• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.83-92
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• 2016

The purpose of this study is to evaluate the seismic performance of domestic unreinforced masonry(URM) buildings using nonlinear dynamic analysis. For that, the nonlinear hysteresis models suggested in the previous research were validated for the dynamic analysis. The results of the shaking table test were compared with the dynamic analysis results using the suggested nonlinear hysteresis models. As a result, the nonlinear hysteresis models were expected to be applicable to the dynamic analysis of URM buildings. Based on the models, the dynamic analysis of domestic URM buildings varying the number of stories and opening ratio was carried out. The analysis results showed that most of the domestic URM buildings were very vulnerable to design earthquake in Korea.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.35-44
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• 2015

Two main parameters were examined such as CSA content and polymer-binder ratio to find effects on the strength, water absorption, chloride ion penetration depth, carbonation depth, length change and chemical resistance of polymer-modified mortar with CSA and EVA polymer powder (EVAPP). As results, compressive, flexural, tensile, adhesive strengths, and length change of the polymer-modified mortar with CSA and EVAPP increases with increasing CSA content and polymer-binder ratio, although the water absorption, chloride ion penetration depth, and carbonation depth decrease with increasing polymer-binder ratio and CSA content, and also the chemical resistance decreases. Such strength and durability development is attributed to the high tensile strength of EVA polymer and the improved bond between cement hydrates and aggregates because of the addition of EVAPP and CSA.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.97-103
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• 2017

As the shortage of concrete aggregates is intensifying, the development of alternative resources is urgent. As the amount of steel slag increases year by year, attempts are being made to recycle slag into high-value-added products in order to develop an efficient resource recycling industry based on slag and to obtain economic benefits. However, the use of electric arc furnace oxidizing slag (EOS) as building materials is practically limited because it contains unstable materials. In this paper, physical properties of concrete were evaluated by using electric arc furnace slag aggregate. It has been produced with two levels of general strength area W / C 45% and high strength area W / C 30%. Fresh concrete has been tested in air content, flow and slump, unit weight. The properties of the cured concrete were investigated by compressive strength, bending strength and unit volume weight. As a result of this study, strength of concrete increased with increasing EOS aggregate mixture.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.124-131
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• 2017

The purpose of this study is to evaluate the basic performance of cement mortar for repair using alumina cement and nitrite can be cured in low temperature environment. For this purpose, the repair mortar used in the domestic construction site was selected and the experimental evaluation was carried out by adjusting the mixing amount by substituting alumina cement and nitrite for the blending ratio. The experimental test results confirmed that alumina cement and nitrite were replaced with the repair mortar, the initial strength was improved. Also, the chemical resistance was improved, the shrinkage behavior was decreased, and the resistance to freezing and thawing was increased. As a result, applying alumina cement and nitrite at a ratio of 2:1 at 7.5%, the surface condition was maintained for 5 months or longer and it was judged to be excellent in practical use for external structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.97-102
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• 2018

Conventional PSC I type girders were adversely affected by the self - weight of concrete, anchorage, prestressing. In order to overcome this problem, PSC girder was constructed with a hollow in the web and developed a hollow web PSC type I girder which is applicable to 50 - 70m span by multistage stressing and then actually long span hollow web PSC girder bridge was constructed. In this study, the results of Static Load Test and the Finite Element Analysis of the hollow web PSC I girder bridges were compared and analyzed, and the Load Carrying Capacity and safety of PSC girder bridges were evaluated. The Static Load Test and the numerical analysis results of this bridge showed similar tendency and the behavior of the hollow web PSC I girder was well simulated. The entire girders of the bridges had sufficient Load Carrying Capacity under the live load design condition and the bridges satisfied the safety and confirmed the appropriateness of the construction.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.405-406
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• 2006

