• Journal of information and communication convergence engineering
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• v.5 no.3
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• pp.194-199
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• 2007

In this paper, a slotted CDMA_ALOHA protocol with hybrid ARQ is proposed for the wireless CDMA communication networks. The proposed protocol combines the characteristics of the slotted ALOHA, CDMA, and the hybrid ARQ, in order to increase the throughput by reducing the number of retransmissions when the channel experiences heavy traffic. The main feature of the proposed protocol is the utilization of the forward error correction capability to correct errors that appear after the CDMA dispreading of the packets. The base station does not need to ask so often for retransmission of erroneous packets. It will request for retransmission only when the FEC capability is exceeded. The performance of the proposed protocol is analyzed by considering the packet collision probability as well as the bit error probability. The numerical results show that the system throughput is closely related to the bit error rate of the wireless link and the FEC coding rate.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.756-758
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• 2015

사물인터넷 환경에서 접근제어는 다양한 단말간 통신이 발생하고, 더 많은 객체간의 통신이 이루어지기 때문에 전통적인 접근제어와 차별화된 방법이 필요하다. 본 논문에서는 사물인터넷 환경에서 접근제어를 위하여 사용자 및 서비스 요청자의 인증정보 및 접근 권한 정보를 하나의 토큰으로 제공하며, 한번의 인증으로 세션을 유지하여 리소스 서비스에 접근할 수 있는 토큰 구조 및 관리 기술에 대해 연구하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.169-177
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• 2007

Existing wireless access (mobile) routers are based commonly on the network address and port translation (NAPT) technique which permits simultaneously sharing a subscriber's connection to the network with multiple users. However, the NAPT architecturally makes the users invisible on the network side, thus becoming a user-oriented connection technique. In this paper, we propose a novel service provider-oriented unlicensed nomadic access relay station (WiNNERS) for helping wireless broadband network service providers to make their business more lucrative by accommdating unlicensed band users as subscribers into their network. The WiNNERS offers service providers the capability to directly manage each of the unlicensed band users at the network side. This direct management allows the service providers to flexibly and simply handle QoS, access control, and billing for each user. In order to distinguish each of the unlicensed band users the WiNNERS constructs a virtual tunnel from each user's terminal to the network access router using connection identifiers which is defined for service flow management within the WiBro system, Consequently, our proposed service provider-oriented relay station can be included into the WiBro network system with minimum modifications.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.211-215
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• 1997

Localized communication networks for office automation, security monitoring, environmental management of buildings, computer communications, and other applications enjoy every increasing demand. This paper proposes a direct sequence spread spectrum communication system for use in power line data transmission. Advantages of power distribution circuits include reasonably universal coverage and easy access vis a standard wall plug. Disadvantages include limited communication bandwidth, relatively high noise levels, and varying levels of impedance, noise, and attenuation. Spread spectrum signalling provides immunity to narrow-band signal impairments and multiplexing capability. Our prototype power line communication module supports completely physical and data link layers based on the international standard ISO 10368 for reliable high-speed power line communication system. Moreover it provides useful functions to compose a plant monitoring and control system. All the circuits of the communication module are included in one compact circuit. Thus a functional communication system for the power line plant monitoring and control is implemented.

• Asia pacific journal of information systems
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• v.5 no.1
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• pp.219-235
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• 1995

Complexity of some problems often transcends the problem solving capability of human individuals. As such, we cannot but take a collaborative approach to those complex problems. Collaboration while using computing systems can take place through shared objects. However, current commercial DBMSs do not provide a satisfactory control for concurrent access to objects shared by collaborators. A new concurrency control scheme is proposed which will help a group of people work in a more collaborative and natural way. The idea of softlock is refined into three different kinds of softlocks and the roles of collaborators are taken into account in the proposal of the new scheme. Although these softlocks are illustrated together with read/write hardlocks in this paper, the use of softlocks can be extended to be exploited with other kinds of hardlocks, for example, of granularity locking.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.3
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• pp.150-154
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• 2011

The technology to build high speed network using low cost DSL in the areas where the cost to build high speed network is high and the network environment is not very accommodating is important in providing the high speed network that meets the user demand and utilizing the network resources in an efficient way. This study presents development of the link aggregation equipment that performs the access control and firewall functions for packet processing based LAN users. The equipments developed support up to 5 line link aggregation as opposed to current 2 line link aggregation. The equipments also allow the use of high speed network in the areas where the network environment is not very accommodating. Also, the fail-over function is added to each line to provide reliability and the self-security function is enhanced to protect the network from unauthorized use and prevents waste of network resources by authorized users.

