• Journal of Korea Multimedia Society
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• v.9 no.2
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• pp.189-196
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• 2006

This paper proposes a priority based AOI management model as a method to effectively process message traffic for collaboration in virtual environments. Where message traffic reaches the maximum capacity of the message replay server in DVE, some of the events might be delayed to be updated at the remote clients. Because existing AOI models depend only on the occurrence time of events, they have a problem that more important events in the context might be processed later than less serious ones. Close Interactions with other participants are relatively more important than simple events which happen at a distance from the participant. This study classifies the priorities of events according to the degree of interest, and proposes a method to reduce processing delay time of events highly interested by a user. The proposed model offers a way to effectively utilize limited capacity of a server using a priority queue mechanism, which is able to handle different kinds of events. To prevent from starvation of simple events and to give fairness to the proposed algorithm, event occurrence time is also considered as well as degree of interest when processing events.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.3
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• pp.517-524
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• 2018

This Paper presents the real time things control method through Web browser that has no limited by time and place. To design and realize the system that not only makes it possible to communicate with other protocols but also reinforces the advantages of each protocol, the real time communication environment, based on the WebSocket technology of HTML5 whose international standardization has recently been completed, is realized. Also, the message communication environment in the low electricity and limited communication environment is realized using MQTT(Message Queue Telemetry Transport) protocol which is in the spotlight as the optimum protocol in the IoT environment. And by designing intuitive and simple hardware and realizing the responsive web interface which is not limited by the user's contact devices, the interactive system in which the user receives real time data from the hardware and reversely the user controls the things is designed and realized.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.485-487
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• 2017

With the growth of the IoT, security is a growing concern. Things the risk of IoT security has been constantly raised, and there have been many cases of hacking. As a result, there is a growing concern and scale about security, but there is a lack of interest and research on the message protocols between Iot devices. With the development of the IoT, the importance of low-power, lightweight and accurate message delivery will become more important and more advanced message protocols will be needed. In this paper, it is aimed to construct the system for communication between client and server of MQTT and CoAP with Confirmative option, which are most used among IoT message protocols and compare the message reliability of each communication protocol to check efficiency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.533-535
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• 2017

MQTT provides three QoS levels on top of the TCP/IP layer to ensure message delivery reliability. However, in an environment where messages are concurrently transmitted and received in a node, messages are lost due to the delivery method for QoS level. In this paper, it construct an experimental environment in which MQTT generates concurrently messages, and confirm the message reliability according to QoS level. Therefore, we analyze the message reception ratio on the subscriber side by changing number of publisher and transmission cycle of message. Experimental results show that the message reception ratio of 1 and 2 except QoS level 0 decreases as the number of publisher increases or the message transmission cycle increases.

• Journal of Korea Multimedia Society
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• v.15 no.8
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• pp.1038-1047
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• 2012

The SIP(Session Initation Protocol) is an application layer protocol that is used to establish, release, and change the call session of the IP telephony. In the SIP signalling networks, when the number of the UA(User Agent) requested the call session increase, the number of messages to be processed by SIP proxy server increase. It often will be caused the overload of the SIP proxy server. In this paper, we proposed the overload control method with a normal queue and a delay queue in the SIP proxy server. When it is estimated the overload of the server by the excess of the high threshold in the normal queue, new INVITE messages will be put into the delay queue to reduce the load of the server. It results in some delay of the call session from the INVITE message. Subsequently when the number of messages in the normal queue is reduced below the low threshold, the INVITE messages in the delay queue is processed. The simulation results showed that the number of the retransmission messages by our proposed method was 45% less than the one by the method with single queue. The results also showed that the average call success rate by the proposed method was 2% higher than the one by the method with single queue.

• Review of KIISC
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• v.24 no.6
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• pp.37-47
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• 2014

최근 정보통신기술 분야의 최대 관심사는 모든 사물간의 통신이 이루어지는 Internet Of Things, 더 나아가 Internet Of Everythings 분야이다. 이러한 흐름에 발맞추어 사물과 관련된 다양한 기술이 점진적으로 발달하였고, 누구나 쉽게 사물간의 인터넷 결합을 이용하여 Ubiquitous 시대를 맞이해 인간의 편리성을 위한 다양한 서비스를 이용할 수 있을 것으로 예상된다. 앞으로의 우리 생활에 점차 밀접한 관계를 맺음에 따라 다양한 기술들이 개발 및 접목될 것으로 예상이 된다. 본 논문에서는 Internet Of Things의 시대가 발전함에 따라 이에 관련된 현재 활용되는 기술 중 MQTT(Message Queue Telemetry Transport)에 대해 기술 할 것이며 이 기술과 관련된 다양한 정보 침해에 대한 향후대책 및 대응방안에 대해 기술한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.829-832
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• 2012

