• Journal of Korea Multimedia Society
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• v.8 no.7
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• pp.988-999
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• 2005

As the Internet continues to have the commercial trade changed, the method of payment is one of critical components to conduct successful businesses through the internet. An electronic cash has all of the characteristics of a traditional commodity cash and ensures the security for all transactions. Accordingly an internet billing system based on the electronic cash is expected as the secure and efficient payment method for the future electronic commerces. The digital contents such as digital merchandise and services have the characteristic that both the delivery of merchandise and the payment of money can be accomplished on the same network and are helpful to idealize the design of the electronic commerce system. In this paper, Anonymity got to be possible by using a virtual ID in the process of payment, the payment steps were decreased by being processed on the same network, and the efficiency and the security were guaranteed by decreasing the frequency of the coding and communication.

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.757-764
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• 2001

The increase of electronic commerce leads to the increasing attention to the way customers pay and a large number of researches on payment system. Recently many researches on a system which provides anonymity in order to protect user\`s privacy have been carried out. And some potential problems from that system are being reviewed by anonymity control system. This thesis will include the following. First, I want to analyze the old scheme related to divisible and examine general ideas of anonymity control. Second, I propose a new blind signature in addition to KCDSA, the standard digital signature in Korea. The last one I want to propose is a new electronic cash system with the divisible for more efficient use of electronic cash which can control anonymity with the help of trustee.

• The Journal of Information Technology
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• v.4 no.2
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• pp.155-174
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• 2001

Dramatic changes are beginning to occur in payment system according to increase electronic commerce. and so electronic money as a new payment system are increase role in new and innovative systems. There are two type Electronic money as a IC card type and network-type. Advanced card technologies such as IC-card are playing an increasingly important role in new and Innovation system. The merit of IC-card are more capacity, more secure, more reliable, quick and easy to update, secure offline processing, enabling technology etc than magnetic stripe card. And so many countries began using experiment of IC- card and our country began October 13 in Cheju island. Then there are four types using-experiment (K-cash, VISA-cash, A-cash, MONDEX) in Korea. There are some problems such as standards, widely using, high cost, double investment etc. I think that important things in IC-card using is an international- standardizations and issuing corporation.

• Journal of the Korea Computer Industry Society
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• v.3 no.3
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• pp.369-382
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• 2002

The increase of vehicles stagnations leads to the increasing attention to the way customers pay and a large number of Projects on electronic cash system. Tranport system is comprised of a number of advanced technologies, including information processing, communications, control, and electronics. Recently many research on a system which provides contact in order to protect driver's vehicle passage have been carried out. And some potential problems from that system are being reviewed by electronic cash system. In this papers, we suggest RF protocol developing technology using the concept of electronic cash. ATM electronic cash developing is consist of component of pre-developed coin throw, integration of component using its, and production of more requirement-satisfactory ITS solution. Result increase 15-40% pre-type vehicles stagnations. Especially, we expect this proposed concept would be well adapted to our national environments.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.1
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• pp.55-66
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• 2002

Electronic cash system based on anonymous coins have been invented by David Chaum. However, von Solms and Naccache discovered that such anonymous coins also very well suited to support criminals in Blacoailing. In this paper, we suggest a method that a client informs a bank of the information about blackmailing attack by using Schnorr identification protocol of XTR version at the stage of identification, whenever he is blackmailed. In general, blackmailing is the most serious among the various drawbacks of electronic cash system. Especially, blackmiling to be done when the client is kidnapped brings a fatal result to electronic cash system. But if the Schnorr identification protocol of XTR version is used, we can efficiently defeat blackmailing without assumption required in the existing method to defeat blackmailing.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.287-292
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• 2004

BOCC(Brand's Offline Cash with a Counter) is useful in mobile environments, but it has the possibility of attacking amount data in a smart card. To insert the upper & lower limitation of amount into a token data decreases the level of risk. If upper and lower values are same, it means a fixed amount token. Since refund can more often happen in on-line commerce, refundability is added. BOCC is based on Discrete Logarithm Problem, needs exponential computations. But mobile terminals like cell phones have low computational power. As a result, ECC is used to Improve the performance supporting same security level.

• Journal of Advanced Navigation Technology
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• v.11 no.1
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• pp.112-117
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• 2007

The Internet leads the transformation of the all-over social life with its radical diffusion and development. Moreover, it can be more focussed on the electronic commerce using the Internet - a new type of commerce, which is diffusion and developing. In the paper, we propose an electronic payment protocol with a network-type electronic-cash based on Public Key Infrastructure(PKI). The proposed protocol overcomes the problem of NetBill which deals with only contents and can't ensure anonymity. It also prevents illegal copy and distribution and insures the greatest safety by means of giving a certification number to the digital contents offered on the on-line.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1994.11a
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• pp.35-44
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• 1994

We propose an undeniable digital signature scheme which is practical since it has less computation and communication overhead than Chaum's one. We expect that this protocol be useful to develop secure systems such as electronic contract system, electronic mail system and electronic cash system.

• Journal of Digital Contents Society
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• v.5 no.1
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• pp.1-6
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• 2004

Electronic cash is used as a payment tool for contents purchase in mobile electronic commerce environment. In order to protect customer`s privacy, we use blind signature. Blind signature has an anonymity property since it does not allow connection between customer`s ID and customer`s message. In this paper, we propose an blind signature scheme using elliptic curve algorithm based on Cap Diffie-Hellman Problem. Proposed scheme efficiently improved against existing blind signature scheme by reducing communication and computation time of the process.

• The Journal of Information Systems
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• v.14 no.2
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• pp.277-292
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• 2005

This paper uses a data mining approach to develop bankruptcy prediction models suitable for traditional (off-line) companies and electronic (on-line) companies. It observes the differences in the composition prediction models between these two types of companies and provides interpretation of bankruptcy classifications. The bankruptcy prediction models revealed the major variables in predicting bankruptcy to be 'cash flow to total assets' and 'gross value-added to net sales' for traditional off-line companies while 'cash flow to liabilities','gross value-added to net sales', and 'current ratio' for electronic companies. The accuracy rates of final prediction models for traditional off-line and electronic companies were found to be $84.7\%\;and\;82.4\%$, respectively. When the model for traditional off-line companies was applied for electronic companies, prediction accuracy dropped significantly in the case of bankruptcy classification (from $70.4\%\;to\;45.2\%$) at the level of a blind guess ($41.30\%$). Therefore, the need for different models for traditional off-line and electronic companies is justified.