• The KIPS Transactions:PartB
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• v.8B no.6
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• pp.641-650
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• 2001

Jini architecture's Network Plug and Work provides simple and flexible network environment for distributed applications. Through the Jini technology, facilities for dynamically registering and locating mobile agent services can be easily supported, as well as the services useful for activities of mobile agents can be dynamically supported. In this paper, we describe a Jini-based mobile agent system named JMoblet, which provides the basic functions of a mobile agent system such as creation, control, transfer, location and communication among agents. To increase the reliability of the system, it also provides exception handling and persistence of the mobile agent systems for reliability.

• The Transactions of the Korea Information Processing Society
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• v.4 no.2
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• pp.363-376
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• 1997

In this paper, we present a hardware architecture and a sofrware architecture for cimputer based teleconferencing systems.And also we analyse stream adtivation mechanisms for them form the viewpoint of delay. MuX that is a multimedia I/O server provides various processing elements for data I/O, synchronization, interleaving and mixing.We describe methods to build teleconferencing systems with the elements and compares the technique using master click with the techniquie using self clock.In the plase of dta input.the technique using self click is berrer than the technique using master clock.When we generate interleved stream from audio and video stream and activate channel objects by periodic audio stream as activation clock, dealy from imput audio stream to imterleved stream is reduced but delay for video stream is not reduced as much as in the case of audio stream.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8B
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• pp.1371-1382
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• 2000

IMT-2000 system is the third generation mobile communication system which aims at mobile multimedia services with global roaming. Like 2nd generation system, the IMT-2000 system is also under strong influence of interferences among active subscribers in the multiple access environment. That is, in multiple access environment, signals from one subscriber could interfere with others in the same cell or in the neighboring cells. The interference control in the IMT-2000 systems is much more difficult then the interference control in the 2ndgeneration CDMA cellular systems, since the transmitted power of a subcriber might be different that of others in the IMT-2000 system. In this paper, a parallel interference cancellation with traffic discrimination is proposed which can effectively cancel interferences by grouping the subscribers into several equi-power classes. As a conclusion, simulation results show that the proposed method outperforms the conventional partial PIC scheme in several aspects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.27-34
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• 2010

As VoIP systems move to wireless environments with much higher average packet loss rates than wired networks, it becomes less possible for the network to assure a reasonable QoS. So, real-time quality monitoring for mobile VoIP applications is an important issue to be explored. In this paper, we explore perceptual quality dependency on two parameters: the burst loss rate and average burst length. Also, we propose a simple 'moving average' approach with $\alpha$ aiming to measure those parameters on real-time basis. In order to find how accurately the two parameters measured estimate the real perceptual quality, we compare actual measured PESQ scores with estimated value by matching the measured quality metric to the trained MOS table. Finally, we propose the quality-based accounting system, which can set obvious continuities between quality and billing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6B
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• pp.403-410
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• 2008

In this paper, we investigate the performance of MMR system in Non-transparent mode. The IEEE 802.16j MMR system has two node of operation, Single-frame (in band) and Multi-frame (out band) mode. In the analysis, we assume that channel interference between MR-BS and RS, or between RSs anywhere in the given area is ignored. The performance is presented in terms of the delay and the frame efficiency by varying number of RS and BS coverage to RS coverage ratio and the maximum coverage area of a BS by varying traffic density. Analytical results show that the Single-frame is more efficient than Multi-frame in frame efficiency and coverage extension.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.137-148
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• 2007

Due to the advance of technology, the technology of various media is rapidly converged into digital technology. However, the conversion into digital radio is not achieved in korea yet. This paper is to suggest the best method of digital conversion of radio in korea by examining some conversion examples in foreign countries. In addition, the survey results on radio audience attitude is analysed by 2,000 audience samples in Korea based on the literature analysis. Radio is the unique media which have the strengths such as mobility, individuality, presence, broad coverage and instant. Most of all, radio cannot help keeping continuously the public broadcasting service in the future. So, the conversion into digital radio is crucial to sustain the competitiveness in digital media environment. This paper suggested that the digital conversion of radio broadcasting needs DRM transmission and should pursuit the policy which is distinguished between a AM and a standard FM, and between domestic broadcast and an international broadcast. Additionally, this paper proposed that we need to develop the multiple device for receiving of signal and the setting of standard technology.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.45-52
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• 2005

This paper proposes low latency handover procedure for seamless connectivity and QoS support between wired (e.g. Ethernet) and wireless (e.g. WLAN, WiBro(802.16-compatible), CDMA) networks by the mobile-assisted and server-initiated handover strategy. It is assumed that the server decides the best target network considering network status and user preferences. In this procedure, a mobile terminal associates with the wireless link decided at the server in advance and receives CoA as well. When handover occurs without the prediction in wired networks, the server performs fast binding update using physical handover trigger through the MIH (media independent handover) function. As a result, a mobile terminal does not need to perform L2 and L3 handover during handover so that this procedure decreases handover latency and loss.

• Journal of Digital Convergence
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• v.17 no.12
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• pp.219-228
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• 2019

Thanks to the development of information technology and the vitalization of smart services, the Internet of Things (IoT) technology, in which various smart devices are connected to the network, has been continuously developed. In the legacy IoT architecture, data processing has been centralized based on cloud computing, but there are concerns about a single point of failure, end-to-end transmission delay, and security. To solve these problems, it is necessary to apply decentralized blockchain technology to the IoT. However, it is hard for the IoT devices with limited computing power to mine blocks, which consumes a great amount of computing resources. To overcome this difficulty, this paper proposes an IoT architecture based on the edge computing technology that can apply blockchain technology to IoT devices, which lack computing resources. This paper also presents an operaional procedure of blockchain in the edge computing-based IoT architecture.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.8
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• pp.30-41
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• 2001

In this paper, the architecture of Dynamic GSMP V3(General Switch Management Protocol Version 3), an open interface protocol with resource management functions for efficient IP service on ATM over MPLS, is proposed and implemented in hardware. And we compare and analyze the proposed GSMP with the GSMP under standardization process in terms of CLR (Cell Loss Rate). We design the Slave block of the Dynamic GSMP V3 using SAM-SUNG SoG $0.5{\mu}m$ process, which performs functions for switch connection control in the ATM Switch. In order to compare difference performanaces between the proposed method and the conventional one, we conducts simulations using the minimum buffer search algorithm with random cell generation. The exponential results show that the proposed method leads to performance enhancement in CLR.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.9
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• pp.20-29
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• 2008

WLP(WiMedia Logical link control Protocol) is a protocol to support IP services on the WiMedia UWB platform. It defines that DRP needs to be employed using TSPEC parameters when the packets from upper layer transmit with QoS. However, there is no appropriate means to provide QoS when the TSPEC of the traffic is unknown. In this paper, we propose TSPEC estimation scheme to provide QoS for such unknown applications by monitoring the traffic in realtime. Also, the scheme to estimate the effective TSPEC is proposed that compensate the packet losses in the wireless environment to provide the required QoS. The performances of the proposed TSPEC estimation schemes are evaluate by simulation assuming random wireless packet loss and 1mm-ACK mechanism.