• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.1B
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• pp.45-54
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• 2003

In the Protocol-Independent Multicast Sparse Mode(PIM-SM), we need a careful selection scheme for the Rendezvous Point(RP) which influences much on the QoS due to the delay among multicast group members and packet loss The QoS based RP selection schemes choose RPs which satisfy the restriction conditions such as bandwidth, delay, and other QoS parameters In this paper, we propose a new RP selection scheme which is a variation of the group-based RP selection scheme The new algorithm, MCT(Maximum Cross Tree), is implemented by taking advantages of the topology-based selection scheme and the group-based selection scheme as well In order to verify the proposed algorithm, we first measure the multicast traffic data of the Virtual Conference System implemented on the IPv6 network via KOREN, then expand the results to two types of network models and analyze the performance by computer simulation.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.415-420
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• 2013

U-WHS refers to a means of remote health monitoring service to combine fitness with wellbing. U-WHS is a system which can measure and manage biometric information of patients without any limitation on time and space. In this paper, we performed in order to look into the influence that the encryption module influences on the communication evaluation in the biometric information transmission gone to the smart mobile device and Hospital Information System.In the case of the U-WHS model, the client used the Objective-c programming language for software development of iOS Xcode environment and SEED and HIGHT encryption module was applied. In the case of HIS, the MySQL which is the Websocket API of the HTML5 and relational database management system for the client and inter-server communication was applied. Therefore, in WIFI communication environment, by using wireshark, data transfer rate of the biometric information, delay and loss rate was checked for the evaluation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4B
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• pp.153-161
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• 2005

In a multi-channel network based of wavelength division multiplexing (WDM) technology, an efficient protocol is needed in order for the transmitter and receiver to be tuned to the same wavelength during message transmission time. This paper proposes a priority-based reservation protocol that can efficiently support variable-length messages that require different QoS requirements. In this proposed protocol, high-priority nodes can reserve the data channel before low-priority nodes. However, once a node reserves a data channel successfully, it can persistently use the reserved channel till message transmission is finished regardless of the priority of the node. Moreover, the protocol can operate independently of the number of nodes, and any new node can join the network anytime without requiring network re-initialization. The protocol is analyzed with a finite population model and the throughput-delay characteristics are investigated as performance measures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5B
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• pp.455-462
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• 2009

In this paper, we propose a buffer management scheme for decreasing the packet loss due to buffer overflow and improving the packet fairness between nodes in IEEE 802.11 based multi-hop mesh networks. In the proposed scheme, each mesh router that is an intermediate node receives fairly packet sent from neighboring mesh routers and mobile nodes, and it improves the reception ratio of multi-hop traffic of neighboring mesh routers. Therefore, the proposed scheme can reduce transmission delay and energy consumption. In order to improving the packet loss and the packet fairness, the proposed scheme uses the modified RTS/CTS under the IEEE 802.11 MAC protocol and reduces the packet loss by recognizing the packet size to send to the destination in advance. By using the simulation, we evaluated the proposed scheme in terms of the packet loss ratio and the number of received packet in each mesh router, and compare it to a traditional scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.2064-2072
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• 2015

To improve performance, most of Web Services produce and manage User Access Logs. Through the Access Logs, the record provides information about time when the most traffic happens and logs and which resource is mostly used. Then, the log can be used to analyze. However, in case of increasing high traffics of Web Services at the specific time, the performance of Web Service leads to deterioration because the number of processing User Access Logs is increasing rapidly. To solve this problem, we should improve the system performance, or tuning is needed, but it makes a problem cost a lot of money. Also, after it happens, it is not necessary to build such system by spending extra money. Therefore, this paper described the effective Web Service's performance as using improved User Access Log performance. Also, to process the newest data in bulk, this paper includes a method applying some parts of NoSQL using Redis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6B
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• pp.608-617
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• 2011

ubiquitous network management system (u-NMS) is the network management system based on smartphone which are recently of wide use. The purpose of the u-NMS is to provide convenience for network administrator utilizing the mobility of smartphone and to manage the network efficiently. This paper proposes the smart NMS agent and the mobility management server (MMS). The smart NMS agent enables to use the monitoring web server and remote control application on the smartphone in wireless network. The MMS is developed to reduce the problems such as handover latency and packet loss, which can be taken place in wireless network. The network manager can monitor traffic in real time through the smart NMS agent and remotely control the network efficiently when sudden failures happen in the u-NMS. In this paper, performance evaluation is carried out with our test-bed system implemented. We focus on the measurement of the MMS performance. When the MMS is compared to previous mobility management protocol, our mobility management server reduces the average latency up to 65% in initial access, handover latency and processing delay to the network management center.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.886-889
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• 2010

Power consumption measurement in sensor network is difficult to proceed by survey in real field. Thus, through simulation, the power consumption is estimated and replacement time of nodes are decided. A simulation tool simulates various facts such as power consumption, packet transmission traffic, network topology and etc. In this paper, it suggests sensor node power model to simulate power consumption which has large importance among simulation facts in sensor network. This model omits calculating expressions that the data originally surveyed can substitute with, according to power consumption property of each functions in sensor node in order to minimize calculations in simulation. In this case accuracy of power consumption estimation will be reduced, but can simulate it faster due to reduced calculation. Suggested model is fitted to analyze power consumption difference between two or more sensor network algorithms with rapid simulation speed rather than accurate simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1486-1491
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• 2017

In this paper, we propose a private multimedia caching scheme based on wireless local area network (WLAN) to improve the quality of service for high capacity and high quality multimedia streaming services which are recently increasing and to reduce the traffic load of core networks. The proposed caching scheme stores multimedia in the storage device mounted on WLAN APs and provides streaming services on its own without Internet connection in accordance with the request from clients. We have implemented a test network based on real commercial networks and measured the performance of the proposed caching scheme in terms of frames per second (FPS) and buffering time. According to the performance measurement results, the proposed caching scheme can reduce the average buffering time by 73.3% compared to the conventional streaming scheme. In addition, the proposed caching scheme can also improve the average FPS by 71.3% compared to the conventional streaming scheme.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.227-234
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• 2002

MPLS which integrates routing of layer 3 and switching of layer 2, enables support for fast forwarding, traffic engineering and virtual private network services. GSMP is open interface protocol between a label switch and a controller, and it provides connection, configuration, event, performance management and synchronization. In the GSMP open interface, the functions of network management can be located either in the controller or in the label switch. To simplify the label switch and enhance the efficiency of resources, we adopt the network management model, in which the SNMP agent is located in the controller and is interworked with the GSMP. We presented the interworking scenrios between the GSMP and the network management of MPLS. We implemented the controller to verify the realization of our adopted network management model, and measured the connection setup delay of the provisioned connection.

• The Korean Journal of Applied Statistics
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• v.26 no.2
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• pp.291-305
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• 2013

Collective traffic data (BPS, PPS etc.) for detection against the distributed denial of service attack on network is the time sequencing big data. The algorithm to detect the change point in the big data should be accurate and exceed in detection time and detection capability. In this work, the sliding window and discretization method is used to detect the change point in the big data, and propose five nonparametric test statistics using empirical distribution functions and ranks. With various distribution functions and their parameters, the detection time and capability including the detection delay time and the detection ratio for five test methods are explored and discussed via monte carlo simulation and illustrative examples.