• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.2
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• pp.164-176
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• 1996

The main intention of this paper is to develop and compare the algorithm based on finite element procedures for nonlinear transient dynamic analysis which has combined effects of material and geometric nonlinearities. Incremental equilibrium equations based on the principle of virtual work are derived by the finite element approach. For the elasto - plastic large deformation analysis of shells and the determination of the displacement-time configuration under time-varying loads, the explicit, implicit and combined explicit-implicit time integration algorithm is adopted. In the time structure is selected and the results are compared with each others. Isoparametric 8-noded quadrilateral curved elements are used for shell structure in the analysis and for geometrically nonlinear elastic behaviour, a total Lagrangian coordinate system was adopted. On the other hands, material nonlinearity is based on elasto-plastic models with Von-Mises yield criteria. Thus, the combined explicit-implicit time integration algorithm is benefit in general case of shell structure, which is the result of this paper.

• Steel and Composite Structures
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• v.13 no.6
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• pp.561-570
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• 2012

Seismic collapse analysis requires efficient and automated method to perform thousands of time history analyses. The paper introduced the advantages of speed and convergence property of explicit method, provided a few techniques to accelerate speed of calculation and developed an automated procedure for collapse assessment, which combines the strong capacity of commercial explicit finite element software and the flexible, intelligent specialties of control program written in FORTRAN language aiming at collapse analysis, so that tedious and heavy work of collapse analysis based on FEMAP695 can be easily implemented and resource of calculation can be made the best use of. All the key commands of control program are provided to help analyzers and engineers to cope with collapse assessment conveniently.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.13 no.4
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• pp.257-265
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• 2009

In this paper we find an explicit form of upper bound of Hausdorff distance between given cubic spline curve and its quadratic spline approximation. As an application the approximation of offset curve of cubic spline curve is presented using our explicit error analysis. The offset curve of quadratic spline curve is exact rational spline curve of degree six, which is also an approximation of the offset curve of cubic spline curve.

• Journal of The Korean Association For Science Education
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• v.31 no.4
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• pp.641-662
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• 2011

In this study, explicit Teaching and Learning strategy for middle school students were developed to improve basic science process skills. After applying these strategy in an actual class, the effects of Teaching and Learning strategy and change of students were analyzed. Explicit Teaching and Learning strategy to improve basic science process skills are developed based on analyzing preceding research. The use of application criteria for class of basic science process skills combined with explicit Teaching and Learning strategy, it is sought for the explicit instructional procedures of said skills. After analyzing the class in which explicit Teaching and Learning strategy were demonstrated, students reported that they were able to comprehend basic science process skills more effectively through the stages of explicit explaining and independent practice. The showing demonstration stage was heavily emphasized by the teacher in this class. Analysis of students' understanding degree about basic science process skills, most of them show positive outcome. Another analysis of ripple effect on daily life and other subjects, it is found that students could have the attitude to make use of science process skills for themselves. Through the result of study, it is found that explicit Teaching and Learning strategy that are developed from this study are an effective way to comprehension students' basic science process skills. Thus, continued study is needed to develop and spread explicit Teaching and Learning strategy of science process skills to be applicable in actual classes in secondary schools.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.245-248
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• 1999

Explicit dynamic finite element analysis has been used widely in the field of sheet metal forming. However in using the analysis technique there are some parameters which are not clearly defined so that engineers may obtain inaccurate solutions In the present study parameters such as time step damping ratio penalty constant and punch speed were investigated on their influence to the solution behavior. Considered forming processes are plane stain bending by a punch and axisymmetric deep drawing.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.136-140
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• 2000

It is desirable to predict springback quantitatively and accurately for the tool and process design in sheet stamping operations, however, it is blown very difficult. The result of springback analysis by the finite element method is sensitively influenced by numerical factors such as blank element size, number of integration point, punch velocity, contact algorithm etc. In the present work, a parametric study by Taguchi method is performed in order to evaluate the influence of numerical factors on springback Quantitatively and to obtain the combination of numerical factors which yields the best approximation to experimental data. Since springback is determined by the residual stress after forming process, it is important to evaluate stress distribution accurately. The oscillation in the time history curve of stress obtained by explicit FEM says that the stress solution at termination time is in very unstable state. Therefore, a variability study is also carried out in this study in order to assess the stability of implicit springback analysis starting from the stress solution by explicit forming simulation. The 2D draw bending process, one of the NUMISHEET '93 benchmark problems, is adopted as an application model.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.163-170
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• 2000

The distinct element method has been effectively applied to the analysis of stability and behavior of jointed rock masses. In this paper the modelling characteristics of different types of distinct element model were investigated. Arch tunnel examples were chosen to compare the calculation results of two computer codes, NURBM and CBLOCK, where the former is based on implicit algorithm, and the other on explicit one. CBLOCK calculations show that joint properties are very important parameters in the stability analysis and that the joint stiffness ratio associated with joint configuration could be used as an indicator, whereas NURBM differ from that. Some other disagreements were also identified.

• Tunnel and Underground Space
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• v.10 no.3
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• pp.410-417
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• 2000

The distinct element method has been effectively applied to the analysis of stability and behavior of jointed rock masses. In this paper the modelling characteristics of different types of distinct element model were investigated. Arch tunnel examples were chosen to compare the calculation results of two computer codes, NURBM and CBLOCK, where the former is based on implicit algorithm, and the other on explicit one. CBLOCK calculations show that joint properties are very important parameters in the stability analysis and that the joint stiffness ratio associated with joint configuration could be used as an indicator, whereas NURBM differ from that. Some other disagreements were also identified.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.349-359
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• 2001

An enhanced four-node plate element, which has been developed for explicit dynamic analysis of plate, is described in this paper. Reissner-Mind1in(RM) assumptions are adopted to consider transverse shear deformation effects in the present plate element. RM plate element produces a shear locking phenomena in thin plate so that the substitute natural strains based on assumed strain method are explicitly derived. The present plate element is applied into the explicit transient algorithm and the mass matrix of plate is formulated by using special lumping method proposed by Hinton et al. The performance of the element is verified with numerical examples.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1570-1594
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• 2017

Social network services have recently changed from environments for simply building connections among users to open platforms for generating and sharing various forms of information. Existing user reputation computation methods are inadequate for determining the trust in users on social media where explicit ratings are rare, because they determine the trust in users based on user profile, explicit relations, and explicit ratings. To solve this limitation of previous research, we propose a user reputation computation method suitable for the social media environment by incorporating implicit as well as explicit ratings. Reliable user reputation is estimated by identifying malicious information raters, modifying explicit ratings, and applying them to user reputation scores. The proposed method incorporates implicit ratings into user reputation estimation by differentiating positive and negative implicit ratings. Moreover, the method generates user reputation scores for individual categories to determine a given user's expertise, and incorporates the number of users who participated in rating to determine a given user's influence. This allows reputation scores to be generated also for users who have received no explicit ratings, and, thereby, is more suitable for social media. In addition, based on the user reputation scores, malicious information providers can be identified.