• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.496-500
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• 1997

This paper describes an automated system for analyzing the stress intensity factors(SIFs) of three-dimensional (3D) cracks. A geometry model, i.e.a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-noded quadratic tetrahedral solid elements are generated by the Delauuay triangulation techniques. The singular elements such that the mid-point nodes near crack fornt are shifted at the quarter-points are automatically placed along the 3D crack front. THe complete finite element (FE) model generated, i.e the mesh with material properties and boundary conditions is given to one of the commercial FE codes, and a stress analysis is performed. The SIFs are calculated using the displacement extrapolation method. To demonstrate practical performance of the present system, a semi- elliptical surface crack in a plate subjected to tension is solved.

• Journal of Educational Research in Mathematics
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• v.14 no.3
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• pp.239-266
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• 2004

This article presents new perspectives for analysing and diagnosing students' mathematical errors on the basis of Pascaul-Leone's neo-Piagetian theory. Although Pascaul-Leone's theory is a cognitive developmental theory, its psychological mechanism gives us new insights on mathematical errors. We analyze mathematical errors in the domain of proof problem solving comparing Pascaul-Leone's psychological mechanism with mathematical errors and diagnose misleading factors using Schoenfeld's levels of analysis and structure and fuzzy cognitive map(FCM). FCM can present with cause and effect among preconceptions or misconceptions that students have about prerequisite proof knowledge and problem solving. Conclusions could be summarized as follows: 1) Students' mathematical errors on proof problem solving and LC learning structures have the same nature. 2) Structures in items of students' mathematical errors and misleading factor structures in cognitive tasks affect mental processes with the same activation mechanism. 3) LC learning structures were activated preferentially in knowledge structures by F operator. With the same activation mechanism, the process students' mathematical errors were activated firstly among conceptions could be explained.

• Journal of Korea Port Economic Association
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• v.26 no.4
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• pp.1-18
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• 2010

The purpose of this paper is to evaluate the green logistics of Korea enterprises. According to participate pan-nationally about environment problems, the field of logistics is required to transfer green logistics like increase efficiency of using energy and construct economic systems. And also environment-friendly policies of enterprises are playing important role. So authors selected and analysed factors through precedent study and questionnaire. Selected factors are cultivation about environment-friendly policy awareness to employees, Utilization environment-friendly resources, decrease of atmosphere pollution substance, company's promotion of outside environment-friendly policy. In order to shed light on these problem, fuzzy AHP method is adopted and the factor of cultivation about environment-friendly policy awareness to employees is the highest weight. And also result of the highest weight between enterprises that set policies about green logistics and factors' are The Korean Air, Glovis, Korea Express synthetically.

• Journal of Navigation and Port Research
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• v.41 no.6
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• pp.401-408
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• 2017

The Street Turn system in South Korea has been developing continuously with the advancement of information technology; however, this has not lead to an increase of the Street Turn transportation volume. As a result, this study presents the decision-making factors for using the system from the standpoint of users of the existing Street Turn transportation system. The people who have used domestic Street Turn transportation services or who are working in a shipping company were analyzed using Fuzzy-AHP. A total of five major factors and 17 detailed factors were derived from this analysis. As a result, timeliness was selected as the most important major factor, and in particular, the information provision time (0.207) was selected as the most important factor, followed by platform use process (0.079), and number of participating shippers (0.074).

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.2
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• pp.135-144
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• 2009

Fuzzy hybrid control technique with a smart tuned mass damper(STMD) was proposed in this study for the suppression of wind-induced motion of a tall building. To develop the effective control algorithm for a STMD, skyhook and groundhook control algorithms were employed. Usually, skyhook controller can effectively reduce STMD motion and groundhook controller shows good control performance for the reduction of building responses. In this study, fuzzy hybrid controller, which can determine an optimal weighting factor for combining two controllers in real time, was developed to improve the control performance of conventional hybrid controller using weighted sum approach. A 76-story office building was used as an example structure to investigate the performance of the proposed controller. A magnetorheological(MR) damper was used to develop a STMD and the control performance of STMD was evaluated comparing with the passive and active TMD. The numerical studies show that the control effectiveness of a STMD is significantly superior to that of the conventional TMD. It is also shown that fuzzy hybrid controller can effectively adjust skyhook and groundhook control algorithms and reduce both responses of STMD and building.

