• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.9
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• pp.55-65
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• 2004

ATM was recommended by the ITU and ATM Forum as a means of transportation for B-ISDN. At this time, due to the comprehensive mature of ATM protocol, ATM has been adapted as the backbone system for carrying Internet traffi $c^{[1,2,3,4]}$. But major conceptsregarding the ATN protocol will be used on future technology. This paper presents preventive congestion control mechanisms for detecting HTR(Hard-To Reach) code in ATM systems, in particular for an improved HTR call registration method using network signaling information will discussed. In high speed circuit switching system environments, a fast HTR control mechanism is necessary. We present research results for improving HTR call registration and control methods using network signaling information and fuzzy control mechanisms. We concluded that it showed fast congestion avoidance mechanisms with a fewer system load maximized the efficiency of network resources by restricting ineffective machine attempts.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8A
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• pp.618-624
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• 2009

In the evolution from wireless sensor networks(WSNs) to ubiquitous sensor networks(USNs), technologies that can support intensive data-traffic loads, large number of users, improved interoperability, and extreme longevity are required. Therefore, efficient communication time coordination control and low power consumption becomes one of the most important design goals for USN MAC protocols. So far several time division multiplexed (TDM) MAC protocols have been proposed. However, since the pros and cons of existing protocols are not easy to analyze, it becomes a challenging task to design improved TOM MAC protocols. Based on this objective, this paper provides a novel protocol analysis along with a message complexity derivation and comparison of the existing TDM MAC protocols.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.11
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• pp.12-19
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• 2015

In network-centric warfare, the communication network has played a significant role in defeating an enemy. Especially, the urgent and important data should be preferentially delivered in time. Thus, we proposed a priority MAC protocol based on CSMA/CA with Binary Exponential Back-off for tactical wireless networks. This MAC protocol suggested a PCW(Prioritized Contention Window) with differentiated back-off time by priority and a RBR(Repetitive Back-off Reset) to reset the remaining back-off time. The results showed that this proposed MAC has higher performance than those of DCF(Distributed Coordination Function) in the transmission success rate and the number of control packet transmission by reducing the packet collision. Thus, it produced more effective power consumption. In comparison with DCF, this proposed protocol is more suitable in high-traffic network.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.1
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• pp.29-43
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• 2019

In recent years, as the network traffic in the WSN(Wireless Sensor Network) has been increased by the growing number of IoT wireless devices, SDWSN(Software-Defined Wireless Sensor Network) and its security that aims a secure SDN(Software-Defined Networking) for efficiently managing network resources in WSN have received much attention. In this paper, we study on how to efficiently and securely design a PUF(Physical Unclonable Function)-assisted group key distribution scheme for the SDWSN environment. Recently, Huang et al. have designed a group key distribution scheme using the strengths of SDN and the physical security features of PUF. However, we observe that Huang et al.'s scheme has weak points that it does not only lack of authentication for the auxiliary controller but also it maintains the redundant synchronization information. In this paper, we securely design an authentication process of the auxiliary controller and improve the vulnerabilities of Huang et al.'s scheme by adding counter strings and random information but deleting the redundant synchronization information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1450-1458
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• 2011

The HPcN (Hybrid & high Performance Convergence Network) in research networks means environment which can provide both computing resource such as supercomputer, cluster and network resource to application researchers in the field of medical, bio, aerospace and e-science. The most representative research network in Korea, KREONET has been developing following technologies through the HERO (Hybrid Networking project for research oriented infrastructure) from 200S. First, we have constructed and deployed a control plane technology which can provide a connection oriented network dynamically. Second, the integrated resource management system technology has been developing for reservation and allocation of both computing and network resources, whenever users want to utilize them. In this paper, a testbed network is presented, which is possible to reserve and allocate network resource using the integrated resource management system. We reserve network resource through GNSI (Grid Network Service Interface) messages between GRS (Global Resource Scheduler) and NRM (Network Resource Manager) and allocate network resource through GUNI (Grid User Network Interface) messages between the NRM (network resource manager) and routers, based on reservation information provided from a user on the web portal. It is confirmed that GUNI interface messages are delivered from the NRM to each router at the starting of reservation time and traffic is transmitted through LSP allocated by the NRM.

• 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.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.691-700
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• 2003

Due to the fast development of wire&wireless internet and computer hardware, more and more internet services are being developed, such as Internet broadcast, VoD (Video On Demand), etc. So QoS (Qualify of Service) is essentially needed to guarantee the quality of these services. Traditional Internet is Best-Effort service in which all packets are transported in FIFO (First In First Out) style. However, FIFO is not suitable to guarantee the quality of some services, so more research in QoS router and QoS protocol are needed. Researched QoS router and protocol are high cost and inefficient because the existing infra is not used. To solve this problem, a new QoS control method, named Network Adaptive QoS, is introduced and applied to client/server-based streaming systems. Based on network bandwidth monitoring mechanism, network adaptive QoS control method can be used in wire&wireless networks to support QoS in real-time streaming system. In order to reduce application cost, the existing streaming service is used in NAQoS. A new module is integrated into the existing server and client. So the router and network line are not changed. By simulation in heavy traffic network conditions, we proved that stream cannot be seamless without network adaptive QoS method.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.865-872
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• 2017

Recently, in response to the Internet age, the demand for hardware devices has been increasing, centering on the rapidly growing smart home field, due to the growth and management of sensor and control technology, mobile application, network traffic, big data management and cloud computing. In order to maintain the sustainable development of the hardware system, it is necessary to update the system, and the hardware device is absolutely necessary in real time processing of complex data (voice, image, etc.) as well as data collection. In this paper, we propose a method to simplify the control and communication method by integrating the hardware devices in two operating systems in a unified structure to solve the simultaneous control and communication method of hardware under different operating systems. The performance evaluation results of the proposed integrated hardware and the cloud control system connected to the cloud server are described and the main directions to be studied in the field of internet smart home are described.

• Journal of Korea Multimedia Society
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• v.10 no.4
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• pp.462-469
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• 2007

ATM protocol has the techniques such as cell discarding priority, traffic shaping and traffic policing. ATM based MPLS(Multiprotocol Label Switching) is discussed for its provisioning QoS commitment capabilities, traffic engineering and smooth migration for BcN using conventional ATM infra in Korea. This paper proposes preventive congestion control mechanism for detecting HTR(Hard To Reach) LSP(Label Switched Path) in ATM based MPLS systems. In particular, we decide HTR LSP using real time signaling information(etc., PTI,AIS/RDI) for applying HTR concept in circuit switching to ATM based MPLS systems and use those session gap and percentage based control algorithm that were used in conventional PSTN call controls. We concluded that it maximized the efficiency of network resources by restricting ineffective machine attempts. Proposed control can handle 208% call processing and more than 147% success call, than those without control. It can handle 187% BHCA(Busy Hour Call Attempts) with 100 times less than use of exchange memory.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.119-128
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• 2003

The rapid increase of Internet users, diversity of application services, high speed data transmission, and extension of application areas have resulted in exponential growth of Internet traffic. In order to satisfy the increasing demand of bandwidth, the MPλS protocol, which is based on MPLS for efficient integration of WDM and IP protocols, has been suggested by IETF. In this paper, we present an MPλS simulator which enables to simulate various MPλS function such as optical crossconnect (OXC), multi-wavelength links, routing and wavelength assignment(RWA), and MPλS signaling and control. The simulator is developed based on the ns-2, an widely used multi-protocol network simulator. The function of the simulator is validated by running many simulation based on various scenarios and performance measures such as throughput and blocking probability. The simulator could be widely utilized for validation of proposed protocols before developing real optical network systems.