• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.6
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• pp.69-78
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• 2004

During the last decade, security models have been defined for two- and three-parity key exchange protocols. Currently there is a growing research interest in security models for group key management schemes. While various security models and provably secure protocols have been proposed for distributed group key exchange schemes, no results are hewn for centralized group key distribution schemes in spite of their theoretical and practical importance. We describe security requirements and a formal security model for centralized group key distribution scheme: we define the model on the channel controlled by adversaries with the ability of strong user corruption. In the security model, we propose a conversion module which can transform centralized tree-based group key distribution schemes in the literature to provably secure centralized tree-based group key distribution schemes.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.6
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• pp.817-825
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• 2018

Recently, drones have been used in various field to overcome time and space limitations. However, single drone still has a lot of restriction on transportation wight and travel time. Therefore many studies have been conducted to increase the utilization by swarm of drones. Many things should be additionally considered in order to operate swarming drones securely. Especially the group key management is a challenging research topic in tactical domain due to existence of adversary that has anti-drone skill. In this paper, we proposed an efficient group key management scheme for tactical swarming drone networks where an adversary equipped with anti-drone skills exists. The group key can be updated with a small number of message exchange compared to other convenience schemes. The numerical and simulation results demonstrate that the proposed scheme manages the group key efficiently and securely.

• Journal of Korean Society for Quality Management
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• v.26 no.3
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• pp.108-129
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• 1998

Many empirical research surveys have su, pp.rted that Organizational Citizenship Behavior(OCB) is influenced by or closely related with leadership styles. The primary purpose is to test the moderating effects of structural factors (formalization, centralization) and personal factors(growth needs, sex, age, tenure, rank, occuption, school carrer) between 2 leadership styles and 2 OCB factors. For the analytical purpose of this article, Fisher's Z-transformation and SGC(split groups correlations) methods were introduced. Generally 2 leadership styles are found to influence on altruism and conscientiousness respectively. Out of 36 cases, only 2 cases were significant in moderating effects. Based on empirical results, there is no moderating effects in conscientiousness. But altruism is found to more closely related with employee-centered leadership in low centralized group than in high centralized group, and more closely related with job-centered leadership in low growth-needs group than in high growth-needs group.

• Journal of the Korea Society of Computer and Information
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• v.20 no.10
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• pp.1-5
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• 2015

Based on the dual hardware and software with distributed recovery blocks, the centralized type fault tolerant store management system(SMS) was proposed. As a result of trade off study related to mutiplex hardware system design, dual single board computer(SBC) was adapted. To verify redundancy function of the proposed structure, the prototype SMS and weapon simulator were used. The proposed SMS operated normally without being affected by a primary SBC failure. The switching time from primary SBC to shadow SBC was within 200 ms. The reliability of the proposed SMS was predicted and compared with the non fault tolerant SMS, thereby it was proved that the proposed SMS has a higher reliability than the non fault tolerant system within effective range.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.152-156
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• 2001

In this paper we propose a secure multicast key distribution protocol using OFT(One-way Function Trees). The proposed protocol is a hybrid scheme of DKMP(Distributed Key Management Protocol) that guarantees all group member's participation for generating a group key, and CKMP(Centralized Key Management Protocol) that makes it easy to manage group key and design a protocol. Since the proposed protocol also computes group key using only hash function and bitwise-XOR, computational overhead ran be reduced. Hence it is suitably and efficiently adaptive to dynamic multicast environment that membership change event frequently occurs.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.68
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• pp.37-50
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• 2001

Although the study of OCB has increased greatly in recent years, a little works have focused on the relationship between leadership and extrarole behavior, and the moderating effects of the situational factors on the relationship between two factors. For the analytical purpose of this article, Fisher＇s Z-transformation and SGC(split groups correlations) methods were introduced. Generally 2 leadership styles are found to have influenced on altruism and conscientiousness respectively. Out of 36 cases, only 2 cases were significant in moderating effects. Based on empirical results, there is no moderating effects in conscientiousness. But altruism is found to be more closely related with employee-centered leadership in low centralized group than in high centralized group, and more closely related with job-centered leadership in low growth-needs group than in high growth-needs group.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1451-1457
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• 2013

Recently, new concept of energy systems such as microgrid, smart grid, supergrid, and energy network has been introducing. In this paper, the concept of the centralized micro-energy network, which is an energy community of a building group without district heating system, is introduced. In addition, a mathematical model for optimal operation of the micro-energy network as a main function of an energy management system (EMS) for the micro-energy network is proposed. In order to show the validation, the proposed model is tested through the simulation and analyzed.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.1
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• pp.100-108
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• 2003

By choosing Multicast for transmission of educational contents in the Remote Educational System, we can reduce the server load and increase network bandwidth utilization. We design and implement Multicast Middleware for the Remote Educational System in this paper. There are three characteristics in this Multicast Middleware: 1) Through Centralized Multicast Group Management for passive members, it allows a host to make multicast group, which is composed of receivers, called Group Member and who are chosen by the host, called group Maker. Because, all groups are created by the Group Maker in Centralized Group Management, Group Member's join action will be passive 2) Maintenance and recovery of multicast group information in order to restore from exception and crash; the maintenance and recovery mechanism of Group Maker is distinct from that of Group Member. 3) The mechanism which enables to transmit large size multimedia data through multicasting and remove additional copy operation through shared buffer. Fragmentation/de-fragmentation for large data delivery results in additional copy operation in user level. But by using user level shared buffer, it can be done without user Bevel copy operation. By applying to Remote Educational environment which consists of 30 PCs and Fast Ethernet, we can examine the efficiency of this middleware, which can transmit 18frames/sec movie which resolution 320 $\times$ 120 pixels, 128Kbps encoded sound data and some text data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7C
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• pp.733-742
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• 2003

Unlikely unicast transmission, there are many elements that threaten security. Thus, key management of creating and distributing group keys to authorized group members is a critical aspect of secure multicast operations. To offer security in multicast environment, the recent researches are related to most group key distribution. In this thesis, we propose a group key management protocol for efficient, scalable, and multicast operation. This proposed protocol architecture can distribute traffic centralized to the key server. since the group key rekeyed by sub-group manager. The detailed simulation compared with other group key management protocol show that the proposed group key management protocol is better for join, leave, and data latency.

• Journal of the Korea Convergence Society
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• v.7 no.4
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• pp.59-66
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• 2016

This study analyzed the relationship between the convergence performance in hospital. This study examined previous research and calculated centralized index using diagnosis related groups. In addition, multiple regression analysis was used based on LOS in order to understand the effect of focused strategy which quality of medical inpatient service. The centralized level was examined by analyzing national inpatient sample data using 'Internal Herfindahl-Hirshman index' This study is significant because it reviewed medical inpatient service quality by measuring hospital centralized level which has been rarely studied before Korea.