• Journal of Korea Port Economic Association
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• v.28 no.2
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• pp.29-41
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• 2012

Competition between international Hub ports has been more and more intense. In order to invigorate itself, Gwang-Yang port has been making multilateral efforts. However, it has not still reached 300Millions TEU which is the standard to be permitted as a self-reliance Hub port. Therefore, a functional modification of berth should be considered. This study suggests to transform container berths to general berths. This article is focused on reserve berth mode of Gwang Yang hub port and selected three kinds of berths as alternative subjects of the study: general berth, exclusive berth, and multipurpose berth. This research has conducted that The subjects of the survey were in relation with Logistics as professional mutually group about Gwang-Yang hub port. The measurements of this survey were measure section and factor. Also, Fuzzy AHP(Analytic Hierarchy Process) was applied to the survey. According to the result, by measuring weight values of alternatives, the best favored one was multipurpose berth expect stability (32.6%), Exclusive berth was graded the most among the alternatives. Also, based on total weight value, the order of priority is as follows: multipurpose berth(38.2%), exclusive port(33.7%), general berth(28.1%).

• The Transactions of the Korea Information Processing Society
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• v.3 no.3
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• pp.449-459
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• 1996

The main goal of this paper is to introduce a novel definition for fuzzy mathematical morphology and a neural network implementation. The generalized- mean operator plays the key role for the definition. Such definition is well suited for neural network implementation. The first stage of the shared-weight neural network has adequate architecture to perform morphological operation. The shared- weight network performs classification based on the features extracted with the fuzzy morphological operation defined in this paper. Therefore, the parameters for the fuzzy definition can be optimized using neural network learning paradigm. Learning rules for the structuring elements, degree of membership, and weighting factors are precisely described. In application to handwritten digit recognition problem, the fuzzy morphological shared-weight neural network produced the results which are comparable to the state-of art for this problem.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1587-1599
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• 2017

This paper proposes a real-time implementation of an optimal operation of a double stage grid connected wind power system incorporating an active power filter (APF). The system is used to supply the nonlinear loads with harmonics and reactive power compensation. On the generator side, a new adaptive neuro fuzzy inference system (ANFIS) based maximum power point tracking (MPPT) control is proposed to track the maximum wind power point regardless of wind speed fluctuations. Whereas on the grid side, a modified predictive current control (PCC) algorithm is used to control the APF, and allow to ensure both compensating harmonic currents and injecting the generated power into the grid. Also a type 2 fuzzy logic controller is used to control the DC-link capacitor in order to improve the dynamic response of the APF, and to ensure a well-smoothed DC-Link capacitor voltage. The gained benefits from these proposed control algorithms are the main contribution in this work. The proposed control scheme is implemented on a small-scale wind energy conversion system (WECS) controlled by a dSPACE 1104 card. Experimental results show that the proposed T2FLC maintains the DC-Link capacitor voltage within the limit for injecting the power into the grid. In addition, the PCC of the APF guarantees a flexible settlement of real power exchanges from the WECS to the grid with a high power factor operation.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.169-177
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• 2015

This paper described a fuzzy comprehensive evaluation method and implemented assessment system for multi-layer decision making. The proposed method is a assessment before bidding through the key questions using fuzzy comprehensive evaluation method and the entropy weights. The key questions are given by the wider investigation of major sports event organizers. The paper carried out evaluation of single factor and fuzzy comprehensive evaluation from low layer to high layer step by step. In order to verify the effectiveness of proposed method, we built the sports event management service platform (SEMSP) for assessment of applicant city. This method represents a unified one of the quantitative results and the qualitative results based on the judgment of experts.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.905-910
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• 2012

In early 1990s, the Sea & Air Transport Cargoes (SATC) was increased annually with more than 50% rate due to the rising trade between Korea and China. However, after that, the increasing rate of the SATC was slowdown from the late 1990s, furthermore, recently it became sluggish and declined. This phenomenon is totally different compared to the skyrocketing trade volumes between two countries. In this respect, to forecast the SATC, draw out the factors for activation, and calculate the weight of priority of these factors are urgently needed. To achieve the research objectives, the ARIMA and Fuzzy-AHP were used as research methodology. The estimated volume of SATC using the data from year 2007 to 2012 on the ARIMA model, will be reached approximately 33,000 tons in year 2015. In the mean time, For drawing out and weighing the activation factors for SATC, the Fuzzy-AHP was adopted. As a result, 'Sea & Air transportation-related information system policies' is the most important factor among the principle criteria, and 'the construction of consolidation logistics center' is the most important factor among the 12 sub-principle criteria.