• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.46-58
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• 2003

The recent Internet is changing from its best-effort service and needs the network structure and traffic engineering, which can support various applications requiring differentiated traffic processing and high quality of service. The extension of the Internet from wired to wireless system generating location-dependent and burst errors make more difficult to support a good service with the existing packet scheduling algorithm. In this paper, we propose a wireless diffserv packet scheduling (WDSPS) algorithm that can provide reliable service in the differentiated wireless internet service network. The proposed scheduling algorithm solves the HOL(head of line) blocking problems of class queue occurred in wireless network, supports the differentiated service for each class which is defined in differentiated service networks and makes possible the gradual and efficient service compensation not only among classes but also among flows to prevent the monopoly of one class or one flow. Through simulations, we show that our proposed WDSPS scheduling algorithm can provide the required QoS differentiation between classes and enhance the service throughput in various wireless network conditions.

• Journal of Internet Computing and Services
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• v.23 no.1
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• pp.125-134
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• 2022

The development of information communication and artificial intelligence technology requires the intelligent command and control (C2) system for Korean military, and various studies are attempted to achieve it. In particular, as a volume ofinformation in the C2 workflow increases exponentially, this study pays attention to the collaborative filtering (CF) and recommendation systems (RS) that can provide the essential information for the users of the C2 system has been developed. The RS performing information filtering in the C2 system should provide an explanatory recommendation and consider the context of the tasks and users. In this paper, we propose a contextual pre-filtering CARS framework that recommends information in the C2 workflow. The proposed framework consists of four components: 1) contextual pre-filtering that filters data in advance based on the context and relationship of the users, 2) feature selection to overcome the data sparseness that is a weak point for the CF, 3) the proposed CF with the features distances between the users used to calculate user similarity, and 4) rule-based post filtering to reflect user preferences. In order to evaluate the superiority of this study, various distance methods of the existing CF method were compared to the proposed framework with two experimental datasets in real-world. As a result of comparative experiments, it was shown that the proposed framework was superior in terms of MAE, MSE, and MSLE.

• Proceedings of the Korea Society for Simulation Conference
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• 1998.10a
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• pp.78-81
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• 1998

인터넷에서 통합서비스를 제공하기 위해서는 종단간 다양한 QoS를 지원해야하는데 이를 위해서는 인터넷 뿐 아니라 종단 사용자와 인터넷을 연결하는 랜에서의 QoS 지원이 필요하다. 이에, IETF(Internet Enginnering Task Force)는 특정 링트 계층으로 구성되는 서브넷에서 QoS 보장을 지원하기 위한 기본 골격을 제안하였다. 그런데, 매체 접근 방식에 따라 서브넷이 제공할 수 있는 서비스의 정도가 크게 달라지기 때문에 이러한 IS802모델을 이더넷과 토큰링에 적용한 모델인 이더넷_IS, 토큰링_IS의 구현 방식을 제안하였다. 특별히, 이더넷의 경우 매체 접근 방식의 특성상 IS802모델의 적용만으로는 페이즈 관리자를 제안하고 이더넷_IS 모델에 페이즈 관리자 모듈을 첨가한 페이즈 관리자 모델을 추가로 제안하였다. 시뮬레이션을 통해 기존의 전통적인 이더넷과 토큰링 및 새롭게 표준화된 IS802모델을 적용한 이더넷_IS와 토큰링_IS, 그리고 페이즈 모델간의 성능을 비교하였다. 시뮬레이션 결과에 의하여, 페이즈 모델의 경우 이더넷의 매체 접근 방식을 상당히 보완함으로써 QoS 보장을 요구하는 플로우에 대해서는 망의 여건에 대해 비교적 안정적인 서비스를 제공할 수 있음을 확인 할 수 있었다.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.65-73
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• 2009

IEEE802.11 Wireless LAN(WLAN) is being widely used in public space such as airport, and increases the networking boundary in campus and enterprise, and it has lastly attracted considerable attention for mesh network and converged network with other 3G mobile communication networks. In WLAN, load balancing among Access Points(AP) is an important issue for efficient resource management or supporting the Quality of Service(QoS) of traffic, but most researches focused on the AP selection in network entry or roaming of Stations(STA). In this paper, we propose an AP-Initiated Flow Redirection(FR) for AP load balancing by monitoring AP's availability in the true sense. When the AP's resource becomes almost saturated, that is used more than a specific threshold, the AP queries the roaming possible neighbor APs about their availability and calculates the distribution of traffic load with statistical methods such as entropy or chi-square. Finally, the AP decides flows and new APs for redirection and performs it. Our simulation results show that our FR mechanism increases the performance in the various views.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.118-127
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• 2010