Recently, the flat display modules such as plasma or TFT-LCD employ thin crystallized panels which are normally weak to high level transient mechanical energy inputs. As a result, anti-shock performance is one of the most important design specifications for TFT-LCD modules. However, most of large display module designs are generated based on engineers own experiences. Also, a large-scale analysis to evaluate complex material and structural behaviors is one of interesting topic in diverse engineering and scientific fields. The utilization of massively parallel processors has also been a recent trend of high performance computing. The objective of this paper is to introduce a parallel process system which consists of general purpose finite element analysis solver as well as parallelized PC cluster. The parallel processing system is constructed using thirty-two processing elements and the finite element program is developed by adopting hierarchical domain decomposition method. In order to verify the efficiency of the established system, an impact analysis on thin and complex sub-parts of flat display modules is performed. The evaluation results showed a good agreement with the corresponding reference solutions, and thus, the parallel process system seems to be a useful tool fur the complex structural analysis such as IT related products.

• International Journal of Highway Engineering
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• v.5 no.1 s.15
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• pp.35-45
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• 2003

This paper presents a theoretical approach for estimation of CBR-value of subbase course and subgrade using a portable pavement dynamic cone penetrometer(PDCP). The PDCP used in this paper was based on a design from South Africa and extensive studies by Kleyn(1982) and more recently by Liveneh and Ishai(1987) and Chua(1988). To date, California Bearing Ratio[CBR] value was studied mainly for application of pavement structural design. This study was initiated to develop a method of obtaining the in situ CBR-values of subbase and subgrade for the structural evaluation of pavements in the swift and inexpensive manner. PDCP tests were implemented at 20 different kinds of soil samples in the lab and test results were analysed by a theoretical approach introduced. The procedure presented provides acceptable and promising results.

• International Journal of Highway Engineering
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• v.19 no.6
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• pp.13-21
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• 2017

PURPOSES : In this research, an SB3-level roadside barrier for a highway transition zone that meets the newly established guide Installation and Management Guide for Roadside Safety Appurtenance is developed. Its performance is evaluated by a numerical simulation and real-scale vehicle impact test. METHODS : The commercial explicit dynamic software LS-DYNA is utilized for impact simulation. An FE model of a passenger vehicle developed and released by the National Crash Analysis Center (NCAC) at George Washington University and a heavy goods vehicle (HGV) model developed by the TC226/CM-E Work Group are utilized for impact simulation. The original vehicle models were modified to reflect the conditions of test vehicles. The impact positions of the passenger vehicle and truck to the transition guardrail were set as 1/2 and 3/4 of the transition region, respectively, according to the guide. RESULTS : Based on the numerical simulation results of the existing transition barrier, a new structural system with improved performance was suggested. According to the result of a numerical simulation of the suggested structural system, two sets of transition barriers were manufactured and installed for real-scale vehicle impact tests. The tests were performed at a test field for roadside safety hardware of the Korea Highway Corporation Research Institute. CONCLUSIONS : The results of both the real-vehicle impact tests and numerical simulations of the developed transition barrier satisfied the performance criteria, and the results of numerical simulation showed good correlation with the test results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.121-128
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• 2012

In this paper, nonlinear analysis for reinforced concrete structure for power transmission line is performed by considering the characteristics of the failure, which are depend on loading conditions and concrete material models. On the numerical evaluation for the failure behavior, the finite element analysis is applied. For the concrete material model, microplane model based on concrete damage is introduced. However, to describe the crack bridging effect of long and short fiber of steel fiber reinforced concrete (SFRC), tensile softening model is suggested and applied for SFRC. An numerical results by finite element technique are compared with the experiment results for box culvert specimen. Comparing on the experimental and analytical results, validity and reliability of numerical analysis are investigated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.155-162
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• 2011

The structures that use the bridge plates are considered to have advantages such as short work term, excellent economical efficiency and low maintenance cost. Bridge plates are being widely used for water ducts and eco-corridors as replacements of reinforced concrete ducts. Bridge plates are deep and have greater pitch as compare to conventionally deep corrugated steel plate. They are expected to be increasingly used in the future. The structures that use bridge plates have two forms, such as arch type and box type. The arch type structures are designed based on the compressive strength, and the box type structures, based on the moment in the plate member. In this study, the ultimate strength and moment strength of the connection part of the specimens were examined by their thickness. Static and bending tests used to evaluate the performance of bridge plate. Finally, These results were used in the design process.