• Journal of KIISE:Information Networking
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• v.37 no.4
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• pp.312-316
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• 2010

In this paper, we propose a game theoretic channel sharing model that allocates resources of a base station between MNO(Mobile Network Operator) and MVNO(Mobile Virtual Network Operator) in a fair and efficient manner. Considering the input traffic loads of MNO and MVNO, the proposed model uses the bargaining game theory to allocate channel resources between MNO and MNVO. When the input loads of the carriers are asymmetric, the proposed model increases the resource utilization by allocating more channel resources to the operator with high input load. In addition, the proposed model prevents the quality of service of an operator from degrading even if the input load of the other operators increases excessively.

• Journal of KIISE:Information Networking
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• v.37 no.4
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• pp.263-271
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• 2010

SIP/RTP-based VoIP services are being popular. Recently, however, VoIP anomaly traffic such as delay, interference and termination of call establishment, and degradation of voice quality has been reported. An attacker could intercept a packet, and obtain user and header information so as to generate an anomaly traffic, because most Korean VoIP applications do not use standard security protocols. In this paper, we propose three VoIP anomaly traffic generation methods for CANCEL;BYE DoS and RTP flooding, and a detection method through flow-based traffic measurement. From our experiments, we showed that 97% of anomaly traffic could be detected in real commercial VoIP networks in Korea.

• Journal of KIISE:Information Networking
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• v.27 no.1
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• pp.1-11
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• 2000

Recently, the explosive popularity of Internet gave birth to researches on Distributed Virtual Environments(DVE). They aim at providing a shared application data environment at realtime for users participating in the same application session across Internet. As more users join the session, and as more multimedia data are shared, because of network resource limitation, it is more difficult to maintain the quality of DVE, such as users' satisfaction level. Previous works mainly tried to solve the scalability, synchronization and data transport issues at the application level, with limited success. We suggest a new network centric solution, that consists of a novel network architecture and protocols upon which any large-scale DVE application can be easily developed. The performance of the proposed scheme, called GAIA, is verified by simulation.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06d
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• pp.419-424
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• 2007

인터넷 사용자가 기하급수적으로 증가하고 컴퓨터 및 통신 기술이 발전하면서 전자상거래(electronic commerce)가 일반인에게 급속하게 확산되고 있으나 기존의 신뢰성 관리구조는 판매자(seller)와 구매자(buyer)의 개인적 성향을 충분히 반영하지 못한다는 문제가 있다. 하지만 전자상거래 주체들의 개인적 성향은 전자상거래에서 발생하는 트랜잭션들의 위험성을 감소시키는 매우 중요한 요소 중 하나이다. 그러므로 본 논문에서는 판매자와 구매자들의 개인적 성향에 근거한 신뢰성 관리구조를 제안한다. 제안된 구조는 기존의 신뢰성 관리구조에서 무시되었던 개인 성향 정보들을 활용하기 때문에 기존 구조에 비해 정확하고, 효율적인 신뢰성 관리를 수행할 수 있도록 한다. 또한 본 논문에서는 설문조사를 통해 개인적 성향이 반영되어 평가된 신뢰값에 의해 전자상거래 서비스들의 품질이 개선됨을 보이도록 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.10
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• pp.24-33
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• 2001

Delay, delay variation and packet loss rate are principal QoS(Quality of Service) elements of packet communication. This paper proposes a new buffer allocation mechanism to improve the packet loss performance in such a situation that multiple logical buffers share a single physical memory buffer. In the proposed buffer allocation mechanism, the movement of dynamic threshold follows a curved track instead of a straight line which is used in the DT(dynamic threshold) mechanism. In order evaluate the effectiveness of the proposed mechanism, it is compared with the existing previously proposed mechanisms in several aspects including NC(no control), ST(Static Threshold) and DT mechanisms.

• Journal of the Korea Safety Management & Science
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• v.11 no.2
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• pp.187-195
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• 2009

Various kinds of service measurement including the development of the measurement of service quality have been developed. Especially the mobile telecommunication service being represented by the mobile communication company would be the mostly developed area. Its service development can be understood along with the development of the telecommunication companies as well as cellular companies. It is a differentiated phenomenon in the current research, such as the organic influence between the service quality and product. Of course there are such products placed on sale and enjoyed the common service, but at present there is another case that the product is on the market exclusively with the mobile company in here. This article is to estimate service efficiency for Mobile Communication and Cellular company. In this paper, We tried to measure the service quality and overall satisfaction by using Data Envelopment Analysis(DEA), degree of combination and top2box which is a little bit different methodology from traditional ones. This paper uses CCR model in DEA to measure service efficiency in the Mobile Communication.

