• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2153-2162
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• 2011

The goal of this Paper is to reduce rail's wear in curved track by applying an additional surface layer material(High hardness and High resistance capacity of wear) on the top of the railhead. In order to evaluate appropriation of a coating material, experimental tests such as the varieties of fundamental properties tests (hardening, wear, tensile, and bending) and RCF(rolling contact fatigue)test were performed to establish fatigue wear and damage mechanism. As a result, wear performance of coating rail is better than heated rail about 6times and normal rail about 8~9times.

• Structural Engineering and Mechanics
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• v.30 no.6
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• pp.665-678
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• 2008

The beams components subjected to the loading such as axial, bending and cyclic thermal loads were studied in this research. The used constitutive equations are those of elasto-plasticity coupled to ductile and/or creep damage. The nonlinear kinematic hardening behavior was considered in elastoplasticity modeling. The unified damage law proposed for ductile failure and fatigue by the author of Sermage et al. (2000) and Kachanov's creep damage model applied to cyclic creep and low cycle fatigue of beams. Based on the results of the analysis, the shakedown limit loads were determined through the calculation of the residual strains developed in the beam analysis. The iterative technique determines the shakedown limit load in an iterative manner by performing a series of full coupled elastic-plastic and continuum damage cyclic loading modeling. The maximum load carrying capacity of the beam can withstand, were determined and imposed on the Bree's interaction diagram. Comparison between the shakedown diagrams generated by or without creep and/or ductile damage for the loading patterns was presented.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.637-640
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• 2002

The deterioration of RC deck slabs has been a serious problem and high portion of budget has been a spent for repair and strengthening of deck slab. The concrete deck slabs are subject to direct application of vehicle loading and accumulation of fatigue damage. Besides, various environmental causes. In this paper, an probabilistic study is carried out to predict exact load effects and structural capacity of deck slab during its service life, and estimate an appropriate remaining life of deck slab. To achieve this purpose the live load model is developed using by influence line including deterioration of deck slab, and deterioration model of bridge deck slab is developed. In addition, the fatigue life of reinforced concrete deck slabs considering corrosion of reinforcement are estimated based on experimental formula. This study will help rational decisions for the management and repair of reinforced concrete deck slabs.

• Magazine of the Korea Concrete Institute
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• v.3 no.1
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• pp.87-94
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• 1991

Many different damage models have been prolxlsed for concrete in the past. Most of these are not well suited to predict the residual strength of damaged RC members. This paper reviews some basic facts alxlut concrete damage and uses these to systematically model damage as a low-cycle fatigue phenomenon. Instead of the number of load cycles to failure the energy dissipation capacity of a member is taken as the main variable, which depends on many different factors. The model is capable of simulating reasonably well the strength and stiffness degradation of I{C members subjected to strong cyclic loads.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.22-26
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• 2002

The goal of this study is to replace the current forward 2-piece propeller shaft of 8 ton large truck made of steel with 1-piece composite propeller shaft. A low cost Glass/Epoxy composite propeller shafts were successfully developed, which satisfy requirements such as the capacity of static torque transfer, fatigue strength and bending natural frequency. Devising secure joining method of a composite tube and metal yoke was the most critical issue in successful development of a high torque composite propeller shaft. In this study, joining method using thermal interference fit was adopted for composite to metal joint. Optimum conditions of heating temperature and interference level of thermal interference fit were determined from thermal stress analysis using 3D finite element method. Static torsion test, fatigue test, RPM and balance test were performed to verify the design.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.59-64
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• 2001

The concrete bridge decks are in need of replacement and rehabilitation due to decreasing load carrying capacity. In this study, to extend life cycle of the concrete bridge decks which are reinforced with the glass fiber sheets, the concrete bridge decks are examined on the strengthen effect and the fatigue behavior. The behavior of strengthened slabs is represented by load-displacement relationship, variation of compliance and total released energy. Owing to result of that, the strengthened slabs is modified the elasticity, the compliance and represents to control the crack elongation, to elevate the total released energy, to modify the fatigue life. When the concrete bridge deck is strengthened, the crack propagation nay be controled efficiently.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.851-856
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• 1998

In recent years, glassfibers have been used for strengthening in RC structure because of low material cost and easy repairing work. The purpose of this study is to experimentally and analytically investigate the effect of glassfibers for enhancing the capacity of RC structure. The result shows that yield and ultimate strength of RC beam with glassfibers are increased by approximate 13% and 26%, comparing with those for RC beam without glassfibers. It has been observed from the test that fatigue behaviors of RC beam with glassfibers have been significantly and large improved comparing with those for RC beam without glassfibers.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.357-364
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• 2003

In the conventional reinforced-concrete bridge deck, concrete and steels are likely to be deteriorated and corroded under the influence of noxious environment. To cope with these problems caused in the conventional reinforced-concrete bridge deck, pultruded composite bridge deck having light weight, high strength, corrosion resistance and durability is developed. For the DB24 truck load pultruded composite bridge deck is designed and fabricated. For the fabricated and assembled deck panel, structural testing such as flexural test, local fatigue test, flexural fatigue test are conducted to verify the deck capacity experimentally. In this paper design for deck profile, details of connection and experimental results of composite bridge deck are presented.

• Nuclear Engineering and Technology
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• v.34 no.2
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• pp.176-185
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• 2002

A 4-bundle shift refuelling method of CANDU6 F/H (Fuel Handling) System is analyzed to assess the operational flexibility and capacity of F/H system. The current 8-bundle shift refuelling scheme requires to refuel eight fuel bundles from a single fuel channel, and to refuel 14 fuel channels in a week on average assuming that the reactor is in a steady state. The analysis showed that the 4-bundle shift refuelling method increases F/M (Fuelling Machine) duty cycle and operator load. However, the fuellin’g method change from the 8- to 4-bundle shift refuelling ill not require additional team of operators. A marginal increase in the maintenance cost may be resulted in by the change of fuelling method and the increase of fatigue usage factors requires some components to be replaced during the FM lifetime.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.49-57
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• 2002

As composite materials, the addition of steel fiber with concrete significant)y improves the engineering properties of structural members, notably shear strength and ductility. Flexural strength, fatigue strength, and the capacity to resist cracking are also enhanced. Especially the strengthening effect of steel fiber in shear is to prevent the brittle shear failure. In this study, shear-strengthening effect of steel fiber in RC short columns were investigated from the literature surveys and 10th specimem's member test results. From the test results, following conclusions can be made; the maximum enhancement of shear-strengthening effect can be achieved at about 1.5 ％ of steel fiber contents, shear strength and ductility capacity were improved remarkably in comparison to stiffness and energy dissipation capacity in steel fiber reinforced concrete.