• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1210-1220
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• 2016

As modern warfare has changed into network centered, the ability to share situational awareness among allies become a core competency for performing operational missions. In an airborne environment, it uses a tactical data link such as Link-16 for shared situational awareness. There exist problems when it shares situational awareness over the existing data link that can not allocate slots dynamically or that can not change the number of a slot to be allocated. In addition, there was a problem that can not share this failure so that failed to improves situation awareness because of finite time slot resources. In this paper, we accommodate dynamic slot allocation and changes of slot allocation with mixed structure of TDMA (time division multiple access) and random access. We propose a technique that can be used when available slots are exhausted, and a load balancing method to prevent slot allocation delay when slot requesting or message sending is concentrated on a single subframe.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.378-382
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• 2001

There are some technical problems in current internet-broadcasting. The load of server rises in proportion to user connection. And the inefficient usage of network bandwidth deteriorates quality of services and doesn't transport multimedia data in real time. To overcome above problems, multicast transport technology is applied to real-time multimedia data transport. But the reliability problem is still remained. This paper provides an efficient design of internet broadcasting server. We propose an multimedia data transport algorithm using adaptive encoding by grouping users according to similar connection environment. Performance evaluations show that the mechanism decreases the load of server and improves the quality of services.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.12
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• pp.455-462
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• 2014

In recent years, various services in mobile environments due to the growth of mobile devices and related techniques like wireless networks. Furthermore, as the increasing communication traffic in cellular networks has become a new significant issue, many studies for device-to-device(D2D) communication and D2D-based cooperative services have been performed recently. In this paper, we design a smart agent system for D2D-based cooperative services and propose a dynamic service binding method based on service ontology. We classify roles of mobile devices for cooperative services by defining three types of smart agents, and construct a knowledge base in order to describe properties of 'service' unit. The proposed knowledge model, D2D cooperative service ontology, can enable a autonomous cooperative services between mobile devices by binding a requested service to the appropriate member device according to the real-time context in mobile environments.

• Information and Communications Magazine
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• v.26 no.11
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• pp.22-28
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• 2009

최근 가정이나 사무실 등 옥내 사용자들의 통신 환경의 개선을 위해 펨토셀에 대한 관심이 고조되고 있다. 펨토셀의 서비스 반경 특성상 고정된 대역폭을 효율적으로 사용하는 여러 방법들이 제안되고 있으며, 이는 향후 통신환경에서 중요한 이슈로 대두되고 있다 [1]-[3]. 본고에서는 3GPP-Long Term Evolution (LTE) 환경에서 물리 계층 표준의 프레임 구조를 살펴보고, 3GPP-LTE 구조에 여러 펨토셀이 적용되었을 때 효율적인 간섭회피 방법을 제안한다. 펨토셀 환경은 사용자에게 서비스를 제공하는 반경이 넓지 않아 주파수 대역의 재사용이 용이하다. 이와 같은 특성을 이용하여 전체 시스템에 부하를 최소화할 수 있는 분산형 동적 대역폭 조정을 수행하는 방법을 제안한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.106-113
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• 2008

In this paper, we will design and substantiate the Network Traffic management system(MAGI), which makes up for the weak points of existing Network Monitoring tools and realize dynamic firewall; MRTG, ntop, ethereal, and nettest. The Network Traffic Monitoring and analyzing system differs from existing software-based Network Monitoring tools as MAGI is a combination of software and hardware. Not only the innovative web user interface applied to the software makes analyzing traffic simpler, but it also has a function for monitoring and managing conditions of the hardware. The web user interface implemented with PHP and MySQL helps to use the database and as a result, analyzing data becomes easier. On the hardware part, the appliance is configured as a bridge in a network. As a result, managed system does not have overload.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1144-1150
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• 2015

Presence information provides various informations about users such as on-line status, current location, network connection method and connection address, and there are two kinds of presence information, SIP(Session Initiation Protocol) based presence information and XMPP(Extensible Massaging and Presence Protocol) based presence information. In this paper, a multiple server architecture that can handle these two kinds of presence information has been proposed. In this architecture, severs are added dynamically according to number of users to provide system scalability, and load of each server can be effectively controlled. In this system, a new XMPP stanza architecture and presence information data format are designed for load control. Furthermore message exchanging procedures between servers and users for dynamic server control has been also suggested. The performance of the proposed system has been analysed by simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.907-915
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• 2003