• Journal of KIISE:Information Networking
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• v.28 no.3
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• pp.417-425
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• 2001

Since First-Come-First-Served discipline makes it difficult to satisfy the diverse quality of scrvicc(QoS) requirements for each c-oonection, traffic isolation has been proposed for guaranteeing the desired QoS through explicit bandwidth allocation to each virtual connection(VC) in A TM networks. For this purpose, we propose a rate-controlled cell multiplexer using a simple "periodic token-based regulator" per- Vc. The proposed multiplexer realizes VC isolation, while still operating work'||'&'||'not;conservingly. We first discuss its major properties, and then examine its features with respect to the characteristics of the output traffic streams and the traffic isolation of individual VC's, by simulation.n.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.407-410
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• 2001

EDI 시스템은 많은 기업들에게 정보통신기술을 활용하여 업무처리시간 및 비용을 절감하고, 품질을 향상시키기 위한 대안으로 사용되어졌다. 그리고, 인터넷으로 인해 세계 어느 곳에서나 필요한 정보를 볼 수 있게 되었으며, 그 와중에 차세대 EDI 시스템들이 출현하였다. 그 중 다양한 문서구조 표현이 가능한 XML 을 활용한 XML/EDI 가 급속하게 확산되었다. 이러한 시스템들은 네트워크를 통해 정보가 전달되므로 보안에 아주 예민하다. 보안 서비스에도 여러 가지가 있지만 전자서명은 큰 비중을 차지한다. 현재 공개키 암호 알고리즘을 이용한 일반적인 전자 서명을 사용하고 있으나 웹에서 표준화가 되어 가고있는 XML 을 이용한 전자서명 기법이 W3C 에서 제안되어 표준화가 진행되고 있으며 이는 EDI 시스템에서 아주 유용하게 이용 가능한 기술이다. 본 논문에서는 전자 문서 교환에 있어서 중요하다고 할 수 있는 XML 전자서명을 XML/EDI 에 적용하여 시스템을 설계하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.215-218
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• 2012

스팟 인스턴스(Spot instance)는 클라우드 환경에서 사용자가 제시한 입찰 가격으로 클라우드 내의 자원을 이용하여 작업을 수행할 수 있게 하는 새로운 방식이다. 사용자는 자신의 입찰 금액이 클라우드 내의 스팟 인스턴스 가격을 초과하는 한 인스턴스를 실행할 수 있다. 그러나 입찰 가격이 스팟 가격보다 낮다면 작업 실패가 발생하고, 이로 인해 작업 완료 시간은 지연되며 서비스 품질은 저하된다. 이 문제를 해결하기 위해, 본 논문에서는 스팟 인스턴스에서 사용자 비드가 초과되어 작업 수행이 중지된 VM에 대하여 체크포인트 기법과 VM 이주(migration) 기법을 이용함으로써 작업 대기 시간을 줄이는 방법을 제안한다. 이는 작업 중인 스팟 인스턴스에서 작업 실패가 발생할 경우 다른 인스턴스로 이주하여 작업을 재수행하는 기법이다. 실험 결과는 제안하는 VM 이주 기법이 작업을 수행할 수 있는 스팟 인스턴스의 가용성을 증가시킬 수 있음을 보여준다.

• Journal of IKEEE
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• v.28 no.1
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• pp.72-77
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• 2024

In this paper, a triple-mode frequency-tunable filter is proposed to meet the recent demands of various frequency bands of mobile communication services. This filter has a tunable structure that can adjust the resonance frequency using a variable capacitor. To improve the quality factor, a SIW(Substrate Integrated Waveguide) structure was introduced and a structure that induces three resonance modes was implemented through a circular hole located in the center. The change in electric field distribution and resonance frequency by the variable capacitor was simulated using HFSS, and the change in electric field distribution and resonance frequency of Triple Mode mode was confirmed.