• Journal of the Society of Naval Architects of Korea
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• v.45 no.1
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• pp.81-86
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• 2008

Recently, a mesh-size insensitive structural stress definition that provides a stress state at weld toe with relatively larger mesh size compared to conventional approaches has been proposed. The structural stress definition is based on the elementary structural mechanics theory and provides an effective measure of a stress state in front of weld toe. In this study, as an experimental validation of structural stress method in obtaining the fatigue strength of weldments, a series of fatigue test has carried out for longi-web connections, which are representative of ship-like structures. Based on the result from this study, it is expected to develop a more precise fatigue strength evaluation technique and to reduce time and cost associated with the fatigue design of ship and offshore structures.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.363-379
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• 2013

Dynamic displacement of structures is an important index for in-service structural condition and behavior assessment, but accurate measurement of structural displacement for large-scale civil structures such as long-span bridges still remains as a challenging task. In this paper, a vision-based dynamic displacement measurement system with the use of digital image processing technology is developed, which is featured by its distinctive characteristics in non-contact, long-distance, and high-precision structural displacement measurement. The hardware of this system is mainly composed of a high-resolution industrial CCD (charge-coupled-device) digital camera and an extended-range zoom lens. Through continuously tracing and identifying a target on the structure, the structural displacement is derived through cross-correlation analysis between the predefined pattern and the captured digital images with the aid of a pattern matching algorithm. To validate the developed system, MTS tests of sinusoidal motions under different vibration frequencies and amplitudes and shaking table tests with different excitations (the El-Centro earthquake wave and a sinusoidal motion) are carried out. Additionally, in-situ verification experiments are performed to measure the mid-span vertical displacement of the suspension Tsing Ma Bridge in the operational condition and the cable-stayed Stonecutters Bridge during loading tests. The obtained results show that the developed system exhibits an excellent capability in real-time measurement of structural displacement and can serve as a good complement to the traditional sensors.

• Journal of Technology Innovation
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• v.7 no.1
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• pp.14-35
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• 1999

This paper presents the relationship between the pace of structural change and the magnitude of employment growth in the manufacturing sector in OECD countries. To measure the pace of structural change, the compositional change index in value-added in manufacturing sector is introduced. For mid to long-term there seems to be a positive relationship between the pace of structural change and the magnitude of employment growth. In those countries with higher value of the compositional index, the employment growth in manufacturing sector was generally higher. To analyse the characteristics of structural change in manufacturing sector, this paper classifies manufacturing industries into groups: one based on technology, one on orientation, one on wages and one on skills. The international comparison of manufacturing sector's employment patterns based on above four classifications are presented. International comparison suggests that Korean manufacturing sector move into jobs with more skills and knowledge The structural change of SMEs and large firms are compared based on above four classification methods. It is shown that SMEs' employment in low value sectors, that is low-technology, labor-intensive, tow-wage, and unskilled sectors, have risen faster than SMEs' employment in high-technology, science-based, high-wage and skilled sectors. Large firms' employment have been mainly increased in high value sectors. However, the employment growth of both large and small firms have been concentrated on production worker-intensively-using sectors, i.e. unskilled sectors. This widened the wage differential of production workers by firm sizes and concurrently led to severe shortage of production workers for SMEs, which has little ability to pay high wage to production workers because they usually belong to low-wage sectors. Korea need to push SMEs forward to high value sectors. The premise of that is, however, to pull large firms out of production worker-intensively-using sectors.

• Journal of Technology Innovation
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• v.14 no.1
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• pp.177-199
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• 2006

Recently, it has become important to establish a technology appraisal system because of increasing a service of technology credit guarantee. Also, there have been many efforts to evaluate a technology in the advanced countries. The technology/credit appraisal model which can measure firms' performance was suggested by Small and Medium Business Administration. In this paper, we analyze a structural validity of the model by confirmatory factor analysis and estimate the model which can distinguish whether an investment is possible or not by discriminant analysis.

