• Journal of the Korean GEO-environmental Society
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• v.5 no.3
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• pp.31-39
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• 2004

The bored pile is widely used as a low noise and vibration piling method in Korea. However, there is design tendency to minimize the friction capacity of the bored pile because of uncertainty and the quality control specification is not set up. This research analysed the strength characteristics of cement paste after the uniaxial compression test with various condition. Test results show that the compressive strength of cement paste with w/c=0.83 was up to $156.0kgf/cm^2$, and the lower w/c ratio and the longer age, the strength of cement paste increased. Also the higher soil mixing ratio, the strength of soil cement decreased, and too high soil mixing ratio caused the malfuction of soil cement. Also this research analysed the 188 dynamic pile test results which were performed before and after hardening of cement paste. Analysis result showed that the average ultimate unit friction capacity was $9.1tf/m^2$ and this result surpassed the common design criteria of the bored pile.

• Journal of the Society of Disaster Information
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• v.16 no.3
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• pp.472-478
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• 2020

Purpose: The purpose of the study is to help economic and safe construction by accurately predicting the initial strength of high-strength concrete (70MPa) for each type of cement, securing reliability of concrete quality, and drawing accurately the timing of form deformed, tensioning time of PS concrete, and openning of traffic after road repair with maturity. Method: Calculate the maturity by measuring the hydration heat with cement type for each age, and measure the strength of concrete with age to predict the strength corresponding to the any maturity. Result: In estimating the time required for traffic opening in road repair, ASTM C1074 was theoretically estimated at 16.4 hours for high-strength concrete, but in this study, maturity was calculated at 307, 14.4 hours for OPC and maturity at 2700, 34 hours for LHPC and maturity 200, 8 hours for ESPC. Conclusion: The timing of form deformed of structures using high-strength concrete and the opening of traffic of road repair may be much faster than in the case of concrete using OPC below the design basis strength 40MPa applied by ACI Committee 347.

• The Journal of Engineering Research
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• v.6 no.1
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• pp.15-27
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• 2004

The first aim of mass product of glass in Automatic bottle glass industry is to decrease the cost and to increase the quality. Second, the cullet is how widely used to save the energy and reducing of ecomaterials. However the physical and chemical properties of Soda-lime glass would be come true at the lower than 2% $Al_2 O_3$. Unfortunately the $Al_2 O_3$ contents of domestic silica is greater than 4% Since small glass class than 200ml bottle is made in domestic silica the producting efficiency would be decreased due to the defect such as cord, knot, devitrite, pore etc. There are many problems such as devitrifiacation and deteriorated effect on production in glass industry became of increasing of plate glass cullet. It is tried to solve these kinds of problems using various analysing methods in this experiments.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.1
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• pp.77-86
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• 2006

Although the adverse critisism have been continued that the concrete lining need or not, most tunnel engineer agree that the concrete lining needs to increase the tunnel safety To establish the concrete lining's quality improvement method, we grasp the basic problems in lining construction process and propose the lining construction methods to increase the concrete quality This paper present a reason of initial crack occurrence in the large section tunnel (4 lane wide span tunnel), lining and an improved method for crack minimization in construction process. It is also verified verify that the proposed method can give qualified concrete lining by carrying out the concrete injection model test and the numerical analysis of concrete flow.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.1
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• pp.17-24
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• 2008

Many problems exist in the current cast in place concrete lining used in domestic tunnel construction. Especially, the crack of tunnel lining brings about a social and economic problem. It has a lot of influence on stability of structure and the fine finish of lining. So enormous repair-work and reinforcement of tunnel lining could occur an running out of government's budget. In our country, there are domestic production enterprises which produce a special pre-cast concrete product, but the technical level of them is still far behind compared to developed countries. Also, optimum steam coring method is important for the production of high quality product. But there is no regulation of steam curing method in our country. This study is to investigate the properties of PC panel according to the variation of steam curing conditions such as presteaming time and rate of temperature rise. The result shows that the optimum presteaming time of steam curing method in PC panel is more than 1 hour and the desirable rate of temperature in curing chamber is about $20^{\circ}C/hr$.

