• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.45-56
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• 1999

There have been many coal mines abandoned since late 1980s in Korea. Due to the abandoned mines, there have been ground subsidences in some area where are under ground reinforcement works now. So, this study shows the general phenomena of mining subsidence and the procedure of ground reinforcement. In general the procedure for ground reinforcement is as below, 1) obtaining information from inquiries and observations, 2) satellite image analysis and surface geological mapping, 3) analysis of maps of coal mines, 4) geophysical survey and boring test and 5) selection of reinforcement method. The case of reinforcement design at Chul-am area, Kangwon Province is introduced in this article.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.761-766
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• 2002

This paper was peformed to verify the effect that granulated blast furnace slag gets in reinforcement corrosion resistance about chloride ion that invade from outside. An experiment accelerated for the reinforcement corrosion through repeat of brine digestion and dry. Reinforcement corrosion investigated half cell potential method of measurement by ASTM C876 and corrosion area ratio. If granulated blast furnace slag metathesis ratio is high generally that looked the corrosion of reinforcement decreasing as a result that evaluate reinforcement corrosion by ASTM C876 canon in this research. It showed high resistance about reinforcement corrosion that use normal portland cement and increase the metathesis rate of granulated blast furnace slag, as a result that evaluate metathesis rate effect of granulated blast furnace slag according to cement kind. when the test piece split destroying, area rate of reinforcement corrosion showed about result of half cell potential measurement.

• Earthquakes and Structures
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• v.22 no.1
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• pp.39-51
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• 2022

The axial compression behavior of nine self-compacting concrete columns confined with CFRP-PVC spirals was studied. Three parameters of spiral reinforcement spacing, spiral reinforcement diameter and height diameter ratio were studied. The test results show that the CFRP strip and PVC tube are destroyed first, and the spiral reinforcement and longitudinal reinforcement yield. The results show that with the increase of spiral reinforcement spacing, the peak bearing capacity decreases, but the ductility increases; with the increase of spiral reinforcement diameter, the peak bearing capacity increases, but has little effect on ductility, and the specimen with the ratio of height to diameter of 7.5 has the best mechanical properties. According to the reasonable constitutive relation of material, the finite element model of axial compression is established. Based on the verified finite element model, the stress mechanism is revealed. Finally, the composite constraint model and bearing capacity calculation method are proposed.

• Journal of the Korean Society for Railway
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• v.10 no.2 s.39
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• pp.186-194
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• 2007

This study was performed to compare the load-carrying capacities of the reinforced concrete structure between the carbon fiber adhesion reinforcement method and the external post-tensioning method and further estimate the effective stress of the reinforced material by analyzing the experimental reinforcing effect of each method and the behavior resulting from each method. As a result, it was found out that the effective stress of the carbon fiber reinforcement according to the carbon fiber adhesion reinforcement method had an unexpected value, and also, bearing of the stress was found to be far from sharing thereof. That is to say, while the carbon fiber was bearing the whole stress to some limits, it got to be momentarily ruptured as soon as it went beyond such limits. On the other hand, the external post-tensioning method has the advantage of inducing an initial effective stress by introducing a strain, and thus, it was found that behavior or bearing of the stress was also found to be a solid behavior of the steel wire. This method was also found to be more efficient and excellent than the carbon fiber adhesion reinforcement method in the reinforcing effect or securing the effective stress. Accordingly, we were to discuss the effective stress as comparatively examined, focusing on deriving of the more enhanced reinforcing effect on the basis of the experiment to which the field characteristic is added.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1300-1304
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• 2003

The following paper deals with a control problem of a mobile robot in home network environment. The home network causes the mobile robot to communicate with sensors to get the sensor measurements and to be adapted to the environment changes. To get the improved performance of control of a mobile robot in spite of the change in home network environment, we use the fuzzy inference system with multiple reward reinforcement learning. The multiple reward reinforcement learning enables the mobile robot to consider the multiple control objectives and adapt itself to the change in home network environment. Multiple reward fuzzy Q-learning method is proposed for the multiple reward reinforcement learning. Multiple Q-values are considered and max-min optimization is applied to get the improved fuzzy rule. To show the effectiveness of the proposed method, some simulation results are given, which are performed in home network environment, i.e., LAN, wireless LAN, etc.

