• 정보처리학회논문지C
• /
• 제12C권6호
• /
• pp.799-808
• /
• 2005

이 논문에서는 유선망과 무선망간의 끊김없는 연결과 QoS 지원을 위해 Mobile-Assisted 및 Server-Initiated 핸드오버 방법을 이용하는 Low Latency 핸드오버 절차를 제안한다. 주 기능은 서버와 단말로 구성되며, 서버는 네트웍의 상황과 사용자의 선호도들을 고려하여 핸드오버를 위한 최선의 타겟 네트웍을 미리 평가하고 결정하여 두며, 단말은 서버에 의해 결정된 무선망과 링크 연결뿐만 아니라 CoA로 사용할 IP 주소를 미리 받아두는 역할을 수행한다. 이 경우, 만약 유선망에서 예고없이 연결이 해제되는 등의 원인에 의해 핸드오버가 요구되면 서버는 MIH(media independent handover) 방법을 이용하여 물리계층의 핸드오버 트리거를 서버로 전송하고 이를 받은 서버는 직접 게이트웨이로 바인딩 업데이트를 수행함으로써 핸드오버 지연시간을 줄일 수 있다는 것을 보여준다.

• 한국통신학회논문지
• /
• 제30권8B호
• /
• pp.507-513
• /
• 2005

인터넷 사용자의 급속한 증가와 더불어 다양한 멀티미디어 서비스가 출현함에 따라 다중서비스를 지원하는 EPON에서 서비스 품질을 지원하기 위해 트래픽은 우선순위에 따라 분류될 수 있다. EPON망에서의 멀티미디어 응용 서비스는 VoIP(Voice over Internet Protocol)등과 같은 음성 데이터 및 실시간 오디오$\cdot$비디오 등과 같이 지연에 민감한 트래픽을 제공하는 서비스와 BE(Best Effort)와 같은 비실시간 트래픽을 제공하는 서비스로 구분되는데 이러한 서비스들을 적절히 지원하는데 있어서 EPON의 상향 트래픽의 대역 할당 방안을 다룬다. 기존의 제안된 방안을 살펴보고 실시간 트래픽의 성능을 향상시킬 수 있는 새로운 방안을 제시한다. 제시한 방안으로 상향 트래픽의 대역 할당을 지원함으로서 얻을 수 있는 트래픽의 손실률과 지연을 시뮬레이션으로 분석한다.

• Journal of Communications and Networks
• /
• 제14권6호
• /
• pp.653-661
• /
• 2012

High-availability seamless redundancy (HSR) is a redundancy protocol for Ethernet networks that provides two frame copies for each frame sent. Each copy will pass through separate physical paths, pursuing zero fault recovery time. This means that even in the case of a node or a link failure, there is no stoppage of network operations whatsoever. HSR is a potential candidate for the communications of a smart grid, but its main drawback is the unnecessary traffic created due to the duplicated copies of each sent frame, which are generated and circulated inside the network. This downside will degrade network performance and might cause network congestion or even stoppage. In this paper, we present two approaches to solve the above-mentioned problem. The first approach is called quick removing (QR), and is suited to ring or connected ring topologies. The idea is to remove the duplicated frame copies from the network when all the nodes have received one copy of the sent frame and begin to receive the second copy. Therefore, the forwarding of those frame copies until they reach the source node, as occurs in standard HSR, is not needed in QR. Our example shows a traffic reduction of 37.5%compared to the standard HSR protocol. The second approach is called the virtual ring (VRing), which divides any closed-loop HSR network into several VRings. Each VRing will circulate the traffic of a corresponding group of nodes within it. Therefore, the traffic in that group will not affect any of the other network links or nodes, which results in an enhancement of traffic performance. For our sample network, the VRing approach shows a network traffic reduction in the range of 67.7 to 48.4%in a healthy network case and 89.7 to 44.8%in a faulty network case, compared to standard HSR.

• Journal of Communications and Networks
• /
• 제9권4호
• /
• pp.511-523
• /
• 2007

In broadband convergence network(BcN), heterogeneous broadband wired & wireless subnetworks and various terminal equipments will be interconnected. In order to provide end-to-end realtime multimedia services on such heterogeneous networking environment, as a result, two major problems should be resolved: i) Multimedia session establishment & negotiation that adjusts the differences in the capability of multimedia data processing at the end terminal nodes, ii) quality of service(QoS)-guaranteed connection establishment or resource reservation with connection admission control(CAC) in each heterogeneous subnetworks along the path. The session layer signaling(e.g., SIP/SDP) should be extended for QoS negotiation, and must be tightly cooperating with network layer signaling or resource reservation with CAC function. In this paper we propose a session and connection management architecture for the QoS-guaranteed realtime multimedia service provisioning on BcN, with Q-SIP/SDP, resource reservation protocol with traffic engineering extension, and CAC functions. The detailed interaction scenario and related algorithms for QoS-guaranteed realtime multimedia session, resource reservation and connection establishment are explained and analyzed. From the experimental implementation of the proposed scheme on a small scale BcN testbed, we verified that the proposed architecture is applicable for the realtime multimedia service provisioning. We analyze the network performance and QoS parameters in detail.

