• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.585-596
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• 2001

In this paper, a new stream cipher algorithm based on the chaos theory is proposed and is applied to a Web security system. The Web security system is composed of three parts： certificate authority (CA), Web client, and Web server. The Web client and server system include a secure proxy client (SPC) and a secure management server (SMS), respectively, for data encryption and decryption between them. The certificate is implemented based on X.509 and the RSA public key algorithm is utilized for key creation and distribution to certify both the client and server. Once a connection is established between the client and server, outgoing and incoming data are encrypted and decrypted, respectively, using one of the three cipher algorithms： chaos, SEED, and DES. The proposed chaos algorithm outperforms the other two conventional algorithms in processing time and complexity. Thus, the developed Web security system can be widely used in electronic commerce (EC) and Internet banking.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.872-876
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• 2009

The government has funded various types of projects to promote small and medium companies' computerization for several years. Most of these government-supported funds have been free and given small and medium firms good opportunities. The government has made various effects to manage results of these government-supported projects. We have not seen any noticeable research on the performance evaluation of government-supported projects for small and medium companies' computerization. This research proposes an approach that performance evaluations are made in different time based on evaluation area of government-supported information policy. The empirical study has been made by correlation analysis and has shown that the correlations among measurement factors are significant enough. The performance evaluation for government-supported information policy has been made differently in time depending on evaluation subjects such as organizational strategies, internal operations, supporting processes. Th experimental study shows that performance evaluations on organizational strategies, internal operations, supporting processes should be made respectively in long term(step3), mid term(step2), and short term(step1).

• Proceedings of the CALSEC Conference
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• 1999.07a
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• pp.277-299
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• 1999

Since Chrysler Motor Co. had experienced the digital development system in the beginning of 1990's, most of leading automobile companies are trying to apply a digital information system for their own business process reengineering based upon concurrent engineering system from product planning phase. This is called as virtual DMU(Digital Mock-Up) system instead of the traditional PMU(Physical Mock-Up) system. By using the virtual prototype, all of the design requirements and system specifications can be checked, changed and optimized more quickly and more efficiently. This paper consists of five chapters for the DMU information system. In the 1$^{st}$ chapter, the principle of digital design system is suggested by using four basic modules such as product design module, process design module, manufacturing system design module and central control module. The basic scheme of DMU is introduced with the benefits of application in the chapter 2. In the chapter 3, a digital design process of new car development is explained with the detailed DMU design and design review processes. In the chapter 4, the practical DMU manufacturing techniques and applications are introduced as CAD/CAM analyses, DPA(Digital Pre-Assembly)reviews for development, production, operation and maintenance phases, digital tolerance analyses and digital factory analyses for assembling line simulation, automated robot welding processes, production jig ＆ fixtures and painting process simulation. Finally, the activities of digital design support; CAS-styling, CAE-engineering and CAT-testing are summarized for design optimization in the chapter 5. As today's automobile manufactures and related business organizations are struggling to compete in the global marketplace, they are concentrating on efficient use of DMU information system to reduce the new car development cost, to have shorten the delivery schedule and to improve product design quality. To meet the demand of those automobile industries on digital information systems, the CALS(Computer aided Acquisition and Logistics Support) and EC(Electronic Commerce)initiative has been focused as a dominant philosophy in defense ＆ commercial industries, specially automobile industries.s.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2003.11a
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• pp.239-250
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• 2003

In this research, we propose a hybrid group decision support mechanism (H-GDSM) based on Fuzzy AHP (Analytic Hierarchy Process) and FCM (Fuzzy Cognitive Map). The AHP elicits a corresponding priority vector interpreting the preferred information among the decision makers. Corresponding vector was composed of the pairwise comparison values of a set of objects. Since pairwise comparison values are the judgments obtained from an appropriate semantic scale. However, AHP couldn't represent the causal relationship among information, which were used by decision makers. In contrast to AHP, FCM could represent the causal relationship among variables or information. Therefore, FCMs were successfully developed and used in several ill-structured domains, such as strategic decision-making, policy making, and simulations. Nonetheless, many researchers used subjective and voluntary inputs to simulate the FCM. As a result of subjective inputs, it couldn't avoid the rebukes of businessman. To overcome these limitations, we incorporated the Fuzzy membership functions, AHP and FCM into a H-GDSM. In contrast to current AHP methods and FCMs, the H-GDSM method developed herein could concurrently tackle the pairwise comparison involving causal relationships under a group decision-making environment. The strengths and contributions of our mechanism were 1) handling of qualitative knowledge and causal relationships, 2) extraction of objective input value to simulate the FCM, 3) multi-phase group decision support based on H-GDSM. To validate our proposed mechanism we developed a simple prototype system to support negotiation-based decisions in electronic commerce (EC).

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.4
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• pp.324-335
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• 2001

Information systems, which support information security functions such as CALS and EC systems, should have cryptographic functions for information in order to storage and communicate securely. Additionally, including recovery of lost keys, lots of cryptographic keys should be securely managed. In this paper, we present some results of development of a key recovery system for recovery of encrypted data. The proposed system, in a type of key encapsulation approach, confirms to NIST's RKRP(Requirements for Key Recovery Products) that is a defecto international key recovery standard, as well as CC 2.0 that is a international security evaluation criteria. A message sender secretly choices two or more key recovery agents from a pool of key recovery agents. The key recovery information is generated by using the recovering key, random keys and public keys of the chosen agents. A message receiver can not know which key recovery agents are involved in his key recovery service. We have developed two versions of prototype of key recovery system such as C/Unix and Java/NT versions. Our systems can be used for recovery of communicating informations as well as storing informations, and as a new security service solution for electronic commerce service infrastructures.