Current TCP/IP-based Internet architecture has been used for over 30 years, however it will confront with fundamental problems due to new protocol extension limitation since communication environments will change drastically and various user requirements will be emerging in near future. To solve these problems, major countries have started Future Internet researches based on clean slate approach and they will deploy large-scale testbed to experiment and verify new functions. OpenFlow switch technology has been proposed as a new experimental technology for independent protocol that can utilized the legacy network devices and does not interfere with the production Internet traffic. Korea also started Future Internet testbed project called FIRST and OpenFlow switch with NetFPGA card will be used to deploy this testbed. To interconnect distributed testbed using OpenFlow switches, logical tunnel should be established by encapsulating MAC frame inside a unicast IP packet between OpenFlow switches because OpenFlow switches are not directly connected. In this paper, we have implemented a NetFPGA-based that performs MAC in IP tunneling between various OpenFlow switch sites implemented in domestic research network KOREN. The performance evaluation shows that the NetFPGA-based capsulator reveals better performance than the software-based tunneling and it can be utilized as a testbed for experimentation of Future Internet technologies.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.81-85
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• 2009

본 논문은 VoIP, IPTV, VoD 등의 실시간 서비스 품질을 네트워크 노드에서 모니터링함으로써네트워크에서 발생한 품질이상을 분석할 수 있는 스위치 칩을 설계하였다. 인터넷 서비스의 특성상 단대단 서비스에 기반한 실시간서비스는 품질이상이 발생한 위치를 정확하게 분석할 수 없기 때문에 유지보수에 어려움이 있다. 이러한 문제를 해결하기 위해 본 논문에서는 실시간서비스에 해당하는 플로우를 등록하고 해당 플로우가 장치내에서 발생한 패킷손실, RTP 시퀀스 넘버를 참조하여 이전 장치에서의 패킷손실, 패킷의 IAT(Inter Arrival Time), 대역폭, 그리고 장치내 지연을 실시간으로 측정할 수 있는 기능을 가진 AVB(Audio/Video Bridge)칩을 구현하기 위해 IEEE802.1AS를 기만한 시간동기 프로토콜의 정확성을 시뮬레이션하고, FPGA를 이용하여 구현한 AVB 스위치칩에서 타임스템프의 정확성을 확인함으로써 실시간서비스의 품질을 네트워크에서 실시간으로 모니터링 할 수 있는 가능성을 확인하였다.

• Journal of KIISE:Software and Applications
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• v.30 no.5_6
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• pp.529-539
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• 2003

Due to the emersion of J2EE (Java 2, Enterprise Edition), many enterprises inside and outside of the country have been developing the enterprise applications appropriate to the J2EE model. With the help of the component model of Enterprise JavaBeans (EJB) which is the J2EE core technology, we can develop the distributed object applications quite simple. EJB application can be implemented by using the component-oriented object transaction middleware and the most applications utilize the distributed transaction. Due to these characteristics, EJB technology became popular and then the study for EJB based application has been done quite actively. However, the research of techniques for the performance monitoring during run-time of the EJB applications has not been done enough. In this paper, we propose the techniques for monitoring the performance of EJB Application on the run time. First, we explore the workflow for the EJB application service and classily the internal operation into several elements. The proposed techniques provide monitoring the performance elements between the classified elements. We can also monitor by extracting the performance information like state transition and process time of the bean which is related to the lifetime occurred during one workflow, and the resource utilization rate.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.15-21
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• 2018

Per-packet scheduling is more suitable than per-flow scheduling to reduce the flow completion time by efficiently utilizing resources in data center networks. Recently, many per-packet scheduling schemes utilizing multiple paths have been proposed. However, to mitigate the negative effect of packet reordering on TCP performance, most of the schemes require supplemental measures such as putting packets in order at the lower layer. In this study, we investigate how well DCTCP, which is a representative TCP for data center networks, performs with per-packet scheduling through simulation. Simulation results show that DCTCP keeps the queue length short but that DCTCP shows low fairness due to the way of reducing the congestion window by ECN.

• 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.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.255-263
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• 2004

광명시 경륜 경기장은 국민 체육진흥공단에서 턴키(Turn key)공사로 발주하였고, CS구조+공간건축+대우건설, 삼성건설, 태영건설의 제출안이 당선되어 현재 시공중에 있다. 경기장의 저층부는 PC로 설계되었고, 지붕은 철골 트러스를 사용한 Dome 형상으로 이루어져 있다. 돔 지붕의 개념은 지붕에 물을 부었을 때 가장 흘러가기 쉬운 방향으로 트러스를 배치하여 유연한 힘의 흐름을 유도하는 것이다. 143.6m(폭)${\times}$183.5m(길이)${\times}$21m(높이)의 지붕엔 지붕의 개념인 Flow Truss를 물이 흐르는 방향의 방사형으로 배치하고, 내부에 압축링(Compression Ring Truss)과 외부에 인장링(Tension Ring Truss)를 설치하여 힘의 흐름을 단순화시켰고, 실내에서 보기에 플로우 트러스의 간격을 넓게 유지함으로써 개방감을 극대화시켰다. 또한 Flow Truss는 동일한 곡률과 길이로 설계하여 표준화시킴으로써 시공성과 경제성을 동시에 만족토록 하였다. 현재 저층부 시공은 거의 완료된 상황이고, 곧 지붕을 설치할 예정이다. 본 고에서는 돔 지붕의 형성 개념과 설계 과정을 살펴보고, 접합상세 등의 해결에 대해 살펴보겠다.