• Structural Engineering and Mechanics
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• v.22 no.3
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• pp.293-310
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• 2006

In seismic prone areas it is possible to meet very different objects (equipment components, on shelf artefacts, simple architectural elements) that can be modelled as a rigid body rocking on a rigid foundation. The interest in their behaviour can have different reasons: seismological, in order to estimate the ground motion intensity, or more strictly mechanical, in order to limit the response severity and to avoid overturning. The behaviour of many rigid bodies subjected to twenty wide ranging acceleration recordings is studied here. The response of the blocks is described using kinematic and energy parameters. A condition under which a so called scale effect is tangible is highlighted. The capacity of the signals to produce overturning is compared to different ground motion parameters, and a good correlation with the Peak Ground Velocity is unveiled.

• Computational Structural Engineering
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• v.5 no.1
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• pp.83-89
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• 1992

A practical method of estimating inelastic deflection of reinforced concrete slab under service load is presented. Based on the elastic results of linear finite element analysis and area of reinforcement, inelastic deflection multiplier(.betha.) is evaluated and desired deflection as a measure of serviceability of the designed slab is obtained. Example for the corner supported slab shows that the results from the proposed method agree well with those from the experiment/and nonlinear finite element analysis. Application of the method to the design of irregular slab is also considered.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.614-617
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• 2008

This paper presents the numerical investigation of the characteristics of biaxial flexure specimens for the Biaxial Flexure Test(BFT) which was recently developed to measure the biaxial tensile strength of concrete. Using FEM, the effect of size and eccentricity on the specimens was evaluated. The parameters such as radious of the support and the loadings, thickness and free length were studied. The results of the FE analysis were entirely consistent with the predictive solution, when b/agt;0.4, h/alt;0.6 and the thickness of the specimens were increased. On the other hands, when b/agt;0.4, those with lesser free length showed good results. To limit the difference between the stresses at the end points of 2b as the specimen was sustained and the stress at the center point of the specimen are not over 10%, lateral eccentricity was analyzed to be in the limits of 3%.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.429-434
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• 2008

The objective of this paper is to introduce a project on developing Finish Drawing Automation System. The system aims to improve efficiency of the BIM-based estimation, which is realized by automatic derivation of three-dimensional geometry models of the finish details. First, overall workload differences between the drawing-based estimation methods and the BIM-based methods are analyzed. Second, an automated finish detail design method is proposed as a time-saving measure for the BIM-based estimation, as manual modeling accounts for the most time spent in the model-based estimation process. Finally, the proposed system is evaluated using a case of washboard design.

• Journal of the Korean institute of surface engineering
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• v.50 no.3
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• pp.141-146
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• 2017

We investigated configuration of metallic and insulating domains in $VO_2$ thin films, while spanning metal-insulator phase transition. Kelvin probe force microscopy, of which spatial resolution is less than 100 nm, enables us to measure local work function (WF) at the sample surface. The WF of $VO_2$ thin films decreased (increased) as increasing (decreasing) the sample temperature, during the phase transition. The higher and lower WF regions corresponded to the insulating and metallic domains, respectively. The metallic fraction, estimated from the WF maps, well explained the temperature-dependent resistivity based on the percolation model. The WF mapping also showed us how the structural defects affected the phase transition behaviors.

• Structural Engineering and Mechanics
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• v.60 no.3
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• pp.413-431
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• 2016

A sensitivity analysis estimates the effect of the change in the uncertain variable parameter on the probability of the structural failure. A novel fuzzy random reliability sensitivity measure of the failure probability is proposed to consider the effect of the epistemic and aleatory uncertainties. The uncertainties of the engineering variables are modeled as fuzzy random variables. Fuzzy quantities are treated using the ${\lambda}$-cut approach. In fact, the fuzzy variables are transformed into the interval variables using the ${\lambda}$-cut approach. Genetic approach considers different possible combinations within the search domain (${\lambda}$-cut) and calculates the parameter sensitivities for each of the combinations.