• Journal of Electrical Engineering and Technology
• /
• 제1권4호
• /
• pp.435-447
• /
• 2006

This paper presents an application of the parallel Adaptive Evolutionary Algorithm (AEA) to search an optimal solution of the service restoration in electric power distribution systems, which is a discrete optimization problem. The main objective of service restoration is, when a fault or overload occurs, to restore as much load as possible by transferring the de-energized load in the out of service area via network reconfiguration to the appropriate adjacent feeders at minimum operational cost without violating operating constraints. This problem has many constraints and it is very difficult to find the optimal solution because of its numerous local minima. In this investigation, a parallel AEA was developed for the service restoration of the distribution systems. In parallel AEA, a genetic algorithm (GA) and an evolution strategy (ES) in an adaptive manner are used in order to combine the merits of two different evolutionary algorithms: the global search capability of the GA and the local search capability of the ES. In the reproduction procedure, proportions of the population by GA and ES are adaptively modulated according to the fitness. After AEA operations, the best solutions of AEA processors are transferred to the neighboring processors. For parallel computing, a PC cluster system consisting of 8 PCs was developed. Each PC employs the 2 GHz Pentium IV CPU and is connected with others through switch based fast Ethernet. To show the validity of the proposed method, the developed algorithm has been tested with a practical distribution system in Korea. From the simulation results, the proposed method found the optimal service restoration strategy. The obtained results were the same as that of the explicit exhaustive search method. Also, it is found that the proposed algorithm is efficient and robust for service restoration of distribution systems in terms of solution quality, speedup, efficiency, and computation time.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
• /
• pp.1229-1230
• /
• 2006

This study is for implementation of PC based Motor fault diagnosis system. By using harmonics and current signals of the motor, this system diagnoses the motor condition by accumulated harmonic contribution rate. In this proposed system that was composed of 5 parts. A sensor, connection box, evaluation board, device server, and main computer are those. There were two types of sensor, one was harmonic sensor the other was current sensors. The signal was acquired by sensor, and transferred to evaluation board. Second one is connection box. Because the output type of sensor and input type of evaluation board is different, connection box was necessary. Third one was evaluation board. The signal from the sensor was converted to digital signal in evaluation board. And this signal was transferred to device server. Fourth one was device server. Device server transferred the data from evaluation board to main computer. And the last one was other parts controlled by main computer in main computer, there were communication and diagnosis algorithms. The result was derived by main computer. In the result, there were 12 categories and 5 levels of motor conditions. The proposed system had some advantages comparing with stand alone type commercial motor fault diagnosis system. The first, by using remote access it was easier to get the conditions of motor. The second, there was no need to handle the sensors when users measured the motor signals. By this property, no one was necessary at motor location site. The third, this system was less restricted by times and places than commercial stand alone type diagnosis system. Therefore users can operate this system only using the main computer. Once the sensors are installed at the motor, users doesn't need to move to check up the condition of motors. Moreover, if there is ethernet hub, many motors can be not only diagnosed at once but also decreased its cost.

• KIEE International Transactions on Power Engineering
• /
• 제5A권2호
• /
• pp.116-124
• /
• 2005

This paper presents an application of the parallel Genetic Algorithm-Tabu Search (GA- TS) algorithm, and that is to search for an optimal solution of a reconfiguration in distribution systems. The aim of the reconfiguration of distribution systems is to determine the appropriate switch position to be opened for loss minimization in radial distribution systems, which is a discrete optimization problem. This problem has many constraints and it is very difficult to solve the optimal switch position because of its numerous local minima. This paper develops a parallel GA- TS algorithm for the reconfiguration of distribution systems. In parallel GA-TS, GA operators are executed for each processor. To prevent solution of low fitness from appearing in the next generation, strings below the average fitness are saved in the tabu list. If best fitness of the GA is not changed for several generations, TS operators are executed for the upper 10$\%$ of the population to enhance the local searching capabilities. With migration operation, the best string of each node is transferred to the neighboring node after predetermined iterations are executed. For parallel computing, we developed a PC-cluster system consisting of 8 PCs. Each PC employs the 2 GHz Pentium IV CPU and is connected with others through switch based rapid Ethernet. To demonstrate the usefulness of the proposed method, the developed algorithm was tested and is compared to a distribution system in the reference paper From the simulation results, we can find that the proposed algorithm is efficient and robust for the reconfiguration of distribution system in terms of the solution quality, speedup, efficiency, and computation time.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 춘계학술대회논문집
• /
• pp.555-560
• /
• 2003