A very efficient packet transmission scheme is needed in the radio environment where radio resource is insufficient as compared with the environment of the wired communication. In general, dual mode packet transmission scheme is used broadly. Packets are transmitted through the dedicated or common chamois according to a switching criterion. The general criteria are the length and generation frequency of packet, that is, large and frequent packets are transmitted using a dedicated channel and small and infrequent packets are transmitted using a common channel. The performance of dual mode packet transmission scheme is closely related to the switching criteria. However, it is very difficult to find the optimal switching point because that is not fixed but variable according to the environment such as traffic load, length of generated packets, and the number of channels. In this paper, a new scheme for the dual mode packet transmission scheme using a dynamic switching threshold is proposed where the switching threshold is not fixed but variable according to the network environment. The performance of the proposed method is analyzed using a simulation. From the simulation results, it is shown that the performance of the proposed scheme is not very influenced by the network environment unlike the conventional dual mode packet transmission scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6B
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• pp.544-550
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• 2006

Next-generation wireless/mobile networks are envisioned to have an IP-based infrastructure. One of the research challenges for next-generation all IP-based networks is the design of intelligent mobility management technologies that have a seamless mobility and minimal signaling overhead. Recently, HMIPv6 was proposed by the IETF for efficient mobility management. HMIPv6 reduces the amount of signaling and improves the performance of MIPv6 in terms of handover latency. However the MAP can be a single point of performance bottleneck when there are a lot of local movements. HMIPv6 can cause signaling overhead due to the unnecessary location update of idle mobile nodes. Therefore, in this paper, we propose the dynamic paging Mobile IPv6 that reduces the signaling cost of the unnecessary location updates using IP paging and organizes dynamically optimal MAP area according to user's mobility and traffic. We show performance results that are obtained from the average total location update cost and packet delivery cost.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.1 no.1
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• pp.52-57
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• 2002

A simulation tool for an optimal ATIS design and drivers' dynamic route choice behavior analysis is developed, which is applicable to urban networks. Due to the difficulty to make drivers feel the time pressure according to traffic conditions, current SP questionnaire survey type surveys have a limitation to capture correct driver reactions to real-time traffic Information provision. The simulator Is a web-based upgraded version, named WATiSim (Web-based ATIS Simulator), to quickly perform a wide population survey with a minimal cost using INTERNET Furthermore, the time pressure issue is lessened by its interface and simulation modules. After WATiSim mimicked a VMS based ATIS in a partial network of Seoul Metropolitan, reactions of drivers to various traffic conditions were surveyed through INTERNET and analyzed using a logit model. Drivers under the ATIS environment clearly understood the provided traffic information, and their reactions were closely related to traffic conditions, scheduled delay, trip purposes as well as toll charge if any.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.829-831
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• 2005

최근 컴포넌트 기반 미들웨어의 최적화에 대한 연구가 활발히 이루어지고 있다. CPU점유율이 높은 어플리케이션의 동시 실행은 시스템에 부하를 주기 때문에, 시스템 성능을 약화시키고 실행중인 어플리케이션에 영향을 준다. 컴포넌트 기반 미들웨어는 여러 개의 재사용 가능한 컴포넌트를 조합하여 어플리케이션을 구성하기 때문에 동적으로 재구성이 가능하다. 본 논문은 컴포넌트 기반 미들웨어가 시스템 상황에 대한 정보를 받아들여 시스템의 상황을 스스로 판단하고 자가치료 또는 시스템의 성능을 최적화시키는 컴포넌트를 선택하는 방법을 제안한다. 상황판단을 위해 유연한 추론이 가능하고, 데이터로부터 자동학습이 가능한 베이지안 네트워크를 사용하였다. 두 시간 가량의 데이터를 리눅스 사용자로부터 획득하여 실험한 결과, 테스트 데이터에 대해 $76.5\%$의 성능을 보였다.