MQTT(Message Queue Telemetry Transport) 는 IBM 에서 발표한 오픈 프로토콜이다. MQTT 는 메시지 전달의 신뢰성 보장을 위하여 3 단계의 QoS 를 지원한다. 본 논문에서는 실제 유/무선 네트워크 환경에서의 Publish 클라이언트에서 Broker 서버를 지나, Subscribe 클라이언트에 이르기까지 메시지 전달에 대하여 분석한다. 메시지는 MQTT 의 3 단계의 QoS 레벨과 페이로드 크기를 다양하게 전달하여 패킷을 캡쳐하고, 메시지에 대한 종단 간 지연과 메시지 손실에 대한 분석과 상관관계의 결과를 제시한다.

• Proceedings of the Korea Society for Simulation Conference
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• 1994.10a
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• pp.32-32
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• 1994

In this example, a message passing based multicomputer system with general interdonnedtion network is considered. After multicomputer systems are developed with morm-hole routing network, topologies of interconecting network are not major considertion for process management and resource sharing. Tehre is an independeent operating system kernel oneach node. It communicates with other kernels using message passingmechanism. Based on this architecture, the problem is how mech does performance degradation will occur in the case of processor sharing on multicomputer systems. Processor sharing between application programs is veryimprotant decision on system performance. In almost cases, application programs running on massively parallel computer systems are not so much user-interactive. Thus, the main performance index is system throughput. Each application program has various communication patterns. and the sharing of processors causes serious performance degradation in hte worst case such that one processor is shared by two processes and another processes are waiting the messages from those processes. As a result, considering this problem is improtant since it gives the reason whether the system allows processor sharingor not. Input data has many parameters in this simulation . It contains the number of threads per task , communication patterns between threads, data generation and also defects in random inupt data. Many parallel aplication programs has its specific communication patterns, and there are computation and communication phases. Therefore, this phase informatin cannot be obtained random input data. If we get trace data from some real applications. we can simulate the problem more realistic . On the other hand, simualtion results will be waseteful unless sufficient trace data with varisous communication patterns is gathered. In this project , random input data are used for simulation . Only controllable data are the number of threads of each task and mapping strategy. First, each task runs independently. After that , each task shres one and more processors with other tasks. As more processors are shared , there will be performance degradation . Form this degradation rate , we can know the overhead of processor sharing . Process scheduling policy can affects the results of simulation . For process scheduling, priority queue and FIFO queue are implemented to support round-robin scheduling and priority scheduling.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.5
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• pp.903-909
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• 2010

ADAS is the air defense control system performing air surveillance and identification of ROK and near air. This system is self-developed by Air Force, currently operated successfully as the alternative system of MCRC. ADAS processes converting and combining transferred the real time radar data detected by radars. additionally, it displays significant radar data as producing in tracks. Then, it uses the message queue for IPC(Inter Process Communication). the various tactical data processed in the server is ultimately send to the network management process through the message queue for transmitting to the weapon director console. the weapon director receives this transmitted tactical data through the console to execute air defense operations. However, there is a problem that data packet is delayed or lost since the weapon Director does not receive as the amount of tactical data from the server overflowed with air tracks and missions increased. This paper improved the algorism to display and transmit the various tactical data processed from ADAS server to numbers of the weapon director console in the real time without any delay or lost. Improved the algorism, established at exercise, the development server in the real operation network and the weapon director console, is proved by comparing the number of sending tactical data packets in the server and receiving packets in the weapon director.

• Journal of KIISE:Information Networking
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• v.27 no.1
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• pp.39-47
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• 2000

This paper is to propose an efficient and reliable control procedure of Base Station Controller of mobile communication system for bulk input messages which was delivered instantaneously. We divided the input messages that are processed by the base station controller of the mobile communication system into two things ; they are messages related to call connection and o&m(operation and maintenance). In addition, we analyzed the properties of the input messages and then performed computer simulation on each input message by using M/M/1/K queueing model in term of the following viewpoints : the loss probability of input messages, the average queue length, the utilization of process controller(server),the average waiting time in queue. And we compared the performance of the two input messages in the overload controlling which was caused by the congested input messages.