• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.83-93
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• 2003

Differentiated service networks, based on bandwidth broker, perform the control and management of QoS provisioning for the QoS guaranteed services, However, the centralized bandwidth broker model has a scalability problem since it has centralized resource management for the admission control function of all call attempts, Therefore, in this paper, we proposea novel adaptive admission control mechanism according to the attempted call status for enhancing the scalability under the centralized bandwidth broker model in IP differentiated service networks, The proposed mechanism decouples the function of admission control from the bandwidth broker, So, the ingress edge node performs the admission control and the bandwidth broker performs the resource management and QoS provisioning, We also introduce an edge-to-edge path concepts and the ingress edge node performs the admission control under the allocated bandwidth to eachpath. The allocated bandwidth per path adaptively varies according to the status of the attempted calls, This mechanism can significantly reduce the number of communication message between the bandwidth broker and each edge node in the network and increase the bandwidth utilization via adaptable resource allocation, In this paper we study the adaptive admission control operation and show the efficient and extensive improvement through the performance evaluation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.130-138
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• 2009

6LoWPAN is IPv6 packets transmission technology at Sensor network over the IEEE 802.15.4 Standard MAC and Physical layer. Adaptation layer between IP layer and MAC layer performs fragmentation and reassembly of packet for transmit IPv6 packets. RFC4944, IETF 6LoWPAN WG standard document define packet fragmentation and reassembly. In this paper, we propose the IRM(Immediate Retransmission Method) and SRM(Selective Retransmission Method) to manage packet fragmentation and reassembly at 6LoWPAN. Each time destination receives a fragmented packet, it sends Ack message to the source node on IRM. However, on SRM, the destination node receives all fragmented packet, it sends Ack message or Nak message to the source node. In this case, Nak message include the dropped packet number. To compare the performance of the proposed schemes, we develop a simulator using C++. The result of simulation shows the proposed schemes provider better performance than RFC4944 standard scheme.

• Journal of KIISE:Information Networking
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• v.29 no.4
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• pp.437-446
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• 2002

In order to reduce the increasing packet loss rates caused by an exponential increase in network traffic, the IETF (Internet Engineering Task Force) is considering the deployment of active queue management techniques such as RED (Random Early Detection). While active queue management in routers and gateways can potentially reduce packet loss rates in the Internet, this paper has demonstrated the inherent weakness of current techniques and shows that they are ineffective in preventing high loss rates. The inherent problem with these queue management algorithms is that they all use static parameter setting. So, in case where these parameters do not match the requirement of the network load, the performance of these algorithms can approach that of a traditional Drop-tail. In this paper, in order to solve this problem, a new active queue management algorithm called ARED (Active RED) is proposed. ARED computes the parameter based on our heuristic method. This algorithm can effectively reduce packet loss while maintaining high link utilizations.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.2917-2924
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• 2012

Four novel metal-organic complexes $[Cd_2(IP)_2(TBZ)_2(H_2O)_2]{\cdot}(H_2O)$ (1), $[Zn_4(IP)_4(TBZ)_4]{\cdot}2(H_2O)$ (2), $[Zn_2(BTC)(TBZ)_2(CO_2H)]$ (3), [Co(PDC)(TBZ)] (4) (where IP = isophthalate; TBZ = thiabendazole; BTC = 1,3,5-benzenetricarboxylate; PDC = pyridine-3,4-dicarboxylate) have been prepared and characterized by IR spectrum, elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. X-ray structure analysis reveals that 1, 2, and 3 are one-dimensional chain polymers, while 4 is a two-dimensional network polymer. The TBZ acts as a typical chelating ligand coordinated to the metal center in all complexes. The 1D chain architecture of 1 is constructed from isophthalates and cadmium atoms. A simultaneous presence of chelating, monodentate and bidentate coordination modes of IP ligands is observed in complex 2. In complex 3, the 16-membered rings are alternately arranged forming an infinite 1D double-chain structure. The 2D skeleton of 4 is formed by cobalt ions as nodes and PDC dianions as spacers, through coordination bonds. The hydrogen bonds and ${\pi}-{\pi}$ stacking play important roles in affecting the final structure where complexes 1 and 3 have 2D supramolecular networks, while complexes 2 and 4 have 3D supramolecular architectures.

• ETRI Journal
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• v.27 no.1
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• pp.22-42
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• 2005

Traditional traffic identification methods based on wellknown port numbers are not appropriate for the identification of new types of Internet applications. This paper proposes a new method to identify current Internet traffic, which is a preliminary but essential step toward traffic characterization. We categorized most current network-based applications into several classes according to their traffic patterns. Then, using this categorization, we developed a flow grouping method that determines the application name of traffic flows. We have incorporated our method into NG-MON, a traffic analysis system, to analyze Internet traffic between our enterprise network and the Internet, and characterized all the traffic according to their application types.

• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.271-280
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• 2010

For the next generation mobile communication system, diverse wireless network techniques such as beyond 3G LTE, WiMAX/WiBro, and next generation WLAN etc. are proceeding to the form integrated into the All-IP core network. According to this development, Beyond 3G integrated into heterogeneous wireless access technologies must support the vertical handover and network to be used of several radio networks. However, unified management of each network is demanded since it is individually serviced. Therefore, in order to solve this problem this study is introducing the theory of Common Radio Resource Management (CRRM) based on Generic Link Layer (GLL). This study designs the structure and functions to support the vertical handover and propose the vertical handover algorithm of which policy-based and MCDM are composed between LTE and WLAN systems using GLL. Finally, simulation results are presented to show the improved performance over the data throughput, handover success rate, the system service cost and handover attempt number.

• Journal of the Korea Society of Computer and Information
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• v.18 no.2
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• pp.77-85
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• 2013

Recently, location information based routing protocol has been studied to estimate end-to-end path in wireless ad-hoc network. This protocol assumes all nodes can get heir location information via GPS devices and floods only limited area with routing message through acquired location information. Therefore, this protocol has advantage that can reduce the number of routing message than the existing IP-based routing protocols. In addition, all nodes enabling this protocol must acquire their own location information to participate in the location-based routing. However, recent because of the miniaturization of sensor node, sensor node without GPS function has been launched. Therefore in case of the sensor node that does not know location information, it is impossible to participate in the ad hoc network configuration and location information based routing. In this paper, a virtual location information based routing scheme is proposed for wireless nodes without GPS function to be able to participate in location information based routing within ad hoc network environments consisting of wireless nodes with GPS function and wireless nodes without GPS function. Therefore, the proposed protocol has the advantage that a wireless node without a GPS function is able to participate in ad hoc network configuration and the location information based routing.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.2 s.3
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• pp.43-54
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• 2003

As the demand for ubiquitous mobile wireless Internet grows, vehicles are receiving a lot of attention as new networking platforms. The demand for 4G all-IP networks encourages vehicle networks to be connected using IPv6. By means of network mobility (NEMO) support, we can connect sensors, controllers, local ,servers as well as passengers' devices of a vehicle to the Internet through a mobile router. The mobile router provides the connectivity to the Internet and mobility transparency for the rest of the mobile nodes of an in-vehicle nv6 network. So, it is .important for the mobile router to assure reliable connection and a sufficient data rate for the group of nodes behind it. To provide reliability, this paper proposes an adaptive multihoming architecture of multiple mobile routers. Proposed architecture makes use of different mobility characteristics of different vehicles. Simulation results with different configurations show that the proposed architecture increases session preservation thus increases reliability and reduces packet loss. We also show that the proposed architecture is adaptive to heterogeneous access environment which provide different access coverage areas and data rates. The result shows that our architecture achieves sufficient data rates as well as session preservation.

• Journal of Biomedical Engineering Research
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• v.18 no.1
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• pp.17-24
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• 1997

We have developed a patient monitoring system including module-based bedside monitors, interbed network, central stations, clinical workstations, and DB servers. A bedside monitor with a color LCD can accommodate up to 3 module cases and 21 different modules. Six different physiological parameters of ECG, respiration, invasive blood pressure, noninvasive blood pressure, body temperature, and arterial pulse oximetry with plethysmoyaph are provided as parameter modules. In a single bedside monitor, modules and a module controller communicate with IMbps data rate through an intrabed network based on RS-485 and HDU protocol. At the same time, it communicates with other bedside monitors and central stations through interbed network based on 1 OMbps Ethernet and TCP/IP protocol. Central stations using 20" color CRT monitors can be connected with many bedside monitors and they display 18 channels of waveforms simultaneously. Clinical workstations are used mainly for the review of patient datE In order to accommodate more advanced data management capabilities such as 24-hour full disclosure, we have developed a relational database server dedicated to the patient monitoring system. Software for bedside monitor, central station, and clinical workstation fully utilizes graphical user interface techniques and all functions are controlled by a rotate/push button on the bedside monitor arid a mouse on the central station and clinical workstation. The entire system satisfies the requirements of AAMI and ANSI standards in terms of electrical safety and performances.nces.

• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.989-995
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• 2017

Distributed Control System (DCS) communication networks, which use Fast Ethernet with redundant networks for the transmission of information, have been installed in digitalized nuclear power plants. Normally, failover tests are performed to verify the reliability of redundant networks during design and manufacturing phases; however, systematic integrity tests of DCS networks cannot be fully performed during these phases because all relevant equipment is not installed completely during these two phases. In additions, practical verification tests are insufficient, and there is a need to test the actual failover function of DCS redundant networks in the target environment. The purpose of this study is to verify that the failover functions works correctly in certain abnormal conditions during installation and commissioning phase and identify the influence of network failover on the entire DCS. To quantify the effects of network failover in the DCS, the packets (Protocol Data Units) must be collected and resource usage of the system has to be monitored and analyzed. This study introduces the use of a new methodology for verification of DCS network failover during the installation and commissioning phases. This study is expected to provide insight into verification methodology and the failover effects from DCS redundant networks. It also provides test results of network performance from DCS network failover in digitalized domestic nuclear power plants (NPPs).