• Computers and Concrete
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• v.15 no.2
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• pp.259-277
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• 2015

The lack of experimental studies on the mechanical behavior of reinforced concrete (RC) haunched beams leads to difficulties in statistical and reliability analyses. This study performs stochastic and reliability analyses of the ultimate shear capacity of RC haunched beams based on nonlinear finite element analysis. The main aim of this study is to investigate the influence of uncertainty in material properties and geometry parameters on the mechanical performance and shear capacity of RC haunched beams. Firstly, 65 experimentally tested RC haunched beams and prismatic beams are analyzed via deterministic nonlinear finite element method by a special program (ATENA) to verify the efficiency of utilized numerical models, the shear capacity and the crack pattern. The accuracy of nonlinear finite element analyses is verified by comparing the results of nonlinear finite element and experiments and both results are found to be in a good agreement. Afterwards, stochastic analyses are performed for each beam where the RC material properties and geometry parameters are assigned to take probabilistic values using an advanced simulating procedure. As a result of stochastic analysis, statistical parameters are determined. The statistical parameters are obtained for resistance bias factor and the coefficient of variation which were found to be equal to 1.053 and 0.137 respectively. Finally, reliability analyses are accomplished using the limit state functions of ACI-318 and ASCE-7 depending on the calculated statistical parameters. The results show that the RC haunched beams have higher sensitivity and riskiness than the RC prismatic beams.

• Korea journal of population studies
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• v.14 no.1
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• pp.26-34
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• 1991

Migration studies that assume that decision making is done on an individual basis is overlooking the importance of the family factor. Considering that must people belong to families, it is more appropriate to view migration decision from the perspective of the family. This study analyzes the household migration decision whereby the alternatives are to stay, 10 undertake family migration or to undertake single migration of a member. In developing a conceptual model of household migration decision, it is assumed that the household's objective is to maximize household income which is a function of individual members' earnings. The benefits and costs of household migration and individual migration are identified and the household chooses the migration strategy that maximizes expected household income. When household members have conflicting earning prospects in the potential destination, the household considers single migration of the member with the best earning potentials. However, lone migration by a household member involves cost of family separation which is both monetary and psychic, and this study shows that lone migration is undertaken only when its net gains to the family are greater than the separation cost of the family. The major benefit of choosing single migration is the retention of home base in the place of origin which can serve as an insurance against the uncertainty of obtaining a job in the destination, the benefit that is unavailable in family migration. The conceptual analysis shows how a household's migration decision would depend on its members' economic roles and prospects in the destination. Besides the economic variables, social and life cycle variables of the family translate into separation costs and benefits of migration. This study indicates that one - earner family in low economic status but with good earning prospects and high separation costs is more likely to choose family migration over single migration.

• Journal of the Korean Society for Railway
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• v.19 no.1
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• pp.67-76
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• 2016

The asphalt-concrete trackbed system has many advantages in terms of maintenance and economics. However, methods to investigate practical use corresponding to the development of the trackbed system must be developed. The primary objective of this study was to evaluate the dynamic performance of the asphalt system in accordance with both the elastic and viscoelastic material characteristics and design thickness of the asphalt trackbed. More specifically, in order to reduce the uncertainty error of the Finite Element(FE) model, a three-dimensional full scale FE model was developed and then the infinite foundation model was considered. Finally, to compare the condition of viscoelastic materials, performance evaluation of the asphalt-concrete trackbed system was used to deal with the dynamic amplification factors; numerical results using isotropic-elastic materials in the FE analysis are presented.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.47
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• pp.299-318
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• 2010

International trade environment is rapidly changing. Developing all economic activities included in the value chain of economy out of a particular country or region in the trends where globalization is spreading all over the world, 'a borderless world' has been created and become common throughout the world. Especially, in case of East Asian region, becoming the factory of the world, China has become a center of the world's economic activities in recent years; and the increase of regional investment among East Asian countries and trade expansion focused on China has been the factor of promoting the formulation of a regional trade network. SCM is an efficient way of adaptation to the complexity or uncertainty on the scene through the achievement of a sustainable competitive advantage by integrating the activities of improving the relationships in the supply chain. In this study, Sumitronics, a Japanese company, was studied as a case of the company who had implemented SCM effectively and efficiently utilizing the East Asian trade network. Not being engaged in the manufacturing processes in the headquarter, Sumitronics has implemented SCM which is capable of maximizing the responsiveness upon the requirements of customers by effective information sharing. In particular, the profits of the company have been maximized through SCM by its headquarter in Japan, which is capable of managing each base in East Asia as China and Southeast Asia, etc. Korean companies may also be able to create a new source of profit by dint of establishing SCM as such. The results of this case study has revealed that the implementation of an effective business model is the key of the successful implementation of SCM.