Korean High Speed Train(KHST) has been tested on the high speed test line in Osung site of Korea High Speed Rail Construction Authority (KHRC). since it was developed as G7 Project Plan In 2002. This paper introduces the dynamic test devices in KHST and shows the comparison between the results of test and theoretical computing results which derive from the new model for KHST dynamic behavior. Previous computer simulation model for KHST was developed to review wether the vehicle system was satisfied with the dynamic performance requirements during the design procedure. But It should be applied the results of the parts test for suspension elements in order to compare between the results of computation and real test. Using VAMPIRE Program made by AEA Technology in UK. the new model also was modified. This paper shows that the static wheel loads calculated from new model is similar to test results. For test on high speed line, we prepared the test devices for evaluating the dynamic performances. which was consisted of the accelerometers( based on Kisler Co.) and the data aquisition systems (based on National instrument Co.), and test program coded by LabView 6i program. These lest devices and programs are flexible to extension the channels for adding sensors and connect to the ethernet network. The acceleration of car bodies, bogie frames and axle boxes were compared between the results of computation and test at 150km/. This paper shows that the results of test were high in high frequency band range but similar frequency band range. It might be considered that these differences were caused by the test which did not performed at constant speed for comparison analysis. Also. It will be able to understand the differences and make better results through a lot of tests planed in future.

• 한국인터넷방송통신학회논문지
• /
• 제16권2호
• /
• pp.49-54
• /
• 2016

본 논문에서는 아두이노 기반의 효율적인 홈 시큐리티 모니터링 시스템을 제안한다. 제안하는 홈 시큐리티 모니터링 시스템은 비교적 가격이 저렴한 메인 프로세서인 아두이노와 초음파 센서, 인체 감지 센서를 이용하여 침입여부를 판단하도록 홈 시큐리티 시스템을 구성하였고, 초음파 센서와 인체 감지 센서의 데이터는 아두이노에 연결된 이더넷 쉴드를 통해 웹 서버로 전송하도록 설계하였다. 그리고 웹 서버에서는 저장된 초음파 센서와 인체 감지 센서 데이터를 이용하여 침입여부를 확인하고, JQuery를 이용하여 연결되어 있는 웹캠으로 스냅 샷을 촬영하도록 하였으며, 촬영 된 스냅 샷은 웹 서버에 이미지 파일로 저장되며, HTML5와 CSS, Canvas를 사용하여 사용자는 웹 또는 스마트 디바이스 환경에서 모니터링이 가능하도록 설계하였다. 제안된 홈 시큐리티 모니터링 시스템을 실제 구현함으로서 효율성 검증 결과 기존 홈 시큐리티 시스템에 비해 구성이 쉬워 도면을 보고 쉽게 제작이 가능하였으며, 아두이노를 이용하여 구성과 설치비에 대한 가성비가 뛰어났고, 개인이 오류에 대한 직접적인 대처가 가능해 비용에 대한 효율성과 편리성을 입증하였으며, 신뢰도 높은 데이터를 이용하여 안정적인 시스템 운영이 가능하였다.

• 대한전자공학회논문지TC
• /
• 제48권11호
• /
• pp.73-82
• /
• 2011

무선 인터넷 사용자의 증가, IPTV 확산, 개인 멀티미디어 플랫폼의 다양화 등으로 IP 기반의 패킷 서비스에 대한 요구가 증가함에 따라 TDM 기술을 사용하는 회선 기반의 전송방식에서 이더넷 기반의 패킷 전송방식으로 기술이 진화하고 있다. 본 논문에서는 PBB-TE 기술 및 MPLS-TP 기술을 적용한 패킷 전송망에 대해 소개하고, 패킷 전송망에서 사용자의 다양한 요구조건에 만족하는 서비스 품질 관리 방안을 제시한다. 제안된 플로우 기반의 QoS 관리 방안에서는 입력 프레임을 플로우 별로 구분하여 PTL 터널에 매핑하고 각 플로우 및 PTL 터널 별 대역관리를 수행함으로써 대역충돌 상황에서도 설정된 서비스 품질을 완벽히 보장해 줄 수 있다. 제안된 방안의 성능분석을 위해 각 입력 프레임 별 플로우 및 PTL 터널을 정의하고 각 플로우 및 PTL 터널 별 QoS 파라메터를 설정하였으며 OPNET modeler를 사용하여 모의시험을 수행 하였다.