• Journal of the Society of Disaster Information
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• v.10 no.4
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• pp.566-571
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• 2014

Recently, with concentrated social and engineering interests on durability, diversified subsequent researches have been progressed. The Chloride-induced corrosion, carbonation, freeze-thaw etc, deterioration factors of concrete act to concrete not privately but complexly, Fly ash is most frequently used admixture which is using a reduction method of deterioration. And the fly ash effects on improvement of durability with enhancement of fluidity, decrease of crack with reduction of hydration heat, promotion of long-age strength and have a economic advantage which replaces cement as a binding material. But, fly ash have different qualities and occasionally reduce the durability and strength by adhesion of AE admixture with unburned carbon powder etc. In this study, the experiments will take about various replacement ratio of fly ash concrete, and will analyze, consider the results, after these will verify applicability and validity as admixture and binding material.

• Journal of the Korean GEO-environmental Society
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• v.4 no.2
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• pp.47-56
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• 2003

The production of industrial wastes have increased due to the growth of population and industrial development. Among these wastes, especially amount of paper ash has been increased year after year. If it is possible to reuse industrial wastes, it will be beneficial not only economically but also environmentally. In this study, the possibility of the utilization of paper ash were investigated as a construction materials through a series of laboratory testing carried out to evaluate physical properties, compaction, consolidation, permeability and compressive strength characteristics. Concrete bricks with replacement ratio of paper ash at 2, 4, 6, 8, 10, 12, 14, 16, 18, 20%, and clayey bricks with replacement ratio of paper ash at 5, 10, 15, 20, 25, 30% were used in the test in order to evaluate its quality. As a result of tests, it were shown that the maximum replacement ratio of paper ash satisfying the quality standards of concrete bricks and clayey bricks were 11.5% and 12%, respectively.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.2 s.25
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• pp.7-12
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• 2007

This study has been conducted to present reform recommendations for Standardization of Construction Materials, based on a study on the Investigation of Demander's Consciousness for Construction Materials Quality and Information Standardization in Korea. Upon investigation, it was found that the quality of Korea Industrial Standards (KS) was given 67 points (out of 100) by respondents. In addition, 38% of the respondents showed that they had problems with a lack of Standardized Information. Good examples were found to be non-standardized materials, e.g. admixtures, waterproof agents, reinforcing fibers, concrete, aggregates, adhesives, wood, temporary materials, thermal-insulating materials, etc. Upon results from the investigation of demander's consciousness for infrastructure of standardization of information, 71.2% of respondents thought that it is necessary to informatize construction materials. They made following demands on the informatization to be, in order: Quality, Standard, Price (Cost), Operation, Drawing, Law, and Information.

• Journal of the Society of Disaster Information
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• v.7 no.3
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• pp.220-228
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• 2011

Disaster sign data is confirmed data by the experts to the collected data from web and users. In this paper, we focused to make the risk scores to the data based on ontology technology. To analyse the data, first of all, we defined the ontological structure for 4 kinds of disaster types which consists of the bridges, workplaces, buildings, and walls. Base on the ontologies, collected the accidents examples, and then extract the risk rules from the examples. The rules are adjusted with frequencies and weights, and managed to the ontology DB. The rules apply to the disaster sign data, and then calculates the risk scores. It plays role of the index to the risk rates. The disaster sign data management system was implemented and the rules were verified to the system. Because the quality of the risk scores to the disaster sign data depends on the data of the accidents examples's qualities, we assure that the system's performance will be monotonic increasing following up the data upgrades. Continuously, data management is needed. Also the quality control of the rules are needed.

• Journal of the Society of Disaster Information
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• v.7 no.2
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• pp.87-95
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• 2011

The skid resistant of pavement surface is an important parameter since it is directly related to the traffic safety under moving vehicular loads. In particular, it should be considered as a major factor in pavement performance evaluations to reduce the traffic accident from vehicular sliding. In this study, a portable and an automatic skid resistance tests were used to evaluate the skid resistances of the in-situ pavements. The test results showed that the skid resistance of the conventional dense graded pavement was more noticeable than the other pavement types such as the drainage pavement and the stone mastic asphalt(SMA) pavement as the service life of pavement was increased.