• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.4
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• pp.147-155
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• 2019

In this study, flexural tests of granite reinforced with titanium metal rods were carried out to repair and restore the damaged stone-made cultural heritage, the Stone Pagoda of the Mireuksa Temple Site. A total of twelve specimens were tested. The primary test parameters are the reinforcement ratio and the location of the reinforcement. For restoration, epoxy resin was used for joining the separated stones, and titanium metal rods were used for structural reinforcement. Test results showed that the flexural failure took place in specimens with a reinforcement ratio of 0.8% or less, and shear failure occurred when the reinforcement ratio was 1.68% or more. The peak load of the reinforced stone was found to be highly related to the reinforcement ratio. The peak load increased with increasing the reinforcement ratio. Also, the flexural behaviors of the reinforced stones were affected by the location of the reinforcement. Based on the test results, this study recommends the reinforcement ratio of the reinforced granite to induce ductile behavior.

• Journal of the Korean GEO-environmental Society
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• v.18 no.3
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• pp.31-38
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• 2017

The purpose of this study is to propose a chart that can easily estimate the seismic failure probability of small and medium sized earthfill dams with little geotechnical information. By considering the existing method and procedure for estimating the seismic failure probability of a dam, the zero seismic failure probability curve, on which the seismic probability is zero regardless of the geotechnical properties of the dam, was determined in the form of hyperbola in the dam height and freeboard ratio plane. It was confirmed that the dam height-freeboard ratio distribution pattern of the Korean small and medium sized dams was shaped like a hyperbola like the zero seismic failure probability curve. Therefore, a estimation chart was constructed in which a number of seismic failure probability contours are represented by a number of hyperbolas at regular intervals in the dam height-freeboard ratio plane. The proposed chart was applied to the calculation of the seismic failure probability of two small and midium sized dams with relatively well-managed geotechnical properties and the validity of the chart was confirmed by comparison with the results obtained by the existing procedures and methods. In the future, the proposed chart is expected to be useful in considering investment priorities for maintenance and reinforcement of small and medium sized dams in preparation for earthquakes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.275-284
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• 2021

Survival analysis was used to analyze whether there is a difference in the effect of leverage on corporate failure according to the firm size. A total of 25,250 (year-company) companies listed on the Korea Stock Exchange and KOSDAQ market from 1999 to 2019 were analyzed. First, the increase in leverage generally acts as a factor that increases the possibility of corporate failure. On the other hand, the increase in the trade payable ratio lowered the possibility of failure of the company. The increase in corporate trade payable was perceived as a factor in reducing the possibility of corporate failure because it was considered the active development of business activities or active use of interest-free debt rather than leading to an increase in corporate risk. Second, a higher leverage ratio and trade payable ratio in large firms lowered the possibility of corporate failure. In the SMEs, all types of leverage increases are a factor that increases corporate failure. Overall, the effect of leverage on corporate failure differs according to the size of the company.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.567-572
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• 1998

Structural behavior of R/C deep beams was investigated and compared to those of specimens with CFRP Grids. Test results show that the crushing of compression strut for the unstrengthened R/C deep beams is changed to the group of several diagonal cracks at mid-depth within the sheat span. Strengthened specimens grow to be more ductile after the redistribution of internal force on the CFRP Grids. The failure mode and variations of strains in the specimens are dependent on the shear span-to-depth ratio. The lower the shear span-to-depth ratio, the bigger failure load and the less variations in strain are observed. Additional anchorage of CFRP Grids does not only cause the improvement in the internal resistance, but also control the brittle shear failure of specimen after reaching the maximum loads.

• Journal of the Korean Statistical Society
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• v.23 no.2
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• pp.349-365
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• 1994

We develop in this paper the likelihood ratio test (LRT) for testing $H_1 : F_1 \preceq F_2$ against $H_2 - H_1$ where $H_2$ imposes no restriction on $F_1$ and $F_2$ and '$\preceq$' means failure rate ordering. Both one and two-sample problems will be considered. In the one-sample case, one of the two distributions is known, while we assume in the other case both are unknown. We derive the asymptotic null distribution of the LRT statistic which will be of chi-bar-square type. The main issue here is to determine the least favorable distribution which is stochastically largest within the class of null distributions.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.199-204
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• 1998

To analysis the failure character of Low-Heat concrete which is used to prevent the thermal crack caused by hydration heat, static loading test was performed by this test method, "Determination of the Fracture Energy of Motar and Concrete by Means of Three-Point Band Tests on Notched Beam" (suggested by RILEM 50-FMC Committe). This study compared and analysised the fracture energy of Mode I (opening mode), the most general pattern in the view of water-cemente ratio(W/C), compressive strength and age of Ordinary Portland Concrete and Low-Heat Concrete under the same mixture. The test results show that the case of Ordinary Portland Concrete and Low-Heat Concrete, low Water-Cemente ratio(W/C) cause the increase of fracture energy, and high failure-strength decrease failure-deflection, and the fracture energy of Low-Heat Concrete is similar to Ordinary Portland Concrete as the age increase. increase.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.353-360
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• 2005

When the weight if a concrete member makes problems, or when the cost of the concrete is relatively high, it may be economical to use a hollow concrete member. But a hollow R.C Pier may have poor ductility because of the brittle failure at the inner face of the hollow R.C Pier. This brittle failure results from the absence of the confinement at the inner face of the hollow R.C Pier. To avoid this brittle failure an internally confined hollow R.C Pier was developed. Test results show that the energy ductility ratio of a internally confined hollow R.C Pier have a superior energy ductility ratio to a general hollow R.C Pier.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.712-717
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• 2005

When the weight if a concrete member makes problems, or when the cost of the concrete is relatively high, it may be economical to use a hollow concrete member. But a hollow R.C column may have poor ductility because of the brittle failure at the inner face of the hollow R.C column. This brittle failure results from the absence of the confinement at the inner face of the hollow R.C column. To avoid this brittle failure an internally confined hollow R.C column by a steel tube was developed before. In this study, a hollow R.C column is internally confined by a corrugated steel tube instead of a general flat steel tube. And a column ductility is performed. Test results show that the energy ductility ratio of a internally confined hollow R.C column by a by a corrugated steel tube corresponds to $80\%$ of the energy ductility ratio of a general solid R.C column.

• Journal of Power System Engineering
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• v.18 no.1
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• pp.76-83
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• 2014

This study was carried out an experimental and finite element analysis on the fracture behavior of straight pipes with local wall thinning under internal pressure. Local wall thinning was machined on the pipes in order to simulate erosion/corrosion metal loss. The configurations of the eroded area has an eroded ratio of d/t=0.80~0.92 and an eroded length of l=25, 50 and 102 mm. Three-dimensional elastic-plastic analyses were also carried out using the finite element method, which is able to accurately simulate failure behaviors. In regards to the relation ship between pressure and eroded ratio, the criterion that can be used safely under operating pressure and design pressure were obtained from this calculation. The results of this calculation were in relatively good agreement with that of the experiment.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.769-774
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• 2000

The purpose of this study was to investigate the structural performance of reinforcement corrosion reinforced concrete beams strengthened with epoxy mortar system. Main test parameters are existence and the magnitude of the reinforcement corrosion and the reinforcing bar and the tensile reinforcement ratio of the specimens. eight beam specimens were tested to investigate the effectiveness of each test variables on maximum load capacity and failure mode. Test results showed that the ultimate moment of th specimens were higher tan the nominal moment and the flexural stiffness was increased about 2.5 times and the cracking moments occurred over 60% of the failure moment in comparison with same sized control beam. However, note that epoxy mortar may conduct member into brittle failure mode.