• Structural Engineering and Mechanics
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• v.75 no.4
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• pp.455-464
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• 2020

Reinforcement corrosion is one of the major problems in the durability of reinforced concrete structures exposed to aggressive environments. Deterioration caused by reinforcement corrosion reduces the durability and the safety margin of concrete structures, causing excessive costs in managing these structures safely. This paper aims to investigate the effects of reinforcement corrosion on the load bearing capacity deterioration of the corroded reinforced concrete structures. A new analytical method is proposed to predict the crack growth of cover concrete and evaluate the residual strength of concrete structures with corroded reinforcement failing in bond. The structural performance indicators, such as concrete crack growth and flexural strength deterioration rate, are assumed to be a stochastic process for lifetime distribution modelling of structural performance deterioration over time during the life cycle. The Weibull life evolution model is employed for analysing lifetime reliability and estimating remaining useful life of the corroded concrete structures. The results for the worked example show that the proposed approach can provide a reliable method for lifetime performance assessment of the corroded reinforced concrete structures.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.5
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• pp.221-230
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• 2014

The purpose of this study is to investigate the seismic performance of hollow RC bridge columns with reinforcement details for material quantity reduction. The proposed reinforcement details provide economy, are rational and shorthen the construction periods. The accuracy and objectivity of the assessment process can be enhanced by using a sophisticated nonlinear finite element analysis program. Solution of the equations of motion is obtained by numerical integration using Hilber-Hughes-Taylor (HHT) algorithm. The adopted numerical method gives a realistic prediction of seismic performance throughout the input ground motions for several test specimens investigated. As a result, the proposed reinforcement details for material quantity reduction develop equal performance to that required for existing reinforcement details.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.03a
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• pp.81-84
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• 1998

Genetic Algorithms (GAs) are stochastic algorithms whose search methods model some natural phenomena. The procedure of GAs may be divided into two sub-procedures : Operation and Selection. Chromosomes can produce new offspring by means of operation, and the fitter chromosomes can produce more offspring than the less fit ones by means of selection. However, operation which is executed randomly and has some limits to its execution can not guarantee to produce fitter chromosomes. Thus, we propose a method which gives a directional information to the genetic operator by reinforcement learning. It can be achived by using neural networks to apply reinforcement learning to the genetic operator. We use the amount of fitness change which can be considered as reinforcement signal to calcualte the error terms for the output units. Then the weights are updated using backpropagtion algorithm. The performance improvement of GAs using reinforcement learning can be measured by applying the pr posed method to GA-hard problem.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.205-212
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• 2002

Carbonate rocks such as limestone are susceptible to solution and show numerous solution cavities. For the construction of the structures such as bridge foundations and tunnel on the limestone cavities, the geological unconformities developed in the bed rocks, cavity systems and the filling types of solution deposits should be surveyed and analyzed. And also, the stability of structures on the limestone cavities must be taken into consideration in the view of the geotechnical engineering. As a result of analysis of the foundation settlement, an economic and effective reinforcement method is to be proposed and the construction by the proposed method is to be accompanied with verification of reinforcement effect. This paper is a case study of design and construction for the reinforcement of bridge foundations on the limestone cavity covered with thick bedded colluvial soils.

• Journal of Industrial Technology
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• v.41 no.1
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• pp.7-13
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• 2021

Fiber-reinforced polymer reinforcement or polyurea reinforcement techniques are applied to strengthen unreinforced masonry walls (UMWs). The out-of-plane reinforcing effect of sprayed glass fiber-reinforced polyurea (GFRPU), which is a composite elastomer made of polyurea and milled glass fibers on UMW, is experimentally verified. The out-of-plane strengths and ductile behaviors based on various coating shapes are compared in this study. An empirical formula to describe the degree of reinforcement on the out-of-plane strength of the UMW is derived based on the experimental results. It is reported that the peak load-carrying capacity, ductility, and energy absorption capacity gradually improve with an increase in the strengthening degree or area. Compared with the existing masonry wall reinforcement method, the GFRPU technique is a construction method that can help improve the safety performance along with ease of construction and economic efficiency.