn masonry building is in urgent need of reinforcement on a thirty-year period of building age.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.5
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• pp.135-140
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• 2024

DC capacitors used in PV inverters have a relatively short lifespan compared to other power semiconductor devices and have a failure rate of 60%, making them the most vulnerable among the elements that make up a power conversion system (PCS). In addition, the lifespan of the capacitor varies depending on environmental factors, greatly affecting the lifespan and operating conditions of PV inverters and PV power generation systems. Therefore, research is needed on the development of inverter deterioration diagnostic sensor technology optimized for building-integrated and general PV power generation systems and the development of bypass compensation capacitor modules that can maintain the efficiency of the inverter in the event of a failure. Based on this research, the DC capacitor deterioration diagnosis module inside the PV inverter measures the capacity of the actual internal components and can check the trend information of the deterioration state in the long term, enabling rapid response to fires. In addition, it seeks to improve the efficiency of power generation facilities and reduce carbon emissions, and prevents electrical fires, allowing the PV power generation system to be maintained in optimal condition.