• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권5호
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• pp.859-876
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• 2010

In this paper, we propose a hierarchical application traffic classification system as an alternative means to overcome the limitations of the port number and payload based methodologies, which are traditionally considered traffic classification methods. The proposed system is a new classification model that hierarchically combines a binary classifier SVM and Support Vector Data Descriptions (SVDDs). The proposed system selects an optimal attribute subset from the bi-directional traffic flows generated by our traffic analysis system (KU-MON) that enables real-time collection and analysis of campus traffic. The system is composed of three layers: The first layer is a binary classifier SVM that performs rapid classification between P2P and non-P2P traffic. The second layer classifies P2P traffic into file-sharing, messenger and TV, based on three SVDDs. The third layer performs specialized classification of all individual application traffic types. Since the proposed system enables both coarse- and fine-grained classification, it can guarantee efficient resource management, such as a stable network environment, seamless bandwidth guarantee and appropriate QoS. Moreover, even when a new application emerges, it can be easily adapted for incremental updating and scaling. Only additional training for the new part of the application traffic is needed instead of retraining the entire system. The performance of the proposed system is validated via experiments which confirm that its recall and precision measures are satisfactory.

• 대한산업공학회지
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• 제25권4호
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• pp.500-509
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• 1999

In this paper, we consider an optimal routing problem when point-to-point and point-to-multipoint connection traffics are offered in an ATM network. We propose a mathematical model for cost-minimizing configuration of a logical network for a given ATM-based BISDN. Our model is essentially identical to the previous one proposed by Kim(Kim, 1996) which finds a virtual-path configuration where the relevant gains obtainable from the ATM technology such as the statistical multiplexing gain and the switching/control cost-saving gain are optimally traded-off. Unlike the Kim's model, however, ours explicitly considers the VP's QoS(Quality of Service) for more efficient utilization of bandwidth. The problem is a large-scale, nonlinear, and mixed-integer problem. The proposed algorithm is based on the local linearization of equivalent-capacity functions and the relaxation of link capacity constraints. As a result, the problem can be decomposed into moderate-sized shortest path problems, Steiner arborescence problems, and LPs. This fact renders our algorithm a lot faster than the previous nonlinear programming algorithm while the solution quality is maintained, hence application to large-scale network problems.

• 대한한방내과학회지
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• 제32권4호
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• pp.584-598
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• 2011

Objectives : Functional dyspepsia is a type of disease characterized by bothersome postprandial fullness, early satiation, epigastric pain and burning without structural gastrointestinal disease. The aim of this study was to analyze the characteristics of functional dyspepsia patients and evaluate changes in symptoms, quality of life, and electrogastrography parameters before and after oriental medical interventions. Methods : We recruited forty-six functional dyspepsia patients who visited gastroenterology clinic in the oriental medicine hospital of Kyung Hee University between November 2009 and February 2011. Patients were assessed for their frequency of dyspepsia (based on short form-Leeds Dyspepsia Questionnaire: SF-LDQ), quality of life (based on functional dyspepsia-related quality of life questionnaire: FD-QoL), gastric motility (based on electrogastrography: EGG) on the first visit. Then, the effect of oriental medical interventions was evaluated using EGG on the second visit. Results : The majority of patients had symptoms of nausea and indigestion. The largest decrease in EGG parameters was found in the indigestion group. The frequency of regurgitation and postprandial EGG power % bradygastria showed a significant correlation. Also, significant correlations were found between some items of FD-QoL and some EGG parameters. Compared to the EGG parameters before oriental medical interventions, some parameters after treatment had positive results, implying the improvement of gastric motility disorder. We also found improvement of EGG parameters in both digestant medicinal group and digestant combined with qi-tonifying medicinal group. Conclusions : The results of this study suggest that clinical application of EGG can be an objective diagnostic tool in functional dyspepsia patients visiting oriental medical hospital.

