• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.1
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• pp.55-61
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• 2002

Real-time Internet multi-media services requires fast data transmission, QoS and IP multicast. MARS is proposed to support IP multicast in the ATM Networks based on Internet, and RSVP is proposed to guarantee QoS in the Internet which is originally based on only best-effort service. In this paper, we propose two mechanisms to support IP multicast service involving QoS support over the ATM networks with MARS architecture based on multiple MCSs. In the first mechanism, when an ATM host requests joining into a specific multicast group, the MARS selects a proper MCS among the multiple MCSs to minimize the average time of transfer delay between the sender and the group members. In the second mechanism, when the RSVP reservation message from group member arrive at the MARS, the MARS which can process the RSVP reservation message select again the MCS with using the MCS management table. Finally, we recommend the mechanism to keep the QoS of Internet service and to reduce the processing-overhead between MARS and MCS.

• Journal of KIISE:Databases
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• v.30 no.4
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• pp.397-407
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• 2003

Transactions of updating spatial dta with mobile clients are log transactions because a user disconnected from a server surveys real features and updates them. In this environment, it is appropriate to exploit the optimistic approach based on the validation test in order to control the concurrency of transactions. On the contrary, the pessimistic concurrency control scheme makes transactions wait for a long time due to the lock. In this paper, we propose the surrogate transaction model and implement its manager for the S-S-M(Server-Surrogate PC-Mobile Client) structure which is appropriate for updating spatial data in mobile environments. In the S-S-M structure, the mobile client communicates with the server by the surrogate PC. We extend the validation condition in consideration of spatial relationships between spatial objects in this model. We also present the commit protocol where the user of a surrogate PC adjusts objects of the conflicted surrogate transaction to minimize costs for the abortion of the transaction.

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.2
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• pp.165-179
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• 2005

Close collaboration among businesses is required in B2B EC environment. Furthermore, emergency requests or critical information among businesses should be processed in an immediate mode. Most current systems, however, due to firewalls for the systems' security and autonomy, can not handle these requirements appropriately, but handle them in an ad hoc manner In this paper a method of timely collaboration among businesses and an active functionality component to support it in B2B EC environment are proposed. Since the active functionality component supports high level ECA rule patterns and event-based immediate processing, system administrators and programmers can easily program and maintain the timely collaboration independently to the application logic. The proposed active functionality component uses HTTP protocol to be applied through firewalls and is designed using a commercial DBMS for practical purpose.

• Journal of KIISE:Information Networking
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• v.30 no.5
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• pp.621-630
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• 2003

In this paper, we implemented SIP protocol that supports IPv6 and differentiated call processing scheme for NGN(Next Regeneration Network). In NGN, SIP processes call signaling among various application services. A softswitch and SIP server must give priority to sensitive services such as Fax, network management and home networking that require a fast call setup time. Also, the support of IPv6 is needed under consideration of All-IP. We proposed differentiated call processing scheme. The differentiated call processing scheme supports differentiated call processing as priority of service class on call processing in SW server We defined three service classes and use the Flow Label field of the IPv6 header for setting service class. Through the performance analysis, we proved that it improves throughput for call message with the high priority. The result of performance analysis demonstrates that differentiated call processing scheme gives better performance for the service requiring a fast session establishment in NGN.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.8
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• pp.327-334
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• 2013

Today's network traffic has become extremely complex and diverse since the speed of network became faster and a variety of application services appear. Moreover, many applications appear and disappear fast and continuously. However, the current traffic classification system does not give much attention to this dynamic change of applications. In this paper, we propose an application awareness system in order to solve this problem. The application awareness system can provide the information, such as the usage trend of conventional applications and the emergence of new applications by recognizing the application name in a rapidly changing network environment. In order to recognize the application name, the Host field of HTTP protocol has been utilized. The proposed mechanism consists of two steps. First, the system generates the candidates of application name by extracting the domain name from the Host field in HTTP packet. Second, the administrator confirms the name afterward. The validity of the proposed system has been proved through the experiments in campus network.

• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.511-520
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• 2006

WebDAV is a protocol which supports web-based distributed authoring and versioning, providing a standard infrastructure for asynchronous collaboration on various contents through the Internet. Current WebDAV-enabled authoring applications that support WebDAV, such as Microsoft office, Photoshop, or Dreamweaver, work by integrating WebDAV capabilities into the application. While this approach provides solid support for collaborative authoring, it has a drawback that each of the applications needs to support WebDAV capabilities in its own way. We developed a WebDAV client named DAView running on Linux KDE, which enables WebDAV-unaware authoring tools to have effective remote authoring capabilities. DAView provides a GUI view of a WebDAV server, similar to existing WebDAV-enabled file managers such as DAVExplorer. Unique among WebDAV file managers, it also provides the ability to launch the authoring application associated to a WebDAV server resource, automatically managing the locks on the resource.

• The Transactions of the Korea Information Processing Society
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• v.6 no.12
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• pp.3652-3661
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• 1999

To support multimedia applications such as a multimedia communication systems and multimedia broadcasting, an operating system need to predict their timing-constraints. So, In this real-time systems, we must solve the priority inversion problem that may make the behavior of unpredictable systems and need a real-time server model that provides a better preemptability and minimizes a system overhead. In current real-time systems, the single thread server model, the worker model and the dynamic server model are being used for synchronization but they cannot propose an effective structure for managing shared resources. In this paper, the priority inheritance protocol is used to solve the priority inversion problem and the hybrid prioritized worker model is proposed, which can provide a more effective structure and a faster response time minimizing a system overhead. The hybrid prioritized worker model is to combine the static and the dynamic prioritized worker model, and have a better performance than other models in response time which is an important factor in a real-time system.

• Journal of the Korea Computer Industry Society
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• v.2 no.7
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• pp.983-996
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• 2001

Mobile Ad Hoc Network (MANET) is a network architecture which has no backborn network and is deployed temporarily and rapidly in emergency or war without fixed mobile infrastructures. All communications between network entities are carried in ad-hoc networks over the wireless medium. Due to the radio communications being extremely vulnerable to propagation impairments, connectivity between network nodes is not guaranteed. Therefore, previously developed routing algorithms in wired networks cannot be used. And many new algorithms have been undergone. This study proposes the Secondary Header approach to the cluster based routing protocol (CBRP). In case, the main header becomes abnormal status so that the main header can not participate the communications between network entities, the secondary header immediately replaces the primary header without selecting process of the new primary header. The performances of proposed algorithm CBRP-SH(Cluster Based Routing Protocol using Secondary Header) are compared with CBRP and results are presented in order to show the effectiveness of the algorithm.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.80-84
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• 2010

Data multicasting from a source to multiple sinks in wireless sensor networks is used to achieve both reducing communication costs and energy efficiency. Almost all existing schemes for the multicasting might be effectively performed by optimal construction of a multicasting tree between a source and multiple stationary sinks. However, in practical sensor applications, sinks could move around on the wireless sensor networks for own missions, such as scouting of soldiers and saving lives of victims by firefighters. Unfortunately, the sink mobility causes frequent entire reconstruction of the multicasting tree and thus it leads to exhaustion of battery power of sensors. Hence, we propose an energy-efficient multicast protocol to support multiple mobile sinks by the local multicast tree reconstruction, called Local Update-based geographic Multicasting for Mobile sinks (LUMM) for wireless sensor networks. Our simulation results show that our scheme for mobile sinks is more efficient in terms of energy resource management than other exist works.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.5
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• pp.106-121
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• 2008

In this paper, we proposed and designed the protocol for energy efficiency and the center of data aiming at the design of a Multi Location Awareness System that recognizes a shadow site in parking and tunnel, which stands on the basis of CSS(Chirp Spread Spectrum) method using ISM Band of IEEE 802.15.4a that aware close location with wireless RF only. As a result of the protocol measurement, it displays the observation errors of less than 15cm, the data error rate of less than 5%, and can implement the Multi Location Awareness System with maximum length of life for 13.5 days using battery of 3V(1500 mAh).