• Journal of Intelligence and Information Systems
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• v.10 no.2
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• pp.91-109
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• 2004

This study investigates the effectiveness of a hybrid approach using fuzzy sets that describe approximate phenomena of the real world. Compared to the other existing techniques, the approach handles inexact knowledge in common linguistic terms as human reasoning does it. Integration of fuzzy sets with case-based reasoning (CBR) is important in that it helps to develop a successful system far dealing with vague and incomplete knowledge which statistically uses membership value of fuzzy sets in CBR. The preliminary results show that the accuracy of the integrated fuzzy-CBR approach proposed for this study is higher that of conventional techniques. Our proposed approach is applied to corporate bond rating of Korean companies.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.12
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• pp.1682-1687
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• 2020

We study the problem of sampling a subset of nodes of graphs for bandlimited graph signals such that the signal values on the sampled nodes provide the most information in order to reconstruct the original graph signal. Instead of directly minimizing the reconstruction error, we focus on minimizing the upper bound of the reconstruction error to reduce the complexity of the selection process. We further simplify the upper bound by applying useful approximations to propose a low-weight greedy selection process that is iteratively conducted to find a suboptimal sampling set. Through the extensive experiments for various graphs, we inspect the performance of the proposed algorithm by comparing with different sampling set selection methods and show that the proposed technique runs fast while preserving a competitive reconstruction performance, yielding a practical solution to real-time applications.

• Review of KIISC
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• v.17 no.4
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• pp.56-73
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• 2007

2002년 11월 대한민국 전자정부의 공식출범을 비롯하여 최근 IT 839전략 등에 힘입어 차세대 IT 분야의 급속한 발전은 바야흐로 유비쿼터스 컴퓨팅 시대로의 진입을 가속화 하고 있다. 최근에는 이것을 뒷받침 하는 기술 분야의 하나인 BcN(Broadband Convergence Network) 역시 그 연구에 박차를 가하고 있으며, 이것의 단말기 역할을 하는 이동성 있는 모바일 폰 기술 역시 급속도로 발전하고 있다. 하지만, 이런 기술 발전과는 달리 그 이면에는 개인정보보호의 침해라는 문제가 있다. 기술의 발전에 비례해서 개인정보 침해 역시 고도화, 전문화되어 급속도로 증가하고 있는 것이다. 본 고에서는 개인정보의 개념부터 먼저 살펴본 후, 모바일 폰의 표준화 현황 및 기반 기술과 응용 서비스 기술을 분석하여 문제점을 도출하고 그 대응 방안을 모색한다. 현재 서비스들이 하나의 소형화된 기기로 집적화되어 가고 있는 추세에서 휴대형 정보기기에서의 개인정보보호를 위한 대안이 절대 한 가지 메카니즘 만으로는 부족하며, 종합적인 보안 기술의 집합체를 이루어야 한다는 사실을 알 수 있게 된다.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.334-337
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• 2001

현재 웹에서는 공개키 암호 알고리즘을 이용한 일반적인 전자서명을 사용하고 있으나 웹에서 표준화가 되어 가고 있는 XML을 이용한 전자서명 기법이 W3C에서 제안되어 표준화가 진행되고 있다. 이는 SGML의 부분집합으로서 문서의 내용에 관련된 태그를 사용자가 직접 정의할 수 있다. 이런 확장성이 뛰어난 XML을 이용하여 기업 간에 사용되는 EDI 문서를 표현함으로써 업무처리시간 및 비용을 절감하고, 품질을 향상시키기 위한 대안으로 많은 기업들이 EDI 시스템을 사용하여 인터넷으로 인해 세계 어느 곳에서나 필요한 정보를 볼 수 있게 되었다. 이러한 시스템들은 네트워크를 통해 정보가 전달되므로 보안에 아주 예민하다. XML 표준전자문서의 인중이나 신뢰성이 보장되지 않는다면, 전송중 문서의 조작, 도청 및 오용 등과 같은 위험 때문에 그 사용이 제한된다. 본 논문에서는 그러한 위협을 방지하고 XML 표준전자문서의 신뢰성 있는 전송을 보장차기 위하여 전자 문서 교환에 있어서 중요하다고 할 수 있는 XML 전자서명 시스템에 대하여 연구하였다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.20 no.1
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• pp.21-31
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• 2002

This study applied each Neural Networks theory and Fuzzy Set theory to improve accuracy in remotely sensed images. Remotely sensed data have been used to map land cover. The accuracy is dependent on a range of factors related to the data set and methods used. Thus, the accuracy of maps derived from conventional supervised image classification techniques is a function of factors related to the training, allocation, and testing stages of the classification. Conventional image classification techniques assume that all the pixels within the image are pure. That is, that they represent an area of homogeneous cover of a single land-cover class. But, this assumption is often untenable with pixels of mixed land-cover composition abundant in an image. Mixed pixels are a major problem in land-cover mapping applications. For each pixel, the strengths of class membership derived in the classification may be related to its land-cover composition. Fuzzy classification techniques are the concept of a pixel having a degree of membership to all classes is fundamental to fuzzy-sets-based techniques. A major problem with the fuzzy-sets and probabilistic methods is that they are slow and computational demanding. For analyzing large data sets and rapid processing, alterative techniques are required. One particularly attractive approach is the use of artificial neural networks. These are non-parametric techniques which have been shown to generally be capable of classifying data as or more accurately than conventional classifiers. An artificial neural networks, once trained, may classify data extremely rapidly as the classification process may be reduced to the solution of a large number of extremely simple calculations which may be performed in parallel.

