• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.9
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• pp.809-818
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• 1991

We investigate the onsiderations of design issues for a bradband ATM network. Three kimds of network design requirement are considered ; user grade-of-service(GOS) requirements. Network manager requirements, and system designer requirements. In this work, e are focusing on the balancing problems among performance measures. We suggest that design parameters for a bradband ATM echange would be tuned within the acceptable sets by a layering concept on the peformance objectives.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.160-162
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• 2007

The systems for assisted living and convenience of user real-time requirement in data communication among devices. therefore, it system was requirement to implementation of the hardware which guarantees the real-time to load the high-performance processor with suitable Operation System. This paper apply to operated intelligence robot in USN(Ubiquitous Sensor Network) environment, particularly, it is architecture research for guarantees the real-time of a sink-node that collect various sensor information from sensors and sending to main control unit.

• Journal of the Korea Society of Computer and Information
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• v.20 no.10
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• pp.53-59
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• 2015

In this paper we propose a resource management scheme which allocates hierarchical resources stepwise based on the users' QoS requirement of each service in the macro-femtocell overlaid LTE-Advanced network. Our proposed scheme adjusts the transmission rate to the minimum which guarantees the allowable minimum requirement of delay for each user service. In this way it minimizes the interference on the adjacent channels and it is able to increase the resource utilization efficiency. Simulation results show that our scheme provides better performances than the conventional one in respect of the outage probability and data transmission throughput.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.12
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• pp.1945-1955
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• 1993

Two types of key distribution protocols with user authentication are proposed for PCS(Personal Communication Service) and digital mobile communication systems. In this paper, we investigate the service procedure and security requirement for PCS. also discuss the security problems of KDPs previously proposed for digital mobile communication, and show that Park`s type II among the schemes is easily broken by an impersonation attack. Our proposed I, II are based on the modified cryptosystem of Rabin and ElGamal, and reduce the amount of computation for user authentication. Such a reduction is good solution coped with the limited capability of user terminal on PCS. As a result of making a comparison between our schemes and the previously presented schemes, we can know ours are more secure and efficient for PCS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.391-398
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• 2000

In this paper, MRC(Maximum Ratio Combine) diversity, (23, 12) Golay code, (7, 5) Reed-Solomon code, and (3, 1) majority selection code are employed to improve the performance of DS/CDMA BRSK in Nakagami fading channel. and MRC diversity combined with other coding techniques is suggested, with which, the performance of DS/CDMA BRSK is compared and analyzed. Also, system required Eb/N0 to meet BER=10-5 for multi user data communication is obtained according to each techniques. From the results, when each techniques is employed to DS/CDMA BRSK system. coding employed system shows better performance than diversity employed system. Especially, Golay code shows better performance than oter codes. also MRC diversity is employed, the number of multiple access user to meet data communication requirement of BER=10-5 can accomodate up to 8 users. and when each code is employed, Golay code, majority selection code, and Reed-Solomon code shows the capacity of 14, 12, and 10 user respectively. But MRC diversity combined with coding techniques can reduce restriction of multiple access user. However, it is desirable these combined technique are employed according to service types and requirements provided.

• The KIPS Transactions:PartD
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• v.10D no.2
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• pp.293-300
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• 2003

As Internet has grown rapidly and been more complex by technology in connection with Web and requirement of business, qualify and reliability of Web application are getting important. It is necessary to study about testing method along with design technique specially in Web application. This paper explains automation method of user interface test to make test cases about user input form with HTML pages using by built-in browser objects. Examples shows the possibility of testing automation with Javascript objects get mapped. Overhead of writing Javascript can be reduced by making script generator. Generated test scripts are repeatedly used in regression testing Web-based application.

• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.61-69
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• 2004

The user interface design needs to support the complex interactions between human and computers. It also requires comprehensive knowledges many areas to collect customer's requirements and negotiate with them. The user interface designer needs to be a graphic expert, requirement analyst, system designer, programmer, technical expert, social activity scientist, and so on. Therefore, it is necessary to research on an designing methodology of user interface for satisfying various expertise areas. In the paper, We propose the 4 business event's abstract object visualizing phases such as fold abstract object modeling, task abstract object modeling, transaction abstract object modeling, and form abstract object modeling. As a result, this modeling method allows us to enhance visual cohesion of UI, and help unskilled designer to can develope the higy-qualified user interface.

• Journal of Communications and Networks
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• v.9 no.2
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• pp.112-117
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• 2007

In this paper, we focus on the total transmission power minimization problem for downlink beamforming multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems while ensuring each user's QoS requirement. Although the linear integer programming (LIP) solution we formulate provides the performance upper bound of the margin adaptive (MA) optimization problem, it is hard to be implemented in practice due to its high computational complexity. By regarding each user's equivalent channel gain as approximate independent values and using iterative descent method, we present a heuristic MA resource allocation algorithm. Simulation results show that the proposed algorithm efficiently converges to the local optimum, which is very close to the performance of the optimal LIP solution. Compared with existing space division multiple access (SDMA) OFDM systems with or without adaptive resource allocation, the proposed algorithm achieves significant performance improvement by exploiting the frequency diversity and multi-user diversity in downlink multiple-input single-output (MISO) OFDM systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.2
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• pp.241-243
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• 2016

The recent spread of smart devices has led to creating a variety of services based on the smart device, and the needs for the user-centric services that fit the individual users according to their situations and characteristics are increasing. However, current services can not fulfil the individual requirement of individual user, because these services are intended for unspecified individual. This paper, as a key technology of automatic user-centric service mash-up considering the situation of individual user, investigated the similarity comparison method between the Open API parameters by calculating the amount of mutual information of the parameters extracted from the Open API documents.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1311-1324
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• 2019

In the traditional cellular network communication, the cellular user and the base station exchange information through the uplink channel and downlink channel. Meanwhile, device-to-device (D2D) users access the cellular network by reusing the channel resources of the cellular users. However, when cellular user channel conditions are poor, not only D2D user cannot reuse its channel resources to access the network, but also cellular user's communication needs cannot be met. To solve this problem, we introduced a novelty D2D communication mechanism in the downlink, which D2D transmitter users as half-duplex (HD) relays to assist the downlink transmission of cellular users with reusing corresponding spectrum. The optimization goal of the system is to make the cellular users in the bad channel state meet the minimum transmission rate requirement and at the same time maximize the throughput of the D2D users. In addition, i for the purpose of improving the efficiency of relay transmission, we use two-antenna architecture of D2D relay to enable receive and transmit signals at the same time. Then we optimized power of base station and D2D relay separately with consideration of backhaul interference caused by two-antenna architectures. The simulation results show that the proposed HD relay strategyis superior to existing HD and full-duplex (FD) models in the aspects of system throughput and power efficiency.