• Journal of KIISE:Databases
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• v.35 no.1
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• pp.29-43
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• 2008

Although RDF ontologies might be expressed in XML tree model, existing methods for protection of XML documents are not suitable for securing RDF ontologies. The graph style and inference feature of RDF demands a new security model development. Driven by this goal, this paper proposes a new query-oriented model for the RDF ontology access control. The proposed model rewrites a user query using a three-layered ontology view. The proposal resolves the problem that the existing approaches should generate inference models depending on inference rules. Accessible ontology concepts and instances which a user can visit are defined as ontology views, and the inference view defined for controling an inference query enables a controlled inference capability for the user. This paper defines the three-layered view and describes algorithms for query rewriting according to the views. An implemented prototype with its system architecture is shown. Finally, the experiment and comparative evaluation result of the proposal and the previous approach is described.

• Asia Marketing Journal
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• v.17 no.1
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• pp.123-148
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• 2015

Built on regulatory focus theory, this article develops a research model proposing the relationship between management controls (outcome, activity and capability), sales employees' prevention and promotion focus and their behavioral responses (feedback seeking from different sources and relationship investment). The model also suggests that salesperson perceived organizational fit (P-O fit) contributes by influencing the situational self-regulatory mechanism based on regulatory fit theory. To analyze the data, a structural equation model procedure using LISREL 8.5 was employed. To access the potential common method bias, the MV" marker method was applied using a scale theoretically unrelated to at least one scale in the analysis as the MV marker. The results showed that the greater the salesperson's perceived activity control system, the greater the extent of employee prevention focus. The findings also showed that output control and capability control system are positively related to the promotion focus of salespeople. Salespeople's prevention focus relates negatively to the relational investment and positively to organization feedback seeking. The results indicate that salespeople who have promotion focus exhibit the predicted positive influence on their relationship investment. A significant contribution of this research framework is suggesting salesperson regulatory focus as a mediator and its' effects on different types of sales-related behaviors. The author suggests that the motivational orientations of salespeople play key roles in shaping feedback seeking behaviors from different sources; broadly, that employees with a promotion focus will be more sensitive to customers' feedback, and employees with a prevention focus will seek more feedback from the organization. Furthermore, salespeople with a promotion focus will invest more resources to build relationships with customers than salespeople with a prevention focus. This research also explains the moderating role of person-organization fit on the effect of salespeople's regulatory focus and behavioral responses based on regulatory fit theory

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1162-1169
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• 2012

One of the important operational requirements for mission critical Ethernet networked system is having the fault tolerant capability. Such capability can be obtained by equipping multiport Network Interface Card (NIC) in each node in the system. Conventional NIC uses two or more Media Access Controls (MACs) and a co-processor for the MAC switching whenever an active port fails. Since firmware is needed for the co-processor, longer fail-over switching and degraded throughput can be generally expected. Furthermore the system upgrading requiring the firmware revision in each tactical node demands high cost. In this paper we propose a novel single MAC based NIC that does not use a co-processor, but just use general discrete building blocks such as MAC chip and switching chip, which results in better performances than conventional method. Experimental results validate our scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.549-556
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• 2011

In this paper, high performance radio buoy system for inshore and deep sea fishery is proposed and implemented. Binary FSK modulation technique is used for real-time communication & control between buoys and buoy finder, and optimum access protocol is adopted for minimizing the power consumption of radio buoy system. Using the GPS and sensor techniques, location and environments of radio buoy can be accurately monitored and traced by the mother ship. Developed buoy system with 10 W transmitting power can cover over 120km coastal range and operate more than 73 days of battery life. Proposed digital coding methods can also assure high security from burglary and loss.