• The KIPS Transactions:PartC
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• v.12C no.3 s.99
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• pp.457-464
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• 2005

This paper describes an Adaptive Context-aware Service (ACS) using Model Driven Architecture (MDA)-based Service Creation Environment (SCE) on PARLAY X based service delivery platform in ubiquitous computing environments. It can be expected that both the context-awareness and adaptation in ubiquitous computing environments will be deployed. But the existing context-aware middleware lacks in considering adaptation. Therefore, the object of this paper is to support the architecture and the Application Programming Interface (API) of the network service for both the context-awareness and adaptation in ubiquitous computing environment. ACS is to provide users with the adaptive network service to the changing context constraints as well as detecting the changing context. For instance, ACS can provide users with QoS in network according to the detected context, after detecting the context such as location and speed. The architecture of ACS is comprised of a Service Creation Environment (SCE), Adaptive Context Broker and PARLAY gateway. SCE is to use Context-based Constraint Language (CCL) for an expression of context-awareness and adaptation. Adaptive Context Broker is to make a role of the broker between SCE and PARLAY G/W. PARLAY G/W is to support API for PARLAY X-based service delivery platform.

• Proceedings of the Korea Database Society Conference
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• 1998.09a
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• pp.475-505
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• 1998

With rapid progresses in information technologies, managing enterprise network resources as a whole becomes more important. Telecommunication Management Network (TMN) has been used to integrate network elements. TMN is complex to develop and manage because it has a centralized management service. Common Object Request Broker Architecture (CORBA) can overcome this complexity by the use of transparent distributed object processing mechanism. Therefore, the main objective of this paper is to integrate TMN service with CORBA. A network management repository is built for this integration. In addition, a prototype that can partially support network management service is implemented to illustrate the usefulness of this repository.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1320-1326
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• 2017

Recently, IoT has been studying a lightweight protocol to satisfy device communication in a limited network environment. MQTT is a typical lightweight protocol. It supports small fixed headers to minimize overhead, and adopts publish/subscribe structure to guarantee real-time performance. However, MQTT does not support prioritization of important data and can not provide QoS in a specific IoT service. In this paper, we propose a message processing method to consider the priority of various IoT services in MQTT. In the proposed method, the priority flag is added to the fixed header of the MQTT in the node to transmit the message, and the broker confirms the priority of the corresponding message and processes it preferentially. Through experiment and evaluation, we confirmed the reduction of end-to-end delay between nodes according to priority.

• Journal of Communications and Networks
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• v.7 no.2
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• pp.207-221
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• 2005

The proliferation of wireless local area networks (WLANs) offering high data rate in hot spot area have spurred the demand for possible WLANs and third-generation (3G) cellular network integration solutions as the initiative step towards 4G systems. This paper provides a novel architecture for seamless location-aware integration of WLANs into 3G cellular networks and also an analysis for the efficient handover techniques. We introduce location as a key context in secure roaming mechanism for context-aware interworking in 4G systems. The fast secure roaming with location-aware authentication is implemented at an entity called location-aware service (LAS) broker that utilizes the concepts of direction of user and pre-warming zone. The location-ware interworking architecture supports seamless roaming services among heterogeneous wireless networks including WLANs, wireless metropolitan area networks (WMANs), and 3G cellular networks. This paper also includes a description of procedures needed to implement efficient mobility and location management. We show how the LAS broker with pre-warming and context transfer can obtain significant lower latency in the vertical handover.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11B
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• pp.956-966
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• 2004

Nowadays, NGN(Next Generation Network) is evolving into network with packet based QoS.\ulcorner This paper presents the recovery method as a selecting way of more efficient path in MPLS network that reduces the service interruption time. In order to increase the efficiency of usage of recovering resource which is one of major functions of disorder recovering, it opens the state information of each Node both to fault detector and bandwidth broker so that it reduces message transmission time for recovery when functional disorder occurs. in addition, by effective management and adjustment of required bandwidth of entire network depending on the changes of traffic load, it improves the efficiency of bandwidth usage. and in MPLS network supporting priority selection function, it allocates domains depending on the traffic relating to priority order to the entire network so that\ulcorner it efficiently allocates proper resources to the restoring process between the entry and the end for the traffic of high priority and for low priority traffic, it restores path oかy inside disordered domain. by doing this, it reduces resetting time and unnecessary massage transmission.

