• Journal of the Korea Society for Simulation
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• v.6 no.2
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• pp.45-57
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• 1997

MAC (media access control) bridge is used to interconnect separate LANs and to relay frames between the BLANs (bridged LANs). Bridge architecture consists of MAC entity, MAC relay entity and bridge protocol entity protocol entity and performs learning, filtering and forwarding functions using filtering database. In this paper, we simulate these functions of bridge and the STP (spanning tree protocol). The STP derives an active topology from an arbitrarily connected BLAN. Our simulation model assumes a BLAN consisted of three bridge forming a closed loop. In order to remove the loop, each bridge process exchanges configruation BPDU (bridge protocol data unit0 with other bridge processes connected to the bridge itself. To simulate the communication between bridges, we implement the IPC (inter-process communication) server using message queues. Our simulation results show that the assumed BLAN contains no closed loop and then there is no alternative route and no unnecessary traffic.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.701-708
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• 2005

Structuring mechanism, important to serve messages in post-office box structure, is to construct the hierarchy of classes according to the contents of message objects. This Paper Proposes $\alpha$-cut based genealogy grouping method to cluster a lot of structured objects in application domain. The proposed method decides the relationship first by semantic similarity relation and fuzzy relation, and then performs the grouping by operations of search( ), insert() and hierarchy(). This hierarchy structure makes it easy to process group-related processing tasks such as answering queries, discriminating objects, finding similarities among objects, etc. The proposed post-office box structure may be efficiently used to serve and manage message objects by the creation of groups. The Proposed method is tested for 5500 message objects and compared with other methods such as non-grouping, BGM, RGM, OGM.

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.201-208
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• 2005

Event notification service is a event-based messaging middleware service needed for various vertical domains, such as, business applications, distributed system management, and web service integration. In this paper, we investigate the architecture of an event notification service that includes a subject-based event dissemination service and a flexible message communication service. The event dissemination service is in charge of transferring events asynchronously but speedy according to the subjects of events and their environmental knowledge. It also includes content-based message filtering. The message communication service provides a common communication infrastructure supporting variety types of messages and variety of protocols. Depending on application domains and situation, we can re-configurate the communication infrastructure in order to optimize the efficiency and usability. This paper shows the performance analysis of our event notification service with various types of message formats and protocols.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.4
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• pp.405-414
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• 2010

According to the statistics of SecurityFocus in 2008, client-side attacks through the Microsoft Internet Explorer have increased by more than 50%. In this paper, we have implemented a behavior-based malicious web page detection system and a blacklist-based malicious web page filtering system. To do this, we first efficiently collected the target URLs by constructing a crawling system. The malicious URL detection system, run on a specific server, visits and renders actively the collected web pages under virtual machine environment. To detect whether each web page is malicious or not, the system state changes of the virtual machine are checked after rendering the page. If abnormal state changes are detected, we conclude the rendered web page is malicious, and insert it into the blacklist of malicious web pages. The malicious URL filtering system, run on the web client machine, filters malicious web pages based on the blacklist when a user visits web sites. We have enhanced system performance by automatically handling message boxes at the time of ULR analysis on the detection system. Experimental results show that the game sites contain up to three times more malicious pages than the other sites, and many attacks incur a file creation and a registry key modification.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.1
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• pp.155-163
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• 2014

To enhance network efficiency, content-centric networking (CCN) proposes that intermediated network nodes on a content-delivery path temporally cache transmitted contents. Then if an intermediated node receives a content request message (Interest) for previously cached content, the node directly transmits the cached content as a response message (Data) to requestors and finishes the transmission of the received Interest. Since Interest is performed by intermediated network nodes, it is possible to efficiently transmit contents and to effectively solve a network congestion problem caused around contents sources. For that, CCN utilizes both content store to temporarily cache content and pending Interest table (PIT) to record Interest incoming Face. However, it has mentioned the possibility of denial service attack using both the limitation of PIT resource and fake Interests. In this paper, we briefly describe the presented PIT flooding attack utilizing fake Interest. Then we introduce new attack possibility using fake Data and propose a countermeasure for the proposed attack. Also we evaluate the performance of our proposal.

