• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11B
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• pp.968-980
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• 2008

Providing handover with guaranteed QoS for real-time multimedia service such as VoIP, video/audio streaming, and video conferencing in wireless LAN is a challenging task. In this paper, we present efficient layer 2 handover mechanism in wireless LAN, which can provide fast handover with guaranteed QoS for real-time multimedia service. To this end, the scanning period and the number of channels per scanning for handover are dynamically adapted to the type of applications and wireless networking environment, so that both the degradation of application service quality and signaling overhead are minimized simultaneously. The performance of the proposed mechanism is verified by the simulation. The simulation results show that the proposed mechanism guarantess QoS of each multimedia application with minimal power consumption.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.411-414
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• 2001

The rapid technical development is changing the environment in the telecommunications industry that is the convergence among technologies, the intensive competition, and so on. Standardization is the core issue in the telecommunications industry, and it is recognized the important strategy to preempt a market by all firms. The telecommunication industry has far-reaching effects to the other industries, so firms in the telecommunications industry compete intensively against one another build on early lead. Because the defeat in standardization competition cause the pertinent nation a great loss. Therefore it shows the intense competition from the early stage in the telecommunications industry. In this paper, we'll examin the change in environment in relation to standardization in the telecommunication and suggest the national policies of standardization.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.5
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• pp.125-133
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• 2008

In this paper, we propose active queue management mechanism (Active-WRED) to guarantee quality of the high priority service class in multi-class traffic service environment. In congestion situation, this mechanism increases drop probability of low priority traffic and reduces the drop probability of the high priority traffic, therefore it can improve the quality of the high priority service. In order to analyze the performance of our mechanism we introduce the stochastic analysis of a discrete-time queueing systems for the performance evaluation of the Active Queue Management (AQM) based congestion control mechanism called Weighted Random Early Detection (WRED) using a two-state Markov-Modulated Bernoulli arrival process (MMBP-2) as the traffic source. A two-dimensional discrete-time Harkov chain is introduced to model the Active-WRED mechanism for two traffic classes (Guaranteed Service and Best Effort Service) where each dimension corresponds to a traffic class with its own parameters.

• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.437-447
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• 2003

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) algorithm. However, RED algorithm simple but does not protect traffic from high-bandwidth flows, which include not only flows that fail to use end-to-end congestion control such as UDP flow, but also short round-trip time TCP flows. In this paper, in order to solve this problem, we propose a simple fairness queue management scheme, called AFQM(Approximate Fair Queue Management) algorithm, that discriminate against the flows which submit more packets/sec than is allowed by their fair share. By doing this, the scheme aims to approximate the fair queueing policy Since it is a small overhead and easy to implement, AFQM algorithm controls unresponsive or misbehaving flows with a minimum overhead.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10B
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• pp.957-964
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• 2003

The circulation of unwholesome information such as obscene and violent information is gradually increasing based on the rapid expansion of information communications infrastructure. Those kinds of information are harmful to the adolescents and even cause social problems so that active countermeasure is requited. In order to cope with the spread of unwholesome information, appropriate regulating methods are absolutely in need by establishing or revising information communications-related laws. In this paper, we had analyzed domestic and foreign programs with existing harmful information blocking method, and then designed and implemented a selective blocking program based on Platform for Internet Contents Selection(PICS) by using selective blocking technology based on Internet contents rating system. We also proposed a compromised rating system blocking method that consists of selective filtering function by age and the popular blocking list. The proposed system has advantages in that there would be no increase in network load resulting from blocking list update and inquiry, it is possible to perform active selective filtering considering user's age, and it may introduce self-imposed rating.