• Journal of Korea Technology Innovation Society
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• v.21 no.2
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• pp.818-837
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• 2018

Technological innovation has inherent difficulties, largely due to the uncertainties of technology. Thus, the forecasting methodology to reduce the risk of uncertainty in the innovation process has been presented both in quantitative and qualitative fields. On the other hand, big data and artificial intelligence have attracted great interest recently, and deep learning, which is one of the algorithms of AlphaGo, is showing excellent performance. In this study, deep learning methodology was applied to the prediction of innovation performance. To make the prediction model, we used KIS 2016 data. The input factors were importance of information source and innovation objectives and the output factor was innovation performance index, which was calculated for this study. As a result of the analysis, it can be confirmed that the accuracy of prediction is improved compared with the previous studies. As learning progressed, the degree of freedom of prediction also improved.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.3
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• pp.216-227
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• 2020

The purpose of this paper is to identify a relative importance and priority of the factors of Competencies of project team member. It aims to present the differential competency factors from a differentiated perspective by applying the Leadership Development Questionnaire, which is the competency dimension required for manager, to team member. (1) Background: The diverse needs of customers and companies, and the uncertainty, complexity, ambiguity, and volatility of the environment surrounding the company in the era of the Fourth Industrial Revolution threaten the survival of company. In this respect, companies should implement the project management approach and strive to increase the capabilities of each team member. (2) Methods: AHP method was used to prioritize which factors were considered more importance level and the gap of relative importance level between project manager group and team members group. (3) Results: In the analysis of the relative importance of the upper class, weights were derived in the order of managerial competence, intellectual competence, and emotional competence. The sub-factor that respondents prioritize was communication as the 1st priority, and it was analyzed in the order of strategic perspective, achieving, critical analysis and judgement, and vision and imagination. There were some differences in the ranking of the relative importance of achieving and vision and imagination attributes between the PM group and TM group, it was analyzed that there was no significant difference overall. (4) Implications: The results of this study confirmed the recognition that team members are required to have the same competencies as the project manager. And based on the priorities of the competencies required of team members, companies are expected to cultivate professional and competent team members, and expand the roles and authority of team members so that they can actively carry out projects.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.47-54
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• 2013

This paper introduces a W-band millimeter-wave power standard transfer system using the direct comparison method. The transfer system was developed to evaluate the effective efficiency and calibration factor of a W-band waveguide power sensor. The evaluation method and the measured results of the directional coupler that characterizes the calibration system are studied. The uncertainties of the standard transfer system are investigated, and the major uncertainty contributors are discussed as well. The performance of the realized W-band power standard transfer system was verified by comparing results with reference values.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.9
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• pp.335-340
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• 2014

Crowd Sourcing-based Social App Manufacturing environment, a small app development project by a team of anonymous virtual performed without the constraints of time and space, and manage it for the app development process need to be automated method. Virtual teams with anonymity is a feature of the Social App Manufacturing, is an important factor that increases the uncertainty of whether the completion of the project or reduction in visibility of the progress of the project. In this study, as one of how to manage the project of Social App Manufacturing environment, the impact of risk that can be used to quantitatively measure the impact of the risk of delay in development has on the project also proposes a measurement model. Effects of risk and type of the impact of risks associated with delays in the work schedule also define the characteristic function, measurement model that has been proposed, suggest the degree of influence measurement equation of risk of the project in accordance with the progressive. The advantage of this model, the project manager is able to ensure the visibility of the progress of the project. In addition, identify the project risk of work delays, and to take precautions.

• Journal of Construction Engineering and Project Management
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• v.10 no.1
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• pp.16-32
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• 2020

Cost and time control of projects is important in preventing project failure. However, achieving effective cost and time control in practice is often challenging. The challenges of project cost and time control in practice are investigated by carrying out a questionnaire survey on the top 150 construction contractors in the UK followed by in-depth semi-structured interviews of practitioners from 15 construction companies in the country. Quantitative analysis reveals that design change is the most important factor inhibiting the ability of UK contractors from effectively controlling both the cost and time of construction projects. Four of the top five factors inhibiting effective cost control are also the top factors inhibiting effective time control albeit in a different order. These top factors-design changes, inaccurate evaluation of project time/duration, risk and uncertainty, non-performance of subcontractors and nominated suppliers were also found to be endogenous factors to the project. Additionally, qualitative analysis of the interviews reveals 16 key challenges to prevent for effective project cost and time control in practice. These are classified into four categorised based on where they stem from as follows; from the organisation (1. Lack of integration of cost and time during project control, 2. lack of management buy-in, 3. complicated project control systems and processes, 4. lack of a project control training regime); from the construction management/project management approach (5. Lapses in integration of interfaces, 6. project control not being implemented from the early stages of a project, 7. inefficient utilisation and control of labour, 8. limited time devoted to planning how a project will be controlled at the outset); from the client; (9. Excessive authorisation gates, 10. use of adversarial and non-collaborative forms of contracts, 11. communication problems within client set-up, 12. obstructive client representatives) and; from the project team (13. Lack of detailed/complete design, 14. lack of trust among the project partners, 15. limited time devoted to project control on site, 16. non-factual reporting). The study posits that knowledge of these project control inhibiting factors and challenges is the first step at ensuring they are avoided and enable the implementation of a more effective project cost and time control process in practice.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.4
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• pp.383-389
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• 2011

In this paper, a statistical calibration method is proposed in order to identify the variability of complex modulus for a rubber material due to operational temperature and experimental/model errors. To describe temperature- and frequency-dependent material properties, a fractional derivative model and a shift factor relationship are used. A likelihood function is defined as a product of the probability density functions where experimental values lie on the model. The variation of the fractional derivative model parameters is obtained by maximizing the likelihood function. Using the proposed method, the variability of a synthetic rubber material is estimated and applied to a rubber mount problem. The dynamic characteristics of the rubber mount are calculated using a finite element model of which material properties are sampled from Monte Carlo simulation. The calculated dynamic stiffnesses show very large variation.