• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.47-53
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• 2014

The paper investigates the limit state of deflection for short and medium span steel girder bridges. Deflection depends on stiffness of steel girders and integrity of the reinforced concrete slab (composite action). Load and resistance parameters are treated as random variables. A probabilistic model is developed for prediction of the deflection. The structural performance can be affected by deterioration of components, in particular corrosion of steel girders. In addition, the creep of concrete can greatly influence the deflection of composite structures. Therefore, the statistical models for creep and corrosion of structural steel are incorporated in the model. Structures designed according to the AASHTO LRFD Code are considered. Load and resistance models are developed to account for time-variability of the parameters. Monte Carlo simulations are used to estimate the deflections and probabilities of serviceability failure. Different span lengths and girder spacing are considered for structures designed as moment-controlled and deflection-controlled. A summary of obtained results is presented.

• Journal of Applied Reliability
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• v.10 no.4
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• pp.237-250
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• 2010

Railway safety aims to ensure that railways take appropriate action to limit the risk of injury to persons or damage to property, to acceptable levels. Accreditation system specifies railway safety requirements to be included in a railway safety management system by any organization seeking to demonstrate the ability to control the processes that determine the acceptability of railway safety activities. The objective of this research is to investigate the international accreditation system for railway safety management. The yield information is quite valuable to operate collaborative processes with all interfacing transport operators and undertakings to facilitate risk control across the railway system.

• Steel and Composite Structures
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• v.15 no.4
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• pp.425-438
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• 2013

A new-styrofoam-concrete composite sandwich slab with function of heat insulation is designed. Four full-scale simply supported composite sandwich slabs with different shear connectors are tested. Parameters under study are the thickness of the concrete, the height of profiled steel sheeting, the influence of shear connectors including the steel bars and self-drilling screws. Experimental results showing that four specimens mainly failed in bending failure mode; the shear connectors can limit the longitudinal slippery between the steel profiled sheeting and the concrete effectively and thus guarantee the good composite action and cooperative behavior of two materials. The ultimate sagging bending resistance can be determined based on plastic theory. This new composite sandwich slab has high sagging bending resistance and good ductility. Additionally, these test results help the design and application of this new type of composite sandwich slab.

• Proceedings of KOSOMES biannual meeting
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• 2003.05a
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• pp.153-158
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• 2003

Design of general steel structure had applied and achieve elastic design concept mainly so far. Because elastic design supposes that whole structure complies with elasticity formula as that achieve via allowable stress of material is concept that calculate stress distribution of construction about action external load and estimate load of when the maximum stress reaches equally with allowable stress that is established beforehand by maximum safety load of the structure. But, absence that compose actuality structure by deal with external load increase small success surrender and structure hardness falls and tell structure in limit state finally on the whole as showing complicated conduct by interference between these breakdown at buckling by compression. Examined closely about conduct of place since initial buckling through carbon vocal cords transformation finite element analysis series (ANSYS) that place mending condition supposes case that is boundary condition in this investigation.

• International Journal of Control, Automation, and Systems
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• v.3 no.spc2
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• pp.302-307
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• 2005

A novel neuro controller based simple neuro-structure with modified error function is introduced in this paper. This controller consists of two independent controllers, known as the voltage regulator and the angular controller. The voltage regulator is used to modify terminal voltage for the purpose of tracking a reference voltage. The angular controller is utilized to guarantee the stability of the system. In this structure each neuron uses a linear hard limit activation function that depends on the controlled variable and its derivatives. There is no need for parameter identification or any off-line training data. Two proposed controllers are merged by a smooth switch to build a complete controller. The effectiveness of the proposed novel control action is demonstrated through some computer simulations on a Single-Machine Infinite-Bus (SMIB) power system.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.2
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• pp.40-52
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• 2000

The aim of this study was to evaluate the prevailing ergonomic conditions regarding low back injury in an assembly factory, In this study, analytic biomechanical model and NIOSH guidelines were applied to evaluate risk levels of low back injury for automobile assembly jobs. Total of 246 workers were analysed. There were 10 jobs with greater back compressive forces than 350kg at L5/S1. Also there were 44 jobs over Action Limit in terms of 1981 NIOSH guidelines. This could in part be explained by the ergonomic conditions of the companys analysed as not hazardous, with a relatively low duration of 'combined' extreme work posture. However, more ergonomic intervention could be done based on those results.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.45-52
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• 2003

A finite element procedure to estimate ultimate strength of space frames considering spread of plasticity is presented. The improved displacement field is introduced based on inclusion of second order terms of finite rotations. All the nonlinear terms due to bending and torsional moment as well as axial force are precisely considered. The concept of plastic hinge is introduced and the incremental load/displacement method is applied for the elasto-plastic analysis. The initial yield surface is defined based on the residual stress and the full plastification surface is considered under the combined action of axial force, bending and torsional moments. The elasto-plastic stiffness matrices are derived using the flow rule and the normality condition of the limit function. Finite element solutions for ultimate strength of space frames are compared with available solutions and experimental results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.3
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• pp.169-176
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• 2000

In the strengthening of the existed reinforced concrete(RC) structures, it is required that the more rational strengthening method and the amounts of strengthening materials would be decided under the consideration of the present state of RC structures. Therefore, this study examined the strengthening effects of concrete cylinders strengthened with carbon fiber sheet(CFS). In this studying we modeled the reduction of internal forces and the initial strains of concrete cylinders as the load history over the elastic limit. From the results, it revealed that the strengthening of two layer CFS was more effective on the concrete cylinders under the action of load history such as cyclic and cracking load.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.4
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• pp.133-139
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• 2011

In this paper, we propose a hybrid filter for noise reduction. The proposed method adjusts rational filtering direction according to an edge in the image using median filtered data. Rational filter modulates the coefficients of a linear lowpass filter to limit its action in presence of image details. By the ratio of polynomials in the input variables, rational filter reduces noise adaptively. Median filter is widely used to reduce impulse noise, but removes some details for highly corrupted images. Also, desirable details are removed when the window size is large. Our proposed algorithm combines rational filter and median filter. Thus, proposed method not only preserves edge, but also reduces noise in uniform region. Experimental results show that our proposed method has better quality than those by existing median and rational filtering methods.

• Journal of the Ergonomics Society of Korea
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• v.11 no.2
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• pp.3-13
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• 1992

Resultant compressions on the L5/S1 joint of six subjects were studied as they lif- ted light weights in sitting and standing work postures. The subjects activities were photographed and analysed later by a static biomechamical computer model. Statistically significant differences were found between the result of the two postures analyses. Sitting posture showed significantly high compressions on the joint when doing several material handling tasks having the same work loads from the hip joint. Therefore, it is recommended that working with light weights in standing is less hazardous than doint the same work sitting postures, although both the maximum compression forces are under the Action Limit suggested by NIOSH.