• Journal of the Korea Society for Simulation
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• v.18 no.4
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• pp.1-8
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• 2009

The distributed war-game simulation system has been used to represent the virtual battlefield environment. In order to produce a simulation result, simulators connected from a network transfer messages with location information of simulated objects to a central simulation server. This network traffic is an immediate cause of system performance degradation. Therefore, the paper proposes a system to manage and control network traffic generated from distributed war-game simulation. The proposed system determines the moving distance of simulated objects and filters location messages by a distance threshold which is controlled according to system conditions like network traffic and location error. And, the system predicts the next location of simulated objects to minimize location error caused by message filtering. Experimental results demonstrate that the proposed system is effective to control the network traffic of distributed war-game simulation systems and reduce the location error of simulated objects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1B
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• pp.73-85
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• 2004

SIn this paper, we introduce our experience for designing and implementing new concept of a global XML-based Peer-to-Peer (P2P) engine to support various P2P applications, and interconnection among PC, Web and mobile computing environments. The proposed P2P engine can support to heterogeneous data exchanges and web interconnection by facilitating with the text-base XML while message exchange are necessary. It is also to provide multi-level security functions as well as to apply different types of security algorithms. The system consist of four modules; a message dispatcher to scheduling and filtering the message, a SecureNet to providing security services and data transmission, a Discovery Manager to constructing peer-to-peer networking, and a Repository Manager to processing data management including XML documents. As a feasibility test, we implement various P2P services such as chatting as a communication service, white-board as an authoring tool set during collaborative working, and a file system as a file sharing service. We also compared the proposed system to a Gnutella in order to measure performance of the systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.908-913
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• 2009

Mobile phones became important household appliance that cannot be without in our daily lives. And the short messaging service (SMS) in these mobile phones is 1.5 to 2 times more than the voice service. However, the spam filtering functions installed in mobile phones take a method to receive specific number patterns or words and recognize spam messages when those numbers or words are present. However, this method cannot properly filters various types of spam messages currently dispatched. This paper proposes a more powerful and more adaptive spam filtering system using SVM and thesaurus. The system went through a process of isolating words from sample data through pro-processing device and integrating meanings of isolated words using a thesaurus. Then it generated characteristics of integrated words through the chi-square statistics and studied the characteristics. The proposed system is realized in a Window environment and the performance is confirmed through experiments.

• Korean Journal of Cognitive Science
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• v.21 no.1
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• pp.145-156
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• 2010

This paper presents a new contents-based digital still image protection method which includes a copyright message. Since the existing method using gradient values used a pixel based $3{\times}3$ Sobel operator, it was sensitive to attacks and could not extract exact copyright message. Therefore, in this paper, we present a algorithm which uses block based OCL(Orientation Certainty Level) instead of pixel. The experimental results show that the proposed scheme not only has good image quality, but also is robust to JPEG lossy compression, filtering, sharpening, blurring and noise. Moreover, the proposed algorithm has good performance more than 10% in rotation attacks than the existing method.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.1
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• pp.24-30
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• 2006

The Controller Area Network (CAN) is being widely used for real-time control application and small-scale distributed computer controller systems. When the stuff bits are generated by bit-stuffing mechanism in the CAN network, it causes jitter including variations in response time and delay In order to eliminate this jitter, stuff bits must be controlled to minimize the response time and to reduce the variation of data transmission time. This paper proposes the method to reduce the stuff bits by restriction of available identifier and bit mask using exclusive OR operation. This da manipulation method are pretty useful to the real-time control strategy with respect to performance. However, the CAN may exhibit unfair behavior under heavy traffic conditions. When there are both high and low priority messages ready for transmission, the proposed precedence priority filtering method allows one low priority message to be exchanged between any two adjacent higher priority messages. In this way, the length of each transmission delays is upper bounded. These procedures are implemented as local controllers for the ISHURO(Inha Semvung Humanoid Robot).