• Journal of Korea Multimedia Society
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• v.11 no.7
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• pp.1016-1024
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• 2008

In this paper, we designed and implemented the ACE(ACtive Emergency call service system) system for emergency call service actively. ACE system has two physical components; E-Device(Emergency Mobile Device) and E-Server(Emergency Server). The role of E-Device is the mobile device in order to call emergency by using mild handi-capped, the elderly and children who are able to communicate theirs intention to another. E-Server is the server for management E-devices with realtime monitering. E-Device will be developed to the portable size for easily mild handi-capped, the elderly and children. When they need the service of emergency call, the button of E-device can be used and the call signal is transmitted to the emergency office and the guardian through Internet and CDMA. E-server should be developed the integrated control system for management of E-Devices basically. And it also supported to realtime monitoring of E-devices with respect to high quality of emergency call service for rise the efficiency.

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.91-102
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• 2006

We analyze the performance of MAC-layer Reed-Solomon error recovery in the cdma2000 1xEV-DO Broadcast and Multicast Services (BCMCSs) environment, with respect to the size of the ECB (Error Control Block) and the air-channel condition, and establish the relationship between ECB size, error recovery capacity and service latency. From this we propose an adaptive error recovery scheme which adjusts the size of the ECB to reflect the environment of the mobile nodes so as to meet the required service quality (target bit error-rate), while reducing the latency of real-time applications. Extensive simulation results show the effectiveness of our approach compared to the current static scheme. Proposed adaptive schemes achieves near optimal solution with respect to service latency while satisfying the required service quality.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.3
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• pp.67-74
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• 2011

In this paper, we presented a dynamic cyber attack tree which can describe an attack scenario flexibly for an active cyber attack model could be detected complex and transformed attack method. An attack tree provides a formal and methodical route of describing the security safeguard on varying attacks against network system. The existent attack tree can describe attack scenario as using vertex, edge and composition. But an attack tree has the limitations to express complex and new attack due to the restriction of attack tree's attributes. We solved the limitations of the existent attack tree as adding an threat occurrence probability and 2 components of composition in the attributes. Firstly, we improved the flexibility to describe complex and transformed attack method, and reduced the ambiguity of attack sequence, as reinforcing composition. And we can identify the risk level of attack at each attack phase from child node to parent node as adding an threat occurrence probability.

• Journal of Convergence for Information Technology
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• v.12 no.4
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• pp.126-132
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• 2022

At present, due to the rapid spread of smartphones and activation of IoT, malicious codes are disseminated using SNS, or intelligent intrusions such as intelligent APT and ransomware are in progress. The damage caused by the intelligent intrusion is also becoming more consequential, threatening, and emergent than the previous intrusion. Therefore, in this paper, we propose an intelligent intrusion situation-aware reasoning system to detect transgression behavior made by such intelligent malicious code. The proposed system was used to detect and respond to various intelligent intrusions at an early stage. The anticipated system is composed of an event monitor, event manager, situation manager, response manager, and database, and through close interaction between each component, it identifies the previously recognized intrusive behavior and learns about the new invasive activities. It was detected through the function to improve the performance of the inference device. In addition, it was found that the proposed system detects and responds to intelligent intrusions through the state of detecting ransomware, which is an intelligent intrusion type.

• Journal of Intelligence and Information Systems
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• v.15 no.1
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• pp.123-140
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• 2009

Collaborative filtering recommends products using customers' preferences, so it cannot recommend products to the new customer who has no preference information. This paper proposes a novel approach to new customer recommendations using the social network analysis which is used to search relationships among social entities such as genetics network, traffic network, organization network, etc. The proposed recommendation method identifies customers most likely to be neighbors to the new customer using the centrality theory in social network analysis and recommends products those customers have liked in the past. The procedure of our method is divided into four phases : purchase similarity analysis, social network construction, centrality-based neighborhood formation, and recommendation generation. To evaluate the effectiveness of our approach, we have conducted several experiments using a data set from a department store in Korea. Our method was compared with the best-seller-based method that uses the best-seller list to generate recommendations for the new customer. The experimental results show that our approach significantly outperforms the best-seller-based method as measured by F1-measure.