• 한국통신학회논문지
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• 제37권1C호
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• pp.76-88
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• 2012

군 통신망 응용서비스들을 위한 트래픽 클래스 분류는 NCW (Network Centric Warfare)를 위한 망자원의 효과적인 관리를 제공하기 위한 주요 요구 조건들 중의 하나이다. 많은 표준들과 기관들에서 트래픽 클래스 구분을 제시하고 있으나, 상용 서비스에 초점이 맞추어져 있고 군 특성을 반영하지 못하고 있다. 더욱이 다양한 군 통신 응용서비스들이 제시되고 있으나, 트래픽 분류에 대한 불분명한 기준에 의하여 기관들마다 서로 다른 분류가 이루어지기도 하고 있다. 본 논문에서는 Y.1541을 기반으로 하는 다양한 상용 표준들과 DoD (Department of Defense)의 제안을 기반으로 군 통신 응용서비스에 트래픽 클래스를 부여하고 전달요구 조건을 설정하기 위한 방법론을 제안한다. 제안 방법은 기존 상용 표준들에서 분류한 트래픽 클래스 체계와 DoD 와 FCS (Future Combat System)에서 제시한 군 응용트래픽 클래스 체계를 대상으로 하여 타당성을 검증하였다. 본 논문에서 제안하는 방법은 기존의 또는 새로운 군 통신 응용서비스에 대하여 기계적이고 일관된 트래픽 클래스 부여가 가능하여, 한정된 군 통신 네트워크 자원을 효과적으로 운용하도록 하는 데에 기여가능 할 것으로 기대한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권3호
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• pp.341-357
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• 2010

Forward Error Correction (FEC) techniques have been adopted to overcome packet losses and to improve the quality of video delivery. The efficiency of the FEC has been significantly compromised, however, due to the characteristics of the wireless channel such as burst packet loss, channel fluctuation and lack of Quality of Service (QoS) support. We propose herein an Adaptive Cross-layer FEC mechanism (ACFEC) to enhance the quality of video streaming over 802.11 WLANs. Under the conventional approaches, FEC functions are implemented on the application layer, and required feedback information to calculate redundancy rates. Our proposed ACFEC mechanism, however, leverages the functionalities of different network layers. The Automatic Repeat reQuest (ARQ) function on the Media Access Control (MAC) layer can detect packet losses. Through cooperation with the User Datagram Protocol (UDP), the redundancy rates are adaptively controlled based on the packet loss information. The experiment results demonstrate that the ACFEC mechanism is able to adaptively adjust and control the redundancy rates and, thereby, to overcome both of temporary and persistent channel fluctuations. Consequently, the proposed mechanism, under various network conditions, performs better in recovery than the conventional methods, while generating a much less volume of redundant traffic.

• Journal of Information Technology Applications and Management
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• 제12권1호
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• pp.157-172
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• 2005

Recently, location-based service (LBS) is a hot issue in the field of computer applications. So many papers introducing new techniques of implementing a LBS and new application fields of LBS have been published recently. However, to the best of our knowledge, none of them discusses feasibility test in the prior to the implementation. The importance of a feasibility test for a design prior to the implementation cannot be overemphasized. This paper presents a method of feasibility test for a LBS design. Our method performs three steps. At the first step, we build a Petri net model of the LBS system which is depicted in natural language. The second step is to analyse the Petri net to find errors and flaws in the design. We also improve the Petri net model by fixing the errors and flaws in this step. A feasibility test is the third and final step. In this step. we verify if the design satisfies the user's requirement in the senses of quality of service (QoS) and of minimizing the implementation cost. The third step is performed in the manner of mathematical analysis of the Petri net.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권8호
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• pp.3090-3102
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• 2015

The accuracy of an augmented reality (AR) application is highly dependent on the resolution of the object's image and the device's computational processing capability. Naturally, a mobile smart device equipped with a high-resolution camera becomes the best platform for portable AR services. AR applications require significant energy consumption and very fast response time, which are big burdens to the smart device. However, there are very few ways to overcome these burdens. Computation offloading via mobile cloud computing has the potential to provide energy savings and enhance the performance of applications executed on smart devices. Therefore, in this paper, adaptive mobile computation offloading of mobile AR applications is considered in order to determine optimal offloading points that satisfy the required quality of experience (QoE) while consuming minimum energy of the smart device. AR feature extraction based on SURF algorithm is partitioned into sub-stages in order to determine the optimal AR cloud computational offloading point based on conditions of the smart device, wireless and wired networks, and AR service cloud servers. Tradeoffs in energy savings and processing time are explored also taking network congestion and server load conditions into account.