• The Korean Journal of Applied Statistics
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• v.26 no.1
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• pp.23-36
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• 2013

In this study, we investigate how churn customers (who play a central connector or broker role) affect other customers' churn in their call networks with ego-network analysis using call data of a mobile telecom company in Korea. As a result of investigating Reciprocal Network, we found a relationship of attrition among churn customers. Churn provokers who influence other customers' attrition exist in customer churn networks. The characteristics of churn provokers is that they play a central connector and broker role in their groups. The proportion of churn provokers increases and the churn provoker's influence increases because the network is a reciprocal one.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.71-85
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• 2006

The environment of computational grid is composed of the LAN/WAN each of which has different efficiency and heterogeneous network conditions, and where various programs are running. In this environment, the role of the resource selection broker is very important because the work of each node is performed by considering heterogeneous network environment and the computing power of each node according to the characteristics of a program. In this paper, a new resource selection broker is presented that decides the number of work processes to be allocated at each node by considering network state information and the performance of each node according to the characteristics of a program in the environment of computational grid. The proposed resource selection broker has three steps as follows. First, the performance ratio of each node is computed using latency-bandwidth-cpu mixture information reflecting the characteristics of a program, and the number of work processes that will be performed at each node are decided by this ratio. Second, RSL file is automatically made based on the number of work processes decided at the previous step. Finally, each node creates work processes by using that RSL file and performs the work which has been allocated to itself. As experimental results, the proposed method reflecting characteristics of a program, compared with the existing (uniformity) and latency-bandwidth method is improved $278%\sim316%,\;524%\sim595%,\;924%\sim954%$ in the point of work amount, work process number, and node number respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4B
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• pp.444-454
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• 2004

To support diverse transmission requirements of multimedia applications, Quality of Service (QoS) should be provided in the Internet, where only the best-effort service is available. In this paper, we describe our recent effort on the implementation and verification of an extendable and flexible QoS allocation and resource management system based on the bandwidth broker model for realizing the IETF differentiated service (DiffServ). Focusing on the bandwidth issue over single administrative domain, the implemented system provides real-time resource reservation and allocation, delayed call admission control, simple QoS negotiation between sewer and users, and simple resource monitoring. The implemented system is verified by evaluating the performance of a resource-intensive application over the real-world testbed network.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.5
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• pp.859-870
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• 2020

The MQTT-SN (Message Queuing Telemetry Transport-Sensor Network) protocol is a message transmission protocol used in a sensor-based Internet of Things (IoT) environment. This MQTT-SN protocol is a publish-subscribe model with a broker in the middle of message transmission, and each IoT device sends and receives messages through an intermediary when delivering messages. However, the MQTT-SN protocol does not provide security-related functions such as message security, mutual authentication, access control, and broker security. Accordingly, various security problems have recently occurred, and a situation in which security is required has emerged. In this paper, we review the security requirements of MQTT-SN once again, and propose a modified protocol that improves security while satisfying the constraints in the environment where the resource of IoT to which this protocol is applied is limited. Unlike the existing protocol, the security field and authentication server have been added to satisfy the security requirements. In addition, the proposed protocol is actually implemented and tested, and the proposed protocol is evaluated for practical use in terms of energy consumption.

• Journal of Distribution Science
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• v.4 no.2
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• pp.123-144
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• 2006

For the property right's protection of the nation, the uncertainty's dissolution and the reliability's security of real estate trade are very important. With the life style's change, the market of real estate becomes diversification, and the level of the real estate trade becomes diversification. But compared with this, the trade system of the real estate has not broken away from the mode in the past yet. To cope with it actively, it needs to review the real estate trade form. Especially, it needs to investigate a plan that can advance the Agency Listing method. The Exclusive Agency Listing and the real estate Information Network System have been the usual system in some advanced countries like America, Japan. It is the system that establishes the real estate brokerage's trade order and encourages the execution for the real estate client's property right's protection and benefit offer. In our country, The Exclusive Agency Listing and the real estate Information Network System were created in the revised real estate brokerage law in 12, 1993. But because of varies of questions, it can not be settled down. So this paper will develop the characteristic factors of the Exclusive Agency Listing and the real estate Information Network System revitalization and examine the mutual relation depends on the factors. And these factors were studied through the proved analysis to the effecting made on the Agency function's consideration and real estate broker' trust and customer satisfaction. So depends on these, the existed value now will present the revitalization plan and political implication about the Exclusive Agency Listing and the real estate Information Network System.