• Journal of Korean Society of Transportation
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• v.22 no.2 s.73
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• pp.121-130
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• 2004

In these days, multiple-path generation method is highly demanded in practice and research areas, which can represents realistically travelers behavior in choosing possible alternative paths. The multiple-path generation algorithm is one of the key components for policy analysis related to ATIS, DRGS and ATMS in ITS. This study suggested a method to generate multiple Possible paths from an origin to a destination. The approach of the suggested method is different from an other existing methods(K-shortest path algorithm) such as link elimination approach, link penalty approach and simulation approach. The result of the multi-label vine-building shortest path algorithm(MVA) by Kim (1998) and Kim(2001) was used to generate multiple reasonable possible paths with the concept of the rational upper boundary. Because the MVA algorithm records the cost, back-node and back-back node of the minimum path from the origin to the concerned node(intersection) for each direction to the node, many potential possible paths can be generated by tracing back. Among such large number of the potential possible paths, the algorithm distinguishes reasonable alternative paths from the unrealistic potential possible paths by using the concept of the rational upper boundary. The study also shows the very simple network examples to help the concept of the suggested path generation algorithm.

• Management & Information Systems Review
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• v.35 no.3
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• pp.173-193
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• 2016

The aim of this paper is to extend the TOPSIS(Technique for Order Preference by Similarity to Ideal Solution) to the fuzzy environment for solving the disaster recovery priority decision problem in credit bureau business information system. In this paper, the rating of each information systems and the weight of each criterion are described by linguistic terms which can be expressed in trapezoidal fuzzy numbers. Then, a vertex method is proposed to calculate the distance between two trapezoidal fuzzy numbers. According to the concept of the TOPSIS, a closeness coefficient is defined to determine the ranking order of all information systems. The combination between the fuzzy set and TOPSIS brings several benefits when compared with other approaches, such that the fuzzy TOPSIS require few fuzzy judgements to parameterization, which contributes to the agility of the decision process, it does not limit the number of alternatives simultaneously evaluated, and it does not cause the ranking reversal problem when a new alternative is included in the evaluation process. This paper is demonstrated with a real case study of a credit rating agency involving 9 evaluation criteria and 9 credit bureau business information systems assessed by 6 evaluators, and provide the systematic disaster recovery framework for BCP(Business Continuity Planning) to practitioner. Finally, this paper show that the procedure of the proposed fuzzy TOPSIS method is well suited as a decision-making tool for the disaster recovery priority decision problem in credit bureau business information system.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.222-228
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• 2010

In this paper, we propose a optimization approach for the Electric Locomotive Overhaul Maintenance Facility (ELOMF), which aims at the simulation optimization so as to meet the design specification. In simulation design, we consider the critical path and sensitivity analysis of the critical (dependent) factors and the design (independent) parameters for the parameter selection and reduction of the metamodel. Therefore, we construct the multi-objective non-linear programming. The objective function is normalized for the generalization of design parameter while the constraints are composed of the simulation-based regression metamodel for the critical factors and design factor's domain. Then the effective solution procedure based on the pareto optimal solution set is proposed. This approach provides a comprehensive approach for the optimization of Train Overhaul Maintenance Facility(TOMF)'s design parameters using the simulation and metamoels.

• Journal of the Korea Society for Simulation
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• v.16 no.2
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• pp.45-54
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• 2007

In this article, we propose a different modeling approach, which aims at the simulation optimization so as to meet the design specification. Generally, Multi objective optimization problem is formulated by dependent factors as objective functions and independent factors as constraints. However, this paper presents the critical(dependent) factors as objective function and design(independent) factors as constraints for the selection of design factors directly. The objective function is normalized far the generalization of design factors while the constraints are composed of the simulation-based regression metamodels fer the critical factors and design factor's domain. Then the effective and fast solution procedure based on the pareto optimal solution set is proposed. This paper provides a comprehensive framework for the system design using the simulation and metamodels. Therefore, the method developed for this research can be adopted for other enhancements in different but comparable situations.

• Journal of the Korea Society of Computer and Information
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• v.12 no.3
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• pp.115-122
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• 2007

The aim of this study is to identify the effect that the blended learning has on the learning achievement of computer education in high school. To get the goal, 136 students were allocated into the experiment group(68 students) with the blended class and the control group(68 students) with the traditional face-to-face class. After identifying the homogeneity of two groups in learning achievement by analyzing the pre-test, the experiment was performed. The result of this research is as follows. Significant difference was found in the learning achievement of post-test between the experiment group and the control group (t=-3.16, p=.0019). This result underlies the potential of blended learning in computer education. It will be important for designing the class for computer education in high school.