• 융합보안논문지
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• 제13권6호
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• pp.3-9
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• 2013

정보통신 환경의 급변과 더불어 정보 사회의 기반이 되는 네트워크도 다양한 기술의 발전과 더불어 기존의 고정된 형태에서 벗어나 대용량의 다양한 데이터를 유연하게 전송할 수 있는 능동 가변형으로 진화하고 있다. 더불어 다양한 사용자들의 요구사항을 반영하기 위해 차세대 전달망은 DWDM 전송 시스템과 OXC 로 재구성이 쉬운 동적인 망을 형성하고, 이후에 ROADM/PXC를 기반으로 하는 동적으로 망을 관리하고 제어할 수 있는 GMPLS 기술을 도입하여 망을 운용하는 형태로 발전하고 있다. 본 논문에서는 이러한 차세대 네트워크에서 경로계산을 위해 IETF 제안한 Path Computation Element (PCE) 프로토콜을 구현하기 위한 전체 S/W 구성 및 기능 블록들을 제안하였고, 상위 계층에서 PCE 프로토콜을 사용할 때 필요한 API를 제안하였다.

• 전자공학회논문지
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• 제51권3호
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• pp.22-33
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• 2014

무선 메쉬 네트워크의 표준인 IEEE 802.11s의 매체 접근 방식은 IEEE 802.11e에서 사용되던 EDCA를 기본으로 사용하고, 옵션으로 MCCA를 사용한다. EDCA는 각 트래픽을 네 개의 AC 로 구분하여 차별화된 서비스를 제공하는 기술이고, MCCA는 TDMA 기반의 기술로서 무선 메쉬 라우터 간에 무선 채널의 슬롯을 예약하여 플로우의 대역폭을 보장하는 방식이다. 그러나 MCCA는 이웃 노드와의 대역폭 예약을 통하여 각 플로우들의 요구대역폭과 공정성을 보장할 수는 있지만, 플로우가 멀티미디어 응용의 VBR 트래픽인 경우 예약된 대역폭을 모두 사용하지 못 하고 낭비되는 단점이 있다. 이에 본 논문에서는 MCCA를 사용하는 경우 대역폭이 낭비되는 문제점을 제시하고 이를 효율적으로 개선하여 네트워크 활용도를 높이는 알고리즘인 RSRR (Resource Sharing Round Robin) 스케쥴링을 제안한다. 제안된 알고리즘의 성능을 분석하기 위하여 NS-2 시뮬레이션을 통하여 기존의 MCCA에서 낭비되던 자원을 효과적으로 사용하여 네트워크 활용도가 향상됨을 보였다.

• 전자공학회논문지 IE
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• 제45권1호
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• pp.58-64
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• 2008

본 논문은 인간에 의해 주관적으로 측정되던 이동 멀티미디어 영상 품질에 대한 방법을 개선하기 위한 논문이다. 다양한 열화요인을 가지는 동영상의 정량적이며 객관적인 화질평가를 위해서는 기존의 PSNR의 한계를 보완하고 전송망에서 발생하는 오류를 고려하여야 한다. 따라서, 본 논문에서는 인간의 인지특성을 반영할 수 있는 새로운 객관적 화질측정방법을 제안하였다. 제안된 방법은 멀티미디어 서비스 영상의 품질을 다양하고 정확하게 측정할 수 있으며 서비스 가이드라인을 설정하여 고품질 영상서비스를 제공하는 표준안 설정을 위한 측정 방법과 시스템으로 활용될 수 있다.