• Journal of information and communication convergence engineering
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• 제14권2호
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• pp.84-88
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• 2016

As good example of potential application-specific requirement, (m,k)-firm real-time streams have been recently introduced to deliver multimedia data efficiently in wireless sensor networks. In addition to stream model, communication protocols to meet specific (m,k)-firm real-time streams have been newly developed or extended from existing protocols. However, since the existing schemes for an (m,k)-firm stream have been proposed under typical flat architecture, the scalability problem remains unsolved when the number of real-time flows increases in the networks. To solve this problem, in this paper, we propose a new clustering scheme for an (m,k)-firm stream. The two different clustering algorithms are performed according to either the (m,k)-firm requirement or the deadline. Simulation results are presented to demonstrate the suitability of the proposed scheme under hierarchical architecture by showing that its performance is acceptable irrespective of the increase in the number of flows.

• 한국통신학회논문지
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• 제29권5B호
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• pp.491-497
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• 2004

본 논문에서는, 인터넷 백본 네트워크상에서 악성의 네트워크 공격 트래픽을 고립시킴으로서 네트워크 인프라를 보호하기 위한 트래픽 제어 방법을 제안한다. 제안된 방법은 개별 플로우 또는 개별 패킷들에 기반을 둔 기존의 방법들과 달리 제안된 공격 탐지 및 제어 방법은 집합된 트래픽 수준에서 운영되므로 계산의 복잡성을 현저히 줄일 수 있으므로 네트워크 공격에 대한 전역 인프라 구축에 활용 가능하다. 실험 결과는 제안된 방법에 의한 트래픽 제어가 네트워크 공격이 이루어질 시 정상 트래픽과 네트워크 자원들을 적절히 보호할 수 있음을 보여준다.

• 한국정보통신학회논문지
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• 제10권9호
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• pp.1700-1709
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• 2006

본 논문에서는 인터넷으로 연결된 컴퓨터를 이용하여 전화교환 및 통신이 가능하도록 하는 B-ISDN 기반의 IP-PBX 시스템의 구현을 위한 개발방법 및 설계에 관해 연구하였다. IP-PBX 시스템의 단말과 서버의 구조를 설계하고 호제어를 위한 메세지와 자료구조의 정의와 상태천이를 설계하였고, 사용자간 통화를 위한 착발신 단말 간의 호제어와 부가서비스의 메세지 흐름을 설계하고 복수 호 제어방법을 연구하였다.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2004년도 춘계학술대회
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• pp.91-101
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• 2004

The turbulent flow is of fundamental interest because the conservation equations for thermodynamics, mass and momentum are linked together. This turbulent flow consists of some coherent time- and space-organized vortical structures. Research has already shown that some dynamic systems and experimental models still cannot provide a good nonlinear analysis of turbulent time series. In the real turbulent flow, very complicated nonlinear behaviors, which are affected by many vague factors are present. In this paper, a kernel-based machine for fuzzy nonlinear regression analysis is proposed to predict the nonlinear time series of turbulent flows. In order to show the practicality and usefulness of this model, we present an example of predicting the near-wall turbulence time series as a verifiable model and compare with fuzzy piecewise regression. The results of practical applications show that the proposed method is appropriate and appears to be useful in nonlinear analysis and in fuzzy environments to predict the turbulence time series.

• 대한수학회지
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• 제46권2호
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• pp.225-236
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• 2009

The equicontinuity and scattering properties of continuous semi-flows are studied on a compact metric space. The main results are obtained as follows: first, the complexity function defined by the spanning set is bounded if and only if the system is equicontinuous; secondly, if a continuous semi-flow is topologically weak mixing, then it is pointwise scattering; thirdly, several equivalent conditions for the time-one map of a continuous semi-flow to be scattering are presented; Finally, for a minimal continuous map it is shown that the "non-dense" requirement is unnecessary in the definition of scattering by using open covers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권2호
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• pp.134-146
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• 2009

Traffic classification seeks to assign packet flows to an appropriate quality of service(QoS) class based on flow statistics without the need to examine packet payloads. Classification proceeds in two steps. Classification rules are first built by analyzing traffic traces, and then the classification rules are evaluated using test data. In this paper, we use self-organizing map and K-means clustering as unsupervised machine learning methods to identify the inherent classes in traffic traces. Three clusters were discovered, corresponding to transactional, bulk data transfer, and interactive applications. The K-nearest neighbor classifier was found to be highly accurate for the traffic data and significantly better compared to a minimum mean distance classifier.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권12호
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• pp.5174-5190
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• 2016

Recent years have witnessed an explosive growth of mobile devices, mobile cloud computing services offered by these devices and the remote clouds behind them. In this paper, we noticed ultra-low latency service, as a type of mobile cloud computing service, requires extremely short delay constraints. Hence, such delay-sensitive applications should be satisfied with strong QoS guarantee. Existing solutions regarding this problem have poor performance in terms of throughput. In this paper, we propose an end-to-end bandwidth resource reservation via software defined scheduling inspired by the famous SDN framework. The main contribution of this paper is the end-to-end resource reservation and flow scheduling algorithm, which always gives priority to delay sensitive flows. Simulation results confirm the advantage of the proposed solution, which improves the average throughput of ultra-low latency flows.

• 전자공학회지
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• 제30권9호
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• pp.1002-1011
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• 2003

In this paper, we introduce an integrated SoC front-end design & verification environment which can be practically used in the embedded 32-bit processor-core SoC VLSI design. Our introduced SoC design & verification environment integrates two most important flows, such as the RTL power estimation and code coverage analysis, with the functional verification (chip validation) flow which is used in the conventional simulation-based design. For this, we developed two simulation-based inhouse tools, RTL power estimator and code coverage analyzer, and used them to adopt them to our RTL design and to increase the design quality of that. Our integrated design environment also includes basic design and verification flows such as the gate-level functional verification with back annotation information and test vector capture & replay environment.

• 한국통신학회논문지
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• 제11권1호
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• pp.1-15
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• 1986

Optic flow는 이동물체표면의 3차원 속도를 영상판(image plane)에 투영시킨 2차원 속도이다. 본 논문은 이 동물체의 연속영상으로부터 optic flow 를 구하는 기술들을 조사분석하고 정해진 optic flow로부터 물체의 인식 및 3차원 속도를 결정하는 기술들을 논하였다. 연속영상으로부터 구해진 optic flow는 영상압축기술인 영상간 부호(inter-frame image coding)에 해당되며 컴퓨터비젼 시스템(computer vision system)에서 이동물체 인식에 사용된다.

• Journal of Communications and Networks
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• 제6권2호
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• pp.173-181
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• 2004

This paper shows a technique for regulating the rate emitted by UWB mobile terminals. This technique is designed to adapt the emission rate to the effects of channel capacity variations. We assume that individual flows are shaped at edge routers by means of dual leaky buckets. The proposal is based on the evaluation of certain parameters, which reflect the channel status, sent to the application layer. This information is generated by the scheduler designed to guarantee appropriate channel sharing for the various traffic components. We describe some results which highlight how performance depends on the specific operating conditions, as well as on the traffic descriptors of the flows, their reciprocal difference, and performance requirements.